Thomas Gleixner | 59bd9de | 2019-05-28 10:10:12 -0700 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0-only |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | /* |
| 3 | * linux/fs/namespace.c |
| 4 | * |
| 5 | * (C) Copyright Al Viro 2000, 2001 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 6 | * |
| 7 | * Based on code from fs/super.c, copyright Linus Torvalds and others. |
| 8 | * Heavily rewritten. |
| 9 | */ |
| 10 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | #include <linux/syscalls.h> |
Al Viro | d10577a | 2011-12-07 13:06:11 -0500 | [diff] [blame] | 12 | #include <linux/export.h> |
Randy Dunlap | 16f7e0f | 2006-01-11 12:17:46 -0800 | [diff] [blame] | 13 | #include <linux/capability.h> |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 14 | #include <linux/mnt_namespace.h> |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 15 | #include <linux/user_namespace.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | #include <linux/namei.h> |
| 17 | #include <linux/security.h> |
Ingo Molnar | 5b825c3 | 2017-02-02 17:54:15 +0100 | [diff] [blame] | 18 | #include <linux/cred.h> |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 19 | #include <linux/idr.h> |
Rob Landley | 57f150a | 2013-09-11 14:26:10 -0700 | [diff] [blame] | 20 | #include <linux/init.h> /* init_rootfs */ |
Al Viro | d10577a | 2011-12-07 13:06:11 -0500 | [diff] [blame] | 21 | #include <linux/fs_struct.h> /* get_fs_root et.al. */ |
| 22 | #include <linux/fsnotify.h> /* fsnotify_vfsmount_delete */ |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 23 | #include <linux/file.h> |
Al Viro | d10577a | 2011-12-07 13:06:11 -0500 | [diff] [blame] | 24 | #include <linux/uaccess.h> |
David Howells | 0bb80f2 | 2013-04-12 01:50:06 +0100 | [diff] [blame] | 25 | #include <linux/proc_ns.h> |
Linus Torvalds | 20b4fb4 | 2013-05-01 17:51:54 -0700 | [diff] [blame] | 26 | #include <linux/magic.h> |
Mike Rapoport | 57c8a66 | 2018-10-30 15:09:49 -0700 | [diff] [blame] | 27 | #include <linux/memblock.h> |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 28 | #include <linux/proc_fs.h> |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 29 | #include <linux/task_work.h> |
Ingo Molnar | 9164bb4 | 2017-02-04 01:20:53 +0100 | [diff] [blame] | 30 | #include <linux/sched/task.h> |
David Howells | e262e32d | 2018-11-01 23:07:23 +0000 | [diff] [blame] | 31 | #include <uapi/linux/mount.h> |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 32 | #include <linux/fs_context.h> |
Al Viro | 037f11b | 2019-06-01 18:09:44 -0400 | [diff] [blame] | 33 | #include <linux/shmem_fs.h> |
Christian Brauner | bd30336 | 2021-12-03 12:17:07 +0100 | [diff] [blame] | 34 | #include <linux/mnt_idmapping.h> |
Ingo Molnar | 9164bb4 | 2017-02-04 01:20:53 +0100 | [diff] [blame] | 35 | |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 36 | #include "pnode.h" |
Adrian Bunk | 948730b | 2007-07-15 23:41:25 -0700 | [diff] [blame] | 37 | #include "internal.h" |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 38 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 39 | /* Maximum number of mounts in a mount namespace */ |
Luis Chamberlain | ab171b9 | 2022-01-21 22:13:27 -0800 | [diff] [blame] | 40 | static unsigned int sysctl_mount_max __read_mostly = 100000; |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 41 | |
Alexey Dobriyan | 68279f9 | 2023-10-11 19:55:00 +0300 | [diff] [blame] | 42 | static unsigned int m_hash_mask __ro_after_init; |
| 43 | static unsigned int m_hash_shift __ro_after_init; |
| 44 | static unsigned int mp_hash_mask __ro_after_init; |
| 45 | static unsigned int mp_hash_shift __ro_after_init; |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 46 | |
| 47 | static __initdata unsigned long mhash_entries; |
| 48 | static int __init set_mhash_entries(char *str) |
| 49 | { |
| 50 | if (!str) |
| 51 | return 0; |
| 52 | mhash_entries = simple_strtoul(str, &str, 0); |
| 53 | return 1; |
| 54 | } |
| 55 | __setup("mhash_entries=", set_mhash_entries); |
| 56 | |
| 57 | static __initdata unsigned long mphash_entries; |
| 58 | static int __init set_mphash_entries(char *str) |
| 59 | { |
| 60 | if (!str) |
| 61 | return 0; |
| 62 | mphash_entries = simple_strtoul(str, &str, 0); |
| 63 | return 1; |
| 64 | } |
| 65 | __setup("mphash_entries=", set_mphash_entries); |
Eric Dumazet | 13f14b4 | 2008-02-06 01:37:57 -0800 | [diff] [blame] | 66 | |
Al Viro | c7999c3 | 2014-02-27 14:40:10 -0500 | [diff] [blame] | 67 | static u64 event; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 68 | static DEFINE_IDA(mnt_id_ida); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 69 | static DEFINE_IDA(mnt_group_ida); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 70 | |
Alexey Dobriyan | 68279f9 | 2023-10-11 19:55:00 +0300 | [diff] [blame] | 71 | static struct hlist_head *mount_hashtable __ro_after_init; |
| 72 | static struct hlist_head *mountpoint_hashtable __ro_after_init; |
| 73 | static struct kmem_cache *mnt_cache __ro_after_init; |
Al Viro | 59aa0da | 2013-09-16 21:34:53 -0400 | [diff] [blame] | 74 | static DECLARE_RWSEM(namespace_sem); |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 75 | static HLIST_HEAD(unmounted); /* protected by namespace_sem */ |
| 76 | static LIST_HEAD(ex_mountpoints); /* protected by namespace_sem */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 77 | |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 78 | struct mount_kattr { |
| 79 | unsigned int attr_set; |
| 80 | unsigned int attr_clr; |
| 81 | unsigned int propagation; |
| 82 | unsigned int lookup_flags; |
| 83 | bool recurse; |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 84 | struct user_namespace *mnt_userns; |
Christian Brauner | 256c8ae | 2022-10-26 12:51:27 +0200 | [diff] [blame] | 85 | struct mnt_idmap *mnt_idmap; |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 86 | }; |
| 87 | |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 88 | /* /sys/fs */ |
Alexey Dobriyan | 68279f9 | 2023-10-11 19:55:00 +0300 | [diff] [blame] | 89 | struct kobject *fs_kobj __ro_after_init; |
Greg Kroah-Hartman | 00d2666 | 2007-10-29 14:17:23 -0600 | [diff] [blame] | 90 | EXPORT_SYMBOL_GPL(fs_kobj); |
Miklos Szeredi | f87fd4c | 2006-01-16 22:14:23 -0800 | [diff] [blame] | 91 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 92 | /* |
| 93 | * vfsmount lock may be taken for read to prevent changes to the |
| 94 | * vfsmount hash, ie. during mountpoint lookups or walking back |
| 95 | * up the tree. |
| 96 | * |
| 97 | * It should be taken for write in all cases where the vfsmount |
| 98 | * tree or hash is modified or when a vfsmount structure is modified. |
| 99 | */ |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 100 | __cacheline_aligned_in_smp DEFINE_SEQLOCK(mount_lock); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 101 | |
Christian Brauner | d033cb6 | 2021-01-21 14:19:49 +0100 | [diff] [blame] | 102 | static inline void lock_mount_hash(void) |
| 103 | { |
| 104 | write_seqlock(&mount_lock); |
| 105 | } |
| 106 | |
| 107 | static inline void unlock_mount_hash(void) |
| 108 | { |
| 109 | write_sequnlock(&mount_lock); |
| 110 | } |
| 111 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 112 | static inline struct hlist_head *m_hash(struct vfsmount *mnt, struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 113 | { |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 114 | unsigned long tmp = ((unsigned long)mnt / L1_CACHE_BYTES); |
| 115 | tmp += ((unsigned long)dentry / L1_CACHE_BYTES); |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 116 | tmp = tmp + (tmp >> m_hash_shift); |
| 117 | return &mount_hashtable[tmp & m_hash_mask]; |
| 118 | } |
| 119 | |
| 120 | static inline struct hlist_head *mp_hash(struct dentry *dentry) |
| 121 | { |
| 122 | unsigned long tmp = ((unsigned long)dentry / L1_CACHE_BYTES); |
| 123 | tmp = tmp + (tmp >> mp_hash_shift); |
| 124 | return &mountpoint_hashtable[tmp & mp_hash_mask]; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 125 | } |
| 126 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 127 | static int mnt_alloc_id(struct mount *mnt) |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 128 | { |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 129 | int res = ida_alloc(&mnt_id_ida, GFP_KERNEL); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 130 | |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 131 | if (res < 0) |
| 132 | return res; |
| 133 | mnt->mnt_id = res; |
| 134 | return 0; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 135 | } |
| 136 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 137 | static void mnt_free_id(struct mount *mnt) |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 138 | { |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 139 | ida_free(&mnt_id_ida, mnt->mnt_id); |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 140 | } |
| 141 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 142 | /* |
| 143 | * Allocate a new peer group ID |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 144 | */ |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 145 | static int mnt_alloc_group_id(struct mount *mnt) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 146 | { |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 147 | int res = ida_alloc_min(&mnt_group_ida, 1, GFP_KERNEL); |
Al Viro | f21f622 | 2009-06-24 03:12:00 -0400 | [diff] [blame] | 148 | |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 149 | if (res < 0) |
| 150 | return res; |
| 151 | mnt->mnt_group_id = res; |
| 152 | return 0; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 153 | } |
| 154 | |
| 155 | /* |
| 156 | * Release a peer group ID |
| 157 | */ |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 158 | void mnt_release_group_id(struct mount *mnt) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 159 | { |
Matthew Wilcox | 169b480 | 2018-06-11 12:31:36 -0400 | [diff] [blame] | 160 | ida_free(&mnt_group_ida, mnt->mnt_group_id); |
Al Viro | 15169fe | 2011-11-25 00:50:41 -0500 | [diff] [blame] | 161 | mnt->mnt_group_id = 0; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 162 | } |
| 163 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 164 | /* |
| 165 | * vfsmount lock must be held for read |
| 166 | */ |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 167 | static inline void mnt_add_count(struct mount *mnt, int n) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 168 | { |
| 169 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 170 | this_cpu_add(mnt->mnt_pcp->mnt_count, n); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 171 | #else |
| 172 | preempt_disable(); |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 173 | mnt->mnt_count += n; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 174 | preempt_enable(); |
| 175 | #endif |
| 176 | } |
| 177 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 178 | /* |
| 179 | * vfsmount lock must be held for write |
| 180 | */ |
Eric Biggers | edf7ddb | 2020-10-31 21:40:21 -0700 | [diff] [blame] | 181 | int mnt_get_count(struct mount *mnt) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 182 | { |
| 183 | #ifdef CONFIG_SMP |
Eric Biggers | edf7ddb | 2020-10-31 21:40:21 -0700 | [diff] [blame] | 184 | int count = 0; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 185 | int cpu; |
| 186 | |
| 187 | for_each_possible_cpu(cpu) { |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 188 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_count; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 189 | } |
| 190 | |
| 191 | return count; |
| 192 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 193 | return mnt->mnt_count; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 194 | #endif |
| 195 | } |
| 196 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 197 | static struct mount *alloc_vfsmnt(const char *name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 198 | { |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 199 | struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); |
| 200 | if (mnt) { |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 201 | int err; |
| 202 | |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 203 | err = mnt_alloc_id(mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 204 | if (err) |
| 205 | goto out_free_cache; |
| 206 | |
| 207 | if (name) { |
Vasily Averin | 79f6540 | 2021-09-02 14:55:10 -0700 | [diff] [blame] | 208 | mnt->mnt_devname = kstrdup_const(name, |
| 209 | GFP_KERNEL_ACCOUNT); |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 210 | if (!mnt->mnt_devname) |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 211 | goto out_free_id; |
Miklos Szeredi | 73cd49e | 2008-03-26 22:11:34 +0100 | [diff] [blame] | 212 | } |
| 213 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 214 | #ifdef CONFIG_SMP |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 215 | mnt->mnt_pcp = alloc_percpu(struct mnt_pcp); |
| 216 | if (!mnt->mnt_pcp) |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 217 | goto out_free_devname; |
| 218 | |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 219 | this_cpu_add(mnt->mnt_pcp->mnt_count, 1); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 220 | #else |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 221 | mnt->mnt_count = 1; |
| 222 | mnt->mnt_writers = 0; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 223 | #endif |
| 224 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 225 | INIT_HLIST_NODE(&mnt->mnt_hash); |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 226 | INIT_LIST_HEAD(&mnt->mnt_child); |
| 227 | INIT_LIST_HEAD(&mnt->mnt_mounts); |
| 228 | INIT_LIST_HEAD(&mnt->mnt_list); |
| 229 | INIT_LIST_HEAD(&mnt->mnt_expire); |
| 230 | INIT_LIST_HEAD(&mnt->mnt_share); |
| 231 | INIT_LIST_HEAD(&mnt->mnt_slave_list); |
| 232 | INIT_LIST_HEAD(&mnt->mnt_slave); |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 233 | INIT_HLIST_NODE(&mnt->mnt_mp_list); |
Eric W. Biederman | 99b19d1 | 2016-10-24 16:16:13 -0500 | [diff] [blame] | 234 | INIT_LIST_HEAD(&mnt->mnt_umounting); |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 235 | INIT_HLIST_HEAD(&mnt->mnt_stuck_children); |
Christian Brauner | 256c8ae | 2022-10-26 12:51:27 +0200 | [diff] [blame] | 236 | mnt->mnt.mnt_idmap = &nop_mnt_idmap; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 237 | } |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 238 | return mnt; |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 239 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 240 | #ifdef CONFIG_SMP |
| 241 | out_free_devname: |
Andrzej Hajda | fcc139a | 2015-02-13 14:36:41 -0800 | [diff] [blame] | 242 | kfree_const(mnt->mnt_devname); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 243 | #endif |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 244 | out_free_id: |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 245 | mnt_free_id(mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 246 | out_free_cache: |
Al Viro | c63181e | 2011-11-25 02:35:16 -0500 | [diff] [blame] | 247 | kmem_cache_free(mnt_cache, mnt); |
Li Zefan | 88b3878 | 2008-07-21 18:06:36 +0800 | [diff] [blame] | 248 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 249 | } |
| 250 | |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 251 | /* |
| 252 | * Most r/o checks on a fs are for operations that take |
| 253 | * discrete amounts of time, like a write() or unlink(). |
| 254 | * We must keep track of when those operations start |
| 255 | * (for permission checks) and when they end, so that |
| 256 | * we can determine when writes are able to occur to |
| 257 | * a filesystem. |
| 258 | */ |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 259 | /* |
| 260 | * __mnt_is_readonly: check whether a mount is read-only |
| 261 | * @mnt: the mount to check for its write status |
| 262 | * |
| 263 | * This shouldn't be used directly ouside of the VFS. |
| 264 | * It does not guarantee that the filesystem will stay |
| 265 | * r/w, just that it is right *now*. This can not and |
| 266 | * should not be used in place of IS_RDONLY(inode). |
| 267 | * mnt_want/drop_write() will _keep_ the filesystem |
| 268 | * r/w. |
| 269 | */ |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 270 | bool __mnt_is_readonly(struct vfsmount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 271 | { |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 272 | return (mnt->mnt_flags & MNT_READONLY) || sb_rdonly(mnt->mnt_sb); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 273 | } |
| 274 | EXPORT_SYMBOL_GPL(__mnt_is_readonly); |
| 275 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 276 | static inline void mnt_inc_writers(struct mount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 277 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 278 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 279 | this_cpu_inc(mnt->mnt_pcp->mnt_writers); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 280 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 281 | mnt->mnt_writers++; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 282 | #endif |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 283 | } |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 284 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 285 | static inline void mnt_dec_writers(struct mount *mnt) |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 286 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 287 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 288 | this_cpu_dec(mnt->mnt_pcp->mnt_writers); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 289 | #else |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 290 | mnt->mnt_writers--; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 291 | #endif |
| 292 | } |
| 293 | |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 294 | static unsigned int mnt_get_writers(struct mount *mnt) |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 295 | { |
| 296 | #ifdef CONFIG_SMP |
| 297 | unsigned int count = 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 298 | int cpu; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 299 | |
| 300 | for_each_possible_cpu(cpu) { |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 301 | count += per_cpu_ptr(mnt->mnt_pcp, cpu)->mnt_writers; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 302 | } |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 303 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 304 | return count; |
| 305 | #else |
| 306 | return mnt->mnt_writers; |
| 307 | #endif |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 308 | } |
| 309 | |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 310 | static int mnt_is_readonly(struct vfsmount *mnt) |
| 311 | { |
Jan Kara | d7439fb | 2023-06-20 13:28:32 +0200 | [diff] [blame] | 312 | if (READ_ONCE(mnt->mnt_sb->s_readonly_remount)) |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 313 | return 1; |
Jan Kara | d7439fb | 2023-06-20 13:28:32 +0200 | [diff] [blame] | 314 | /* |
| 315 | * The barrier pairs with the barrier in sb_start_ro_state_change() |
| 316 | * making sure if we don't see s_readonly_remount set yet, we also will |
| 317 | * not see any superblock / mount flag changes done by remount. |
| 318 | * It also pairs with the barrier in sb_end_ro_state_change() |
| 319 | * assuring that if we see s_readonly_remount already cleared, we will |
| 320 | * see the values of superblock / mount flags updated by remount. |
| 321 | */ |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 322 | smp_rmb(); |
| 323 | return __mnt_is_readonly(mnt); |
| 324 | } |
| 325 | |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 326 | /* |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 327 | * Most r/o & frozen checks on a fs are for operations that take discrete |
| 328 | * amounts of time, like a write() or unlink(). We must keep track of when |
| 329 | * those operations start (for permission checks) and when they end, so that we |
| 330 | * can determine when writes are able to occur to a filesystem. |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 331 | */ |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 332 | /** |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 333 | * mnt_get_write_access - get write access to a mount without freeze protection |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 334 | * @m: the mount on which to take a write |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 335 | * |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 336 | * This tells the low-level filesystem that a write is about to be performed to |
| 337 | * it, and makes sure that writes are allowed (mnt it read-write) before |
| 338 | * returning success. This operation does not protect against filesystem being |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 339 | * frozen. When the write operation is finished, mnt_put_write_access() must be |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 340 | * called. This is effectively a refcount. |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 341 | */ |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 342 | int mnt_get_write_access(struct vfsmount *m) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 343 | { |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 344 | struct mount *mnt = real_mount(m); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 345 | int ret = 0; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 346 | |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 347 | preempt_disable(); |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 348 | mnt_inc_writers(mnt); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 349 | /* |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 350 | * The store to mnt_inc_writers must be visible before we pass |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 351 | * MNT_WRITE_HOLD loop below, so that the slowpath can see our |
| 352 | * incremented count after it has set MNT_WRITE_HOLD. |
| 353 | */ |
| 354 | smp_mb(); |
Sebastian Andrzej Siewior | 0f8821d | 2021-11-25 13:07:11 +0100 | [diff] [blame] | 355 | might_lock(&mount_lock.lock); |
| 356 | while (READ_ONCE(mnt->mnt.mnt_flags) & MNT_WRITE_HOLD) { |
| 357 | if (!IS_ENABLED(CONFIG_PREEMPT_RT)) { |
| 358 | cpu_relax(); |
| 359 | } else { |
| 360 | /* |
| 361 | * This prevents priority inversion, if the task |
| 362 | * setting MNT_WRITE_HOLD got preempted on a remote |
| 363 | * CPU, and it prevents life lock if the task setting |
| 364 | * MNT_WRITE_HOLD has a lower priority and is bound to |
| 365 | * the same CPU as the task that is spinning here. |
| 366 | */ |
| 367 | preempt_enable(); |
| 368 | lock_mount_hash(); |
| 369 | unlock_mount_hash(); |
| 370 | preempt_disable(); |
| 371 | } |
| 372 | } |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 373 | /* |
Jan Kara | d7439fb | 2023-06-20 13:28:32 +0200 | [diff] [blame] | 374 | * The barrier pairs with the barrier sb_start_ro_state_change() making |
| 375 | * sure that if we see MNT_WRITE_HOLD cleared, we will also see |
| 376 | * s_readonly_remount set (or even SB_RDONLY / MNT_READONLY flags) in |
| 377 | * mnt_is_readonly() and bail in case we are racing with remount |
| 378 | * read-only. |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 379 | */ |
| 380 | smp_rmb(); |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 381 | if (mnt_is_readonly(m)) { |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 382 | mnt_dec_writers(mnt); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 383 | ret = -EROFS; |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 384 | } |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 385 | preempt_enable(); |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 386 | |
| 387 | return ret; |
| 388 | } |
Amir Goldstein | ddf9e2f | 2023-09-08 16:29:00 +0300 | [diff] [blame] | 389 | EXPORT_SYMBOL_GPL(mnt_get_write_access); |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 390 | |
| 391 | /** |
| 392 | * mnt_want_write - get write access to a mount |
| 393 | * @m: the mount on which to take a write |
| 394 | * |
| 395 | * This tells the low-level filesystem that a write is about to be performed to |
| 396 | * it, and makes sure that writes are allowed (mount is read-write, filesystem |
| 397 | * is not frozen) before returning success. When the write operation is |
| 398 | * finished, mnt_drop_write() must be called. This is effectively a refcount. |
| 399 | */ |
| 400 | int mnt_want_write(struct vfsmount *m) |
| 401 | { |
| 402 | int ret; |
| 403 | |
| 404 | sb_start_write(m->mnt_sb); |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 405 | ret = mnt_get_write_access(m); |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 406 | if (ret) |
| 407 | sb_end_write(m->mnt_sb); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 408 | return ret; |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 409 | } |
| 410 | EXPORT_SYMBOL_GPL(mnt_want_write); |
| 411 | |
| 412 | /** |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 413 | * mnt_get_write_access_file - get write access to a file's mount |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 414 | * @file: the file who's mount on which to take a write |
| 415 | * |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 416 | * This is like mnt_get_write_access, but if @file is already open for write it |
Eric Biggers | 14e43bf4 | 2020-09-22 09:44:18 -0700 | [diff] [blame] | 417 | * skips incrementing mnt_writers (since the open file already has a reference) |
| 418 | * and instead only does the check for emergency r/o remounts. This must be |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 419 | * paired with mnt_put_write_access_file. |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 420 | */ |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 421 | int mnt_get_write_access_file(struct file *file) |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 422 | { |
Eric Biggers | 14e43bf4 | 2020-09-22 09:44:18 -0700 | [diff] [blame] | 423 | if (file->f_mode & FMODE_WRITER) { |
| 424 | /* |
| 425 | * Superblock may have become readonly while there are still |
| 426 | * writable fd's, e.g. due to a fs error with errors=remount-ro |
| 427 | */ |
| 428 | if (__mnt_is_readonly(file->f_path.mnt)) |
| 429 | return -EROFS; |
| 430 | return 0; |
| 431 | } |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 432 | return mnt_get_write_access(file->f_path.mnt); |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 433 | } |
| 434 | |
| 435 | /** |
Miklos Szeredi | 7c6893e | 2017-09-05 12:53:12 +0200 | [diff] [blame] | 436 | * mnt_want_write_file - get write access to a file's mount |
| 437 | * @file: the file who's mount on which to take a write |
| 438 | * |
Eric Biggers | 14e43bf4 | 2020-09-22 09:44:18 -0700 | [diff] [blame] | 439 | * This is like mnt_want_write, but if the file is already open for writing it |
| 440 | * skips incrementing mnt_writers (since the open file already has a reference) |
| 441 | * and instead only does the freeze protection and the check for emergency r/o |
| 442 | * remounts. This must be paired with mnt_drop_write_file. |
Miklos Szeredi | 7c6893e | 2017-09-05 12:53:12 +0200 | [diff] [blame] | 443 | */ |
| 444 | int mnt_want_write_file(struct file *file) |
| 445 | { |
| 446 | int ret; |
| 447 | |
Miklos Szeredi | a6795a5 | 2018-07-18 15:44:43 +0200 | [diff] [blame] | 448 | sb_start_write(file_inode(file)->i_sb); |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 449 | ret = mnt_get_write_access_file(file); |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 450 | if (ret) |
Miklos Szeredi | a6795a5 | 2018-07-18 15:44:43 +0200 | [diff] [blame] | 451 | sb_end_write(file_inode(file)->i_sb); |
Miklos Szeredi | 7c6893e | 2017-09-05 12:53:12 +0200 | [diff] [blame] | 452 | return ret; |
| 453 | } |
npiggin@suse.de | 96029c4 | 2009-04-26 20:25:55 +1000 | [diff] [blame] | 454 | EXPORT_SYMBOL_GPL(mnt_want_write_file); |
| 455 | |
| 456 | /** |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 457 | * mnt_put_write_access - give up write access to a mount |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 458 | * @mnt: the mount on which to give up write access |
| 459 | * |
| 460 | * Tells the low-level filesystem that we are done |
| 461 | * performing writes to it. Must be matched with |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 462 | * mnt_get_write_access() call above. |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 463 | */ |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 464 | void mnt_put_write_access(struct vfsmount *mnt) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 465 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 466 | preempt_disable(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 467 | mnt_dec_writers(real_mount(mnt)); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 468 | preempt_enable(); |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 469 | } |
Amir Goldstein | ddf9e2f | 2023-09-08 16:29:00 +0300 | [diff] [blame] | 470 | EXPORT_SYMBOL_GPL(mnt_put_write_access); |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 471 | |
| 472 | /** |
| 473 | * mnt_drop_write - give up write access to a mount |
| 474 | * @mnt: the mount on which to give up write access |
| 475 | * |
| 476 | * Tells the low-level filesystem that we are done performing writes to it and |
| 477 | * also allows filesystem to be frozen again. Must be matched with |
| 478 | * mnt_want_write() call above. |
| 479 | */ |
| 480 | void mnt_drop_write(struct vfsmount *mnt) |
| 481 | { |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 482 | mnt_put_write_access(mnt); |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 483 | sb_end_write(mnt->mnt_sb); |
| 484 | } |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 485 | EXPORT_SYMBOL_GPL(mnt_drop_write); |
| 486 | |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 487 | void mnt_put_write_access_file(struct file *file) |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 488 | { |
Eric Biggers | 14e43bf4 | 2020-09-22 09:44:18 -0700 | [diff] [blame] | 489 | if (!(file->f_mode & FMODE_WRITER)) |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 490 | mnt_put_write_access(file->f_path.mnt); |
Jan Kara | eb04c28 | 2012-06-12 16:20:35 +0200 | [diff] [blame] | 491 | } |
| 492 | |
Miklos Szeredi | 7c6893e | 2017-09-05 12:53:12 +0200 | [diff] [blame] | 493 | void mnt_drop_write_file(struct file *file) |
| 494 | { |
Amir Goldstein | 3e15dcf | 2023-09-08 16:28:59 +0300 | [diff] [blame] | 495 | mnt_put_write_access_file(file); |
Miklos Szeredi | 7c6893e | 2017-09-05 12:53:12 +0200 | [diff] [blame] | 496 | sb_end_write(file_inode(file)->i_sb); |
| 497 | } |
Al Viro | 2a79f17 | 2011-12-09 08:06:57 -0500 | [diff] [blame] | 498 | EXPORT_SYMBOL(mnt_drop_write_file); |
| 499 | |
Christian Brauner | 538f4f02 | 2022-02-03 14:14:07 +0100 | [diff] [blame] | 500 | /** |
| 501 | * mnt_hold_writers - prevent write access to the given mount |
| 502 | * @mnt: mnt to prevent write access to |
| 503 | * |
| 504 | * Prevents write access to @mnt if there are no active writers for @mnt. |
| 505 | * This function needs to be called and return successfully before changing |
| 506 | * properties of @mnt that need to remain stable for callers with write access |
| 507 | * to @mnt. |
| 508 | * |
| 509 | * After this functions has been called successfully callers must pair it with |
| 510 | * a call to mnt_unhold_writers() in order to stop preventing write access to |
| 511 | * @mnt. |
| 512 | * |
| 513 | * Context: This function expects lock_mount_hash() to be held serializing |
| 514 | * setting MNT_WRITE_HOLD. |
| 515 | * Return: On success 0 is returned. |
| 516 | * On error, -EBUSY is returned. |
| 517 | */ |
Christian Brauner | fbdc2f6 | 2021-01-21 14:19:51 +0100 | [diff] [blame] | 518 | static inline int mnt_hold_writers(struct mount *mnt) |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 519 | { |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 520 | mnt->mnt.mnt_flags |= MNT_WRITE_HOLD; |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 521 | /* |
| 522 | * After storing MNT_WRITE_HOLD, we'll read the counters. This store |
| 523 | * should be visible before we do. |
| 524 | */ |
| 525 | smp_mb(); |
| 526 | |
| 527 | /* |
| 528 | * With writers on hold, if this value is zero, then there are |
| 529 | * definitely no active writers (although held writers may subsequently |
| 530 | * increment the count, they'll have to wait, and decrement it after |
| 531 | * seeing MNT_READONLY). |
| 532 | * |
| 533 | * It is OK to have counter incremented on one CPU and decremented on |
| 534 | * another: the sum will add up correctly. The danger would be when we |
| 535 | * sum up each counter, if we read a counter before it is incremented, |
| 536 | * but then read another CPU's count which it has been subsequently |
| 537 | * decremented from -- we would see more decrements than we should. |
| 538 | * MNT_WRITE_HOLD protects against this scenario, because |
| 539 | * mnt_want_write first increments count, then smp_mb, then spins on |
| 540 | * MNT_WRITE_HOLD, so it can't be decremented by another CPU while |
| 541 | * we're counting up here. |
| 542 | */ |
Nick Piggin | c6653a8 | 2011-01-07 17:50:10 +1100 | [diff] [blame] | 543 | if (mnt_get_writers(mnt) > 0) |
Christian Brauner | fbdc2f6 | 2021-01-21 14:19:51 +0100 | [diff] [blame] | 544 | return -EBUSY; |
| 545 | |
| 546 | return 0; |
| 547 | } |
| 548 | |
Christian Brauner | 538f4f02 | 2022-02-03 14:14:07 +0100 | [diff] [blame] | 549 | /** |
| 550 | * mnt_unhold_writers - stop preventing write access to the given mount |
| 551 | * @mnt: mnt to stop preventing write access to |
| 552 | * |
| 553 | * Stop preventing write access to @mnt allowing callers to gain write access |
| 554 | * to @mnt again. |
| 555 | * |
| 556 | * This function can only be called after a successful call to |
| 557 | * mnt_hold_writers(). |
| 558 | * |
| 559 | * Context: This function expects lock_mount_hash() to be held. |
| 560 | */ |
Christian Brauner | fbdc2f6 | 2021-01-21 14:19:51 +0100 | [diff] [blame] | 561 | static inline void mnt_unhold_writers(struct mount *mnt) |
| 562 | { |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 563 | /* |
| 564 | * MNT_READONLY must become visible before ~MNT_WRITE_HOLD, so writers |
| 565 | * that become unheld will see MNT_READONLY. |
| 566 | */ |
| 567 | smp_wmb(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 568 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
Christian Brauner | fbdc2f6 | 2021-01-21 14:19:51 +0100 | [diff] [blame] | 569 | } |
| 570 | |
| 571 | static int mnt_make_readonly(struct mount *mnt) |
| 572 | { |
| 573 | int ret; |
| 574 | |
| 575 | ret = mnt_hold_writers(mnt); |
| 576 | if (!ret) |
| 577 | mnt->mnt.mnt_flags |= MNT_READONLY; |
| 578 | mnt_unhold_writers(mnt); |
