blob: 1fbc5c0555a9caefb153f9b07cbc716583ef658e [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/file.c
3 *
4 * Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes
5 *
6 * Manage the dynamic fd arrays in the process files_struct.
7 */
8
Al Virofe17f222012-08-21 11:48:11 -04009#include <linux/syscalls.h>
Paul Gortmaker630d9c42011-11-16 23:57:37 -050010#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070011#include <linux/fs.h>
12#include <linux/mm.h>
Andrew Morton6d4831c2011-04-27 15:26:41 -070013#include <linux/mmzone.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/time.h>
Alexey Dobriyand43c36d2009-10-07 17:09:06 +040015#include <linux/sched.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/slab.h>
17#include <linux/vmalloc.h>
18#include <linux/file.h>
Al Viro9f3acc32008-04-24 07:44:08 -040019#include <linux/fdtable.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/bitops.h>
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070021#include <linux/interrupt.h>
22#include <linux/spinlock.h>
23#include <linux/rcupdate.h>
24#include <linux/workqueue.h>
25
Eric Dumazet9cfe0152008-02-06 01:37:16 -080026int sysctl_nr_open __read_mostly = 1024*1024;
Al Viroeceea0b2008-05-10 10:08:32 -040027int sysctl_nr_open_min = BITS_PER_LONG;
Rasmus Villemoes752343b2015-10-29 12:01:41 +010028/* our min() is unusable in constant expressions ;-/ */
29#define __const_min(x, y) ((x) < (y) ? (x) : (y))
30int sysctl_nr_open_max = __const_min(INT_MAX, ~(size_t)0/sizeof(void *)) &
Al Viro7f4b36f2014-03-14 12:45:29 -040031 -BITS_PER_LONG;
Eric Dumazet9cfe0152008-02-06 01:37:16 -080032
David Howells1fd36ad2012-02-16 17:49:54 +000033static void *alloc_fdmem(size_t size)
Linus Torvalds1da177e2005-04-16 15:20:36 -070034{
Andrew Morton6d4831c2011-04-27 15:26:41 -070035 /*
36 * Very large allocations can stress page reclaim, so fall back to
37 * vmalloc() if the allocation size will be considered "large" by the VM.
38 */
39 if (size <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER)) {
Vladimir Davydov5d097052016-01-14 15:18:21 -080040 void *data = kmalloc(size, GFP_KERNEL_ACCOUNT |
41 __GFP_NOWARN | __GFP_NORETRY);
Andrew Morton6d4831c2011-04-27 15:26:41 -070042 if (data != NULL)
43 return data;
44 }
Vladimir Davydov5d097052016-01-14 15:18:21 -080045 return __vmalloc(size, GFP_KERNEL_ACCOUNT | __GFP_HIGHMEM, PAGE_KERNEL);
Linus Torvalds1da177e2005-04-16 15:20:36 -070046}
47
Changli Gaoa892e2d2010-08-10 18:01:35 -070048static void __free_fdtable(struct fdtable *fdt)
Vadim Lobanov5466b452006-12-10 02:21:22 -080049{
Al Virof6c0a192014-04-23 10:18:46 -040050 kvfree(fdt->fd);
51 kvfree(fdt->open_fds);
Changli Gaoa892e2d2010-08-10 18:01:35 -070052 kfree(fdt);
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070053}
54
Al Viro7cf4dc32012-08-15 19:56:12 -040055static void free_fdtable_rcu(struct rcu_head *rcu)
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070056{
Al Viroac3e3c52013-04-28 21:42:33 -040057 __free_fdtable(container_of(rcu, struct fdtable, rcu));
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070058}
59
Linus Torvaldsf3f86e32015-10-30 16:53:57 -070060#define BITBIT_NR(nr) BITS_TO_LONGS(BITS_TO_LONGS(nr))
61#define BITBIT_SIZE(nr) (BITBIT_NR(nr) * sizeof(long))
62
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070063/*
Eric Biggersea5c58e2015-11-06 00:32:04 -060064 * Copy 'count' fd bits from the old table to the new table and clear the extra
65 * space if any. This does not copy the file pointers. Called with the files
66 * spinlock held for write.
67 */
68static void copy_fd_bitmaps(struct fdtable *nfdt, struct fdtable *ofdt,
69 unsigned int count)
70{
71 unsigned int cpy, set;
72
73 cpy = count / BITS_PER_BYTE;
74 set = (nfdt->max_fds - count) / BITS_PER_BYTE;
75 memcpy(nfdt->open_fds, ofdt->open_fds, cpy);
76 memset((char *)nfdt->open_fds + cpy, 0, set);
77 memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy);
78 memset((char *)nfdt->close_on_exec + cpy, 0, set);
79
80 cpy = BITBIT_SIZE(count);
81 set = BITBIT_SIZE(nfdt->max_fds) - cpy;
82 memcpy(nfdt->full_fds_bits, ofdt->full_fds_bits, cpy);
83 memset((char *)nfdt->full_fds_bits + cpy, 0, set);
84}
85
86/*
87 * Copy all file descriptors from the old table to the new, expanded table and
88 * clear the extra space. Called with the files spinlock held for write.
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070089 */
Vadim Lobanov5466b452006-12-10 02:21:22 -080090static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt)
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070091{
Vadim Lobanov5466b452006-12-10 02:21:22 -080092 unsigned int cpy, set;
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -070093
Vadim Lobanov5466b452006-12-10 02:21:22 -080094 BUG_ON(nfdt->max_fds < ofdt->max_fds);
Vadim Lobanov5466b452006-12-10 02:21:22 -080095
96 cpy = ofdt->max_fds * sizeof(struct file *);
97 set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *);
98 memcpy(nfdt->fd, ofdt->fd, cpy);
Eric Biggersea5c58e2015-11-06 00:32:04 -060099 memset((char *)nfdt->fd + cpy, 0, set);
Vadim Lobanov5466b452006-12-10 02:21:22 -0800100
Eric Biggersea5c58e2015-11-06 00:32:04 -0600101 copy_fd_bitmaps(nfdt, ofdt, ofdt->max_fds);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102}
103
Vadim Lobanov5466b452006-12-10 02:21:22 -0800104static struct fdtable * alloc_fdtable(unsigned int nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105{
Vadim Lobanov5466b452006-12-10 02:21:22 -0800106 struct fdtable *fdt;
David Howells1fd36ad2012-02-16 17:49:54 +0000107 void *data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700109 /*
Vadim Lobanov5466b452006-12-10 02:21:22 -0800110 * Figure out how many fds we actually want to support in this fdtable.
