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> |
| 13 | #include <linux/mm.h> |
Ingo Molnar | 3f07c01 | 2017-02-08 18:51:30 +0100 | [diff] [blame] | 14 | #include <linux/sched/signal.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 15 | #include <linux/slab.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 16 | #include <linux/file.h> |
Al Viro | 9f3acc3 | 2008-04-24 07:44:08 -0400 | [diff] [blame] | 17 | #include <linux/fdtable.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 18 | #include <linux/bitops.h> |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 19 | #include <linux/spinlock.h> |
| 20 | #include <linux/rcupdate.h> |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 21 | |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 22 | unsigned int sysctl_nr_open __read_mostly = 1024*1024; |
| 23 | unsigned int sysctl_nr_open_min = BITS_PER_LONG; |
Rasmus Villemoes | 752343b | 2015-10-29 12:01:41 +0100 | [diff] [blame] | 24 | /* our min() is unusable in constant expressions ;-/ */ |
| 25 | #define __const_min(x, y) ((x) < (y) ? (x) : (y)) |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 26 | unsigned int sysctl_nr_open_max = |
| 27 | __const_min(INT_MAX, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG; |
Eric Dumazet | 9cfe015 | 2008-02-06 01:37:16 -0800 | [diff] [blame] | 28 | |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 29 | static void __free_fdtable(struct fdtable *fdt) |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 30 | { |
Al Viro | f6c0a19 | 2014-04-23 10:18:46 -0400 | [diff] [blame] | 31 | kvfree(fdt->fd); |
| 32 | kvfree(fdt->open_fds); |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 33 | kfree(fdt); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 34 | } |
| 35 | |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 36 | static void free_fdtable_rcu(struct rcu_head *rcu) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 37 | { |
Al Viro | ac3e3c5 | 2013-04-28 21:42:33 -0400 | [diff] [blame] | 38 | __free_fdtable(container_of(rcu, struct fdtable, rcu)); |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 39 | } |
| 40 | |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 41 | #define BITBIT_NR(nr) BITS_TO_LONGS(BITS_TO_LONGS(nr)) |
| 42 | #define BITBIT_SIZE(nr) (BITBIT_NR(nr) * sizeof(long)) |
| 43 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 44 | /* |
Eric Biggers | ea5c58e | 2015-11-06 00:32:04 -0600 | [diff] [blame] | 45 | * Copy 'count' fd bits from the old table to the new table and clear the extra |
| 46 | * space if any. This does not copy the file pointers. Called with the files |
| 47 | * spinlock held for write. |
| 48 | */ |
| 49 | static void copy_fd_bitmaps(struct fdtable *nfdt, struct fdtable *ofdt, |
| 50 | unsigned int count) |
| 51 | { |
| 52 | unsigned int cpy, set; |
| 53 | |
| 54 | cpy = count / BITS_PER_BYTE; |
| 55 | set = (nfdt->max_fds - count) / BITS_PER_BYTE; |
| 56 | memcpy(nfdt->open_fds, ofdt->open_fds, cpy); |
| 57 | memset((char *)nfdt->open_fds + cpy, 0, set); |
| 58 | memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy); |
| 59 | memset((char *)nfdt->close_on_exec + cpy, 0, set); |
| 60 | |
| 61 | cpy = BITBIT_SIZE(count); |
| 62 | set = BITBIT_SIZE(nfdt->max_fds) - cpy; |
| 63 | memcpy(nfdt->full_fds_bits, ofdt->full_fds_bits, cpy); |
| 64 | memset((char *)nfdt->full_fds_bits + cpy, 0, set); |
| 65 | } |
| 66 | |
| 67 | /* |
| 68 | * Copy all file descriptors from the old table to the new, expanded table and |
| 69 | * clear the extra space. Called with the files spinlock held for write. |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 70 | */ |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 71 | static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 72 | { |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 73 | unsigned int cpy, set; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 74 | |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 75 | BUG_ON(nfdt->max_fds < ofdt->max_fds); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 76 | |
| 77 | cpy = ofdt->max_fds * sizeof(struct file *); |
| 78 | set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *); |
| 79 | memcpy(nfdt->fd, ofdt->fd, cpy); |
Eric Biggers | ea5c58e | 2015-11-06 00:32:04 -0600 | [diff] [blame] | 80 | memset((char *)nfdt->fd + cpy, 0, set); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 81 | |
Eric Biggers | ea5c58e | 2015-11-06 00:32:04 -0600 | [diff] [blame] | 82 | copy_fd_bitmaps(nfdt, ofdt, ofdt->max_fds); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 83 | } |
| 84 | |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 85 | static struct fdtable * alloc_fdtable(unsigned int nr) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 86 | { |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 87 | struct fdtable *fdt; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 88 | void *data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 89 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 90 | /* |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 91 | * Figure out how many fds we actually want to support in this fdtable. |
| 92 | * Allocation steps are keyed to the size of the fdarray, since it |
| 93 | * grows far faster than any of the other dynamic data. We try to fit |
| 94 | * the fdarray into comfortable page-tuned chunks: starting at 1024B |
| 95 | * and growing in powers of two from there on. |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 96 | */ |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 97 | nr /= (1024 / sizeof(struct file *)); |
| 98 | nr = roundup_pow_of_two(nr + 1); |
| 99 | nr *= (1024 / sizeof(struct file *)); |
Al Viro | 5c598b3 | 2008-04-27 20:04:15 -0400 | [diff] [blame] | 100 | /* |
| 101 | * Note that this can drive nr *below* what we had passed if sysctl_nr_open |
| 102 | * had been set lower between the check in expand_files() and here. Deal |
| 103 | * with that in caller, it's cheaper that way. |
| 104 | * |
| 105 | * We make sure that nr remains a multiple of BITS_PER_LONG - otherwise |
| 106 | * bitmaps handling below becomes unpleasant, to put it mildly... |
