Commit | Line | Data |
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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 LT |
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 | ||
fe17f22d | 10 | #include <linux/syscalls.h> |
630d9c47 | 11 | #include <linux/export.h> |
1da177e4 | 12 | #include <linux/fs.h> |
278a5fba | 13 | #include <linux/kernel.h> |
1da177e4 | 14 | #include <linux/mm.h> |
3f07c014 | 15 | #include <linux/sched/signal.h> |
1da177e4 | 16 | #include <linux/slab.h> |
1da177e4 | 17 | #include <linux/file.h> |
9f3acc31 | 18 | #include <linux/fdtable.h> |
1da177e4 | 19 | #include <linux/bitops.h> |
ab2af1f5 DS |
20 | #include <linux/spinlock.h> |
21 | #include <linux/rcupdate.h> | |
60997c3d | 22 | #include <linux/close_range.h> |
66590610 | 23 | #include <net/sock.h> |
ab2af1f5 | 24 | |
53dec2ea JA |
25 | #include "internal.h" |
26 | ||
9b80a184 AD |
27 | unsigned int sysctl_nr_open __read_mostly = 1024*1024; |
28 | unsigned int sysctl_nr_open_min = BITS_PER_LONG; | |
752343be RV |
29 | /* our min() is unusable in constant expressions ;-/ */ |
30 | #define __const_min(x, y) ((x) < (y) ? (x) : (y)) | |
9b80a184 AD |
31 | unsigned int sysctl_nr_open_max = |
32 | __const_min(INT_MAX, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG; | |
9cfe015a | 33 | |
a892e2d7 | 34 | static void __free_fdtable(struct fdtable *fdt) |
1da177e4 | 35 | { |
f6c0a192 AV |
36 | kvfree(fdt->fd); |
37 | kvfree(fdt->open_fds); | |
a892e2d7 | 38 | kfree(fdt); |
ab2af1f5 | 39 | } |
1da177e4 | 40 | |
7cf4dc3c | 41 | static void free_fdtable_rcu(struct rcu_head *rcu) |
ab2af1f5 | 42 | { |
ac3e3c5b | 43 | __free_fdtable(container_of(rcu, struct fdtable, rcu)); |
ab2af1f5 DS |
44 | } |
45 | ||
f3f86e33 LT |
46 | #define BITBIT_NR(nr) BITS_TO_LONGS(BITS_TO_LONGS(nr)) |
47 | #define BITBIT_SIZE(nr) (BITBIT_NR(nr) * sizeof(long)) | |
48 | ||
ab2af1f5 | 49 | /* |
ea5c58e7 EB |
50 | * Copy 'count' fd bits from the old table to the new table and clear the extra |
51 | * space if any. This does not copy the file pointers. Called with the files | |
52 | * spinlock held for write. | |
53 | */ | |
54 | static void copy_fd_bitmaps(struct fdtable *nfdt, struct fdtable *ofdt, | |
55 | unsigned int count) | |
56 | { | |
57 | unsigned int cpy, set; | |
58 | ||
59 | cpy = count / BITS_PER_BYTE; | |
60 | set = (nfdt->max_fds - count) / BITS_PER_BYTE; | |
61 | memcpy(nfdt->open_fds, ofdt->open_fds, cpy); | |
62 | memset((char *)nfdt->open_fds + cpy, 0, set); | |
63 | memcpy(nfdt->close_on_exec, ofdt->close_on_exec, cpy); | |
64 | memset((char *)nfdt->close_on_exec + cpy, 0, set); | |
65 | ||
66 | cpy = BITBIT_SIZE(count); | |
67 | set = BITBIT_SIZE(nfdt->max_fds) - cpy; | |
68 | memcpy(nfdt->full_fds_bits, ofdt->full_fds_bits, cpy); | |
69 | memset((char *)nfdt->full_fds_bits + cpy, 0, set); | |
70 | } | |
71 | ||
72 | /* | |
73 | * Copy all file descriptors from the old table to the new, expanded table and | |
74 | * clear the extra space. Called with the files spinlock held for write. | |
ab2af1f5 | 75 | */ |
5466b456 | 76 | static void copy_fdtable(struct fdtable *nfdt, struct fdtable *ofdt) |
ab2af1f5 | 77 | { |
4e89b721 | 78 | size_t cpy, set; |
ab2af1f5 | 79 | |
5466b456 | 80 | BUG_ON(nfdt->max_fds < ofdt->max_fds); |
5466b456 VL |
81 | |
82 | cpy = ofdt->max_fds * sizeof(struct file *); | |
83 | set = (nfdt->max_fds - ofdt->max_fds) * sizeof(struct file *); | |
84 | memcpy(nfdt->fd, ofdt->fd, cpy); | |
ea5c58e7 | 85 | memset((char *)nfdt->fd + cpy, 0, set); |
5466b456 | 86 | |
ea5c58e7 | 87 | copy_fd_bitmaps(nfdt, ofdt, ofdt->max_fds); |
1da177e4 LT |
88 | } |
89 | ||
1c24a186 LT |
90 | /* |
91 | * Note how the fdtable bitmap allocations very much have to be a multiple of | |
92 | * BITS_PER_LONG. This is not only because we walk those things in chunks of | |
93 | * 'unsigned long' in some places, but simply because that is how the Linux | |
94 | * kernel bitmaps are defined to work: they are not "bits in an array of bytes", | |
95 | * they are very much "bits in an array of unsigned long". | |
96 | * | |
97 | * The ALIGN(nr, BITS_PER_LONG) here is for clarity: since we just multiplied | |
98 | * by that "1024/sizeof(ptr)" before, we already know there are sufficient | |
99 | * clear low bits. Clang seems to realize that, gcc ends up being confused. | |
100 | * | |
101 | * On a 128-bit machine, the ALIGN() would actually matter. In the meantime, | |
102 | * let's consider it documentation (and maybe a test-case for gcc to improve | |
103 | * its code generation ;) | |
104 | */ | |
5466b456 | 105 | static struct fdtable * alloc_fdtable(unsigned int nr) |
1da177e4 | 106 | { |
5466b456 | 107 | struct fdtable *fdt; |
1fd36adc | 108 | void *data; |
1da177e4 | 109 | |
ab2af1f5 | 110 | /* |
5466b456 VL |
111 | * Figure out how many fds we actually want to support in this fdtable. |
112 | * Allocation steps are keyed to the size of the fdarray, since it | |
113 | * grows far faster than any of the other dynamic data. We try to fit | |
114 | * the fdarray into comfortable page-tuned chunks: starting at 1024B | |
115 | * and growing in powers of two from there on. | |
ab2af1f5 | 116 | */ |
5466b456 VL |
117 | nr /= (1024 / sizeof(struct file *)); |
118 | nr = roundup_pow_of_two(nr + 1); | |
119 | nr *= (1024 / sizeof(struct file *)); | |
1c24a186 | 120 | nr = ALIGN(nr, BITS_PER_LONG); |
5c598b34 AV |
121 | /* |
122 | * Note that this can drive nr *below* what we had passed if sysctl_nr_open | |
123 | * had been set lower between the check in expand_files() and here. Deal | |
124 | * with that in caller, it's cheaper that way. | |
125 | * | |
126 | * We make sure that nr remains a multiple of BITS_PER_LONG - otherwise | |
127 | * bitmaps handling below becomes unpleasant, to put it mildly... | |
128 | */ | |
129 | if (unlikely(nr > sysctl_nr_open)) | |
130 | nr = ((sysctl_nr_open - 1) | (BITS_PER_LONG - 1)) + 1; | |
bbea9f69 | 131 | |
5d097056 | 132 | fdt = kmalloc(sizeof(struct fdtable), GFP_KERNEL_ACCOUNT); |
5466b456 | 133 | if (!fdt) |
bbea9f69 | 134 | goto out; |
5466b456 | 135 | fdt->max_fds = nr; |
c823bd92 | 136 | data = kvmalloc_array(nr, sizeof(struct file *), GFP_KERNEL_ACCOUNT); |
5466b456 VL |
137 | if (!data) |
138 | goto out_fdt; | |
1fd36adc DH |
139 | fdt->fd = data; |
140 | ||
c823bd92 MH |
141 | data = kvmalloc(max_t(size_t, |
142 | 2 * nr / BITS_PER_BYTE + BITBIT_SIZE(nr), L1_CACHE_BYTES), | |
143 | GFP_KERNEL_ACCOUNT); | |
5466b456 VL |
144 | if (!data) |
145 | goto out_arr; | |
1fd36adc | 146 | fdt->open_fds = data; |
5466b456 | 147 | data += nr / BITS_PER_BYTE; |
1fd36adc | 148 | fdt->close_on_exec = data; |
f3f86e33 LT |
149 | data += nr / BITS_PER_BYTE; |
150 | fdt->full_fds_bits = data; | |
5466b456 | 151 | |
ab2af1f5 | 152 | return fdt; |
5466b456 VL |
153 | |
154 | out_arr: | |
