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b2441318 1// SPDX-License-Identifier: GPL-2.0
1da177e4
LT
2/*
3 * linux/fs/readdir.c
4 *
5 * Copyright (C) 1995 Linus Torvalds
6 */
7
85c9fe8f 8#include <linux/stddef.h>
022a1692 9#include <linux/kernel.h>
630d9c47 10#include <linux/export.h>
1da177e4
LT
11#include <linux/time.h>
12#include <linux/mm.h>
13#include <linux/errno.h>
14#include <linux/stat.h>
15#include <linux/file.h>
1da177e4 16#include <linux/fs.h>
d4c7cf6c 17#include <linux/fsnotify.h>
1da177e4
LT
18#include <linux/dirent.h>
19#include <linux/security.h>
20#include <linux/syscalls.h>
21#include <linux/unistd.h>
0460b2a2 22#include <linux/compat.h>
7c0f6ba6 23#include <linux/uaccess.h>
1da177e4 24
9f79b78e
LT
25#include <asm/unaligned.h>
26
27/*
28 * Note the "unsafe_put_user() semantics: we goto a
29 * label for errors.
9f79b78e
LT
30 */
31#define unsafe_copy_dirent_name(_dst, _src, _len, label) do { \
32 char __user *dst = (_dst); \
33 const char *src = (_src); \
34 size_t len = (_len); \
c512c691
LT
35 unsafe_put_user(0, dst+len, label); \
36 unsafe_copy_to_user(dst, src, len, label); \
9f79b78e
LT
37} while (0)
38
39
5c0ba4e0 40int iterate_dir(struct file *file, struct dir_context *ctx)
1da177e4 41{
496ad9aa 42 struct inode *inode = file_inode(file);
61922694 43 bool shared = false;
1da177e4 44 int res = -ENOTDIR;
61922694
AV
45 if (file->f_op->iterate_shared)
46 shared = true;
47 else if (!file->f_op->iterate)
1da177e4
LT
48 goto out;
49
50 res = security_file_permission(file, MAY_READ);
51 if (res)
52 goto out;
53
0dc208b5
KT
54 if (shared)
55 res = down_read_killable(&inode->i_rwsem);
56 else
00235411 57 res = down_write_killable(&inode->i_rwsem);
0dc208b5
KT
58 if (res)
59 goto out;
da784511 60
1da177e4
LT
61 res = -ENOENT;
62 if (!IS_DEADDIR(inode)) {
2233f31a 63 ctx->pos = file->f_pos;
61922694
AV
64 if (shared)
65 res = file->f_op->iterate_shared(file, ctx);
66 else
67 res = file->f_op->iterate(file, ctx);
2233f31a 68 file->f_pos = ctx->pos;
d4c7cf6c 69 fsnotify_access(file);
1da177e4
LT
70 file_accessed(file);
71 }
61922694
AV
72 if (shared)
73 inode_unlock_shared(inode);
74 else
75 inode_unlock(inode);
1da177e4
LT
76out:
77 return res;
78}
5c0ba4e0 79EXPORT_SYMBOL(iterate_dir);
1da177e4 80
8a23eb80
LT
81/*
82 * POSIX says that a dirent name cannot contain NULL or a '/'.
83 *
84 * It's not 100% clear what we should really do in this case.
85 * The filesystem is clearly corrupted, but returning a hard
86 * error means that you now don't see any of the other names
87 * either, so that isn't a perfect alternative.
88 *
89 * And if you return an error, what error do you use? Several
90 * filesystems seem to have decided on EUCLEAN being the error
91 * code for EFSCORRUPTED, and that may be the error to use. Or
92 * just EIO, which is perhaps more obvious to users.
93 *
94 * In order to see the other file names in the directory, the
95 * caller might want to make this a "soft" error: skip the
96 * entry, and return the error at the end instead.
97 *
98 * Note that this should likely do a "memchr(name, 0, len)"
99 * check too, since that would be filesystem corruption as
100 * well. However, that case can't actually confuse user space,
101 * which has to do a strlen() on the name anyway to find the
102 * filename length, and the above "soft error" worry means
103 * that it's probably better left alone until we have that
104 * issue clarified.
2c6b7bcd
LT
105 *
106 * Note the PATH_MAX check - it's arbitrary but the real
107 * kernel limit on a possible path component, not NAME_MAX,
108 * which is the technical standard limit.