Dave Hansen | 3d73363 | 2008-02-15 14:37:59 -0800 | [diff] [blame] | 579 | return ret; |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 580 | } |
Dave Hansen | 8366025 | 2008-02-15 14:37:30 -0800 | [diff] [blame] | 581 | |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 582 | int sb_prepare_remount_readonly(struct super_block *sb) |
| 583 | { |
| 584 | struct mount *mnt; |
| 585 | int err = 0; |
| 586 | |
Miklos Szeredi | 8e8b879 | 2011-11-21 12:11:33 +0100 | [diff] [blame] | 587 | /* Racy optimization. Recheck the counter under MNT_WRITE_HOLD */ |
| 588 | if (atomic_long_read(&sb->s_remove_count)) |
| 589 | return -EBUSY; |
| 590 | |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 591 | lock_mount_hash(); |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 592 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
| 593 | if (!(mnt->mnt.mnt_flags & MNT_READONLY)) { |
Christian Brauner | ad1844a | 2022-02-03 14:14:10 +0100 | [diff] [blame] | 594 | err = mnt_hold_writers(mnt); |
| 595 | if (err) |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 596 | break; |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 597 | } |
| 598 | } |
Miklos Szeredi | 8e8b879 | 2011-11-21 12:11:33 +0100 | [diff] [blame] | 599 | if (!err && atomic_long_read(&sb->s_remove_count)) |
| 600 | err = -EBUSY; |
| 601 | |
Jan Kara | d7439fb | 2023-06-20 13:28:32 +0200 | [diff] [blame] | 602 | if (!err) |
| 603 | sb_start_ro_state_change(sb); |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 604 | list_for_each_entry(mnt, &sb->s_mounts, mnt_instance) { |
| 605 | if (mnt->mnt.mnt_flags & MNT_WRITE_HOLD) |
| 606 | mnt->mnt.mnt_flags &= ~MNT_WRITE_HOLD; |
| 607 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 608 | unlock_mount_hash(); |
Miklos Szeredi | 4ed5e82f | 2011-11-21 12:11:31 +0100 | [diff] [blame] | 609 | |
| 610 | return err; |
| 611 | } |
| 612 | |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 613 | static void free_vfsmnt(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 614 | { |
Christian Brauner | 256c8ae | 2022-10-26 12:51:27 +0200 | [diff] [blame] | 615 | mnt_idmap_put(mnt_idmap(&mnt->mnt)); |
Andrzej Hajda | fcc139a | 2015-02-13 14:36:41 -0800 | [diff] [blame] | 616 | kfree_const(mnt->mnt_devname); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 617 | #ifdef CONFIG_SMP |
Al Viro | 68e8a9f | 2011-11-24 22:53:09 -0500 | [diff] [blame] | 618 | free_percpu(mnt->mnt_pcp); |
npiggin@suse.de | d3ef3d7 | 2009-04-26 20:25:54 +1000 | [diff] [blame] | 619 | #endif |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 620 | kmem_cache_free(mnt_cache, mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 621 | } |
| 622 | |
David Howells | 8ffcb32 | 2014-01-24 12:17:54 +0000 | [diff] [blame] | 623 | static void delayed_free_vfsmnt(struct rcu_head *head) |
| 624 | { |
| 625 | free_vfsmnt(container_of(head, struct mount, mnt_rcu)); |
| 626 | } |
| 627 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 628 | /* call under rcu_read_lock */ |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 629 | int __legitimize_mnt(struct vfsmount *bastard, unsigned seq) |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 630 | { |
| 631 | struct mount *mnt; |
| 632 | if (read_seqretry(&mount_lock, seq)) |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 633 | return 1; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 634 | if (bastard == NULL) |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 635 | return 0; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 636 | mnt = real_mount(bastard); |
| 637 | mnt_add_count(mnt, 1); |
Al Viro | 119e1ef | 2018-08-09 17:51:32 -0400 | [diff] [blame] | 638 | smp_mb(); // see mntput_no_expire() |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 639 | if (likely(!read_seqretry(&mount_lock, seq))) |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 640 | return 0; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 641 | if (bastard->mnt_flags & MNT_SYNC_UMOUNT) { |
| 642 | mnt_add_count(mnt, -1); |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 643 | return 1; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 644 | } |
Al Viro | 119e1ef | 2018-08-09 17:51:32 -0400 | [diff] [blame] | 645 | lock_mount_hash(); |
| 646 | if (unlikely(bastard->mnt_flags & MNT_DOOMED)) { |
| 647 | mnt_add_count(mnt, -1); |
| 648 | unlock_mount_hash(); |
| 649 | return 1; |
| 650 | } |
| 651 | unlock_mount_hash(); |
| 652 | /* caller will mntput() */ |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 653 | return -1; |
| 654 | } |
| 655 | |
| 656 | /* call under rcu_read_lock */ |
Al Viro | 7e4745a | 2022-07-05 12:22:46 -0400 | [diff] [blame] | 657 | static bool legitimize_mnt(struct vfsmount *bastard, unsigned seq) |
Al Viro | 294d71f | 2015-05-08 11:43:53 -0400 | [diff] [blame] | 658 | { |
| 659 | int res = __legitimize_mnt(bastard, seq); |
| 660 | if (likely(!res)) |
| 661 | return true; |
| 662 | if (unlikely(res < 0)) { |
| 663 | rcu_read_unlock(); |
| 664 | mntput(bastard); |
| 665 | rcu_read_lock(); |
| 666 | } |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 667 | return false; |
| 668 | } |
| 669 | |
Christian Brauner | 104026c | 2023-05-03 13:18:40 +0200 | [diff] [blame] | 670 | /** |
| 671 | * __lookup_mnt - find first child mount |
| 672 | * @mnt: parent mount |
| 673 | * @dentry: mountpoint |
| 674 | * |
| 675 | * If @mnt has a child mount @c mounted @dentry find and return it. |
| 676 | * |
| 677 | * Note that the child mount @c need not be unique. There are cases |
| 678 | * where shadow mounts are created. For example, during mount |
| 679 | * propagation when a source mount @mnt whose root got overmounted by a |
| 680 | * mount @o after path lookup but before @namespace_sem could be |
| 681 | * acquired gets copied and propagated. So @mnt gets copied including |
| 682 | * @o. When @mnt is propagated to a destination mount @d that already |
| 683 | * has another mount @n mounted at the same mountpoint then the source |
| 684 | * mount @mnt will be tucked beneath @n, i.e., @n will be mounted on |
| 685 | * @mnt and @mnt mounted on @d. Now both @n and @o are mounted at @mnt |
| 686 | * on @dentry. |
| 687 | * |
| 688 | * Return: The first child of @mnt mounted @dentry or NULL. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 689 | */ |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 690 | struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 691 | { |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 692 | struct hlist_head *head = m_hash(mnt, dentry); |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 693 | struct mount *p; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 694 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 695 | hlist_for_each_entry_rcu(p, head, mnt_hash) |
Al Viro | 474279d | 2013-10-01 16:11:26 -0400 | [diff] [blame] | 696 | if (&p->mnt_parent->mnt == mnt && p->mnt_mountpoint == dentry) |
| 697 | return p; |
| 698 | return NULL; |
| 699 | } |
| 700 | |
| 701 | /* |
David Howells | f015f126 | 2012-06-25 12:55:28 +0100 | [diff] [blame] | 702 | * lookup_mnt - Return the first child mount mounted at path |
| 703 | * |
| 704 | * "First" means first mounted chronologically. If you create the |
| 705 | * following mounts: |
| 706 | * |
| 707 | * mount /dev/sda1 /mnt |
| 708 | * mount /dev/sda2 /mnt |
| 709 | * mount /dev/sda3 /mnt |
| 710 | * |
| 711 | * Then lookup_mnt() on the base /mnt dentry in the root mount will |
| 712 | * return successively the root dentry and vfsmount of /dev/sda1, then |
| 713 | * /dev/sda2, then /dev/sda3, then NULL. |
| 714 | * |
| 715 | * lookup_mnt takes a reference to the found vfsmount. |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 716 | */ |
Al Viro | ca71cf7 | 2016-11-20 19:45:28 -0500 | [diff] [blame] | 717 | struct vfsmount *lookup_mnt(const struct path *path) |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 718 | { |
Al Viro | c710536 | 2011-11-24 18:22:03 -0500 | [diff] [blame] | 719 | struct mount *child_mnt; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 720 | struct vfsmount *m; |
| 721 | unsigned seq; |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 722 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 723 | rcu_read_lock(); |
| 724 | do { |
| 725 | seq = read_seqbegin(&mount_lock); |
| 726 | child_mnt = __lookup_mnt(path->mnt, path->dentry); |
| 727 | m = child_mnt ? &child_mnt->mnt : NULL; |
| 728 | } while (!legitimize_mnt(m, seq)); |
| 729 | rcu_read_unlock(); |
| 730 | return m; |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 731 | } |
| 732 | |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 733 | static inline void lock_ns_list(struct mnt_namespace *ns) |
| 734 | { |
| 735 | spin_lock(&ns->ns_lock); |
| 736 | } |
| 737 | |
| 738 | static inline void unlock_ns_list(struct mnt_namespace *ns) |
| 739 | { |
| 740 | spin_unlock(&ns->ns_lock); |
| 741 | } |
| 742 | |
| 743 | static inline bool mnt_is_cursor(struct mount *mnt) |
| 744 | { |
| 745 | return mnt->mnt.mnt_flags & MNT_CURSOR; |
| 746 | } |
| 747 | |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 748 | /* |
| 749 | * __is_local_mountpoint - Test to see if dentry is a mountpoint in the |
| 750 | * current mount namespace. |
| 751 | * |
| 752 | * The common case is dentries are not mountpoints at all and that |
| 753 | * test is handled inline. For the slow case when we are actually |
| 754 | * dealing with a mountpoint of some kind, walk through all of the |
| 755 | * mounts in the current mount namespace and test to see if the dentry |
| 756 | * is a mountpoint. |
| 757 | * |
| 758 | * The mount_hashtable is not usable in the context because we |
| 759 | * need to identify all mounts that may be in the current mount |
| 760 | * namespace not just a mount that happens to have some specified |
| 761 | * parent mount. |
| 762 | */ |
| 763 | bool __is_local_mountpoint(struct dentry *dentry) |
| 764 | { |
| 765 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; |
| 766 | struct mount *mnt; |
| 767 | bool is_covered = false; |
| 768 | |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 769 | down_read(&namespace_sem); |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 770 | lock_ns_list(ns); |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 771 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 772 | if (mnt_is_cursor(mnt)) |
| 773 | continue; |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 774 | is_covered = (mnt->mnt_mountpoint == dentry); |
| 775 | if (is_covered) |
| 776 | break; |
| 777 | } |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 778 | unlock_ns_list(ns); |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 779 | up_read(&namespace_sem); |
Nikolay Borisov | 5ad05cc | 2020-03-04 18:12:45 +0200 | [diff] [blame] | 780 | |
Eric W. Biederman | 7af1364 | 2013-10-04 19:15:13 -0700 | [diff] [blame] | 781 | return is_covered; |
| 782 | } |
| 783 | |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 784 | static struct mountpoint *lookup_mountpoint(struct dentry *dentry) |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 785 | { |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 786 | struct hlist_head *chain = mp_hash(dentry); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 787 | struct mountpoint *mp; |
| 788 | |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 789 | hlist_for_each_entry(mp, chain, m_hash) { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 790 | if (mp->m_dentry == dentry) { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 791 | mp->m_count++; |
| 792 | return mp; |
| 793 | } |
| 794 | } |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 795 | return NULL; |
| 796 | } |
| 797 | |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 798 | static struct mountpoint *get_mountpoint(struct dentry *dentry) |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 799 | { |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 800 | struct mountpoint *mp, *new = NULL; |
Eric W. Biederman | e2dfa93 | 2014-02-24 17:32:34 -0800 | [diff] [blame] | 801 | int ret; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 802 | |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 803 | if (d_mountpoint(dentry)) { |
Benjamin Coddington | 1e9c75f | 2018-10-03 10:18:33 -0400 | [diff] [blame] | 804 | /* might be worth a WARN_ON() */ |
| 805 | if (d_unlinked(dentry)) |
| 806 | return ERR_PTR(-ENOENT); |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 807 | mountpoint: |
| 808 | read_seqlock_excl(&mount_lock); |
| 809 | mp = lookup_mountpoint(dentry); |
| 810 | read_sequnlock_excl(&mount_lock); |
| 811 | if (mp) |
| 812 | goto done; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 813 | } |
Miklos Szeredi | eed8100 | 2013-09-05 14:39:11 +0200 | [diff] [blame] | 814 | |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 815 | if (!new) |
| 816 | new = kmalloc(sizeof(struct mountpoint), GFP_KERNEL); |
| 817 | if (!new) |
| 818 | return ERR_PTR(-ENOMEM); |
| 819 | |
| 820 | |
| 821 | /* Exactly one processes may set d_mounted */ |
| 822 | ret = d_set_mounted(dentry); |
| 823 | |
| 824 | /* Someone else set d_mounted? */ |
| 825 | if (ret == -EBUSY) |
| 826 | goto mountpoint; |
| 827 | |
| 828 | /* The dentry is not available as a mountpoint? */ |
| 829 | mp = ERR_PTR(ret); |
| 830 | if (ret) |
| 831 | goto done; |
| 832 | |
| 833 | /* Add the new mountpoint to the hash table */ |
| 834 | read_seqlock_excl(&mount_lock); |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 835 | new->m_dentry = dget(dentry); |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 836 | new->m_count = 1; |
| 837 | hlist_add_head(&new->m_hash, mp_hash(dentry)); |
| 838 | INIT_HLIST_HEAD(&new->m_list); |
| 839 | read_sequnlock_excl(&mount_lock); |
| 840 | |
| 841 | mp = new; |
| 842 | new = NULL; |
| 843 | done: |
| 844 | kfree(new); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 845 | return mp; |
| 846 | } |
| 847 | |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 848 | /* |
| 849 | * vfsmount lock must be held. Additionally, the caller is responsible |
| 850 | * for serializing calls for given disposal list. |
| 851 | */ |
| 852 | static void __put_mountpoint(struct mountpoint *mp, struct list_head *list) |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 853 | { |
| 854 | if (!--mp->m_count) { |
| 855 | struct dentry *dentry = mp->m_dentry; |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 856 | BUG_ON(!hlist_empty(&mp->m_list)); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 857 | spin_lock(&dentry->d_lock); |
| 858 | dentry->d_flags &= ~DCACHE_MOUNTED; |
| 859 | spin_unlock(&dentry->d_lock); |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 860 | dput_to_list(dentry, list); |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 861 | hlist_del(&mp->m_hash); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 862 | kfree(mp); |
| 863 | } |
| 864 | } |
| 865 | |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 866 | /* called with namespace_lock and vfsmount lock */ |
| 867 | static void put_mountpoint(struct mountpoint *mp) |
| 868 | { |
| 869 | __put_mountpoint(mp, &ex_mountpoints); |
| 870 | } |
| 871 | |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 872 | static inline int check_mnt(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 873 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 874 | return mnt->mnt_ns == current->nsproxy->mnt_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 875 | } |
| 876 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 877 | /* |
| 878 | * vfsmount lock must be held for write |
| 879 | */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 880 | static void touch_mnt_namespace(struct mnt_namespace *ns) |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 881 | { |
| 882 | if (ns) { |
| 883 | ns->event = ++event; |
| 884 | wake_up_interruptible(&ns->poll); |
| 885 | } |
| 886 | } |
| 887 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 888 | /* |
| 889 | * vfsmount lock must be held for write |
| 890 | */ |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 891 | static void __touch_mnt_namespace(struct mnt_namespace *ns) |
Al Viro | 5addc5d | 2005-11-07 17:15:49 -0500 | [diff] [blame] | 892 | { |
| 893 | if (ns && ns->event != event) { |
| 894 | ns->event = event; |
| 895 | wake_up_interruptible(&ns->poll); |
| 896 | } |
| 897 | } |
| 898 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 899 | /* |
| 900 | * vfsmount lock must be held for write |
| 901 | */ |
Al Viro | e4e5990 | 2019-06-29 12:58:42 -0400 | [diff] [blame] | 902 | static struct mountpoint *unhash_mnt(struct mount *mnt) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 903 | { |
Al Viro | e4e5990 | 2019-06-29 12:58:42 -0400 | [diff] [blame] | 904 | struct mountpoint *mp; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 905 | mnt->mnt_parent = mnt; |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 906 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 907 | list_del_init(&mnt->mnt_child); |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 908 | hlist_del_init_rcu(&mnt->mnt_hash); |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 909 | hlist_del_init(&mnt->mnt_mp_list); |
Al Viro | e4e5990 | 2019-06-29 12:58:42 -0400 | [diff] [blame] | 910 | mp = mnt->mnt_mp; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 911 | mnt->mnt_mp = NULL; |
Al Viro | e4e5990 | 2019-06-29 12:58:42 -0400 | [diff] [blame] | 912 | return mp; |
Eric W. Biederman | 7bdb11de | 2014-12-29 13:03:41 -0600 | [diff] [blame] | 913 | } |
| 914 | |
| 915 | /* |
| 916 | * vfsmount lock must be held for write |
| 917 | */ |
Eric W. Biederman | 6a46c57 | 2015-01-15 22:58:33 -0600 | [diff] [blame] | 918 | static void umount_mnt(struct mount *mnt) |
| 919 | { |
Al Viro | e4e5990 | 2019-06-29 12:58:42 -0400 | [diff] [blame] | 920 | put_mountpoint(unhash_mnt(mnt)); |
Eric W. Biederman | 6a46c57 | 2015-01-15 22:58:33 -0600 | [diff] [blame] | 921 | } |
| 922 | |
| 923 | /* |
| 924 | * vfsmount lock must be held for write |
| 925 | */ |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 926 | void mnt_set_mountpoint(struct mount *mnt, |
| 927 | struct mountpoint *mp, |
Al Viro | 44d964d6 | 2011-11-24 21:28:22 -0500 | [diff] [blame] | 928 | struct mount *child_mnt) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 929 | { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 930 | mp->m_count++; |
Al Viro | 3a2393d | 2011-11-25 03:19:09 -0500 | [diff] [blame] | 931 | mnt_add_count(mnt, 1); /* essentially, that's mntget */ |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 932 | child_mnt->mnt_mountpoint = mp->m_dentry; |
Al Viro | 3a2393d | 2011-11-25 03:19:09 -0500 | [diff] [blame] | 933 | child_mnt->mnt_parent = mnt; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 934 | child_mnt->mnt_mp = mp; |
Eric W. Biederman | 0a5eb7c | 2013-09-22 19:37:01 -0700 | [diff] [blame] | 935 | hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 936 | } |
| 937 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 938 | /** |
| 939 | * mnt_set_mountpoint_beneath - mount a mount beneath another one |
| 940 | * |
| 941 | * @new_parent: the source mount |
| 942 | * @top_mnt: the mount beneath which @new_parent is mounted |
| 943 | * @new_mp: the new mountpoint of @top_mnt on @new_parent |
| 944 | * |
| 945 | * Remove @top_mnt from its current mountpoint @top_mnt->mnt_mp and |
| 946 | * parent @top_mnt->mnt_parent and mount it on top of @new_parent at |
| 947 | * @new_mp. And mount @new_parent on the old parent and old |
| 948 | * mountpoint of @top_mnt. |
| 949 | * |
| 950 | * Context: This function expects namespace_lock() and lock_mount_hash() |
| 951 | * to have been acquired in that order. |
| 952 | */ |
| 953 | static void mnt_set_mountpoint_beneath(struct mount *new_parent, |
| 954 | struct mount *top_mnt, |
| 955 | struct mountpoint *new_mp) |
| 956 | { |
| 957 | struct mount *old_top_parent = top_mnt->mnt_parent; |
| 958 | struct mountpoint *old_top_mp = top_mnt->mnt_mp; |
| 959 | |
| 960 | mnt_set_mountpoint(old_top_parent, old_top_mp, new_parent); |
| 961 | mnt_change_mountpoint(new_parent, new_mp, top_mnt); |
| 962 | } |
| 963 | |
| 964 | |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 965 | static void __attach_mnt(struct mount *mnt, struct mount *parent) |
| 966 | { |
| 967 | hlist_add_head_rcu(&mnt->mnt_hash, |
| 968 | m_hash(&parent->mnt, mnt->mnt_mountpoint)); |
| 969 | list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); |
| 970 | } |
| 971 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 972 | /** |
| 973 | * attach_mnt - mount a mount, attach to @mount_hashtable and parent's |
| 974 | * list of child mounts |
| 975 | * @parent: the parent |
| 976 | * @mnt: the new mount |
| 977 | * @mp: the new mountpoint |
| 978 | * @beneath: whether to mount @mnt beneath or on top of @parent |
| 979 | * |
| 980 | * If @beneath is false, mount @mnt at @mp on @parent. Then attach @mnt |
| 981 | * to @parent's child mount list and to @mount_hashtable. |
| 982 | * |
| 983 | * If @beneath is true, remove @mnt from its current parent and |
| 984 | * mountpoint and mount it on @mp on @parent, and mount @parent on the |
| 985 | * old parent and old mountpoint of @mnt. Finally, attach @parent to |
| 986 | * @mnt_hashtable and @parent->mnt_parent->mnt_mounts. |
| 987 | * |
| 988 | * Note, when __attach_mnt() is called @mnt->mnt_parent already points |
| 989 | * to the correct parent. |
| 990 | * |
| 991 | * Context: This function expects namespace_lock() and lock_mount_hash() |
| 992 | * to have been acquired in that order. |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 993 | */ |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 994 | static void attach_mnt(struct mount *mnt, struct mount *parent, |
| 995 | struct mountpoint *mp, bool beneath) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 996 | { |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 997 | if (beneath) |
| 998 | mnt_set_mountpoint_beneath(mnt, parent, mp); |
| 999 | else |
| 1000 | mnt_set_mountpoint(parent, mp, mnt); |
| 1001 | /* |
| 1002 | * Note, @mnt->mnt_parent has to be used. If @mnt was mounted |
| 1003 | * beneath @parent then @mnt will need to be attached to |
| 1004 | * @parent's old parent, not @parent. IOW, @mnt->mnt_parent |
| 1005 | * isn't the same mount as @parent. |
| 1006 | */ |
| 1007 | __attach_mnt(mnt, mnt->mnt_parent); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1008 | } |
| 1009 | |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 1010 | void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt) |
Al Viro | 12a5b52 | 2014-08-10 03:44:55 -0400 | [diff] [blame] | 1011 | { |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 1012 | struct mountpoint *old_mp = mnt->mnt_mp; |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 1013 | struct mount *old_parent = mnt->mnt_parent; |
| 1014 | |
| 1015 | list_del_init(&mnt->mnt_child); |
| 1016 | hlist_del_init(&mnt->mnt_mp_list); |
| 1017 | hlist_del_init_rcu(&mnt->mnt_hash); |
| 1018 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 1019 | attach_mnt(mnt, parent, mp, false); |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 1020 | |
| 1021 | put_mountpoint(old_mp); |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 1022 | mnt_add_count(old_parent, -1); |
Al Viro | 12a5b52 | 2014-08-10 03:44:55 -0400 | [diff] [blame] | 1023 | } |
| 1024 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1025 | /* |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1026 | * vfsmount lock must be held for write |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1027 | */ |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 1028 | static void commit_tree(struct mount *mnt) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1029 | { |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 1030 | struct mount *parent = mnt->mnt_parent; |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1031 | struct mount *m; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1032 | LIST_HEAD(head); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1033 | struct mnt_namespace *n = parent->mnt_ns; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1034 | |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 1035 | BUG_ON(parent == mnt); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1036 | |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1037 | list_add_tail(&head, &mnt->mnt_list); |
Al Viro | f7a99c5 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 1038 | list_for_each_entry(m, &head, mnt_list) |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1039 | m->mnt_ns = n; |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 1040 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 1041 | list_splice(&head, n->list.prev); |
| 1042 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 1043 | n->mounts += n->pending_mounts; |
| 1044 | n->pending_mounts = 0; |
| 1045 | |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 1046 | __attach_mnt(mnt, parent); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 1047 | touch_mnt_namespace(n); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1048 | } |
| 1049 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1050 | static struct mount *next_mnt(struct mount *p, struct mount *root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1051 | { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 1052 | struct list_head *next = p->mnt_mounts.next; |
| 1053 | if (next == &p->mnt_mounts) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1054 | while (1) { |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1055 | if (p == root) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1056 | return NULL; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 1057 | next = p->mnt_child.next; |
| 1058 | if (next != &p->mnt_parent->mnt_mounts) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1059 | break; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 1060 | p = p->mnt_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1061 | } |
| 1062 | } |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 1063 | return list_entry(next, struct mount, mnt_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1064 | } |
| 1065 | |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1066 | static struct mount *skip_mnt_tree(struct mount *p) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1067 | { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 1068 | struct list_head *prev = p->mnt_mounts.prev; |
| 1069 | while (prev != &p->mnt_mounts) { |
| 1070 | p = list_entry(prev, struct mount, mnt_child); |
| 1071 | prev = p->mnt_mounts.prev; |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1072 | } |
| 1073 | return p; |
| 1074 | } |
| 1075 | |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1076 | /** |
| 1077 | * vfs_create_mount - Create a mount for a configured superblock |
| 1078 | * @fc: The configuration context with the superblock attached |
| 1079 | * |
| 1080 | * Create a mount to an already configured superblock. If necessary, the |
| 1081 | * caller should invoke vfs_get_tree() before calling this. |
| 1082 | * |
| 1083 | * Note that this does not attach the mount to anything. |
| 1084 | */ |
| 1085 | struct vfsmount *vfs_create_mount(struct fs_context *fc) |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1086 | { |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 1087 | struct mount *mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1088 | |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1089 | if (!fc->root) |
| 1090 | return ERR_PTR(-EINVAL); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1091 | |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1092 | mnt = alloc_vfsmnt(fc->source ?: "none"); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1093 | if (!mnt) |
| 1094 | return ERR_PTR(-ENOMEM); |
| 1095 | |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1096 | if (fc->sb_flags & SB_KERNMOUNT) |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 1097 | mnt->mnt.mnt_flags = MNT_INTERNAL; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1098 | |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1099 | atomic_inc(&fc->root->d_sb->s_active); |
| 1100 | mnt->mnt.mnt_sb = fc->root->d_sb; |
| 1101 | mnt->mnt.mnt_root = dget(fc->root); |
| 1102 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
| 1103 | mnt->mnt_parent = mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1104 | |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1105 | lock_mount_hash(); |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1106 | list_add_tail(&mnt->mnt_instance, &mnt->mnt.mnt_sb->s_mounts); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1107 | unlock_mount_hash(); |
Al Viro | b105e27 | 2011-11-24 20:38:33 -0500 | [diff] [blame] | 1108 | return &mnt->mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1109 | } |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1110 | EXPORT_SYMBOL(vfs_create_mount); |
| 1111 | |
| 1112 | struct vfsmount *fc_mount(struct fs_context *fc) |
| 1113 | { |
| 1114 | int err = vfs_get_tree(fc); |
| 1115 | if (!err) { |
| 1116 | up_write(&fc->root->d_sb->s_umount); |
| 1117 | return vfs_create_mount(fc); |
| 1118 | } |
| 1119 | return ERR_PTR(err); |
| 1120 | } |
| 1121 | EXPORT_SYMBOL(fc_mount); |
| 1122 | |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 1123 | struct vfsmount *vfs_kern_mount(struct file_system_type *type, |
| 1124 | int flags, const char *name, |
| 1125 | void *data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1126 | { |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 1127 | struct fs_context *fc; |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1128 | struct vfsmount *mnt; |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 1129 | int ret = 0; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1130 | |
| 1131 | if (!type) |
David Howells | 3e1aeb0 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 1132 | return ERR_PTR(-EINVAL); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1133 | |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 1134 | fc = fs_context_for_mount(type, flags); |
| 1135 | if (IS_ERR(fc)) |
| 1136 | return ERR_CAST(fc); |
| 1137 | |
David Howells | 3e1aeb0 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 1138 | if (name) |
| 1139 | ret = vfs_parse_fs_string(fc, "source", |
| 1140 | name, strlen(name)); |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 1141 | if (!ret) |
| 1142 | ret = parse_monolithic_mount_data(fc, data); |
| 1143 | if (!ret) |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1144 | mnt = fc_mount(fc); |
| 1145 | else |
| 1146 | mnt = ERR_PTR(ret); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1147 | |
David Howells | 9bc61ab | 2018-11-04 03:19:03 -0500 | [diff] [blame] | 1148 | put_fs_context(fc); |
Al Viro | 8f291889 | 2018-11-04 06:48:34 -0500 | [diff] [blame] | 1149 | return mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 1150 | } |
| 1151 | EXPORT_SYMBOL_GPL(vfs_kern_mount); |
| 1152 | |
Eric W. Biederman | 93faccbb | 2017-02-01 06:06:16 +1300 | [diff] [blame] | 1153 | struct vfsmount * |
| 1154 | vfs_submount(const struct dentry *mountpoint, struct file_system_type *type, |
| 1155 | const char *name, void *data) |
| 1156 | { |
| 1157 | /* Until it is worked out how to pass the user namespace |
| 1158 | * through from the parent mount to the submount don't support |
| 1159 | * unprivileged mounts with submounts. |
| 1160 | */ |
| 1161 | if (mountpoint->d_sb->s_user_ns != &init_user_ns) |
| 1162 | return ERR_PTR(-EPERM); |
| 1163 | |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 1164 | return vfs_kern_mount(type, SB_SUBMOUNT, name, data); |
Eric W. Biederman | 93faccbb | 2017-02-01 06:06:16 +1300 | [diff] [blame] | 1165 | } |
| 1166 | EXPORT_SYMBOL_GPL(vfs_submount); |
| 1167 | |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1168 | static struct mount *clone_mnt(struct mount *old, struct dentry *root, |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1169 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1170 | { |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1171 | struct super_block *sb = old->mnt.mnt_sb; |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1172 | struct mount *mnt; |
| 1173 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1174 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1175 | mnt = alloc_vfsmnt(old->mnt_devname); |
| 1176 | if (!mnt) |
| 1177 | return ERR_PTR(-ENOMEM); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1178 | |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 1179 | if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE)) |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1180 | mnt->mnt_group_id = 0; /* not a peer of original */ |
| 1181 | else |
| 1182 | mnt->mnt_group_id = old->mnt_group_id; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1183 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1184 | if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { |
| 1185 | err = mnt_alloc_group_id(mnt); |
| 1186 | if (err) |
| 1187 | goto out_free; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1188 | } |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1189 | |
Al Viro | 16a34ad | 2018-04-19 22:03:08 -0400 | [diff] [blame] | 1190 | mnt->mnt.mnt_flags = old->mnt.mnt_flags; |
| 1191 | mnt->mnt.mnt_flags &= ~(MNT_WRITE_HOLD|MNT_MARKED|MNT_INTERNAL); |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 1192 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1193 | atomic_inc(&sb->s_active); |
Christian Brauner | 256c8ae | 2022-10-26 12:51:27 +0200 | [diff] [blame] | 1194 | mnt->mnt.mnt_idmap = mnt_idmap_get(mnt_idmap(&old->mnt)); |
| 1195 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1196 | mnt->mnt.mnt_sb = sb; |
| 1197 | mnt->mnt.mnt_root = dget(root); |
| 1198 | mnt->mnt_mountpoint = mnt->mnt.mnt_root; |
| 1199 | mnt->mnt_parent = mnt; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1200 | lock_mount_hash(); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1201 | list_add_tail(&mnt->mnt_instance, &sb->s_mounts); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1202 | unlock_mount_hash(); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1203 | |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 1204 | if ((flag & CL_SLAVE) || |
| 1205 | ((flag & CL_SHARED_TO_SLAVE) && IS_MNT_SHARED(old))) { |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1206 | list_add(&mnt->mnt_slave, &old->mnt_slave_list); |
| 1207 | mnt->mnt_master = old; |
| 1208 | CLEAR_MNT_SHARED(mnt); |
| 1209 | } else if (!(flag & CL_PRIVATE)) { |
| 1210 | if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old)) |
| 1211 | list_add(&mnt->mnt_share, &old->mnt_share); |
| 1212 | if (IS_MNT_SLAVE(old)) |
| 1213 | list_add(&mnt->mnt_slave, &old->mnt_slave); |
| 1214 | mnt->mnt_master = old->mnt_master; |
Al Viro | 5235d44 | 2016-11-20 19:33:09 -0500 | [diff] [blame] | 1215 | } else { |