| 107 | */ |
| 108 | if (unlikely(nr > sysctl_nr_open)) |
| 109 | nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1; |
Vadim Lobanov | bbea9f6 | 2006-12-10 02:21:12 -0800 | [diff] [blame] | 110 | |
Vladimir Davydov | 5d09705 | 2016-01-14 15:18:21 -0800 | [diff] [blame] | 111 | fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL_ACCOUNT); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 112 | if (!fdt) |
Vadim Lobanov | bbea9f6 | 2006-12-10 02:21:12 -0800 | [diff] [blame] | 113 | goto out; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 114 | fdt->max_fds = nr; |
Michal Hocko | c823bd9 | 2017-07-06 15:36:19 -0700 | [diff] [blame] | 115 | data = kvmalloc_array(nr, sizeof(struct file *), GFP_KERNEL_ACCOUNT); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 116 | if (!data) |
| 117 | goto out_fdt; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 118 | fdt->fd = data; |
| 119 | |
Michal Hocko | c823bd9 | 2017-07-06 15:36:19 -0700 | [diff] [blame] | 120 | data = kvmalloc(max_t(size_t, |
| 121 | 2 * nr / BITS_PER_BYTE + BITBIT_SIZE(nr), L1_CACHE_BYTES), |
| 122 | GFP_KERNEL_ACCOUNT); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 123 | if (!data) |
| 124 | goto out_arr; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 125 | fdt->open_fds = data; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 126 | data += nr / BITS_PER_BYTE; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 127 | fdt->close_on_exec = data; |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 128 | data += nr / BITS_PER_BYTE; |
| 129 | fdt->full_fds_bits = data; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 130 | |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 131 | return fdt; |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 132 | |
| 133 | out_arr: |
Al Viro | f6c0a19 | 2014-04-23 10:18:46 -0400 | [diff] [blame] | 134 | kvfree(fdt->fd); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 135 | out_fdt: |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 136 | kfree(fdt); |
Vadim Lobanov | 5466b45 | 2006-12-10 02:21:22 -0800 | [diff] [blame] | 137 | out: |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 138 | return NULL; |
| 139 | } |
| 140 | |
| 141 | /* |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 142 | * Expand the file descriptor table. |
| 143 | * This function will allocate a new fdtable and both fd array and fdset, of |
| 144 | * the given size. |
| 145 | * Return <0 error code on error; 1 on successful completion. |
| 146 | * 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] | 147 | */ |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 148 | static int expand_fdtable(struct files_struct *files, unsigned int nr) |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 149 | __releases(files->file_lock) |
| 150 | __acquires(files->file_lock) |
| 151 | { |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 152 | struct fdtable *new_fdt, *cur_fdt; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 153 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 154 | spin_unlock(&files->file_lock); |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 155 | new_fdt = alloc_fdtable(nr); |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 156 | |
| 157 | /* make sure all __fd_install() have seen resize_in_progress |
| 158 | * or have finished their rcu_read_lock_sched() section. |
| 159 | */ |
| 160 | if (atomic_read(&files->count) > 1) |
| 161 | synchronize_sched(); |
| 162 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 163 | spin_lock(&files->file_lock); |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 164 | if (!new_fdt) |
| 165 | return -ENOMEM; |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 166 | /* |
Al Viro | 5c598b3 | 2008-04-27 20:04:15 -0400 | [diff] [blame] | 167 | * extremely unlikely race - sysctl_nr_open decreased between the check in |
| 168 | * caller and alloc_fdtable(). Cheaper to catch it here... |
| 169 | */ |
| 170 | if (unlikely(new_fdt->max_fds <= nr)) { |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 171 | __free_fdtable(new_fdt); |
Al Viro | 5c598b3 | 2008-04-27 20:04:15 -0400 | [diff] [blame] | 172 | return -EMFILE; |
| 173 | } |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 174 | cur_fdt = files_fdtable(files); |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 175 | BUG_ON(nr < cur_fdt->max_fds); |
| 176 | copy_fdtable(new_fdt, cur_fdt); |
| 177 | rcu_assign_pointer(files->fdt, new_fdt); |
| 178 | if (cur_fdt != &files->fdtab) |
| 179 | call_rcu(&cur_fdt->rcu, free_fdtable_rcu); |
| 180 | /* coupled with smp_rmb() in __fd_install() */ |
| 181 | smp_wmb(); |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 182 | return 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 183 | } |
| 184 | |
| 185 | /* |
| 186 | * Expand files. |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 187 | * This function will expand the file structures, if the requested size exceeds |
| 188 | * the current capacity and there is room for expansion. |
| 189 | * Return <0 error code on error; 0 when nothing done; 1 when files were |
| 190 | * expanded and execution may have blocked. |
| 191 | * 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] | 192 | */ |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 193 | static int expand_files(struct files_struct *files, unsigned int nr) |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 194 | __releases(files->file_lock) |
| 195 | __acquires(files->file_lock) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 196 | { |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 197 | struct fdtable *fdt; |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 198 | int expanded = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 199 | |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 200 | repeat: |
Dipankar Sarma | badf166 | 2005-09-09 13:04:10 -0700 | [diff] [blame] | 201 | fdt = files_fdtable(files); |
Al Viro | 4e1e018 | 2008-07-26 16:01:20 -0400 | [diff] [blame] | 202 | |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 203 | /* Do we need to expand? */ |