f6c0a192 | 155 | kvfree(fdt->fd); |
5466b456 | 156 | out_fdt: |
ab2af1f5 | 157 | kfree(fdt); |
5466b456 | 158 | out: |
ab2af1f5 DS |
159 | return NULL; |
160 | } | |
1da177e4 | 161 | |
ab2af1f5 | 162 | /* |
74d392aa VL |
163 | * Expand the file descriptor table. |
164 | * This function will allocate a new fdtable and both fd array and fdset, of | |
165 | * the given size. | |
166 | * Return <0 error code on error; 1 on successful completion. | |
167 | * The files->file_lock should be held on entry, and will be held on exit. | |
ab2af1f5 | 168 | */ |
9b80a184 | 169 | static int expand_fdtable(struct files_struct *files, unsigned int nr) |
ab2af1f5 DS |
170 | __releases(files->file_lock) |
171 | __acquires(files->file_lock) | |
172 | { | |
74d392aa | 173 | struct fdtable *new_fdt, *cur_fdt; |
ab2af1f5 DS |
174 | |
175 | spin_unlock(&files->file_lock); | |
74d392aa | 176 | new_fdt = alloc_fdtable(nr); |
8a81252b | 177 | |
d74ba04d | 178 | /* make sure all fd_install() have seen resize_in_progress |
8a81252b ED |
179 | * or have finished their rcu_read_lock_sched() section. |
180 | */ | |
181 | if (atomic_read(&files->count) > 1) | |
c93ffc15 | 182 | synchronize_rcu(); |
8a81252b | 183 | |
ab2af1f5 | 184 | spin_lock(&files->file_lock); |
74d392aa VL |
185 | if (!new_fdt) |
186 | return -ENOMEM; | |
5c598b34 AV |
187 | /* |
188 | * extremely unlikely race - sysctl_nr_open decreased between the check in | |
189 | * caller and alloc_fdtable(). Cheaper to catch it here... | |
190 | */ | |
191 | if (unlikely(new_fdt->max_fds <= nr)) { | |
a892e2d7 | 192 | __free_fdtable(new_fdt); |
5c598b34 AV |
193 | return -EMFILE; |
194 | } | |
74d392aa | 195 | cur_fdt = files_fdtable(files); |
8a81252b ED |
196 | BUG_ON(nr < cur_fdt->max_fds); |
197 | copy_fdtable(new_fdt, cur_fdt); | |
198 | rcu_assign_pointer(files->fdt, new_fdt); | |
199 | if (cur_fdt != &files->fdtab) | |
200 | call_rcu(&cur_fdt->rcu, free_fdtable_rcu); | |
d74ba04d | 201 | /* coupled with smp_rmb() in fd_install() */ |
8a81252b | 202 | smp_wmb(); |
74d392aa | 203 | return 1; |
1da177e4 LT |
204 | } |
205 | ||
206 | /* | |
207 | * Expand files. | |
74d392aa VL |
208 | * This function will expand the file structures, if the requested size exceeds |
209 | * the current capacity and there is room for expansion. | |
210 | * Return <0 error code on error; 0 when nothing done; 1 when files were | |
211 | * expanded and execution may have blocked. | |
212 | * The files->file_lock should be held on entry, and will be held on exit. | |
1da177e4 | 213 | */ |
9b80a184 | 214 | static int expand_files(struct files_struct *files, unsigned int nr) |
8a81252b ED |
215 | __releases(files->file_lock) |
216 | __acquires(files->file_lock) | |
1da177e4 | 217 | { |
badf1662 | 218 | struct fdtable *fdt; |
8a81252b | 219 | int expanded = 0; |
1da177e4 | 220 | |
8a81252b | 221 | repeat: |
badf1662 | 222 | fdt = files_fdtable(files); |
4e1e018e | 223 | |
74d392aa | 224 | /* Do we need to expand? */ |
bbea9f69 | 225 | if (nr < fdt->max_fds) |
8a81252b | 226 | return expanded; |
4e1e018e | 227 | |
74d392aa | 228 | /* Can we expand? */ |
9cfe015a | 229 | if (nr >= sysctl_nr_open) |
74d392aa VL |
230 | return -EMFILE; |
231 | ||
8a81252b ED |
232 | if (unlikely(files->resize_in_progress)) { |
233 | spin_unlock(&files->file_lock); | |
234 | expanded = 1; | |
235 | wait_event(files->resize_wait, !files->resize_in_progress); | |
236 | spin_lock(&files->file_lock); | |
237 | goto repeat; | |
238 | } | |
239 | ||
74d392aa | 240 | /* All good, so we try */ |
8a81252b ED |
241 | files->resize_in_progress = true; |
242 | expanded = expand_fdtable(files, nr); | |
243 | files->resize_in_progress = false; | |
244 | ||
245 | wake_up_all(&files->resize_wait); | |
246 | return expanded; | |
1da177e4 | 247 | } |
ab2af1f5 | 248 | |
9b80a184 | 249 | static inline void __set_close_on_exec(unsigned int fd, struct fdtable *fdt) |
b8318b01 AV |
250 | { |
251 | __set_bit(fd, fdt->close_on_exec); | |
252 | } | |
253 | ||
9b80a184 | 254 | static inline void __clear_close_on_exec(unsigned int fd, struct fdtable *fdt) |
b8318b01 | 255 | { |
fc90888d LT |
256 | if (test_bit(fd, fdt->close_on_exec)) |
257 | __clear_bit(fd, fdt->close_on_exec); | |
b8318b01 AV |
258 | } |
259 | ||
f3f86e33 | 260 | static inline void __set_open_fd(unsigned int fd, struct fdtable *fdt) |
b8318b01 AV |
261 | { |
262 | __set_bit(fd, fdt->open_fds); | |
f3f86e33 LT |
263 | fd /= BITS_PER_LONG; |
264 | if (!~fdt->open_fds[fd]) | |
265 | __set_bit(fd, fdt->full_fds_bits); | |
b8318b01 AV |
266 | } |
267 | ||
f3f86e33 | 268 | static inline void __clear_open_fd(unsigned int fd, struct fdtable *fdt) |
b8318b01 AV |
269 | { |
270 | __clear_bit(fd, fdt->open_fds); | |
f3f86e33 | 271 | __clear_bit(fd / BITS_PER_LONG, fdt->full_fds_bits); |
b8318b01 AV |
272 | } |
273 | ||
9b80a184 | 274 | static unsigned int count_open_files(struct fdtable *fdt) |
02afc626 | 275 | { |
9b80a184 AD |
276 | unsigned int size = fdt->max_fds; |
277 | unsigned int i; | |
02afc626 AV |
278 | |
279 | /* Find the last open fd */ | |
1fd36adc DH |
280 | for (i = size / BITS_PER_LONG; i > 0; ) { |
281 | if (fdt->open_fds[--i]) | |
02afc626 AV |
282 | break; |
283 | } | |
1fd36adc | 284 | i = (i + 1) * BITS_PER_LONG; |
02afc626 AV |
285 | return i; |
286 | } | |
287 | ||
1c24a186 LT |
288 | /* |
289 | * Note that a sane fdtable size always has to be a multiple of | |
290 | * BITS_PER_LONG, since we have bitmaps that are sized by this. | |
291 | * | |
292 | * 'max_fds' will normally already be properly aligned, but it | |
293 | * turns out that in the close_range() -> __close_range() -> | |
294 | * unshare_fd() -> dup_fd() -> sane_fdtable_size() we can end | |
295 | * up having a 'max_fds' value that isn't already aligned. | |
296 | * | |
297 | * Rather than make close_range() have to worry about this, | |
298 | * just make that BITS_PER_LONG alignment be part of a sane | |
299 | * fdtable size. Becuase that's really what it is. | |
300 | */ | |
60997c3d CB |
301 | static unsigned int sane_fdtable_size(struct fdtable *fdt, unsigned int max_fds) |
302 | { | |
303 | unsigned int count; | |
304 | ||
305 | count = count_open_files(fdt); | |
306 | if (max_fds < NR_OPEN_DEFAULT) | |
307 | max_fds = NR_OPEN_DEFAULT; | |
d888c83f | 308 | return ALIGN(min(count, max_fds), BITS_PER_LONG); |
60997c3d CB |
309 | } |
310 | ||
02afc626 AV |
311 | /* |
312 | * Allocate a new files structure and copy contents from the | |
313 | * passed in files structure. | |
314 | * errorp will be valid only when the returned files_struct is NULL. | |
315 | */ | |
60997c3d | 316 | struct files_struct *dup_fd(struct files_struct *oldf, unsigned int max_fds, int *errorp) |
02afc626 AV |
317 | { |
318 | struct files_struct *newf; | |
319 | struct file **old_fds, **new_fds; | |
