Greg Kroah-Hartman | b244131 | 2017-11-01 15:07:57 +0100 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | /* |
| 3 | * linux/fs/file.c |
| 4 | * |
| 5 | * Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes |
| 6 | * |
| 7 | * Manage the dynamic fd arrays in the process files_struct. |
| 8 | */ |
| 9 | |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 10 | #include <linux/syscalls.h> |
Paul Gortmaker | 630d9c4 | 2011-11-16 23:57:37 -0500 | [diff] [blame] | 11 | #include <linux/export.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 12 | #include <linux/fs.h> |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 13 | #include <linux/kernel.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 14 | #include <linux/mm.h> |
Ingo Molnar | 3f07c01 | 2017-02-08 18:51:30 +0100 | [diff] [blame] | 15 | #include <linux/sched/signal.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | #include <linux/slab.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 17 | #include <linux/file.h> |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 18 | #include <linux/fdtable.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 19 | #include <linux/bitops.h> |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 20 | #include <linux/spinlock.h> |
| 21 | #include <linux/rcupdate.h> |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 22 | #include <linux/close_range.h> |
Kees Cook | 6659061 | 2020-06-10 08:20:05 -0700 | [diff] [blame] | 23 | #include <net/sock.h> |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 24 | |
Jens Axboe | 53dec2e | 2021-01-19 15:41:52 -0700 | [diff] [blame] | 25 | #include "internal.h" |
| 26 | |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 27 | unsigned int sysctl_nr_open __read_mostly = 1024*1024; |
| 28 | unsigned int sysctl_nr_open_min = BITS_PER_LONG; |
Rasmus Villemoes | 752343b | 2015-10-29 12:01:41 +0100 | [diff] [blame] | 29 | /* our min() is unusable in constant expressions ;-/ */ |
| 30 | #define __const_min(x, y) ((x) < (y) ? (x) : (y)) |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 31 | unsigned int sysctl_nr_open_max = |
| 32 | __const_min(INT_MAX, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG; |
Eric Dumazet | 9cfe015 | 2008-02-06 01:37:16 -0800 | [diff] [blame] | 33 | |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 34 | static void __free_fdtable(struct fdtable *fdt) |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 35 | { |
Al Viro | f6c0a19 | 2014-04-23 10:18:46 -0400 | [diff] [blame] | 36 | kvfree(fdt->fd); |
| 37 | kvfree(fdt->open_fds); |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 38 | kfree(fdt); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 39 | } |
| 40 | |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 41 | static void free_fdtable_rcu(struct rcu_head *rcu) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 42 | { |
Al Viro | ac3e3c5 | 2013-04-28 21:42:33 -0400 | [diff] [blame] | 43 | __free_fdtable(container_of(rcu, struct fdtable, rcu)); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 44 | } |
| 45 | |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 46 | #define BITBIT_NR(nr) BITS_TO_LONGS(BITS_TO_LONGS(nr)) |
| 47 | #define BITBIT_SIZE(nr) (BITBIT_NR(nr) * sizeof(long)) |
| 48 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 49 | /* |
Eric Biggers | ea5c58e | 2015-11-06 00:32:04 -0600 | [diff] [blame] | 50 | * Copy 'count' fd bits from the old table to the new table and clear the extra |
| 51 | * space if any. This does not copy the file pointers. Called with the files |
| 52 | * spinlock held for write. |
| 53 | */ |
| 54 | static void copy_fd_bitmaps(struct fdtable *nfdt, struct fdtable *ofdt, |
| 55 | unsigned int count) |
| 56 | { |
| 57 | unsigned int cpy, set; |
| 58 | |
| 59 | cpy = count / BITS_PER_BYTE; |
| 60 | set = (nfdt->max_fds - count) / BITS_PER_BYTE; |
| 61 | memcpy(nfdt->open_fds, ofdt->open_fds, cpy); |
| 62 | memset((char *)nfdt->open_fds + cpy, 0, set); |
| 63 | memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy); |
| 64 | memset((char *)nfdt->close_on_exec + cpy, 0, set); |
| 65 | |
| 66 | cpy = BITBIT_SIZE(count); |
| 67 | set = BITBIT_SIZE(nfdt->max_fds) - cpy; |
| 68 | memcpy(nfdt->full_fds_bits, ofdt->full_fds_bits, cpy); |
| 69 | memset((char *)nfdt->full_fds_bits + cpy, 0, set); |
| 70 | } |
| 71 | |
| 72 | /* |
| 73 | * Copy all file descriptors from the old table to the new, expanded table and |
| 74 | * clear the extra space. Called with the files spinlock held for write. |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 75 | */ |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 76 | static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 77 | { |
Al Viro | 4e89b72 | 2020-05-19 17:48:52 -0400 | [diff] [blame] | 78 | size_t cpy, set; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 79 | |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 80 | BUG_ON(nfdt->max_fds < ofdt->max_fds); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 81 | |
| 82 | cpy = ofdt->max_fds * sizeof(struct file *); |
| 83 | set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *); |
| 84 | memcpy(nfdt->fd, ofdt->fd, cpy); |
Eric Biggers | ea5c58e | 2015-11-06 00:32:04 -0600 | [diff] [blame] | 85 | memset((char *)nfdt->fd + cpy, 0, set); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 86 | |
Eric Biggers | ea5c58e | 2015-11-06 00:32:04 -0600 | [diff] [blame] | 87 | copy_fd_bitmaps(nfdt, ofdt, ofdt->max_fds); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 88 | } |
| 89 | |
Linus Torvalds | 1c24a18 | 2022-03-29 15:06:39 -0700 | [diff] [blame] | 90 | /* |
| 91 | * Note how the fdtable bitmap allocations very much have to be a multiple of |
| 92 | * BITS_PER_LONG. This is not only because we walk those things in chunks of |
| 93 | * 'unsigned long' in some places, but simply because that is how the Linux |
| 94 | * kernel bitmaps are defined to work: they are not "bits in an array of bytes", |
| 95 | * they are very much "bits in an array of unsigned long". |
| 96 | * |
| 97 | * The ALIGN(nr, BITS_PER_LONG) here is for clarity: since we just multiplied |
| 98 | * by that "1024/sizeof(ptr)" before, we already know there are sufficient |
| 99 | * clear low bits. Clang seems to realize that, gcc ends up being confused. |
| 100 | * |
| 101 | * On a 128-bit machine, the ALIGN() would actually matter. In the meantime, |
| 102 | * let's consider it documentation (and maybe a test-case for gcc to improve |
| 103 | * its code generation ;) |
| 104 | */ |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 105 | static struct fdtable * alloc_fdtable(unsigned int nr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 106 | { |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 107 | struct fdtable *fdt; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 108 | void *data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 109 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 110 | /* |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 111 | * Figure out how many fds we actually want to support in this fdtable. |
| 112 | * Allocation steps are keyed to the size of the fdarray, since it |
| 113 | * grows far faster than any of the other dynamic data. We try to fit |
| 114 | * the fdarray into comfortable page-tuned chunks: starting at 1024B |
| 115 | * and growing in powers of two from there on. |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 116 | */ |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 117 | nr /= (1024 / sizeof(struct file *)); |
| 118 | nr = roundup_pow_of_two(nr + 1); |
| 119 | nr *= (1024 / sizeof(struct file *)); |
Linus Torvalds | 1c24a18 | 2022-03-29 15:06:39 -0700 | [diff] [blame] | 120 | nr = ALIGN(nr, BITS_PER_LONG); |
Al Viro | 5c598b3 | 2008-04-27 20:04:15 -0400 | [diff] [blame] | 121 | /* |
| 122 | * Note that this can drive nr *below* what we had passed if sysctl_nr_open |
| 123 | * had been set lower between the check in expand_files() and here. Deal |
| 124 | * with that in caller, it's cheaper that way. |
| 125 | * |
| 126 | * We make sure that nr remains a multiple of BITS_PER_LONG - otherwise |
| 127 | * bitmaps handling below becomes unpleasant, to put it mildly... |
| 128 | */ |
| 129 | if (unlikely(nr > sysctl_nr_open)) |
| 130 | nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1; |
Vadim Lobanov | bbea9f6 | 2006-12-10 02:21:12 -0800 | [diff] [blame] | 131 | |
Vladimir Davydov | 5d09705 | 2016-01-14 15:18:21 -0800 | [diff] [blame] | 132 | fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL_ACCOUNT); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 133 | if (!fdt) |
Vadim Lobanov | bbea9f6 | 2006-12-10 02:21:12 -0800 | [diff] [blame] | 134 | goto out; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 135 | fdt->max_fds = nr; |