8a23eb80
LT
109 */
110static int verify_dirent_name(const char *name, int len)
111{
2c6b7bcd 112 if (len <= 0 || len >= PATH_MAX)
8a23eb80 113 return -EIO;
b9959c7a 114 if (memchr(name, '/', len))
8a23eb80
LT
115 return -EIO;
116 return 0;
117}
118
1da177e4
LT
119/*
120 * Traditional linux readdir() handling..
121 *
122 * "count=1" is a special case, meaning that the buffer is one
123 * dirent-structure in size and that the code can't handle more
124 * anyway. Thus the special "fillonedir()" function for that
125 * case (the low-level handlers don't need to care about this).
126 */
1da177e4
LT
127
128#ifdef __ARCH_WANT_OLD_READDIR
129
130struct old_linux_dirent {
131 unsigned long d_ino;
132 unsigned long d_offset;
133 unsigned short d_namlen;
134 char d_name[1];
135};
136
137struct readdir_callback {
5c0ba4e0 138 struct dir_context ctx;
1da177e4
LT
139 struct old_linux_dirent __user * dirent;
140 int result;
141};
142
ac7576f4
MS
143static int fillonedir(struct dir_context *ctx, const char *name, int namlen,
144 loff_t offset, u64 ino, unsigned int d_type)
1da177e4 145{
ac7576f4
MS
146 struct readdir_callback *buf =
147 container_of(ctx, struct readdir_callback, ctx);
1da177e4 148 struct old_linux_dirent __user * dirent;
afefdbb2 149 unsigned long d_ino;
1da177e4
LT
150
151 if (buf->result)
152 return -EINVAL;
0c93ac69
LT
153 buf->result = verify_dirent_name(name, namlen);
154 if (buf->result < 0)
155 return buf->result;
afefdbb2 156 d_ino = ino;
8f3f655d
AV
157 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
158 buf->result = -EOVERFLOW;
afefdbb2 159 return -EOVERFLOW;
8f3f655d 160 }
1da177e4
LT
161 buf->result++;
162 dirent = buf->dirent;
391b7461 163 if (!user_write_access_begin(dirent,
1da177e4
LT
164 (unsigned long)(dirent->d_name + namlen + 1) -
165 (unsigned long)dirent))
166 goto efault;
391b7461
AV
167 unsafe_put_user(d_ino, &dirent->d_ino, efault_end);
168 unsafe_put_user(offset, &dirent->d_offset, efault_end);
169 unsafe_put_user(namlen, &dirent->d_namlen, efault_end);
170 unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
171 user_write_access_end();
1da177e4 172 return 0;
391b7461
AV
173efault_end:
174 user_write_access_end();
1da177e4
LT
175efault:
176 buf->result = -EFAULT;
177 return -EFAULT;
178}
179
d4e82042
HC
180SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
181 struct old_linux_dirent __user *, dirent, unsigned int, count)
1da177e4
LT
182{
183 int error;
63b6df14 184 struct fd f = fdget_pos(fd);
ac6614b7
AV
185 struct readdir_callback buf = {
186 .ctx.actor = fillonedir,
187 .dirent = dirent
188 };
1da177e4 189
2903ff01 190 if (!f.file)
863ced7f 191 return -EBADF;
1da177e4 192
5c0ba4e0 193 error = iterate_dir(f.file, &buf.ctx);
53c9c5c0 194 if (buf.result)
1da177e4
LT
195 error = buf.result;
196
63b6df14 197 fdput_pos(f);
1da177e4
LT
198 return error;
199}
200
201#endif /* __ARCH_WANT_OLD_READDIR */
202
203/*
204 * New, all-improved, singing, dancing, iBCS2-compliant getdents()
205 * interface.