Vadim Lobanov | bbea9f6 | 2006-12-10 02:21:12 -0800 | [diff] [blame] | 204 | if (nr < fdt->max_fds) |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 205 | return expanded; |
Al Viro | 4e1e018 | 2008-07-26 16:01:20 -0400 | [diff] [blame] | 206 | |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 207 | /* Can we expand? */ |
Eric Dumazet | 9cfe015 | 2008-02-06 01:37:16 -0800 | [diff] [blame] | 208 | if (nr >= sysctl_nr_open) |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 209 | return -EMFILE; |
| 210 | |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 211 | if (unlikely(files->resize_in_progress)) { |
| 212 | spin_unlock(&files->file_lock); |
| 213 | expanded = 1; |
| 214 | wait_event(files->resize_wait, !files->resize_in_progress); |
| 215 | spin_lock(&files->file_lock); |
| 216 | goto repeat; |
| 217 | } |
| 218 | |
Vadim Lobanov | 74d392a | 2006-09-29 02:01:43 -0700 | [diff] [blame] | 219 | /* All good, so we try */ |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 220 | files->resize_in_progress = true; |
| 221 | expanded = expand_fdtable(files, nr); |
| 222 | files->resize_in_progress = false; |
| 223 | |
| 224 | wake_up_all(&files->resize_wait); |
| 225 | return expanded; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 226 | } |
Dipankar Sarma | ab2af1f | 2005-09-09 13:04:13 -0700 | [diff] [blame] | 227 | |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 228 | 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] | 229 | { |
| 230 | __set_bit(fd, fdt->close_on_exec); |
| 231 | } |
| 232 | |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 233 | 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] | 234 | { |
Linus Torvalds | fc90888 | 2015-10-31 16:06:40 -0700 | [diff] [blame] | 235 | if (test_bit(fd, fdt->close_on_exec)) |
| 236 | __clear_bit(fd, fdt->close_on_exec); |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 237 | } |
| 238 | |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 239 | static inline void __set_open_fd(unsigned int fd, struct fdtable *fdt) |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 240 | { |
| 241 | __set_bit(fd, fdt->open_fds); |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 242 | fd /= BITS_PER_LONG; |
| 243 | if (!~fdt->open_fds[fd]) |
| 244 | __set_bit(fd, fdt->full_fds_bits); |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 245 | } |
| 246 | |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 247 | static inline void __clear_open_fd(unsigned int fd, struct fdtable *fdt) |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 248 | { |
| 249 | __clear_bit(fd, fdt->open_fds); |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 250 | __clear_bit(fd / BITS_PER_LONG, fdt->full_fds_bits); |
Al Viro | b8318b0 | 2012-08-21 20:09:42 -0400 | [diff] [blame] | 251 | } |
| 252 | |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 253 | static unsigned int count_open_files(struct fdtable *fdt) |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 254 | { |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 255 | unsigned int size = fdt->max_fds; |
| 256 | unsigned int i; |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 257 | |
| 258 | /* Find the last open fd */ |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 259 | for (i = size / BITS_PER_LONG; i > 0; ) { |
| 260 | if (fdt->open_fds[--i]) |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 261 | break; |
| 262 | } |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 263 | i = (i + 1) * BITS_PER_LONG; |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 264 | return i; |
| 265 | } |
| 266 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 267 | /* |
| 268 | * Allocate a new files structure and copy contents from the |
| 269 | * passed in files structure. |
| 270 | * errorp will be valid only when the returned files_struct is NULL. |
| 271 | */ |
| 272 | struct files_struct *dup_fd(struct files_struct *oldf, int *errorp) |
| 273 | { |
| 274 | struct files_struct *newf; |
| 275 | struct file **old_fds, **new_fds; |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 276 | unsigned int open_files, i; |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 277 | struct fdtable *old_fdt, *new_fdt; |
| 278 | |
| 279 | *errorp = -ENOMEM; |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 280 | newf = kmem_cache_alloc(files_cachep, GFP_KERNEL); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 281 | if (!newf) |
| 282 | goto out; |
| 283 | |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 284 | atomic_set(&newf->count, 1); |
| 285 | |
| 286 | spin_lock_init(&newf->file_lock); |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 287 | newf->resize_in_progress = false; |
| 288 | init_waitqueue_head(&newf->resize_wait); |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 289 | newf->next_fd = 0; |
| 290 | new_fdt = &newf->fdtab; |
| 291 | new_fdt->max_fds = NR_OPEN_DEFAULT; |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 292 | new_fdt->close_on_exec = newf->close_on_exec_init; |
| 293 | new_fdt->open_fds = newf->open_fds_init; |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 294 | new_fdt->full_fds_bits = newf->full_fds_bits_init; |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 295 | new_fdt->fd = &newf->fd_array[0]; |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 296 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 297 | spin_lock(&oldf->file_lock); |
| 298 | old_fdt = files_fdtable(oldf); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 299 | open_files = count_open_files(old_fdt); |
| 300 | |
| 301 | /* |
| 302 | * 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] | 303 | */ |
Al Viro | adbecb1 | 2008-05-08 21:19:42 -0400 | [diff] [blame] | 304 | while (unlikely(open_files > new_fdt->max_fds)) { |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 305 | spin_unlock(&oldf->file_lock); |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 306 | |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 307 | if (new_fdt != &newf->fdtab) |
| 308 | __free_fdtable(new_fdt); |
Al Viro | adbecb1 | 2008-05-08 21:19:42 -0400 | [diff] [blame] | 309 | |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 310 | new_fdt = alloc_fdtable(open_files - 1); |