Michal Hocko | c823bd9 | 2017-07-06 15:36:19 -0700 | [diff] [blame] | 136 | data = kvmalloc_array(nr, sizeof(struct file *), GFP_KERNEL_ACCOUNT); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 137 | if (!data) |
| 138 | goto out_fdt; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 139 | fdt->fd = data; |
| 140 | |
Michal Hocko | c823bd9 | 2017-07-06 15:36:19 -0700 | [diff] [blame] | 141 | data = kvmalloc(max_t(size_t, |
| 142 | 2 * nr / BITS_PER_BYTE + BITBIT_SIZE(nr), L1_CACHE_BYTES), |
| 143 | GFP_KERNEL_ACCOUNT); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 144 | if (!data) |
| 145 | goto out_arr; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 146 | fdt->open_fds = data; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 147 | data += nr / BITS_PER_BYTE; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 148 | fdt->close_on_exec = data; |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 149 | data += nr / BITS_PER_BYTE; |
| 150 | fdt->full_fds_bits = data; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 151 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 152 | return fdt; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 153 | |
| 154 | out_arr: |
Al Viro | f6c0a19 | 2014-04-23 10:18:46 -0400 | [diff] [blame] | 155 | kvfree(fdt->fd); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 156 | out_fdt: |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 157 | kfree(fdt); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 158 | out: |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 159 | return NULL; |
| 160 | } |
| 161 | |
| 162 | /* |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 163 | * Expand the file descriptor table. |
| 164 | * This function will allocate a new fdtable and both fd array and fdset, of |
| 165 | * the given size. |
| 166 | * Return <0 error code on error; 1 on successful completion. |
| 167 | * The files->file_lock should be held on entry, and will be held on exit. |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 168 | */ |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 169 | static int expand_fdtable(struct files_struct *files, unsigned int nr) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 170 | __releases(files->file_lock) |
| 171 | __acquires(files->file_lock) |
| 172 | { |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 173 | struct fdtable *new_fdt, *cur_fdt; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 174 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 175 | spin_unlock(&files->file_lock); |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 176 | new_fdt = alloc_fdtable(nr); |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 177 | |
Eric W. Biederman | d74ba04 | 2020-11-20 17:14:35 -0600 | [diff] [blame] | 178 | /* make sure all fd_install() have seen resize_in_progress |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 179 | * or have finished their rcu_read_lock_sched() section. |
| 180 | */ |
| 181 | if (atomic_read(&files->count) > 1) |
Paul E. McKenney | c93ffc1 | 2018-11-05 17:31:31 -0800 | [diff] [blame] | 182 | synchronize_rcu(); |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 183 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 184 | spin_lock(&files->file_lock); |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 185 | if (!new_fdt) |
| 186 | return -ENOMEM; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 187 | /* |
Al Viro | 5c598b3 | 2008-04-27 20:04:15 -0400 | [diff] [blame] | 188 | * extremely unlikely race - sysctl_nr_open decreased between the check in |
| 189 | * caller and alloc_fdtable(). Cheaper to catch it here... |
| 190 | */ |
| 191 | if (unlikely(new_fdt->max_fds <= nr)) { |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 192 | __free_fdtable(new_fdt); |
Al Viro | 5c598b3 | 2008-04-27 20:04:15 -0400 | [diff] [blame] | 193 | return -EMFILE; |
| 194 | } |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 195 | cur_fdt = files_fdtable(files); |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 196 | BUG_ON(nr < cur_fdt->max_fds); |
| 197 | copy_fdtable(new_fdt, cur_fdt); |
| 198 | rcu_assign_pointer(files->fdt, new_fdt); |
| 199 | if (cur_fdt != &files->fdtab) |
| 200 | call_rcu(&cur_fdt->rcu, free_fdtable_rcu); |
Eric W. Biederman | d74ba04 | 2020-11-20 17:14:35 -0600 | [diff] [blame] | 201 | /* coupled with smp_rmb() in fd_install() */ |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 202 | smp_wmb(); |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 203 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 204 | } |
| 205 | |
| 206 | /* |
| 207 | * Expand files. |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 208 | * This function will expand the file structures, if the requested size exceeds |
| 209 | * the current capacity and there is room for expansion. |
| 210 | * Return <0 error code on error; 0 when nothing done; 1 when files were |
| 211 | * expanded and execution may have blocked. |
| 212 | * The files->file_lock should be held on entry, and will be held on exit. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 213 | */ |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 214 | static int expand_files(struct files_struct *files, unsigned int nr) |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 215 | __releases(files->file_lock) |
| 216 | __acquires(files->file_lock) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 217 | { |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 218 | struct fdtable *fdt; |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 219 | int expanded = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 220 | |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 221 | repeat: |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 222 | fdt = files_fdtable(files); |
Al Viro | 4e1e018 | 2008-07-26 16:01:20 -0400 | [diff] [blame] | 223 | |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 224 | /* Do we need to expand? */ |
Vadim Lobanov | bbea9f6 | 2006-12-10 02:21:12 -0800 | [diff] [blame] | 225 | if (nr < fdt->max_fds) |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 226 | return expanded; |
Al Viro | 4e1e018 | 2008-07-26 16:01:20 -0400 | [diff] [blame] | 227 | |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 228 | /* Can we expand? */ |
Eric Dumazet | 9cfe015 | 2008-02-06 01:37:16 -0800 | [diff] [blame] | 229 | if (nr >= sysctl_nr_open) |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 230 | return -EMFILE; |
| 231 | |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 232 | if (unlikely(files->resize_in_progress)) { |
| 233 | spin_unlock(&files->file_lock); |
| 234 | expanded = 1; |
| 235 | wait_event(files->resize_wait, !files->resize_in_progress); |
| 236 | spin_lock(&files->file_lock); |
| 237 | goto repeat; |
| 238 | } |
| 239 | |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 240 | /* All good, so we try */ |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 241 | files->resize_in_progress = true; |
| 242 | expanded = expand_fdtable(files, nr); |
| 243 | files->resize_in_progress = false; |
| 244 | |
| 245 | wake_up_all(&files->resize_wait); |
| 246 | return expanded; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 247 | } |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 248 | |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 249 | static inline void __set_close_on_exec(unsigned int fd, struct fdtable *fdt) |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 250 | { |
| 251 | __set_bit(fd, fdt->close_on_exec); |
| 252 | } |
| 253 | |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 254 | static inline void __clear_close_on_exec(unsigned int fd, struct fdtable *fdt) |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 255 | { |
Linus Torvalds | fc90888 | 2015-10-31 16:06:40 -0700 | [diff] [blame] | 256 | if (test_bit(fd, fdt->close_on_exec)) |
| 257 | __clear_bit(fd, fdt->close_on_exec); |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 258 | } |
| 259 | |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 260 | static inline void __set_open_fd(unsigned int fd, struct fdtable *fdt) |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 261 | { |
| 262 | __set_bit(fd, fdt->open_fds); |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 263 | fd /= BITS_PER_LONG; |
| 264 | if (!~fdt->open_fds[fd]) |
| 265 | __set_bit(fd, fdt->full_fds_bits); |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 266 | } |
| 267 | |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 268 | static inline void __clear_open_fd(unsigned int fd, struct fdtable *fdt) |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 269 | { |
| 270 | __clear_bit(fd, fdt->open_fds); |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 271 | __clear_bit(fd / BITS_PER_LONG, fdt->full_fds_bits); |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 272 | } |