206 */
207struct linux_dirent {
208 unsigned long d_ino;
209 unsigned long d_off;
210 unsigned short d_reclen;
211 char d_name[1];
212};
213
214struct getdents_callback {
5c0ba4e0 215 struct dir_context ctx;
1da177e4 216 struct linux_dirent __user * current_dir;
3c2659bd 217 int prev_reclen;
1da177e4
LT
218 int count;
219 int error;
220};
221
ac7576f4
MS
222static int filldir(struct dir_context *ctx, const char *name, int namlen,
223 loff_t offset, u64 ino, unsigned int d_type)
1da177e4 224{
3c2659bd 225 struct linux_dirent __user *dirent, *prev;
ac7576f4
MS
226 struct getdents_callback *buf =
227 container_of(ctx, struct getdents_callback, ctx);
afefdbb2 228 unsigned long d_ino;
85c9fe8f
KW
229 int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
230 sizeof(long));
3c2659bd 231 int prev_reclen;
1da177e4 232
8a23eb80
LT
233 buf->error = verify_dirent_name(name, namlen);
234 if (unlikely(buf->error))
235 return buf->error;
1da177e4
LT
236 buf->error = -EINVAL; /* only used if we fail.. */
237 if (reclen > buf->count)
238 return -EINVAL;
afefdbb2 239 d_ino = ino;
8f3f655d
AV
240 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
241 buf->error = -EOVERFLOW;
afefdbb2 242 return -EOVERFLOW;
8f3f655d 243 }
3c2659bd
LT
244 prev_reclen = buf->prev_reclen;
245 if (prev_reclen && signal_pending(current))
9f79b78e 246 return -EINTR;
9f79b78e 247 dirent = buf->current_dir;
3c2659bd 248 prev = (void __user *) dirent - prev_reclen;
41cd7805 249 if (!user_write_access_begin(prev, reclen + prev_reclen))
3c2659bd
LT
250 goto efault;
251
252 /* This might be 'dirent->d_off', but if so it will get overwritten */
253 unsafe_put_user(offset, &prev->d_off, efault_end);
9f79b78e
LT
254 unsafe_put_user(d_ino, &dirent->d_ino, efault_end);
255 unsafe_put_user(reclen, &dirent->d_reclen, efault_end);
256 unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end);
257 unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
41cd7805 258 user_write_access_end();
9f79b78e 259
3c2659bd
LT
260 buf->current_dir = (void __user *)dirent + reclen;
261 buf->prev_reclen = reclen;
1da177e4
LT
262 buf->count -= reclen;
263 return 0;
9f79b78e 264efault_end:
41cd7805 265 user_write_access_end();
1da177e4
LT
266efault:
267 buf->error = -EFAULT;
268 return -EFAULT;
269}
270
20f37034
HC
271SYSCALL_DEFINE3(getdents, unsigned int, fd,
272 struct linux_dirent __user *, dirent, unsigned int, count)
1da177e4 273{
2903ff01 274 struct fd f;
ac6614b7
AV
275 struct getdents_callback buf = {
276 .ctx.actor = filldir,
277 .count = count,
278 .current_dir = dirent
279 };
1da177e4
LT
280 int error;
281
63b6df14 282 f = fdget_pos(fd);
2903ff01 283 if (!f.file)
863ced7f 284 return -EBADF;
1da177e4 285
5c0ba4e0 286 error = iterate_dir(f.file, &buf.ctx);
53c9c5c0
AV
287 if (error >= 0)
288 error = buf.error;
3c2659bd
LT
289 if (buf.prev_reclen) {
290 struct linux_dirent __user * lastdirent;
291 lastdirent = (void __user *)buf.current_dir - buf.prev_reclen;
292
bb6f619b 293 if (put_user(buf.ctx.pos, &lastdirent->d_off))
1da177e4
LT
294 error = -EFAULT;
295 else
296 error = count - buf.count;
297 }
63b6df14 298 fdput_pos(f);
1da177e4
LT
299 return error;
300}
301
1da177e4 302struct getdents_callback64 {
5c0ba4e0 303 struct dir_context ctx;
1da177e4 304 struct linux_dirent64 __user * current_dir;
3c2659bd 305 int prev_reclen;
1da177e4
LT
306 int count;
307 int error;
308};
309
ac7576f4
MS
310static int filldir64(struct dir_context *ctx, const char *name, int namlen,
311 loff_t offset, u64 ino, unsigned int d_type)
1da177e4 312{
3c2659bd 313 struct linux_dirent64 __user *dirent, *prev;
ac7576f4
MS
314 struct getdents_callback64 *buf =
315 container_of(ctx, struct getdents_callback64, ctx);
85c9fe8f