9b80a184 | 320 | unsigned int open_files, i; |
02afc626 AV |
321 | struct fdtable *old_fdt, *new_fdt; |
322 | ||
323 | *errorp = -ENOMEM; | |
afbec7ff | 324 | newf = kmem_cache_alloc(files_cachep, GFP_KERNEL); |
02afc626 AV |
325 | if (!newf) |
326 | goto out; | |
327 | ||
afbec7ff AV |
328 | atomic_set(&newf->count, 1); |
329 | ||
330 | spin_lock_init(&newf->file_lock); | |
8a81252b ED |
331 | newf->resize_in_progress = false; |
332 | init_waitqueue_head(&newf->resize_wait); | |
afbec7ff AV |
333 | newf->next_fd = 0; |
334 | new_fdt = &newf->fdtab; | |
335 | new_fdt->max_fds = NR_OPEN_DEFAULT; | |
1fd36adc DH |
336 | new_fdt->close_on_exec = newf->close_on_exec_init; |
337 | new_fdt->open_fds = newf->open_fds_init; | |
f3f86e33 | 338 | new_fdt->full_fds_bits = newf->full_fds_bits_init; |
afbec7ff | 339 | new_fdt->fd = &newf->fd_array[0]; |
afbec7ff | 340 | |
02afc626 AV |
341 | spin_lock(&oldf->file_lock); |
342 | old_fdt = files_fdtable(oldf); | |
60997c3d | 343 | open_files = sane_fdtable_size(old_fdt, max_fds); |
02afc626 AV |
344 | |
345 | /* | |
346 | * Check whether we need to allocate a larger fd array and fd set. | |
02afc626 | 347 | */ |
adbecb12 | 348 | while (unlikely(open_files > new_fdt->max_fds)) { |
02afc626 | 349 | spin_unlock(&oldf->file_lock); |
9dec3c4d | 350 | |
a892e2d7 CG |
351 | if (new_fdt != &newf->fdtab) |
352 | __free_fdtable(new_fdt); | |
adbecb12 | 353 | |
9dec3c4d AV |
354 | new_fdt = alloc_fdtable(open_files - 1); |
355 | if (!new_fdt) { | |
356 | *errorp = -ENOMEM; | |
357 | goto out_release; | |
358 | } | |
359 | ||
360 | /* beyond sysctl_nr_open; nothing to do */ | |
361 | if (unlikely(new_fdt->max_fds < open_files)) { | |
a892e2d7 | 362 | __free_fdtable(new_fdt); |
9dec3c4d | 363 | *errorp = -EMFILE; |
02afc626 | 364 | goto out_release; |
9dec3c4d | 365 | } |
9dec3c4d | 366 | |
02afc626 AV |
367 | /* |
368 | * Reacquire the oldf lock and a pointer to its fd table | |
369 | * who knows it may have a new bigger fd table. We need | |
370 | * the latest pointer. | |
371 | */ | |
372 | spin_lock(&oldf->file_lock); | |
373 | old_fdt = files_fdtable(oldf); | |
60997c3d | 374 | open_files = sane_fdtable_size(old_fdt, max_fds); |
02afc626 AV |
375 | } |
376 | ||
ea5c58e7 EB |
377 | copy_fd_bitmaps(new_fdt, old_fdt, open_files); |
378 | ||
02afc626 AV |
379 | old_fds = old_fdt->fd; |
380 | new_fds = new_fdt->fd; | |
381 | ||
02afc626 AV |
382 | for (i = open_files; i != 0; i--) { |
383 | struct file *f = *old_fds++; | |
384 | if (f) { | |
385 | get_file(f); | |
386 | } else { | |
387 | /* | |
388 | * The fd may be claimed in the fd bitmap but not yet | |
389 | * instantiated in the files array if a sibling thread | |
390 | * is partway through open(). So make sure that this | |
391 | * fd is available to the new process. | |
392 | */ | |
1dce27c5 | 393 | __clear_open_fd(open_files - i, new_fdt); |
02afc626 AV |
394 | } |
395 | rcu_assign_pointer(*new_fds++, f); | |
396 | } | |
397 | spin_unlock(&oldf->file_lock); | |
398 | ||
ea5c58e7 EB |
399 | /* clear the remainder */ |
400 | memset(new_fds, 0, (new_fdt->max_fds - open_files) * sizeof(struct file *)); | |
02afc626 | 401 | |
afbec7ff AV |
402 | rcu_assign_pointer(newf->fdt, new_fdt); |
403 | ||
02afc626 AV |
404 | return newf; |
405 | ||
406 | out_release: | |
407 | kmem_cache_free(files_cachep, newf); | |
408 | out: | |
409 | return NULL; | |
410 | } | |
411 | ||
ce08b62d | 412 | static struct fdtable *close_files(struct files_struct * files) |
7cf4dc3c | 413 | { |
7cf4dc3c AV |
414 | /* |
415 | * It is safe to dereference the fd table without RCU or | |
416 | * ->file_lock because this is the last reference to the | |
ce08b62d | 417 | * files structure. |
7cf4dc3c | 418 | */ |
ce08b62d | 419 | struct fdtable *fdt = rcu_dereference_raw(files->fdt); |
9b80a184 | 420 | unsigned int i, j = 0; |
ce08b62d | 421 | |
7cf4dc3c AV |
422 | for (;;) { |
423 | unsigned long set; | |
424 | i = j * BITS_PER_LONG; | |
425 | if (i >= fdt->max_fds) | |
426 | break; | |
427 | set = fdt->open_fds[j++]; | |
428 | while (set) { | |
429 | if (set & 1) { | |
430 | struct file * file = xchg(&fdt->fd[i], NULL); | |
431 | if (file) { | |
432 | filp_close(file, files); | |
388a4c88 | 433 | cond_resched(); |
7cf4dc3c AV |
434 | } |
435 | } | |
436 | i++; | |
437 | set >>= 1; | |
438 | } | |
439 | } | |
ce08b62d ON |
440 | |
441 | return fdt; | |
7cf4dc3c AV |
442 | } |
443 | ||
7cf4dc3c AV |
444 | void put_files_struct(struct files_struct *files) |
445 | { | |
7cf4dc3c | 446 | if (atomic_dec_and_test(&files->count)) { |
ce08b62d ON |
447 | struct fdtable *fdt = close_files(files); |
448 | ||
b9e02af0 AV |
449 | /* free the arrays if they are not embedded */ |
450 | if (fdt != &files->fdtab) | |
451 | __free_fdtable(fdt); | |
452 | kmem_cache_free(files_cachep, files); | |
7cf4dc3c AV |
453 | } |
454 | } | |
455 | ||
7cf4dc3c AV |
456 | void exit_files(struct task_struct *tsk) |
457 | { | |
458 | struct files_struct * files = tsk->files; | |
459 | ||
460 | if (files) { | |
461 | task_lock(tsk); | |
462 | tsk->files = NULL; | |
463 | task_unlock(tsk); | |
464 | put_files_struct(files); | |
465 | } | |
466 | } | |
467 | ||
f52111b1 AV |
468 | struct files_struct init_files = { |
469 | .count = ATOMIC_INIT(1), | |
470 | .fdt = &init_files.fdtab, | |
471 | .fdtab = { | |
472 | .max_fds = NR_OPEN_DEFAULT, | |
473 | .fd = &init_files.fd_array[0], | |
1fd36adc DH |
474 | .close_on_exec = init_files.close_on_exec_init, |
475 | .open_fds = init_files.open_fds_init, | |
f3f86e33 | 476 | .full_fds_bits = init_files.full_fds_bits_init, |
f52111b1 | 477 | }, |
eece09ec | 478 | .file_lock = __SPIN_LOCK_UNLOCKED(init_files.file_lock), |
5704a068 | 479 | .resize_wait = __WAIT_QUEUE_HEAD_INITIALIZER(init_files.resize_wait), |
f52111b1 | 480 | }; |
1027abe8 | 481 | |
9b80a184 | 482 | static unsigned int find_next_fd(struct fdtable *fdt, unsigned int start) |
f3f86e33 | 483 | { |
9b80a184 AD |
484 | unsigned int maxfd = fdt->max_fds; |
485 | unsigned int maxbit = maxfd / BITS_PER_LONG; | |
486 | unsigned int bitbit = start / BITS_PER_LONG; | |
f3f86e33 LT |
487 | |
488 | bitbit = find_next_zero_bit(fdt->full_fds_bits, maxbit, bitbit) * BITS_PER_LONG; | |
489 | if (bitbit > maxfd) | |
490 | return maxfd; | |
491 | if (bitbit > start) | |
492 | start = bitbit; | |
493 | return find_next_zero_bit(fdt->open_fds, maxfd, start); | |
494 | } | |
495 | ||
1027abe8 AV |
496 | /* |
497 | * allocate a file descriptor, mark it busy. | |
498 | */ | |
aa384d10 | 499 | static int alloc_fd(unsigned start, unsigned end, unsigned flags) |
1027abe8 | 500 | { |
aa384d10 | 501 | struct files_struct *files = current->files; |
1027abe8 AV |
502 | unsigned int fd; |
503 | int error; | |
504 | struct fdtable *fdt; | |
505 | ||
506 | spin_lock(&files->file_lock); | |
507 | repeat: | |