| 273 | |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 274 | static unsigned int count_open_files(struct fdtable *fdt) |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 275 | { |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 276 | unsigned int size = fdt->max_fds; |
| 277 | unsigned int i; |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 278 | |
| 279 | /* Find the last open fd */ |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 280 | for (i = size / BITS_PER_LONG; i > 0; ) { |
| 281 | if (fdt->open_fds[--i]) |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 282 | break; |
| 283 | } |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 284 | i = (i + 1) * BITS_PER_LONG; |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 285 | return i; |
| 286 | } |
| 287 | |
Linus Torvalds | 1c24a18 | 2022-03-29 15:06:39 -0700 | [diff] [blame] | 288 | /* |
| 289 | * Note that a sane fdtable size always has to be a multiple of |
| 290 | * BITS_PER_LONG, since we have bitmaps that are sized by this. |
| 291 | * |
| 292 | * 'max_fds' will normally already be properly aligned, but it |
| 293 | * turns out that in the close_range() -> __close_range() -> |
| 294 | * unshare_fd() -> dup_fd() -> sane_fdtable_size() we can end |
| 295 | * up having a 'max_fds' value that isn't already aligned. |
| 296 | * |
| 297 | * Rather than make close_range() have to worry about this, |
| 298 | * just make that BITS_PER_LONG alignment be part of a sane |
| 299 | * fdtable size. Becuase that's really what it is. |
| 300 | */ |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 301 | static unsigned int sane_fdtable_size(struct fdtable *fdt, unsigned int max_fds) |
| 302 | { |
| 303 | unsigned int count; |
| 304 | |
| 305 | count = count_open_files(fdt); |
| 306 | if (max_fds < NR_OPEN_DEFAULT) |
| 307 | max_fds = NR_OPEN_DEFAULT; |
Linus Torvalds | d888c83 | 2022-03-29 23:29:18 -0700 | [diff] [blame] | 308 | return ALIGN(min(count, max_fds), BITS_PER_LONG); |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 309 | } |
| 310 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 311 | /* |
| 312 | * Allocate a new files structure and copy contents from the |
| 313 | * passed in files structure. |
| 314 | * errorp will be valid only when the returned files_struct is NULL. |
| 315 | */ |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 316 | struct files_struct *dup_fd(struct files_struct *oldf, unsigned int max_fds, int *errorp) |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 317 | { |
| 318 | struct files_struct *newf; |
| 319 | struct file **old_fds, **new_fds; |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 320 | unsigned int open_files, i; |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 321 | struct fdtable *old_fdt, *new_fdt; |
| 322 | |
| 323 | *errorp = -ENOMEM; |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 324 | newf = kmem_cache_alloc(files_cachep, GFP_KERNEL); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 325 | if (!newf) |
| 326 | goto out; |
| 327 | |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 328 | atomic_set(&newf->count, 1); |
| 329 | |
| 330 | spin_lock_init(&newf->file_lock); |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 331 | newf->resize_in_progress = false; |
| 332 | init_waitqueue_head(&newf->resize_wait); |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 333 | newf->next_fd = 0; |
| 334 | new_fdt = &newf->fdtab; |
| 335 | new_fdt->max_fds = NR_OPEN_DEFAULT; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 336 | new_fdt->close_on_exec = newf->close_on_exec_init; |
| 337 | new_fdt->open_fds = newf->open_fds_init; |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 338 | new_fdt->full_fds_bits = newf->full_fds_bits_init; |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 339 | new_fdt->fd = &newf->fd_array[0]; |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 340 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 341 | spin_lock(&oldf->file_lock); |
| 342 | old_fdt = files_fdtable(oldf); |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 343 | open_files = sane_fdtable_size(old_fdt, max_fds); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 344 | |
| 345 | /* |
| 346 | * Check whether we need to allocate a larger fd array and fd set. |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 347 | */ |
Al Viro | adbecb1 | 2008-05-08 21:19:42 -0400 | [diff] [blame] | 348 | while (unlikely(open_files > new_fdt->max_fds)) { |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 349 | spin_unlock(&oldf->file_lock); |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 350 | |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 351 | if (new_fdt != &newf->fdtab) |
| 352 | __free_fdtable(new_fdt); |
Al Viro | adbecb1 | 2008-05-08 21:19:42 -0400 | [diff] [blame] | 353 | |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 354 | new_fdt = alloc_fdtable(open_files - 1); |
| 355 | if (!new_fdt) { |
| 356 | *errorp = -ENOMEM; |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 357 | goto out_release; |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 358 | } |
| 359 | |
| 360 | /* beyond sysctl_nr_open; nothing to do */ |
| 361 | if (unlikely(new_fdt->max_fds < open_files)) { |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 362 | __free_fdtable(new_fdt); |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 363 | *errorp = -EMFILE; |
| 364 | goto out_release; |
| 365 | } |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 366 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 367 | /* |
| 368 | * Reacquire the oldf lock and a pointer to its fd table |
| 369 | * who knows it may have a new bigger fd table. We need |
| 370 | * the latest pointer. |
| 371 | */ |
| 372 | spin_lock(&oldf->file_lock); |
| 373 | old_fdt = files_fdtable(oldf); |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 374 | open_files = sane_fdtable_size(old_fdt, max_fds); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 375 | } |
| 376 | |
Eric Biggers | ea5c58e | 2015-11-06 00:32:04 -0600 | [diff] [blame] | 377 | copy_fd_bitmaps(new_fdt, old_fdt, open_files); |
| 378 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 379 | old_fds = old_fdt->fd; |
| 380 | new_fds = new_fdt->fd; |
| 381 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 382 | for (i = open_files; i != 0; i--) { |
| 383 | struct file *f = *old_fds++; |
| 384 | if (f) { |
| 385 | get_file(f); |
| 386 | } else { |
| 387 | /* |
| 388 | * The fd may be claimed in the fd bitmap but not yet |
| 389 | * instantiated in the files array if a sibling thread |
| 390 | * is partway through open(). So make sure that this |
| 391 | * fd is available to the new process. |
| 392 | */ |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 393 | __clear_open_fd(open_files - i, new_fdt); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 394 | } |
| 395 | rcu_assign_pointer(*new_fds++, f); |
| 396 | } |
| 397 | spin_unlock(&oldf->file_lock); |
| 398 | |
Eric Biggers | ea5c58e | 2015-11-06 00:32:04 -0600 | [diff] [blame] | 399 | /* clear the remainder */ |
| 400 | memset(new_fds, 0, (new_fdt->max_fds - open_files) * sizeof(struct file *)); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 401 | |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 402 | rcu_assign_pointer(newf->fdt, new_fdt); |
| 403 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 404 | return newf; |
| 405 | |
| 406 | out_release: |
| 407 | kmem_cache_free(files_cachep, newf); |
| 408 | out: |
| 409 | return NULL; |
| 410 | } |
| 411 | |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 412 | static struct fdtable *close_files(struct files_struct * files) |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 413 | { |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 414 | /* |
| 415 | * It is safe to dereference the fd table without RCU or |
| 416 | * ->file_lock because this is the last reference to the |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 417 | * files structure. |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 418 | */ |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 419 | struct fdtable *fdt = rcu_dereference_raw(files->fdt); |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 420 | unsigned int i, j = 0; |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 421 | |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 422 | for (;;) { |
| 423 | unsigned long set; |
| 424 | i = j * BITS_PER_LONG; |
| 425 | if (i >= fdt->max_fds) |
| 426 | break; |
| 427 | set = fdt->open_fds[j++]; |
| 428 | while (set) { |
| 429 | if (set & 1) { |
| 430 | struct file * file = xchg(&fdt->fd[i], NULL); |
| 431 | if (file) { |
| 432 | filp_close(file, files); |
Paul E. McKenney | 388a4c8 | 2017-10-24 08:39:34 -0700 | [diff] [blame] | 433 | cond_resched(); |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 434 | } |
| 435 | } |
| 436 | i++; |
| 437 | set >>= 1; |
| 438 | } |
| 439 | } |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 440 | |