| 1216 | CLEAR_MNT_SHARED(mnt); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1217 | } |
| 1218 | if (flag & CL_MAKE_SHARED) |
| 1219 | set_mnt_shared(mnt); |
| 1220 | |
| 1221 | /* stick the duplicate mount on the same expiry list |
| 1222 | * as the original if that was on one */ |
| 1223 | if (flag & CL_EXPIRE) { |
| 1224 | if (!list_empty(&old->mnt_expire)) |
| 1225 | list_add(&mnt->mnt_expire, &old->mnt_expire); |
| 1226 | } |
| 1227 | |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 1228 | return mnt; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1229 | |
| 1230 | out_free: |
David Howells | 8ffcb32 | 2014-01-24 12:17:54 +0000 | [diff] [blame] | 1231 | mnt_free_id(mnt); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 1232 | free_vfsmnt(mnt); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1233 | return ERR_PTR(err); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1234 | } |
| 1235 | |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1236 | static void cleanup_mnt(struct mount *mnt) |
| 1237 | { |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1238 | struct hlist_node *p; |
| 1239 | struct mount *m; |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1240 | /* |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1241 | * The warning here probably indicates that somebody messed |
| 1242 | * up a mnt_want/drop_write() pair. If this happens, the |
| 1243 | * filesystem was probably unable to make r/w->r/o transitions. |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1244 | * The locking used to deal with mnt_count decrement provides barriers, |
| 1245 | * so mnt_get_writers() below is safe. |
| 1246 | */ |
| 1247 | WARN_ON(mnt_get_writers(mnt)); |
| 1248 | if (unlikely(mnt->mnt_pins.first)) |
| 1249 | mnt_pin_kill(mnt); |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1250 | hlist_for_each_entry_safe(m, p, &mnt->mnt_stuck_children, mnt_umount) { |
| 1251 | hlist_del(&m->mnt_umount); |
| 1252 | mntput(&m->mnt); |
| 1253 | } |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1254 | fsnotify_vfsmount_delete(&mnt->mnt); |
| 1255 | dput(mnt->mnt.mnt_root); |
| 1256 | deactivate_super(mnt->mnt.mnt_sb); |
| 1257 | mnt_free_id(mnt); |
| 1258 | call_rcu(&mnt->mnt_rcu, delayed_free_vfsmnt); |
| 1259 | } |
| 1260 | |
| 1261 | static void __cleanup_mnt(struct rcu_head *head) |
| 1262 | { |
| 1263 | cleanup_mnt(container_of(head, struct mount, mnt_rcu)); |
| 1264 | } |
| 1265 | |
| 1266 | static LLIST_HEAD(delayed_mntput_list); |
| 1267 | static void delayed_mntput(struct work_struct *unused) |
| 1268 | { |
| 1269 | struct llist_node *node = llist_del_all(&delayed_mntput_list); |
Byungchul Park | 2978573 | 2017-08-07 17:44:45 +0900 | [diff] [blame] | 1270 | struct mount *m, *t; |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1271 | |
Byungchul Park | 2978573 | 2017-08-07 17:44:45 +0900 | [diff] [blame] | 1272 | llist_for_each_entry_safe(m, t, node, mnt_llist) |
| 1273 | cleanup_mnt(m); |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1274 | } |
| 1275 | static DECLARE_DELAYED_WORK(delayed_mntput_work, delayed_mntput); |
| 1276 | |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1277 | static void mntput_no_expire(struct mount *mnt) |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1278 | { |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1279 | LIST_HEAD(list); |
Eric Biggers | edf7ddb | 2020-10-31 21:40:21 -0700 | [diff] [blame] | 1280 | int count; |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1281 | |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1282 | rcu_read_lock(); |
Al Viro | 9ea0a46 | 2018-08-09 17:21:17 -0400 | [diff] [blame] | 1283 | if (likely(READ_ONCE(mnt->mnt_ns))) { |
| 1284 | /* |
| 1285 | * Since we don't do lock_mount_hash() here, |
| 1286 | * ->mnt_ns can change under us. However, if it's |
| 1287 | * non-NULL, then there's a reference that won't |
| 1288 | * be dropped until after an RCU delay done after |
| 1289 | * turning ->mnt_ns NULL. So if we observe it |
| 1290 | * non-NULL under rcu_read_lock(), the reference |
| 1291 | * we are dropping is not the final one. |
| 1292 | */ |
| 1293 | mnt_add_count(mnt, -1); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1294 | rcu_read_unlock(); |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 1295 | return; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1296 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1297 | lock_mount_hash(); |
Al Viro | 119e1ef | 2018-08-09 17:51:32 -0400 | [diff] [blame] | 1298 | /* |
| 1299 | * make sure that if __legitimize_mnt() has not seen us grab |
| 1300 | * mount_lock, we'll see their refcount increment here. |
| 1301 | */ |
| 1302 | smp_mb(); |
Al Viro | 9ea0a46 | 2018-08-09 17:21:17 -0400 | [diff] [blame] | 1303 | mnt_add_count(mnt, -1); |
Eric Biggers | edf7ddb | 2020-10-31 21:40:21 -0700 | [diff] [blame] | 1304 | count = mnt_get_count(mnt); |
| 1305 | if (count != 0) { |
| 1306 | WARN_ON(count < 0); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1307 | rcu_read_unlock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1308 | unlock_mount_hash(); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1309 | return; |
| 1310 | } |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1311 | if (unlikely(mnt->mnt.mnt_flags & MNT_DOOMED)) { |
| 1312 | rcu_read_unlock(); |
| 1313 | unlock_mount_hash(); |
| 1314 | return; |
| 1315 | } |
| 1316 | mnt->mnt.mnt_flags |= MNT_DOOMED; |
| 1317 | rcu_read_unlock(); |
Andi Kleen | 962830d | 2012-05-08 13:32:02 +0930 | [diff] [blame] | 1318 | |
Miklos Szeredi | 39f7c4d | 2011-11-21 12:11:30 +0100 | [diff] [blame] | 1319 | list_del(&mnt->mnt_instance); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1320 | |
| 1321 | if (unlikely(!list_empty(&mnt->mnt_mounts))) { |
| 1322 | struct mount *p, *tmp; |
| 1323 | list_for_each_entry_safe(p, tmp, &mnt->mnt_mounts, mnt_child) { |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1324 | __put_mountpoint(unhash_mnt(p), &list); |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1325 | hlist_add_head(&p->mnt_umount, &mnt->mnt_stuck_children); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1326 | } |
| 1327 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1328 | unlock_mount_hash(); |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1329 | shrink_dentry_list(&list); |
Al Viro | 649a795 | 2013-09-28 12:41:25 -0400 | [diff] [blame] | 1330 | |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1331 | if (likely(!(mnt->mnt.mnt_flags & MNT_INTERNAL))) { |
| 1332 | struct task_struct *task = current; |
| 1333 | if (likely(!(task->flags & PF_KTHREAD))) { |
| 1334 | init_task_work(&mnt->mnt_rcu, __cleanup_mnt); |
Jens Axboe | 91989c7 | 2020-10-16 09:02:26 -0600 | [diff] [blame] | 1335 | if (!task_work_add(task, &mnt->mnt_rcu, TWA_RESUME)) |
Al Viro | 9ea459e1 | 2014-08-08 13:08:20 -0400 | [diff] [blame] | 1336 | return; |
| 1337 | } |
| 1338 | if (llist_add(&mnt->mnt_llist, &delayed_mntput_list)) |
| 1339 | schedule_delayed_work(&delayed_mntput_work, 1); |
| 1340 | return; |
| 1341 | } |
| 1342 | cleanup_mnt(mnt); |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1343 | } |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1344 | |
| 1345 | void mntput(struct vfsmount *mnt) |
| 1346 | { |
| 1347 | if (mnt) { |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1348 | struct mount *m = real_mount(mnt); |
Mateusz Guzik | 6c4d1c9 | 2023-10-04 13:19:16 +0200 | [diff] [blame] | 1349 | /* avoid cacheline pingpong */ |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1350 | if (unlikely(m->mnt_expiry_mark)) |
Mateusz Guzik | 6c4d1c9 | 2023-10-04 13:19:16 +0200 | [diff] [blame] | 1351 | WRITE_ONCE(m->mnt_expiry_mark, 0); |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1352 | mntput_no_expire(m); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1353 | } |
| 1354 | } |
| 1355 | EXPORT_SYMBOL(mntput); |
| 1356 | |
| 1357 | struct vfsmount *mntget(struct vfsmount *mnt) |
| 1358 | { |
| 1359 | if (mnt) |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1360 | mnt_add_count(real_mount(mnt), 1); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1361 | return mnt; |
| 1362 | } |
| 1363 | EXPORT_SYMBOL(mntget); |
| 1364 | |
Rik van Riel | da27f79 | 2023-01-27 13:46:51 -0500 | [diff] [blame] | 1365 | /* |
| 1366 | * Make a mount point inaccessible to new lookups. |
| 1367 | * Because there may still be current users, the caller MUST WAIT |
| 1368 | * for an RCU grace period before destroying the mount point. |
| 1369 | */ |
| 1370 | void mnt_make_shortterm(struct vfsmount *mnt) |
| 1371 | { |
| 1372 | if (mnt) |
| 1373 | real_mount(mnt)->mnt_ns = NULL; |
| 1374 | } |
| 1375 | |
Randy Dunlap | 1f287bc | 2021-03-17 19:52:25 -0700 | [diff] [blame] | 1376 | /** |
| 1377 | * path_is_mountpoint() - Check if path is a mount in the current namespace. |
| 1378 | * @path: path to check |
Ian Kent | c6609c0 | 2016-11-24 08:03:41 +1100 | [diff] [blame] | 1379 | * |
| 1380 | * d_mountpoint() can only be used reliably to establish if a dentry is |
| 1381 | * not mounted in any namespace and that common case is handled inline. |
| 1382 | * d_mountpoint() isn't aware of the possibility there may be multiple |
| 1383 | * mounts using a given dentry in a different namespace. This function |
| 1384 | * checks if the passed in path is a mountpoint rather than the dentry |
| 1385 | * alone. |
| 1386 | */ |
| 1387 | bool path_is_mountpoint(const struct path *path) |
| 1388 | { |
| 1389 | unsigned seq; |
| 1390 | bool res; |
| 1391 | |
| 1392 | if (!d_mountpoint(path->dentry)) |
| 1393 | return false; |
| 1394 | |
| 1395 | rcu_read_lock(); |
| 1396 | do { |
| 1397 | seq = read_seqbegin(&mount_lock); |
| 1398 | res = __path_is_mountpoint(path); |
| 1399 | } while (read_seqretry(&mount_lock, seq)); |
| 1400 | rcu_read_unlock(); |
| 1401 | |
| 1402 | return res; |
| 1403 | } |
| 1404 | EXPORT_SYMBOL(path_is_mountpoint); |
| 1405 | |
Al Viro | ca71cf7 | 2016-11-20 19:45:28 -0500 | [diff] [blame] | 1406 | struct vfsmount *mnt_clone_internal(const struct path *path) |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1407 | { |
Al Viro | 3064c35 | 2014-08-07 09:12:31 -0400 | [diff] [blame] | 1408 | struct mount *p; |
| 1409 | p = clone_mnt(real_mount(path->mnt), path->dentry, CL_PRIVATE); |
| 1410 | if (IS_ERR(p)) |
| 1411 | return ERR_CAST(p); |
| 1412 | p->mnt.mnt_flags |= MNT_INTERNAL; |
| 1413 | return &p->mnt; |
Al Viro | 7b7b1ac | 2005-11-07 17:13:39 -0500 | [diff] [blame] | 1414 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1415 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1416 | #ifdef CONFIG_PROC_FS |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1417 | static struct mount *mnt_list_next(struct mnt_namespace *ns, |
| 1418 | struct list_head *p) |
| 1419 | { |
| 1420 | struct mount *mnt, *ret = NULL; |
| 1421 | |
| 1422 | lock_ns_list(ns); |
| 1423 | list_for_each_continue(p, &ns->list) { |
| 1424 | mnt = list_entry(p, typeof(*mnt), mnt_list); |
| 1425 | if (!mnt_is_cursor(mnt)) { |
| 1426 | ret = mnt; |
| 1427 | break; |
| 1428 | } |
| 1429 | } |
| 1430 | unlock_ns_list(ns); |
| 1431 | |
| 1432 | return ret; |
| 1433 | } |
| 1434 | |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1435 | /* iterator; we want it to have access to namespace_sem, thus here... */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1436 | static void *m_start(struct seq_file *m, loff_t *pos) |
| 1437 | { |
Yann Droneaud | ede1bf0 | 2015-06-30 14:57:30 -0700 | [diff] [blame] | 1438 | struct proc_mounts *p = m->private; |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1439 | struct list_head *prev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1440 | |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1441 | down_read(&namespace_sem); |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1442 | if (!*pos) { |
| 1443 | prev = &p->ns->list; |
| 1444 | } else { |
| 1445 | prev = &p->cursor.mnt_list; |
| 1446 | |
| 1447 | /* Read after we'd reached the end? */ |
| 1448 | if (list_empty(prev)) |
| 1449 | return NULL; |
Al Viro | c7999c3 | 2014-02-27 14:40:10 -0500 | [diff] [blame] | 1450 | } |
| 1451 | |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1452 | return mnt_list_next(p->ns, prev); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1453 | } |
| 1454 | |
| 1455 | static void *m_next(struct seq_file *m, void *v, loff_t *pos) |
| 1456 | { |
Yann Droneaud | ede1bf0 | 2015-06-30 14:57:30 -0700 | [diff] [blame] | 1457 | struct proc_mounts *p = m->private; |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1458 | struct mount *mnt = v; |
Pavel Emelianov | b0765fb | 2007-07-15 23:39:55 -0700 | [diff] [blame] | 1459 | |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1460 | ++*pos; |
| 1461 | return mnt_list_next(p->ns, &mnt->mnt_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1462 | } |
| 1463 | |
| 1464 | static void m_stop(struct seq_file *m, void *v) |
| 1465 | { |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1466 | struct proc_mounts *p = m->private; |
| 1467 | struct mount *mnt = v; |
| 1468 | |
| 1469 | lock_ns_list(p->ns); |
| 1470 | if (mnt) |
| 1471 | list_move_tail(&p->cursor.mnt_list, &mnt->mnt_list); |
| 1472 | else |
| 1473 | list_del_init(&p->cursor.mnt_list); |
| 1474 | unlock_ns_list(p->ns); |
Ram Pai | 390c684 | 2005-11-07 17:17:51 -0500 | [diff] [blame] | 1475 | up_read(&namespace_sem); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1476 | } |
| 1477 | |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1478 | static int m_show(struct seq_file *m, void *v) |
Al Viro | 9f5596a | 2010-02-05 00:40:25 -0500 | [diff] [blame] | 1479 | { |
Yann Droneaud | ede1bf0 | 2015-06-30 14:57:30 -0700 | [diff] [blame] | 1480 | struct proc_mounts *p = m->private; |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1481 | struct mount *r = v; |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1482 | return p->show(m, &r->mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1483 | } |
| 1484 | |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1485 | const struct seq_operations mounts_op = { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1486 | .start = m_start, |
| 1487 | .next = m_next, |
| 1488 | .stop = m_stop, |
Al Viro | 0226f49 | 2011-12-06 12:21:54 -0500 | [diff] [blame] | 1489 | .show = m_show, |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1490 | }; |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 1491 | |
| 1492 | void mnt_cursor_del(struct mnt_namespace *ns, struct mount *cursor) |
| 1493 | { |
| 1494 | down_read(&namespace_sem); |
| 1495 | lock_ns_list(ns); |
| 1496 | list_del(&cursor->mnt_list); |
| 1497 | unlock_ns_list(ns); |
| 1498 | up_read(&namespace_sem); |
| 1499 | } |
Miklos Szeredi | a1a2c40 | 2008-03-27 13:06:24 +0100 | [diff] [blame] | 1500 | #endif /* CONFIG_PROC_FS */ |
Chuck Lever | b4629fe | 2006-03-20 13:44:12 -0500 | [diff] [blame] | 1501 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1502 | /** |
| 1503 | * may_umount_tree - check if a mount tree is busy |
Randy Dunlap | 1f287bc | 2021-03-17 19:52:25 -0700 | [diff] [blame] | 1504 | * @m: root of mount tree |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1505 | * |
| 1506 | * This is called to check if a tree of mounts has any |
| 1507 | * open files, pwds, chroots or sub mounts that are |
| 1508 | * busy. |
| 1509 | */ |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1510 | int may_umount_tree(struct vfsmount *m) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1511 | { |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1512 | struct mount *mnt = real_mount(m); |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1513 | int actual_refs = 0; |
| 1514 | int minimum_refs = 0; |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1515 | struct mount *p; |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1516 | BUG_ON(!m); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1517 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1518 | /* write lock needed for mnt_get_count */ |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1519 | lock_mount_hash(); |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1520 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1521 | actual_refs += mnt_get_count(p); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1522 | minimum_refs += 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1523 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1524 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1525 | |
| 1526 | if (actual_refs > minimum_refs) |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1527 | return 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1528 | |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1529 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1530 | } |
| 1531 | |
| 1532 | EXPORT_SYMBOL(may_umount_tree); |
| 1533 | |
| 1534 | /** |
| 1535 | * may_umount - check if a mount point is busy |
| 1536 | * @mnt: root of mount |
| 1537 | * |
| 1538 | * This is called to check if a mount point has any |
| 1539 | * open files, pwds, chroots or sub mounts. If the |
| 1540 | * mount has sub mounts this will return busy |
| 1541 | * regardless of whether the sub mounts are busy. |
| 1542 | * |
| 1543 | * Doesn't take quota and stuff into account. IOW, in some cases it will |
| 1544 | * give false negatives. The main reason why it's here is that we need |
| 1545 | * a non-destructive way to look for easily umountable filesystems. |
| 1546 | */ |
| 1547 | int may_umount(struct vfsmount *mnt) |
| 1548 | { |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1549 | int ret = 1; |
Al Viro | 8ad08d8 | 2010-01-16 12:56:08 -0500 | [diff] [blame] | 1550 | down_read(&namespace_sem); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1551 | lock_mount_hash(); |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1552 | if (propagate_mount_busy(real_mount(mnt), 2)) |
Ian Kent | e3474a8 | 2006-03-27 01:14:51 -0800 | [diff] [blame] | 1553 | ret = 0; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1554 | unlock_mount_hash(); |
Al Viro | 8ad08d8 | 2010-01-16 12:56:08 -0500 | [diff] [blame] | 1555 | up_read(&namespace_sem); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1556 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1557 | } |
| 1558 | |
| 1559 | EXPORT_SYMBOL(may_umount); |
| 1560 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1561 | static void namespace_unlock(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1562 | { |
Eric W. Biederman | a3b3c56 | 2015-04-02 20:33:53 -0500 | [diff] [blame] | 1563 | struct hlist_head head; |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1564 | struct hlist_node *p; |
| 1565 | struct mount *m; |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1566 | LIST_HEAD(list); |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1567 | |
Eric W. Biederman | a3b3c56 | 2015-04-02 20:33:53 -0500 | [diff] [blame] | 1568 | hlist_move_list(&unmounted, &head); |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1569 | list_splice_init(&ex_mountpoints, &list); |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1570 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1571 | up_write(&namespace_sem); |
| 1572 | |
Al Viro | 4edbe13 | 2019-06-30 10:39:08 -0400 | [diff] [blame] | 1573 | shrink_dentry_list(&list); |
| 1574 | |
Eric W. Biederman | a3b3c56 | 2015-04-02 20:33:53 -0500 | [diff] [blame] | 1575 | if (likely(hlist_empty(&head))) |
| 1576 | return; |
| 1577 | |
NeilBrown | 22cb740 | 2018-11-30 10:33:18 +1100 | [diff] [blame] | 1578 | synchronize_rcu_expedited(); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1579 | |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1580 | hlist_for_each_entry_safe(m, p, &head, mnt_umount) { |
| 1581 | hlist_del(&m->mnt_umount); |
| 1582 | mntput(&m->mnt); |
| 1583 | } |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1584 | } |
| 1585 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1586 | static inline void namespace_lock(void) |
Al Viro | e3197d8 | 2013-03-16 14:35:16 -0400 | [diff] [blame] | 1587 | { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1588 | down_write(&namespace_sem); |
Al Viro | e3197d8 | 2013-03-16 14:35:16 -0400 | [diff] [blame] | 1589 | } |
| 1590 | |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1591 | enum umount_tree_flags { |
| 1592 | UMOUNT_SYNC = 1, |
| 1593 | UMOUNT_PROPAGATE = 2, |
Eric W. Biederman | e0c9c0a | 2015-04-01 18:30:06 -0500 | [diff] [blame] | 1594 | UMOUNT_CONNECTED = 4, |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1595 | }; |
Eric W. Biederman | f2d0a12 | 2015-07-17 14:15:30 -0500 | [diff] [blame] | 1596 | |
| 1597 | static bool disconnect_mount(struct mount *mnt, enum umount_tree_flags how) |
| 1598 | { |
| 1599 | /* Leaving mounts connected is only valid for lazy umounts */ |
| 1600 | if (how & UMOUNT_SYNC) |
| 1601 | return true; |
| 1602 | |
| 1603 | /* A mount without a parent has nothing to be connected to */ |
| 1604 | if (!mnt_has_parent(mnt)) |
| 1605 | return true; |
| 1606 | |
| 1607 | /* Because the reference counting rules change when mounts are |
| 1608 | * unmounted and connected, umounted mounts may not be |
| 1609 | * connected to mounted mounts. |
| 1610 | */ |
| 1611 | if (!(mnt->mnt_parent->mnt.mnt_flags & MNT_UMOUNT)) |
| 1612 | return true; |
| 1613 | |
| 1614 | /* Has it been requested that the mount remain connected? */ |
| 1615 | if (how & UMOUNT_CONNECTED) |
| 1616 | return false; |
| 1617 | |
| 1618 | /* Is the mount locked such that it needs to remain connected? */ |
| 1619 | if (IS_MNT_LOCKED(mnt)) |
| 1620 | return false; |
| 1621 | |
| 1622 | /* By default disconnect the mount */ |
| 1623 | return true; |
| 1624 | } |
| 1625 | |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1626 | /* |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1627 | * mount_lock must be held |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 1628 | * namespace_sem must be held for write |
| 1629 | */ |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1630 | static void umount_tree(struct mount *mnt, enum umount_tree_flags how) |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1631 | { |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1632 | LIST_HEAD(tmp_list); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1633 | struct mount *p; |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1634 | |
Eric W. Biederman | 5d88457 | 2015-01-03 05:39:35 -0600 | [diff] [blame] | 1635 | if (how & UMOUNT_PROPAGATE) |
| 1636 | propagate_mount_unlock(mnt); |
| 1637 | |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1638 | /* Gather the mounts to umount */ |
Eric W. Biederman | 590ce4bc | 2014-12-22 18:30:08 -0600 | [diff] [blame] | 1639 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 1640 | p->mnt.mnt_flags |= MNT_UMOUNT; |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1641 | list_move(&p->mnt_list, &tmp_list); |
Eric W. Biederman | 590ce4bc | 2014-12-22 18:30:08 -0600 | [diff] [blame] | 1642 | } |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1643 | |
Eric W. Biederman | 411a938 | 2014-12-22 19:12:07 -0600 | [diff] [blame] | 1644 | /* Hide the mounts from mnt_mounts */ |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1645 | list_for_each_entry(p, &tmp_list, mnt_list) { |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1646 | list_del_init(&p->mnt_child); |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 1647 | } |
Ram Pai | 70fbcdf | 2005-11-07 17:17:04 -0500 | [diff] [blame] | 1648 | |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1649 | /* Add propogated mounts to the tmp_list */ |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1650 | if (how & UMOUNT_PROPAGATE) |
Al Viro | 7b8a53f | 2011-01-15 20:08:44 -0500 | [diff] [blame] | 1651 | propagate_umount(&tmp_list); |
Ram Pai | a05964f | 2005-11-07 17:20:17 -0500 | [diff] [blame] | 1652 | |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1653 | while (!list_empty(&tmp_list)) { |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 1654 | struct mnt_namespace *ns; |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1655 | bool disconnect; |
Eric W. Biederman | c003b26 | 2014-12-18 13:10:48 -0600 | [diff] [blame] | 1656 | p = list_first_entry(&tmp_list, struct mount, mnt_list); |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 1657 | list_del_init(&p->mnt_expire); |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1658 | list_del_init(&p->mnt_list); |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 1659 | ns = p->mnt_ns; |
| 1660 | if (ns) { |
| 1661 | ns->mounts--; |
| 1662 | __touch_mnt_namespace(ns); |
| 1663 | } |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1664 | p->mnt_ns = NULL; |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1665 | if (how & UMOUNT_SYNC) |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1666 | p->mnt.mnt_flags |= MNT_SYNC_UMOUNT; |
Al Viro | 87b95ce | 2015-01-10 19:01:08 -0500 | [diff] [blame] | 1667 | |
Eric W. Biederman | f2d0a12 | 2015-07-17 14:15:30 -0500 | [diff] [blame] | 1668 | disconnect = disconnect_mount(p, how); |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 1669 | if (mnt_has_parent(p)) { |
Al Viro | 81b6b06 | 2014-08-30 18:32:05 -0400 | [diff] [blame] | 1670 | mnt_add_count(p->mnt_parent, -1); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1671 | if (!disconnect) { |
| 1672 | /* Don't forget about p */ |
| 1673 | list_add_tail(&p->mnt_child, &p->mnt_parent->mnt_mounts); |
| 1674 | } else { |
| 1675 | umount_mnt(p); |
| 1676 | } |
Al Viro | 7c4b93d | 2008-03-21 23:59:49 -0400 | [diff] [blame] | 1677 | } |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 1678 | change_mnt_propagation(p, MS_PRIVATE); |
Al Viro | 19a1c40 | 2019-07-24 12:45:46 -0400 | [diff] [blame] | 1679 | if (disconnect) |
| 1680 | hlist_add_head(&p->mnt_umount, &unmounted); |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 1681 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1682 | } |
| 1683 | |
Al Viro | b54b9be | 2013-03-16 14:39:34 -0400 | [diff] [blame] | 1684 | static void shrink_submounts(struct mount *mnt); |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 1685 | |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 1686 | static int do_umount_root(struct super_block *sb) |
| 1687 | { |
| 1688 | int ret = 0; |
| 1689 | |
| 1690 | down_write(&sb->s_umount); |
| 1691 | if (!sb_rdonly(sb)) { |
| 1692 | struct fs_context *fc; |
| 1693 | |
| 1694 | fc = fs_context_for_reconfigure(sb->s_root, SB_RDONLY, |
| 1695 | SB_RDONLY); |
| 1696 | if (IS_ERR(fc)) { |
| 1697 | ret = PTR_ERR(fc); |
| 1698 | } else { |
| 1699 | ret = parse_monolithic_mount_data(fc, NULL); |
| 1700 | if (!ret) |
| 1701 | ret = reconfigure_super(fc); |
| 1702 | put_fs_context(fc); |
| 1703 | } |
| 1704 | } |
| 1705 | up_write(&sb->s_umount); |
| 1706 | return ret; |
| 1707 | } |
| 1708 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1709 | static int do_umount(struct mount *mnt, int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1710 | { |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1711 | struct super_block *sb = mnt->mnt.mnt_sb; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1712 | int retval; |
| 1713 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1714 | retval = security_sb_umount(&mnt->mnt, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1715 | if (retval) |
| 1716 | return retval; |
| 1717 | |
| 1718 | /* |
| 1719 | * Allow userspace to request a mountpoint be expired rather than |
| 1720 | * unmounting unconditionally. Unmount only happens if: |
| 1721 | * (1) the mark is already set (the mark is cleared by mntput()) |
| 1722 | * (2) the usage count == 1 [parent vfsmount] + 1 [sys_umount] |
| 1723 | */ |
| 1724 | if (flags & MNT_EXPIRE) { |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1725 | if (&mnt->mnt == current->fs->root.mnt || |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1726 | flags & (MNT_FORCE | MNT_DETACH)) |
| 1727 | return -EINVAL; |
| 1728 | |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1729 | /* |
| 1730 | * probably don't strictly need the lock here if we examined |
| 1731 | * all race cases, but it's a slowpath. |
| 1732 | */ |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1733 | lock_mount_hash(); |
Al Viro | 83adc75 | 2011-11-24 22:37:54 -0500 | [diff] [blame] | 1734 | if (mnt_get_count(mnt) != 2) { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1735 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1736 | return -EBUSY; |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 1737 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1738 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1739 | |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 1740 | if (!xchg(&mnt->mnt_expiry_mark, 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1741 | return -EAGAIN; |
| 1742 | } |
| 1743 | |
| 1744 | /* |
| 1745 | * If we may have to abort operations to get out of this |
| 1746 | * mount, and they will themselves hold resources we must |
| 1747 | * allow the fs to do things. In the Unix tradition of |
| 1748 | * 'Gee thats tricky lets do it in userspace' the umount_begin |
| 1749 | * might fail to complete on the first run through as other tasks |
| 1750 | * must return, and the like. Thats for the mount program to worry |
| 1751 | * about for the moment. |
| 1752 | */ |
| 1753 | |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1754 | if (flags & MNT_FORCE && sb->s_op->umount_begin) { |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1755 | sb->s_op->umount_begin(sb); |
Al Viro | 42faad9 | 2008-04-24 07:21:56 -0400 | [diff] [blame] | 1756 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1757 | |
| 1758 | /* |
| 1759 | * No sense to grab the lock for this test, but test itself looks |
| 1760 | * somewhat bogus. Suggestions for better replacement? |
| 1761 | * Ho-hum... In principle, we might treat that as umount + switch |
| 1762 | * to rootfs. GC would eventually take care of the old vfsmount. |
| 1763 | * Actually it makes sense, especially if rootfs would contain a |
| 1764 | * /reboot - static binary that would close all descriptors and |
| 1765 | * call reboot(9). Then init(8) could umount root and exec /reboot. |
| 1766 | */ |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 1767 | if (&mnt->mnt == current->fs->root.mnt && !(flags & MNT_DETACH)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1768 | /* |
| 1769 | * Special case for "unmounting" root ... |
| 1770 | * we just try to remount it readonly. |
| 1771 | */ |
Eric W. Biederman | bc6155d | 2017-09-18 17:58:08 -0500 | [diff] [blame] | 1772 | if (!ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) |
Andy Lutomirski | a1480dc | 2014-10-08 12:32:47 -0700 | [diff] [blame] | 1773 | return -EPERM; |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 1774 | return do_umount_root(sb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1775 | } |
| 1776 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 1777 | namespace_lock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1778 | lock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1779 | |
Eric W. Biederman | 25d202e | 2018-10-22 10:21:38 -0500 | [diff] [blame] | 1780 | /* Recheck MNT_LOCKED with the locks held */ |
| 1781 | retval = -EINVAL; |
| 1782 | if (mnt->mnt.mnt_flags & MNT_LOCKED) |
| 1783 | goto out; |
| 1784 | |
| 1785 | event++; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1786 | if (flags & MNT_DETACH) { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 1787 | if (!list_empty(&mnt->mnt_list)) |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1788 | umount_tree(mnt, UMOUNT_PROPAGATE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1789 | retval = 0; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1790 | } else { |
| 1791 | shrink_submounts(mnt); |
| 1792 | retval = -EBUSY; |
| 1793 | if (!propagate_mount_busy(mnt, 2)) { |
| 1794 | if (!list_empty(&mnt->mnt_list)) |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 1795 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 1796 | retval = 0; |
| 1797 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1798 | } |
Eric W. Biederman | 25d202e | 2018-10-22 10:21:38 -0500 | [diff] [blame] | 1799 | out: |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 1800 | unlock_mount_hash(); |
Al Viro | e3197d8 | 2013-03-16 14:35:16 -0400 | [diff] [blame] | 1801 | namespace_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1802 | return retval; |
| 1803 | } |
| 1804 | |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1805 | /* |
| 1806 | * __detach_mounts - lazily unmount all mounts on the specified dentry |
| 1807 | * |
| 1808 | * During unlink, rmdir, and d_drop it is possible to loose the path |
| 1809 | * to an existing mountpoint, and wind up leaking the mount. |
| 1810 | * detach_mounts allows lazily unmounting those mounts instead of |
| 1811 | * leaking them. |
| 1812 | * |
| 1813 | * The caller may hold dentry->d_inode->i_mutex. |
| 1814 | */ |
| 1815 | void __detach_mounts(struct dentry *dentry) |
| 1816 | { |
| 1817 | struct mountpoint *mp; |
| 1818 | struct mount *mnt; |
| 1819 | |
| 1820 | namespace_lock(); |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 1821 | lock_mount_hash(); |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1822 | mp = lookup_mountpoint(dentry); |
Al Viro | adc9b5c | 2019-06-29 12:06:51 -0400 | [diff] [blame] | 1823 | if (!mp) |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1824 | goto out_unlock; |
| 1825 | |
Andrey Ulanov | e06b933 | 2016-04-15 14:24:41 -0700 | [diff] [blame] | 1826 | event++; |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1827 | while (!hlist_empty(&mp->m_list)) { |
| 1828 | mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1829 | if (mnt->mnt.mnt_flags & MNT_UMOUNT) { |
Eric W. Biederman | fe78fcc8 | 2015-07-17 14:54:27 -0500 | [diff] [blame] | 1830 | umount_mnt(mnt); |
Al Viro | 56cbb429 | 2019-07-04 16:57:51 -0400 | [diff] [blame] | 1831 | hlist_add_head(&mnt->mnt_umount, &unmounted); |
Eric W. Biederman | ce07d89 | 2014-12-23 21:37:03 -0600 | [diff] [blame] | 1832 | } |
Eric W. Biederman | e0c9c0a | 2015-04-01 18:30:06 -0500 | [diff] [blame] | 1833 | else umount_tree(mnt, UMOUNT_CONNECTED); |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1834 | } |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1835 | put_mountpoint(mp); |
| 1836 | out_unlock: |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 1837 | unlock_mount_hash(); |
Eric W. Biederman | 80b5dce | 2013-10-03 01:31:18 -0700 | [diff] [blame] | 1838 | namespace_unlock(); |
| 1839 | } |
| 1840 | |
David Howells | dd111b3 | 2017-07-04 17:25:09 +0100 | [diff] [blame] | 1841 | /* |
Al Viro | 9b40bc9 | 2013-02-22 22:45:42 -0500 | [diff] [blame] | 1842 | * Is the caller allowed to modify his namespace? |
| 1843 | */ |
Al Viro | a5f85d7 | 2022-03-01 00:05:29 -0500 | [diff] [blame] | 1844 | bool may_mount(void) |