111 * Allocation steps are keyed to the size of the fdarray, since it
112 * grows far faster than any of the other dynamic data. We try to fit
113 * the fdarray into comfortable page-tuned chunks: starting at 1024B
114 * and growing in powers of two from there on.
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700115 */
Vadim Lobanov5466b452006-12-10 02:21:22 -0800116 nr /= (1024 / sizeof(struct file *));
117 nr = roundup_pow_of_two(nr + 1);
118 nr *= (1024 / sizeof(struct file *));
Al Viro5c598b32008-04-27 20:04:15 -0400119 /*
120 * Note that this can drive nr *below* what we had passed if sysctl_nr_open
121 * had been set lower between the check in expand_files() and here. Deal
122 * with that in caller, it's cheaper that way.
123 *
124 * We make sure that nr remains a multiple of BITS_PER_LONG - otherwise
125 * bitmaps handling below becomes unpleasant, to put it mildly...
126 */
127 if (unlikely(nr > sysctl_nr_open))
128 nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1;
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800129
Vladimir Davydov5d097052016-01-14 15:18:21 -0800130 fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL_ACCOUNT);
Vadim Lobanov5466b452006-12-10 02:21:22 -0800131 if (!fdt)
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800132 goto out;
Vadim Lobanov5466b452006-12-10 02:21:22 -0800133 fdt->max_fds = nr;
134 data = alloc_fdmem(nr * sizeof(struct file *));
135 if (!data)
136 goto out_fdt;
David Howells1fd36ad2012-02-16 17:49:54 +0000137 fdt->fd = data;
138
139 data = alloc_fdmem(max_t(size_t,
Linus Torvaldsf3f86e32015-10-30 16:53:57 -0700140 2 * nr / BITS_PER_BYTE + BITBIT_SIZE(nr), L1_CACHE_BYTES));
Vadim Lobanov5466b452006-12-10 02:21:22 -0800141 if (!data)
142 goto out_arr;
David Howells1fd36ad2012-02-16 17:49:54 +0000143 fdt->open_fds = data;
Vadim Lobanov5466b452006-12-10 02:21:22 -0800144 data += nr / BITS_PER_BYTE;
David Howells1fd36ad2012-02-16 17:49:54 +0000145 fdt->close_on_exec = data;
Linus Torvaldsf3f86e32015-10-30 16:53:57 -0700146 data += nr / BITS_PER_BYTE;
147 fdt->full_fds_bits = data;
Vadim Lobanov5466b452006-12-10 02:21:22 -0800148
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700149 return fdt;
Vadim Lobanov5466b452006-12-10 02:21:22 -0800150
151out_arr:
Al Virof6c0a192014-04-23 10:18:46 -0400152 kvfree(fdt->fd);
Vadim Lobanov5466b452006-12-10 02:21:22 -0800153out_fdt:
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700154 kfree(fdt);
Vadim Lobanov5466b452006-12-10 02:21:22 -0800155out:
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700156 return NULL;
157}
158
159/*
Vadim Lobanov74d392a2006-09-29 02:01:43 -0700160 * Expand the file descriptor table.
161 * This function will allocate a new fdtable and both fd array and fdset, of
162 * the given size.
163 * Return <0 error code on error; 1 on successful completion.
164 * The files->file_lock should be held on entry, and will be held on exit.
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700165 */
166static int expand_fdtable(struct files_struct *files, int nr)
167 __releases(files->file_lock)
168 __acquires(files->file_lock)
169{
Vadim Lobanov74d392a2006-09-29 02:01:43 -0700170 struct fdtable *new_fdt, *cur_fdt;
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700171
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 spin_unlock(&files->file_lock);
Vadim Lobanov74d392a2006-09-29 02:01:43 -0700173 new_fdt = alloc_fdtable(nr);
Eric Dumazet8a812522015-06-30 15:54:08 +0200174
175 /* make sure all __fd_install() have seen resize_in_progress
176 * or have finished their rcu_read_lock_sched() section.
177 */
178 if (atomic_read(&files->count) > 1)
179 synchronize_sched();
180
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 spin_lock(&files->file_lock);
Vadim Lobanov74d392a2006-09-29 02:01:43 -0700182 if (!new_fdt)
183 return -ENOMEM;
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700184 /*
Al Viro5c598b32008-04-27 20:04:15 -0400185 * extremely unlikely race - sysctl_nr_open decreased between the check in
186 * caller and alloc_fdtable(). Cheaper to catch it here...
187 */
188 if (unlikely(new_fdt->max_fds <= nr)) {
Changli Gaoa892e2d2010-08-10 18:01:35 -0700189 __free_fdtable(new_fdt);
Al Viro5c598b32008-04-27 20:04:15 -0400190 return -EMFILE;
191 }
Vadim Lobanov74d392a2006-09-29 02:01:43 -0700192 cur_fdt = files_fdtable(files);
Eric Dumazet8a812522015-06-30 15:54:08 +0200193 BUG_ON(nr < cur_fdt->max_fds);
194 copy_fdtable(new_fdt, cur_fdt);
195 rcu_assign_pointer(files->fdt, new_fdt);
196 if (cur_fdt != &files->fdtab)
197 call_rcu(&cur_fdt->rcu, free_fdtable_rcu);
198 /* coupled with smp_rmb() in __fd_install() */
199 smp_wmb();
Vadim Lobanov74d392a2006-09-29 02:01:43 -0700200 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201}
202
203/*
204 * Expand files.
Vadim Lobanov74d392a2006-09-29 02:01:43 -0700205 * This function will expand the file structures, if the requested size exceeds
206 * the current capacity and there is room for expansion.
207 * Return <0 error code on error; 0 when nothing done; 1 when files were
208 * expanded and execution may have blocked.