KW
316 int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
317 sizeof(u64));
3c2659bd 318 int prev_reclen;
1da177e4 319
8a23eb80
LT
320 buf->error = verify_dirent_name(name, namlen);
321 if (unlikely(buf->error))
322 return buf->error;
1da177e4
LT
323 buf->error = -EINVAL; /* only used if we fail.. */
324 if (reclen > buf->count)
325 return -EINVAL;
3c2659bd
LT
326 prev_reclen = buf->prev_reclen;
327 if (prev_reclen && signal_pending(current))
9f79b78e 328 return -EINTR;
9f79b78e 329 dirent = buf->current_dir;
3c2659bd 330 prev = (void __user *)dirent - prev_reclen;
41cd7805 331 if (!user_write_access_begin(prev, reclen + prev_reclen))
3c2659bd
LT
332 goto efault;
333
334 /* This might be 'dirent->d_off', but if so it will get overwritten */
335 unsafe_put_user(offset, &prev->d_off, efault_end);
9f79b78e
LT
336 unsafe_put_user(ino, &dirent->d_ino, efault_end);
337 unsafe_put_user(reclen, &dirent->d_reclen, efault_end);
338 unsafe_put_user(d_type, &dirent->d_type, efault_end);
339 unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
41cd7805 340 user_write_access_end();
9f79b78e 341
3c2659bd
LT
342 buf->prev_reclen = reclen;
343 buf->current_dir = (void __user *)dirent + reclen;
1da177e4
LT
344 buf->count -= reclen;
345 return 0;
3c2659bd 346
9f79b78e 347efault_end:
41cd7805 348 user_write_access_end();
1da177e4
LT
349efault:
350 buf->error = -EFAULT;
351 return -EFAULT;
352}
353
fb2da16c
CH
354SYSCALL_DEFINE3(getdents64, unsigned int, fd,
355 struct linux_dirent64 __user *, dirent, unsigned int, count)
1da177e4 356{
2903ff01 357 struct fd f;
ac6614b7
AV
358 struct getdents_callback64 buf = {
359 .ctx.actor = filldir64,
360 .count = count,
361 .current_dir = dirent
362 };
1da177e4
LT
363 int error;
364
63b6df14 365 f = fdget_pos(fd);
2903ff01 366 if (!f.file)
863ced7f 367 return -EBADF;
1da177e4 368
5c0ba4e0 369 error = iterate_dir(f.file, &buf.ctx);
53c9c5c0
AV
370 if (error >= 0)
371 error = buf.error;
3c2659bd
LT
372 if (buf.prev_reclen) {
373 struct linux_dirent64 __user * lastdirent;
bb6f619b 374 typeof(lastdirent->d_off) d_off = buf.ctx.pos;
3c2659bd
LT
375
376 lastdirent = (void __user *) buf.current_dir - buf.prev_reclen;
5fb15141 377 if (put_user(d_off, &lastdirent->d_off))
53c9c5c0
AV
378 error = -EFAULT;
379 else
380 error = count - buf.count;
1da177e4 381 }
63b6df14 382 fdput_pos(f);
1da177e4
LT
383 return error;
384}
0460b2a2
AV
385
386#ifdef CONFIG_COMPAT
387struct compat_old_linux_dirent {
388 compat_ulong_t d_ino;
389 compat_ulong_t d_offset;
390 unsigned short d_namlen;
391 char d_name[1];
392};
393
394struct compat_readdir_callback {
395 struct dir_context ctx;
396 struct compat_old_linux_dirent __user *dirent;
397 int result;
398};
399
400static int compat_fillonedir(struct dir_context *ctx, const char *name,
401 int namlen, loff_t offset, u64 ino,
402 unsigned int d_type)
403{
404 struct compat_readdir_callback *buf =
405 container_of(ctx, struct compat_readdir_callback, ctx);
406 struct compat_old_linux_dirent __user *dirent;
407 compat_ulong_t d_ino;
408
409 if (buf->result)
410 return -EINVAL;
0c93ac69
LT
411 buf->result = verify_dirent_name(name, namlen);
412 if (buf->result < 0)
413 return buf->result;
0460b2a2
AV
414 d_ino = ino;
415 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
416 buf->result = -EOVERFLOW;
417 return -EOVERFLOW;
418 }
419 buf->result++;
420 dirent = buf->dirent;
391b7461 421 if (!user_write_access_begin(dirent,
0460b2a2
AV
422 (unsigned long)(dirent->d_name + namlen + 1) -
423 (unsigned long)dirent))
424 goto efault;
391b7461
AV
425 unsafe_put_user(d_ino, &dirent->d_ino, efault_end);
426 unsafe_put_user(offset, &dirent->d_offset, efault_end);
427 unsafe_put_user(namlen, &dirent->d_namlen, efault_end);