Al Viro | 9b40bc9 | 2013-02-22 22:45:42 -0500 | [diff] [blame] | 1845 | { |
| 1846 | return ns_capable(current->nsproxy->mnt_ns->user_ns, CAP_SYS_ADMIN); |
| 1847 | } |
| 1848 | |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 1849 | /** |
| 1850 | * path_mounted - check whether path is mounted |
| 1851 | * @path: path to check |
| 1852 | * |
| 1853 | * Determine whether @path refers to the root of a mount. |
| 1854 | * |
| 1855 | * Return: true if @path is the root of a mount, false if not. |
| 1856 | */ |
| 1857 | static inline bool path_mounted(const struct path *path) |
| 1858 | { |
| 1859 | return path->mnt->mnt_root == path->dentry; |
| 1860 | } |
| 1861 | |
Jeff Layton | f7e33bd | 2021-08-19 14:56:38 -0400 | [diff] [blame] | 1862 | static void warn_mandlock(void) |
Jeff Layton | 9e8925b | 2015-11-16 09:49:34 -0500 | [diff] [blame] | 1863 | { |
Jeff Layton | f7e33bd | 2021-08-19 14:56:38 -0400 | [diff] [blame] | 1864 | pr_warn_once("=======================================================\n" |
| 1865 | "WARNING: The mand mount option has been deprecated and\n" |
| 1866 | " and is ignored by this kernel. Remove the mand\n" |
| 1867 | " option from the mount to silence this warning.\n" |
| 1868 | "=======================================================\n"); |
Jeff Layton | 9e8925b | 2015-11-16 09:49:34 -0500 | [diff] [blame] | 1869 | } |
| 1870 | |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1871 | static int can_umount(const struct path *path, int flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1872 | { |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1873 | struct mount *mnt = real_mount(path->mnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1874 | |
Al Viro | 9b40bc9 | 2013-02-22 22:45:42 -0500 | [diff] [blame] | 1875 | if (!may_mount()) |
| 1876 | return -EPERM; |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 1877 | if (!path_mounted(path)) |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1878 | return -EINVAL; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 1879 | if (!check_mnt(mnt)) |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1880 | return -EINVAL; |
Eric W. Biederman | 25d202e | 2018-10-22 10:21:38 -0500 | [diff] [blame] | 1881 | if (mnt->mnt.mnt_flags & MNT_LOCKED) /* Check optimistically */ |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1882 | return -EINVAL; |
Eric W. Biederman | b2f5d4d | 2014-10-04 14:44:03 -0700 | [diff] [blame] | 1883 | if (flags & MNT_FORCE && !capable(CAP_SYS_ADMIN)) |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1884 | return -EPERM; |
| 1885 | return 0; |
| 1886 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1887 | |
Al Viro | a0a6df9 | 2021-01-04 15:25:34 -0500 | [diff] [blame] | 1888 | // caller is responsible for flags being sane |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1889 | int path_umount(struct path *path, int flags) |
| 1890 | { |
| 1891 | struct mount *mnt = real_mount(path->mnt); |
| 1892 | int ret; |
| 1893 | |
| 1894 | ret = can_umount(path, flags); |
| 1895 | if (!ret) |
| 1896 | ret = do_umount(mnt, flags); |
| 1897 | |
Jan Blunck | 429731b | 2008-02-14 19:34:31 -0800 | [diff] [blame] | 1898 | /* we mustn't call path_put() as that would clear mnt_expiry_mark */ |
Christoph Hellwig | 41525f5 | 2020-07-21 10:54:34 +0200 | [diff] [blame] | 1899 | dput(path->dentry); |
Al Viro | 900148d | 2011-11-25 00:33:11 -0500 | [diff] [blame] | 1900 | mntput_no_expire(mnt); |
Christoph Hellwig | 25ccd24f | 2020-08-06 16:07:10 +0200 | [diff] [blame] | 1901 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1902 | } |
| 1903 | |
Christoph Hellwig | 09267de | 2020-07-23 08:23:08 +0200 | [diff] [blame] | 1904 | static int ksys_umount(char __user *name, int flags) |
Christoph Hellwig | 41525f5 | 2020-07-21 10:54:34 +0200 | [diff] [blame] | 1905 | { |
| 1906 | int lookup_flags = LOOKUP_MOUNTPOINT; |
| 1907 | struct path path; |
| 1908 | int ret; |
| 1909 | |
Al Viro | a0a6df9 | 2021-01-04 15:25:34 -0500 | [diff] [blame] | 1910 | // basic validity checks done first |
| 1911 | if (flags & ~(MNT_FORCE | MNT_DETACH | MNT_EXPIRE | UMOUNT_NOFOLLOW)) |
| 1912 | return -EINVAL; |
| 1913 | |
Christoph Hellwig | 41525f5 | 2020-07-21 10:54:34 +0200 | [diff] [blame] | 1914 | if (!(flags & UMOUNT_NOFOLLOW)) |
| 1915 | lookup_flags |= LOOKUP_FOLLOW; |
| 1916 | ret = user_path_at(AT_FDCWD, name, lookup_flags, &path); |
| 1917 | if (ret) |
| 1918 | return ret; |
| 1919 | return path_umount(&path, flags); |
| 1920 | } |
| 1921 | |
Dominik Brodowski | 3a18ef5 | 2018-03-11 11:34:40 +0100 | [diff] [blame] | 1922 | SYSCALL_DEFINE2(umount, char __user *, name, int, flags) |
| 1923 | { |
| 1924 | return ksys_umount(name, flags); |
| 1925 | } |
| 1926 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1927 | #ifdef __ARCH_WANT_SYS_OLDUMOUNT |
| 1928 | |
| 1929 | /* |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 1930 | * The 2.0 compatible umount. No flags. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1931 | */ |
Heiko Carstens | bdc480e | 2009-01-14 14:14:12 +0100 | [diff] [blame] | 1932 | SYSCALL_DEFINE1(oldumount, char __user *, name) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1933 | { |
Dominik Brodowski | 3a18ef5 | 2018-03-11 11:34:40 +0100 | [diff] [blame] | 1934 | return ksys_umount(name, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1935 | } |
| 1936 | |
| 1937 | #endif |
| 1938 | |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1939 | static bool is_mnt_ns_file(struct dentry *dentry) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 1940 | { |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1941 | /* Is this a proxy for a mount namespace? */ |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 1942 | return dentry->d_op == &ns_dentry_operations && |
| 1943 | dentry->d_fsdata == &mntns_operations; |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1944 | } |
| 1945 | |
Eric Biggers | 213921f | 2020-01-04 12:59:55 -0800 | [diff] [blame] | 1946 | static struct mnt_namespace *to_mnt_ns(struct ns_common *ns) |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 1947 | { |
| 1948 | return container_of(ns, struct mnt_namespace, ns); |
| 1949 | } |
| 1950 | |
Christian Brauner | 303cc57 | 2020-05-05 16:04:31 +0200 | [diff] [blame] | 1951 | struct ns_common *from_mnt_ns(struct mnt_namespace *mnt) |
| 1952 | { |
| 1953 | return &mnt->ns; |
| 1954 | } |
| 1955 | |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1956 | static bool mnt_ns_loop(struct dentry *dentry) |
| 1957 | { |
| 1958 | /* Could bind mounting the mount namespace inode cause a |
| 1959 | * mount namespace loop? |
| 1960 | */ |
| 1961 | struct mnt_namespace *mnt_ns; |
| 1962 | if (!is_mnt_ns_file(dentry)) |
| 1963 | return false; |
| 1964 | |
Al Viro | f77c801 | 2014-11-01 03:13:17 -0400 | [diff] [blame] | 1965 | mnt_ns = to_mnt_ns(get_proc_ns(dentry->d_inode)); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 1966 | return current->nsproxy->mnt_ns->seq >= mnt_ns->seq; |
| 1967 | } |
| 1968 | |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 1969 | struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1970 | int flag) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1971 | { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 1972 | struct mount *res, *p, *q, *r, *parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1973 | |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1974 | if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(mnt)) |
| 1975 | return ERR_PTR(-EINVAL); |
| 1976 | |
| 1977 | if (!(flag & CL_COPY_MNT_NS_FILE) && is_mnt_ns_file(dentry)) |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1978 | return ERR_PTR(-EINVAL); |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 1979 | |
Ram Pai | 36341f6 | 2005-11-07 17:17:22 -0500 | [diff] [blame] | 1980 | res = q = clone_mnt(mnt, dentry, flag); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 1981 | if (IS_ERR(q)) |
| 1982 | return q; |
| 1983 | |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 1984 | q->mnt_mountpoint = mnt->mnt_mountpoint; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1985 | |
| 1986 | p = mnt; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 1987 | list_for_each_entry(r, &mnt->mnt_mounts, mnt_child) { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 1988 | struct mount *s; |
Jan Blunck | 7ec02ef | 2008-04-29 00:59:40 -0700 | [diff] [blame] | 1989 | if (!is_subdir(r->mnt_mountpoint, dentry)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1990 | continue; |
| 1991 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 1992 | for (s = r; s; s = next_mnt(s, r)) { |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 1993 | if (!(flag & CL_COPY_UNBINDABLE) && |
| 1994 | IS_MNT_UNBINDABLE(s)) { |
Eric W. Biederman | df7342b | 2018-10-25 09:04:18 -0500 | [diff] [blame] | 1995 | if (s->mnt.mnt_flags & MNT_LOCKED) { |
| 1996 | /* Both unbindable and locked. */ |
| 1997 | q = ERR_PTR(-EPERM); |
| 1998 | goto out; |
| 1999 | } else { |
| 2000 | s = skip_mnt_tree(s); |
| 2001 | continue; |
| 2002 | } |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 2003 | } |
| 2004 | if (!(flag & CL_COPY_MNT_NS_FILE) && |
| 2005 | is_mnt_ns_file(s->mnt.mnt_root)) { |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2006 | s = skip_mnt_tree(s); |
| 2007 | continue; |
| 2008 | } |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 2009 | while (p != s->mnt_parent) { |
| 2010 | p = p->mnt_parent; |
| 2011 | q = q->mnt_parent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2012 | } |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 2013 | p = s; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2014 | parent = q; |
Al Viro | 87129cc | 2011-11-24 21:24:27 -0500 | [diff] [blame] | 2015 | q = clone_mnt(p, p->mnt.mnt_root, flag); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2016 | if (IS_ERR(q)) |
| 2017 | goto out; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2018 | lock_mount_hash(); |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2019 | list_add_tail(&q->mnt_list, &res->mnt_list); |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2020 | attach_mnt(q, parent, p->mnt_mp, false); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2021 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2022 | } |
| 2023 | } |
| 2024 | return res; |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2025 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2026 | if (res) { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2027 | lock_mount_hash(); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 2028 | umount_tree(res, UMOUNT_SYNC); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2029 | unlock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2030 | } |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2031 | return q; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2032 | } |
| 2033 | |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2034 | /* Caller should check returned pointer for errors */ |
| 2035 | |
Al Viro | ca71cf7 | 2016-11-20 19:45:28 -0500 | [diff] [blame] | 2036 | struct vfsmount *collect_mounts(const struct path *path) |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 2037 | { |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 2038 | struct mount *tree; |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2039 | namespace_lock(); |
Eric W. Biederman | cd4a401 | 2015-01-07 14:28:26 -0600 | [diff] [blame] | 2040 | if (!check_mnt(real_mount(path->mnt))) |
| 2041 | tree = ERR_PTR(-EINVAL); |
| 2042 | else |
| 2043 | tree = copy_tree(real_mount(path->mnt), path->dentry, |
| 2044 | CL_COPY_ALL | CL_PRIVATE); |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 2045 | namespace_unlock(); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2046 | if (IS_ERR(tree)) |
Dan Carpenter | 52e220d | 2013-08-14 12:44:39 +0300 | [diff] [blame] | 2047 | return ERR_CAST(tree); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2048 | return &tree->mnt; |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 2049 | } |
| 2050 | |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2051 | static void free_mnt_ns(struct mnt_namespace *); |
| 2052 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *, bool); |
| 2053 | |
| 2054 | void dissolve_on_fput(struct vfsmount *mnt) |
| 2055 | { |
| 2056 | struct mnt_namespace *ns; |
| 2057 | namespace_lock(); |
| 2058 | lock_mount_hash(); |
| 2059 | ns = real_mount(mnt)->mnt_ns; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2060 | if (ns) { |
| 2061 | if (is_anon_ns(ns)) |
| 2062 | umount_tree(real_mount(mnt), UMOUNT_CONNECTED); |
| 2063 | else |
| 2064 | ns = NULL; |
| 2065 | } |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2066 | unlock_mount_hash(); |
| 2067 | namespace_unlock(); |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2068 | if (ns) |
| 2069 | free_mnt_ns(ns); |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2070 | } |
| 2071 | |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 2072 | void drop_collected_mounts(struct vfsmount *mnt) |
| 2073 | { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2074 | namespace_lock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2075 | lock_mount_hash(); |
Eric W. Biederman | 9c8e0a1 | 2018-10-25 12:05:11 -0500 | [diff] [blame] | 2076 | umount_tree(real_mount(mnt), 0); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2077 | unlock_mount_hash(); |
Al Viro | 3ab6abe | 2013-03-16 14:42:19 -0400 | [diff] [blame] | 2078 | namespace_unlock(); |
Al Viro | 8aec080 | 2007-06-07 12:20:32 -0400 | [diff] [blame] | 2079 | } |
| 2080 | |
Miklos Szeredi | 427215d | 2021-08-09 10:19:47 +0200 | [diff] [blame] | 2081 | static bool has_locked_children(struct mount *mnt, struct dentry *dentry) |
| 2082 | { |
| 2083 | struct mount *child; |
| 2084 | |
| 2085 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { |
| 2086 | if (!is_subdir(child->mnt_mountpoint, dentry)) |
| 2087 | continue; |
| 2088 | |
| 2089 | if (child->mnt.mnt_flags & MNT_LOCKED) |
| 2090 | return true; |
| 2091 | } |
| 2092 | return false; |
| 2093 | } |
| 2094 | |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2095 | /** |
| 2096 | * clone_private_mount - create a private clone of a path |
Randy Dunlap | 1f287bc | 2021-03-17 19:52:25 -0700 | [diff] [blame] | 2097 | * @path: path to clone |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2098 | * |
Randy Dunlap | 1f287bc | 2021-03-17 19:52:25 -0700 | [diff] [blame] | 2099 | * This creates a new vfsmount, which will be the clone of @path. The new mount |
| 2100 | * will not be attached anywhere in the namespace and will be private (i.e. |
| 2101 | * changes to the originating mount won't be propagated into this). |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2102 | * |
| 2103 | * Release with mntput(). |
| 2104 | */ |
Al Viro | ca71cf7 | 2016-11-20 19:45:28 -0500 | [diff] [blame] | 2105 | struct vfsmount *clone_private_mount(const struct path *path) |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2106 | { |
| 2107 | struct mount *old_mnt = real_mount(path->mnt); |
| 2108 | struct mount *new_mnt; |
| 2109 | |
Miklos Szeredi | 427215d | 2021-08-09 10:19:47 +0200 | [diff] [blame] | 2110 | down_read(&namespace_sem); |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2111 | if (IS_MNT_UNBINDABLE(old_mnt)) |
Miklos Szeredi | 427215d | 2021-08-09 10:19:47 +0200 | [diff] [blame] | 2112 | goto invalid; |
| 2113 | |
| 2114 | if (!check_mnt(old_mnt)) |
| 2115 | goto invalid; |
| 2116 | |
| 2117 | if (has_locked_children(old_mnt, path->dentry)) |
| 2118 | goto invalid; |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2119 | |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2120 | new_mnt = clone_mnt(old_mnt, path->dentry, CL_PRIVATE); |
Miklos Szeredi | 427215d | 2021-08-09 10:19:47 +0200 | [diff] [blame] | 2121 | up_read(&namespace_sem); |
| 2122 | |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2123 | if (IS_ERR(new_mnt)) |
| 2124 | return ERR_CAST(new_mnt); |
| 2125 | |
Miklos Szeredi | df820f8 | 2020-06-04 10:48:19 +0200 | [diff] [blame] | 2126 | /* Longterm mount to be removed by kern_unmount*() */ |
| 2127 | new_mnt->mnt_ns = MNT_NS_INTERNAL; |
| 2128 | |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2129 | return &new_mnt->mnt; |
Miklos Szeredi | 427215d | 2021-08-09 10:19:47 +0200 | [diff] [blame] | 2130 | |
| 2131 | invalid: |
| 2132 | up_read(&namespace_sem); |
| 2133 | return ERR_PTR(-EINVAL); |
Miklos Szeredi | c771d68 | 2014-10-24 00:14:36 +0200 | [diff] [blame] | 2134 | } |
| 2135 | EXPORT_SYMBOL_GPL(clone_private_mount); |
| 2136 | |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 2137 | int iterate_mounts(int (*f)(struct vfsmount *, void *), void *arg, |
| 2138 | struct vfsmount *root) |
| 2139 | { |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2140 | struct mount *mnt; |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 2141 | int res = f(root, arg); |
| 2142 | if (res) |
| 2143 | return res; |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 2144 | list_for_each_entry(mnt, &real_mount(root)->mnt_list, mnt_list) { |
| 2145 | res = f(&mnt->mnt, arg); |
Al Viro | 1f70713 | 2010-01-30 22:51:25 -0500 | [diff] [blame] | 2146 | if (res) |
| 2147 | return res; |
| 2148 | } |
| 2149 | return 0; |
| 2150 | } |
| 2151 | |
Al Viro | 3bd045c | 2019-01-30 13:15:45 -0500 | [diff] [blame] | 2152 | static void lock_mnt_tree(struct mount *mnt) |
| 2153 | { |
| 2154 | struct mount *p; |
| 2155 | |
| 2156 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 2157 | int flags = p->mnt.mnt_flags; |
| 2158 | /* Don't allow unprivileged users to change mount flags */ |
| 2159 | flags |= MNT_LOCK_ATIME; |
| 2160 | |
| 2161 | if (flags & MNT_READONLY) |
| 2162 | flags |= MNT_LOCK_READONLY; |
| 2163 | |
| 2164 | if (flags & MNT_NODEV) |
| 2165 | flags |= MNT_LOCK_NODEV; |
| 2166 | |
| 2167 | if (flags & MNT_NOSUID) |
| 2168 | flags |= MNT_LOCK_NOSUID; |
| 2169 | |
| 2170 | if (flags & MNT_NOEXEC) |
| 2171 | flags |= MNT_LOCK_NOEXEC; |
| 2172 | /* Don't allow unprivileged users to reveal what is under a mount */ |
| 2173 | if (list_empty(&p->mnt_expire)) |
| 2174 | flags |= MNT_LOCKED; |
| 2175 | p->mnt.mnt_flags = flags; |
| 2176 | } |
| 2177 | } |
| 2178 | |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 2179 | static void cleanup_group_ids(struct mount *mnt, struct mount *end) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2180 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2181 | struct mount *p; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2182 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2183 | for (p = mnt; p != end; p = next_mnt(p, mnt)) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2184 | if (p->mnt_group_id && !IS_MNT_SHARED(p)) |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 2185 | mnt_release_group_id(p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2186 | } |
| 2187 | } |
| 2188 | |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 2189 | static int invent_group_ids(struct mount *mnt, bool recurse) |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2190 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2191 | struct mount *p; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2192 | |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2193 | for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2194 | if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 2195 | int err = mnt_alloc_group_id(p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2196 | if (err) { |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 2197 | cleanup_group_ids(mnt, p); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2198 | return err; |
| 2199 | } |
| 2200 | } |
| 2201 | } |
| 2202 | |
| 2203 | return 0; |
| 2204 | } |
| 2205 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2206 | int count_mounts(struct mnt_namespace *ns, struct mount *mnt) |
| 2207 | { |
| 2208 | unsigned int max = READ_ONCE(sysctl_mount_max); |
Al Viro | 124f75f | 2022-02-13 22:42:30 -0500 | [diff] [blame] | 2209 | unsigned int mounts = 0; |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2210 | struct mount *p; |
| 2211 | |
Al Viro | 124f75f | 2022-02-13 22:42:30 -0500 | [diff] [blame] | 2212 | if (ns->mounts >= max) |
| 2213 | return -ENOSPC; |
| 2214 | max -= ns->mounts; |
| 2215 | if (ns->pending_mounts >= max) |
| 2216 | return -ENOSPC; |
| 2217 | max -= ns->pending_mounts; |
| 2218 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2219 | for (p = mnt; p; p = next_mnt(p, mnt)) |
| 2220 | mounts++; |
| 2221 | |
Al Viro | 124f75f | 2022-02-13 22:42:30 -0500 | [diff] [blame] | 2222 | if (mounts > max) |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2223 | return -ENOSPC; |
| 2224 | |
Al Viro | 124f75f | 2022-02-13 22:42:30 -0500 | [diff] [blame] | 2225 | ns->pending_mounts += mounts; |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2226 | return 0; |
| 2227 | } |
| 2228 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2229 | enum mnt_tree_flags_t { |
| 2230 | MNT_TREE_MOVE = BIT(0), |
| 2231 | MNT_TREE_BENEATH = BIT(1), |
| 2232 | }; |
| 2233 | |
| 2234 | /** |
| 2235 | * attach_recursive_mnt - attach a source mount tree |
| 2236 | * @source_mnt: mount tree to be attached |
| 2237 | * @top_mnt: mount that @source_mnt will be mounted on or mounted beneath |
| 2238 | * @dest_mp: the mountpoint @source_mnt will be mounted at |
| 2239 | * @flags: modify how @source_mnt is supposed to be attached |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2240 | * |
| 2241 | * NOTE: in the table below explains the semantics when a source mount |
| 2242 | * of a given type is attached to a destination mount of a given type. |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2243 | * --------------------------------------------------------------------------- |
| 2244 | * | BIND MOUNT OPERATION | |
| 2245 | * |************************************************************************** |
| 2246 | * | source-->| shared | private | slave | unbindable | |
| 2247 | * | dest | | | | | |
| 2248 | * | | | | | | | |
| 2249 | * | v | | | | | |
| 2250 | * |************************************************************************** |
| 2251 | * | shared | shared (++) | shared (+) | shared(+++)| invalid | |
| 2252 | * | | | | | | |
| 2253 | * |non-shared| shared (+) | private | slave (*) | invalid | |
| 2254 | * *************************************************************************** |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2255 | * A bind operation clones the source mount and mounts the clone on the |
| 2256 | * destination mount. |
| 2257 | * |
| 2258 | * (++) the cloned mount is propagated to all the mounts in the propagation |
| 2259 | * tree of the destination mount and the cloned mount is added to |
| 2260 | * the peer group of the source mount. |
| 2261 | * (+) the cloned mount is created under the destination mount and is marked |
| 2262 | * as shared. The cloned mount is added to the peer group of the source |
| 2263 | * mount. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 2264 | * (+++) the mount is propagated to all the mounts in the propagation tree |
| 2265 | * of the destination mount and the cloned mount is made slave |
| 2266 | * of the same master as that of the source mount. The cloned mount |
| 2267 | * is marked as 'shared and slave'. |
| 2268 | * (*) the cloned mount is made a slave of the same master as that of the |
| 2269 | * source mount. |
| 2270 | * |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2271 | * --------------------------------------------------------------------------- |
| 2272 | * | MOVE MOUNT OPERATION | |
| 2273 | * |************************************************************************** |
| 2274 | * | source-->| shared | private | slave | unbindable | |
| 2275 | * | dest | | | | | |
| 2276 | * | | | | | | | |
| 2277 | * | v | | | | | |
| 2278 | * |************************************************************************** |
| 2279 | * | shared | shared (+) | shared (+) | shared(+++) | invalid | |
| 2280 | * | | | | | | |
| 2281 | * |non-shared| shared (+*) | private | slave (*) | unbindable | |
| 2282 | * *************************************************************************** |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 2283 | * |
| 2284 | * (+) the mount is moved to the destination. And is then propagated to |
| 2285 | * all the mounts in the propagation tree of the destination mount. |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2286 | * (+*) the mount is moved to the destination. |
Ram Pai | 5afe002 | 2005-11-07 17:21:01 -0500 | [diff] [blame] | 2287 | * (+++) the mount is moved to the destination and is then propagated to |
| 2288 | * all the mounts belonging to the destination mount's propagation tree. |
| 2289 | * the mount is marked as 'shared and slave'. |
| 2290 | * (*) the mount continues to be a slave at the new location. |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2291 | * |
| 2292 | * if the source mount is a tree, the operations explained above is |
| 2293 | * applied to each mount in the tree. |
| 2294 | * Must be called without spinlocks held, since this function can sleep |
| 2295 | * in allocations. |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2296 | * |
| 2297 | * Context: The function expects namespace_lock() to be held. |
| 2298 | * Return: If @source_mnt was successfully attached 0 is returned. |
| 2299 | * Otherwise a negative error code is returned. |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2300 | */ |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 2301 | static int attach_recursive_mnt(struct mount *source_mnt, |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2302 | struct mount *top_mnt, |
| 2303 | struct mountpoint *dest_mp, |
| 2304 | enum mnt_tree_flags_t flags) |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2305 | { |
Al Viro | 3bd045c | 2019-01-30 13:15:45 -0500 | [diff] [blame] | 2306 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 2307 | HLIST_HEAD(tree_list); |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2308 | struct mnt_namespace *ns = top_mnt->mnt_ns; |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2309 | struct mountpoint *smp; |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2310 | struct mount *child, *dest_mnt, *p; |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 2311 | struct hlist_node *n; |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2312 | int err = 0; |
| 2313 | bool moving = flags & MNT_TREE_MOVE, beneath = flags & MNT_TREE_BENEATH; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2314 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2315 | /* |
| 2316 | * Preallocate a mountpoint in case the new mounts need to be |
| 2317 | * mounted beneath mounts on the same mountpoint. |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2318 | */ |
| 2319 | smp = get_mountpoint(source_mnt->mnt.mnt_root); |
| 2320 | if (IS_ERR(smp)) |
| 2321 | return PTR_ERR(smp); |
| 2322 | |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2323 | /* Is there space to add these mounts to the mount namespace? */ |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2324 | if (!moving) { |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2325 | err = count_mounts(ns, source_mnt); |
| 2326 | if (err) |
| 2327 | goto out; |
| 2328 | } |
| 2329 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2330 | if (beneath) |
| 2331 | dest_mnt = top_mnt->mnt_parent; |
| 2332 | else |
| 2333 | dest_mnt = top_mnt; |
| 2334 | |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2335 | if (IS_MNT_SHARED(dest_mnt)) { |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 2336 | err = invent_group_ids(source_mnt, true); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2337 | if (err) |
| 2338 | goto out; |
Al Viro | 0b1b901 | 2014-03-21 10:14:08 -0400 | [diff] [blame] | 2339 | err = propagate_mnt(dest_mnt, dest_mp, source_mnt, &tree_list); |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2340 | } |
| 2341 | lock_mount_hash(); |
| 2342 | if (err) |
| 2343 | goto out_cleanup_ids; |
| 2344 | |
| 2345 | if (IS_MNT_SHARED(dest_mnt)) { |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2346 | for (p = source_mnt; p; p = next_mnt(p, source_mnt)) |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 2347 | set_mnt_shared(p); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2348 | } |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2349 | |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2350 | if (moving) { |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2351 | if (beneath) |
| 2352 | dest_mp = smp; |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 2353 | unhash_mnt(source_mnt); |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2354 | attach_mnt(source_mnt, top_mnt, dest_mp, beneath); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2355 | touch_mnt_namespace(source_mnt->mnt_ns); |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2356 | } else { |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2357 | if (source_mnt->mnt_ns) { |
| 2358 | /* move from anon - the caller will destroy */ |
| 2359 | list_del_init(&source_mnt->mnt_ns->list); |
| 2360 | } |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2361 | if (beneath) |
| 2362 | mnt_set_mountpoint_beneath(source_mnt, top_mnt, smp); |
| 2363 | else |
| 2364 | mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2365 | commit_tree(source_mnt); |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 2366 | } |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2367 | |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 2368 | hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) { |
Al Viro | 1d6a32a | 2014-03-20 20:34:43 -0400 | [diff] [blame] | 2369 | struct mount *q; |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 2370 | hlist_del_init(&child->mnt_hash); |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2371 | q = __lookup_mnt(&child->mnt_parent->mnt, |
| 2372 | child->mnt_mountpoint); |
| 2373 | if (q) |
| 2374 | mnt_change_mountpoint(child, smp, q); |
Al Viro | 3bd045c | 2019-01-30 13:15:45 -0500 | [diff] [blame] | 2375 | /* Notice when we are propagating across user namespaces */ |
| 2376 | if (child->mnt_parent->mnt_ns->user_ns != user_ns) |
| 2377 | lock_mnt_tree(child); |
Christian Brauner | d728cf7 | 2019-06-17 23:22:14 +0200 | [diff] [blame] | 2378 | child->mnt.mnt_flags &= ~MNT_LOCKED; |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2379 | commit_tree(child); |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2380 | } |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2381 | put_mountpoint(smp); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2382 | unlock_mount_hash(); |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 2383 | |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2384 | return 0; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2385 | |
| 2386 | out_cleanup_ids: |
Al Viro | f2ebb3a | 2014-02-27 09:35:45 -0500 | [diff] [blame] | 2387 | while (!hlist_empty(&tree_list)) { |
| 2388 | child = hlist_entry(tree_list.first, struct mount, mnt_hash); |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2389 | child->mnt_parent->mnt_ns->pending_mounts = 0; |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 2390 | umount_tree(child, UMOUNT_SYNC); |
Al Viro | f2ebb3a | 2014-02-27 09:35:45 -0500 | [diff] [blame] | 2391 | } |
| 2392 | unlock_mount_hash(); |
Al Viro | 0b1b901 | 2014-03-21 10:14:08 -0400 | [diff] [blame] | 2393 | cleanup_group_ids(source_mnt, NULL); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2394 | out: |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 2395 | ns->pending_mounts = 0; |
Eric W. Biederman | 1064f87 | 2017-01-20 18:28:35 +1300 | [diff] [blame] | 2396 | |
| 2397 | read_seqlock_excl(&mount_lock); |
| 2398 | put_mountpoint(smp); |
| 2399 | read_sequnlock_excl(&mount_lock); |
| 2400 | |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2401 | return err; |
Ram Pai | b90fa9a | 2005-11-07 17:19:50 -0500 | [diff] [blame] | 2402 | } |
| 2403 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2404 | /** |
| 2405 | * do_lock_mount - lock mount and mountpoint |
| 2406 | * @path: target path |
| 2407 | * @beneath: whether the intention is to mount beneath @path |
| 2408 | * |
| 2409 | * Follow the mount stack on @path until the top mount @mnt is found. If |
| 2410 | * the initial @path->{mnt,dentry} is a mountpoint lookup the first |
| 2411 | * mount stacked on top of it. Then simply follow @{mnt,mnt->mnt_root} |
| 2412 | * until nothing is stacked on top of it anymore. |
| 2413 | * |
| 2414 | * Acquire the inode_lock() on the top mount's ->mnt_root to protect |
| 2415 | * against concurrent removal of the new mountpoint from another mount |
| 2416 | * namespace. |
| 2417 | * |
| 2418 | * If @beneath is requested, acquire inode_lock() on @mnt's mountpoint |
| 2419 | * @mp on @mnt->mnt_parent must be acquired. This protects against a |
| 2420 | * concurrent unlink of @mp->mnt_dentry from another mount namespace |
| 2421 | * where @mnt doesn't have a child mount mounted @mp. A concurrent |
| 2422 | * removal of @mnt->mnt_root doesn't matter as nothing will be mounted |
| 2423 | * on top of it for @beneath. |
| 2424 | * |
| 2425 | * In addition, @beneath needs to make sure that @mnt hasn't been |
| 2426 | * unmounted or moved from its current mountpoint in between dropping |
| 2427 | * @mount_lock and acquiring @namespace_sem. For the !@beneath case @mnt |
| 2428 | * being unmounted would be detected later by e.g., calling |
| 2429 | * check_mnt(mnt) in the function it's called from. For the @beneath |
| 2430 | * case however, it's useful to detect it directly in do_lock_mount(). |
| 2431 | * If @mnt hasn't been unmounted then @mnt->mnt_mountpoint still points |
| 2432 | * to @mnt->mnt_mp->m_dentry. But if @mnt has been unmounted it will |
| 2433 | * point to @mnt->mnt_root and @mnt->mnt_mp will be NULL. |
| 2434 | * |
| 2435 | * Return: Either the target mountpoint on the top mount or the top |
| 2436 | * mount's mountpoint. |
| 2437 | */ |
| 2438 | static struct mountpoint *do_lock_mount(struct path *path, bool beneath) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2439 | { |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2440 | struct vfsmount *mnt = path->mnt; |
Christian Brauner | 64f44b2 | 2023-05-03 13:18:41 +0200 | [diff] [blame] | 2441 | struct dentry *dentry; |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2442 | struct mountpoint *mp = ERR_PTR(-ENOENT); |
Christian Brauner | 64f44b2 | 2023-05-03 13:18:41 +0200 | [diff] [blame] | 2443 | |
| 2444 | for (;;) { |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2445 | struct mount *m; |
| 2446 | |
| 2447 | if (beneath) { |
| 2448 | m = real_mount(mnt); |
| 2449 | read_seqlock_excl(&mount_lock); |
| 2450 | dentry = dget(m->mnt_mountpoint); |
| 2451 | read_sequnlock_excl(&mount_lock); |
| 2452 | } else { |
| 2453 | dentry = path->dentry; |