209 * The files->file_lock should be held on entry, and will be held on exit.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 */
Al Viroad47bd72012-08-21 20:11:34 -0400211static int expand_files(struct files_struct *files, int nr)
Eric Dumazet8a812522015-06-30 15:54:08 +0200212 __releases(files->file_lock)
213 __acquires(files->file_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214{
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700215 struct fdtable *fdt;
Eric Dumazet8a812522015-06-30 15:54:08 +0200216 int expanded = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217
Eric Dumazet8a812522015-06-30 15:54:08 +0200218repeat:
Dipankar Sarmabadf1662005-09-09 13:04:10 -0700219 fdt = files_fdtable(files);
Al Viro4e1e0182008-07-26 16:01:20 -0400220
Vadim Lobanov74d392a2006-09-29 02:01:43 -0700221 /* Do we need to expand? */
Vadim Lobanovbbea9f62006-12-10 02:21:12 -0800222 if (nr < fdt->max_fds)
Eric Dumazet8a812522015-06-30 15:54:08 +0200223 return expanded;
Al Viro4e1e0182008-07-26 16:01:20 -0400224
Vadim Lobanov74d392a2006-09-29 02:01:43 -0700225 /* Can we expand? */
Eric Dumazet9cfe0152008-02-06 01:37:16 -0800226 if (nr >= sysctl_nr_open)
Vadim Lobanov74d392a2006-09-29 02:01:43 -0700227 return -EMFILE;
228
Eric Dumazet8a812522015-06-30 15:54:08 +0200229 if (unlikely(files->resize_in_progress)) {
230 spin_unlock(&files->file_lock);
231 expanded = 1;
232 wait_event(files->resize_wait, !files->resize_in_progress);
233 spin_lock(&files->file_lock);
234 goto repeat;
235 }
236
Vadim Lobanov74d392a2006-09-29 02:01:43 -0700237 /* All good, so we try */
Eric Dumazet8a812522015-06-30 15:54:08 +0200238 files->resize_in_progress = true;
239 expanded = expand_fdtable(files, nr);
240 files->resize_in_progress = false;
241
242 wake_up_all(&files->resize_wait);
243 return expanded;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244}
Dipankar Sarmaab2af1f2005-09-09 13:04:13 -0700245
Al Virob8318b02012-08-21 20:09:42 -0400246static inline void __set_close_on_exec(int fd, struct fdtable *fdt)
247{
248 __set_bit(fd, fdt->close_on_exec);
249}
250
251static inline void __clear_close_on_exec(int fd, struct fdtable *fdt)
252{
Linus Torvaldsfc908882015-10-31 16:06:40 -0700253 if (test_bit(fd, fdt->close_on_exec))
254 __clear_bit(fd, fdt->close_on_exec);
Al Virob8318b02012-08-21 20:09:42 -0400255}
256
Linus Torvaldsf3f86e32015-10-30 16:53:57 -0700257static inline void __set_open_fd(unsigned int fd, struct fdtable *fdt)
Al Virob8318b02012-08-21 20:09:42 -0400258{
259 __set_bit(fd, fdt->open_fds);
Linus Torvaldsf3f86e32015-10-30 16:53:57 -0700260 fd /= BITS_PER_LONG;
261 if (!~fdt->open_fds[fd])
262 __set_bit(fd, fdt->full_fds_bits);
Al Virob8318b02012-08-21 20:09:42 -0400263}
264
Linus Torvaldsf3f86e32015-10-30 16:53:57 -0700265static inline void __clear_open_fd(unsigned int fd, struct fdtable *fdt)
Al Virob8318b02012-08-21 20:09:42 -0400266{
267 __clear_bit(fd, fdt->open_fds);
Linus Torvaldsf3f86e32015-10-30 16:53:57 -0700268 __clear_bit(fd / BITS_PER_LONG, fdt->full_fds_bits);
Al Virob8318b02012-08-21 20:09:42 -0400269}
270
Al Viro02afc6262008-05-08 19:42:56 -0400271static int count_open_files(struct fdtable *fdt)
272{
273 int size = fdt->max_fds;
274 int i;
275
276 /* Find the last open fd */
David Howells1fd36ad2012-02-16 17:49:54 +0000277 for (i = size / BITS_PER_LONG; i > 0; ) {
278 if (fdt->open_fds[--i])
Al Viro02afc6262008-05-08 19:42:56 -0400279 break;
280 }
David Howells1fd36ad2012-02-16 17:49:54 +0000281 i = (i + 1) * BITS_PER_LONG;
Al Viro02afc6262008-05-08 19:42:56 -0400282 return i;
283}
284
Al Viro02afc6262008-05-08 19:42:56 -0400285/*
286 * Allocate a new files structure and copy contents from the
287 * passed in files structure.
288 * errorp will be valid only when the returned files_struct is NULL.
289 */
290struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
291{
292 struct files_struct *newf;
293 struct file **old_fds, **new_fds;
Eric Biggersea5c58e2015-11-06 00:32:04 -0600294 int open_files, i;
Al Viro02afc6262008-05-08 19:42:56 -0400295 struct fdtable *old_fdt, *new_fdt;
296
297 *errorp = -ENOMEM;
Al Viroafbec7f2008-05-08 21:11:17 -0400298 newf = kmem_cache_alloc(files_cachep, GFP_KERNEL);
Al Viro02afc6262008-05-08 19:42:56 -0400299 if (!newf)
300 goto out;
301
Al Viroafbec7f2008-05-08 21:11:17 -0400302 atomic_set(&newf->count, 1);
303
304 spin_lock_init(&newf->file_lock);
Eric Dumazet8a812522015-06-30 15:54:08 +0200305 newf->resize_in_progress = false;
306 init_waitqueue_head(&newf->resize_wait);
Al Viroafbec7f2008-05-08 21:11:17 -0400307 newf->next_fd = 0;
308 new_fdt = &newf->fdtab;
309 new_fdt->max_fds = NR_OPEN_DEFAULT;
David Howells1fd36ad2012-02-16 17:49:54 +0000310 new_fdt->close_on_exec = newf->close_on_exec_init;
311 new_fdt->open_fds = newf->open_fds_init;
Linus Torvaldsf3f86e32015-10-30 16:53:57 -0700312 new_fdt->full_fds_bits = newf->full_fds_bits_init;
Al Viroafbec7f2008-05-08 21:11:17 -0400313 new_fdt->fd = &newf->fd_array[0];
Al Viroafbec7f2008-05-08 21:11:17 -0400314
Al Viro02afc6262008-05-08 19:42:56 -0400315 spin_lock(&oldf->file_lock);
316 old_fdt = files_fdtable(oldf);
Al Viro02afc6262008-05-08 19:42:56 -0400317 open_files = count_open_files(old_fdt);
318
319 /*
320 * Check whether we need to allocate a larger fd array and fd set.