508 | fdt = files_fdtable(files); | |
509 | fd = start; | |
510 | if (fd < files->next_fd) | |
511 | fd = files->next_fd; | |
512 | ||
513 | if (fd < fdt->max_fds) | |
f3f86e33 | 514 | fd = find_next_fd(fdt, fd); |
1027abe8 | 515 | |
f33ff992 AV |
516 | /* |
517 | * N.B. For clone tasks sharing a files structure, this test | |
518 | * will limit the total number of files that can be opened. | |
519 | */ | |
520 | error = -EMFILE; | |
521 | if (fd >= end) | |
522 | goto out; | |
523 | ||
1027abe8 AV |
524 | error = expand_files(files, fd); |
525 | if (error < 0) | |
526 | goto out; | |
527 | ||
528 | /* | |
529 | * If we needed to expand the fs array we | |
530 | * might have blocked - try again. | |
531 | */ | |
532 | if (error) | |
533 | goto repeat; | |
534 | ||
535 | if (start <= files->next_fd) | |
536 | files->next_fd = fd + 1; | |
537 | ||
1dce27c5 | 538 | __set_open_fd(fd, fdt); |
1027abe8 | 539 | if (flags & O_CLOEXEC) |
1dce27c5 | 540 | __set_close_on_exec(fd, fdt); |
1027abe8 | 541 | else |
1dce27c5 | 542 | __clear_close_on_exec(fd, fdt); |
1027abe8 AV |
543 | error = fd; |
544 | #if 1 | |
545 | /* Sanity check */ | |
add1f099 | 546 | if (rcu_access_pointer(fdt->fd[fd]) != NULL) { |
1027abe8 AV |
547 | printk(KERN_WARNING "alloc_fd: slot %d not NULL!\n", fd); |
548 | rcu_assign_pointer(fdt->fd[fd], NULL); | |
549 | } | |
550 | #endif | |
551 | ||
552 | out: | |
553 | spin_unlock(&files->file_lock); | |
554 | return error; | |
555 | } | |
556 | ||
4022e7af JA |
557 | int __get_unused_fd_flags(unsigned flags, unsigned long nofile) |
558 | { | |
aa384d10 | 559 | return alloc_fd(0, nofile, flags); |
4022e7af JA |
560 | } |
561 | ||
1a7bd226 | 562 | int get_unused_fd_flags(unsigned flags) |
1027abe8 | 563 | { |
4022e7af | 564 | return __get_unused_fd_flags(flags, rlimit(RLIMIT_NOFILE)); |
1027abe8 | 565 | } |
1a7bd226 | 566 | EXPORT_SYMBOL(get_unused_fd_flags); |
56007cae AV |
567 | |
568 | static void __put_unused_fd(struct files_struct *files, unsigned int fd) | |
569 | { | |
570 | struct fdtable *fdt = files_fdtable(files); | |
571 | __clear_open_fd(fd, fdt); | |
572 | if (fd < files->next_fd) | |
573 | files->next_fd = fd; | |
574 | } | |
575 | ||
576 | void put_unused_fd(unsigned int fd) | |
577 | { | |
578 | struct files_struct *files = current->files; | |
579 | spin_lock(&files->file_lock); | |
580 | __put_unused_fd(files, fd); | |
581 | spin_unlock(&files->file_lock); | |
582 | } | |
583 | ||
584 | EXPORT_SYMBOL(put_unused_fd); | |
585 | ||
586 | /* | |
587 | * Install a file pointer in the fd array. | |
588 | * | |
589 | * The VFS is full of places where we drop the files lock between | |
590 | * setting the open_fds bitmap and installing the file in the file | |
591 | * array. At any such point, we are vulnerable to a dup2() race | |
592 | * installing a file in the array before us. We need to detect this and | |
593 | * fput() the struct file we are about to overwrite in this case. | |
594 | * | |
595 | * It should never happen - if we allow dup2() do it, _really_ bad things | |
596 | * will follow. | |
f869e8a7 | 597 | * |
d74ba04d EB |
598 | * This consumes the "file" refcount, so callers should treat it |
599 | * as if they had called fput(file). | |
56007cae AV |
600 | */ |
601 | ||
d74ba04d | 602 | void fd_install(unsigned int fd, struct file *file) |
56007cae | 603 | { |
d74ba04d | 604 | struct files_struct *files = current->files; |
56007cae | 605 | struct fdtable *fdt; |
6cf41fcf CB |
606 | |
607 | if (WARN_ON_ONCE(unlikely(file->f_mode & FMODE_BACKING))) | |
608 | return; | |
8a81252b | 609 | |
8a81252b ED |
610 | rcu_read_lock_sched(); |
611 | ||
c02b1a9b | 612 | if (unlikely(files->resize_in_progress)) { |
8a81252b | 613 | rcu_read_unlock_sched(); |
c02b1a9b MG |
614 | spin_lock(&files->file_lock); |
615 | fdt = files_fdtable(files); | |
616 | BUG_ON(fdt->fd[fd] != NULL); | |
617 | rcu_assign_pointer(fdt->fd[fd], file); | |
618 | spin_unlock(&files->file_lock); | |
619 | return; | |
8a81252b ED |
620 | } |
621 | /* coupled with smp_wmb() in expand_fdtable() */ | |
622 | smp_rmb(); | |
623 | fdt = rcu_dereference_sched(files->fdt); | |
56007cae AV |
624 | BUG_ON(fdt->fd[fd] != NULL); |
625 | rcu_assign_pointer(fdt->fd[fd], file); | |
8a81252b | 626 | rcu_read_unlock_sched(); |
56007cae AV |
627 | } |
628 | ||
629 | EXPORT_SYMBOL(fd_install); | |
0ee8cdfe | 630 | |
f49fd6d3 CB |
631 | /** |
632 | * pick_file - return file associatd with fd | |
633 | * @files: file struct to retrieve file from | |
634 | * @fd: file descriptor to retrieve file for | |
635 | * | |
6319194e | 636 | * Context: files_lock must be held. |
f49fd6d3 | 637 | * |
6319194e | 638 | * Returns: The file associated with @fd (NULL if @fd is not open) |
f49fd6d3 | 639 | */ |
278a5fba | 640 | static struct file *pick_file(struct files_struct *files, unsigned fd) |
483ce1d4 | 641 | { |
6319194e | 642 | struct fdtable *fdt = files_fdtable(files); |
f49fd6d3 | 643 | struct file *file; |
483ce1d4 | 644 | |
6319194e AV |
645 | if (fd >= fdt->max_fds) |
646 | return NULL; | |
647 | ||
609d5444 | 648 | fd = array_index_nospec(fd, fdt->max_fds); |
483ce1d4 | 649 | file = fdt->fd[fd]; |
6319194e AV |
650 | if (file) { |
651 | rcu_assign_pointer(fdt->fd[fd], NULL); | |
652 | __put_unused_fd(files, fd); | |
f49fd6d3 | 653 | } |
278a5fba CB |
654 | return file; |
655 | } | |
656 | ||
8760c909 | 657 | int close_fd(unsigned fd) |
278a5fba | 658 | { |
8760c909 | 659 | struct files_struct *files = current->files; |
278a5fba CB |
660 | struct file *file; |
661 | ||
6319194e | 662 | spin_lock(&files->file_lock); |
278a5fba | 663 | file = pick_file(files, fd); |
6319194e AV |
664 | spin_unlock(&files->file_lock); |
665 | if (!file) | |
278a5fba CB |
666 | return -EBADF; |
667 | ||
668 | return filp_close(file, files); | |
483ce1d4 | 669 | } |
8760c909 | 670 | EXPORT_SYMBOL(close_fd); /* for ksys_close() */ |
483ce1d4 | 671 | |
9b5b8722 CB |
672 | /** |
673 | * last_fd - return last valid index into fd table | |
35931eb3 | 674 | * @fdt: File descriptor table. |
9b5b8722 CB |
675 | * |
676 | * Context: Either rcu read lock or files_lock must be held. | |
677 | * | |
678 | * Returns: Last valid index into fdtable. | |
679 | */ | |
680 | static inline unsigned last_fd(struct fdtable *fdt) | |
681 | { | |
682 | return fdt->max_fds - 1; | |
683 | } | |
684 | ||
582f1fb6 GS |
685 | static inline void __range_cloexec(struct files_struct *cur_fds, |
686 | unsigned int fd, unsigned int max_fd) | |
687 | { | |
688 | struct fdtable *fdt; | |
689 | ||
9b5b8722 | 690 | /* make sure we're using the correct maximum value */ |
582f1fb6 GS |
691 | spin_lock(&cur_fds->file_lock); |
692 | fdt = files_fdtable(cur_fds); | |
9b5b8722 CB |
693 | max_fd = min(last_fd(fdt), max_fd); |
694 | if (fd <= max_fd) | |
695 | bitmap_set(fdt->close_on_exec, fd, max_fd - fd + 1); | |