| 2454 | } |
| 2455 | |
Christian Brauner | 64f44b2 | 2023-05-03 13:18:41 +0200 | [diff] [blame] | 2456 | inode_lock(dentry->d_inode); |
| 2457 | if (unlikely(cant_mount(dentry))) { |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2458 | inode_unlock(dentry->d_inode); |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2459 | goto out; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2460 | } |
Christian Brauner | 64f44b2 | 2023-05-03 13:18:41 +0200 | [diff] [blame] | 2461 | |
| 2462 | namespace_lock(); |
| 2463 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2464 | if (beneath && (!is_mounted(mnt) || m->mnt_mountpoint != dentry)) { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2465 | namespace_unlock(); |
| 2466 | inode_unlock(dentry->d_inode); |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2467 | goto out; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2468 | } |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2469 | |
Christian Brauner | 64f44b2 | 2023-05-03 13:18:41 +0200 | [diff] [blame] | 2470 | mnt = lookup_mnt(path); |
| 2471 | if (likely(!mnt)) |
| 2472 | break; |
| 2473 | |
| 2474 | namespace_unlock(); |
| 2475 | inode_unlock(dentry->d_inode); |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2476 | if (beneath) |
| 2477 | dput(dentry); |
Christian Brauner | 64f44b2 | 2023-05-03 13:18:41 +0200 | [diff] [blame] | 2478 | path_put(path); |
| 2479 | path->mnt = mnt; |
| 2480 | path->dentry = dget(mnt->mnt_root); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2481 | } |
Christian Brauner | 64f44b2 | 2023-05-03 13:18:41 +0200 | [diff] [blame] | 2482 | |
| 2483 | mp = get_mountpoint(dentry); |
| 2484 | if (IS_ERR(mp)) { |
| 2485 | namespace_unlock(); |
| 2486 | inode_unlock(dentry->d_inode); |
| 2487 | } |
| 2488 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2489 | out: |
| 2490 | if (beneath) |
| 2491 | dput(dentry); |
| 2492 | |
Christian Brauner | 64f44b2 | 2023-05-03 13:18:41 +0200 | [diff] [blame] | 2493 | return mp; |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2494 | } |
| 2495 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2496 | static inline struct mountpoint *lock_mount(struct path *path) |
| 2497 | { |
| 2498 | return do_lock_mount(path, false); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2499 | } |
| 2500 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2501 | static void unlock_mount(struct mountpoint *where) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2502 | { |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2503 | struct dentry *dentry = where->m_dentry; |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 2504 | |
| 2505 | read_seqlock_excl(&mount_lock); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2506 | put_mountpoint(where); |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 2507 | read_sequnlock_excl(&mount_lock); |
| 2508 | |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 2509 | namespace_unlock(); |
Al Viro | 5955102 | 2016-01-22 15:40:57 -0500 | [diff] [blame] | 2510 | inode_unlock(dentry->d_inode); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2511 | } |
| 2512 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2513 | static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2514 | { |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2515 | if (mnt->mnt.mnt_sb->s_flags & SB_NOUSER) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2516 | return -EINVAL; |
| 2517 | |
David Howells | e36cb0b | 2015-01-29 12:02:35 +0000 | [diff] [blame] | 2518 | if (d_is_dir(mp->m_dentry) != |
| 2519 | d_is_dir(mnt->mnt.mnt_root)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2520 | return -ENOTDIR; |
| 2521 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 2522 | return attach_recursive_mnt(mnt, p, mp, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2523 | } |
| 2524 | |
| 2525 | /* |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2526 | * Sanity check the flags to change_mnt_propagation. |
| 2527 | */ |
| 2528 | |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2529 | static int flags_to_propagation_type(int ms_flags) |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2530 | { |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2531 | int type = ms_flags & ~(MS_REC | MS_SILENT); |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2532 | |
| 2533 | /* Fail if any non-propagation flags are set */ |
| 2534 | if (type & ~(MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
| 2535 | return 0; |
| 2536 | /* Only one propagation flag should be set */ |
| 2537 | if (!is_power_of_2(type)) |
| 2538 | return 0; |
| 2539 | return type; |
| 2540 | } |
| 2541 | |
| 2542 | /* |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2543 | * recursively change the type of the mountpoint. |
| 2544 | */ |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2545 | static int do_change_type(struct path *path, int ms_flags) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2546 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2547 | struct mount *m; |
Al Viro | 4b8b21f | 2011-11-24 19:54:23 -0500 | [diff] [blame] | 2548 | struct mount *mnt = real_mount(path->mnt); |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2549 | int recurse = ms_flags & MS_REC; |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2550 | int type; |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2551 | int err = 0; |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2552 | |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 2553 | if (!path_mounted(path)) |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2554 | return -EINVAL; |
| 2555 | |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2556 | type = flags_to_propagation_type(ms_flags); |
Valerie Aurora | 7a2e8a8 | 2010-08-26 11:07:22 -0700 | [diff] [blame] | 2557 | if (!type) |
| 2558 | return -EINVAL; |
| 2559 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2560 | namespace_lock(); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2561 | if (type == MS_SHARED) { |
| 2562 | err = invent_group_ids(mnt, recurse); |
| 2563 | if (err) |
| 2564 | goto out_unlock; |
| 2565 | } |
| 2566 | |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2567 | lock_mount_hash(); |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2568 | for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) |
Al Viro | 0f0afb1 | 2011-11-24 20:43:10 -0500 | [diff] [blame] | 2569 | change_mnt_propagation(m, type); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2570 | unlock_mount_hash(); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2571 | |
| 2572 | out_unlock: |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 2573 | namespace_unlock(); |
Miklos Szeredi | 719f5d7 | 2008-03-27 13:06:23 +0100 | [diff] [blame] | 2574 | return err; |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2575 | } |
| 2576 | |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2577 | static struct mount *__do_loopback(struct path *old_path, int recurse) |
| 2578 | { |
| 2579 | struct mount *mnt = ERR_PTR(-EINVAL), *old = real_mount(old_path->mnt); |
| 2580 | |
| 2581 | if (IS_MNT_UNBINDABLE(old)) |
| 2582 | return mnt; |
| 2583 | |
| 2584 | if (!check_mnt(old) && old_path->dentry->d_op != &ns_dentry_operations) |
| 2585 | return mnt; |
| 2586 | |
| 2587 | if (!recurse && has_locked_children(old, old_path->dentry)) |
| 2588 | return mnt; |
| 2589 | |
| 2590 | if (recurse) |
| 2591 | mnt = copy_tree(old, old_path->dentry, CL_COPY_MNT_NS_FILE); |
| 2592 | else |
| 2593 | mnt = clone_mnt(old, old_path->dentry, 0); |
| 2594 | |
| 2595 | if (!IS_ERR(mnt)) |
| 2596 | mnt->mnt.mnt_flags &= ~MNT_LOCKED; |
| 2597 | |
| 2598 | return mnt; |
| 2599 | } |
| 2600 | |
Ram Pai | 07b2088 | 2005-11-07 17:19:07 -0500 | [diff] [blame] | 2601 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2602 | * do loopback mount. |
| 2603 | */ |
Al Viro | 808d4e3 | 2012-10-11 11:42:01 -0400 | [diff] [blame] | 2604 | static int do_loopback(struct path *path, const char *old_name, |
Eric Sandeen | 2dafe1c | 2008-02-08 04:22:12 -0800 | [diff] [blame] | 2605 | int recurse) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2606 | { |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2607 | struct path old_path; |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2608 | struct mount *mnt = NULL, *parent; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2609 | struct mountpoint *mp; |
Al Viro | 57eccb8 | 2013-02-22 22:49:10 -0500 | [diff] [blame] | 2610 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2611 | if (!old_name || !*old_name) |
| 2612 | return -EINVAL; |
Trond Myklebust | 815d405 | 2011-09-26 20:36:09 -0400 | [diff] [blame] | 2613 | err = kern_path(old_name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2614 | if (err) |
| 2615 | return err; |
| 2616 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 2617 | err = -EINVAL; |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 2618 | if (mnt_ns_loop(old_path.dentry)) |
David Howells | dd111b3 | 2017-07-04 17:25:09 +0100 | [diff] [blame] | 2619 | goto out; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 2620 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2621 | mp = lock_mount(path); |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2622 | if (IS_ERR(mp)) { |
| 2623 | err = PTR_ERR(mp); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 2624 | goto out; |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2625 | } |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2626 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2627 | parent = real_mount(path->mnt); |
Al Viro | e149ed2 | 2014-11-01 10:57:28 -0400 | [diff] [blame] | 2628 | if (!check_mnt(parent)) |
| 2629 | goto out2; |
| 2630 | |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2631 | mnt = __do_loopback(&old_path, recurse); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2632 | if (IS_ERR(mnt)) { |
| 2633 | err = PTR_ERR(mnt); |
Andrey Vagin | e9c5d8a | 2013-04-09 17:33:29 +0400 | [diff] [blame] | 2634 | goto out2; |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 2635 | } |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2636 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2637 | err = graft_tree(mnt, parent, mp); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2638 | if (err) { |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2639 | lock_mount_hash(); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 2640 | umount_tree(mnt, UMOUNT_SYNC); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 2641 | unlock_mount_hash(); |
Ram Pai | 5b83d2c5c | 2005-11-07 17:16:29 -0500 | [diff] [blame] | 2642 | } |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 2643 | out2: |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 2644 | unlock_mount(mp); |
Al Viro | ccd48bc | 2005-11-07 17:15:04 -0500 | [diff] [blame] | 2645 | out: |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2646 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2647 | return err; |
| 2648 | } |
| 2649 | |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2650 | static struct file *open_detached_copy(struct path *path, bool recursive) |
| 2651 | { |
| 2652 | struct user_namespace *user_ns = current->nsproxy->mnt_ns->user_ns; |
| 2653 | struct mnt_namespace *ns = alloc_mnt_ns(user_ns, true); |
| 2654 | struct mount *mnt, *p; |
| 2655 | struct file *file; |
| 2656 | |
| 2657 | if (IS_ERR(ns)) |
| 2658 | return ERR_CAST(ns); |
| 2659 | |
| 2660 | namespace_lock(); |
| 2661 | mnt = __do_loopback(path, recursive); |
| 2662 | if (IS_ERR(mnt)) { |
| 2663 | namespace_unlock(); |
| 2664 | free_mnt_ns(ns); |
| 2665 | return ERR_CAST(mnt); |
| 2666 | } |
| 2667 | |
| 2668 | lock_mount_hash(); |
| 2669 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
| 2670 | p->mnt_ns = ns; |
| 2671 | ns->mounts++; |
| 2672 | } |
| 2673 | ns->root = mnt; |
| 2674 | list_add_tail(&ns->list, &mnt->mnt_list); |
| 2675 | mntget(&mnt->mnt); |
| 2676 | unlock_mount_hash(); |
| 2677 | namespace_unlock(); |
| 2678 | |
| 2679 | mntput(path->mnt); |
| 2680 | path->mnt = &mnt->mnt; |
| 2681 | file = dentry_open(path, O_PATH, current_cred()); |
| 2682 | if (IS_ERR(file)) |
| 2683 | dissolve_on_fput(path->mnt); |
| 2684 | else |
| 2685 | file->f_mode |= FMODE_NEED_UNMOUNT; |
| 2686 | return file; |
| 2687 | } |
| 2688 | |
Ben Dooks | 2658ce0 | 2019-10-15 11:35:02 +0100 | [diff] [blame] | 2689 | SYSCALL_DEFINE3(open_tree, int, dfd, const char __user *, filename, unsigned, flags) |
Al Viro | a07b200 | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 2690 | { |
| 2691 | struct file *file; |
| 2692 | struct path path; |
| 2693 | int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW; |
| 2694 | bool detached = flags & OPEN_TREE_CLONE; |
| 2695 | int error; |
| 2696 | int fd; |
| 2697 | |
| 2698 | BUILD_BUG_ON(OPEN_TREE_CLOEXEC != O_CLOEXEC); |
| 2699 | |
| 2700 | if (flags & ~(AT_EMPTY_PATH | AT_NO_AUTOMOUNT | AT_RECURSIVE | |
| 2701 | AT_SYMLINK_NOFOLLOW | OPEN_TREE_CLONE | |
| 2702 | OPEN_TREE_CLOEXEC)) |
| 2703 | return -EINVAL; |
| 2704 | |
| 2705 | if ((flags & (AT_RECURSIVE | OPEN_TREE_CLONE)) == AT_RECURSIVE) |
| 2706 | return -EINVAL; |
| 2707 | |
| 2708 | if (flags & AT_NO_AUTOMOUNT) |
| 2709 | lookup_flags &= ~LOOKUP_AUTOMOUNT; |
| 2710 | if (flags & AT_SYMLINK_NOFOLLOW) |
| 2711 | lookup_flags &= ~LOOKUP_FOLLOW; |
| 2712 | if (flags & AT_EMPTY_PATH) |
| 2713 | lookup_flags |= LOOKUP_EMPTY; |
| 2714 | |
| 2715 | if (detached && !may_mount()) |
| 2716 | return -EPERM; |
| 2717 | |
| 2718 | fd = get_unused_fd_flags(flags & O_CLOEXEC); |
| 2719 | if (fd < 0) |
| 2720 | return fd; |
| 2721 | |
| 2722 | error = user_path_at(dfd, filename, lookup_flags, &path); |
| 2723 | if (unlikely(error)) { |
| 2724 | file = ERR_PTR(error); |
| 2725 | } else { |
| 2726 | if (detached) |
| 2727 | file = open_detached_copy(&path, flags & AT_RECURSIVE); |
| 2728 | else |
| 2729 | file = dentry_open(&path, O_PATH, current_cred()); |
| 2730 | path_put(&path); |
| 2731 | } |
| 2732 | if (IS_ERR(file)) { |
| 2733 | put_unused_fd(fd); |
| 2734 | return PTR_ERR(file); |
| 2735 | } |
| 2736 | fd_install(fd, file); |
| 2737 | return fd; |
| 2738 | } |
| 2739 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2740 | /* |
| 2741 | * Don't allow locked mount flags to be cleared. |
| 2742 | * |
| 2743 | * No locks need to be held here while testing the various MNT_LOCK |
| 2744 | * flags because those flags can never be cleared once they are set. |
| 2745 | */ |
| 2746 | static bool can_change_locked_flags(struct mount *mnt, unsigned int mnt_flags) |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2747 | { |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2748 | unsigned int fl = mnt->mnt.mnt_flags; |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2749 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2750 | if ((fl & MNT_LOCK_READONLY) && |
| 2751 | !(mnt_flags & MNT_READONLY)) |
| 2752 | return false; |
| 2753 | |
| 2754 | if ((fl & MNT_LOCK_NODEV) && |
| 2755 | !(mnt_flags & MNT_NODEV)) |
| 2756 | return false; |
| 2757 | |
| 2758 | if ((fl & MNT_LOCK_NOSUID) && |
| 2759 | !(mnt_flags & MNT_NOSUID)) |
| 2760 | return false; |
| 2761 | |
| 2762 | if ((fl & MNT_LOCK_NOEXEC) && |
| 2763 | !(mnt_flags & MNT_NOEXEC)) |
| 2764 | return false; |
| 2765 | |
| 2766 | if ((fl & MNT_LOCK_ATIME) && |
| 2767 | ((fl & MNT_ATIME_MASK) != (mnt_flags & MNT_ATIME_MASK))) |
| 2768 | return false; |
| 2769 | |
| 2770 | return true; |
| 2771 | } |
| 2772 | |
| 2773 | static int change_mount_ro_state(struct mount *mnt, unsigned int mnt_flags) |
| 2774 | { |
| 2775 | bool readonly_request = (mnt_flags & MNT_READONLY); |
| 2776 | |
| 2777 | if (readonly_request == __mnt_is_readonly(&mnt->mnt)) |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2778 | return 0; |
| 2779 | |
| 2780 | if (readonly_request) |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2781 | return mnt_make_readonly(mnt); |
| 2782 | |
Christian Brauner | 68847c9 | 2021-01-21 14:19:48 +0100 | [diff] [blame] | 2783 | mnt->mnt.mnt_flags &= ~MNT_READONLY; |
| 2784 | return 0; |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2785 | } |
| 2786 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2787 | static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags) |
| 2788 | { |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2789 | mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; |
| 2790 | mnt->mnt.mnt_flags = mnt_flags; |
| 2791 | touch_mnt_namespace(mnt->mnt_ns); |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2792 | } |
| 2793 | |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2794 | static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *mnt) |
| 2795 | { |
| 2796 | struct super_block *sb = mnt->mnt_sb; |
| 2797 | |
| 2798 | if (!__mnt_is_readonly(mnt) && |
Anthony Iliopoulos | a128b05 | 2022-03-22 14:39:22 -0700 | [diff] [blame] | 2799 | (!(sb->s_iflags & SB_I_TS_EXPIRY_WARNED)) && |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2800 | (ktime_get_real_seconds() + TIME_UPTIME_SEC_MAX > sb->s_time_max)) { |
| 2801 | char *buf = (char *)__get_free_page(GFP_KERNEL); |
| 2802 | char *mntpath = buf ? d_path(mountpoint, buf, PAGE_SIZE) : ERR_PTR(-ENOMEM); |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2803 | |
Andy Shevchenko | 74e60b8 | 2023-03-14 17:09:06 +0200 | [diff] [blame] | 2804 | pr_warn("%s filesystem being %s at %s supports timestamps until %ptTd (0x%llx)\n", |
Eric Biggers | 0ecee66 | 2019-10-16 19:48:14 -0700 | [diff] [blame] | 2805 | sb->s_type->name, |
| 2806 | is_mounted(mnt) ? "remounted" : "mounted", |
Andy Shevchenko | 74e60b8 | 2023-03-14 17:09:06 +0200 | [diff] [blame] | 2807 | mntpath, &sb->s_time_max, |
| 2808 | (unsigned long long)sb->s_time_max); |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2809 | |
| 2810 | free_page((unsigned long)buf); |
Anthony Iliopoulos | a128b05 | 2022-03-22 14:39:22 -0700 | [diff] [blame] | 2811 | sb->s_iflags |= SB_I_TS_EXPIRY_WARNED; |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2812 | } |
| 2813 | } |
| 2814 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2815 | /* |
| 2816 | * Handle reconfiguration of the mountpoint only without alteration of the |
| 2817 | * superblock it refers to. This is triggered by specifying MS_REMOUNT|MS_BIND |
| 2818 | * to mount(2). |
| 2819 | */ |
| 2820 | static int do_reconfigure_mnt(struct path *path, unsigned int mnt_flags) |
| 2821 | { |
| 2822 | struct super_block *sb = path->mnt->mnt_sb; |
| 2823 | struct mount *mnt = real_mount(path->mnt); |
| 2824 | int ret; |
| 2825 | |
| 2826 | if (!check_mnt(mnt)) |
| 2827 | return -EINVAL; |
| 2828 | |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 2829 | if (!path_mounted(path)) |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2830 | return -EINVAL; |
| 2831 | |
| 2832 | if (!can_change_locked_flags(mnt, mnt_flags)) |
| 2833 | return -EPERM; |
| 2834 | |
Christian Brauner | e58ace1 | 2021-01-21 14:19:50 +0100 | [diff] [blame] | 2835 | /* |
| 2836 | * We're only checking whether the superblock is read-only not |
| 2837 | * changing it, so only take down_read(&sb->s_umount). |
| 2838 | */ |
| 2839 | down_read(&sb->s_umount); |
Christian Brauner | 68847c9 | 2021-01-21 14:19:48 +0100 | [diff] [blame] | 2840 | lock_mount_hash(); |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2841 | ret = change_mount_ro_state(mnt, mnt_flags); |
| 2842 | if (ret == 0) |
| 2843 | set_mount_attributes(mnt, mnt_flags); |
Christian Brauner | 68847c9 | 2021-01-21 14:19:48 +0100 | [diff] [blame] | 2844 | unlock_mount_hash(); |
Christian Brauner | e58ace1 | 2021-01-21 14:19:50 +0100 | [diff] [blame] | 2845 | up_read(&sb->s_umount); |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2846 | |
| 2847 | mnt_warn_timestamp_expiry(path, &mnt->mnt); |
| 2848 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2849 | return ret; |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 2850 | } |
| 2851 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2852 | /* |
| 2853 | * change filesystem flags. dir should be a physical root of filesystem. |
| 2854 | * If you've mounted a non-root directory somewhere and want to do remount |
| 2855 | * on it - tough luck. |
| 2856 | */ |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 2857 | static int do_remount(struct path *path, int ms_flags, int sb_flags, |
| 2858 | int mnt_flags, void *data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2859 | { |
| 2860 | int err; |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 2861 | struct super_block *sb = path->mnt->mnt_sb; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2862 | struct mount *mnt = real_mount(path->mnt); |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 2863 | struct fs_context *fc; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2864 | |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 2865 | if (!check_mnt(mnt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2866 | return -EINVAL; |
| 2867 | |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 2868 | if (!path_mounted(path)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2869 | return -EINVAL; |
| 2870 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 2871 | if (!can_change_locked_flags(mnt, mnt_flags)) |
Eric W. Biederman | 07b6455 | 2014-07-28 17:10:56 -0700 | [diff] [blame] | 2872 | return -EPERM; |
Eric W. Biederman | 9566d67 | 2014-07-28 17:26:07 -0700 | [diff] [blame] | 2873 | |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 2874 | fc = fs_context_for_reconfigure(path->dentry, sb_flags, MS_RMT_MASK); |
| 2875 | if (IS_ERR(fc)) |
| 2876 | return PTR_ERR(fc); |
Eric Paris | ff36fe2 | 2011-03-03 16:09:14 -0500 | [diff] [blame] | 2877 | |
Miklos Szeredi | b330966 | 2020-07-14 14:45:41 +0200 | [diff] [blame] | 2878 | fc->oldapi = true; |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 2879 | err = parse_monolithic_mount_data(fc, data); |
| 2880 | if (!err) { |
| 2881 | down_write(&sb->s_umount); |
| 2882 | err = -EPERM; |
| 2883 | if (ns_capable(sb->s_user_ns, CAP_SYS_ADMIN)) { |
| 2884 | err = reconfigure_super(fc); |
Christian Brauner | 68847c9 | 2021-01-21 14:19:48 +0100 | [diff] [blame] | 2885 | if (!err) { |
| 2886 | lock_mount_hash(); |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 2887 | set_mount_attributes(mnt, mnt_flags); |
Christian Brauner | 68847c9 | 2021-01-21 14:19:48 +0100 | [diff] [blame] | 2888 | unlock_mount_hash(); |
| 2889 | } |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 2890 | } |
| 2891 | up_write(&sb->s_umount); |
Dan Williams | 0e55a7c | 2008-09-26 19:01:20 -0700 | [diff] [blame] | 2892 | } |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 2893 | |
| 2894 | mnt_warn_timestamp_expiry(path, &mnt->mnt); |
| 2895 | |
David Howells | 8d0347f | 2018-11-04 09:28:36 -0500 | [diff] [blame] | 2896 | put_fs_context(fc); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2897 | return err; |
| 2898 | } |
| 2899 | |
Al Viro | cbbe362 | 2011-11-24 20:01:19 -0500 | [diff] [blame] | 2900 | static inline int tree_contains_unbindable(struct mount *mnt) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2901 | { |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 2902 | struct mount *p; |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 2903 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 2904 | if (IS_MNT_UNBINDABLE(p)) |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 2905 | return 1; |
| 2906 | } |
| 2907 | return 0; |
| 2908 | } |
| 2909 | |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 2910 | /* |
| 2911 | * Check that there aren't references to earlier/same mount namespaces in the |
| 2912 | * specified subtree. Such references can act as pins for mount namespaces |
| 2913 | * that aren't checked by the mount-cycle checking code, thereby allowing |
| 2914 | * cycles to be made. |
| 2915 | */ |
| 2916 | static bool check_for_nsfs_mounts(struct mount *subtree) |
| 2917 | { |
| 2918 | struct mount *p; |
| 2919 | bool ret = false; |
| 2920 | |
| 2921 | lock_mount_hash(); |
| 2922 | for (p = subtree; p; p = next_mnt(p, subtree)) |
| 2923 | if (mnt_ns_loop(p->mnt.mnt_root)) |
| 2924 | goto out; |
| 2925 | |
| 2926 | ret = true; |
| 2927 | out: |
| 2928 | unlock_mount_hash(); |
| 2929 | return ret; |
| 2930 | } |
| 2931 | |
Pavel Tikhomirov | 9ffb14e | 2021-07-15 13:07:13 +0300 | [diff] [blame] | 2932 | static int do_set_group(struct path *from_path, struct path *to_path) |
| 2933 | { |
| 2934 | struct mount *from, *to; |
| 2935 | int err; |
| 2936 | |
| 2937 | from = real_mount(from_path->mnt); |
| 2938 | to = real_mount(to_path->mnt); |
| 2939 | |
| 2940 | namespace_lock(); |
| 2941 | |
| 2942 | err = -EINVAL; |
| 2943 | /* To and From must be mounted */ |
| 2944 | if (!is_mounted(&from->mnt)) |
| 2945 | goto out; |
| 2946 | if (!is_mounted(&to->mnt)) |
| 2947 | goto out; |
| 2948 | |
| 2949 | err = -EPERM; |
| 2950 | /* We should be allowed to modify mount namespaces of both mounts */ |
| 2951 | if (!ns_capable(from->mnt_ns->user_ns, CAP_SYS_ADMIN)) |
| 2952 | goto out; |
| 2953 | if (!ns_capable(to->mnt_ns->user_ns, CAP_SYS_ADMIN)) |
| 2954 | goto out; |
| 2955 | |
| 2956 | err = -EINVAL; |
| 2957 | /* To and From paths should be mount roots */ |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 2958 | if (!path_mounted(from_path)) |
Pavel Tikhomirov | 9ffb14e | 2021-07-15 13:07:13 +0300 | [diff] [blame] | 2959 | goto out; |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 2960 | if (!path_mounted(to_path)) |
Pavel Tikhomirov | 9ffb14e | 2021-07-15 13:07:13 +0300 | [diff] [blame] | 2961 | goto out; |
| 2962 | |
| 2963 | /* Setting sharing groups is only allowed across same superblock */ |
| 2964 | if (from->mnt.mnt_sb != to->mnt.mnt_sb) |
| 2965 | goto out; |
| 2966 | |
| 2967 | /* From mount root should be wider than To mount root */ |
| 2968 | if (!is_subdir(to->mnt.mnt_root, from->mnt.mnt_root)) |
| 2969 | goto out; |
| 2970 | |
| 2971 | /* From mount should not have locked children in place of To's root */ |
| 2972 | if (has_locked_children(from, to->mnt.mnt_root)) |
| 2973 | goto out; |
| 2974 | |
| 2975 | /* Setting sharing groups is only allowed on private mounts */ |
| 2976 | if (IS_MNT_SHARED(to) || IS_MNT_SLAVE(to)) |
| 2977 | goto out; |
| 2978 | |
| 2979 | /* From should not be private */ |
| 2980 | if (!IS_MNT_SHARED(from) && !IS_MNT_SLAVE(from)) |
| 2981 | goto out; |
| 2982 | |
| 2983 | if (IS_MNT_SLAVE(from)) { |
| 2984 | struct mount *m = from->mnt_master; |
| 2985 | |
| 2986 | list_add(&to->mnt_slave, &m->mnt_slave_list); |
| 2987 | to->mnt_master = m; |
| 2988 | } |
| 2989 | |
| 2990 | if (IS_MNT_SHARED(from)) { |
| 2991 | to->mnt_group_id = from->mnt_group_id; |
| 2992 | list_add(&to->mnt_share, &from->mnt_share); |
| 2993 | lock_mount_hash(); |
| 2994 | set_mnt_shared(to); |
| 2995 | unlock_mount_hash(); |
| 2996 | } |
| 2997 | |
| 2998 | err = 0; |
| 2999 | out: |
| 3000 | namespace_unlock(); |
| 3001 | return err; |
| 3002 | } |
| 3003 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 3004 | /** |
| 3005 | * path_overmounted - check if path is overmounted |
| 3006 | * @path: path to check |
| 3007 | * |
| 3008 | * Check if path is overmounted, i.e., if there's a mount on top of |
| 3009 | * @path->mnt with @path->dentry as mountpoint. |
| 3010 | * |
| 3011 | * Context: This function expects namespace_lock() to be held. |
| 3012 | * Return: If path is overmounted true is returned, false if not. |
| 3013 | */ |
| 3014 | static inline bool path_overmounted(const struct path *path) |
| 3015 | { |
| 3016 | rcu_read_lock(); |
| 3017 | if (unlikely(__lookup_mnt(path->mnt, path->dentry))) { |
| 3018 | rcu_read_unlock(); |
| 3019 | return true; |
| 3020 | } |
| 3021 | rcu_read_unlock(); |
| 3022 | return false; |
| 3023 | } |
| 3024 | |
| 3025 | /** |
| 3026 | * can_move_mount_beneath - check that we can mount beneath the top mount |
| 3027 | * @from: mount to mount beneath |
| 3028 | * @to: mount under which to mount |
| 3029 | * |
| 3030 | * - Make sure that @to->dentry is actually the root of a mount under |
| 3031 | * which we can mount another mount. |
| 3032 | * - Make sure that nothing can be mounted beneath the caller's current |
| 3033 | * root or the rootfs of the namespace. |
| 3034 | * - Make sure that the caller can unmount the topmost mount ensuring |
| 3035 | * that the caller could reveal the underlying mountpoint. |
| 3036 | * - Ensure that nothing has been mounted on top of @from before we |
| 3037 | * grabbed @namespace_sem to avoid creating pointless shadow mounts. |
| 3038 | * - Prevent mounting beneath a mount if the propagation relationship |
| 3039 | * between the source mount, parent mount, and top mount would lead to |
| 3040 | * nonsensical mount trees. |
| 3041 | * |
| 3042 | * Context: This function expects namespace_lock() to be held. |
| 3043 | * Return: On success 0, and on error a negative error code is returned. |
| 3044 | */ |
| 3045 | static int can_move_mount_beneath(const struct path *from, |
| 3046 | const struct path *to, |
| 3047 | const struct mountpoint *mp) |
| 3048 | { |
| 3049 | struct mount *mnt_from = real_mount(from->mnt), |
| 3050 | *mnt_to = real_mount(to->mnt), |
| 3051 | *parent_mnt_to = mnt_to->mnt_parent; |
| 3052 | |
| 3053 | if (!mnt_has_parent(mnt_to)) |
| 3054 | return -EINVAL; |
| 3055 | |
| 3056 | if (!path_mounted(to)) |
| 3057 | return -EINVAL; |
| 3058 | |
| 3059 | if (IS_MNT_LOCKED(mnt_to)) |
| 3060 | return -EINVAL; |
| 3061 | |
| 3062 | /* Avoid creating shadow mounts during mount propagation. */ |
| 3063 | if (path_overmounted(from)) |
| 3064 | return -EINVAL; |
| 3065 | |
| 3066 | /* |
| 3067 | * Mounting beneath the rootfs only makes sense when the |
| 3068 | * semantics of pivot_root(".", ".") are used. |
| 3069 | */ |
| 3070 | if (&mnt_to->mnt == current->fs->root.mnt) |
| 3071 | return -EINVAL; |
| 3072 | if (parent_mnt_to == current->nsproxy->mnt_ns->root) |
| 3073 | return -EINVAL; |
| 3074 | |
| 3075 | for (struct mount *p = mnt_from; mnt_has_parent(p); p = p->mnt_parent) |
| 3076 | if (p == mnt_to) |
| 3077 | return -EINVAL; |
| 3078 | |
| 3079 | /* |
| 3080 | * If the parent mount propagates to the child mount this would |
| 3081 | * mean mounting @mnt_from on @mnt_to->mnt_parent and then |
| 3082 | * propagating a copy @c of @mnt_from on top of @mnt_to. This |
| 3083 | * defeats the whole purpose of mounting beneath another mount. |
| 3084 | */ |
| 3085 | if (propagation_would_overmount(parent_mnt_to, mnt_to, mp)) |
| 3086 | return -EINVAL; |
| 3087 | |
| 3088 | /* |
| 3089 | * If @mnt_to->mnt_parent propagates to @mnt_from this would |
| 3090 | * mean propagating a copy @c of @mnt_from on top of @mnt_from. |
| 3091 | * Afterwards @mnt_from would be mounted on top of |
| 3092 | * @mnt_to->mnt_parent and @mnt_to would be unmounted from |
| 3093 | * @mnt->mnt_parent and remounted on @mnt_from. But since @c is |
| 3094 | * already mounted on @mnt_from, @mnt_to would ultimately be |
| 3095 | * remounted on top of @c. Afterwards, @mnt_from would be |
| 3096 | * covered by a copy @c of @mnt_from and @c would be covered by |
| 3097 | * @mnt_from itself. This defeats the whole purpose of mounting |
| 3098 | * @mnt_from beneath @mnt_to. |
| 3099 | */ |
| 3100 | if (propagation_would_overmount(parent_mnt_to, mnt_from, mp)) |
| 3101 | return -EINVAL; |
| 3102 | |
| 3103 | return 0; |
| 3104 | } |
| 3105 | |
| 3106 | static int do_move_mount(struct path *old_path, struct path *new_path, |
| 3107 | bool beneath) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3108 | { |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 3109 | struct mnt_namespace *ns; |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 3110 | struct mount *p; |
Al Viro | 0fb54e5 | 2011-11-24 19:59:16 -0500 | [diff] [blame] | 3111 | struct mount *old; |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3112 | struct mount *parent; |
| 3113 | struct mountpoint *mp, *old_mp; |
Al Viro | 57eccb8 | 2013-02-22 22:49:10 -0500 | [diff] [blame] | 3114 | int err; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 3115 | bool attached; |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 3116 | enum mnt_tree_flags_t flags = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3117 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 3118 | mp = do_lock_mount(new_path, beneath); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3119 | if (IS_ERR(mp)) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3120 | return PTR_ERR(mp); |
David Howells | cc53ce5 | 2011-01-14 18:45:26 +0000 | [diff] [blame] | 3121 | |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3122 | old = real_mount(old_path->mnt); |
| 3123 | p = real_mount(new_path->mnt); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3124 | parent = old->mnt_parent; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 3125 | attached = mnt_has_parent(old); |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 3126 | if (attached) |
| 3127 | flags |= MNT_TREE_MOVE; |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3128 | old_mp = old->mnt_mp; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 3129 | ns = old->mnt_ns; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 3130 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3131 | err = -EINVAL; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 3132 | /* The mountpoint must be in our namespace. */ |
| 3133 | if (!check_mnt(p)) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3134 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3135 | |
Eric Biggers | 570d7a9 | 2019-06-29 13:27:44 -0700 | [diff] [blame] | 3136 | /* The thing moved must be mounted... */ |
| 3137 | if (!is_mounted(&old->mnt)) |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 3138 | goto out; |
| 3139 | |
Eric Biggers | 570d7a9 | 2019-06-29 13:27:44 -0700 | [diff] [blame] | 3140 | /* ... and either ours or the root of anon namespace */ |
| 3141 | if (!(attached ? check_mnt(old) : is_anon_ns(ns))) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3142 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3143 | |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3144 | if (old->mnt.mnt_flags & MNT_LOCKED) |
| 3145 | goto out; |
| 3146 | |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 3147 | if (!path_mounted(old_path)) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3148 | goto out; |
| 3149 | |
| 3150 | if (d_is_dir(new_path->dentry) != |
| 3151 | d_is_dir(old_path->dentry)) |
| 3152 | goto out; |
Ram Pai | 2144440 | 2005-11-07 17:20:03 -0500 | [diff] [blame] | 3153 | /* |
| 3154 | * Don't move a mount residing in a shared parent. |
| 3155 | */ |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3156 | if (attached && IS_MNT_SHARED(parent)) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3157 | goto out; |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 3158 | |
| 3159 | if (beneath) { |
| 3160 | err = can_move_mount_beneath(old_path, new_path, mp); |
| 3161 | if (err) |
| 3162 | goto out; |
| 3163 | |