| 311 | if (!new_fdt) { |
| 312 | *errorp = -ENOMEM; |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 313 | goto out_release; |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 314 | } |
| 315 | |
| 316 | /* beyond sysctl_nr_open; nothing to do */ |
| 317 | if (unlikely(new_fdt->max_fds < open_files)) { |
Changli Gao | a892e2d | 2010-08-10 18:01:35 -0700 | [diff] [blame] | 318 | __free_fdtable(new_fdt); |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 319 | *errorp = -EMFILE; |
| 320 | goto out_release; |
| 321 | } |
Al Viro | 9dec3c4 | 2008-05-08 21:02:45 -0400 | [diff] [blame] | 322 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 323 | /* |
| 324 | * Reacquire the oldf lock and a pointer to its fd table |
| 325 | * who knows it may have a new bigger fd table. We need |
| 326 | * the latest pointer. |
| 327 | */ |
| 328 | spin_lock(&oldf->file_lock); |
| 329 | old_fdt = files_fdtable(oldf); |
Al Viro | adbecb1 | 2008-05-08 21:19:42 -0400 | [diff] [blame] | 330 | open_files = count_open_files(old_fdt); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 331 | } |
| 332 | |
Eric Biggers | ea5c58e | 2015-11-06 00:32:04 -0600 | [diff] [blame] | 333 | copy_fd_bitmaps(new_fdt, old_fdt, open_files); |
| 334 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 335 | old_fds = old_fdt->fd; |
| 336 | new_fds = new_fdt->fd; |
| 337 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 338 | for (i = open_files; i != 0; i--) { |
| 339 | struct file *f = *old_fds++; |
| 340 | if (f) { |
| 341 | get_file(f); |
| 342 | } else { |
| 343 | /* |
| 344 | * The fd may be claimed in the fd bitmap but not yet |
| 345 | * instantiated in the files array if a sibling thread |
| 346 | * is partway through open(). So make sure that this |
| 347 | * fd is available to the new process. |
| 348 | */ |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 349 | __clear_open_fd(open_files - i, new_fdt); |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 350 | } |
| 351 | rcu_assign_pointer(*new_fds++, f); |
| 352 | } |
| 353 | spin_unlock(&oldf->file_lock); |
| 354 | |
Eric Biggers | ea5c58e | 2015-11-06 00:32:04 -0600 | [diff] [blame] | 355 | /* clear the remainder */ |
| 356 | 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] | 357 | |
Al Viro | afbec7f | 2008-05-08 21:11:17 -0400 | [diff] [blame] | 358 | rcu_assign_pointer(newf->fdt, new_fdt); |
| 359 | |
Al Viro | 02afc626 | 2008-05-08 19:42:56 -0400 | [diff] [blame] | 360 | return newf; |
| 361 | |
| 362 | out_release: |
| 363 | kmem_cache_free(files_cachep, newf); |
| 364 | out: |
| 365 | return NULL; |
| 366 | } |
| 367 | |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 368 | static struct fdtable *close_files(struct files_struct * files) |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 369 | { |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 370 | /* |
| 371 | * It is safe to dereference the fd table without RCU or |
| 372 | * ->file_lock because this is the last reference to the |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 373 | * files structure. |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 374 | */ |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 375 | struct fdtable *fdt = rcu_dereference_raw(files->fdt); |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 376 | unsigned int i, j = 0; |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 377 | |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 378 | for (;;) { |
| 379 | unsigned long set; |
| 380 | i = j * BITS_PER_LONG; |
| 381 | if (i >= fdt->max_fds) |
| 382 | break; |
| 383 | set = fdt->open_fds[j++]; |
| 384 | while (set) { |
| 385 | if (set & 1) { |
| 386 | struct file * file = xchg(&fdt->fd[i], NULL); |
| 387 | if (file) { |
| 388 | filp_close(file, files); |
Paul E. McKenney | 388a4c8 | 2017-10-24 08:39:34 -0700 | [diff] [blame] | 389 | cond_resched(); |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 390 | } |
| 391 | } |
| 392 | i++; |
| 393 | set >>= 1; |
| 394 | } |
| 395 | } |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 396 | |
| 397 | return fdt; |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 398 | } |
| 399 | |
| 400 | struct files_struct *get_files_struct(struct task_struct *task) |
| 401 | { |
| 402 | struct files_struct *files; |
| 403 | |
| 404 | task_lock(task); |
| 405 | files = task->files; |
| 406 | if (files) |
| 407 | atomic_inc(&files->count); |
| 408 | task_unlock(task); |
| 409 | |
| 410 | return files; |
| 411 | } |
| 412 | |
| 413 | void put_files_struct(struct files_struct *files) |
| 414 | { |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 415 | if (atomic_dec_and_test(&files->count)) { |
Oleg Nesterov | ce08b62 | 2014-01-11 19:19:53 +0100 | [diff] [blame] | 416 | struct fdtable *fdt = close_files(files); |
| 417 | |
Al Viro | b9e02af | 2012-08-15 20:00:58 -0400 | [diff] [blame] | 418 | /* free the arrays if they are not embedded */ |
| 419 | if (fdt != &files->fdtab) |
| 420 | __free_fdtable(fdt); |
| 421 | kmem_cache_free(files_cachep, files); |
Al Viro | 7cf4dc3 | 2012-08-15 19:56:12 -0400 | [diff] [blame] | 422 | } |
| 423 | } |
| 424 | |
| 425 | void reset_files_struct(struct files_struct *files) |
| 426 | { |
| 427 | struct task_struct *tsk = current; |
| 428 | struct files_struct *old; |
| 429 | |
| 430 | old = tsk->files; |
| 431 | task_lock(tsk); |
| 432 | tsk->files = files; |
| 433 | task_unlock(tsk); |
| 434 | put_files_struct(old); |
| 435 | } |
| 436 | |
| 437 | void exit_files(struct task_struct *tsk) |
| 438 | { |
| 439 | struct files_struct * files = tsk->files; |
| 440 | |
| 441 | if (files) { |
| 442 | task_lock(tsk); |
| 443 | tsk->files = NULL; |
| 444 | task_unlock(tsk); |
| 445 | put_files_struct(files); |
| 446 | } |
| 447 | } |
| 448 | |
Al Viro | f52111b | 2008-05-08 18:19:16 -0400 | [diff] [blame] | 449 | struct files_struct init_files = { |
| 450 | .count = ATOMIC_INIT(1), |
| 451 | .fdt = &init_files.fdtab, |
| 452 | .fdtab = { |
| 453 | .max_fds = NR_OPEN_DEFAULT, |
| 454 | .fd = &init_files.fd_array[0], |