Al Viro02afc6262008-05-08 19:42:56 -0400321 */
Al Viroadbecb12008-05-08 21:19:42 -0400322 while (unlikely(open_files > new_fdt->max_fds)) {
Al Viro02afc6262008-05-08 19:42:56 -0400323 spin_unlock(&oldf->file_lock);
Al Viro9dec3c42008-05-08 21:02:45 -0400324
Changli Gaoa892e2d2010-08-10 18:01:35 -0700325 if (new_fdt != &newf->fdtab)
326 __free_fdtable(new_fdt);
Al Viroadbecb12008-05-08 21:19:42 -0400327
Al Viro9dec3c42008-05-08 21:02:45 -0400328 new_fdt = alloc_fdtable(open_files - 1);
329 if (!new_fdt) {
330 *errorp = -ENOMEM;
Al Viro02afc6262008-05-08 19:42:56 -0400331 goto out_release;
Al Viro9dec3c42008-05-08 21:02:45 -0400332 }
333
334 /* beyond sysctl_nr_open; nothing to do */
335 if (unlikely(new_fdt->max_fds < open_files)) {
Changli Gaoa892e2d2010-08-10 18:01:35 -0700336 __free_fdtable(new_fdt);
Al Viro9dec3c42008-05-08 21:02:45 -0400337 *errorp = -EMFILE;
338 goto out_release;
339 }
Al Viro9dec3c42008-05-08 21:02:45 -0400340
Al Viro02afc6262008-05-08 19:42:56 -0400341 /*
342 * Reacquire the oldf lock and a pointer to its fd table
343 * who knows it may have a new bigger fd table. We need
344 * the latest pointer.
345 */
346 spin_lock(&oldf->file_lock);
347 old_fdt = files_fdtable(oldf);
Al Viroadbecb12008-05-08 21:19:42 -0400348 open_files = count_open_files(old_fdt);
Al Viro02afc6262008-05-08 19:42:56 -0400349 }
350
Eric Biggersea5c58e2015-11-06 00:32:04 -0600351 copy_fd_bitmaps(new_fdt, old_fdt, open_files);
352
Al Viro02afc6262008-05-08 19:42:56 -0400353 old_fds = old_fdt->fd;
354 new_fds = new_fdt->fd;
355
Al Viro02afc6262008-05-08 19:42:56 -0400356 for (i = open_files; i != 0; i--) {
357 struct file *f = *old_fds++;
358 if (f) {
359 get_file(f);
360 } else {
361 /*
362 * The fd may be claimed in the fd bitmap but not yet
363 * instantiated in the files array if a sibling thread
364 * is partway through open(). So make sure that this
365 * fd is available to the new process.
366 */
David Howells1dce27c2012-02-16 17:49:42 +0000367 __clear_open_fd(open_files - i, new_fdt);
Al Viro02afc6262008-05-08 19:42:56 -0400368 }
369 rcu_assign_pointer(*new_fds++, f);
370 }
371 spin_unlock(&oldf->file_lock);
372
Eric Biggersea5c58e2015-11-06 00:32:04 -0600373 /* clear the remainder */
374 memset(new_fds, 0, (new_fdt->max_fds - open_files) * sizeof(struct file *));
Al Viro02afc6262008-05-08 19:42:56 -0400375
Al Viroafbec7f2008-05-08 21:11:17 -0400376 rcu_assign_pointer(newf->fdt, new_fdt);
377
Al Viro02afc6262008-05-08 19:42:56 -0400378 return newf;
379
380out_release:
381 kmem_cache_free(files_cachep, newf);
382out:
383 return NULL;
384}
385
Oleg Nesterovce08b622014-01-11 19:19:53 +0100386static struct fdtable *close_files(struct files_struct * files)
Al Viro7cf4dc32012-08-15 19:56:12 -0400387{
Al Viro7cf4dc32012-08-15 19:56:12 -0400388 /*
389 * It is safe to dereference the fd table without RCU or
390 * ->file_lock because this is the last reference to the
Oleg Nesterovce08b622014-01-11 19:19:53 +0100391 * files structure.