| 441 | return fdt; |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 442 | } |
| 443 | |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 444 | void put_files_struct(struct files_struct *files) |
| 445 | { |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 446 | if (atomic_dec_and_test(&files->count)) { |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 447 | struct fdtable *fdt = close_files(files); |
| 448 | |
Al Viro | b9e02af | 2012-08-15 20:00:58 -0400 | [diff] [blame] | 449 | /* free the arrays if they are not embedded */ |
| 450 | if (fdt != &files->fdtab) |
| 451 | __free_fdtable(fdt); |
| 452 | kmem_cache_free(files_cachep, files); |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 453 | } |
| 454 | } |
| 455 | |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 456 | void exit_files(struct task_struct *tsk) |
| 457 | { |
| 458 | struct files_struct * files = tsk->files; |
| 459 | |
| 460 | if (files) { |
| 461 | task_lock(tsk); |
| 462 | tsk->files = NULL; |
| 463 | task_unlock(tsk); |
| 464 | put_files_struct(files); |
| 465 | } |
| 466 | } |
| 467 | |
Al Viro | f52111b | 2008-05-08 18:19:16 -0400 | [diff] [blame] | 468 | struct files_struct init_files = { |
| 469 | .count = ATOMIC_INIT(1), |
| 470 | .fdt = &init_files.fdtab, |
| 471 | .fdtab = { |
| 472 | .max_fds = NR_OPEN_DEFAULT, |
| 473 | .fd = &init_files.fd_array[0], |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 474 | .close_on_exec = init_files.close_on_exec_init, |
| 475 | .open_fds = init_files.open_fds_init, |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 476 | .full_fds_bits = init_files.full_fds_bits_init, |
Al Viro | f52111b | 2008-05-08 18:19:16 -0400 | [diff] [blame] | 477 | }, |
Thomas Gleixner | eece09e | 2011-07-17 21:25:03 +0200 | [diff] [blame] | 478 | .file_lock = __SPIN_LOCK_UNLOCKED(init_files.file_lock), |
Shuriyc Chu | 5704a06 | 2019-03-05 15:41:56 -0800 | [diff] [blame] | 479 | .resize_wait = __WAIT_QUEUE_HEAD_INITIALIZER(init_files.resize_wait), |
Al Viro | f52111b | 2008-05-08 18:19:16 -0400 | [diff] [blame] | 480 | }; |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 481 | |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 482 | static unsigned int find_next_fd(struct fdtable *fdt, unsigned int start) |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 483 | { |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 484 | unsigned int maxfd = fdt->max_fds; |
| 485 | unsigned int maxbit = maxfd / BITS_PER_LONG; |
| 486 | unsigned int bitbit = start / BITS_PER_LONG; |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 487 | |
| 488 | bitbit = find_next_zero_bit(fdt->full_fds_bits, maxbit, bitbit) * BITS_PER_LONG; |
| 489 | if (bitbit > maxfd) |
| 490 | return maxfd; |
| 491 | if (bitbit > start) |
| 492 | start = bitbit; |
| 493 | return find_next_zero_bit(fdt->open_fds, maxfd, start); |
| 494 | } |
| 495 | |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 496 | /* |
| 497 | * allocate a file descriptor, mark it busy. |
| 498 | */ |
Eric W. Biederman | aa384d1 | 2020-11-20 17:14:37 -0600 | [diff] [blame] | 499 | static int alloc_fd(unsigned start, unsigned end, unsigned flags) |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 500 | { |
Eric W. Biederman | aa384d1 | 2020-11-20 17:14:37 -0600 | [diff] [blame] | 501 | struct files_struct *files = current->files; |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 502 | unsigned int fd; |
| 503 | int error; |
| 504 | struct fdtable *fdt; |
| 505 | |
| 506 | spin_lock(&files->file_lock); |
| 507 | repeat: |
| 508 | fdt = files_fdtable(files); |
| 509 | fd = start; |
| 510 | if (fd < files->next_fd) |
| 511 | fd = files->next_fd; |
| 512 | |
| 513 | if (fd < fdt->max_fds) |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 514 | fd = find_next_fd(fdt, fd); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 515 | |
Al Viro | f33ff99 | 2012-08-12 16:17:59 -0400 | [diff] [blame] | 516 | /* |
| 517 | * N.B. For clone tasks sharing a files structure, this test |
| 518 | * will limit the total number of files that can be opened. |
| 519 | */ |
| 520 | error = -EMFILE; |
| 521 | if (fd >= end) |
| 522 | goto out; |
| 523 | |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 524 | error = expand_files(files, fd); |
| 525 | if (error < 0) |
| 526 | goto out; |
| 527 | |
| 528 | /* |
| 529 | * If we needed to expand the fs array we |
| 530 | * might have blocked - try again. |
| 531 | */ |
| 532 | if (error) |
| 533 | goto repeat; |
| 534 | |
| 535 | if (start <= files->next_fd) |
| 536 | files->next_fd = fd + 1; |
| 537 | |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 538 | __set_open_fd(fd, fdt); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 539 | if (flags & O_CLOEXEC) |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 540 | __set_close_on_exec(fd, fdt); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 541 | else |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 542 | __clear_close_on_exec(fd, fdt); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 543 | error = fd; |
| 544 | #if 1 |
| 545 | /* Sanity check */ |
Paul E. McKenney | add1f09 | 2014-02-12 12:51:09 -0800 | [diff] [blame] | 546 | if (rcu_access_pointer(fdt->fd[fd]) != NULL) { |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 547 | printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd); |
| 548 | rcu_assign_pointer(fdt->fd[fd], NULL); |
| 549 | } |
| 550 | #endif |
| 551 | |
| 552 | out: |
| 553 | spin_unlock(&files->file_lock); |
| 554 | return error; |
| 555 | } |
| 556 | |
Jens Axboe | 4022e7a | 2020-03-19 19:23:18 -0600 | [diff] [blame] | 557 | int __get_unused_fd_flags(unsigned flags, unsigned long nofile) |
| 558 | { |
Eric W. Biederman | aa384d1 | 2020-11-20 17:14:37 -0600 | [diff] [blame] | 559 | return alloc_fd(0, nofile, flags); |
Jens Axboe | 4022e7a | 2020-03-19 19:23:18 -0600 | [diff] [blame] | 560 | } |
| 561 | |
Al Viro | 1a7bd22 | 2012-08-12 17:18:05 -0400 | [diff] [blame] | 562 | int get_unused_fd_flags(unsigned flags) |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 563 | { |
Jens Axboe | 4022e7a | 2020-03-19 19:23:18 -0600 | [diff] [blame] | 564 | return __get_unused_fd_flags(flags, rlimit(RLIMIT_NOFILE)); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 565 | } |
Al Viro | 1a7bd22 | 2012-08-12 17:18:05 -0400 | [diff] [blame] | 566 | EXPORT_SYMBOL(get_unused_fd_flags); |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 567 | |
| 568 | static void __put_unused_fd(struct files_struct *files, unsigned int fd) |
| 569 | { |
| 570 | struct fdtable *fdt = files_fdtable(files); |
| 571 | __clear_open_fd(fd, fdt); |
| 572 | if (fd < files->next_fd) |
| 573 | files->next_fd = fd; |
| 574 | } |
| 575 | |
| 576 | void put_unused_fd(unsigned int fd) |
| 577 | { |
| 578 | struct files_struct *files = current->files; |
| 579 | spin_lock(&files->file_lock); |
| 580 | __put_unused_fd(files, fd); |
| 581 | spin_unlock(&files->file_lock); |
| 582 | } |
| 583 | |
| 584 | EXPORT_SYMBOL(put_unused_fd); |
| 585 | |
| 586 | /* |
| 587 | * Install a file pointer in the fd array. |
| 588 | * |
| 589 | * The VFS is full of places where we drop the files lock between |
| 590 | * setting the open_fds bitmap and installing the file in the file |
| 591 | * array. At any such point, we are vulnerable to a dup2() race |
| 592 | * installing a file in the array before us. We need to detect this and |
| 593 | * fput() the struct file we are about to overwrite in this case. |
| 594 | * |
| 595 | * It should never happen - if we allow dup2() do it, _really_ bad things |
| 596 | * will follow. |
Al Viro | f869e8a | 2012-08-15 21:06:33 -0400 | [diff] [blame] | 597 | * |
Eric W. Biederman | d74ba04 | 2020-11-20 17:14:35 -0600 | [diff] [blame] | 598 | * This consumes the "file" refcount, so callers should treat it |
| 599 | * as if they had called fput(file). |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 600 | */ |
| 601 | |
Eric W. Biederman | d74ba04 | 2020-11-20 17:14:35 -0600 | [diff] [blame] | 602 | void fd_install(unsigned int fd, struct file *file) |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 603 | { |
Eric W. Biederman | d74ba04 | 2020-11-20 17:14:35 -0600 | [diff] [blame] | 604 | struct files_struct *files = current->files; |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 605 | struct fdtable *fdt; |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 606 | |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 607 | rcu_read_lock_sched(); |
| 608 | |
Mateusz Guzik | c02b1a9 | 2017-10-03 12:58:15 +0200 | [diff] [blame] | 609 | if (unlikely(files->resize_in_progress)) { |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 610 | rcu_read_unlock_sched(); |
Mateusz Guzik | c02b1a9 | 2017-10-03 12:58:15 +0200 | [diff] [blame] | 611 | spin_lock(&files->file_lock); |
| 612 | fdt = files_fdtable(files); |