582f1fb6 GS |
696 | spin_unlock(&cur_fds->file_lock); |
697 | } | |
698 | ||
ed192c59 | 699 | static inline void __range_close(struct files_struct *files, unsigned int fd, |
582f1fb6 GS |
700 | unsigned int max_fd) |
701 | { | |
ed192c59 | 702 | struct file *file; |
6319194e AV |
703 | unsigned n; |
704 | ||
ed192c59 MG |
705 | spin_lock(&files->file_lock); |
706 | n = last_fd(files_fdtable(files)); | |
6319194e AV |
707 | max_fd = min(max_fd, n); |
708 | ||
ed192c59 MG |
709 | for (; fd <= max_fd; fd++) { |
710 | file = pick_file(files, fd); | |
6319194e | 711 | if (file) { |
ed192c59 MG |
712 | spin_unlock(&files->file_lock); |
713 | filp_close(file, files); | |
714 | cond_resched(); | |
715 | spin_lock(&files->file_lock); | |
716 | } else if (need_resched()) { | |
717 | spin_unlock(&files->file_lock); | |
f49fd6d3 | 718 | cond_resched(); |
ed192c59 | 719 | spin_lock(&files->file_lock); |
f49fd6d3 | 720 | } |
582f1fb6 | 721 | } |
ed192c59 | 722 | spin_unlock(&files->file_lock); |
582f1fb6 GS |
723 | } |
724 | ||
278a5fba CB |
725 | /** |
726 | * __close_range() - Close all file descriptors in a given range. | |
727 | * | |
728 | * @fd: starting file descriptor to close | |
729 | * @max_fd: last file descriptor to close | |
35931eb3 | 730 | * @flags: CLOSE_RANGE flags. |
278a5fba CB |
731 | * |
732 | * This closes a range of file descriptors. All file descriptors | |
733 | * from @fd up to and including @max_fd are closed. | |
734 | */ | |
60997c3d | 735 | int __close_range(unsigned fd, unsigned max_fd, unsigned int flags) |
278a5fba | 736 | { |
60997c3d CB |
737 | struct task_struct *me = current; |
738 | struct files_struct *cur_fds = me->files, *fds = NULL; | |
739 | ||
582f1fb6 | 740 | if (flags & ~(CLOSE_RANGE_UNSHARE | CLOSE_RANGE_CLOEXEC)) |
60997c3d | 741 | return -EINVAL; |
278a5fba CB |
742 | |
743 | if (fd > max_fd) | |
744 | return -EINVAL; | |
745 | ||
60997c3d CB |
746 | if (flags & CLOSE_RANGE_UNSHARE) { |
747 | int ret; | |
748 | unsigned int max_unshare_fds = NR_OPEN_MAX; | |
749 | ||
750 | /* | |
03ba0fe4 CB |
751 | * If the caller requested all fds to be made cloexec we always |
752 | * copy all of the file descriptors since they still want to | |
753 | * use them. | |
60997c3d | 754 | */ |
03ba0fe4 CB |
755 | if (!(flags & CLOSE_RANGE_CLOEXEC)) { |
756 | /* | |
757 | * If the requested range is greater than the current | |
758 | * maximum, we're closing everything so only copy all | |
759 | * file descriptors beneath the lowest file descriptor. | |
760 | */ | |
761 | rcu_read_lock(); | |
762 | if (max_fd >= last_fd(files_fdtable(cur_fds))) | |
763 | max_unshare_fds = fd; | |
764 | rcu_read_unlock(); | |
765 | } | |
60997c3d CB |
766 | |
767 | ret = unshare_fd(CLONE_FILES, max_unshare_fds, &fds); | |
768 | if (ret) | |
769 | return ret; | |
770 | ||
771 | /* | |
772 | * We used to share our file descriptor table, and have now | |
773 | * created a private one, make sure we're using it below. | |
774 | */ | |
775 | if (fds) | |
776 | swap(cur_fds, fds); | |
777 | } | |
778 | ||
582f1fb6 GS |
779 | if (flags & CLOSE_RANGE_CLOEXEC) |
780 | __range_cloexec(cur_fds, fd, max_fd); | |
781 | else | |
782 | __range_close(cur_fds, fd, max_fd); | |
278a5fba | 783 | |
60997c3d CB |
784 | if (fds) { |
785 | /* | |
786 | * We're done closing the files we were supposed to. Time to install | |
787 | * the new file descriptor table and drop the old one. | |
788 | */ | |
789 | task_lock(me); | |
790 | me->files = cur_fds; | |
791 | task_unlock(me); | |
792 | put_files_struct(fds); | |
793 | } | |
794 | ||
278a5fba CB |
795 | return 0; |
796 | } | |
797 | ||
80cd7956 | 798 | /* |
53dec2ea JA |
799 | * See close_fd_get_file() below, this variant assumes current->files->file_lock |
800 | * is held. | |
80cd7956 | 801 | */ |
6319194e | 802 | struct file *__close_fd_get_file(unsigned int fd) |
80cd7956 | 803 | { |
6319194e | 804 | return pick_file(current->files, fd); |
80cd7956 TK |
805 | } |
806 | ||
53dec2ea JA |
807 | /* |
808 | * variant of close_fd that gets a ref on the file for later fput. | |
40a19260 | 809 | * The caller must ensure that filp_close() called on the file. |
53dec2ea | 810 | */ |
6319194e | 811 | struct file *close_fd_get_file(unsigned int fd) |
53dec2ea JA |
812 | { |
813 | struct files_struct *files = current->files; | |
6319194e | 814 | struct file *file; |
53dec2ea JA |
815 | |
816 | spin_lock(&files->file_lock); | |
6319194e | 817 | file = pick_file(files, fd); |
53dec2ea JA |
818 | spin_unlock(&files->file_lock); |
819 | ||
6319194e | 820 | return file; |
53dec2ea JA |
821 | } |
822 | ||
6a6d27de AV |
823 | void do_close_on_exec(struct files_struct *files) |
824 | { | |
825 | unsigned i; | |
826 | struct fdtable *fdt; | |
827 | ||
828 | /* exec unshares first */ | |
6a6d27de AV |
829 | spin_lock(&files->file_lock); |
830 | for (i = 0; ; i++) { | |
831 | unsigned long set; | |
832 | unsigned fd = i * BITS_PER_LONG; | |
833 | fdt = files_fdtable(files); | |
834 | if (fd >= fdt->max_fds) | |
835 | break; | |
836 | set = fdt->close_on_exec[i]; | |
837 | if (!set) | |
838 | continue; | |
839 | fdt->close_on_exec[i] = 0; | |
840 | for ( ; set ; fd++, set >>= 1) { | |
841 | struct file *file; | |
842 | if (!(set & 1)) | |
843 | continue; | |
844 | file = fdt->fd[fd]; | |
845 | if (!file) | |
846 | continue; | |
847 | rcu_assign_pointer(fdt->fd[fd], NULL); | |
848 | __put_unused_fd(files, fd); | |
849 | spin_unlock(&files->file_lock); | |
850 | filp_close(file, files); | |
851 | cond_resched(); | |
852 | spin_lock(&files->file_lock); | |
853 | } | |
854 | ||
855 | } | |
856 | spin_unlock(&files->file_lock); | |
857 | } | |
858 | ||
0ede61d8 CB |
859 | static struct file *__get_file_rcu(struct file __rcu **f) |
860 | { | |
861 | struct file __rcu *file; | |
862 | struct file __rcu *file_reloaded; | |
863 | struct file __rcu *file_reloaded_cmp; | |
864 | ||
865 | file = rcu_dereference_raw(*f); | |
866 | if (!file) | |
867 | return NULL; | |
868 | ||
869 | if (unlikely(!atomic_long_inc_not_zero(&file->f_count))) | |
870 | return ERR_PTR(-EAGAIN); | |
871 | ||
872 | file_reloaded = rcu_dereference_raw(*f); | |
873 | ||
874 | /* | |
875 | * Ensure that all accesses have a dependency on the load from | |
876 | * rcu_dereference_raw() above so we get correct ordering | |
877 | * between reuse/allocation and the pointer check below. | |
878 | */ | |
879 | file_reloaded_cmp = file_reloaded; | |
880 | OPTIMIZER_HIDE_VAR(file_reloaded_cmp); | |
881 | ||
882 | /* | |
883 | * atomic_long_inc_not_zero() above provided a full memory | |
884 | * barrier when we acquired a reference. | |
885 | * | |
886 | * This is paired with the write barrier from assigning to the | |
887 | * __rcu protected file pointer so that if that pointer still | |