Al Viro7cf4dc32012-08-15 19:56:12 -0400392 */
Oleg Nesterovce08b622014-01-11 19:19:53 +0100393 struct fdtable *fdt = rcu_dereference_raw(files->fdt);
394 int i, j = 0;
395
Al Viro7cf4dc32012-08-15 19:56:12 -0400396 for (;;) {
397 unsigned long set;
398 i = j * BITS_PER_LONG;
399 if (i >= fdt->max_fds)
400 break;
401 set = fdt->open_fds[j++];
402 while (set) {
403 if (set & 1) {
404 struct file * file = xchg(&fdt->fd[i], NULL);
405 if (file) {
406 filp_close(file, files);
Paul E. McKenneybde6c3a2014-07-01 11:26:57 -0700407 cond_resched_rcu_qs();
Al Viro7cf4dc32012-08-15 19:56:12 -0400408 }
409 }
410 i++;
411 set >>= 1;
412 }
413 }
Oleg Nesterovce08b622014-01-11 19:19:53 +0100414
415 return fdt;
Al Viro7cf4dc32012-08-15 19:56:12 -0400416}
417
418struct files_struct *get_files_struct(struct task_struct *task)
419{
420 struct files_struct *files;
421
422 task_lock(task);
423 files = task->files;
424 if (files)
425 atomic_inc(&files->count);
426 task_unlock(task);
427
428 return files;
429}
430
431void put_files_struct(struct files_struct *files)
432{
Al Viro7cf4dc32012-08-15 19:56:12 -0400433 if (atomic_dec_and_test(&files->count)) {
Oleg Nesterovce08b622014-01-11 19:19:53 +0100434 struct fdtable *fdt = close_files(files);
435
Al Virob9e02af2012-08-15 20:00:58 -0400436 /* free the arrays if they are not embedded */
437 if (fdt != &files->fdtab)
438 __free_fdtable(fdt);
439 kmem_cache_free(files_cachep, files);
Al Viro7cf4dc32012-08-15 19:56:12 -0400440 }
441}
442
443void reset_files_struct(struct files_struct *files)
444{
445 struct task_struct *tsk = current;
446 struct files_struct *old;
447
448 old = tsk->files;
449 task_lock(tsk);
450 tsk->files = files;
451 task_unlock(tsk);
452 put_files_struct(old);
453}
454
455void exit_files(struct task_struct *tsk)
456{
457 struct files_struct * files = tsk->files;
458
459 if (files) {
460 task_lock(tsk);
461 tsk->files = NULL;
462 task_unlock(tsk);
463 put_files_struct(files);
464 }
465}
466
Al Virof52111b2008-05-08 18:19:16 -0400467struct files_struct init_files = {
468 .count = ATOMIC_INIT(1),
469 .fdt = &init_files.fdtab,
470 .fdtab = {
471 .max_fds = NR_OPEN_DEFAULT,
472 .fd = &init_files.fd_array[0],
David Howells1fd36ad2012-02-16 17:49:54 +0000473 .close_on_exec = init_files.close_on_exec_init,
474 .open_fds = init_files.open_fds_init,
Linus Torvaldsf3f86e32015-10-30 16:53:57 -0700475 .full_fds_bits = init_files.full_fds_bits_init,
Al Virof52111b2008-05-08 18:19:16 -0400476 },
Thomas Gleixnereece09e2011-07-17 21:25:03 +0200477 .file_lock = __SPIN_LOCK_UNLOCKED(init_files.file_lock),
Al Virof52111b2008-05-08 18:19:16 -0400478};
Al Viro1027abe2008-07-30 04:13:04 -0400479
Linus Torvaldsf3f86e32015-10-30 16:53:57 -0700480static unsigned long find_next_fd(struct fdtable *fdt, unsigned long start)
481{
482 unsigned long maxfd = fdt->max_fds;
483 unsigned long maxbit = maxfd / BITS_PER_LONG;
484 unsigned long bitbit = start / BITS_PER_LONG;
485
486 bitbit = find_next_zero_bit(fdt->full_fds_bits, maxbit, bitbit) * BITS_PER_LONG;
487 if (bitbit > maxfd)
488 return maxfd;
489 if (bitbit > start)
490 start = bitbit;
491 return find_next_zero_bit(fdt->open_fds, maxfd, start);
492}
493
Al Viro1027abe2008-07-30 04:13:04 -0400494/*
495 * allocate a file descriptor, mark it busy.
496 */
Al Virodcfadfa2012-08-12 17:27:30 -0400497int __alloc_fd(struct files_struct *files,
498 unsigned start, unsigned end, unsigned flags)
Al Viro1027abe2008-07-30 04:13:04 -0400499{
Al Viro1027abe2008-07-30 04:13:04 -0400500 unsigned int fd;
501 int error;
502 struct fdtable *fdt;
503
504 spin_lock(&files->file_lock);
505repeat:
506 fdt = files_fdtable(files);
507 fd = start;
508 if (fd < files->next_fd)
509 fd = files->next_fd;
510
511 if (fd < fdt->max_fds)
Linus Torvaldsf3f86e32015-10-30 16:53:57 -0700512 fd = find_next_fd(fdt, fd);
Al Viro1027abe2008-07-30 04:13:04 -0400513
Al Virof33ff992012-08-12 16:17:59 -0400514 /*
515 * N.B. For clone tasks sharing a files structure, this test
516 * will limit the total number of files that can be opened.
517 */
518 error = -EMFILE;
519 if (fd >= end)
520 goto out;
521
Al Viro1027abe2008-07-30 04:13:04 -0400522 error = expand_files(files, fd);
523 if (error < 0)
524 goto out;
525
526 /*
527 * If we needed to expand the fs array we
528 * might have blocked - try again.
529 */
530 if (error)
531 goto repeat;
532
533 if (start <= files->next_fd)
534 files->next_fd = fd + 1;
535
David Howells1dce27c2012-02-16 17:49:42 +0000536 __set_open_fd(fd, fdt);
Al Viro1027abe2008-07-30 04:13:04 -0400537 if (flags & O_CLOEXEC)
David Howells1dce27c2012-02-16 17:49:42 +0000538 __set_close_on_exec(fd, fdt);
Al Viro1027abe2008-07-30 04:13:04 -0400539 else
David Howells1dce27c2012-02-16 17:49:42 +0000540 __clear_close_on_exec(fd, fdt);
Al Viro1027abe2008-07-30 04:13:04 -0400541 error = fd;
542#if 1
543 /* Sanity check */
Paul E. McKenneyadd1f092014-02-12 12:51:09 -0800544 if (rcu_access_pointer(fdt->fd[fd]) != NULL) {
Al Viro1027abe2008-07-30 04:13:04 -0400545 printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd);
546 rcu_assign_pointer(fdt->fd[fd], NULL);
547 }
548#endif
549
550out:
551 spin_unlock(&files->file_lock);
552 return error;
553}
554
Al Viroad47bd72012-08-21 20:11:34 -0400555static int alloc_fd(unsigned start, unsigned flags)
Al Virodcfadfa2012-08-12 17:27:30 -0400556{
557 return __alloc_fd(current->files, start, rlimit(RLIMIT_NOFILE), flags);
558}
559
Al Viro1a7bd222012-08-12 17:18:05 -0400560int get_unused_fd_flags(unsigned flags)
Al Viro1027abe2008-07-30 04:13:04 -0400561{
Al Virodcfadfa2012-08-12 17:27:30 -0400562 return __alloc_fd(current->files, 0, rlimit(RLIMIT_NOFILE), flags);
Al Viro1027abe2008-07-30 04:13:04 -0400563}
Al Viro1a7bd222012-08-12 17:18:05 -0400564EXPORT_SYMBOL(get_unused_fd_flags);
Al Viro56007ca2012-08-15 21:03:26 -0400565
566static void __put_unused_fd(struct files_struct *files, unsigned int fd)
567{
568 struct fdtable *fdt = files_fdtable(files);
569 __clear_open_fd(fd, fdt);
570 if (fd < files->next_fd)
571 files->next_fd = fd;
572}
573
574void put_unused_fd(unsigned int fd)
575{
576 struct files_struct *files = current->files;
577 spin_lock(&files->file_lock);
578 __put_unused_fd(files, fd);
579 spin_unlock(&files->file_lock);
580}
581
582EXPORT_SYMBOL(put_unused_fd);
583
584/*
585 * Install a file pointer in the fd array.