| 3164 | err = -EINVAL; |
| 3165 | p = p->mnt_parent; |
| 3166 | flags |= MNT_TREE_BENEATH; |
| 3167 | } |
| 3168 | |
Ram Pai | 9676f0c | 2005-11-07 17:21:20 -0500 | [diff] [blame] | 3169 | /* |
| 3170 | * Don't move a mount tree containing unbindable mounts to a destination |
| 3171 | * mount which is shared. |
| 3172 | */ |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 3173 | if (IS_MNT_SHARED(p) && tree_contains_unbindable(old)) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3174 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3175 | err = -ELOOP; |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 3176 | if (!check_for_nsfs_mounts(old)) |
| 3177 | goto out; |
Al Viro | fc7be13 | 2011-11-25 01:05:37 -0500 | [diff] [blame] | 3178 | for (; mnt_has_parent(p); p = p->mnt_parent) |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 3179 | if (p == old) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3180 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3181 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 3182 | err = attach_recursive_mnt(old, real_mount(new_path->mnt), mp, flags); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 3183 | if (err) |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3184 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3185 | |
| 3186 | /* if the mount is moved, it should no longer be expire |
| 3187 | * automatically */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3188 | list_del_init(&old->mnt_expire); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3189 | if (attached) |
| 3190 | put_mountpoint(old_mp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3191 | out: |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3192 | unlock_mount(mp); |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 3193 | if (!err) { |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 3194 | if (attached) |
| 3195 | mntput_no_expire(parent); |
| 3196 | else |
David Howells | 44dfd84 | 2018-11-05 17:40:31 +0000 | [diff] [blame] | 3197 | free_mnt_ns(ns); |
| 3198 | } |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 3199 | return err; |
| 3200 | } |
| 3201 | |
| 3202 | static int do_move_mount_old(struct path *path, const char *old_name) |
| 3203 | { |
| 3204 | struct path old_path; |
| 3205 | int err; |
| 3206 | |
| 3207 | if (!old_name || !*old_name) |
| 3208 | return -EINVAL; |
| 3209 | |
| 3210 | err = kern_path(old_name, LOOKUP_FOLLOW, &old_path); |
| 3211 | if (err) |
| 3212 | return err; |
| 3213 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 3214 | err = do_move_mount(&old_path, path, false); |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 3215 | path_put(&old_path); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3216 | return err; |
| 3217 | } |
| 3218 | |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3219 | /* |
| 3220 | * add a mount into a namespace's mount tree |
| 3221 | */ |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3222 | static int do_add_mount(struct mount *newmnt, struct mountpoint *mp, |
Al Viro | 1e2d8464 | 2021-06-18 20:27:57 -0400 | [diff] [blame] | 3223 | const struct path *path, int mnt_flags) |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3224 | { |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3225 | struct mount *parent = real_mount(path->mnt); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3226 | |
Al Viro | f2ebb3a | 2014-02-27 09:35:45 -0500 | [diff] [blame] | 3227 | mnt_flags &= ~MNT_INTERNAL_FLAGS; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3228 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3229 | if (unlikely(!check_mnt(parent))) { |
Al Viro | 156cacb | 2012-09-21 08:19:02 -0400 | [diff] [blame] | 3230 | /* that's acceptable only for automounts done in private ns */ |
| 3231 | if (!(mnt_flags & MNT_SHRINKABLE)) |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3232 | return -EINVAL; |
Al Viro | 156cacb | 2012-09-21 08:19:02 -0400 | [diff] [blame] | 3233 | /* ... and for those we'd better have mountpoint still alive */ |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 3234 | if (!parent->mnt_ns) |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3235 | return -EINVAL; |
Al Viro | 156cacb | 2012-09-21 08:19:02 -0400 | [diff] [blame] | 3236 | } |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3237 | |
| 3238 | /* Refuse the same filesystem on the same mount point */ |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 3239 | if (path->mnt->mnt_sb == newmnt->mnt.mnt_sb && path_mounted(path)) |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3240 | return -EBUSY; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3241 | |
David Howells | e36cb0b | 2015-01-29 12:02:35 +0000 | [diff] [blame] | 3242 | if (d_is_symlink(newmnt->mnt.mnt_root)) |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3243 | return -EINVAL; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3244 | |
Al Viro | 95bc5f2 | 2011-11-25 00:30:56 -0500 | [diff] [blame] | 3245 | newmnt->mnt.mnt_flags = mnt_flags; |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3246 | return graft_tree(newmnt, parent, mp); |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 3247 | } |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 3248 | |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 3249 | static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags); |
| 3250 | |
| 3251 | /* |
| 3252 | * Create a new mount using a superblock configuration and request it |
| 3253 | * be added to the namespace tree. |
| 3254 | */ |
| 3255 | static int do_new_mount_fc(struct fs_context *fc, struct path *mountpoint, |
| 3256 | unsigned int mnt_flags) |
| 3257 | { |
| 3258 | struct vfsmount *mnt; |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3259 | struct mountpoint *mp; |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 3260 | struct super_block *sb = fc->root->d_sb; |
| 3261 | int error; |
| 3262 | |
Al Viro | c9ce29e | 2018-12-20 15:04:50 -0500 | [diff] [blame] | 3263 | error = security_sb_kern_mount(sb); |
| 3264 | if (!error && mount_too_revealing(sb, &mnt_flags)) |
| 3265 | error = -EPERM; |
| 3266 | |
| 3267 | if (unlikely(error)) { |
| 3268 | fc_drop_locked(fc); |
| 3269 | return error; |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 3270 | } |
| 3271 | |
| 3272 | up_write(&sb->s_umount); |
| 3273 | |
| 3274 | mnt = vfs_create_mount(fc); |
| 3275 | if (IS_ERR(mnt)) |
| 3276 | return PTR_ERR(mnt); |
| 3277 | |
Deepa Dinamani | f8b92ba | 2019-04-15 14:17:12 -0700 | [diff] [blame] | 3278 | mnt_warn_timestamp_expiry(mountpoint, mnt); |
| 3279 | |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3280 | mp = lock_mount(mountpoint); |
| 3281 | if (IS_ERR(mp)) { |
| 3282 | mntput(mnt); |
| 3283 | return PTR_ERR(mp); |
| 3284 | } |
| 3285 | error = do_add_mount(real_mount(mnt), mp, mountpoint, mnt_flags); |
| 3286 | unlock_mount(mp); |
Eric Biggers | 0ecee66 | 2019-10-16 19:48:14 -0700 | [diff] [blame] | 3287 | if (error < 0) |
| 3288 | mntput(mnt); |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 3289 | return error; |
| 3290 | } |
Eric W. Biederman | 1b852bc | 2015-05-08 23:22:29 -0500 | [diff] [blame] | 3291 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3292 | /* |
| 3293 | * create a new mount for userspace and request it to be added into the |
| 3294 | * namespace's tree |
| 3295 | */ |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 3296 | static int do_new_mount(struct path *path, const char *fstype, int sb_flags, |
Al Viro | 808d4e3 | 2012-10-11 11:42:01 -0400 | [diff] [blame] | 3297 | int mnt_flags, const char *name, void *data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3298 | { |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 3299 | struct file_system_type *type; |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 3300 | struct fs_context *fc; |
| 3301 | const char *subtype = NULL; |
| 3302 | int err = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3303 | |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 3304 | if (!fstype) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3305 | return -EINVAL; |
| 3306 | |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 3307 | type = get_fs_type(fstype); |
| 3308 | if (!type) |
| 3309 | return -ENODEV; |
| 3310 | |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 3311 | if (type->fs_flags & FS_HAS_SUBTYPE) { |
| 3312 | subtype = strchr(fstype, '.'); |
| 3313 | if (subtype) { |
| 3314 | subtype++; |
| 3315 | if (!*subtype) { |
| 3316 | put_filesystem(type); |
| 3317 | return -EINVAL; |
| 3318 | } |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 3319 | } |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 3320 | } |
| 3321 | |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 3322 | fc = fs_context_for_mount(type, sb_flags); |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 3323 | put_filesystem(type); |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 3324 | if (IS_ERR(fc)) |
| 3325 | return PTR_ERR(fc); |
| 3326 | |
David Howells | 3e1aeb0 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 3327 | if (subtype) |
| 3328 | err = vfs_parse_fs_string(fc, "subtype", |
| 3329 | subtype, strlen(subtype)); |
| 3330 | if (!err && name) |
| 3331 | err = vfs_parse_fs_string(fc, "source", name, strlen(name)); |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 3332 | if (!err) |
| 3333 | err = parse_monolithic_mount_data(fc, data); |
Al Viro | c3aabf0 | 2019-05-13 12:57:22 -0400 | [diff] [blame] | 3334 | if (!err && !mount_capable(fc)) |
| 3335 | err = -EPERM; |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 3336 | if (!err) |
| 3337 | err = vfs_get_tree(fc); |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 3338 | if (!err) |
| 3339 | err = do_new_mount_fc(fc, path, mnt_flags); |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 3340 | |
Al Viro | a0c9a8b | 2018-11-04 07:18:51 -0500 | [diff] [blame] | 3341 | put_fs_context(fc); |
Al Viro | 15f9a3f | 2011-01-17 01:41:58 -0500 | [diff] [blame] | 3342 | return err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3343 | } |
| 3344 | |
Al Viro | 1e2d8464 | 2021-06-18 20:27:57 -0400 | [diff] [blame] | 3345 | int finish_automount(struct vfsmount *m, const struct path *path) |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 3346 | { |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 3347 | struct dentry *dentry = path->dentry; |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3348 | struct mountpoint *mp; |
Al Viro | 25e195a | 2020-01-11 11:27:46 -0500 | [diff] [blame] | 3349 | struct mount *mnt; |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 3350 | int err; |
Al Viro | 25e195a | 2020-01-11 11:27:46 -0500 | [diff] [blame] | 3351 | |
| 3352 | if (!m) |
| 3353 | return 0; |
| 3354 | if (IS_ERR(m)) |
| 3355 | return PTR_ERR(m); |
| 3356 | |
| 3357 | mnt = real_mount(m); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 3358 | /* The new mount record should have at least 2 refs to prevent it being |
| 3359 | * expired before we get a chance to add it |
| 3360 | */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3361 | BUG_ON(mnt_get_count(mnt) < 2); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 3362 | |
| 3363 | if (m->mnt_sb == path->mnt->mnt_sb && |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 3364 | m->mnt_root == dentry) { |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 3365 | err = -ELOOP; |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 3366 | goto discard; |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 3367 | } |
| 3368 | |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 3369 | /* |
| 3370 | * we don't want to use lock_mount() - in this case finding something |
| 3371 | * that overmounts our mountpoint to be means "quitely drop what we've |
| 3372 | * got", not "try to mount it on top". |
| 3373 | */ |
| 3374 | inode_lock(dentry->d_inode); |
| 3375 | namespace_lock(); |
| 3376 | if (unlikely(cant_mount(dentry))) { |
| 3377 | err = -ENOENT; |
| 3378 | goto discard_locked; |
| 3379 | } |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 3380 | if (path_overmounted(path)) { |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 3381 | err = 0; |
| 3382 | goto discard_locked; |
| 3383 | } |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 3384 | mp = get_mountpoint(dentry); |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3385 | if (IS_ERR(mp)) { |
| 3386 | err = PTR_ERR(mp); |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 3387 | goto discard_locked; |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3388 | } |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 3389 | |
Al Viro | 8f11538 | 2020-01-11 10:14:09 -0500 | [diff] [blame] | 3390 | err = do_add_mount(mnt, mp, path, path->mnt->mnt_flags | MNT_SHRINKABLE); |
| 3391 | unlock_mount(mp); |
Al Viro | 26df603 | 2020-01-11 10:44:29 -0500 | [diff] [blame] | 3392 | if (unlikely(err)) |
| 3393 | goto discard; |
| 3394 | mntput(m); |
| 3395 | return 0; |
| 3396 | |
| 3397 | discard_locked: |
| 3398 | namespace_unlock(); |
| 3399 | inode_unlock(dentry->d_inode); |
| 3400 | discard: |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 3401 | /* remove m from any expiration list it may be on */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3402 | if (!list_empty(&mnt->mnt_expire)) { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 3403 | namespace_lock(); |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3404 | list_del_init(&mnt->mnt_expire); |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 3405 | namespace_unlock(); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 3406 | } |
Al Viro | b1e75df | 2011-01-17 01:47:59 -0500 | [diff] [blame] | 3407 | mntput(m); |
| 3408 | mntput(m); |
Al Viro | 19a167a | 2011-01-17 01:35:23 -0500 | [diff] [blame] | 3409 | return err; |
| 3410 | } |
| 3411 | |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 3412 | /** |
| 3413 | * mnt_set_expiry - Put a mount on an expiration list |
| 3414 | * @mnt: The mount to list. |
| 3415 | * @expiry_list: The list to add the mount to. |
| 3416 | */ |
| 3417 | void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list) |
| 3418 | { |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 3419 | namespace_lock(); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 3420 | |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3421 | list_add_tail(&real_mount(mnt)->mnt_expire, expiry_list); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 3422 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 3423 | namespace_unlock(); |
David Howells | ea5b778 | 2011-01-14 19:10:03 +0000 | [diff] [blame] | 3424 | } |
| 3425 | EXPORT_SYMBOL(mnt_set_expiry); |
| 3426 | |
| 3427 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3428 | * process a list of expirable mountpoints with the intent of discarding any |
| 3429 | * mountpoints that aren't in use and haven't been touched since last we came |
| 3430 | * here |
| 3431 | */ |
| 3432 | void mark_mounts_for_expiry(struct list_head *mounts) |
| 3433 | { |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 3434 | struct mount *mnt, *next; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3435 | LIST_HEAD(graveyard); |
| 3436 | |
| 3437 | if (list_empty(mounts)) |
| 3438 | return; |
| 3439 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 3440 | namespace_lock(); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 3441 | lock_mount_hash(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3442 | |
| 3443 | /* extract from the expiration list every vfsmount that matches the |
| 3444 | * following criteria: |
| 3445 | * - only referenced by its parent vfsmount |
| 3446 | * - still marked for expiry (marked on the last call here; marks are |
| 3447 | * cleared by mntput()) |
| 3448 | */ |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3449 | list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { |
Al Viro | 863d684 | 2011-11-25 00:57:42 -0500 | [diff] [blame] | 3450 | if (!xchg(&mnt->mnt_expiry_mark, 1) || |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 3451 | propagate_mount_busy(mnt, 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3452 | continue; |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3453 | list_move(&mnt->mnt_expire, &graveyard); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3454 | } |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 3455 | while (!list_empty(&graveyard)) { |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3456 | mnt = list_first_entry(&graveyard, struct mount, mnt_expire); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 3457 | touch_mnt_namespace(mnt->mnt_ns); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 3458 | umount_tree(mnt, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 3459 | } |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 3460 | unlock_mount_hash(); |
Al Viro | 3ab6abe | 2013-03-16 14:42:19 -0400 | [diff] [blame] | 3461 | namespace_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3462 | } |
| 3463 | |
| 3464 | EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); |
| 3465 | |
| 3466 | /* |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3467 | * Ripoff of 'select_parent()' |
| 3468 | * |
| 3469 | * search the list of submounts for a given mountpoint, and move any |
| 3470 | * shrinkable submounts to the 'graveyard' list. |
| 3471 | */ |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 3472 | static int select_submounts(struct mount *parent, struct list_head *graveyard) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3473 | { |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 3474 | struct mount *this_parent = parent; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3475 | struct list_head *next; |
| 3476 | int found = 0; |
| 3477 | |
| 3478 | repeat: |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 3479 | next = this_parent->mnt_mounts.next; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3480 | resume: |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 3481 | while (next != &this_parent->mnt_mounts) { |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3482 | struct list_head *tmp = next; |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 3483 | struct mount *mnt = list_entry(tmp, struct mount, mnt_child); |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3484 | |
| 3485 | next = tmp->next; |
Al Viro | 692afc3 | 2011-11-24 21:15:14 -0500 | [diff] [blame] | 3486 | if (!(mnt->mnt.mnt_flags & MNT_SHRINKABLE)) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3487 | continue; |
| 3488 | /* |
| 3489 | * Descend a level if the d_mounts list is non-empty. |
| 3490 | */ |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 3491 | if (!list_empty(&mnt->mnt_mounts)) { |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3492 | this_parent = mnt; |
| 3493 | goto repeat; |
| 3494 | } |
| 3495 | |
Al Viro | 1ab5973 | 2011-11-24 21:35:16 -0500 | [diff] [blame] | 3496 | if (!propagate_mount_busy(mnt, 1)) { |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3497 | list_move_tail(&mnt->mnt_expire, graveyard); |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3498 | found++; |
| 3499 | } |
| 3500 | } |
| 3501 | /* |
| 3502 | * All done at this level ... ascend and resume the search |
| 3503 | */ |
| 3504 | if (this_parent != parent) { |
Al Viro | 6b41d53 | 2011-11-24 23:24:33 -0500 | [diff] [blame] | 3505 | next = this_parent->mnt_child.next; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 3506 | this_parent = this_parent->mnt_parent; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3507 | goto resume; |
| 3508 | } |
| 3509 | return found; |
| 3510 | } |
| 3511 | |
| 3512 | /* |
| 3513 | * process a list of expirable mountpoints with the intent of discarding any |
| 3514 | * submounts of a specific parent mountpoint |
Nick Piggin | 99b7db7 | 2010-08-18 04:37:39 +1000 | [diff] [blame] | 3515 | * |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 3516 | * mount_lock must be held for write |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3517 | */ |
Al Viro | b54b9be | 2013-03-16 14:39:34 -0400 | [diff] [blame] | 3518 | static void shrink_submounts(struct mount *mnt) |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3519 | { |
| 3520 | LIST_HEAD(graveyard); |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 3521 | struct mount *m; |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3522 | |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3523 | /* extract submounts of 'mountpoint' from the expiration list */ |
Al Viro | c35038b | 2008-03-22 00:46:23 -0400 | [diff] [blame] | 3524 | while (select_submounts(mnt, &graveyard)) { |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 3525 | while (!list_empty(&graveyard)) { |
Al Viro | 761d5c3 | 2011-11-24 21:07:43 -0500 | [diff] [blame] | 3526 | m = list_first_entry(&graveyard, struct mount, |
Al Viro | 6776db3d | 2011-11-25 00:22:05 -0500 | [diff] [blame] | 3527 | mnt_expire); |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 3528 | touch_mnt_namespace(m->mnt_ns); |
Eric W. Biederman | e819f15 | 2014-12-24 07:20:01 -0600 | [diff] [blame] | 3529 | umount_tree(m, UMOUNT_PROPAGATE|UMOUNT_SYNC); |
Al Viro | bcc5c7d | 2008-03-22 00:21:53 -0400 | [diff] [blame] | 3530 | } |
| 3531 | } |
Trond Myklebust | 5528f911 | 2006-06-09 09:34:17 -0400 | [diff] [blame] | 3532 | } |
| 3533 | |
Christoph Hellwig | 028abd9 | 2020-09-17 10:22:34 +0200 | [diff] [blame] | 3534 | static void *copy_mount_options(const void __user * data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3535 | { |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3536 | char *copy; |
Catalin Marinas | d563d67 | 2020-07-01 17:46:06 +0100 | [diff] [blame] | 3537 | unsigned left, offset; |
Ram Pai | b58fed8 | 2005-11-07 17:16:09 -0500 | [diff] [blame] | 3538 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3539 | if (!data) |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3540 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3541 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3542 | copy = kmalloc(PAGE_SIZE, GFP_KERNEL); |
| 3543 | if (!copy) |
| 3544 | return ERR_PTR(-ENOMEM); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3545 | |
Catalin Marinas | d563d67 | 2020-07-01 17:46:06 +0100 | [diff] [blame] | 3546 | left = copy_from_user(copy, data, PAGE_SIZE); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3547 | |
Catalin Marinas | d563d67 | 2020-07-01 17:46:06 +0100 | [diff] [blame] | 3548 | /* |
| 3549 | * Not all architectures have an exact copy_from_user(). Resort to |
| 3550 | * byte at a time. |
| 3551 | */ |
| 3552 | offset = PAGE_SIZE - left; |
| 3553 | while (left) { |
| 3554 | char c; |
| 3555 | if (get_user(c, (const char __user *)data + offset)) |
| 3556 | break; |
| 3557 | copy[offset] = c; |
| 3558 | left--; |
| 3559 | offset++; |
| 3560 | } |
| 3561 | |
| 3562 | if (left == PAGE_SIZE) { |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3563 | kfree(copy); |
| 3564 | return ERR_PTR(-EFAULT); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3565 | } |
Catalin Marinas | d563d67 | 2020-07-01 17:46:06 +0100 | [diff] [blame] | 3566 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3567 | return copy; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3568 | } |
| 3569 | |
Christoph Hellwig | 028abd9 | 2020-09-17 10:22:34 +0200 | [diff] [blame] | 3570 | static char *copy_mount_string(const void __user *data) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3571 | { |
Chandan Rajendra | fbdb440 | 2019-01-22 12:21:52 +0530 | [diff] [blame] | 3572 | return data ? strndup_user(data, PATH_MAX) : NULL; |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3573 | } |
| 3574 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3575 | /* |
| 3576 | * Flags is a 32-bit value that allows up to 31 non-fs dependent flags to |
| 3577 | * be given to the mount() call (ie: read-only, no-dev, no-suid etc). |
| 3578 | * |
| 3579 | * data is a (void *) that can point to any structure up to |
| 3580 | * PAGE_SIZE-1 bytes, which can contain arbitrary fs-dependent |
| 3581 | * information (or be NULL). |
| 3582 | * |
| 3583 | * Pre-0.97 versions of mount() didn't have a flags word. |
| 3584 | * When the flags word was introduced its top half was required |
| 3585 | * to have the magic value 0xC0ED, and this remained so until 2.4.0-test9. |
| 3586 | * Therefore, if this magic number is present, it carries no information |
| 3587 | * and must be discarded. |
| 3588 | */ |
Christoph Hellwig | c60166f | 2020-07-21 11:12:08 +0200 | [diff] [blame] | 3589 | int path_mount(const char *dev_name, struct path *path, |
Al Viro | 808d4e3 | 2012-10-11 11:42:01 -0400 | [diff] [blame] | 3590 | const char *type_page, unsigned long flags, void *data_page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3591 | { |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 3592 | unsigned int mnt_flags = 0, sb_flags; |
Christoph Hellwig | a1e6aaa | 2020-06-04 09:41:08 +0200 | [diff] [blame] | 3593 | int ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3594 | |
| 3595 | /* Discard magic */ |
| 3596 | if ((flags & MS_MGC_MSK) == MS_MGC_VAL) |
| 3597 | flags &= ~MS_MGC_MSK; |
| 3598 | |
| 3599 | /* Basic sanity checks */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3600 | if (data_page) |
| 3601 | ((char *)data_page)[PAGE_SIZE - 1] = 0; |
| 3602 | |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 3603 | if (flags & MS_NOUSER) |
| 3604 | return -EINVAL; |
| 3605 | |
Christoph Hellwig | a1e6aaa | 2020-06-04 09:41:08 +0200 | [diff] [blame] | 3606 | ret = security_sb_mount(dev_name, path, type_page, flags, data_page); |
| 3607 | if (ret) |
| 3608 | return ret; |
| 3609 | if (!may_mount()) |
| 3610 | return -EPERM; |
Jeff Layton | f7e33bd | 2021-08-19 14:56:38 -0400 | [diff] [blame] | 3611 | if (flags & SB_MANDLOCK) |
| 3612 | warn_mandlock(); |
Tetsuo Handa | a27ab9f2 | 2009-10-04 21:49:49 +0900 | [diff] [blame] | 3613 | |
Andi Kleen | 613cbe3 | 2009-04-19 18:40:43 +0200 | [diff] [blame] | 3614 | /* Default to relatime unless overriden */ |
| 3615 | if (!(flags & MS_NOATIME)) |
| 3616 | mnt_flags |= MNT_RELATIME; |
Matthew Garrett | 0a1c01c | 2009-03-26 17:53:14 +0000 | [diff] [blame] | 3617 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3618 | /* Separate the per-mountpoint flags */ |
| 3619 | if (flags & MS_NOSUID) |
| 3620 | mnt_flags |= MNT_NOSUID; |
| 3621 | if (flags & MS_NODEV) |
| 3622 | mnt_flags |= MNT_NODEV; |
| 3623 | if (flags & MS_NOEXEC) |
| 3624 | mnt_flags |= MNT_NOEXEC; |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 3625 | if (flags & MS_NOATIME) |
| 3626 | mnt_flags |= MNT_NOATIME; |
| 3627 | if (flags & MS_NODIRATIME) |
| 3628 | mnt_flags |= MNT_NODIRATIME; |
Matthew Garrett | d0adde5 | 2009-03-26 17:49:56 +0000 | [diff] [blame] | 3629 | if (flags & MS_STRICTATIME) |
| 3630 | mnt_flags &= ~(MNT_RELATIME | MNT_NOATIME); |
David Howells | a9e5b73 | 2018-04-20 13:35:02 +0100 | [diff] [blame] | 3631 | if (flags & MS_RDONLY) |
Dave Hansen | 2e4b7fc | 2008-02-15 14:38:00 -0800 | [diff] [blame] | 3632 | mnt_flags |= MNT_READONLY; |
Mattias Nissler | dab741e0 | 2020-08-27 11:09:46 -0600 | [diff] [blame] | 3633 | if (flags & MS_NOSYMFOLLOW) |
| 3634 | mnt_flags |= MNT_NOSYMFOLLOW; |
Christoph Hellwig | fc33a7b | 2006-01-09 20:52:17 -0800 | [diff] [blame] | 3635 | |
Eric W. Biederman | ffbc6f0 | 2014-07-28 17:36:04 -0700 | [diff] [blame] | 3636 | /* The default atime for remount is preservation */ |
| 3637 | if ((flags & MS_REMOUNT) && |
| 3638 | ((flags & (MS_NOATIME | MS_NODIRATIME | MS_RELATIME | |
| 3639 | MS_STRICTATIME)) == 0)) { |
| 3640 | mnt_flags &= ~MNT_ATIME_MASK; |
Christoph Hellwig | a1e6aaa | 2020-06-04 09:41:08 +0200 | [diff] [blame] | 3641 | mnt_flags |= path->mnt->mnt_flags & MNT_ATIME_MASK; |
Eric W. Biederman | ffbc6f0 | 2014-07-28 17:36:04 -0700 | [diff] [blame] | 3642 | } |
| 3643 | |
David Howells | e462ec5 | 2017-07-17 08:45:35 +0100 | [diff] [blame] | 3644 | sb_flags = flags & (SB_RDONLY | |
| 3645 | SB_SYNCHRONOUS | |
| 3646 | SB_MANDLOCK | |
| 3647 | SB_DIRSYNC | |
| 3648 | SB_SILENT | |
Mimi Zohar | 917086f | 2017-10-08 00:28:21 -0400 | [diff] [blame] | 3649 | SB_POSIXACL | |
Markus Trippelsdorf | d7ee946 | 2017-10-11 07:01:31 +0200 | [diff] [blame] | 3650 | SB_LAZYTIME | |
Mimi Zohar | 917086f | 2017-10-08 00:28:21 -0400 | [diff] [blame] | 3651 | SB_I_VERSION); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3652 | |
David Howells | 43f5e65 | 2018-11-01 23:07:25 +0000 | [diff] [blame] | 3653 | if ((flags & (MS_REMOUNT | MS_BIND)) == (MS_REMOUNT | MS_BIND)) |
Christoph Hellwig | a1e6aaa | 2020-06-04 09:41:08 +0200 | [diff] [blame] | 3654 | return do_reconfigure_mnt(path, mnt_flags); |
| 3655 | if (flags & MS_REMOUNT) |
| 3656 | return do_remount(path, flags, sb_flags, mnt_flags, data_page); |
| 3657 | if (flags & MS_BIND) |
| 3658 | return do_loopback(path, dev_name, flags & MS_REC); |
| 3659 | if (flags & (MS_SHARED | MS_PRIVATE | MS_SLAVE | MS_UNBINDABLE)) |
| 3660 | return do_change_type(path, flags); |
| 3661 | if (flags & MS_MOVE) |
| 3662 | return do_move_mount_old(path, dev_name); |
| 3663 | |
| 3664 | return do_new_mount(path, type_page, sb_flags, mnt_flags, dev_name, |
| 3665 | data_page); |
| 3666 | } |
| 3667 | |
| 3668 | long do_mount(const char *dev_name, const char __user *dir_name, |
| 3669 | const char *type_page, unsigned long flags, void *data_page) |
| 3670 | { |
| 3671 | struct path path; |
| 3672 | int ret; |
| 3673 | |
| 3674 | ret = user_path_at(AT_FDCWD, dir_name, LOOKUP_FOLLOW, &path); |
| 3675 | if (ret) |
| 3676 | return ret; |
| 3677 | ret = path_mount(dev_name, &path, type_page, flags, data_page); |
Al Viro | 2d92ab3 | 2008-08-02 00:51:11 -0400 | [diff] [blame] | 3678 | path_put(&path); |
Christoph Hellwig | a1e6aaa | 2020-06-04 09:41:08 +0200 | [diff] [blame] | 3679 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3680 | } |
| 3681 | |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3682 | static struct ucounts *inc_mnt_namespaces(struct user_namespace *ns) |
| 3683 | { |
| 3684 | return inc_ucount(ns, current_euid(), UCOUNT_MNT_NAMESPACES); |
| 3685 | } |
| 3686 | |
| 3687 | static void dec_mnt_namespaces(struct ucounts *ucounts) |
| 3688 | { |
| 3689 | dec_ucount(ucounts, UCOUNT_MNT_NAMESPACES); |
| 3690 | } |
| 3691 | |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 3692 | static void free_mnt_ns(struct mnt_namespace *ns) |
| 3693 | { |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3694 | if (!is_anon_ns(ns)) |
| 3695 | ns_free_inum(&ns->ns); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3696 | dec_mnt_namespaces(ns->ucounts); |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 3697 | put_user_ns(ns->user_ns); |
| 3698 | kfree(ns); |
| 3699 | } |
| 3700 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 3701 | /* |
| 3702 | * Assign a sequence number so we can detect when we attempt to bind |
| 3703 | * mount a reference to an older mount namespace into the current |
| 3704 | * mount namespace, preventing reference counting loops. A 64bit |
| 3705 | * number incrementing at 10Ghz will take 12,427 years to wrap which |
| 3706 | * is effectively never, so we can ignore the possibility. |
| 3707 | */ |
| 3708 | static atomic64_t mnt_ns_seq = ATOMIC64_INIT(1); |
| 3709 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3710 | static struct mnt_namespace *alloc_mnt_ns(struct user_namespace *user_ns, bool anon) |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3711 | { |
| 3712 | struct mnt_namespace *new_ns; |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3713 | struct ucounts *ucounts; |
Eric W. Biederman | 98f842e | 2011-06-15 10:21:48 -0700 | [diff] [blame] | 3714 | int ret; |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3715 | |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3716 | ucounts = inc_mnt_namespaces(user_ns); |
| 3717 | if (!ucounts) |
Eric W. Biederman | df75e77 | 2016-09-22 13:08:36 -0500 | [diff] [blame] | 3718 | return ERR_PTR(-ENOSPC); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3719 | |
Vasily Averin | 30acd0b | 2021-09-02 14:55:27 -0700 | [diff] [blame] | 3720 | new_ns = kzalloc(sizeof(struct mnt_namespace), GFP_KERNEL_ACCOUNT); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3721 | if (!new_ns) { |
| 3722 | dec_mnt_namespaces(ucounts); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3723 | return ERR_PTR(-ENOMEM); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3724 | } |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3725 | if (!anon) { |
| 3726 | ret = ns_alloc_inum(&new_ns->ns); |
| 3727 | if (ret) { |
| 3728 | kfree(new_ns); |
| 3729 | dec_mnt_namespaces(ucounts); |
| 3730 | return ERR_PTR(ret); |
| 3731 | } |
Eric W. Biederman | 98f842e | 2011-06-15 10:21:48 -0700 | [diff] [blame] | 3732 | } |
Al Viro | 33c4294 | 2014-11-01 02:32:53 -0400 | [diff] [blame] | 3733 | new_ns->ns.ops = &mntns_operations; |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3734 | if (!anon) |
| 3735 | new_ns->seq = atomic64_add_return(1, &mnt_ns_seq); |
Kirill Tkhai | 1a7b8969 | 2020-08-03 13:16:42 +0300 | [diff] [blame] | 3736 | refcount_set(&new_ns->ns.count, 1); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3737 | INIT_LIST_HEAD(&new_ns->list); |
| 3738 | init_waitqueue_head(&new_ns->poll); |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 3739 | spin_lock_init(&new_ns->ns_lock); |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 3740 | new_ns->user_ns = get_user_ns(user_ns); |
Eric W. Biederman | 537f7cc | 2016-08-08 14:37:37 -0500 | [diff] [blame] | 3741 | new_ns->ucounts = ucounts; |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3742 | return new_ns; |
| 3743 | } |
| 3744 | |
Emese Revfy | 0766f78 | 2016-06-20 20:42:34 +0200 | [diff] [blame] | 3745 | __latent_entropy |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3746 | struct mnt_namespace *copy_mnt_ns(unsigned long flags, struct mnt_namespace *ns, |
| 3747 | struct user_namespace *user_ns, struct fs_struct *new_fs) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3748 | { |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 3749 | struct mnt_namespace *new_ns; |
Al Viro | 7f2da1e | 2008-05-10 20:44:54 -0400 | [diff] [blame] | 3750 | struct vfsmount *rootmnt = NULL, *pwdmnt = NULL; |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 3751 | struct mount *p, *q; |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3752 | struct mount *old; |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 3753 | struct mount *new; |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 3754 | int copy_flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3755 | |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3756 | BUG_ON(!ns); |
| 3757 | |
| 3758 | if (likely(!(flags & CLONE_NEWNS))) { |
| 3759 | get_mnt_ns(ns); |
| 3760 | return ns; |
| 3761 | } |
| 3762 | |
| 3763 | old = ns->root; |