| 613 | BUG_ON(fdt->fd[fd] != NULL); |
| 614 | rcu_assign_pointer(fdt->fd[fd], file); |
| 615 | spin_unlock(&files->file_lock); |
| 616 | return; |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 617 | } |
| 618 | /* coupled with smp_wmb() in expand_fdtable() */ |
| 619 | smp_rmb(); |
| 620 | fdt = rcu_dereference_sched(files->fdt); |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 621 | BUG_ON(fdt->fd[fd] != NULL); |
| 622 | rcu_assign_pointer(fdt->fd[fd], file); |
Eric Dumazet | 8a81252b | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 623 | rcu_read_unlock_sched(); |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 624 | } |
| 625 | |
| 626 | EXPORT_SYMBOL(fd_install); |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 627 | |
Christian Brauner | f49fd6d | 2021-04-02 10:32:21 +0200 | [diff] [blame] | 628 | /** |
| 629 | * pick_file - return file associatd with fd |
| 630 | * @files: file struct to retrieve file from |
| 631 | * @fd: file descriptor to retrieve file for |
| 632 | * |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 633 | * Context: files_lock must be held. |
Christian Brauner | f49fd6d | 2021-04-02 10:32:21 +0200 | [diff] [blame] | 634 | * |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 635 | * Returns: The file associated with @fd (NULL if @fd is not open) |
Christian Brauner | f49fd6d | 2021-04-02 10:32:21 +0200 | [diff] [blame] | 636 | */ |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 637 | static struct file *pick_file(struct files_struct *files, unsigned fd) |
Al Viro | 483ce1d | 2012-08-19 12:04:24 -0400 | [diff] [blame] | 638 | { |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 639 | struct fdtable *fdt = files_fdtable(files); |
Christian Brauner | f49fd6d | 2021-04-02 10:32:21 +0200 | [diff] [blame] | 640 | struct file *file; |
Al Viro | 483ce1d | 2012-08-19 12:04:24 -0400 | [diff] [blame] | 641 | |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 642 | if (fd >= fdt->max_fds) |
| 643 | return NULL; |
| 644 | |
Theodore Ts'o | 609d544 | 2023-03-06 13:54:50 -0500 | [diff] [blame] | 645 | fd = array_index_nospec(fd, fdt->max_fds); |
Al Viro | 483ce1d | 2012-08-19 12:04:24 -0400 | [diff] [blame] | 646 | file = fdt->fd[fd]; |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 647 | if (file) { |
| 648 | rcu_assign_pointer(fdt->fd[fd], NULL); |
| 649 | __put_unused_fd(files, fd); |
Christian Brauner | f49fd6d | 2021-04-02 10:32:21 +0200 | [diff] [blame] | 650 | } |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 651 | return file; |
| 652 | } |
| 653 | |
Eric W. Biederman | 8760c90 | 2020-11-20 17:14:38 -0600 | [diff] [blame] | 654 | int close_fd(unsigned fd) |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 655 | { |
Eric W. Biederman | 8760c90 | 2020-11-20 17:14:38 -0600 | [diff] [blame] | 656 | struct files_struct *files = current->files; |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 657 | struct file *file; |
| 658 | |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 659 | spin_lock(&files->file_lock); |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 660 | file = pick_file(files, fd); |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 661 | spin_unlock(&files->file_lock); |
| 662 | if (!file) |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 663 | return -EBADF; |
| 664 | |
| 665 | return filp_close(file, files); |
Al Viro | 483ce1d | 2012-08-19 12:04:24 -0400 | [diff] [blame] | 666 | } |
Eric W. Biederman | 8760c90 | 2020-11-20 17:14:38 -0600 | [diff] [blame] | 667 | EXPORT_SYMBOL(close_fd); /* for ksys_close() */ |
Al Viro | 483ce1d | 2012-08-19 12:04:24 -0400 | [diff] [blame] | 668 | |
Christian Brauner | 9b5b8722 | 2021-04-02 10:29:36 +0200 | [diff] [blame] | 669 | /** |
| 670 | * last_fd - return last valid index into fd table |
| 671 | * @cur_fds: files struct |
| 672 | * |
| 673 | * Context: Either rcu read lock or files_lock must be held. |
| 674 | * |
| 675 | * Returns: Last valid index into fdtable. |
| 676 | */ |
| 677 | static inline unsigned last_fd(struct fdtable *fdt) |
| 678 | { |
| 679 | return fdt->max_fds - 1; |
| 680 | } |
| 681 | |
Giuseppe Scrivano | 582f1fb | 2020-11-18 11:47:45 +0100 | [diff] [blame] | 682 | static inline void __range_cloexec(struct files_struct *cur_fds, |
| 683 | unsigned int fd, unsigned int max_fd) |
| 684 | { |
| 685 | struct fdtable *fdt; |
| 686 | |
Christian Brauner | 9b5b8722 | 2021-04-02 10:29:36 +0200 | [diff] [blame] | 687 | /* make sure we're using the correct maximum value */ |
Giuseppe Scrivano | 582f1fb | 2020-11-18 11:47:45 +0100 | [diff] [blame] | 688 | spin_lock(&cur_fds->file_lock); |
| 689 | fdt = files_fdtable(cur_fds); |
Christian Brauner | 9b5b8722 | 2021-04-02 10:29:36 +0200 | [diff] [blame] | 690 | max_fd = min(last_fd(fdt), max_fd); |
| 691 | if (fd <= max_fd) |
| 692 | bitmap_set(fdt->close_on_exec, fd, max_fd - fd + 1); |
Giuseppe Scrivano | 582f1fb | 2020-11-18 11:47:45 +0100 | [diff] [blame] | 693 | spin_unlock(&cur_fds->file_lock); |
| 694 | } |
| 695 | |
| 696 | static inline void __range_close(struct files_struct *cur_fds, unsigned int fd, |
| 697 | unsigned int max_fd) |
| 698 | { |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 699 | unsigned n; |
| 700 | |
| 701 | rcu_read_lock(); |
| 702 | n = last_fd(files_fdtable(cur_fds)); |
| 703 | rcu_read_unlock(); |
| 704 | max_fd = min(max_fd, n); |
| 705 | |
Giuseppe Scrivano | 582f1fb | 2020-11-18 11:47:45 +0100 | [diff] [blame] | 706 | while (fd <= max_fd) { |
| 707 | struct file *file; |
| 708 | |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 709 | spin_lock(&cur_fds->file_lock); |
Giuseppe Scrivano | 582f1fb | 2020-11-18 11:47:45 +0100 | [diff] [blame] | 710 | file = pick_file(cur_fds, fd++); |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 711 | spin_unlock(&cur_fds->file_lock); |
| 712 | |
| 713 | if (file) { |
Christian Brauner | f49fd6d | 2021-04-02 10:32:21 +0200 | [diff] [blame] | 714 | /* found a valid file to close */ |
| 715 | filp_close(file, cur_fds); |
| 716 | cond_resched(); |
Christian Brauner | f49fd6d | 2021-04-02 10:32:21 +0200 | [diff] [blame] | 717 | } |
Giuseppe Scrivano | 582f1fb | 2020-11-18 11:47:45 +0100 | [diff] [blame] | 718 | } |
| 719 | } |
| 720 | |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 721 | /** |
| 722 | * __close_range() - Close all file descriptors in a given range. |
| 723 | * |
| 724 | * @fd: starting file descriptor to close |
| 725 | * @max_fd: last file descriptor to close |
| 726 | * |
| 727 | * This closes a range of file descriptors. All file descriptors |
| 728 | * from @fd up to and including @max_fd are closed. |
| 729 | */ |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 730 | int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 731 | { |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 732 | struct task_struct *me = current; |
| 733 | struct files_struct *cur_fds = me->files, *fds = NULL; |
| 734 | |
Giuseppe Scrivano | 582f1fb | 2020-11-18 11:47:45 +0100 | [diff] [blame] | 735 | if (flags & ~(CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC)) |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 736 | return -EINVAL; |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 737 | |
| 738 | if (fd > max_fd) |
| 739 | return -EINVAL; |
| 740 | |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 741 | if (flags & CLOSE_RANGE_UNSHARE) { |
| 742 | int ret; |
| 743 | unsigned int max_unshare_fds = NR_OPEN_MAX; |
| 744 | |
| 745 | /* |
Christian Brauner | 03ba0fe | 2021-04-02 10:38:09 +0200 | [diff] [blame] | 746 | * If the caller requested all fds to be made cloexec we always |
| 747 | * copy all of the file descriptors since they still want to |
| 748 | * use them. |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 749 | */ |
Christian Brauner | 03ba0fe | 2021-04-02 10:38:09 +0200 | [diff] [blame] | 750 | if (!(flags & CLOSE_RANGE_CLOEXEC)) { |
| 751 | /* |
| 752 | * If the requested range is greater than the current |
| 753 | * maximum, we're closing everything so only copy all |
| 754 | * file descriptors beneath the lowest file descriptor. |
| 755 | */ |
| 756 | rcu_read_lock(); |
| 757 | if (max_fd >= last_fd(files_fdtable(cur_fds))) |
| 758 | max_unshare_fds = fd; |
| 759 | rcu_read_unlock(); |
| 760 | } |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 761 | |
| 762 | ret = unshare_fd(CLONE_FILES, max_unshare_fds, &fds); |
| 763 | if (ret) |
| 764 | return ret; |
| 765 | |
| 766 | /* |
| 767 | * We used to share our file descriptor table, and have now |
| 768 | * created a private one, make sure we're using it below. |
| 769 | */ |
| 770 | if (fds) |
| 771 | swap(cur_fds, fds); |
| 772 | } |
| 773 | |
Giuseppe Scrivano | 582f1fb | 2020-11-18 11:47:45 +0100 | [diff] [blame] | 774 | if (flags & CLOSE_RANGE_CLOEXEC) |
| 775 | __range_cloexec(cur_fds, fd, max_fd); |
| 776 | else |
| 777 | __range_close(cur_fds, fd, max_fd); |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 778 | |