586 *
587 * The VFS is full of places where we drop the files lock between
588 * setting the open_fds bitmap and installing the file in the file
589 * array. At any such point, we are vulnerable to a dup2() race
590 * installing a file in the array before us. We need to detect this and
591 * fput() the struct file we are about to overwrite in this case.
592 *
593 * It should never happen - if we allow dup2() do it, _really_ bad things
594 * will follow.
Al Virof869e8a2012-08-15 21:06:33 -0400595 *
596 * NOTE: __fd_install() variant is really, really low-level; don't
597 * use it unless you are forced to by truly lousy API shoved down
598 * your throat. 'files' *MUST* be either current->files or obtained
599 * by get_files_struct(current) done by whoever had given it to you,
600 * or really bad things will happen. Normally you want to use
601 * fd_install() instead.
Al Viro56007ca2012-08-15 21:03:26 -0400602 */
603
Al Virof869e8a2012-08-15 21:06:33 -0400604void __fd_install(struct files_struct *files, unsigned int fd,
605 struct file *file)
Al Viro56007ca2012-08-15 21:03:26 -0400606{
Al Viro56007ca2012-08-15 21:03:26 -0400607 struct fdtable *fdt;
Eric Dumazet8a812522015-06-30 15:54:08 +0200608
609 might_sleep();
610 rcu_read_lock_sched();
611
612 while (unlikely(files->resize_in_progress)) {
613 rcu_read_unlock_sched();
614 wait_event(files->resize_wait, !files->resize_in_progress);
615 rcu_read_lock_sched();
616 }
617 /* coupled with smp_wmb() in expand_fdtable() */
618 smp_rmb();
619 fdt = rcu_dereference_sched(files->fdt);
Al Viro56007ca2012-08-15 21:03:26 -0400620 BUG_ON(fdt->fd[fd] != NULL);
621 rcu_assign_pointer(fdt->fd[fd], file);
Eric Dumazet8a812522015-06-30 15:54:08 +0200622 rcu_read_unlock_sched();
Al Viro56007ca2012-08-15 21:03:26 -0400623}
624
Al Virof869e8a2012-08-15 21:06:33 -0400625void fd_install(unsigned int fd, struct file *file)
626{
627 __fd_install(current->files, fd, file);
628}
629
Al Viro56007ca2012-08-15 21:03:26 -0400630EXPORT_SYMBOL(fd_install);
Al Viro0ee8cdf2012-08-15 21:12:10 -0400631
Al Viro483ce1d2012-08-19 12:04:24 -0400632/*
633 * The same warnings as for __alloc_fd()/__fd_install() apply here...
634 */
635int __close_fd(struct files_struct *files, unsigned fd)
636{
637 struct file *file;
638 struct fdtable *fdt;
639
640 spin_lock(&files->file_lock);
641 fdt = files_fdtable(files);
642 if (fd >= fdt->max_fds)
643 goto out_unlock;
644 file = fdt->fd[fd];
645 if (!file)
646 goto out_unlock;
647 rcu_assign_pointer(fdt->fd[fd], NULL);
648 __clear_close_on_exec(fd, fdt);
649 __put_unused_fd(files, fd);
650 spin_unlock(&files->file_lock);
651 return filp_close(file, files);
652
653out_unlock:
654 spin_unlock(&files->file_lock);
655 return -EBADF;
656}
657
Al Viro6a6d27d2012-08-21 09:56:33 -0400658void do_close_on_exec(struct files_struct *files)
659{
660 unsigned i;
661 struct fdtable *fdt;
662
663 /* exec unshares first */
Al Viro6a6d27d2012-08-21 09:56:33 -0400664 spin_lock(&files->file_lock);
665 for (i = 0; ; i++) {
666 unsigned long set;
667 unsigned fd = i * BITS_PER_LONG;
668 fdt = files_fdtable(files);
669 if (fd >= fdt->max_fds)
670 break;
671 set = fdt->close_on_exec[i];
672 if (!set)
673 continue;
674 fdt->close_on_exec[i] = 0;
675 for ( ; set ; fd++, set >>= 1) {
676 struct file *file;
677 if (!(set & 1))
678 continue;
679 file = fdt->fd[fd];
680 if (!file)
681 continue;
682 rcu_assign_pointer(fdt->fd[fd], NULL);
683 __put_unused_fd(files, fd);
684 spin_unlock(&files->file_lock);
685 filp_close(file, files);
686 cond_resched();
687 spin_lock(&files->file_lock);
688 }
689
690 }
691 spin_unlock(&files->file_lock);
692}
693
Oleg Nesterov1deb46e2014-01-13 16:48:19 +0100694static struct file *__fget(unsigned int fd, fmode_t mask)
Al Viro0ee8cdf2012-08-15 21:12:10 -0400695{
Al Viro0ee8cdf2012-08-15 21:12:10 -0400696 struct files_struct *files = current->files;
Oleg Nesterov1deb46e2014-01-13 16:48:19 +0100697 struct file *file;
Al Viro0ee8cdf2012-08-15 21:12:10 -0400698
699 rcu_read_lock();
Eric Dumazet5ba97d22015-06-29 17:10:30 +0200700loop:
Al Viro0ee8cdf2012-08-15 21:12:10 -0400701 file = fcheck_files(files, fd);
702 if (file) {
Eric Dumazet5ba97d22015-06-29 17:10:30 +0200703 /* File object ref couldn't be taken.