David Howells | 1fd36ad | 2012-02-16 17:49:54 +0000 | [diff] [blame] | 455 | .close_on_exec = init_files.close_on_exec_init, |
| 456 | .open_fds = init_files.open_fds_init, |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 457 | .full_fds_bits = init_files.full_fds_bits_init, |
Al Viro | f52111b | 2008-05-08 18:19:16 -0400 | [diff] [blame] | 458 | }, |
Thomas Gleixner | eece09e | 2011-07-17 21:25:03 +0200 | [diff] [blame] | 459 | .file_lock = __SPIN_LOCK_UNLOCKED(init_files.file_lock), |
Al Viro | f52111b | 2008-05-08 18:19:16 -0400 | [diff] [blame] | 460 | }; |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 461 | |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 462 | static unsigned int find_next_fd(struct fdtable *fdt, unsigned int start) |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 463 | { |
Alexey Dobriyan | 9b80a18 | 2016-09-02 00:38:52 +0300 | [diff] [blame] | 464 | unsigned int maxfd = fdt->max_fds; |
| 465 | unsigned int maxbit = maxfd / BITS_PER_LONG; |
| 466 | unsigned int bitbit = start / BITS_PER_LONG; |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 467 | |
| 468 | bitbit = find_next_zero_bit(fdt->full_fds_bits, maxbit, bitbit) * BITS_PER_LONG; |
| 469 | if (bitbit > maxfd) |
| 470 | return maxfd; |
| 471 | if (bitbit > start) |
| 472 | start = bitbit; |
| 473 | return find_next_zero_bit(fdt->open_fds, maxfd, start); |
| 474 | } |
| 475 | |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 476 | /* |
| 477 | * allocate a file descriptor, mark it busy. |
| 478 | */ |
Al Viro | dcfadfa | 2012-08-12 17:27:30 -0400 | [diff] [blame] | 479 | int __alloc_fd(struct files_struct *files, |
| 480 | unsigned start, unsigned end, unsigned flags) |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 481 | { |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 482 | unsigned int fd; |
| 483 | int error; |
| 484 | struct fdtable *fdt; |
| 485 | |
| 486 | spin_lock(&files->file_lock); |
| 487 | repeat: |
| 488 | fdt = files_fdtable(files); |
| 489 | fd = start; |
| 490 | if (fd < files->next_fd) |
| 491 | fd = files->next_fd; |
| 492 | |
| 493 | if (fd < fdt->max_fds) |
Linus Torvalds | f3f86e3 | 2015-10-30 16:53:57 -0700 | [diff] [blame] | 494 | fd = find_next_fd(fdt, fd); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 495 | |
Al Viro | f33ff99 | 2012-08-12 16:17:59 -0400 | [diff] [blame] | 496 | /* |
| 497 | * N.B. For clone tasks sharing a files structure, this test |
| 498 | * will limit the total number of files that can be opened. |
| 499 | */ |
| 500 | error = -EMFILE; |
| 501 | if (fd >= end) |
| 502 | goto out; |
| 503 | |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 504 | error = expand_files(files, fd); |
| 505 | if (error < 0) |
| 506 | goto out; |
| 507 | |
| 508 | /* |
| 509 | * If we needed to expand the fs array we |
| 510 | * might have blocked - try again. |
| 511 | */ |
| 512 | if (error) |
| 513 | goto repeat; |
| 514 | |
| 515 | if (start <= files->next_fd) |
| 516 | files->next_fd = fd + 1; |
| 517 | |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 518 | __set_open_fd(fd, fdt); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 519 | if (flags & O_CLOEXEC) |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 520 | __set_close_on_exec(fd, fdt); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 521 | else |
David Howells | 1dce27c | 2012-02-16 17:49:42 +0000 | [diff] [blame] | 522 | __clear_close_on_exec(fd, fdt); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 523 | error = fd; |
| 524 | #if 1 |
| 525 | /* Sanity check */ |
Paul E. McKenney | add1f09 | 2014-02-12 12:51:09 -0800 | [diff] [blame] | 526 | if (rcu_access_pointer(fdt->fd[fd]) != NULL) { |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 527 | printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd); |
| 528 | rcu_assign_pointer(fdt->fd[fd], NULL); |
| 529 | } |
| 530 | #endif |
| 531 | |
| 532 | out: |
| 533 | spin_unlock(&files->file_lock); |
| 534 | return error; |
| 535 | } |
| 536 | |
Al Viro | ad47bd7 | 2012-08-21 20:11:34 -0400 | [diff] [blame] | 537 | static int alloc_fd(unsigned start, unsigned flags) |
Al Viro | dcfadfa | 2012-08-12 17:27:30 -0400 | [diff] [blame] | 538 | { |
| 539 | return __alloc_fd(current->files, start, rlimit(RLIMIT_NOFILE), flags); |
| 540 | } |
| 541 | |
Al Viro | 1a7bd22 | 2012-08-12 17:18:05 -0400 | [diff] [blame] | 542 | int get_unused_fd_flags(unsigned flags) |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 543 | { |
Al Viro | dcfadfa | 2012-08-12 17:27:30 -0400 | [diff] [blame] | 544 | return __alloc_fd(current->files, 0, rlimit(RLIMIT_NOFILE), flags); |
Al Viro | 1027abe | 2008-07-30 04:13:04 -0400 | [diff] [blame] | 545 | } |
Al Viro | 1a7bd22 | 2012-08-12 17:18:05 -0400 | [diff] [blame] | 546 | EXPORT_SYMBOL(get_unused_fd_flags); |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 547 | |
| 548 | static void __put_unused_fd(struct files_struct *files, unsigned int fd) |
| 549 | { |
| 550 | struct fdtable *fdt = files_fdtable(files); |
| 551 | __clear_open_fd(fd, fdt); |
| 552 | if (fd < files->next_fd) |
| 553 | files->next_fd = fd; |
| 554 | } |
| 555 | |
| 556 | void put_unused_fd(unsigned int fd) |
| 557 | { |
| 558 | struct files_struct *files = current->files; |
| 559 | spin_lock(&files->file_lock); |
| 560 | __put_unused_fd(files, fd); |
| 561 | spin_unlock(&files->file_lock); |
| 562 | } |
| 563 | |
| 564 | EXPORT_SYMBOL(put_unused_fd); |
| 565 | |
| 566 | /* |
| 567 | * Install a file pointer in the fd array. |
| 568 | * |
| 569 | * The VFS is full of places where we drop the files lock between |
| 570 | * setting the open_fds bitmap and installing the file in the file |
| 571 | * array. At any such point, we are vulnerable to a dup2() race |
| 572 | * installing a file in the array before us. We need to detect this and |
| 573 | * fput() the struct file we are about to overwrite in this case. |
| 574 | * |
| 575 | * It should never happen - if we allow dup2() do it, _really_ bad things |
| 576 | * will follow. |
Al Viro | f869e8a | 2012-08-15 21:06:33 -0400 | [diff] [blame] | 577 | * |
| 578 | * NOTE: __fd_install() variant is really, really low-level; don't |
| 579 | * use it unless you are forced to by truly lousy API shoved down |