Christian Brauner | 60997c3 | 2020-06-03 21:48:55 +0200 | [diff] [blame] | 779 | if (fds) { |
| 780 | /* |
| 781 | * We're done closing the files we were supposed to. Time to install |
| 782 | * the new file descriptor table and drop the old one. |
| 783 | */ |
| 784 | task_lock(me); |
| 785 | me->files = cur_fds; |
| 786 | task_unlock(me); |
| 787 | put_files_struct(fds); |
| 788 | } |
| 789 | |
Christian Brauner | 278a5fb | 2019-05-24 11:30:34 +0200 | [diff] [blame] | 790 | return 0; |
| 791 | } |
| 792 | |
Todd Kjos | 80cd795 | 2018-12-14 15:58:21 -0800 | [diff] [blame] | 793 | /* |
Jens Axboe | 53dec2e | 2021-01-19 15:41:52 -0700 | [diff] [blame] | 794 | * See close_fd_get_file() below, this variant assumes current->files->file_lock |
| 795 | * is held. |
| 796 | */ |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 797 | struct file *__close_fd_get_file(unsigned int fd) |
Jens Axboe | 53dec2e | 2021-01-19 15:41:52 -0700 | [diff] [blame] | 798 | { |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 799 | return pick_file(current->files, fd); |
Jens Axboe | 53dec2e | 2021-01-19 15:41:52 -0700 | [diff] [blame] | 800 | } |
| 801 | |
| 802 | /* |
Eric W. Biederman | 9fe83c4 | 2020-11-20 17:14:40 -0600 | [diff] [blame] | 803 | * variant of close_fd that gets a ref on the file for later fput. |
Al Viro | 40a1926 | 2022-06-05 14:01:42 -0400 | [diff] [blame] | 804 | * The caller must ensure that filp_close() called on the file. |
Todd Kjos | 80cd795 | 2018-12-14 15:58:21 -0800 | [diff] [blame] | 805 | */ |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 806 | struct file *close_fd_get_file(unsigned int fd) |
Todd Kjos | 80cd795 | 2018-12-14 15:58:21 -0800 | [diff] [blame] | 807 | { |
| 808 | struct files_struct *files = current->files; |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 809 | struct file *file; |
Todd Kjos | 80cd795 | 2018-12-14 15:58:21 -0800 | [diff] [blame] | 810 | |
| 811 | spin_lock(&files->file_lock); |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 812 | file = pick_file(files, fd); |
Todd Kjos | 80cd795 | 2018-12-14 15:58:21 -0800 | [diff] [blame] | 813 | spin_unlock(&files->file_lock); |
Todd Kjos | 80cd795 | 2018-12-14 15:58:21 -0800 | [diff] [blame] | 814 | |
Al Viro | 6319194e | 2022-05-12 17:08:03 -0400 | [diff] [blame] | 815 | return file; |
Todd Kjos | 80cd795 | 2018-12-14 15:58:21 -0800 | [diff] [blame] | 816 | } |
| 817 | |
Al Viro | 6a6d27d | 2012-08-21 09:56:33 -0400 | [diff] [blame] | 818 | void do_close_on_exec(struct files_struct *files) |
| 819 | { |
| 820 | unsigned i; |
| 821 | struct fdtable *fdt; |
| 822 | |
| 823 | /* exec unshares first */ |
Al Viro | 6a6d27d | 2012-08-21 09:56:33 -0400 | [diff] [blame] | 824 | spin_lock(&files->file_lock); |
| 825 | for (i = 0; ; i++) { |
| 826 | unsigned long set; |
| 827 | unsigned fd = i * BITS_PER_LONG; |
| 828 | fdt = files_fdtable(files); |
| 829 | if (fd >= fdt->max_fds) |
| 830 | break; |
| 831 | set = fdt->close_on_exec[i]; |
| 832 | if (!set) |
| 833 | continue; |
| 834 | fdt->close_on_exec[i] = 0; |
| 835 | for ( ; set ; fd++, set >>= 1) { |
| 836 | struct file *file; |
| 837 | if (!(set & 1)) |
| 838 | continue; |
| 839 | file = fdt->fd[fd]; |
| 840 | if (!file) |
| 841 | continue; |
| 842 | rcu_assign_pointer(fdt->fd[fd], NULL); |
| 843 | __put_unused_fd(files, fd); |
| 844 | spin_unlock(&files->file_lock); |
| 845 | filp_close(file, files); |
| 846 | cond_resched(); |
| 847 | spin_lock(&files->file_lock); |
| 848 | } |
| 849 | |
| 850 | } |
| 851 | spin_unlock(&files->file_lock); |
| 852 | } |
| 853 | |
Linus Torvalds | e386dfc | 2021-12-10 14:00:15 -0800 | [diff] [blame] | 854 | static inline struct file *__fget_files_rcu(struct files_struct *files, |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 855 | unsigned int fd, fmode_t mask) |
Linus Torvalds | e386dfc | 2021-12-10 14:00:15 -0800 | [diff] [blame] | 856 | { |
| 857 | for (;;) { |
| 858 | struct file *file; |
| 859 | struct fdtable *fdt = rcu_dereference_raw(files->fdt); |
| 860 | struct file __rcu **fdentry; |
| 861 | |
| 862 | if (unlikely(fd >= fdt->max_fds)) |
| 863 | return NULL; |
| 864 | |
| 865 | fdentry = fdt->fd + array_index_nospec(fd, fdt->max_fds); |
| 866 | file = rcu_dereference_raw(*fdentry); |
| 867 | if (unlikely(!file)) |
| 868 | return NULL; |
| 869 | |
| 870 | if (unlikely(file->f_mode & mask)) |
| 871 | return NULL; |
| 872 | |
| 873 | /* |
| 874 | * Ok, we have a file pointer. However, because we do |
| 875 | * this all locklessly under RCU, we may be racing with |
| 876 | * that file being closed. |
| 877 | * |
| 878 | * Such a race can take two forms: |
| 879 | * |
| 880 | * (a) the file ref already went down to zero, |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 881 | * and get_file_rcu() fails. Just try again: |
Linus Torvalds | e386dfc | 2021-12-10 14:00:15 -0800 | [diff] [blame] | 882 | */ |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 883 | if (unlikely(!get_file_rcu(file))) |
Linus Torvalds | e386dfc | 2021-12-10 14:00:15 -0800 | [diff] [blame] | 884 | continue; |
| 885 | |
| 886 | /* |
| 887 | * (b) the file table entry has changed under us. |
| 888 | * Note that we don't need to re-check the 'fdt->fd' |
| 889 | * pointer having changed, because it always goes |
| 890 | * hand-in-hand with 'fdt'. |
| 891 | * |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 892 | * If so, we need to put our ref and try again. |
Linus Torvalds | e386dfc | 2021-12-10 14:00:15 -0800 | [diff] [blame] | 893 | */ |
| 894 | if (unlikely(rcu_dereference_raw(files->fdt) != fdt) || |
| 895 | unlikely(rcu_dereference_raw(*fdentry) != file)) { |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 896 | fput(file); |
Linus Torvalds | e386dfc | 2021-12-10 14:00:15 -0800 | [diff] [blame] | 897 | continue; |
| 898 | } |
| 899 | |
| 900 | /* |
| 901 | * Ok, we have a ref to the file, and checked that it |
| 902 | * still exists. |
| 903 | */ |
| 904 | return file; |
| 905 | } |
| 906 | } |
| 907 | |
Sargun Dhillon | 5e876fb | 2020-01-07 09:59:24 -0800 | [diff] [blame] | 908 | static struct file *__fget_files(struct files_struct *files, unsigned int fd, |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 909 | fmode_t mask) |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 910 | { |
Oleg Nesterov | 1deb46e | 2014-01-13 16:48:19 +0100 | [diff] [blame] | 911 | struct file *file; |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 912 | |
| 913 | rcu_read_lock(); |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 914 | file = __fget_files_rcu(files, fd, mask); |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 915 | rcu_read_unlock(); |
| 916 | |
| 917 | return file; |
| 918 | } |
| 919 | |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 920 | static inline struct file *__fget(unsigned int fd, fmode_t mask) |
Sargun Dhillon | 5e876fb | 2020-01-07 09:59:24 -0800 | [diff] [blame] | 921 | { |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 922 | return __fget_files(current->files, fd, mask); |
Jens Axboe | 091141a | 2018-11-21 10:32:39 -0700 | [diff] [blame] | 923 | } |
| 924 | |
Oleg Nesterov | 1deb46e | 2014-01-13 16:48:19 +0100 | [diff] [blame] | 925 | struct file *fget(unsigned int fd) |
| 926 | { |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 927 | return __fget(fd, FMODE_PATH); |
Oleg Nesterov | 1deb46e | 2014-01-13 16:48:19 +0100 | [diff] [blame] | 928 | } |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 929 | EXPORT_SYMBOL(fget); |
| 930 | |
| 931 | struct file *fget_raw(unsigned int fd) |
| 932 | { |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 933 | return __fget(fd, 0); |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 934 | } |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 935 | EXPORT_SYMBOL(fget_raw); |
| 936 | |
Sargun Dhillon | 5e876fb | 2020-01-07 09:59:24 -0800 | [diff] [blame] | 937 | struct file *fget_task(struct task_struct *task, unsigned int fd) |
| 938 | { |
| 939 | struct file *file = NULL; |
| 940 | |
| 941 | task_lock(task); |
| 942 | if (task->files) |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 943 | file = __fget_files(task->files, fd, 0); |
Sargun Dhillon | 5e876fb | 2020-01-07 09:59:24 -0800 | [diff] [blame] | 944 | task_unlock(task); |
| 945 | |
| 946 | return file; |
| 947 | } |
| 948 | |
Eric W. Biederman | 3a879fb | 2020-11-20 17:14:28 -0600 | [diff] [blame] | 949 | struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd) |
| 950 | { |
| 951 | /* Must be called with rcu_read_lock held */ |
| 952 | struct files_struct *files; |
| 953 | struct file *file = NULL; |
| 954 | |
| 955 | task_lock(task); |
| 956 | files = task->files; |
| 957 | if (files) |
| 958 | file = files_lookup_fd_rcu(files, fd); |
| 959 | task_unlock(task); |
| 960 | |
| 961 | return file; |
| 962 | } |
| 963 | |