888 | * matches the current file, we know we have successfully | |
889 | * acquired a reference to the right file. | |
890 | * | |
891 | * If the pointers don't match the file has been reallocated by | |
892 | * SLAB_TYPESAFE_BY_RCU. | |
893 | */ | |
894 | if (file == file_reloaded_cmp) | |
895 | return file_reloaded; | |
896 | ||
897 | fput(file); | |
898 | return ERR_PTR(-EAGAIN); | |
899 | } | |
900 | ||
901 | /** | |
902 | * get_file_rcu - try go get a reference to a file under rcu | |
903 | * @f: the file to get a reference on | |
904 | * | |
905 | * This function tries to get a reference on @f carefully verifying that | |
906 | * @f hasn't been reused. | |
907 | * | |
908 | * This function should rarely have to be used and only by users who | |
909 | * understand the implications of SLAB_TYPESAFE_BY_RCU. Try to avoid it. | |
910 | * | |
911 | * Return: Returns @f with the reference count increased or NULL. | |
912 | */ | |
913 | struct file *get_file_rcu(struct file __rcu **f) | |
914 | { | |
915 | for (;;) { | |
916 | struct file __rcu *file; | |
917 | ||
918 | file = __get_file_rcu(f); | |
919 | if (unlikely(!file)) | |
920 | return NULL; | |
921 | ||
922 | if (unlikely(IS_ERR(file))) | |
923 | continue; | |
924 | ||
925 | return file; | |
926 | } | |
927 | } | |
928 | EXPORT_SYMBOL_GPL(get_file_rcu); | |
929 | ||
61d4fb0b CB |
930 | /** |
931 | * get_file_active - try go get a reference to a file | |
932 | * @f: the file to get a reference on | |
933 | * | |
934 | * In contast to get_file_rcu() the pointer itself isn't part of the | |
935 | * reference counting. | |
936 | * | |
937 | * This function should rarely have to be used and only by users who | |
938 | * understand the implications of SLAB_TYPESAFE_BY_RCU. Try to avoid it. | |
939 | * | |
940 | * Return: Returns @f with the reference count increased or NULL. | |
941 | */ | |
942 | struct file *get_file_active(struct file **f) | |
943 | { | |
944 | struct file __rcu *file; | |
945 | ||
946 | rcu_read_lock(); | |
947 | file = __get_file_rcu(f); | |
948 | rcu_read_unlock(); | |
949 | if (IS_ERR(file)) | |
950 | file = NULL; | |
951 | return file; | |
952 | } | |
953 | EXPORT_SYMBOL_GPL(get_file_active); | |
954 | ||
e386dfc5 | 955 | static inline struct file *__fget_files_rcu(struct files_struct *files, |
0ede61d8 | 956 | unsigned int fd, fmode_t mask) |
0ee8cdfe | 957 | { |
e386dfc5 LT |
958 | for (;;) { |
959 | struct file *file; | |
960 | struct fdtable *fdt = rcu_dereference_raw(files->fdt); | |
961 | struct file __rcu **fdentry; | |
0ee8cdfe | 962 | |
e386dfc5 LT |
963 | if (unlikely(fd >= fdt->max_fds)) |
964 | return NULL; | |
965 | ||
966 | fdentry = fdt->fd + array_index_nospec(fd, fdt->max_fds); | |
e386dfc5 LT |
967 | |
968 | /* | |
969 | * Ok, we have a file pointer. However, because we do | |
970 | * this all locklessly under RCU, we may be racing with | |
971 | * that file being closed. | |
972 | * | |
973 | * Such a race can take two forms: | |
974 | * | |
0ede61d8 CB |
975 | * (a) the file ref already went down to zero and the |
976 | * file hasn't been reused yet or the file count | |
977 | * isn't zero but the file has already been reused. | |
e386dfc5 | 978 | */ |
0ede61d8 CB |
979 | file = __get_file_rcu(fdentry); |
980 | if (unlikely(!file)) | |
981 | return NULL; | |
982 | ||
983 | if (unlikely(IS_ERR(file))) | |
e386dfc5 LT |
984 | continue; |
985 | ||
986 | /* | |
987 | * (b) the file table entry has changed under us. | |
988 | * Note that we don't need to re-check the 'fdt->fd' | |
989 | * pointer having changed, because it always goes | |
990 | * hand-in-hand with 'fdt'. | |
991 | * | |
81132a39 | 992 | * If so, we need to put our ref and try again. |
5ba97d28 | 993 | */ |
0ede61d8 | 994 | if (unlikely(rcu_dereference_raw(files->fdt) != fdt)) { |
81132a39 | 995 | fput(file); |
e386dfc5 | 996 | continue; |
054aa8d4 | 997 | } |
e386dfc5 | 998 | |
0ede61d8 CB |
999 | /* |
1000 | * This isn't the file we're looking for or we're not | |
1001 | * allowed to get a reference to it. | |
1002 | */ | |
1003 | if (unlikely(file->f_mode & mask)) { | |
1004 | fput(file); | |
1005 | return NULL; | |
1006 | } | |
1007 | ||
e386dfc5 LT |
1008 | /* |
1009 | * Ok, we have a ref to the file, and checked that it | |
1010 | * still exists. | |
1011 | */ | |
1012 | return file; | |
0ee8cdfe | 1013 | } |
e386dfc5 LT |
1014 | } |
1015 | ||
1016 | static struct file *__fget_files(struct files_struct *files, unsigned int fd, | |
81132a39 | 1017 | fmode_t mask) |
e386dfc5 LT |
1018 | { |
1019 | struct file *file; | |
1020 | ||
1021 | rcu_read_lock(); | |
81132a39 | 1022 | file = __fget_files_rcu(files, fd, mask); |
0ee8cdfe AV |
1023 | rcu_read_unlock(); |
1024 | ||
1025 | return file; | |
1026 | } | |
1027 | ||
81132a39 | 1028 | static inline struct file *__fget(unsigned int fd, fmode_t mask) |
5e876fb4 | 1029 | { |
81132a39 | 1030 | return __fget_files(current->files, fd, mask); |
091141a4 JA |
1031 | } |
1032 | ||
1deb46e2 ON |
1033 | struct file *fget(unsigned int fd) |
1034 | { | |
81132a39 | 1035 | return __fget(fd, FMODE_PATH); |
1deb46e2 | 1036 | } |
0ee8cdfe AV |
1037 | EXPORT_SYMBOL(fget); |
1038 | ||
1039 | struct file *fget_raw(unsigned int fd) | |
1040 | { | |
81132a39 | 1041 | return __fget(fd, 0); |
0ee8cdfe | 1042 | } |
0ee8cdfe AV |
1043 | EXPORT_SYMBOL(fget_raw); |
1044 | ||
5e876fb4 SD |
1045 | struct file *fget_task(struct task_struct *task, unsigned int fd) |
1046 | { | |
1047 | struct file *file = NULL; | |
1048 | ||
1049 | task_lock(task); | |
1050 | if (task->files) | |
81132a39 | 1051 | file = __fget_files(task->files, fd, 0); |
5e876fb4 SD |
1052 | task_unlock(task); |
1053 | ||
1054 | return file; | |
1055 | } | |
1056 | ||
0ede61d8 CB |
1057 | struct file *lookup_fdget_rcu(unsigned int fd) |
1058 | { | |
1059 | return __fget_files_rcu(current->files, fd, 0); | |
1060 | ||
1061 | } | |
1062 | EXPORT_SYMBOL_GPL(lookup_fdget_rcu); | |
1063 | ||
1064 | struct file *task_lookup_fdget_rcu(struct task_struct *task, unsigned int fd) | |
3a879fb3 EB |
1065 | { |
1066 | /* Must be called with rcu_read_lock held */ | |
1067 | struct files_struct *files; | |
1068 | struct file *file = NULL; | |
1069 | ||
1070 | task_lock(task); | |
1071 | files = task->files; | |
1072 | if (files) | |
0ede61d8 | 1073 | file = __fget_files_rcu(files, fd, 0); |
3a879fb3 EB |
1074 | task_unlock(task); |
1075 | ||
1076 | return file; | |
1077 | } | |
1078 | ||
0ede61d8 | 1079 | struct file *task_lookup_next_fdget_rcu(struct task_struct *task, unsigned int *ret_fd) |
e9a53aeb EB |
1080 | { |
1081 | /* Must be called with rcu_read_lock held */ | |
1082 | struct files_struct *files; | |
1083 | unsigned int fd = *ret_fd; | |
1084 | struct file *file = NULL; | |
1085 | ||
1086 | task_lock(task); | |
1087 | files = task->files; | |
1088 | if (files) { | |