428 unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
429 user_write_access_end();
0460b2a2 430 return 0;
391b7461
AV
431efault_end:
432 user_write_access_end();
0460b2a2
AV
433efault:
434 buf->result = -EFAULT;
435 return -EFAULT;
436}
437
438COMPAT_SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
439 struct compat_old_linux_dirent __user *, dirent, unsigned int, count)
440{
441 int error;
442 struct fd f = fdget_pos(fd);
443 struct compat_readdir_callback buf = {
444 .ctx.actor = compat_fillonedir,
445 .dirent = dirent
446 };
447
448 if (!f.file)
449 return -EBADF;
450
451 error = iterate_dir(f.file, &buf.ctx);
452 if (buf.result)
453 error = buf.result;
454
455 fdput_pos(f);
456 return error;
457}
458
459struct compat_linux_dirent {
460 compat_ulong_t d_ino;
461 compat_ulong_t d_off;
462 unsigned short d_reclen;
463 char d_name[1];
464};
465
466struct compat_getdents_callback {
467 struct dir_context ctx;
468 struct compat_linux_dirent __user *current_dir;
82af599b 469 int prev_reclen;
0460b2a2
AV
470 int count;
471 int error;
472};
473
474static int compat_filldir(struct dir_context *ctx, const char *name, int namlen,
475 loff_t offset, u64 ino, unsigned int d_type)
476{
82af599b 477 struct compat_linux_dirent __user *dirent, *prev;
0460b2a2
AV
478 struct compat_getdents_callback *buf =
479 container_of(ctx, struct compat_getdents_callback, ctx);
480 compat_ulong_t d_ino;
481 int reclen = ALIGN(offsetof(struct compat_linux_dirent, d_name) +
482 namlen + 2, sizeof(compat_long_t));
82af599b 483 int prev_reclen;
0460b2a2 484
82af599b
AV
485 buf->error = verify_dirent_name(name, namlen);
486 if (unlikely(buf->error))
487 return buf->error;
0460b2a2
AV
488 buf->error = -EINVAL; /* only used if we fail.. */
489 if (reclen > buf->count)
490 return -EINVAL;
491 d_ino = ino;
492 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
493 buf->error = -EOVERFLOW;
494 return -EOVERFLOW;
495 }
82af599b
AV
496 prev_reclen = buf->prev_reclen;
497 if (prev_reclen && signal_pending(current))
498 return -EINTR;
0460b2a2 499 dirent = buf->current_dir;
82af599b
AV
500 prev = (void __user *) dirent - prev_reclen;
501 if (!user_write_access_begin(prev, reclen + prev_reclen))
0460b2a2 502 goto efault;
82af599b
AV
503
504 unsafe_put_user(offset, &prev->d_off, efault_end);
505 unsafe_put_user(d_ino, &dirent->d_ino, efault_end);
506 unsafe_put_user(reclen, &dirent->d_reclen, efault_end);
507 unsafe_put_user(d_type, (char __user *) dirent + reclen - 1, efault_end);
508 unsafe_copy_dirent_name(dirent->d_name, name, namlen, efault_end);
509 user_write_access_end();
510
511 buf->prev_reclen = reclen;
512 buf->current_dir = (void __user *)dirent + reclen;
0460b2a2
AV
513 buf->count -= reclen;
514 return 0;
82af599b
AV
515efault_end:
516 user_write_access_end();
0460b2a2
AV
517efault:
518 buf->error = -EFAULT;
519 return -EFAULT;
520}
521
522COMPAT_SYSCALL_DEFINE3(getdents, unsigned int, fd,
523 struct compat_linux_dirent __user *, dirent, unsigned int, count)
524{
525 struct fd f;
0460b2a2
AV
526 struct compat_getdents_callback buf = {
527 .ctx.actor = compat_filldir,
528 .current_dir = dirent,
529 .count = count
530 };
531 int error;
532
0460b2a2
AV
533 f = fdget_pos(fd);
534 if (!f.file)
535 return -EBADF;
536
537 error = iterate_dir(f.file, &buf.ctx);
538 if (error >= 0)
539 error = buf.error;
82af599b
AV
540 if (buf.prev_reclen) {
541 struct compat_linux_dirent __user * lastdirent;
542 lastdirent = (void __user *)buf.current_dir - buf.prev_reclen;
543
0460b2a2
AV
544 if (put_user(buf.ctx.pos, &lastdirent->d_off))
545 error = -EFAULT;
546 else
547 error = count - buf.count;
548 }
549 fdput_pos(f);
550 return error;
551}
552#endif