blob: 07e22a15ef02bb606e355765de0ff024131b2ef5 [file] [log] [blame]
Greg Kroah-Hartmanb2441312017-11-01 15:07:57 +01001// SPDX-License-Identifier: GPL-2.0
Al Viroe149ed22014-11-01 10:57:28 -04002#include <linux/mount.h>
David Howells059b20d2019-03-25 16:38:23 +00003#include <linux/pseudo_fs.h>
Al Viroe149ed22014-11-01 10:57:28 -04004#include <linux/file.h>
5#include <linux/fs.h>
Eric Biggers7bebd69e2020-01-04 12:59:52 -08006#include <linux/proc_fs.h>
Al Viroe149ed22014-11-01 10:57:28 -04007#include <linux/proc_ns.h>
8#include <linux/magic.h>
9#include <linux/ktime.h>
Eric W. Biederman75509fd2015-05-24 12:49:04 -050010#include <linux/seq_file.h>
Andrey Vagin67867412016-09-06 00:47:14 -070011#include <linux/user_namespace.h>
12#include <linux/nsfs.h>
Michael Kerrisk (man-pages)d95fa3c2017-01-25 14:04:15 +130013#include <linux/uaccess.h>
Al Viroe149ed22014-11-01 10:57:28 -040014
Eric Biggers7bebd69e2020-01-04 12:59:52 -080015#include "internal.h"
16
Al Viroe149ed22014-11-01 10:57:28 -040017static struct vfsmount *nsfs_mnt;
18
Andrey Vagin67867412016-09-06 00:47:14 -070019static long ns_ioctl(struct file *filp, unsigned int ioctl,
20 unsigned long arg);
Al Viroe149ed22014-11-01 10:57:28 -040021static const struct file_operations ns_file_operations = {
22 .llseek = no_llseek,
Andrey Vagin67867412016-09-06 00:47:14 -070023 .unlocked_ioctl = ns_ioctl,
Thomas Weißschuh1cb925c2023-01-11 16:46:30 +000024 .compat_ioctl = compat_ptr_ioctl,
Al Viroe149ed22014-11-01 10:57:28 -040025};
26
27static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
28{
David Howells75c3cfa2015-03-17 22:26:12 +000029 struct inode *inode = d_inode(dentry);
Christian Brauner1fa08ae2024-02-18 14:51:23 +010030 struct ns_common *ns = inode->i_private;
31 const struct proc_ns_operations *ns_ops = ns->ops;
Al Viroe149ed22014-11-01 10:57:28 -040032
Al Viro0f60d282022-01-30 15:03:49 -050033 return dynamic_dname(buffer, buflen, "%s:[%lu]",
Al Viroe149ed22014-11-01 10:57:28 -040034 ns_ops->name, inode->i_ino);
35}
36
Christian Brauner2558e3b2024-02-21 09:59:51 +010037const struct dentry_operations ns_dentry_operations = {
Al Viroe149ed22014-11-01 10:57:28 -040038 .d_delete = always_delete_dentry,
39 .d_dname = ns_dname,
Christian Brauner2558e3b2024-02-21 09:59:51 +010040 .d_prune = stashed_dentry_prune,
Al Viroe149ed22014-11-01 10:57:28 -040041};
42
43static void nsfs_evict(struct inode *inode)
44{
45 struct ns_common *ns = inode->i_private;
46 clear_inode(inode);
47 ns->ops->put(ns);
48}
49
Aleksa Saraice623f82019-12-07 01:13:27 +110050int ns_get_path_cb(struct path *path, ns_get_path_helper_t *ns_get_cb,
Jakub Kicinskicdab6ba2017-12-27 18:39:08 -080051 void *private_data)
Andrey Vagin67867412016-09-06 00:47:14 -070052{
Christian Brauner159a0d92024-02-18 14:52:24 +010053 struct ns_common *ns;
Andrey Vagin67867412016-09-06 00:47:14 -070054
Christian Brauner159a0d92024-02-18 14:52:24 +010055 ns = ns_get_cb(private_data);
56 if (!ns)
57 return -ENOENT;
Christian Braunere9c52632024-03-01 10:26:03 +010058
Christian Brauner9d9539d2024-03-12 10:39:44 +010059 return path_from_stashed(&ns->stashed, nsfs_mnt, ns, path);
Andrey Vagin67867412016-09-06 00:47:14 -070060}
61
Jakub Kicinskicdab6ba2017-12-27 18:39:08 -080062struct ns_get_path_task_args {
63 const struct proc_ns_operations *ns_ops;
64 struct task_struct *task;
65};
66
67static struct ns_common *ns_get_path_task(void *private_data)
68{
69 struct ns_get_path_task_args *args = private_data;
70
71 return args->ns_ops->get(args->task);
72}
73
Aleksa Saraice623f82019-12-07 01:13:27 +110074int ns_get_path(struct path *path, struct task_struct *task,
Jakub Kicinskicdab6ba2017-12-27 18:39:08 -080075 const struct proc_ns_operations *ns_ops)
76{