704 * dup2() atomicity guarantee is the reason
705 * we loop to catch the new file (or NULL pointer)
706 */
707 if (file->f_mode & mask)
Al Viro0ee8cdf2012-08-15 21:12:10 -0400708 file = NULL;
Eric Dumazet5ba97d22015-06-29 17:10:30 +0200709 else if (!get_file_rcu(file))
710 goto loop;
Al Viro0ee8cdf2012-08-15 21:12:10 -0400711 }
712 rcu_read_unlock();
713
714 return file;
715}
716
Oleg Nesterov1deb46e2014-01-13 16:48:19 +0100717struct file *fget(unsigned int fd)
718{
719 return __fget(fd, FMODE_PATH);
720}
Al Viro0ee8cdf2012-08-15 21:12:10 -0400721EXPORT_SYMBOL(fget);
722
723struct file *fget_raw(unsigned int fd)
724{
Oleg Nesterov1deb46e2014-01-13 16:48:19 +0100725 return __fget(fd, 0);
Al Viro0ee8cdf2012-08-15 21:12:10 -0400726}
Al Viro0ee8cdf2012-08-15 21:12:10 -0400727EXPORT_SYMBOL(fget_raw);
728
729/*
730 * Lightweight file lookup - no refcnt increment if fd table isn't shared.
731 *
732 * You can use this instead of fget if you satisfy all of the following
733 * conditions:
734 * 1) You must call fput_light before exiting the syscall and returning control
735 * to userspace (i.e. you cannot remember the returned struct file * after
736 * returning to userspace).
737 * 2) You must not call filp_close on the returned struct file * in between
738 * calls to fget_light and fput_light.
739 * 3) You must not clone the current task in between the calls to fget_light
740 * and fput_light.
741 *
742 * The fput_needed flag returned by fget_light should be passed to the
743 * corresponding fput_light.
744 */
Al Virobd2a31d2014-03-04 14:54:22 -0500745static unsigned long __fget_light(unsigned int fd, fmode_t mask)
Al Viro0ee8cdf2012-08-15 21:12:10 -0400746{
Al Viro0ee8cdf2012-08-15 21:12:10 -0400747 struct files_struct *files = current->files;
Oleg Nesterovad461832014-01-13 16:48:40 +0100748 struct file *file;
Al Viro0ee8cdf2012-08-15 21:12:10 -0400749
Al Viro0ee8cdf2012-08-15 21:12:10 -0400750 if (atomic_read(&files->count) == 1) {
Oleg Nesterova8d4b832014-01-11 19:19:32 +0100751 file = __fcheck_files(files, fd);
Al Virobd2a31d2014-03-04 14:54:22 -0500752 if (!file || unlikely(file->f_mode & mask))
753 return 0;
754 return (unsigned long)file;
Al Viro0ee8cdf2012-08-15 21:12:10 -0400755 } else {
Oleg Nesterove6ff9a92014-01-13 16:49:06 +0100756 file = __fget(fd, mask);
Al Virobd2a31d2014-03-04 14:54:22 -0500757 if (!file)
758 return 0;
759 return FDPUT_FPUT | (unsigned long)file;
Al Viro0ee8cdf2012-08-15 21:12:10 -0400760 }
Al Viro0ee8cdf2012-08-15 21:12:10 -0400761}
Al Virobd2a31d2014-03-04 14:54:22 -0500762unsigned long __fdget(unsigned int fd)
Oleg Nesterovad461832014-01-13 16:48:40 +0100763{
Al Virobd2a31d2014-03-04 14:54:22 -0500764 return __fget_light(fd, FMODE_PATH);
Oleg Nesterovad461832014-01-13 16:48:40 +0100765}
Al Virobd2a31d2014-03-04 14:54:22 -0500766EXPORT_SYMBOL(__fdget);
Al Viro0ee8cdf2012-08-15 21:12:10 -0400767
Al Virobd2a31d2014-03-04 14:54:22 -0500768unsigned long __fdget_raw(unsigned int fd)
Al Viro0ee8cdf2012-08-15 21:12:10 -0400769{
Al Virobd2a31d2014-03-04 14:54:22 -0500770 return __fget_light(fd, 0);
Al Viro0ee8cdf2012-08-15 21:12:10 -0400771}
Al Virofe17f222012-08-21 11:48:11 -0400772
Al Virobd2a31d2014-03-04 14:54:22 -0500773unsigned long __fdget_pos(unsigned int fd)
774{
Eric Biggers99aea682014-03-16 15:47:48 -0500775 unsigned long v = __fdget(fd);
776 struct file *file = (struct file *)(v & ~3);
Al Virobd2a31d2014-03-04 14:54:22 -0500777
Eric Biggers99aea682014-03-16 15:47:48 -0500778 if (file && (file->f_mode & FMODE_ATOMIC_POS)) {
Al Virobd2a31d2014-03-04 14:54:22 -0500779 if (file_count(file) > 1) {
780 v |= FDPUT_POS_UNLOCK;
781 mutex_lock(&file->f_pos_lock);
782 }
783 }
Eric Biggers99aea682014-03-16 15:47:48 -0500784 return v;
Al Virobd2a31d2014-03-04 14:54:22 -0500785}
786
787/*
788 * We only lock f_pos if we have threads or if the file might be
789 * shared with another process. In both cases we'll have an elevated
790 * file count (done either by fdget() or by fork()).