Eric W. Biederman | e9a53ae | 2020-11-20 17:14:31 -0600 | [diff] [blame] | 964 | struct file *task_lookup_next_fd_rcu(struct task_struct *task, unsigned int *ret_fd) |
| 965 | { |
| 966 | /* Must be called with rcu_read_lock held */ |
| 967 | struct files_struct *files; |
| 968 | unsigned int fd = *ret_fd; |
| 969 | struct file *file = NULL; |
| 970 | |
| 971 | task_lock(task); |
| 972 | files = task->files; |
| 973 | if (files) { |
| 974 | for (; fd < files_fdtable(files)->max_fds; fd++) { |
| 975 | file = files_lookup_fd_rcu(files, fd); |
| 976 | if (file) |
| 977 | break; |
| 978 | } |
| 979 | } |
| 980 | task_unlock(task); |
| 981 | *ret_fd = fd; |
| 982 | return file; |
| 983 | } |
Andreas Gruenbacher | 4480c27 | 2022-06-08 16:22:55 +0200 | [diff] [blame] | 984 | EXPORT_SYMBOL(task_lookup_next_fd_rcu); |
Eric W. Biederman | e9a53ae | 2020-11-20 17:14:31 -0600 | [diff] [blame] | 985 | |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 986 | /* |
| 987 | * Lightweight file lookup - no refcnt increment if fd table isn't shared. |
| 988 | * |
| 989 | * You can use this instead of fget if you satisfy all of the following |
| 990 | * conditions: |
| 991 | * 1) You must call fput_light before exiting the syscall and returning control |
| 992 | * to userspace (i.e. you cannot remember the returned struct file * after |
| 993 | * returning to userspace). |
| 994 | * 2) You must not call filp_close on the returned struct file * in between |
| 995 | * calls to fget_light and fput_light. |
| 996 | * 3) You must not clone the current task in between the calls to fget_light |
| 997 | * and fput_light. |
| 998 | * |
| 999 | * The fput_needed flag returned by fget_light should be passed to the |
| 1000 | * corresponding fput_light. |
| 1001 | */ |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1002 | static unsigned long __fget_light(unsigned int fd, fmode_t mask) |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 1003 | { |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 1004 | struct files_struct *files = current->files; |
Oleg Nesterov | ad46183 | 2014-01-13 16:48:40 +0100 | [diff] [blame] | 1005 | struct file *file; |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 1006 | |
Jann Horn | 7ee47dc | 2022-10-31 18:52:56 +0100 | [diff] [blame] | 1007 | /* |
| 1008 | * If another thread is concurrently calling close_fd() followed |
| 1009 | * by put_files_struct(), we must not observe the old table |
| 1010 | * entry combined with the new refcount - otherwise we could |
| 1011 | * return a file that is concurrently being freed. |
| 1012 | * |
| 1013 | * atomic_read_acquire() pairs with atomic_dec_and_test() in |
| 1014 | * put_files_struct(). |
| 1015 | */ |
| 1016 | if (atomic_read_acquire(&files->count) == 1) { |
Eric W. Biederman | bebf684 | 2020-11-20 17:14:24 -0600 | [diff] [blame] | 1017 | file = files_lookup_fd_raw(files, fd); |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1018 | if (!file || unlikely(file->f_mode & mask)) |
| 1019 | return 0; |
| 1020 | return (unsigned long)file; |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 1021 | } else { |
Gou Hao | 81132a3 | 2021-11-02 10:46:48 +0800 | [diff] [blame] | 1022 | file = __fget(fd, mask); |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1023 | if (!file) |
| 1024 | return 0; |
| 1025 | return FDPUT_FPUT | (unsigned long)file; |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 1026 | } |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 1027 | } |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1028 | unsigned long __fdget(unsigned int fd) |
Oleg Nesterov | ad46183 | 2014-01-13 16:48:40 +0100 | [diff] [blame] | 1029 | { |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1030 | return __fget_light(fd, FMODE_PATH); |
Oleg Nesterov | ad46183 | 2014-01-13 16:48:40 +0100 | [diff] [blame] | 1031 | } |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1032 | EXPORT_SYMBOL(__fdget); |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 1033 | |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1034 | unsigned long __fdget_raw(unsigned int fd) |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 1035 | { |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1036 | return __fget_light(fd, 0); |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 1037 | } |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1038 | |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1039 | unsigned long __fdget_pos(unsigned int fd) |
| 1040 | { |
Eric Biggers | 99aea68 | 2014-03-16 15:47:48 -0500 | [diff] [blame] | 1041 | unsigned long v = __fdget(fd); |
| 1042 | struct file *file = (struct file *)(v & ~3); |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1043 | |
Linus Torvalds | 2be7d34 | 2019-11-26 11:34:06 -0800 | [diff] [blame] | 1044 | if (file && (file->f_mode & FMODE_ATOMIC_POS)) { |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1045 | if (file_count(file) > 1) { |
| 1046 | v |= FDPUT_POS_UNLOCK; |
| 1047 | mutex_lock(&file->f_pos_lock); |
| 1048 | } |
| 1049 | } |
Eric Biggers | 99aea68 | 2014-03-16 15:47:48 -0500 | [diff] [blame] | 1050 | return v; |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1051 | } |
| 1052 | |
Al Viro | 63b6df1 | 2016-04-20 17:08:21 -0400 | [diff] [blame] | 1053 | void __f_unlock_pos(struct file *f) |
| 1054 | { |
| 1055 | mutex_unlock(&f->f_pos_lock); |
| 1056 | } |
| 1057 | |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 1058 | /* |
| 1059 | * We only lock f_pos if we have threads or if the file might be |
| 1060 | * shared with another process. In both cases we'll have an elevated |
| 1061 | * file count (done either by fdget() or by fork()). |
| 1062 | */ |
| 1063 | |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1064 | void set_close_on_exec(unsigned int fd, int flag) |
| 1065 | { |
| 1066 | struct files_struct *files = current->files; |
| 1067 | struct fdtable *fdt; |
| 1068 | spin_lock(&files->file_lock); |
| 1069 | fdt = files_fdtable(files); |
| 1070 | if (flag) |
| 1071 | __set_close_on_exec(fd, fdt); |
| 1072 | else |
| 1073 | __clear_close_on_exec(fd, fdt); |
| 1074 | spin_unlock(&files->file_lock); |
| 1075 | } |
| 1076 | |
| 1077 | bool get_close_on_exec(unsigned int fd) |
| 1078 | { |
| 1079 | struct files_struct *files = current->files; |
| 1080 | struct fdtable *fdt; |
| 1081 | bool res; |
| 1082 | rcu_read_lock(); |
| 1083 | fdt = files_fdtable(files); |
| 1084 | res = close_on_exec(fd, fdt); |
| 1085 | rcu_read_unlock(); |
| 1086 | return res; |
| 1087 | } |
| 1088 | |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 1089 | static int do_dup2(struct files_struct *files, |
| 1090 | struct file *file, unsigned fd, unsigned flags) |
Al Viro | e983094 | 2014-08-31 14:12:09 -0400 | [diff] [blame] | 1091 | __releases(&files->file_lock) |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 1092 | { |
| 1093 | struct file *tofree; |
| 1094 | struct fdtable *fdt; |
| 1095 | |
| 1096 | /* |
| 1097 | * We need to detect attempts to do dup2() over allocated but still |
| 1098 | * not finished descriptor. NB: OpenBSD avoids that at the price of |
| 1099 | * extra work in their equivalent of fget() - they insert struct |
| 1100 | * file immediately after grabbing descriptor, mark it larval if |
| 1101 | * more work (e.g. actual opening) is needed and make sure that |
| 1102 | * fget() treats larval files as absent. Potentially interesting, |
| 1103 | * but while extra work in fget() is trivial, locking implications |
| 1104 | * and amount of surgery on open()-related paths in VFS are not. |
| 1105 | * FreeBSD fails with -EBADF in the same situation, NetBSD "solution" |
| 1106 | * deadlocks in rather amusing ways, AFAICS. All of that is out of |
| 1107 | * scope of POSIX or SUS, since neither considers shared descriptor |
| 1108 | * tables and this condition does not arise without those. |
| 1109 | */ |
| 1110 | fdt = files_fdtable(files); |
| 1111 | tofree = fdt->fd[fd]; |
| 1112 | if (!tofree && fd_is_open(fd, fdt)) |
| 1113 | goto Ebusy; |
| 1114 | get_file(file); |
| 1115 | rcu_assign_pointer(fdt->fd[fd], file); |
| 1116 | __set_open_fd(fd, fdt); |
| 1117 | if (flags & O_CLOEXEC) |
| 1118 | __set_close_on_exec(fd, fdt); |
| 1119 | else |
| 1120 | __clear_close_on_exec(fd, fdt); |
| 1121 | spin_unlock(&files->file_lock); |
| 1122 | |
| 1123 | if (tofree) |
| 1124 | filp_close(tofree, files); |
| 1125 | |
| 1126 | return fd; |
| 1127 | |
| 1128 | Ebusy: |
| 1129 | spin_unlock(&files->file_lock); |
| 1130 | return -EBUSY; |
| 1131 | } |
| 1132 | |
| 1133 | int replace_fd(unsigned fd, struct file *file, unsigned flags) |
| 1134 | { |
| 1135 | int err; |
| 1136 | struct files_struct *files = current->files; |
| 1137 | |
| 1138 | if (!file) |
Eric W. Biederman | 8760c90 | 2020-11-20 17:14:38 -0600 | [diff] [blame] | 1139 | return close_fd(fd); |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 1140 | |
| 1141 | if (fd >= rlimit(RLIMIT_NOFILE)) |