77 struct ns_get_path_task_args args = {
78 .ns_ops = ns_ops,
79 .task = task,
80 };
81
82 return ns_get_path_cb(path, ns_get_path_task, &args);
83}
84
Andrey Vaginc62cce22016-10-24 18:29:13 -070085int open_related_ns(struct ns_common *ns,
Andrey Vagin67867412016-09-06 00:47:14 -070086 struct ns_common *(*get_ns)(struct ns_common *ns))
87{
88 struct path path = {};
Christian Brauner159a0d92024-02-18 14:52:24 +010089 struct ns_common *relative;
Andrey Vagin67867412016-09-06 00:47:14 -070090 struct file *f;
Aleksa Saraice623f82019-12-07 01:13:27 +110091 int err;
Andrey Vagin67867412016-09-06 00:47:14 -070092 int fd;
93
94 fd = get_unused_fd_flags(O_CLOEXEC);
95 if (fd < 0)
96 return fd;
97
Christian Brauner159a0d92024-02-18 14:52:24 +010098 relative = get_ns(ns);
99 if (IS_ERR(relative)) {
100 put_unused_fd(fd);
101 return PTR_ERR(relative);
102 }
Andrey Vagin67867412016-09-06 00:47:14 -0700103
Christian Brauner9d9539d2024-03-12 10:39:44 +0100104 err = path_from_stashed(&relative->stashed, nsfs_mnt, relative, &path);
Christian Brauner1fa08ae2024-02-18 14:51:23 +0100105 if (err < 0) {
Andrey Vagin67867412016-09-06 00:47:14 -0700106 put_unused_fd(fd);
Aleksa Saraice623f82019-12-07 01:13:27 +1100107 return err;
Andrey Vagin67867412016-09-06 00:47:14 -0700108 }
109
110 f = dentry_open(&path, O_RDONLY, current_cred());
111 path_put(&path);
112 if (IS_ERR(f)) {
113 put_unused_fd(fd);
114 fd = PTR_ERR(f);
115 } else
116 fd_install(fd, f);
117
118 return fd;
119}
Kirill Tkhai24dce082018-02-14 16:40:05 +0300120EXPORT_SYMBOL_GPL(open_related_ns);
Andrey Vagin67867412016-09-06 00:47:14 -0700121
122static long ns_ioctl(struct file *filp, unsigned int ioctl,
123 unsigned long arg)
124{
Michael Kerrisk (man-pages)d95fa3c2017-01-25 14:04:15 +1300125 struct user_namespace *user_ns;
Andrey Vagin67867412016-09-06 00:47:14 -0700126 struct ns_common *ns = get_proc_ns(file_inode(filp));
Michael Kerrisk (man-pages)d95fa3c2017-01-25 14:04:15 +1300127 uid_t __user *argp;
128 uid_t uid;
Andrey Vagin67867412016-09-06 00:47:14 -0700129
130 switch (ioctl) {
131 case NS_GET_USERNS:
132 return open_related_ns(ns, ns_get_owner);
Andrey Vagina7306ed2016-09-06 00:47:15 -0700133 case NS_GET_PARENT:
134 if (!ns->ops->get_parent)
135 return -EINVAL;
136 return open_related_ns(ns, ns->ops->get_parent);
Michael Kerrisk (man-pages)e5ff5ce2017-01-25 14:03:36 +1300137 case NS_GET_NSTYPE:
138 return ns->ops->type;
Michael Kerrisk (man-pages)d95fa3c2017-01-25 14:04:15 +1300139 case NS_GET_OWNER_UID:
140 if (ns->ops->type != CLONE_NEWUSER)
141 return -EINVAL;
142 user_ns = container_of(ns, struct user_namespace, ns);
143 argp = (uid_t __user *) arg;
144 uid = from_kuid_munged(current_user_ns(), user_ns->owner);
145 return put_user(uid, argp);
Andrey Vagin67867412016-09-06 00:47:14 -0700146 default:
147 return -ENOTTY;
148 }
149}
150
Al Viroe149ed22014-11-01 10:57:28 -0400151int ns_get_name(char *buf, size_t size, struct task_struct *task,
152 const struct proc_ns_operations *ns_ops)
153{
154 struct ns_common *ns;
155 int res = -ENOENT;
Kirill Tkhai25b14e92017-05-08 15:56:38 -0700156 const char *name;
Al Viroe149ed22014-11-01 10:57:28 -0400157 ns = ns_ops->get(task);
158 if (ns) {
Kirill Tkhai25b14e92017-05-08 15:56:38 -0700159 name = ns_ops->real_ns_name ? : ns_ops->name;
160 res = snprintf(buf, size, "%s:[%u]", name, ns->inum);
Al Viroe149ed22014-11-01 10:57:28 -0400161 ns_ops->put(ns);
162 }
163 return res;
164}
165
Christian Brauner303cc572020-05-05 16:04:31 +0200166bool proc_ns_file(const struct file *file)
167{
168 return file->f_op == &ns_file_operations;
169}
170
Carlos Neira1e2328e2020-03-04 17:41:55 -0300171/**
172 * ns_match() - Returns true if current namespace matches dev/ino provided.