1089 | for (; fd < files_fdtable(files)->max_fds; fd++) { | |
0ede61d8 | 1090 | file = __fget_files_rcu(files, fd, 0); |
e9a53aeb EB |
1091 | if (file) |
1092 | break; | |
1093 | } | |
1094 | } | |
1095 | task_unlock(task); | |
1096 | *ret_fd = fd; | |
1097 | return file; | |
1098 | } | |
0ede61d8 | 1099 | EXPORT_SYMBOL(task_lookup_next_fdget_rcu); |
e9a53aeb | 1100 | |
0ee8cdfe AV |
1101 | /* |
1102 | * Lightweight file lookup - no refcnt increment if fd table isn't shared. | |
1103 | * | |
1104 | * You can use this instead of fget if you satisfy all of the following | |
1105 | * conditions: | |
1106 | * 1) You must call fput_light before exiting the syscall and returning control | |
1107 | * to userspace (i.e. you cannot remember the returned struct file * after | |
1108 | * returning to userspace). | |
1109 | * 2) You must not call filp_close on the returned struct file * in between | |
1110 | * calls to fget_light and fput_light. | |
1111 | * 3) You must not clone the current task in between the calls to fget_light | |
1112 | * and fput_light. | |
1113 | * | |
1114 | * The fput_needed flag returned by fget_light should be passed to the | |
1115 | * corresponding fput_light. | |
1116 | */ | |
bd2a31d5 | 1117 | static unsigned long __fget_light(unsigned int fd, fmode_t mask) |
0ee8cdfe | 1118 | { |
0ee8cdfe | 1119 | struct files_struct *files = current->files; |
ad461834 | 1120 | struct file *file; |
0ee8cdfe | 1121 | |
7ee47dcf JH |
1122 | /* |
1123 | * If another thread is concurrently calling close_fd() followed | |
1124 | * by put_files_struct(), we must not observe the old table | |
1125 | * entry combined with the new refcount - otherwise we could | |
1126 | * return a file that is concurrently being freed. | |
1127 | * | |
1128 | * atomic_read_acquire() pairs with atomic_dec_and_test() in | |
1129 | * put_files_struct(). | |
1130 | */ | |
1131 | if (atomic_read_acquire(&files->count) == 1) { | |
bebf684b | 1132 | file = files_lookup_fd_raw(files, fd); |
bd2a31d5 AV |
1133 | if (!file || unlikely(file->f_mode & mask)) |
1134 | return 0; | |
1135 | return (unsigned long)file; | |
0ee8cdfe | 1136 | } else { |
81132a39 | 1137 | file = __fget(fd, mask); |
bd2a31d5 AV |
1138 | if (!file) |
1139 | return 0; | |
1140 | return FDPUT_FPUT | (unsigned long)file; | |
0ee8cdfe | 1141 | } |
0ee8cdfe | 1142 | } |
bd2a31d5 | 1143 | unsigned long __fdget(unsigned int fd) |
ad461834 | 1144 | { |
bd2a31d5 | 1145 | return __fget_light(fd, FMODE_PATH); |
ad461834 | 1146 | } |
bd2a31d5 | 1147 | EXPORT_SYMBOL(__fdget); |
0ee8cdfe | 1148 | |
bd2a31d5 | 1149 | unsigned long __fdget_raw(unsigned int fd) |
0ee8cdfe | 1150 | { |
bd2a31d5 | 1151 | return __fget_light(fd, 0); |
0ee8cdfe | 1152 | } |
fe17f22d | 1153 | |
79796425 LT |
1154 | /* |
1155 | * Try to avoid f_pos locking. We only need it if the | |
1156 | * file is marked for FMODE_ATOMIC_POS, and it can be | |
1157 | * accessed multiple ways. | |
1158 | * | |
1159 | * Always do it for directories, because pidfd_getfd() | |
1160 | * can make a file accessible even if it otherwise would | |
1161 | * not be, and for directories this is a correctness | |
1162 | * issue, not a "POSIX requirement". | |
1163 | */ | |
1164 | static inline bool file_needs_f_pos_lock(struct file *file) | |
1165 | { | |
1166 | return (file->f_mode & FMODE_ATOMIC_POS) && | |
7d84d1b9 | 1167 | (file_count(file) > 1 || file->f_op->iterate_shared); |
79796425 LT |
1168 | } |
1169 | ||
bd2a31d5 AV |
1170 | unsigned long __fdget_pos(unsigned int fd) |
1171 | { | |
99aea681 EB |
1172 | unsigned long v = __fdget(fd); |
1173 | struct file *file = (struct file *)(v & ~3); | |
bd2a31d5 | 1174 | |
79796425 | 1175 | if (file && file_needs_f_pos_lock(file)) { |
20ea1e7d CB |
1176 | v |= FDPUT_POS_UNLOCK; |
1177 | mutex_lock(&file->f_pos_lock); | |
bd2a31d5 | 1178 | } |
99aea681 | 1179 | return v; |
bd2a31d5 AV |
1180 | } |
1181 | ||
63b6df14 AV |
1182 | void __f_unlock_pos(struct file *f) |
1183 | { | |
1184 | mutex_unlock(&f->f_pos_lock); | |
1185 | } | |
1186 | ||
bd2a31d5 AV |
1187 | /* |
1188 | * We only lock f_pos if we have threads or if the file might be | |
1189 | * shared with another process. In both cases we'll have an elevated | |
1190 | * file count (done either by fdget() or by fork()). | |
1191 | */ | |
1192 | ||
fe17f22d AV |
1193 | void set_close_on_exec(unsigned int fd, int flag) |
1194 | { | |
1195 | struct files_struct *files = current->files; | |
1196 | struct fdtable *fdt; | |
1197 | spin_lock(&files->file_lock); | |
1198 | fdt = files_fdtable(files); | |
1199 | if (flag) | |
1200 | __set_close_on_exec(fd, fdt); | |
1201 | else | |
1202 | __clear_close_on_exec(fd, fdt); | |
1203 | spin_unlock(&files->file_lock); | |
1204 | } | |
1205 | ||
1206 | bool get_close_on_exec(unsigned int fd) | |
1207 | { | |
1208 | struct files_struct *files = current->files; | |
1209 | struct fdtable *fdt; | |
1210 | bool res; | |
1211 | rcu_read_lock(); | |
1212 | fdt = files_fdtable(files); | |
1213 | res = close_on_exec(fd, fdt); | |
1214 | rcu_read_unlock(); | |
1215 | return res; | |
1216 | } | |
1217 | ||
8280d161 AV |
1218 | static int do_dup2(struct files_struct *files, |
1219 | struct file *file, unsigned fd, unsigned flags) | |
e983094d | 1220 | __releases(&files->file_lock) |
fe17f22d | 1221 | { |
8280d161 | 1222 | struct file *tofree; |
fe17f22d AV |
1223 | struct fdtable *fdt; |
1224 | ||
fe17f22d AV |
1225 | /* |
1226 | * We need to detect attempts to do dup2() over allocated but still | |
1227 | * not finished descriptor. NB: OpenBSD avoids that at the price of | |
1228 | * extra work in their equivalent of fget() - they insert struct | |
1229 | * file immediately after grabbing descriptor, mark it larval if | |
1230 | * more work (e.g. actual opening) is needed and make sure that | |
1231 | * fget() treats larval files as absent. Potentially interesting, | |
1232 | * but while extra work in fget() is trivial, locking implications | |
1233 | * and amount of surgery on open()-related paths in VFS are not. | |
1234 | * FreeBSD fails with -EBADF in the same situation, NetBSD "solution" | |
1235 | * deadlocks in rather amusing ways, AFAICS. All of that is out of | |
1236 | * scope of POSIX or SUS, since neither considers shared descriptor | |
1237 | * tables and this condition does not arise without those. | |
1238 | */ | |
fe17f22d | 1239 | fdt = files_fdtable(files); |
8280d161 AV |
1240 | tofree = fdt->fd[fd]; |
1241 | if (!tofree && fd_is_open(fd, fdt)) | |
1242 | goto Ebusy; | |
fe17f22d | 1243 | get_file(file); |
8280d161 AV |
1244 | rcu_assign_pointer(fdt->fd[fd], file); |
1245 | __set_open_fd(fd, fdt); | |
fe17f22d | 1246 | if (flags & O_CLOEXEC) |
8280d161 | 1247 | __set_close_on_exec(fd, fdt); |
fe17f22d | 1248 | else |
8280d161 | 1249 | __clear_close_on_exec(fd, fdt); |