Al Viro | 08f05c4 | 2012-10-31 03:37:48 +0000 | [diff] [blame] | 1142 | return -EBADF; |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 1143 | |
| 1144 | spin_lock(&files->file_lock); |
| 1145 | err = expand_files(files, fd); |
| 1146 | if (unlikely(err < 0)) |
| 1147 | goto out_unlock; |
| 1148 | return do_dup2(files, file, fd, flags); |
| 1149 | |
| 1150 | out_unlock: |
| 1151 | spin_unlock(&files->file_lock); |
| 1152 | return err; |
| 1153 | } |
| 1154 | |
Kees Cook | 6659061 | 2020-06-10 08:20:05 -0700 | [diff] [blame] | 1155 | /** |
| 1156 | * __receive_fd() - Install received file into file descriptor table |
Kees Cook | 6659061 | 2020-06-10 08:20:05 -0700 | [diff] [blame] | 1157 | * @file: struct file that was received from another process |
| 1158 | * @ufd: __user pointer to write new fd number to |
| 1159 | * @o_flags: the O_* flags to apply to the new fd entry |
| 1160 | * |
| 1161 | * Installs a received file into the file descriptor table, with appropriate |
Kees Cook | deefa7f | 2020-06-10 20:47:45 -0700 | [diff] [blame] | 1162 | * checks and count updates. Optionally writes the fd number to userspace, if |
| 1163 | * @ufd is non-NULL. |
Kees Cook | 6659061 | 2020-06-10 08:20:05 -0700 | [diff] [blame] | 1164 | * |
| 1165 | * This helper handles its own reference counting of the incoming |
| 1166 | * struct file. |
| 1167 | * |
Kees Cook | deefa7f | 2020-06-10 20:47:45 -0700 | [diff] [blame] | 1168 | * Returns newly install fd or -ve on error. |
Kees Cook | 6659061 | 2020-06-10 08:20:05 -0700 | [diff] [blame] | 1169 | */ |
Christoph Hellwig | 42eb0d5 | 2021-03-25 09:22:09 +0100 | [diff] [blame] | 1170 | int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags) |
Kees Cook | 6659061 | 2020-06-10 08:20:05 -0700 | [diff] [blame] | 1171 | { |
| 1172 | int new_fd; |
| 1173 | int error; |
| 1174 | |
| 1175 | error = security_file_receive(file); |
| 1176 | if (error) |
| 1177 | return error; |
| 1178 | |
Christoph Hellwig | 42eb0d5 | 2021-03-25 09:22:09 +0100 | [diff] [blame] | 1179 | new_fd = get_unused_fd_flags(o_flags); |
| 1180 | if (new_fd < 0) |
| 1181 | return new_fd; |
Kees Cook | 6659061 | 2020-06-10 08:20:05 -0700 | [diff] [blame] | 1182 | |
Kees Cook | deefa7f | 2020-06-10 20:47:45 -0700 | [diff] [blame] | 1183 | if (ufd) { |
| 1184 | error = put_user(new_fd, ufd); |
| 1185 | if (error) { |
Christoph Hellwig | 42eb0d5 | 2021-03-25 09:22:09 +0100 | [diff] [blame] | 1186 | put_unused_fd(new_fd); |
Kees Cook | deefa7f | 2020-06-10 20:47:45 -0700 | [diff] [blame] | 1187 | return error; |
| 1188 | } |
Kees Cook | 6659061 | 2020-06-10 08:20:05 -0700 | [diff] [blame] | 1189 | } |
| 1190 | |
Christoph Hellwig | 42eb0d5 | 2021-03-25 09:22:09 +0100 | [diff] [blame] | 1191 | fd_install(new_fd, get_file(file)); |
| 1192 | __receive_sock(file); |
| 1193 | return new_fd; |
| 1194 | } |
Kees Cook | 17381715 | 2020-06-10 08:46:58 -0700 | [diff] [blame] | 1195 | |
Christoph Hellwig | 42eb0d5 | 2021-03-25 09:22:09 +0100 | [diff] [blame] | 1196 | int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags) |
| 1197 | { |
| 1198 | int error; |
| 1199 | |
| 1200 | error = security_file_receive(file); |
| 1201 | if (error) |
| 1202 | return error; |
| 1203 | error = replace_fd(new_fd, file, o_flags); |
| 1204 | if (error) |
| 1205 | return error; |
Kees Cook | 6659061 | 2020-06-10 08:20:05 -0700 | [diff] [blame] | 1206 | __receive_sock(file); |
Kees Cook | deefa7f | 2020-06-10 20:47:45 -0700 | [diff] [blame] | 1207 | return new_fd; |
Kees Cook | 6659061 | 2020-06-10 08:20:05 -0700 | [diff] [blame] | 1208 | } |
| 1209 | |
Xie Yongji | 9c93005 | 2021-08-31 18:36:24 +0800 | [diff] [blame] | 1210 | int receive_fd(struct file *file, unsigned int o_flags) |
| 1211 | { |
| 1212 | return __receive_fd(file, NULL, o_flags); |
| 1213 | } |
| 1214 | EXPORT_SYMBOL_GPL(receive_fd); |
| 1215 | |
Dominik Brodowski | c724832 | 2018-03-11 11:34:40 +0100 | [diff] [blame] | 1216 | static int ksys_dup3(unsigned int oldfd, unsigned int newfd, int flags) |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1217 | { |
| 1218 | int err = -EBADF; |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 1219 | struct file *file; |
| 1220 | struct files_struct *files = current->files; |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1221 | |
| 1222 | if ((flags & ~O_CLOEXEC) != 0) |
| 1223 | return -EINVAL; |
| 1224 | |
Richard W.M. Jones | aed9764 | 2012-10-09 15:27:43 +0100 | [diff] [blame] | 1225 | if (unlikely(oldfd == newfd)) |
| 1226 | return -EINVAL; |
| 1227 | |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1228 | if (newfd >= rlimit(RLIMIT_NOFILE)) |
Al Viro | 08f05c4 | 2012-10-31 03:37:48 +0000 | [diff] [blame] | 1229 | return -EBADF; |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1230 | |
| 1231 | spin_lock(&files->file_lock); |
| 1232 | err = expand_files(files, newfd); |
Eric W. Biederman | 120ce2b | 2020-11-20 17:14:25 -0600 | [diff] [blame] | 1233 | file = files_lookup_fd_locked(files, oldfd); |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1234 | if (unlikely(!file)) |
| 1235 | goto Ebadf; |
| 1236 | if (unlikely(err < 0)) { |
| 1237 | if (err == -EMFILE) |
| 1238 | goto Ebadf; |
| 1239 | goto out_unlock; |
| 1240 | } |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 1241 | return do_dup2(files, file, newfd, flags); |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1242 | |
| 1243 | Ebadf: |
| 1244 | err = -EBADF; |
| 1245 | out_unlock: |
| 1246 | spin_unlock(&files->file_lock); |
| 1247 | return err; |
| 1248 | } |
| 1249 | |
Dominik Brodowski | c724832 | 2018-03-11 11:34:40 +0100 | [diff] [blame] | 1250 | SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags) |
| 1251 | { |
| 1252 | return ksys_dup3(oldfd, newfd, flags); |
| 1253 | } |
| 1254 | |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1255 | SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd) |
| 1256 | { |
| 1257 | if (unlikely(newfd == oldfd)) { /* corner case */ |
| 1258 | struct files_struct *files = current->files; |
| 1259 | int retval = oldfd; |
| 1260 | |
| 1261 | rcu_read_lock(); |
Eric W. Biederman | f36c294 | 2020-11-20 17:14:26 -0600 | [diff] [blame] | 1262 | if (!files_lookup_fd_rcu(files, oldfd)) |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1263 | retval = -EBADF; |
| 1264 | rcu_read_unlock(); |
| 1265 | return retval; |
| 1266 | } |
Dominik Brodowski | c724832 | 2018-03-11 11:34:40 +0100 | [diff] [blame] | 1267 | return ksys_dup3(oldfd, newfd, 0); |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1268 | } |
| 1269 | |
Christoph Hellwig | bc1cd99 | 2020-07-14 08:58:49 +0200 | [diff] [blame] | 1270 | SYSCALL_DEFINE1(dup, unsigned int, fildes) |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1271 | { |
| 1272 | int ret = -EBADF; |
| 1273 | struct file *file = fget_raw(fildes); |
| 1274 | |
| 1275 | if (file) { |
Yann Droneaud | 8d10a03 | 2014-12-10 15:45:44 -0800 | [diff] [blame] | 1276 | ret = get_unused_fd_flags(0); |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1277 | if (ret >= 0) |
| 1278 | fd_install(ret, file); |
| 1279 | else |
| 1280 | fput(file); |
| 1281 | } |
| 1282 | return ret; |
| 1283 | } |
| 1284 | |
| 1285 | int f_dupfd(unsigned int from, struct file *file, unsigned flags) |
| 1286 | { |
Eric W. Biederman | e06b53c | 2020-11-20 17:14:36 -0600 | [diff] [blame] | 1287 | unsigned long nofile = rlimit(RLIMIT_NOFILE); |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1288 | int err; |
Eric W. Biederman | e06b53c | 2020-11-20 17:14:36 -0600 | [diff] [blame] | 1289 | if (from >= nofile) |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1290 | return -EINVAL; |
Eric W. Biederman | e06b53c | 2020-11-20 17:14:36 -0600 | [diff] [blame] | 1291 | err = alloc_fd(from, nofile, flags); |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 1292 | if (err >= 0) { |
| 1293 | get_file(file); |
| 1294 | fd_install(err, file); |
| 1295 | } |
| 1296 | return err; |
| 1297 | } |
Al Viro | c3c073f | 2012-08-21 22:32:06 -0400 | [diff] [blame] | 1298 | |
| 1299 | int iterate_fd(struct files_struct *files, unsigned n, |
| 1300 | int (*f)(const void *, struct file *, unsigned), |
| 1301 | const void *p) |
| 1302 | { |
| 1303 | struct fdtable *fdt; |
Al Viro | c3c073f | 2012-08-21 22:32:06 -0400 | [diff] [blame] | 1304 | int res = 0; |
| 1305 | if (!files) |
| 1306 | return 0; |
| 1307 | spin_lock(&files->file_lock); |
Al Viro | a77cfcb | 2012-11-29 22:57:33 -0500 | [diff] [blame] | 1308 | for (fdt = files_fdtable(files); n < fdt->max_fds; n++) { |
| 1309 | struct file *file; |
| 1310 | file = rcu_dereference_check_fdtable(files, fdt->fd[n]); |
| 1311 | if (!file) |
| 1312 | continue; |
| 1313 | res = f(p, file, n); |
| 1314 | if (res) |
| 1315 | break; |
Al Viro | c3c073f | 2012-08-21 22:32:06 -0400 | [diff] [blame] | 1316 | } |
| 1317 | spin_unlock(&files->file_lock); |
| 1318 | return res; |
| 1319 | } |
| 1320 | EXPORT_SYMBOL(iterate_fd); |