| 580 | * your throat. 'files' *MUST* be either current->files or obtained |
| 581 | * by get_files_struct(current) done by whoever had given it to you, |
| 582 | * or really bad things will happen. Normally you want to use |
| 583 | * fd_install() instead. |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 584 | */ |
| 585 | |
Al Viro | f869e8a | 2012-08-15 21:06:33 -0400 | [diff] [blame] | 586 | void __fd_install(struct files_struct *files, unsigned int fd, |
| 587 | struct file *file) |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 588 | { |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 589 | struct fdtable *fdt; |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 590 | |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 591 | rcu_read_lock_sched(); |
| 592 | |
Mateusz Guzik | c02b1a9 | 2017-10-03 12:58:15 +0200 | [diff] [blame] | 593 | if (unlikely(files->resize_in_progress)) { |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 594 | rcu_read_unlock_sched(); |
Mateusz Guzik | c02b1a9 | 2017-10-03 12:58:15 +0200 | [diff] [blame] | 595 | spin_lock(&files->file_lock); |
| 596 | fdt = files_fdtable(files); |
| 597 | BUG_ON(fdt->fd[fd] != NULL); |
| 598 | rcu_assign_pointer(fdt->fd[fd], file); |
| 599 | spin_unlock(&files->file_lock); |
| 600 | return; |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 601 | } |
| 602 | /* coupled with smp_wmb() in expand_fdtable() */ |
| 603 | smp_rmb(); |
| 604 | fdt = rcu_dereference_sched(files->fdt); |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 605 | BUG_ON(fdt->fd[fd] != NULL); |
| 606 | rcu_assign_pointer(fdt->fd[fd], file); |
Eric Dumazet | 8a81252 | 2015-06-30 15:54:08 +0200 | [diff] [blame] | 607 | rcu_read_unlock_sched(); |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 608 | } |
| 609 | |
Al Viro | f869e8a | 2012-08-15 21:06:33 -0400 | [diff] [blame] | 610 | void fd_install(unsigned int fd, struct file *file) |
| 611 | { |
| 612 | __fd_install(current->files, fd, file); |
| 613 | } |
| 614 | |
Al Viro | 56007ca | 2012-08-15 21:03:26 -0400 | [diff] [blame] | 615 | EXPORT_SYMBOL(fd_install); |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 616 | |
Al Viro | 483ce1d | 2012-08-19 12:04:24 -0400 | [diff] [blame] | 617 | /* |
| 618 | * The same warnings as for __alloc_fd()/__fd_install() apply here... |
| 619 | */ |
| 620 | int __close_fd(struct files_struct *files, unsigned fd) |
| 621 | { |
| 622 | struct file *file; |
| 623 | struct fdtable *fdt; |
| 624 | |
| 625 | spin_lock(&files->file_lock); |
| 626 | fdt = files_fdtable(files); |
| 627 | if (fd >= fdt->max_fds) |
| 628 | goto out_unlock; |
| 629 | file = fdt->fd[fd]; |
| 630 | if (!file) |
| 631 | goto out_unlock; |
| 632 | rcu_assign_pointer(fdt->fd[fd], NULL); |
Al Viro | 483ce1d | 2012-08-19 12:04:24 -0400 | [diff] [blame] | 633 | __put_unused_fd(files, fd); |
| 634 | spin_unlock(&files->file_lock); |
| 635 | return filp_close(file, files); |
| 636 | |
| 637 | out_unlock: |
| 638 | spin_unlock(&files->file_lock); |
| 639 | return -EBADF; |
| 640 | } |
| 641 | |
Al Viro | 6a6d27d | 2012-08-21 09:56:33 -0400 | [diff] [blame] | 642 | void do_close_on_exec(struct files_struct *files) |
| 643 | { |
| 644 | unsigned i; |
| 645 | struct fdtable *fdt; |
| 646 | |
| 647 | /* exec unshares first */ |
Al Viro | 6a6d27d | 2012-08-21 09:56:33 -0400 | [diff] [blame] | 648 | spin_lock(&files->file_lock); |
| 649 | for (i = 0; ; i++) { |
| 650 | unsigned long set; |
| 651 | unsigned fd = i * BITS_PER_LONG; |
| 652 | fdt = files_fdtable(files); |
| 653 | if (fd >= fdt->max_fds) |
| 654 | break; |
| 655 | set = fdt->close_on_exec[i]; |
| 656 | if (!set) |
| 657 | continue; |
| 658 | fdt->close_on_exec[i] = 0; |
| 659 | for ( ; set ; fd++, set >>= 1) { |
| 660 | struct file *file; |
| 661 | if (!(set & 1)) |
| 662 | continue; |
| 663 | file = fdt->fd[fd]; |
| 664 | if (!file) |
| 665 | continue; |
| 666 | rcu_assign_pointer(fdt->fd[fd], NULL); |
| 667 | __put_unused_fd(files, fd); |
| 668 | spin_unlock(&files->file_lock); |
| 669 | filp_close(file, files); |
| 670 | cond_resched(); |
| 671 | spin_lock(&files->file_lock); |
| 672 | } |
| 673 | |
| 674 | } |
| 675 | spin_unlock(&files->file_lock); |
| 676 | } |
| 677 | |
Oleg Nesterov | 1deb46e | 2014-01-13 16:48:19 +0100 | [diff] [blame] | 678 | static struct file *__fget(unsigned int fd, fmode_t mask) |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 679 | { |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 680 | struct files_struct *files = current->files; |
Oleg Nesterov | 1deb46e | 2014-01-13 16:48:19 +0100 | [diff] [blame] | 681 | struct file *file; |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 682 | |
| 683 | rcu_read_lock(); |
Eric Dumazet | 5ba97d2 | 2015-06-29 17:10:30 +0200 | [diff] [blame] | 684 | loop: |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 685 | file = fcheck_files(files, fd); |
| 686 | if (file) { |
Eric Dumazet | 5ba97d2 | 2015-06-29 17:10:30 +0200 | [diff] [blame] | 687 | /* File object ref couldn't be taken. |
| 688 | * dup2() atomicity guarantee is the reason |
| 689 | * we loop to catch the new file (or NULL pointer) |
| 690 | */ |
| 691 | if (file->f_mode & mask) |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 692 | file = NULL; |
Eric Dumazet | 5ba97d2 | 2015-06-29 17:10:30 +0200 | [diff] [blame] | 693 | else if (!get_file_rcu(file)) |
| 694 | goto loop; |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 695 | } |
| 696 | rcu_read_unlock(); |
| 697 | |
| 698 | return file; |
| 699 | } |
| 700 | |
Oleg Nesterov | 1deb46e | 2014-01-13 16:48:19 +0100 | [diff] [blame] | 701 | struct file *fget(unsigned int fd) |
| 702 | { |
| 703 | return __fget(fd, FMODE_PATH); |
| 704 | } |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 705 | EXPORT_SYMBOL(fget); |
| 706 | |
| 707 | struct file *fget_raw(unsigned int fd) |
| 708 | { |
Oleg Nesterov | 1deb46e | 2014-01-13 16:48:19 +0100 | [diff] [blame] | 709 | return __fget(fd, 0); |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 710 | } |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 711 | EXPORT_SYMBOL(fget_raw); |
| 712 | |
| 713 | /* |