fe17f22d AV |
1250 | spin_unlock(&files->file_lock); |
1251 | ||
1252 | if (tofree) | |
1253 | filp_close(tofree, files); | |
1254 | ||
8280d161 AV |
1255 | return fd; |
1256 | ||
1257 | Ebusy: | |
1258 | spin_unlock(&files->file_lock); | |
1259 | return -EBUSY; | |
1260 | } | |
1261 | ||
1262 | int replace_fd(unsigned fd, struct file *file, unsigned flags) | |
1263 | { | |
1264 | int err; | |
1265 | struct files_struct *files = current->files; | |
1266 | ||
1267 | if (!file) | |
8760c909 | 1268 | return close_fd(fd); |
8280d161 AV |
1269 | |
1270 | if (fd >= rlimit(RLIMIT_NOFILE)) | |
08f05c49 | 1271 | return -EBADF; |
8280d161 AV |
1272 | |
1273 | spin_lock(&files->file_lock); | |
1274 | err = expand_files(files, fd); | |
1275 | if (unlikely(err < 0)) | |
1276 | goto out_unlock; | |
1277 | return do_dup2(files, file, fd, flags); | |
1278 | ||
1279 | out_unlock: | |
1280 | spin_unlock(&files->file_lock); | |
1281 | return err; | |
1282 | } | |
1283 | ||
66590610 KC |
1284 | /** |
1285 | * __receive_fd() - Install received file into file descriptor table | |
66590610 KC |
1286 | * @file: struct file that was received from another process |
1287 | * @ufd: __user pointer to write new fd number to | |
1288 | * @o_flags: the O_* flags to apply to the new fd entry | |
1289 | * | |
1290 | * Installs a received file into the file descriptor table, with appropriate | |
deefa7f3 KC |
1291 | * checks and count updates. Optionally writes the fd number to userspace, if |
1292 | * @ufd is non-NULL. | |
66590610 KC |
1293 | * |
1294 | * This helper handles its own reference counting of the incoming | |
1295 | * struct file. | |
1296 | * | |
deefa7f3 | 1297 | * Returns newly install fd or -ve on error. |
66590610 | 1298 | */ |
42eb0d54 | 1299 | int __receive_fd(struct file *file, int __user *ufd, unsigned int o_flags) |
66590610 KC |
1300 | { |
1301 | int new_fd; | |
1302 | int error; | |
1303 | ||
1304 | error = security_file_receive(file); | |
1305 | if (error) | |
1306 | return error; | |
1307 | ||
42eb0d54 CH |
1308 | new_fd = get_unused_fd_flags(o_flags); |
1309 | if (new_fd < 0) | |
1310 | return new_fd; | |
66590610 | 1311 | |
deefa7f3 KC |
1312 | if (ufd) { |
1313 | error = put_user(new_fd, ufd); | |
1314 | if (error) { | |
42eb0d54 | 1315 | put_unused_fd(new_fd); |
deefa7f3 KC |
1316 | return error; |
1317 | } | |
66590610 KC |
1318 | } |
1319 | ||
42eb0d54 CH |
1320 | fd_install(new_fd, get_file(file)); |
1321 | __receive_sock(file); | |
1322 | return new_fd; | |
1323 | } | |
17381715 | 1324 | |
42eb0d54 CH |
1325 | int receive_fd_replace(int new_fd, struct file *file, unsigned int o_flags) |
1326 | { | |
1327 | int error; | |
1328 | ||
1329 | error = security_file_receive(file); | |
1330 | if (error) | |
1331 | return error; | |
1332 | error = replace_fd(new_fd, file, o_flags); | |
1333 | if (error) | |
1334 | return error; | |
66590610 | 1335 | __receive_sock(file); |
deefa7f3 | 1336 | return new_fd; |
66590610 KC |
1337 | } |
1338 | ||
9c930054 XY |
1339 | int receive_fd(struct file *file, unsigned int o_flags) |
1340 | { | |
1341 | return __receive_fd(file, NULL, o_flags); | |
1342 | } | |
1343 | EXPORT_SYMBOL_GPL(receive_fd); | |
1344 | ||
c7248321 | 1345 | static int ksys_dup3(unsigned int oldfd, unsigned int newfd, int flags) |
8280d161 AV |
1346 | { |
1347 | int err = -EBADF; | |
1348 | struct file *file; | |
1349 | struct files_struct *files = current->files; | |
1350 | ||
1351 | if ((flags & ~O_CLOEXEC) != 0) | |
1352 | return -EINVAL; | |
1353 | ||
aed97647 RJ |
1354 | if (unlikely(oldfd == newfd)) |
1355 | return -EINVAL; | |
1356 | ||
8280d161 | 1357 | if (newfd >= rlimit(RLIMIT_NOFILE)) |
08f05c49 | 1358 | return -EBADF; |
8280d161 AV |
1359 | |
1360 | spin_lock(&files->file_lock); | |
1361 | err = expand_files(files, newfd); | |
120ce2b0 | 1362 | file = files_lookup_fd_locked(files, oldfd); |
8280d161 AV |
1363 | if (unlikely(!file)) |
1364 | goto Ebadf; | |
1365 | if (unlikely(err < 0)) { | |
1366 | if (err == -EMFILE) | |
1367 | goto Ebadf; | |
1368 | goto out_unlock; | |
1369 | } | |
1370 | return do_dup2(files, file, newfd, flags); | |
fe17f22d AV |
1371 | |
1372 | Ebadf: | |
1373 | err = -EBADF; | |
1374 | out_unlock: | |
1375 | spin_unlock(&files->file_lock); | |
1376 | return err; | |
1377 | } | |
1378 | ||
c7248321 DB |
1379 | SYSCALL_DEFINE3(dup3, unsigned int, oldfd, unsigned int, newfd, int, flags) |
1380 | { | |
1381 | return ksys_dup3(oldfd, newfd, flags); | |
1382 | } | |
1383 | ||
fe17f22d AV |
1384 | SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd) |
1385 | { | |
1386 | if (unlikely(newfd == oldfd)) { /* corner case */ | |
1387 | struct files_struct *files = current->files; | |
0ede61d8 | 1388 | struct file *f; |
fe17f22d AV |
1389 | int retval = oldfd; |
1390 | ||
1391 | rcu_read_lock(); | |
0ede61d8 CB |
1392 | f = __fget_files_rcu(files, oldfd, 0); |
1393 | if (!f) | |
fe17f22d AV |
1394 | retval = -EBADF; |
1395 | rcu_read_unlock(); | |
0ede61d8 CB |
1396 | if (f) |
1397 | fput(f); | |
fe17f22d AV |
1398 | return retval; |
1399 | } | |
c7248321 | 1400 | return ksys_dup3(oldfd, newfd, 0); |
fe17f22d AV |
1401 | } |
1402 | ||
bc1cd99a | 1403 | SYSCALL_DEFINE1(dup, unsigned int, fildes) |
fe17f22d AV |
1404 | { |
1405 | int ret = -EBADF; | |
1406 | struct file *file = fget_raw(fildes); | |
1407 | ||
1408 | if (file) { | |
8d10a035 | 1409 | ret = get_unused_fd_flags(0); |
fe17f22d AV |
1410 | if (ret >= 0) |
1411 | fd_install(ret, file); | |
1412 | else | |
1413 | fput(file); | |
1414 | } | |
1415 | return ret; | |
1416 | } | |
1417 | ||
1418 | int f_dupfd(unsigned int from, struct file *file, unsigned flags) | |
1419 | { | |
e06b53c2 | 1420 | unsigned long nofile = rlimit(RLIMIT_NOFILE); |
fe17f22d | 1421 | int err; |
e06b53c2 | 1422 | if (from >= nofile) |
fe17f22d | 1423 | return -EINVAL; |
e06b53c2 | 1424 | err = alloc_fd(from, nofile, flags); |
fe17f22d AV |
1425 | if (err >= 0) { |
1426 | get_file(file); | |
1427 | fd_install(err, file); | |
1428 | } | |
1429 | return err; | |
1430 | } | |
c3c073f8 AV |
1431 | |
1432 | int iterate_fd(struct files_struct *files, unsigned n, | |
1433 | int (*f)(const void *, struct file *, unsigned), | |
1434 | const void *p) | |
1435 | { | |
1436 | struct fdtable *fdt; | |
c3c073f8 AV |
1437 | int res = 0; |
1438 | if (!files) | |
1439 | return 0; | |
1440 | spin_lock(&files->file_lock); | |
a77cfcb4 AV |
1441 | for (fdt = files_fdtable(files); n < fdt->max_fds; n++) { |
1442 | struct file *file; | |
1443 | file = rcu_dereference_check_fdtable(files, fdt->fd[n]); | |
1444 | if (!file) | |
1445 | continue; | |
1446 | res = f(p, file, n); | |
1447 | if (res) | |
1448 | break; | |
c3c073f8 AV |
1449 | } |
1450 | spin_unlock(&files->file_lock); | |
1451 | return res; | |
1452 | } | |
1453 | EXPORT_SYMBOL(iterate_fd); |