Lukas Bulwahn39ecb652022-11-07 12:08:17 +0100173 * @ns: current namespace
Carlos Neira1e2328e2020-03-04 17:41:55 -0300174 * @dev: dev_t from nsfs that will be matched against current nsfs
175 * @ino: ino_t from nsfs that will be matched against current nsfs
176 *
177 * Return: true if dev and ino matches the current nsfs.
178 */
179bool ns_match(const struct ns_common *ns, dev_t dev, ino_t ino)
180{
181 return (ns->inum == ino) && (nsfs_mnt->mnt_sb->s_dev == dev);
182}
183
184
Eric W. Biederman75509fd2015-05-24 12:49:04 -0500185static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
186{
187 struct inode *inode = d_inode(dentry);
Christian Brauner1fa08ae2024-02-18 14:51:23 +0100188 const struct ns_common *ns = inode->i_private;
189 const struct proc_ns_operations *ns_ops = ns->ops;
Eric W. Biederman75509fd2015-05-24 12:49:04 -0500190
Joe Perches6798a8c2015-09-11 13:07:48 -0700191 seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);
192 return 0;
Eric W. Biederman75509fd2015-05-24 12:49:04 -0500193}
194
Al Viroe149ed22014-11-01 10:57:28 -0400195static const struct super_operations nsfs_ops = {
196 .statfs = simple_statfs,
197 .evict_inode = nsfs_evict,
Eric W. Biederman75509fd2015-05-24 12:49:04 -0500198 .show_path = nsfs_show_path,
Al Viroe149ed22014-11-01 10:57:28 -0400199};
David Howells059b20d2019-03-25 16:38:23 +0000200
Christian Brauner9d9539d2024-03-12 10:39:44 +0100201static int nsfs_init_inode(struct inode *inode, void *data)
Christian Braunere9c52632024-03-01 10:26:03 +0100202{
Christian Brauner9d9539d2024-03-12 10:39:44 +0100203 struct ns_common *ns = data;
204
Christian Braunere9c52632024-03-01 10:26:03 +0100205 inode->i_private = data;
206 inode->i_mode |= S_IRUGO;
207 inode->i_fop = &ns_file_operations;
Christian Brauner9d9539d2024-03-12 10:39:44 +0100208 inode->i_ino = ns->inum;
209 return 0;
Christian Braunere9c52632024-03-01 10:26:03 +0100210}
211
212static void nsfs_put_data(void *data)
213{
214 struct ns_common *ns = data;
215 ns->ops->put(ns);
216}
217
218static const struct stashed_operations nsfs_stashed_ops = {
219 .init_inode = nsfs_init_inode,
220 .put_data = nsfs_put_data,
221};
222
David Howells059b20d2019-03-25 16:38:23 +0000223static int nsfs_init_fs_context(struct fs_context *fc)
Al Viroe149ed22014-11-01 10:57:28 -0400224{
David Howells059b20d2019-03-25 16:38:23 +0000225 struct pseudo_fs_context *ctx = init_pseudo(fc, NSFS_MAGIC);
226 if (!ctx)
227 return -ENOMEM;
228 ctx->ops = &nsfs_ops;
229 ctx->dops = &ns_dentry_operations;
Christian Braunere9c52632024-03-01 10:26:03 +0100230 fc->s_fs_info = (void *)&nsfs_stashed_ops;
David Howells059b20d2019-03-25 16:38:23 +0000231 return 0;
Al Viroe149ed22014-11-01 10:57:28 -0400232}
David Howells059b20d2019-03-25 16:38:23 +0000233
Al Viroe149ed22014-11-01 10:57:28 -0400234static struct file_system_type nsfs = {
235 .name = "nsfs",
David Howells059b20d2019-03-25 16:38:23 +0000236 .init_fs_context = nsfs_init_fs_context,
Al Viroe149ed22014-11-01 10:57:28 -0400237 .kill_sb = kill_anon_super,
238};
239
240void __init nsfs_init(void)
241{
242 nsfs_mnt = kern_mount(&nsfs);
243 if (IS_ERR(nsfs_mnt))
244 panic("can't set nsfs up\n");
Linus Torvalds1751e8a2017-11-27 13:05:09 -0800245 nsfs_mnt->mnt_sb->s_flags &= ~SB_NOUSER;
Al Viroe149ed22014-11-01 10:57:28 -0400246}