791 */
792
Al Virofe17f222012-08-21 11:48:11 -0400793void set_close_on_exec(unsigned int fd, int flag)
794{
795 struct files_struct *files = current->files;
796 struct fdtable *fdt;
797 spin_lock(&files->file_lock);
798 fdt = files_fdtable(files);
799 if (flag)
800 __set_close_on_exec(fd, fdt);
801 else
802 __clear_close_on_exec(fd, fdt);
803 spin_unlock(&files->file_lock);
804}
805
806bool get_close_on_exec(unsigned int fd)
807{
808 struct files_struct *files = current->files;
809 struct fdtable *fdt;
810 bool res;
811 rcu_read_lock();
812 fdt = files_fdtable(files);
813 res = close_on_exec(fd, fdt);
814 rcu_read_unlock();
815 return res;
816}
817
Al Viro8280d162012-08-21 12:11:46 -0400818static int do_dup2(struct files_struct *files,
819 struct file *file, unsigned fd, unsigned flags)
Al Viroe9830942014-08-31 14:12:09 -0400820__releases(&files->file_lock)
Al Viro8280d162012-08-21 12:11:46 -0400821{
822 struct file *tofree;
823 struct fdtable *fdt;
824
825 /*
826 * We need to detect attempts to do dup2() over allocated but still
827 * not finished descriptor. NB: OpenBSD avoids that at the price of
828 * extra work in their equivalent of fget() - they insert struct
829 * file immediately after grabbing descriptor, mark it larval if
830 * more work (e.g. actual opening) is needed and make sure that
831 * fget() treats larval files as absent. Potentially interesting,
832 * but while extra work in fget() is trivial, locking implications
833 * and amount of surgery on open()-related paths in VFS are not.
834 * FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
835 * deadlocks in rather amusing ways, AFAICS. All of that is out of
836 * scope of POSIX or SUS, since neither considers shared descriptor
837 * tables and this condition does not arise without those.
838 */
839 fdt = files_fdtable(files);
840 tofree = fdt->fd[fd];
841 if (!tofree && fd_is_open(fd, fdt))
842 goto Ebusy;
843 get_file(file);
844 rcu_assign_pointer(fdt->fd[fd], file);
845 __set_open_fd(fd, fdt);
846 if (flags & O_CLOEXEC)
847 __set_close_on_exec(fd, fdt);
848 else
849 __clear_close_on_exec(fd, fdt);
850 spin_unlock(&files->file_lock);
851
852 if (tofree)
853 filp_close(tofree, files);
854
855 return fd;
856
857Ebusy:
858 spin_unlock(&files->file_lock);
859 return -EBUSY;
860}
861
862int replace_fd(unsigned fd, struct file *file, unsigned flags)
863{
864 int err;
865 struct files_struct *files = current->files;
866
867 if (!file)
868 return __close_fd(files, fd);
869
870 if (fd >= rlimit(RLIMIT_NOFILE))
Al Viro08f05c42012-10-31 03:37:48 +0000871 return -EBADF;
Al Viro8280d162012-08-21 12:11:46 -0400872
873 spin_lock(&files->file_lock);
874 err = expand_files(files, fd);
875 if (unlikely(err < 0))
876 goto out_unlock;
877 return do_dup2(files, file, fd, flags);
878
879out_unlock:
880 spin_unlock(&files->file_lock);
881 return err;
882}
883
Al Virofe17f222012-08-21 11:48:11 -0400884SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags)
885{
886 int err = -EBADF;
Al Viro8280d162012-08-21 12:11:46 -0400887 struct file *file;
888 struct files_struct *files = current->files;
Al Virofe17f222012-08-21 11:48:11 -0400889
890 if ((flags & ~O_CLOEXEC) != 0)
891 return -EINVAL;
892
Richard W.M. Jonesaed97642012-10-09 15:27:43 +0100893 if (unlikely(oldfd == newfd))
894 return -EINVAL;
895
Al Virofe17f222012-08-21 11:48:11 -0400896 if (newfd >= rlimit(RLIMIT_NOFILE))
Al Viro08f05c42012-10-31 03:37:48 +0000897 return -EBADF;
Al Virofe17f222012-08-21 11:48:11 -0400898
899 spin_lock(&files->file_lock);
900 err = expand_files(files, newfd);
901 file = fcheck(oldfd);
902 if (unlikely(!file))
903 goto Ebadf;
904 if (unlikely(err < 0)) {
905 if (err == -EMFILE)
906 goto Ebadf;
907 goto out_unlock;
908 }
Al Viro8280d162012-08-21 12:11:46 -0400909 return do_dup2(files, file, newfd, flags);
Al Virofe17f222012-08-21 11:48:11 -0400910
911Ebadf:
912 err = -EBADF;
913out_unlock:
914 spin_unlock(&files->file_lock);
915 return err;
916}
917
918SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd)
919{
920 if (unlikely(newfd == oldfd)) { /* corner case */
921 struct files_struct *files = current->files;
922 int retval = oldfd;
923
924 rcu_read_lock();
925 if (!fcheck_files(files, oldfd))
926 retval = -EBADF;
927 rcu_read_unlock();
928 return retval;
929 }
930 return sys_dup3(oldfd, newfd, 0);
931}
932
933SYSCALL_DEFINE1(dup, unsigned int, fildes)
934{
935 int ret = -EBADF;
936 struct file *file = fget_raw(fildes);
937
938 if (file) {
Yann Droneaud8d10a032014-12-10 15:45:44 -0800939 ret = get_unused_fd_flags(0);
Al Virofe17f222012-08-21 11:48:11 -0400940 if (ret >= 0)
941 fd_install(ret, file);
942 else
943 fput(file);
944 }
945 return ret;
946}
947
948int f_dupfd(unsigned int from, struct file *file, unsigned flags)
949{
950 int err;
951 if (from >= rlimit(RLIMIT_NOFILE))
952 return -EINVAL;
953 err = alloc_fd(from, flags);
954 if (err >= 0) {
955 get_file(file);
956 fd_install(err, file);
957 }
958 return err;
959}
Al Viroc3c073f2012-08-21 22:32:06 -0400960
961int iterate_fd(struct files_struct *files, unsigned n,
962 int (*f)(const void *, struct file *, unsigned),
963 const void *p)
964{
965 struct fdtable *fdt;
Al Viroc3c073f2012-08-21 22:32:06 -0400966 int res = 0;
967 if (!files)
968 return 0;
969 spin_lock(&files->file_lock);
Al Viroa77cfcb2012-11-29 22:57:33 -0500970 for (fdt = files_fdtable(files); n < fdt->max_fds; n++) {
971 struct file *file;
972 file = rcu_dereference_check_fdtable(files, fdt->fd[n]);
973 if (!file)
974 continue;
975 res = f(p, file, n);
976 if (res)
977 break;
Al Viroc3c073f2012-08-21 22:32:06 -0400978 }
979 spin_unlock(&files->file_lock);
980 return res;
981}
982EXPORT_SYMBOL(iterate_fd);