| 3764 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3765 | new_ns = alloc_mnt_ns(user_ns, false); |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3766 | if (IS_ERR(new_ns)) |
| 3767 | return new_ns; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3768 | |
Al Viro | 97216be | 2013-03-16 15:12:40 -0400 | [diff] [blame] | 3769 | namespace_lock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3770 | /* First pass: copy the tree topology */ |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 3771 | copy_flags = CL_COPY_UNBINDABLE | CL_EXPIRE; |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3772 | if (user_ns != ns->user_ns) |
Al Viro | 3bd045c | 2019-01-30 13:15:45 -0500 | [diff] [blame] | 3773 | copy_flags |= CL_SHARED_TO_SLAVE; |
Eric W. Biederman | 7a472ef | 2012-07-31 13:13:04 -0700 | [diff] [blame] | 3774 | new = copy_tree(old, old->mnt.mnt_root, copy_flags); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 3775 | if (IS_ERR(new)) { |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 3776 | namespace_unlock(); |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 3777 | free_mnt_ns(new_ns); |
David Howells | be34d1a | 2012-06-25 12:55:18 +0100 | [diff] [blame] | 3778 | return ERR_CAST(new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3779 | } |
Al Viro | 3bd045c | 2019-01-30 13:15:45 -0500 | [diff] [blame] | 3780 | if (user_ns != ns->user_ns) { |
| 3781 | lock_mount_hash(); |
| 3782 | lock_mnt_tree(new); |
| 3783 | unlock_mount_hash(); |
| 3784 | } |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 3785 | new_ns->root = new; |
Al Viro | 1a4eeaf | 2011-11-25 02:19:55 -0500 | [diff] [blame] | 3786 | list_add_tail(&new_ns->list, &new->mnt_list); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3787 | |
| 3788 | /* |
| 3789 | * Second pass: switch the tsk->fs->* elements and mark new vfsmounts |
| 3790 | * as belonging to new namespace. We have already acquired a private |
| 3791 | * fs_struct, so tsk->fs->lock is not needed. |
| 3792 | */ |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 3793 | p = old; |
Al Viro | cb338d0 | 2011-11-24 20:55:08 -0500 | [diff] [blame] | 3794 | q = new; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3795 | while (p) { |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 3796 | q->mnt_ns = new_ns; |
Eric W. Biederman | d292168 | 2016-09-28 00:27:17 -0500 | [diff] [blame] | 3797 | new_ns->mounts++; |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3798 | if (new_fs) { |
| 3799 | if (&p->mnt == new_fs->root.mnt) { |
| 3800 | new_fs->root.mnt = mntget(&q->mnt); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 3801 | rootmnt = &p->mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3802 | } |
Al Viro | 9559f68 | 2013-09-28 20:47:57 -0400 | [diff] [blame] | 3803 | if (&p->mnt == new_fs->pwd.mnt) { |
| 3804 | new_fs->pwd.mnt = mntget(&q->mnt); |
Al Viro | 315fc83 | 2011-11-24 18:57:30 -0500 | [diff] [blame] | 3805 | pwdmnt = &p->mnt; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3806 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3807 | } |
Al Viro | 909b0a8 | 2011-11-25 03:06:56 -0500 | [diff] [blame] | 3808 | p = next_mnt(p, old); |
| 3809 | q = next_mnt(q, new); |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 3810 | if (!q) |
| 3811 | break; |
Al Viro | 61d8e42 | 2022-11-24 22:55:57 -0500 | [diff] [blame] | 3812 | // an mntns binding we'd skipped? |
Eric W. Biederman | 4ce5d2b | 2013-03-30 01:35:18 -0700 | [diff] [blame] | 3813 | while (p->mnt.mnt_root != q->mnt.mnt_root) |
Al Viro | 61d8e42 | 2022-11-24 22:55:57 -0500 | [diff] [blame] | 3814 | p = next_mnt(skip_mnt_tree(p), old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3815 | } |
Al Viro | 328e6d9 | 2013-03-16 14:49:45 -0400 | [diff] [blame] | 3816 | namespace_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3817 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3818 | if (rootmnt) |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 3819 | mntput(rootmnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3820 | if (pwdmnt) |
Al Viro | f03c659 | 2011-01-14 22:30:21 -0500 | [diff] [blame] | 3821 | mntput(pwdmnt); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3822 | |
JANAK DESAI | 741a295 | 2006-02-07 12:59:00 -0800 | [diff] [blame] | 3823 | return new_ns; |
| 3824 | } |
| 3825 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3826 | struct dentry *mount_subtree(struct vfsmount *m, const char *name) |
Trond Myklebust | cf8d2c1 | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 3827 | { |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3828 | struct mount *mnt = real_mount(m); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3829 | struct mnt_namespace *ns; |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 3830 | struct super_block *s; |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3831 | struct path path; |
| 3832 | int err; |
| 3833 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3834 | ns = alloc_mnt_ns(&init_user_ns, true); |
| 3835 | if (IS_ERR(ns)) { |
| 3836 | mntput(m); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3837 | return ERR_CAST(ns); |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3838 | } |
| 3839 | mnt->mnt_ns = ns; |
| 3840 | ns->root = mnt; |
| 3841 | ns->mounts++; |
| 3842 | list_add(&mnt->mnt_list, &ns->list); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3843 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 3844 | err = vfs_path_lookup(m->mnt_root, m, |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3845 | name, LOOKUP_FOLLOW|LOOKUP_AUTOMOUNT, &path); |
| 3846 | |
| 3847 | put_mnt_ns(ns); |
| 3848 | |
| 3849 | if (err) |
| 3850 | return ERR_PTR(err); |
| 3851 | |
| 3852 | /* trade a vfsmount reference for active sb one */ |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 3853 | s = path.mnt->mnt_sb; |
| 3854 | atomic_inc(&s->s_active); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3855 | mntput(path.mnt); |
| 3856 | /* lock the sucker */ |
Al Viro | d31da0f | 2011-11-22 12:31:21 -0500 | [diff] [blame] | 3857 | down_write(&s->s_umount); |
Al Viro | ea441d1 | 2011-11-16 21:43:59 -0500 | [diff] [blame] | 3858 | /* ... and return the root of (sub)tree on it */ |
| 3859 | return path.dentry; |
| 3860 | } |
| 3861 | EXPORT_SYMBOL(mount_subtree); |
| 3862 | |
Dominik Brodowski | cccaa5e | 2018-10-23 22:41:09 +0200 | [diff] [blame] | 3863 | SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, |
| 3864 | char __user *, type, unsigned long, flags, void __user *, data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3865 | { |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3866 | int ret; |
| 3867 | char *kernel_type; |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3868 | char *kernel_dev; |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3869 | void *options; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3870 | |
Tim Gardner | b8850d1 | 2014-08-28 11:26:03 -0600 | [diff] [blame] | 3871 | kernel_type = copy_mount_string(type); |
| 3872 | ret = PTR_ERR(kernel_type); |
| 3873 | if (IS_ERR(kernel_type)) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3874 | goto out_type; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3875 | |
Tim Gardner | b8850d1 | 2014-08-28 11:26:03 -0600 | [diff] [blame] | 3876 | kernel_dev = copy_mount_string(dev_name); |
| 3877 | ret = PTR_ERR(kernel_dev); |
| 3878 | if (IS_ERR(kernel_dev)) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3879 | goto out_dev; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3880 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3881 | options = copy_mount_options(data); |
| 3882 | ret = PTR_ERR(options); |
| 3883 | if (IS_ERR(options)) |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3884 | goto out_data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3885 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3886 | ret = do_mount(kernel_dev, dir_name, kernel_type, flags, options); |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3887 | |
Al Viro | b40ef86 | 2015-12-14 18:44:44 -0500 | [diff] [blame] | 3888 | kfree(options); |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3889 | out_data: |
| 3890 | kfree(kernel_dev); |
| 3891 | out_dev: |
Vegard Nossum | eca6f53 | 2009-09-18 13:05:45 -0700 | [diff] [blame] | 3892 | kfree(kernel_type); |
| 3893 | out_type: |
| 3894 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3895 | } |
| 3896 | |
Christian Brauner | dd8b477 | 2021-06-01 11:33:59 +0200 | [diff] [blame] | 3897 | #define FSMOUNT_VALID_FLAGS \ |
| 3898 | (MOUNT_ATTR_RDONLY | MOUNT_ATTR_NOSUID | MOUNT_ATTR_NODEV | \ |
| 3899 | MOUNT_ATTR_NOEXEC | MOUNT_ATTR__ATIME | MOUNT_ATTR_NODIRATIME | \ |
| 3900 | MOUNT_ATTR_NOSYMFOLLOW) |
Christian Brauner | 5b49050 | 2021-01-21 14:19:52 +0100 | [diff] [blame] | 3901 | |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 3902 | #define MOUNT_SETATTR_VALID_FLAGS (FSMOUNT_VALID_FLAGS | MOUNT_ATTR_IDMAP) |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 3903 | |
| 3904 | #define MOUNT_SETATTR_PROPAGATION_FLAGS \ |
| 3905 | (MS_UNBINDABLE | MS_PRIVATE | MS_SLAVE | MS_SHARED) |
| 3906 | |
Christian Brauner | 5b49050 | 2021-01-21 14:19:52 +0100 | [diff] [blame] | 3907 | static unsigned int attr_flags_to_mnt_flags(u64 attr_flags) |
| 3908 | { |
| 3909 | unsigned int mnt_flags = 0; |
| 3910 | |
| 3911 | if (attr_flags & MOUNT_ATTR_RDONLY) |
| 3912 | mnt_flags |= MNT_READONLY; |
| 3913 | if (attr_flags & MOUNT_ATTR_NOSUID) |
| 3914 | mnt_flags |= MNT_NOSUID; |
| 3915 | if (attr_flags & MOUNT_ATTR_NODEV) |
| 3916 | mnt_flags |= MNT_NODEV; |
| 3917 | if (attr_flags & MOUNT_ATTR_NOEXEC) |
| 3918 | mnt_flags |= MNT_NOEXEC; |
| 3919 | if (attr_flags & MOUNT_ATTR_NODIRATIME) |
| 3920 | mnt_flags |= MNT_NODIRATIME; |
Christian Brauner | dd8b477 | 2021-06-01 11:33:59 +0200 | [diff] [blame] | 3921 | if (attr_flags & MOUNT_ATTR_NOSYMFOLLOW) |
| 3922 | mnt_flags |= MNT_NOSYMFOLLOW; |
Christian Brauner | 5b49050 | 2021-01-21 14:19:52 +0100 | [diff] [blame] | 3923 | |
| 3924 | return mnt_flags; |
| 3925 | } |
| 3926 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3927 | /* |
David Howells | 93766fb | 2018-11-01 23:36:14 +0000 | [diff] [blame] | 3928 | * Create a kernel mount representation for a new, prepared superblock |
| 3929 | * (specified by fs_fd) and attach to an open_tree-like file descriptor. |
| 3930 | */ |
| 3931 | SYSCALL_DEFINE3(fsmount, int, fs_fd, unsigned int, flags, |
| 3932 | unsigned int, attr_flags) |
| 3933 | { |
| 3934 | struct mnt_namespace *ns; |
| 3935 | struct fs_context *fc; |
| 3936 | struct file *file; |
| 3937 | struct path newmount; |
| 3938 | struct mount *mnt; |
| 3939 | struct fd f; |
| 3940 | unsigned int mnt_flags = 0; |
| 3941 | long ret; |
| 3942 | |
| 3943 | if (!may_mount()) |
| 3944 | return -EPERM; |
| 3945 | |
| 3946 | if ((flags & ~(FSMOUNT_CLOEXEC)) != 0) |
| 3947 | return -EINVAL; |
| 3948 | |
Christian Brauner | 5b49050 | 2021-01-21 14:19:52 +0100 | [diff] [blame] | 3949 | if (attr_flags & ~FSMOUNT_VALID_FLAGS) |
David Howells | 93766fb | 2018-11-01 23:36:14 +0000 | [diff] [blame] | 3950 | return -EINVAL; |
| 3951 | |
Christian Brauner | 5b49050 | 2021-01-21 14:19:52 +0100 | [diff] [blame] | 3952 | mnt_flags = attr_flags_to_mnt_flags(attr_flags); |
David Howells | 93766fb | 2018-11-01 23:36:14 +0000 | [diff] [blame] | 3953 | |
| 3954 | switch (attr_flags & MOUNT_ATTR__ATIME) { |
| 3955 | case MOUNT_ATTR_STRICTATIME: |
| 3956 | break; |
| 3957 | case MOUNT_ATTR_NOATIME: |
| 3958 | mnt_flags |= MNT_NOATIME; |
| 3959 | break; |
| 3960 | case MOUNT_ATTR_RELATIME: |
| 3961 | mnt_flags |= MNT_RELATIME; |
| 3962 | break; |
| 3963 | default: |
| 3964 | return -EINVAL; |
| 3965 | } |
| 3966 | |
| 3967 | f = fdget(fs_fd); |
| 3968 | if (!f.file) |
| 3969 | return -EBADF; |
| 3970 | |
| 3971 | ret = -EINVAL; |
| 3972 | if (f.file->f_op != &fscontext_fops) |
| 3973 | goto err_fsfd; |
| 3974 | |
| 3975 | fc = f.file->private_data; |
| 3976 | |
| 3977 | ret = mutex_lock_interruptible(&fc->uapi_mutex); |
| 3978 | if (ret < 0) |
| 3979 | goto err_fsfd; |
| 3980 | |
| 3981 | /* There must be a valid superblock or we can't mount it */ |
| 3982 | ret = -EINVAL; |
| 3983 | if (!fc->root) |
| 3984 | goto err_unlock; |
| 3985 | |
| 3986 | ret = -EPERM; |
| 3987 | if (mount_too_revealing(fc->root->d_sb, &mnt_flags)) { |
| 3988 | pr_warn("VFS: Mount too revealing\n"); |
| 3989 | goto err_unlock; |
| 3990 | } |
| 3991 | |
| 3992 | ret = -EBUSY; |
| 3993 | if (fc->phase != FS_CONTEXT_AWAITING_MOUNT) |
| 3994 | goto err_unlock; |
| 3995 | |
Jeff Layton | f7e33bd | 2021-08-19 14:56:38 -0400 | [diff] [blame] | 3996 | if (fc->sb_flags & SB_MANDLOCK) |
| 3997 | warn_mandlock(); |
David Howells | 93766fb | 2018-11-01 23:36:14 +0000 | [diff] [blame] | 3998 | |
| 3999 | newmount.mnt = vfs_create_mount(fc); |
| 4000 | if (IS_ERR(newmount.mnt)) { |
| 4001 | ret = PTR_ERR(newmount.mnt); |
| 4002 | goto err_unlock; |
| 4003 | } |
| 4004 | newmount.dentry = dget(fc->root); |
| 4005 | newmount.mnt->mnt_flags = mnt_flags; |
| 4006 | |
| 4007 | /* We've done the mount bit - now move the file context into more or |
| 4008 | * less the same state as if we'd done an fspick(). We don't want to |
| 4009 | * do any memory allocation or anything like that at this point as we |
| 4010 | * don't want to have to handle any errors incurred. |
| 4011 | */ |
| 4012 | vfs_clean_context(fc); |
| 4013 | |
| 4014 | ns = alloc_mnt_ns(current->nsproxy->mnt_ns->user_ns, true); |
| 4015 | if (IS_ERR(ns)) { |
| 4016 | ret = PTR_ERR(ns); |
| 4017 | goto err_path; |
| 4018 | } |
| 4019 | mnt = real_mount(newmount.mnt); |
| 4020 | mnt->mnt_ns = ns; |
| 4021 | ns->root = mnt; |
| 4022 | ns->mounts = 1; |
| 4023 | list_add(&mnt->mnt_list, &ns->list); |
Eric Biggers | 1b0b9cc | 2019-06-12 11:43:13 -0700 | [diff] [blame] | 4024 | mntget(newmount.mnt); |
David Howells | 93766fb | 2018-11-01 23:36:14 +0000 | [diff] [blame] | 4025 | |
| 4026 | /* Attach to an apparent O_PATH fd with a note that we need to unmount |
| 4027 | * it, not just simply put it. |
| 4028 | */ |
| 4029 | file = dentry_open(&newmount, O_PATH, fc->cred); |
| 4030 | if (IS_ERR(file)) { |
| 4031 | dissolve_on_fput(newmount.mnt); |
| 4032 | ret = PTR_ERR(file); |
| 4033 | goto err_path; |
| 4034 | } |
| 4035 | file->f_mode |= FMODE_NEED_UNMOUNT; |
| 4036 | |
| 4037 | ret = get_unused_fd_flags((flags & FSMOUNT_CLOEXEC) ? O_CLOEXEC : 0); |
| 4038 | if (ret >= 0) |
| 4039 | fd_install(ret, file); |
| 4040 | else |
| 4041 | fput(file); |
| 4042 | |
| 4043 | err_path: |
| 4044 | path_put(&newmount); |
| 4045 | err_unlock: |
| 4046 | mutex_unlock(&fc->uapi_mutex); |
| 4047 | err_fsfd: |
| 4048 | fdput(f); |
| 4049 | return ret; |
| 4050 | } |
| 4051 | |
| 4052 | /* |
| 4053 | * Move a mount from one place to another. In combination with |
| 4054 | * fsopen()/fsmount() this is used to install a new mount and in combination |
| 4055 | * with open_tree(OPEN_TREE_CLONE [| AT_RECURSIVE]) it can be used to copy |
| 4056 | * a mount subtree. |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 4057 | * |
| 4058 | * Note the flags value is a combination of MOVE_MOUNT_* flags. |
| 4059 | */ |
| 4060 | SYSCALL_DEFINE5(move_mount, |
Ben Dooks | 2658ce0 | 2019-10-15 11:35:02 +0100 | [diff] [blame] | 4061 | int, from_dfd, const char __user *, from_pathname, |
| 4062 | int, to_dfd, const char __user *, to_pathname, |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 4063 | unsigned int, flags) |
| 4064 | { |
| 4065 | struct path from_path, to_path; |
| 4066 | unsigned int lflags; |
| 4067 | int ret = 0; |
| 4068 | |
| 4069 | if (!may_mount()) |
| 4070 | return -EPERM; |
| 4071 | |
| 4072 | if (flags & ~MOVE_MOUNT__MASK) |
| 4073 | return -EINVAL; |
| 4074 | |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 4075 | if ((flags & (MOVE_MOUNT_BENEATH | MOVE_MOUNT_SET_GROUP)) == |
| 4076 | (MOVE_MOUNT_BENEATH | MOVE_MOUNT_SET_GROUP)) |
| 4077 | return -EINVAL; |
| 4078 | |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 4079 | /* If someone gives a pathname, they aren't permitted to move |
| 4080 | * from an fd that requires unmount as we can't get at the flag |
| 4081 | * to clear it afterwards. |
| 4082 | */ |
| 4083 | lflags = 0; |
| 4084 | if (flags & MOVE_MOUNT_F_SYMLINKS) lflags |= LOOKUP_FOLLOW; |
| 4085 | if (flags & MOVE_MOUNT_F_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT; |
| 4086 | if (flags & MOVE_MOUNT_F_EMPTY_PATH) lflags |= LOOKUP_EMPTY; |
| 4087 | |
| 4088 | ret = user_path_at(from_dfd, from_pathname, lflags, &from_path); |
| 4089 | if (ret < 0) |
| 4090 | return ret; |
| 4091 | |
| 4092 | lflags = 0; |
| 4093 | if (flags & MOVE_MOUNT_T_SYMLINKS) lflags |= LOOKUP_FOLLOW; |
| 4094 | if (flags & MOVE_MOUNT_T_AUTOMOUNTS) lflags |= LOOKUP_AUTOMOUNT; |
| 4095 | if (flags & MOVE_MOUNT_T_EMPTY_PATH) lflags |= LOOKUP_EMPTY; |
| 4096 | |
| 4097 | ret = user_path_at(to_dfd, to_pathname, lflags, &to_path); |
| 4098 | if (ret < 0) |
| 4099 | goto out_from; |
| 4100 | |
| 4101 | ret = security_move_mount(&from_path, &to_path); |
| 4102 | if (ret < 0) |
| 4103 | goto out_to; |
| 4104 | |
Pavel Tikhomirov | 9ffb14e | 2021-07-15 13:07:13 +0300 | [diff] [blame] | 4105 | if (flags & MOVE_MOUNT_SET_GROUP) |
| 4106 | ret = do_set_group(&from_path, &to_path); |
| 4107 | else |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 4108 | ret = do_move_mount(&from_path, &to_path, |
| 4109 | (flags & MOVE_MOUNT_BENEATH)); |
David Howells | 2db154b | 2018-11-05 17:40:30 +0000 | [diff] [blame] | 4110 | |
| 4111 | out_to: |
| 4112 | path_put(&to_path); |
| 4113 | out_from: |
| 4114 | path_put(&from_path); |
| 4115 | return ret; |
| 4116 | } |
| 4117 | |
| 4118 | /* |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 4119 | * Return true if path is reachable from root |
| 4120 | * |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 4121 | * namespace_sem or mount_lock is held |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 4122 | */ |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 4123 | bool is_path_reachable(struct mount *mnt, struct dentry *dentry, |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 4124 | const struct path *root) |
| 4125 | { |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 4126 | while (&mnt->mnt != root->mnt && mnt_has_parent(mnt)) { |
Al Viro | a73324d | 2011-11-24 22:25:07 -0500 | [diff] [blame] | 4127 | dentry = mnt->mnt_mountpoint; |
Al Viro | 0714a53 | 2011-11-24 22:19:58 -0500 | [diff] [blame] | 4128 | mnt = mnt->mnt_parent; |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 4129 | } |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 4130 | return &mnt->mnt == root->mnt && is_subdir(dentry, root->dentry); |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 4131 | } |
| 4132 | |
Mickaël Salaün | 640eb7e | 2016-11-14 22:14:35 +0100 | [diff] [blame] | 4133 | bool path_is_under(const struct path *path1, const struct path *path2) |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 4134 | { |
Yaowei Bai | 25ab4c9 | 2015-11-17 14:40:10 +0800 | [diff] [blame] | 4135 | bool res; |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 4136 | read_seqlock_excl(&mount_lock); |
Al Viro | 643822b | 2011-11-24 22:00:28 -0500 | [diff] [blame] | 4137 | res = is_path_reachable(real_mount(path1->mnt), path1->dentry, path2); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 4138 | read_sequnlock_excl(&mount_lock); |
Al Viro | afac7cb | 2011-11-23 19:34:49 -0500 | [diff] [blame] | 4139 | return res; |
| 4140 | } |
| 4141 | EXPORT_SYMBOL(path_is_under); |
| 4142 | |
| 4143 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4144 | * pivot_root Semantics: |
| 4145 | * Moves the root file system of the current process to the directory put_old, |
| 4146 | * makes new_root as the new root file system of the current process, and sets |
| 4147 | * root/cwd of all processes which had them on the current root to new_root. |
| 4148 | * |
| 4149 | * Restrictions: |
| 4150 | * The new_root and put_old must be directories, and must not be on the |
| 4151 | * same file system as the current process root. The put_old must be |
| 4152 | * underneath new_root, i.e. adding a non-zero number of /.. to the string |
| 4153 | * pointed to by put_old must yield the same directory as new_root. No other |
| 4154 | * file system may be mounted on put_old. After all, new_root is a mountpoint. |
| 4155 | * |
Neil Brown | 4a0d11f | 2006-01-08 01:03:18 -0800 | [diff] [blame] | 4156 | * Also, the current root cannot be on the 'rootfs' (initial ramfs) filesystem. |
Mauro Carvalho Chehab | 0c1bc6b | 2020-04-14 18:48:37 +0200 | [diff] [blame] | 4157 | * See Documentation/filesystems/ramfs-rootfs-initramfs.rst for alternatives |
Neil Brown | 4a0d11f | 2006-01-08 01:03:18 -0800 | [diff] [blame] | 4158 | * in this situation. |
| 4159 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4160 | * Notes: |
| 4161 | * - we don't move root/cwd if they are not at the root (reason: if something |
| 4162 | * cared enough to change them, it's probably wrong to force them elsewhere) |
| 4163 | * - it's okay to pick a root that isn't the root of a file system, e.g. |
| 4164 | * /nfs/my_root where /nfs is the mount point. It must be a mountpoint, |
| 4165 | * though, so you may need to say mount --bind /nfs/my_root /nfs/my_root |
| 4166 | * first. |
| 4167 | */ |
Heiko Carstens | 3480b25 | 2009-01-14 14:14:16 +0100 | [diff] [blame] | 4168 | SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, |
| 4169 | const char __user *, put_old) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4170 | { |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 4171 | struct path new, old, root; |
| 4172 | struct mount *new_mnt, *root_mnt, *old_mnt, *root_parent, *ex_parent; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 4173 | struct mountpoint *old_mp, *root_mp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4174 | int error; |
| 4175 | |
Al Viro | 9b40bc9 | 2013-02-22 22:45:42 -0500 | [diff] [blame] | 4176 | if (!may_mount()) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4177 | return -EPERM; |
| 4178 | |
Al Viro | ce6595a | 2019-07-14 16:42:44 -0400 | [diff] [blame] | 4179 | error = user_path_at(AT_FDCWD, new_root, |
| 4180 | LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4181 | if (error) |
| 4182 | goto out0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4183 | |
Al Viro | ce6595a | 2019-07-14 16:42:44 -0400 | [diff] [blame] | 4184 | error = user_path_at(AT_FDCWD, put_old, |
| 4185 | LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4186 | if (error) |
| 4187 | goto out1; |
| 4188 | |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 4189 | error = security_sb_pivotroot(&old, &new); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4190 | if (error) |
| 4191 | goto out2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4192 | |
Miklos Szeredi | f7ad3c6 | 2010-08-10 11:41:36 +0200 | [diff] [blame] | 4193 | get_fs_root(current->fs, &root); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 4194 | old_mp = lock_mount(&old); |
| 4195 | error = PTR_ERR(old_mp); |
| 4196 | if (IS_ERR(old_mp)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4197 | goto out3; |
| 4198 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4199 | error = -EINVAL; |
Al Viro | 419148d | 2011-11-24 19:41:16 -0500 | [diff] [blame] | 4200 | new_mnt = real_mount(new.mnt); |
| 4201 | root_mnt = real_mount(root.mnt); |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 4202 | old_mnt = real_mount(old.mnt); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 4203 | ex_parent = new_mnt->mnt_parent; |
| 4204 | root_parent = root_mnt->mnt_parent; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 4205 | if (IS_MNT_SHARED(old_mnt) || |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 4206 | IS_MNT_SHARED(ex_parent) || |
| 4207 | IS_MNT_SHARED(root_parent)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4208 | goto out4; |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 4209 | if (!check_mnt(root_mnt) || !check_mnt(new_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4210 | goto out4; |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 4211 | if (new_mnt->mnt.mnt_flags & MNT_LOCKED) |
| 4212 | goto out4; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4213 | error = -ENOENT; |
Alexey Dobriyan | f3da392 | 2009-05-04 03:32:03 +0400 | [diff] [blame] | 4214 | if (d_unlinked(new.dentry)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4215 | goto out4; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4216 | error = -EBUSY; |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 4217 | if (new_mnt == root_mnt || old_mnt == root_mnt) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4218 | goto out4; /* loop, on the same file system */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4219 | error = -EINVAL; |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 4220 | if (!path_mounted(&root)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4221 | goto out4; /* not a mountpoint */ |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 4222 | if (!mnt_has_parent(root_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4223 | goto out4; /* not attached */ |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 4224 | if (!path_mounted(&new)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4225 | goto out4; /* not a mountpoint */ |
Al Viro | 676da58 | 2011-11-24 21:47:05 -0500 | [diff] [blame] | 4226 | if (!mnt_has_parent(new_mnt)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4227 | goto out4; /* not attached */ |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 4228 | /* make sure we can reach put_old from new_root */ |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 4229 | if (!is_path_reachable(old_mnt, old.dentry, &new)) |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4230 | goto out4; |
Eric W. Biederman | 0d08260 | 2014-10-08 10:42:27 -0700 | [diff] [blame] | 4231 | /* make certain new is below the root */ |
| 4232 | if (!is_path_reachable(new_mnt, new.dentry, &root)) |
| 4233 | goto out4; |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 4234 | lock_mount_hash(); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 4235 | umount_mnt(new_mnt); |
| 4236 | root_mp = unhash_mnt(root_mnt); /* we'll need its mountpoint */ |
Eric W. Biederman | 5ff9d8a | 2013-03-29 21:04:39 -0700 | [diff] [blame] | 4237 | if (root_mnt->mnt.mnt_flags & MNT_LOCKED) { |
| 4238 | new_mnt->mnt.mnt_flags |= MNT_LOCKED; |
| 4239 | root_mnt->mnt.mnt_flags &= ~MNT_LOCKED; |
| 4240 | } |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 4241 | /* mount old root on put_old */ |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 4242 | attach_mnt(root_mnt, old_mnt, old_mp, false); |
Jan Blunck | 4ac9137 | 2008-02-14 19:34:32 -0800 | [diff] [blame] | 4243 | /* mount new_root on / */ |
Christian Brauner | 6ac3928 | 2023-05-03 13:18:42 +0200 | [diff] [blame] | 4244 | attach_mnt(new_mnt, root_parent, root_mp, false); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 4245 | mnt_add_count(root_parent, -1); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 4246 | touch_mnt_namespace(current->nsproxy->mnt_ns); |
Eric W. Biederman | 4fed655 | 2014-10-08 10:42:57 -0700 | [diff] [blame] | 4247 | /* A moved mount should not expire automatically */ |
| 4248 | list_del_init(&new_mnt->mnt_expire); |
Eric W. Biederman | 3895dbf | 2017-01-03 14:18:43 +1300 | [diff] [blame] | 4249 | put_mountpoint(root_mp); |
Al Viro | 719ea2f | 2013-09-29 11:24:49 -0400 | [diff] [blame] | 4250 | unlock_mount_hash(); |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 4251 | chroot_fs_refs(&root, &new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4252 | error = 0; |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4253 | out4: |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 4254 | unlock_mount(old_mp); |
Al Viro | 2763d11 | 2019-06-30 19:18:53 -0400 | [diff] [blame] | 4255 | if (!error) |
| 4256 | mntput_no_expire(ex_parent); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4257 | out3: |
Al Viro | 8c3ee42 | 2008-03-22 18:00:39 -0400 | [diff] [blame] | 4258 | path_put(&root); |
Al Viro | b12cea9 | 2011-03-18 08:55:38 -0400 | [diff] [blame] | 4259 | out2: |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 4260 | path_put(&old); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4261 | out1: |
Al Viro | 2d8f303 | 2008-07-22 09:59:21 -0400 | [diff] [blame] | 4262 | path_put(&new); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4263 | out0: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4264 | return error; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4265 | } |
| 4266 | |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4267 | static unsigned int recalc_flags(struct mount_kattr *kattr, struct mount *mnt) |
| 4268 | { |
| 4269 | unsigned int flags = mnt->mnt.mnt_flags; |
| 4270 | |
| 4271 | /* flags to clear */ |
| 4272 | flags &= ~kattr->attr_clr; |
| 4273 | /* flags to raise */ |
| 4274 | flags |= kattr->attr_set; |
| 4275 | |
| 4276 | return flags; |
| 4277 | } |
| 4278 | |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4279 | static int can_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) |
| 4280 | { |
| 4281 | struct vfsmount *m = &mnt->mnt; |
Christian Brauner | bd30336 | 2021-12-03 12:17:07 +0100 | [diff] [blame] | 4282 | struct user_namespace *fs_userns = m->mnt_sb->s_user_ns; |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4283 | |
Christian Brauner | 256c8ae | 2022-10-26 12:51:27 +0200 | [diff] [blame] | 4284 | if (!kattr->mnt_idmap) |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4285 | return 0; |
| 4286 | |
| 4287 | /* |
Christian Brauner | bd30336 | 2021-12-03 12:17:07 +0100 | [diff] [blame] | 4288 | * Creating an idmapped mount with the filesystem wide idmapping |
| 4289 | * doesn't make sense so block that. We don't allow mushy semantics. |
| 4290 | */ |
Christian Brauner | 3707d84 | 2023-01-13 12:49:33 +0100 | [diff] [blame] | 4291 | if (!check_fsmapping(kattr->mnt_idmap, m->mnt_sb)) |
Christian Brauner | bd30336 | 2021-12-03 12:17:07 +0100 | [diff] [blame] | 4292 | return -EINVAL; |
| 4293 | |
| 4294 | /* |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4295 | * Once a mount has been idmapped we don't allow it to change its |
| 4296 | * mapping. It makes things simpler and callers can just create |
| 4297 | * another bind-mount they can idmap if they want to. |
| 4298 | */ |
Christian Brauner | bb49e9e | 2021-12-03 12:16:58 +0100 | [diff] [blame] | 4299 | if (is_idmapped_mnt(m)) |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4300 | return -EPERM; |
| 4301 | |
| 4302 | /* The underlying filesystem doesn't support idmapped mounts yet. */ |
| 4303 | if (!(m->mnt_sb->s_type->fs_flags & FS_ALLOW_IDMAP)) |
| 4304 | return -EINVAL; |
| 4305 | |
| 4306 | /* We're not controlling the superblock. */ |
Christian Brauner | bd30336 | 2021-12-03 12:17:07 +0100 | [diff] [blame] | 4307 | if (!ns_capable(fs_userns, CAP_SYS_ADMIN)) |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4308 | return -EPERM; |
| 4309 | |
| 4310 | /* Mount has already been visible in the filesystem hierarchy. */ |
| 4311 | if (!is_anon_ns(mnt->mnt_ns)) |
| 4312 | return -EINVAL; |
| 4313 | |
| 4314 | return 0; |
| 4315 | } |
| 4316 | |
Christian Brauner | a26f788 | 2022-02-03 14:14:08 +0100 | [diff] [blame] | 4317 | /** |
| 4318 | * mnt_allow_writers() - check whether the attribute change allows writers |
| 4319 | * @kattr: the new mount attributes |
| 4320 | * @mnt: the mount to which @kattr will be applied |
| 4321 | * |
| 4322 | * Check whether thew new mount attributes in @kattr allow concurrent writers. |
| 4323 | * |
| 4324 | * Return: true if writers need to be held, false if not |
| 4325 | */ |
| 4326 | static inline bool mnt_allow_writers(const struct mount_kattr *kattr, |
| 4327 | const struct mount *mnt) |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4328 | { |
Christian Brauner | e1bbcd2 | 2022-05-10 11:58:40 +0200 | [diff] [blame] | 4329 | return (!(kattr->attr_set & MNT_READONLY) || |
| 4330 | (mnt->mnt.mnt_flags & MNT_READONLY)) && |
Christian Brauner | 256c8ae | 2022-10-26 12:51:27 +0200 | [diff] [blame] | 4331 | !kattr->mnt_idmap; |
Christian Brauner | a26f788 | 2022-02-03 14:14:08 +0100 | [diff] [blame] | 4332 | } |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4333 | |
Christian Brauner | 87bb5b6 | 2022-02-03 14:14:11 +0100 | [diff] [blame] | 4334 | static int mount_setattr_prepare(struct mount_kattr *kattr, struct mount *mnt) |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4335 | { |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4336 | struct mount *m; |
| 4337 | int err; |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4338 | |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4339 | for (m = mnt; m; m = next_mnt(m, mnt)) { |
| 4340 | if (!can_change_locked_flags(m, recalc_flags(kattr, m))) { |
| 4341 | err = -EPERM; |
| 4342 | break; |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4343 | } |
| 4344 | |
Christian Brauner | 87bb5b6 | 2022-02-03 14:14:11 +0100 | [diff] [blame] | 4345 | err = can_idmap_mount(kattr, m); |
| 4346 | if (err) |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4347 | break; |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4348 | |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4349 | if (!mnt_allow_writers(kattr, m)) { |
| 4350 | err = mnt_hold_writers(m); |
| 4351 | if (err) |
| 4352 | break; |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4353 | } |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4354 | |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4355 | if (!kattr->recurse) |
| 4356 | return 0; |
| 4357 | } |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4358 | |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4359 | if (err) { |
| 4360 | struct mount *p; |
| 4361 | |
Christian Brauner | 0014eda | 2022-04-20 15:19:25 +0200 | [diff] [blame] | 4362 | /* |
| 4363 | * If we had to call mnt_hold_writers() MNT_WRITE_HOLD will |
| 4364 | * be set in @mnt_flags. The loop unsets MNT_WRITE_HOLD for all |
| 4365 | * mounts and needs to take care to include the first mount. |
| 4366 | */ |
| 4367 | for (p = mnt; p; p = next_mnt(p, mnt)) { |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4368 | /* If we had to hold writers unblock them. */ |
| 4369 | if (p->mnt.mnt_flags & MNT_WRITE_HOLD) |
| 4370 | mnt_unhold_writers(p); |
Christian Brauner | 0014eda | 2022-04-20 15:19:25 +0200 | [diff] [blame] | 4371 | |
| 4372 | /* |
| 4373 | * We're done once the first mount we changed got |
| 4374 | * MNT_WRITE_HOLD unset. |
| 4375 | */ |
| 4376 | if (p == m) |
| 4377 | break; |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4378 | } |
| 4379 | } |
| 4380 | return err; |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4381 | } |
| 4382 | |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4383 | static void do_idmap_mount(const struct mount_kattr *kattr, struct mount *mnt) |
| 4384 | { |