| 714 | * Lightweight file lookup - no refcnt increment if fd table isn't shared. |
| 715 | * |
| 716 | * You can use this instead of fget if you satisfy all of the following |
| 717 | * conditions: |
| 718 | * 1) You must call fput_light before exiting the syscall and returning control |
| 719 | * to userspace (i.e. you cannot remember the returned struct file * after |
| 720 | * returning to userspace). |
| 721 | * 2) You must not call filp_close on the returned struct file * in between |
| 722 | * calls to fget_light and fput_light. |
| 723 | * 3) You must not clone the current task in between the calls to fget_light |
| 724 | * and fput_light. |
| 725 | * |
| 726 | * The fput_needed flag returned by fget_light should be passed to the |
| 727 | * corresponding fput_light. |
| 728 | */ |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 729 | static unsigned long __fget_light(unsigned int fd, fmode_t mask) |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 730 | { |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 731 | struct files_struct *files = current->files; |
Oleg Nesterov | ad46183 | 2014-01-13 16:48:40 +0100 | [diff] [blame] | 732 | struct file *file; |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 733 | |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 734 | if (atomic_read(&files->count) == 1) { |
Oleg Nesterov | a8d4b83 | 2014-01-11 19:19:32 +0100 | [diff] [blame] | 735 | file = __fcheck_files(files, fd); |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 736 | if (!file || unlikely(file->f_mode & mask)) |
| 737 | return 0; |
| 738 | return (unsigned long)file; |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 739 | } else { |
Oleg Nesterov | e6ff9a9 | 2014-01-13 16:49:06 +0100 | [diff] [blame] | 740 | file = __fget(fd, mask); |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 741 | if (!file) |
| 742 | return 0; |
| 743 | return FDPUT_FPUT | (unsigned long)file; |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 744 | } |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 745 | } |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 746 | unsigned long __fdget(unsigned int fd) |
Oleg Nesterov | ad46183 | 2014-01-13 16:48:40 +0100 | [diff] [blame] | 747 | { |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 748 | return __fget_light(fd, FMODE_PATH); |
Oleg Nesterov | ad46183 | 2014-01-13 16:48:40 +0100 | [diff] [blame] | 749 | } |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 750 | EXPORT_SYMBOL(__fdget); |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 751 | |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 752 | unsigned long __fdget_raw(unsigned int fd) |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 753 | { |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 754 | return __fget_light(fd, 0); |
Al Viro | 0ee8cdf | 2012-08-15 21:12:10 -0400 | [diff] [blame] | 755 | } |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 756 | |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 757 | unsigned long __fdget_pos(unsigned int fd) |
| 758 | { |
Eric Biggers | 99aea68 | 2014-03-16 15:47:48 -0500 | [diff] [blame] | 759 | unsigned long v = __fdget(fd); |
| 760 | struct file *file = (struct file *)(v & ~3); |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 761 | |
Eric Biggers | 99aea68 | 2014-03-16 15:47:48 -0500 | [diff] [blame] | 762 | if (file && (file->f_mode & FMODE_ATOMIC_POS)) { |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 763 | if (file_count(file) > 1) { |
| 764 | v |= FDPUT_POS_UNLOCK; |
| 765 | mutex_lock(&file->f_pos_lock); |
| 766 | } |
| 767 | } |
Eric Biggers | 99aea68 | 2014-03-16 15:47:48 -0500 | [diff] [blame] | 768 | return v; |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 769 | } |
| 770 | |
Al Viro | 63b6df1 | 2016-04-20 17:08:21 -0400 | [diff] [blame] | 771 | void __f_unlock_pos(struct file *f) |
| 772 | { |
| 773 | mutex_unlock(&f->f_pos_lock); |
| 774 | } |
| 775 | |
Al Viro | bd2a31d | 2014-03-04 14:54:22 -0500 | [diff] [blame] | 776 | /* |
| 777 | * We only lock f_pos if we have threads or if the file might be |
| 778 | * shared with another process. In both cases we'll have an elevated |
| 779 | * file count (done either by fdget() or by fork()). |
| 780 | */ |
| 781 | |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 782 | void set_close_on_exec(unsigned int fd, int flag) |
| 783 | { |
| 784 | struct files_struct *files = current->files; |
| 785 | struct fdtable *fdt; |
| 786 | spin_lock(&files->file_lock); |
| 787 | fdt = files_fdtable(files); |
| 788 | if (flag) |
| 789 | __set_close_on_exec(fd, fdt); |
| 790 | else |
| 791 | __clear_close_on_exec(fd, fdt); |
| 792 | spin_unlock(&files->file_lock); |
| 793 | } |
| 794 | |
| 795 | bool get_close_on_exec(unsigned int fd) |
| 796 | { |
| 797 | struct files_struct *files = current->files; |
| 798 | struct fdtable *fdt; |
| 799 | bool res; |
| 800 | rcu_read_lock(); |
| 801 | fdt = files_fdtable(files); |
| 802 | res = close_on_exec(fd, fdt); |
| 803 | rcu_read_unlock(); |
| 804 | return res; |
| 805 | } |
| 806 | |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 807 | static int do_dup2(struct files_struct *files, |
| 808 | struct file *file, unsigned fd, unsigned flags) |
Al Viro | e983094 | 2014-08-31 14:12:09 -0400 | [diff] [blame] | 809 | __releases(&files->file_lock) |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 810 | { |
| 811 | struct file *tofree; |
| 812 | struct fdtable *fdt; |
| 813 | |
| 814 | /* |
| 815 | * We need to detect attempts to do dup2() over allocated but still |
| 816 | * not finished descriptor. NB: OpenBSD avoids that at the price of |
| 817 | * extra work in their equivalent of fget() - they insert struct |
| 818 | * file immediately after grabbing descriptor, mark it larval if |
| 819 | * more work (e.g. actual opening) is needed and make sure that |
| 820 | * fget() treats larval files as absent. Potentially interesting, |
| 821 | * but while extra work in fget() is trivial, locking implications |
| 822 | * and amount of surgery on open()-related paths in VFS are not. |
| 823 | * FreeBSD fails with -EBADF in the same situation, NetBSD "solution" |