Christian Brauner | 256c8ae | 2022-10-26 12:51:27 +0200 | [diff] [blame] | 4385 | if (!kattr->mnt_idmap) |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4386 | return; |
| 4387 | |
Christian Brauner | bd30336 | 2021-12-03 12:17:07 +0100 | [diff] [blame] | 4388 | /* |
Christian Brauner | 256c8ae | 2022-10-26 12:51:27 +0200 | [diff] [blame] | 4389 | * Pairs with smp_load_acquire() in mnt_idmap(). |
| 4390 | * |
| 4391 | * Since we only allow a mount to change the idmapping once and |
| 4392 | * verified this in can_idmap_mount() we know that the mount has |
| 4393 | * @nop_mnt_idmap attached to it. So there's no need to drop any |
| 4394 | * references. |
Christian Brauner | bd30336 | 2021-12-03 12:17:07 +0100 | [diff] [blame] | 4395 | */ |
Christian Brauner | 256c8ae | 2022-10-26 12:51:27 +0200 | [diff] [blame] | 4396 | smp_store_release(&mnt->mnt.mnt_idmap, mnt_idmap_get(kattr->mnt_idmap)); |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4397 | } |
| 4398 | |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4399 | static void mount_setattr_commit(struct mount_kattr *kattr, struct mount *mnt) |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4400 | { |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4401 | struct mount *m; |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4402 | |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4403 | for (m = mnt; m; m = next_mnt(m, mnt)) { |
| 4404 | unsigned int flags; |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4405 | |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4406 | do_idmap_mount(kattr, m); |
| 4407 | flags = recalc_flags(kattr, m); |
| 4408 | WRITE_ONCE(m->mnt.mnt_flags, flags); |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4409 | |
Christian Brauner | 03b6abe | 2022-02-03 14:14:09 +0100 | [diff] [blame] | 4410 | /* If we had to hold writers unblock them. */ |
| 4411 | if (m->mnt.mnt_flags & MNT_WRITE_HOLD) |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4412 | mnt_unhold_writers(m); |
| 4413 | |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4414 | if (kattr->propagation) |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4415 | change_mnt_propagation(m, kattr->propagation); |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4416 | if (!kattr->recurse) |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4417 | break; |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4418 | } |
| 4419 | touch_mnt_namespace(mnt->mnt_ns); |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4420 | } |
| 4421 | |
| 4422 | static int do_mount_setattr(struct path *path, struct mount_kattr *kattr) |
| 4423 | { |
Christian Brauner | 87bb5b6 | 2022-02-03 14:14:11 +0100 | [diff] [blame] | 4424 | struct mount *mnt = real_mount(path->mnt); |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4425 | int err = 0; |
| 4426 | |
Christian Brauner | 78aa08a | 2023-05-03 13:18:39 +0200 | [diff] [blame] | 4427 | if (!path_mounted(path)) |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4428 | return -EINVAL; |
| 4429 | |
Christian Brauner | 256c8ae | 2022-10-26 12:51:27 +0200 | [diff] [blame] | 4430 | if (kattr->mnt_userns) { |
| 4431 | struct mnt_idmap *mnt_idmap; |
| 4432 | |
| 4433 | mnt_idmap = alloc_mnt_idmap(kattr->mnt_userns); |
| 4434 | if (IS_ERR(mnt_idmap)) |
| 4435 | return PTR_ERR(mnt_idmap); |
| 4436 | kattr->mnt_idmap = mnt_idmap; |
| 4437 | } |
| 4438 | |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4439 | if (kattr->propagation) { |
| 4440 | /* |
| 4441 | * Only take namespace_lock() if we're actually changing |
| 4442 | * propagation. |
| 4443 | */ |
| 4444 | namespace_lock(); |
| 4445 | if (kattr->propagation == MS_SHARED) { |
| 4446 | err = invent_group_ids(mnt, kattr->recurse); |
| 4447 | if (err) { |
| 4448 | namespace_unlock(); |
| 4449 | return err; |
| 4450 | } |
| 4451 | } |
| 4452 | } |
| 4453 | |
Christian Brauner | 87bb5b6 | 2022-02-03 14:14:11 +0100 | [diff] [blame] | 4454 | err = -EINVAL; |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4455 | lock_mount_hash(); |
| 4456 | |
Christian Brauner | 87bb5b6 | 2022-02-03 14:14:11 +0100 | [diff] [blame] | 4457 | /* Ensure that this isn't anything purely vfs internal. */ |
| 4458 | if (!is_mounted(&mnt->mnt)) |
| 4459 | goto out; |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4460 | |
Christian Brauner | 87bb5b6 | 2022-02-03 14:14:11 +0100 | [diff] [blame] | 4461 | /* |
| 4462 | * If this is an attached mount make sure it's located in the callers |
| 4463 | * mount namespace. If it's not don't let the caller interact with it. |
| 4464 | * If this is a detached mount make sure it has an anonymous mount |
| 4465 | * namespace attached to it, i.e. we've created it via OPEN_TREE_CLONE. |
| 4466 | */ |
| 4467 | if (!(mnt_has_parent(mnt) ? check_mnt(mnt) : is_anon_ns(mnt->mnt_ns))) |
| 4468 | goto out; |
| 4469 | |
| 4470 | /* |
| 4471 | * First, we get the mount tree in a shape where we can change mount |
| 4472 | * properties without failure. If we succeeded to do so we commit all |
| 4473 | * changes and if we failed we clean up. |
| 4474 | */ |
| 4475 | err = mount_setattr_prepare(kattr, mnt); |
Al Viro | e257039 | 2022-02-28 23:04:20 -0500 | [diff] [blame] | 4476 | if (!err) |
| 4477 | mount_setattr_commit(kattr, mnt); |
Christian Brauner | 87bb5b6 | 2022-02-03 14:14:11 +0100 | [diff] [blame] | 4478 | |
| 4479 | out: |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4480 | unlock_mount_hash(); |
| 4481 | |
| 4482 | if (kattr->propagation) { |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4483 | if (err) |
| 4484 | cleanup_group_ids(mnt, NULL); |
Christian Brauner | cb2239c | 2023-03-30 09:13:16 +0200 | [diff] [blame] | 4485 | namespace_unlock(); |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4486 | } |
| 4487 | |
| 4488 | return err; |
| 4489 | } |
| 4490 | |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4491 | static int build_mount_idmapped(const struct mount_attr *attr, size_t usize, |
| 4492 | struct mount_kattr *kattr, unsigned int flags) |
| 4493 | { |
| 4494 | int err = 0; |
| 4495 | struct ns_common *ns; |
| 4496 | struct user_namespace *mnt_userns; |
Al Viro | 96e85e9 | 2022-06-06 00:30:50 -0400 | [diff] [blame] | 4497 | struct fd f; |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4498 | |
| 4499 | if (!((attr->attr_set | attr->attr_clr) & MOUNT_ATTR_IDMAP)) |
| 4500 | return 0; |
| 4501 | |
| 4502 | /* |
| 4503 | * We currently do not support clearing an idmapped mount. If this ever |
| 4504 | * is a use-case we can revisit this but for now let's keep it simple |
| 4505 | * and not allow it. |
| 4506 | */ |
| 4507 | if (attr->attr_clr & MOUNT_ATTR_IDMAP) |
| 4508 | return -EINVAL; |
| 4509 | |
| 4510 | if (attr->userns_fd > INT_MAX) |
| 4511 | return -EINVAL; |
| 4512 | |
Al Viro | 96e85e9 | 2022-06-06 00:30:50 -0400 | [diff] [blame] | 4513 | f = fdget(attr->userns_fd); |
| 4514 | if (!f.file) |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4515 | return -EBADF; |
| 4516 | |
Al Viro | 96e85e9 | 2022-06-06 00:30:50 -0400 | [diff] [blame] | 4517 | if (!proc_ns_file(f.file)) { |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4518 | err = -EINVAL; |
| 4519 | goto out_fput; |
| 4520 | } |
| 4521 | |
Al Viro | 96e85e9 | 2022-06-06 00:30:50 -0400 | [diff] [blame] | 4522 | ns = get_proc_ns(file_inode(f.file)); |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4523 | if (ns->ops->type != CLONE_NEWUSER) { |
| 4524 | err = -EINVAL; |
| 4525 | goto out_fput; |
| 4526 | } |
| 4527 | |
| 4528 | /* |
Christian Brauner | bd30336 | 2021-12-03 12:17:07 +0100 | [diff] [blame] | 4529 | * The initial idmapping cannot be used to create an idmapped |
| 4530 | * mount. We use the initial idmapping as an indicator of a mount |
| 4531 | * that is not idmapped. It can simply be passed into helpers that |
| 4532 | * are aware of idmapped mounts as a convenient shortcut. A user |
| 4533 | * can just create a dedicated identity mapping to achieve the same |
| 4534 | * result. |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4535 | */ |
| 4536 | mnt_userns = container_of(ns, struct user_namespace, ns); |
Christian Brauner | 3707d84 | 2023-01-13 12:49:33 +0100 | [diff] [blame] | 4537 | if (mnt_userns == &init_user_ns) { |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4538 | err = -EPERM; |
| 4539 | goto out_fput; |
| 4540 | } |
Seth Forshee | bf1ac16 | 2022-08-16 11:47:52 -0500 | [diff] [blame] | 4541 | |
| 4542 | /* We're not controlling the target namespace. */ |
| 4543 | if (!ns_capable(mnt_userns, CAP_SYS_ADMIN)) { |
| 4544 | err = -EPERM; |
| 4545 | goto out_fput; |
| 4546 | } |
| 4547 | |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4548 | kattr->mnt_userns = get_user_ns(mnt_userns); |
| 4549 | |
| 4550 | out_fput: |
Al Viro | 96e85e9 | 2022-06-06 00:30:50 -0400 | [diff] [blame] | 4551 | fdput(f); |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4552 | return err; |
| 4553 | } |
| 4554 | |
| 4555 | static int build_mount_kattr(const struct mount_attr *attr, size_t usize, |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4556 | struct mount_kattr *kattr, unsigned int flags) |
| 4557 | { |
| 4558 | unsigned int lookup_flags = LOOKUP_AUTOMOUNT | LOOKUP_FOLLOW; |
| 4559 | |
| 4560 | if (flags & AT_NO_AUTOMOUNT) |
| 4561 | lookup_flags &= ~LOOKUP_AUTOMOUNT; |
| 4562 | if (flags & AT_SYMLINK_NOFOLLOW) |
| 4563 | lookup_flags &= ~LOOKUP_FOLLOW; |
| 4564 | if (flags & AT_EMPTY_PATH) |
| 4565 | lookup_flags |= LOOKUP_EMPTY; |
| 4566 | |
| 4567 | *kattr = (struct mount_kattr) { |
| 4568 | .lookup_flags = lookup_flags, |
| 4569 | .recurse = !!(flags & AT_RECURSIVE), |
| 4570 | }; |
| 4571 | |
| 4572 | if (attr->propagation & ~MOUNT_SETATTR_PROPAGATION_FLAGS) |
| 4573 | return -EINVAL; |
| 4574 | if (hweight32(attr->propagation & MOUNT_SETATTR_PROPAGATION_FLAGS) > 1) |
| 4575 | return -EINVAL; |
| 4576 | kattr->propagation = attr->propagation; |
| 4577 | |
| 4578 | if ((attr->attr_set | attr->attr_clr) & ~MOUNT_SETATTR_VALID_FLAGS) |
| 4579 | return -EINVAL; |
| 4580 | |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4581 | kattr->attr_set = attr_flags_to_mnt_flags(attr->attr_set); |
| 4582 | kattr->attr_clr = attr_flags_to_mnt_flags(attr->attr_clr); |
| 4583 | |
| 4584 | /* |
| 4585 | * Since the MOUNT_ATTR_<atime> values are an enum, not a bitmap, |
| 4586 | * users wanting to transition to a different atime setting cannot |
| 4587 | * simply specify the atime setting in @attr_set, but must also |
| 4588 | * specify MOUNT_ATTR__ATIME in the @attr_clr field. |
| 4589 | * So ensure that MOUNT_ATTR__ATIME can't be partially set in |
| 4590 | * @attr_clr and that @attr_set can't have any atime bits set if |
| 4591 | * MOUNT_ATTR__ATIME isn't set in @attr_clr. |
| 4592 | */ |
| 4593 | if (attr->attr_clr & MOUNT_ATTR__ATIME) { |
| 4594 | if ((attr->attr_clr & MOUNT_ATTR__ATIME) != MOUNT_ATTR__ATIME) |
| 4595 | return -EINVAL; |
| 4596 | |
| 4597 | /* |
| 4598 | * Clear all previous time settings as they are mutually |
| 4599 | * exclusive. |
| 4600 | */ |
| 4601 | kattr->attr_clr |= MNT_RELATIME | MNT_NOATIME; |
| 4602 | switch (attr->attr_set & MOUNT_ATTR__ATIME) { |
| 4603 | case MOUNT_ATTR_RELATIME: |
| 4604 | kattr->attr_set |= MNT_RELATIME; |
| 4605 | break; |
| 4606 | case MOUNT_ATTR_NOATIME: |
| 4607 | kattr->attr_set |= MNT_NOATIME; |
| 4608 | break; |
| 4609 | case MOUNT_ATTR_STRICTATIME: |
| 4610 | break; |
| 4611 | default: |
| 4612 | return -EINVAL; |
| 4613 | } |
| 4614 | } else { |
| 4615 | if (attr->attr_set & MOUNT_ATTR__ATIME) |
| 4616 | return -EINVAL; |
| 4617 | } |
| 4618 | |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4619 | return build_mount_idmapped(attr, usize, kattr, flags); |
| 4620 | } |
| 4621 | |
| 4622 | static void finish_mount_kattr(struct mount_kattr *kattr) |
| 4623 | { |
| 4624 | put_user_ns(kattr->mnt_userns); |
| 4625 | kattr->mnt_userns = NULL; |
Christian Brauner | 256c8ae | 2022-10-26 12:51:27 +0200 | [diff] [blame] | 4626 | |
| 4627 | if (kattr->mnt_idmap) |
| 4628 | mnt_idmap_put(kattr->mnt_idmap); |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4629 | } |
| 4630 | |
| 4631 | SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path, |
| 4632 | unsigned int, flags, struct mount_attr __user *, uattr, |
| 4633 | size_t, usize) |
| 4634 | { |
| 4635 | int err; |
| 4636 | struct path target; |
| 4637 | struct mount_attr attr; |
| 4638 | struct mount_kattr kattr; |
| 4639 | |
| 4640 | BUILD_BUG_ON(sizeof(struct mount_attr) != MOUNT_ATTR_SIZE_VER0); |
| 4641 | |
| 4642 | if (flags & ~(AT_EMPTY_PATH | |
| 4643 | AT_RECURSIVE | |
| 4644 | AT_SYMLINK_NOFOLLOW | |
| 4645 | AT_NO_AUTOMOUNT)) |
| 4646 | return -EINVAL; |
| 4647 | |
| 4648 | if (unlikely(usize > PAGE_SIZE)) |
| 4649 | return -E2BIG; |
| 4650 | if (unlikely(usize < MOUNT_ATTR_SIZE_VER0)) |
| 4651 | return -EINVAL; |
| 4652 | |
| 4653 | if (!may_mount()) |
| 4654 | return -EPERM; |
| 4655 | |
| 4656 | err = copy_struct_from_user(&attr, sizeof(attr), uattr, usize); |
| 4657 | if (err) |
| 4658 | return err; |
| 4659 | |
| 4660 | /* Don't bother walking through the mounts if this is a nop. */ |
| 4661 | if (attr.attr_set == 0 && |
| 4662 | attr.attr_clr == 0 && |
| 4663 | attr.propagation == 0) |
| 4664 | return 0; |
| 4665 | |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4666 | err = build_mount_kattr(&attr, usize, &kattr, flags); |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4667 | if (err) |
| 4668 | return err; |
| 4669 | |
| 4670 | err = user_path_at(dfd, path, kattr.lookup_flags, &target); |
Christian Brauner | 012e332 | 2021-12-30 20:23:09 +0100 | [diff] [blame] | 4671 | if (!err) { |
| 4672 | err = do_mount_setattr(&target, &kattr); |
| 4673 | path_put(&target); |
| 4674 | } |
Christian Brauner | 9caccd4 | 2021-01-21 14:19:54 +0100 | [diff] [blame] | 4675 | finish_mount_kattr(&kattr); |
Christian Brauner | 2a18672 | 2021-01-21 14:19:53 +0100 | [diff] [blame] | 4676 | return err; |
| 4677 | } |
| 4678 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4679 | static void __init init_mount_tree(void) |
| 4680 | { |
| 4681 | struct vfsmount *mnt; |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 4682 | struct mount *m; |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 4683 | struct mnt_namespace *ns; |
Jan Blunck | ac748a0 | 2008-02-14 19:34:39 -0800 | [diff] [blame] | 4684 | struct path root; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4685 | |
Al Viro | fd3e007 | 2019-05-30 17:48:35 -0400 | [diff] [blame] | 4686 | mnt = vfs_kern_mount(&rootfs_fs_type, 0, "rootfs", NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4687 | if (IS_ERR(mnt)) |
| 4688 | panic("Can't create rootfs"); |
Nick Piggin | b3e19d9 | 2011-01-07 17:50:11 +1100 | [diff] [blame] | 4689 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 4690 | ns = alloc_mnt_ns(&init_user_ns, false); |
Trond Myklebust | 3b22edc | 2009-06-23 17:29:49 -0400 | [diff] [blame] | 4691 | if (IS_ERR(ns)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4692 | panic("Can't allocate initial namespace"); |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 4693 | m = real_mount(mnt); |
| 4694 | m->mnt_ns = ns; |
| 4695 | ns->root = m; |
| 4696 | ns->mounts = 1; |
| 4697 | list_add(&m->mnt_list, &ns->list); |
Kirill Korotaev | 6b3286e | 2006-12-08 02:37:56 -0800 | [diff] [blame] | 4698 | init_task.nsproxy->mnt_ns = ns; |
| 4699 | get_mnt_ns(ns); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4700 | |
Al Viro | be08d6d | 2011-12-06 13:32:36 -0500 | [diff] [blame] | 4701 | root.mnt = mnt; |
| 4702 | root.dentry = mnt->mnt_root; |
Eric W. Biederman | da362b0 | 2014-10-07 12:19:53 -0700 | [diff] [blame] | 4703 | mnt->mnt_flags |= MNT_LOCKED; |
Jan Blunck | ac748a0 | 2008-02-14 19:34:39 -0800 | [diff] [blame] | 4704 | |
| 4705 | set_fs_pwd(current->fs, &root); |
| 4706 | set_fs_root(current->fs, &root); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4707 | } |
| 4708 | |
Denis Cheng | 74bf17c | 2007-10-16 23:26:30 -0700 | [diff] [blame] | 4709 | void __init mnt_init(void) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4710 | { |
Randy Dunlap | 15a67dd | 2006-09-29 01:58:57 -0700 | [diff] [blame] | 4711 | int err; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4712 | |
Al Viro | 7d6fec4 | 2011-11-23 12:14:10 -0500 | [diff] [blame] | 4713 | mnt_cache = kmem_cache_create("mnt_cache", sizeof(struct mount), |
Vasily Averin | 79f6540 | 2021-09-02 14:55:10 -0700 | [diff] [blame] | 4714 | 0, SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4715 | |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 4716 | mount_hashtable = alloc_large_system_hash("Mount-cache", |
Al Viro | 38129a1 | 2014-03-20 21:10:51 -0400 | [diff] [blame] | 4717 | sizeof(struct hlist_head), |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 4718 | mhash_entries, 19, |
Pavel Tatashin | 3d375d7 | 2017-07-06 15:39:11 -0700 | [diff] [blame] | 4719 | HASH_ZERO, |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 4720 | &m_hash_shift, &m_hash_mask, 0, 0); |
| 4721 | mountpoint_hashtable = alloc_large_system_hash("Mountpoint-cache", |
| 4722 | sizeof(struct hlist_head), |
| 4723 | mphash_entries, 19, |
Pavel Tatashin | 3d375d7 | 2017-07-06 15:39:11 -0700 | [diff] [blame] | 4724 | HASH_ZERO, |
Al Viro | 0818bf2 | 2014-02-28 13:46:44 -0500 | [diff] [blame] | 4725 | &mp_hash_shift, &mp_hash_mask, 0, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4726 | |
Al Viro | 84d17192 | 2013-03-15 10:53:28 -0400 | [diff] [blame] | 4727 | if (!mount_hashtable || !mountpoint_hashtable) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4728 | panic("Failed to allocate mount hash table\n"); |
| 4729 | |
Tejun Heo | 4b93dc9 | 2013-11-28 14:54:43 -0500 | [diff] [blame] | 4730 | kernfs_init(); |
| 4731 | |
Randy Dunlap | 15a67dd | 2006-09-29 01:58:57 -0700 | [diff] [blame] | 4732 | err = sysfs_init(); |
| 4733 | if (err) |
| 4734 | printk(KERN_WARNING "%s: sysfs_init error: %d\n", |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 4735 | __func__, err); |
Greg Kroah-Hartman | 00d2666 | 2007-10-29 14:17:23 -0600 | [diff] [blame] | 4736 | fs_kobj = kobject_create_and_add("fs", NULL); |
| 4737 | if (!fs_kobj) |
Harvey Harrison | 8e24eea | 2008-04-30 00:55:09 -0700 | [diff] [blame] | 4738 | printk(KERN_WARNING "%s: kobj create error\n", __func__); |
Al Viro | 037f11b | 2019-06-01 18:09:44 -0400 | [diff] [blame] | 4739 | shmem_init(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4740 | init_rootfs(); |
| 4741 | init_mount_tree(); |
| 4742 | } |
| 4743 | |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 4744 | void put_mnt_ns(struct mnt_namespace *ns) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4745 | { |
Kirill Tkhai | 1a7b8969 | 2020-08-03 13:16:42 +0300 | [diff] [blame] | 4746 | if (!refcount_dec_and_test(&ns->ns.count)) |
Trond Myklebust | 616511d | 2009-06-22 15:09:13 -0400 | [diff] [blame] | 4747 | return; |
Al Viro | 7b00ed6 | 2013-09-16 21:19:20 -0400 | [diff] [blame] | 4748 | drop_collected_mounts(&ns->root->mnt); |
Eric W. Biederman | 771b137 | 2012-07-26 21:08:32 -0700 | [diff] [blame] | 4749 | free_mnt_ns(ns); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4750 | } |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 4751 | |
David Howells | d911b45 | 2018-11-01 23:07:26 +0000 | [diff] [blame] | 4752 | struct vfsmount *kern_mount(struct file_system_type *type) |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 4753 | { |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 4754 | struct vfsmount *mnt; |
David Howells | d911b45 | 2018-11-01 23:07:26 +0000 | [diff] [blame] | 4755 | mnt = vfs_kern_mount(type, SB_KERNMOUNT, type->name, NULL); |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 4756 | if (!IS_ERR(mnt)) { |
| 4757 | /* |
| 4758 | * it is a longterm mount, don't release mnt until |
| 4759 | * we unmount before file sys is unregistered |
| 4760 | */ |
Al Viro | f7a99c5 | 2012-06-09 00:59:08 -0400 | [diff] [blame] | 4761 | real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL; |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 4762 | } |
| 4763 | return mnt; |
Al Viro | 9d412a4 | 2011-03-17 22:08:28 -0400 | [diff] [blame] | 4764 | } |
David Howells | d911b45 | 2018-11-01 23:07:26 +0000 | [diff] [blame] | 4765 | EXPORT_SYMBOL_GPL(kern_mount); |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 4766 | |
| 4767 | void kern_unmount(struct vfsmount *mnt) |
| 4768 | { |
| 4769 | /* release long term mount so mount point can be released */ |
Rik van Riel | da27f79 | 2023-01-27 13:46:51 -0500 | [diff] [blame] | 4770 | if (!IS_ERR(mnt)) { |
| 4771 | mnt_make_shortterm(mnt); |
Al Viro | 48a066e | 2013-09-29 22:06:07 -0400 | [diff] [blame] | 4772 | synchronize_rcu(); /* yecchhh... */ |
Tim Chen | 423e0ab | 2011-07-19 09:32:38 -0700 | [diff] [blame] | 4773 | mntput(mnt); |
| 4774 | } |
| 4775 | } |
| 4776 | EXPORT_SYMBOL(kern_unmount); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 4777 | |
Miklos Szeredi | df820f8 | 2020-06-04 10:48:19 +0200 | [diff] [blame] | 4778 | void kern_unmount_array(struct vfsmount *mnt[], unsigned int num) |
| 4779 | { |
| 4780 | unsigned int i; |
| 4781 | |
| 4782 | for (i = 0; i < num; i++) |
Rik van Riel | da27f79 | 2023-01-27 13:46:51 -0500 | [diff] [blame] | 4783 | mnt_make_shortterm(mnt[i]); |
Miklos Szeredi | df820f8 | 2020-06-04 10:48:19 +0200 | [diff] [blame] | 4784 | synchronize_rcu_expedited(); |
| 4785 | for (i = 0; i < num; i++) |
| 4786 | mntput(mnt[i]); |
| 4787 | } |
| 4788 | EXPORT_SYMBOL(kern_unmount_array); |
| 4789 | |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 4790 | bool our_mnt(struct vfsmount *mnt) |
| 4791 | { |
Al Viro | 143c8c9 | 2011-11-25 00:46:35 -0500 | [diff] [blame] | 4792 | return check_mnt(real_mount(mnt)); |
Al Viro | 02125a8 | 2011-12-05 08:43:34 -0500 | [diff] [blame] | 4793 | } |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4794 | |
Eric W. Biederman | 3151527 | 2013-03-15 01:45:51 -0700 | [diff] [blame] | 4795 | bool current_chrooted(void) |
| 4796 | { |
| 4797 | /* Does the current process have a non-standard root */ |
| 4798 | struct path ns_root; |
| 4799 | struct path fs_root; |
| 4800 | bool chrooted; |
| 4801 | |
| 4802 | /* Find the namespace root */ |
| 4803 | ns_root.mnt = ¤t->nsproxy->mnt_ns->root->mnt; |
| 4804 | ns_root.dentry = ns_root.mnt->mnt_root; |
| 4805 | path_get(&ns_root); |
| 4806 | while (d_mountpoint(ns_root.dentry) && follow_down_one(&ns_root)) |
| 4807 | ; |
| 4808 | |
| 4809 | get_fs_root(current->fs, &fs_root); |
| 4810 | |
| 4811 | chrooted = !path_equal(&fs_root, &ns_root); |
| 4812 | |
| 4813 | path_put(&fs_root); |
| 4814 | path_put(&ns_root); |
| 4815 | |
| 4816 | return chrooted; |
| 4817 | } |
| 4818 | |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 4819 | static bool mnt_already_visible(struct mnt_namespace *ns, |
| 4820 | const struct super_block *sb, |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 4821 | int *new_mnt_flags) |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 4822 | { |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 4823 | int new_flags = *new_mnt_flags; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 4824 | struct mount *mnt; |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 4825 | bool visible = false; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 4826 | |
Al Viro | 44bb438 | 2013-09-16 21:37:36 -0400 | [diff] [blame] | 4827 | down_read(&namespace_sem); |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 4828 | lock_ns_list(ns); |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 4829 | list_for_each_entry(mnt, &ns->list, mnt_list) { |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 4830 | struct mount *child; |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 4831 | int mnt_flags; |
| 4832 | |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 4833 | if (mnt_is_cursor(mnt)) |
| 4834 | continue; |
| 4835 | |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 4836 | if (mnt->mnt.mnt_sb->s_type != sb->s_type) |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 4837 | continue; |
| 4838 | |
Eric W. Biederman | 7e96c1b | 2015-05-08 16:36:50 -0500 | [diff] [blame] | 4839 | /* This mount is not fully visible if it's root directory |
| 4840 | * is not the root directory of the filesystem. |
| 4841 | */ |
| 4842 | if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root) |
| 4843 | continue; |
| 4844 | |
Eric W. Biederman | a1935c1 | 2016-06-15 06:59:49 -0500 | [diff] [blame] | 4845 | /* A local view of the mount flags */ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 4846 | mnt_flags = mnt->mnt.mnt_flags; |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 4847 | |
Eric W. Biederman | 695e9df | 2016-06-10 12:21:40 -0500 | [diff] [blame] | 4848 | /* Don't miss readonly hidden in the superblock flags */ |
David Howells | bc98a42 | 2017-07-17 08:45:34 +0100 | [diff] [blame] | 4849 | if (sb_rdonly(mnt->mnt.mnt_sb)) |
Eric W. Biederman | 695e9df | 2016-06-10 12:21:40 -0500 | [diff] [blame] | 4850 | mnt_flags |= MNT_LOCK_READONLY; |
| 4851 | |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 4852 | /* Verify the mount flags are equal to or more permissive |
| 4853 | * than the proposed new mount. |
| 4854 | */ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 4855 | if ((mnt_flags & MNT_LOCK_READONLY) && |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 4856 | !(new_flags & MNT_READONLY)) |
| 4857 | continue; |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 4858 | if ((mnt_flags & MNT_LOCK_ATIME) && |
| 4859 | ((mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK))) |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 4860 | continue; |
| 4861 | |
Eric W. Biederman | ceeb0e5 | 2015-01-07 08:10:09 -0600 | [diff] [blame] | 4862 | /* This mount is not fully visible if there are any |
| 4863 | * locked child mounts that cover anything except for |
| 4864 | * empty directories. |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 4865 | */ |
| 4866 | list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { |
| 4867 | struct inode *inode = child->mnt_mountpoint->d_inode; |
Eric W. Biederman | ceeb0e5 | 2015-01-07 08:10:09 -0600 | [diff] [blame] | 4868 | /* Only worry about locked mounts */ |
Eric W. Biederman | d71ed6c | 2016-05-27 14:50:05 -0500 | [diff] [blame] | 4869 | if (!(child->mnt.mnt_flags & MNT_LOCKED)) |
Eric W. Biederman | ceeb0e5 | 2015-01-07 08:10:09 -0600 | [diff] [blame] | 4870 | continue; |
Eric W. Biederman | 7236c85 | 2015-05-13 20:51:09 -0500 | [diff] [blame] | 4871 | /* Is the directory permanetly empty? */ |
| 4872 | if (!is_empty_dir_inode(inode)) |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 4873 | goto next; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 4874 | } |
Eric W. Biederman | 8c6cf9c | 2015-05-08 23:49:47 -0500 | [diff] [blame] | 4875 | /* Preserve the locked attributes */ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 4876 | *new_mnt_flags |= mnt_flags & (MNT_LOCK_READONLY | \ |
Eric W. Biederman | 77b1a97 | 2015-06-04 09:43:11 -0500 | [diff] [blame] | 4877 | MNT_LOCK_ATIME); |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 4878 | visible = true; |
| 4879 | goto found; |
| 4880 | next: ; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 4881 | } |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 4882 | found: |
Miklos Szeredi | 9f6c61f | 2020-05-14 16:44:24 +0200 | [diff] [blame] | 4883 | unlock_ns_list(ns); |
Al Viro | 44bb438 | 2013-09-16 21:37:36 -0400 | [diff] [blame] | 4884 | up_read(&namespace_sem); |
Eric W. Biederman | e51db73 | 2013-03-30 19:57:41 -0700 | [diff] [blame] | 4885 | return visible; |
Eric W. Biederman | 87a8ebd | 2013-03-24 14:28:27 -0700 | [diff] [blame] | 4886 | } |
| 4887 | |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 4888 | static bool mount_too_revealing(const struct super_block *sb, int *new_mnt_flags) |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 4889 | { |
Eric W. Biederman | a1935c1 | 2016-06-15 06:59:49 -0500 | [diff] [blame] | 4890 | const unsigned long required_iflags = SB_I_NOEXEC | SB_I_NODEV; |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 4891 | struct mnt_namespace *ns = current->nsproxy->mnt_ns; |
| 4892 | unsigned long s_iflags; |
| 4893 | |
| 4894 | if (ns->user_ns == &init_user_ns) |
| 4895 | return false; |
| 4896 | |
| 4897 | /* Can this filesystem be too revealing? */ |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 4898 | s_iflags = sb->s_iflags; |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 4899 | if (!(s_iflags & SB_I_USERNS_VISIBLE)) |
| 4900 | return false; |
| 4901 | |
Eric W. Biederman | a1935c1 | 2016-06-15 06:59:49 -0500 | [diff] [blame] | 4902 | if ((s_iflags & required_iflags) != required_iflags) { |
| 4903 | WARN_ONCE(1, "Expected s_iflags to contain 0x%lx\n", |
| 4904 | required_iflags); |
| 4905 | return true; |
| 4906 | } |
| 4907 | |
David Howells | 132e460 | 2018-11-04 07:43:08 -0500 | [diff] [blame] | 4908 | return !mnt_already_visible(ns, sb, new_mnt_flags); |
Eric W. Biederman | 8654df4 | 2016-06-09 16:06:06 -0500 | [diff] [blame] | 4909 | } |
| 4910 | |
Andy Lutomirski | 380cf5b | 2016-06-23 16:41:05 -0500 | [diff] [blame] | 4911 | bool mnt_may_suid(struct vfsmount *mnt) |
| 4912 | { |
| 4913 | /* |
| 4914 | * Foreign mounts (accessed via fchdir or through /proc |
| 4915 | * symlinks) are always treated as if they are nosuid. This |
| 4916 | * prevents namespaces from trusting potentially unsafe |
| 4917 | * suid/sgid bits, file caps, or security labels that originate |
| 4918 | * in other namespaces. |
| 4919 | */ |
| 4920 | return !(mnt->mnt_flags & MNT_NOSUID) && check_mnt(real_mount(mnt)) && |
| 4921 | current_in_userns(mnt->mnt_sb->s_user_ns); |
| 4922 | } |
| 4923 | |
Al Viro | 6496452 | 2014-11-01 00:37:32 -0400 | [diff] [blame] | 4924 | static struct ns_common *mntns_get(struct task_struct *task) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4925 | { |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 4926 | struct ns_common *ns = NULL; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4927 | struct nsproxy *nsproxy; |
| 4928 | |
Eric W. Biederman | 728dba3 | 2014-02-03 19:13:49 -0800 | [diff] [blame] | 4929 | task_lock(task); |
| 4930 | nsproxy = task->nsproxy; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4931 | if (nsproxy) { |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 4932 | ns = &nsproxy->mnt_ns->ns; |
| 4933 | get_mnt_ns(to_mnt_ns(ns)); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4934 | } |
Eric W. Biederman | 728dba3 | 2014-02-03 19:13:49 -0800 | [diff] [blame] | 4935 | task_unlock(task); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4936 | |
| 4937 | return ns; |
| 4938 | } |
| 4939 | |
Al Viro | 6496452 | 2014-11-01 00:37:32 -0400 | [diff] [blame] | 4940 | static void mntns_put(struct ns_common *ns) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4941 | { |
Al Viro | 58be2825 | 2014-11-01 00:00:23 -0400 | [diff] [blame] | 4942 | put_mnt_ns(to_mnt_ns(ns)); |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4943 | } |
| 4944 | |
Christian Brauner | f2a8d52 | 2020-05-05 16:04:30 +0200 | [diff] [blame] | 4945 | static int mntns_install(struct nsset *nsset, struct ns_common *ns) |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4946 | { |
Christian Brauner | f2a8d52 | 2020-05-05 16:04:30 +0200 | [diff] [blame] | 4947 | struct nsproxy *nsproxy = nsset->nsproxy; |
| 4948 | struct fs_struct *fs = nsset->fs; |
Al Viro | 4f757f3 | 2017-04-15 17:31:22 -0400 | [diff] [blame] | 4949 | struct mnt_namespace *mnt_ns = to_mnt_ns(ns), *old_mnt_ns; |
Christian Brauner | f2a8d52 | 2020-05-05 16:04:30 +0200 | [diff] [blame] | 4950 | struct user_namespace *user_ns = nsset->cred->user_ns; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4951 | struct path root; |
Al Viro | 4f757f3 | 2017-04-15 17:31:22 -0400 | [diff] [blame] | 4952 | int err; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4953 | |
Eric W. Biederman | 0c55cfc | 2012-07-26 21:42:03 -0700 | [diff] [blame] | 4954 | if (!ns_capable(mnt_ns->user_ns, CAP_SYS_ADMIN) || |
Christian Brauner | f2a8d52 | 2020-05-05 16:04:30 +0200 | [diff] [blame] | 4955 | !ns_capable(user_ns, CAP_SYS_CHROOT) || |
| 4956 | !ns_capable(user_ns, CAP_SYS_ADMIN)) |
Zhao Hongjiang | ae11e0f | 2012-09-13 16:38:03 +0800 | [diff] [blame] | 4957 | return -EPERM; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4958 | |
Al Viro | 74e8312 | 2019-01-30 13:30:21 -0500 | [diff] [blame] | 4959 | if (is_anon_ns(mnt_ns)) |
| 4960 | return -EINVAL; |
| 4961 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4962 | if (fs->users != 1) |
| 4963 | return -EINVAL; |
| 4964 | |
| 4965 | get_mnt_ns(mnt_ns); |
Al Viro | 4f757f3 | 2017-04-15 17:31:22 -0400 | [diff] [blame] | 4966 | old_mnt_ns = nsproxy->mnt_ns; |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4967 | nsproxy->mnt_ns = mnt_ns; |
| 4968 | |
| 4969 | /* Find the root */ |
Al Viro | 4f757f3 | 2017-04-15 17:31:22 -0400 | [diff] [blame] | 4970 | err = vfs_path_lookup(mnt_ns->root->mnt.mnt_root, &mnt_ns->root->mnt, |
| 4971 | "/", LOOKUP_DOWN, &root); |
| 4972 | if (err) { |
| 4973 | /* revert to old namespace */ |
| 4974 | nsproxy->mnt_ns = old_mnt_ns; |
| 4975 | put_mnt_ns(mnt_ns); |
| 4976 | return err; |
| 4977 | } |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4978 | |
Andrei Vagin | 4068367 | 2017-06-08 17:32:29 -0700 | [diff] [blame] | 4979 | put_mnt_ns(old_mnt_ns); |
| 4980 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4981 | /* Update the pwd and root */ |
| 4982 | set_fs_pwd(fs, &root); |
| 4983 | set_fs_root(fs, &root); |
| 4984 | |
| 4985 | path_put(&root); |
| 4986 | return 0; |
| 4987 | } |
| 4988 | |
Andrey Vagin | bcac25a | 2016-09-06 00:47:13 -0700 | [diff] [blame] | 4989 | static struct user_namespace *mntns_owner(struct ns_common *ns) |
| 4990 | { |
| 4991 | return to_mnt_ns(ns)->user_ns; |
| 4992 | } |
| 4993 | |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 4994 | const struct proc_ns_operations mntns_operations = { |
| 4995 | .name = "mnt", |
| 4996 | .type = CLONE_NEWNS, |
| 4997 | .get = mntns_get, |
| 4998 | .put = mntns_put, |
| 4999 | .install = mntns_install, |
Andrey Vagin | bcac25a | 2016-09-06 00:47:13 -0700 | [diff] [blame] | 5000 | .owner = mntns_owner, |
Eric W. Biederman | 8823c07 | 2010-03-07 18:49:36 -0800 | [diff] [blame] | 5001 | }; |
Luis Chamberlain | ab171b9 | 2022-01-21 22:13:27 -0800 | [diff] [blame] | 5002 | |
| 5003 | #ifdef CONFIG_SYSCTL |
| 5004 | static struct ctl_table fs_namespace_sysctls[] = { |
| 5005 | { |
| 5006 | .procname = "mount-max", |
| 5007 | .data = &sysctl_mount_max, |
| 5008 | .maxlen = sizeof(unsigned int), |
| 5009 | .mode = 0644, |
| 5010 | .proc_handler = proc_dointvec_minmax, |
| 5011 | .extra1 = SYSCTL_ONE, |
| 5012 | }, |
| 5013 | { } |
| 5014 | }; |
| 5015 | |
| 5016 | static int __init init_fs_namespace_sysctls(void) |
| 5017 | { |
| 5018 | register_sysctl_init("fs", fs_namespace_sysctls); |
| 5019 | return 0; |
| 5020 | } |
| 5021 | fs_initcall(init_fs_namespace_sysctls); |
| 5022 | |
| 5023 | #endif /* CONFIG_SYSCTL */ |