| 824 | * deadlocks in rather amusing ways, AFAICS. All of that is out of |
| 825 | * scope of POSIX or SUS, since neither considers shared descriptor |
| 826 | * tables and this condition does not arise without those. |
| 827 | */ |
| 828 | fdt = files_fdtable(files); |
| 829 | tofree = fdt->fd[fd]; |
| 830 | if (!tofree && fd_is_open(fd, fdt)) |
| 831 | goto Ebusy; |
| 832 | get_file(file); |
| 833 | rcu_assign_pointer(fdt->fd[fd], file); |
| 834 | __set_open_fd(fd, fdt); |
| 835 | if (flags & O_CLOEXEC) |
| 836 | __set_close_on_exec(fd, fdt); |
| 837 | else |
| 838 | __clear_close_on_exec(fd, fdt); |
| 839 | spin_unlock(&files->file_lock); |
| 840 | |
| 841 | if (tofree) |
| 842 | filp_close(tofree, files); |
| 843 | |
| 844 | return fd; |
| 845 | |
| 846 | Ebusy: |
| 847 | spin_unlock(&files->file_lock); |
| 848 | return -EBUSY; |
| 849 | } |
| 850 | |
| 851 | int replace_fd(unsigned fd, struct file *file, unsigned flags) |
| 852 | { |
| 853 | int err; |
| 854 | struct files_struct *files = current->files; |
| 855 | |
| 856 | if (!file) |
| 857 | return __close_fd(files, fd); |
| 858 | |
| 859 | if (fd >= rlimit(RLIMIT_NOFILE)) |
Al Viro | 08f05c4 | 2012-10-31 03:37:48 +0000 | [diff] [blame] | 860 | return -EBADF; |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 861 | |
| 862 | spin_lock(&files->file_lock); |
| 863 | err = expand_files(files, fd); |
| 864 | if (unlikely(err < 0)) |
| 865 | goto out_unlock; |
| 866 | return do_dup2(files, file, fd, flags); |
| 867 | |
| 868 | out_unlock: |
| 869 | spin_unlock(&files->file_lock); |
| 870 | return err; |
| 871 | } |
| 872 | |
Dominik Brodowski | c724832 | 2018-03-11 11:34:40 +0100 | [diff] [blame^] | 873 | static int ksys_dup3(unsigned int oldfd, unsigned int newfd, int flags) |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 874 | { |
| 875 | int err = -EBADF; |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 876 | struct file *file; |
| 877 | struct files_struct *files = current->files; |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 878 | |
| 879 | if ((flags & ~O_CLOEXEC) != 0) |
| 880 | return -EINVAL; |
| 881 | |
Richard W.M. Jones | aed9764 | 2012-10-09 15:27:43 +0100 | [diff] [blame] | 882 | if (unlikely(oldfd == newfd)) |
| 883 | return -EINVAL; |
| 884 | |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 885 | if (newfd >= rlimit(RLIMIT_NOFILE)) |
Al Viro | 08f05c4 | 2012-10-31 03:37:48 +0000 | [diff] [blame] | 886 | return -EBADF; |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 887 | |
| 888 | spin_lock(&files->file_lock); |
| 889 | err = expand_files(files, newfd); |
| 890 | file = fcheck(oldfd); |
| 891 | if (unlikely(!file)) |
| 892 | goto Ebadf; |
| 893 | if (unlikely(err < 0)) { |
| 894 | if (err == -EMFILE) |
| 895 | goto Ebadf; |
| 896 | goto out_unlock; |
| 897 | } |
Al Viro | 8280d16 | 2012-08-21 12:11:46 -0400 | [diff] [blame] | 898 | return do_dup2(files, file, newfd, flags); |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 899 | |
| 900 | Ebadf: |
| 901 | err = -EBADF; |
| 902 | out_unlock: |
| 903 | spin_unlock(&files->file_lock); |
| 904 | return err; |
| 905 | } |
| 906 | |
Dominik Brodowski | c724832 | 2018-03-11 11:34:40 +0100 | [diff] [blame^] | 907 | SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags) |
| 908 | { |
| 909 | return ksys_dup3(oldfd, newfd, flags); |
| 910 | } |
| 911 | |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 912 | SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd) |
| 913 | { |
| 914 | if (unlikely(newfd == oldfd)) { /* corner case */ |
| 915 | struct files_struct *files = current->files; |
| 916 | int retval = oldfd; |
| 917 | |
| 918 | rcu_read_lock(); |
| 919 | if (!fcheck_files(files, oldfd)) |
| 920 | retval = -EBADF; |
| 921 | rcu_read_unlock(); |
| 922 | return retval; |
| 923 | } |
Dominik Brodowski | c724832 | 2018-03-11 11:34:40 +0100 | [diff] [blame^] | 924 | return ksys_dup3(oldfd, newfd, 0); |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 925 | } |
| 926 | |
Dominik Brodowski | c724832 | 2018-03-11 11:34:40 +0100 | [diff] [blame^] | 927 | int ksys_dup(unsigned int fildes) |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 928 | { |
| 929 | int ret = -EBADF; |
| 930 | struct file *file = fget_raw(fildes); |
| 931 | |
| 932 | if (file) { |
Yann Droneaud | 8d10a03 | 2014-12-10 15:45:44 -0800 | [diff] [blame] | 933 | ret = get_unused_fd_flags(0); |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 934 | if (ret >= 0) |
| 935 | fd_install(ret, file); |
| 936 | else |
| 937 | fput(file); |
| 938 | } |
| 939 | return ret; |
| 940 | } |
| 941 | |
Dominik Brodowski | c724832 | 2018-03-11 11:34:40 +0100 | [diff] [blame^] | 942 | SYSCALL_DEFINE1(dup, unsigned int, fildes) |
| 943 | { |
| 944 | return ksys_dup(fildes); |
| 945 | } |
| 946 | |
Al Viro | fe17f22 | 2012-08-21 11:48:11 -0400 | [diff] [blame] | 947 | int f_dupfd(unsigned int from, struct file *file, unsigned flags) |
| 948 | { |
| 949 | int err; |
| 950 | if (from >= rlimit(RLIMIT_NOFILE)) |
| 951 | return -EINVAL; |
| 952 | err = alloc_fd(from, flags); |
| 953 | if (err >= 0) { |
| 954 | get_file(file); |
| 955 | fd_install(err, file); |
| 956 | } |
| 957 | return err; |
| 958 | } |
Al Viro | c3c073f | 2012-08-21 22:32:06 -0400 | [diff] [blame] | 959 | |
| 960 | int iterate_fd(struct files_struct *files, unsigned n, |
| 961 | int (*f)(const void *, struct file *, unsigned), |
| 962 | const void *p) |
| 963 | { |
| 964 | struct fdtable *fdt; |
Al Viro | c3c073f | 2012-08-21 22:32:06 -0400 | [diff] [blame] | 965 | int res = 0; |
| 966 | if (!files) |
| 967 | return 0; |
| 968 | spin_lock(&files->file_lock); |
Al Viro | a77cfcb | 2012-11-29 22:57:33 -0500 | [diff] [blame] | 969 | for (fdt = files_fdtable(files); n < fdt->max_fds; n++) { |
| 970 | struct file *file; |
| 971 | file = rcu_dereference_check_fdtable(files, fdt->fd[n]); |
| 972 | if (!file) |
| 973 | continue; |
| 974 | res = f(p, file, n); |
| 975 | if (res) |
| 976 | break; |
Al Viro | c3c073f | 2012-08-21 22:32:06 -0400 | [diff] [blame] | 977 | } |
| 978 | spin_unlock(&files->file_lock); |
| 979 | return res; |
| 980 | } |
| 981 | EXPORT_SYMBOL(iterate_fd); |