1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/fs/readdir.c
4 *
5 * Copyright (C) 1995 Linus Torvalds
6 */
7
8#include <linux/stddef.h>
9#include <linux/kernel.h>
10#include <linux/export.h>
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>
16#include <linux/fs.h>
17#include <linux/fsnotify.h>
18#include <linux/dirent.h>
19#include <linux/security.h>
20#include <linux/syscalls.h>
21#include <linux/unistd.h>
22#include <linux/compat.h>
23
24#include <linux/uaccess.h>
25
26int iterate_dir(struct file *file, struct dir_context *ctx)
27{
28 struct inode *inode = file_inode(file);
29 bool shared = false;
30 int res = -ENOTDIR;
31 if (file->f_op->iterate_shared)
32 shared = true;
33 else if (!file->f_op->iterate)
34 goto out;
35
36 res = security_file_permission(file, MAY_READ);
37 if (res)
38 goto out;
39
40 if (shared)
41 res = down_read_killable(&inode->i_rwsem);
42 else
43 res = down_write_killable(&inode->i_rwsem);
44 if (res)
45 goto out;
46
47 res = -ENOENT;
48 if (!IS_DEADDIR(inode)) {
49 ctx->pos = file->f_pos;
50 if (shared)
51 res = file->f_op->iterate_shared(file, ctx);
52 else
53 res = file->f_op->iterate(file, ctx);
54 file->f_pos = ctx->pos;
55 fsnotify_access(file);
56 file_accessed(file);
57 }
58 if (shared)
59 inode_unlock_shared(inode);
60 else
61 inode_unlock(inode);
62out:
63 return res;
64}
65EXPORT_SYMBOL(iterate_dir);
66
67/*
68 * Traditional linux readdir() handling..
69 *
70 * "count=1" is a special case, meaning that the buffer is one
71 * dirent-structure in size and that the code can't handle more
72 * anyway. Thus the special "fillonedir()" function for that
73 * case (the low-level handlers don't need to care about this).
74 */
75
76#ifdef __ARCH_WANT_OLD_READDIR
77
78struct old_linux_dirent {
79 unsigned long d_ino;
80 unsigned long d_offset;
81 unsigned short d_namlen;
82 char d_name[1];
83};
84
85struct readdir_callback {
86 struct dir_context ctx;
87 struct old_linux_dirent __user * dirent;
88 int result;
89};
90
91static int fillonedir(struct dir_context *ctx, const char *name, int namlen,
92 loff_t offset, u64 ino, unsigned int d_type)
93{
94 struct readdir_callback *buf =
95 container_of(ctx, struct readdir_callback, ctx);
96 struct old_linux_dirent __user * dirent;
97 unsigned long d_ino;
98
99 if (buf->result)
100 return -EINVAL;
101 d_ino = ino;
102 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
103 buf->result = -EOVERFLOW;
104 return -EOVERFLOW;
105 }
106 buf->result++;
107 dirent = buf->dirent;
108 if (!access_ok(dirent,
109 (unsigned long)(dirent->d_name + namlen + 1) -
110 (unsigned long)dirent))
111 goto efault;
112 if ( __put_user(d_ino, &dirent->d_ino) ||
113 __put_user(offset, &dirent->d_offset) ||
114 __put_user(namlen, &dirent->d_namlen) ||
115 __copy_to_user(dirent->d_name, name, namlen) ||
116 __put_user(0, dirent->d_name + namlen))
117 goto efault;
118 return 0;
119efault:
120 buf->result = -EFAULT;
121 return -EFAULT;
122}
123
124SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
125 struct old_linux_dirent __user *, dirent, unsigned int, count)
126{
127 int error;
128 struct fd f = fdget_pos(fd);
129 struct readdir_callback buf = {
130 .ctx.actor = fillonedir,
131 .dirent = dirent
132 };
133
134 if (!f.file)
135 return -EBADF;
136
137 error = iterate_dir(f.file, &buf.ctx);
138 if (buf.result)
139 error = buf.result;
140
141 fdput_pos(f);
142 return error;
143}
144
145#endif /* __ARCH_WANT_OLD_READDIR */
146
147/*
148 * New, all-improved, singing, dancing, iBCS2-compliant getdents()
149 * interface.
150 */
151struct linux_dirent {
152 unsigned long d_ino;
153 unsigned long d_off;
154 unsigned short d_reclen;
155 char d_name[1];
156};
157
158struct getdents_callback {
159 struct dir_context ctx;
160 struct linux_dirent __user * current_dir;
161 struct linux_dirent __user * previous;
162 int count;
163 int error;
164};
165
166static int filldir(struct dir_context *ctx, const char *name, int namlen,
167 loff_t offset, u64 ino, unsigned int d_type)
168{
169 struct linux_dirent __user * dirent;
170 struct getdents_callback *buf =
171 container_of(ctx, struct getdents_callback, ctx);
172 unsigned long d_ino;
173 int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
174 sizeof(long));
175
176 buf->error = -EINVAL; /* only used if we fail.. */
177 if (reclen > buf->count)
178 return -EINVAL;
179 d_ino = ino;
180 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
181 buf->error = -EOVERFLOW;
182 return -EOVERFLOW;
183 }
184 dirent = buf->previous;
185 if (dirent) {
186 if (signal_pending(current))
187 return -EINTR;
188 if (__put_user(offset, &dirent->d_off))
189 goto efault;
190 }
191 dirent = buf->current_dir;
192 if (__put_user(d_ino, &dirent->d_ino))
193 goto efault;
194 if (__put_user(reclen, &dirent->d_reclen))
195 goto efault;
196 if (copy_to_user(dirent->d_name, name, namlen))
197 goto efault;
198 if (__put_user(0, dirent->d_name + namlen))
199 goto efault;
200 if (__put_user(d_type, (char __user *) dirent + reclen - 1))
201 goto efault;
202 buf->previous = dirent;
203 dirent = (void __user *)dirent + reclen;
204 buf->current_dir = dirent;
205 buf->count -= reclen;
206 return 0;
207efault:
208 buf->error = -EFAULT;
209 return -EFAULT;
210}
211
212SYSCALL_DEFINE3(getdents, unsigned int, fd,
213 struct linux_dirent __user *, dirent, unsigned int, count)
214{
215 struct fd f;
216 struct linux_dirent __user * lastdirent;
217 struct getdents_callback buf = {
218 .ctx.actor = filldir,
219 .count = count,
220 .current_dir = dirent
221 };
222 int error;
223
224 if (!access_ok(dirent, count))
225 return -EFAULT;
226
227 f = fdget_pos(fd);
228 if (!f.file)
229 return -EBADF;
230
231 error = iterate_dir(f.file, &buf.ctx);
232 if (error >= 0)
233 error = buf.error;
234 lastdirent = buf.previous;
235 if (lastdirent) {
236 if (put_user(buf.ctx.pos, &lastdirent->d_off))
237 error = -EFAULT;
238 else
239 error = count - buf.count;
240 }
241 fdput_pos(f);
242 return error;
243}
244
245struct getdents_callback64 {
246 struct dir_context ctx;
247 struct linux_dirent64 __user * current_dir;
248 struct linux_dirent64 __user * previous;
249 int count;
250 int error;
251};
252
253static int filldir64(struct dir_context *ctx, const char *name, int namlen,
254 loff_t offset, u64 ino, unsigned int d_type)
255{
256 struct linux_dirent64 __user *dirent;
257 struct getdents_callback64 *buf =
258 container_of(ctx, struct getdents_callback64, ctx);
259 int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
260 sizeof(u64));
261
262 buf->error = -EINVAL; /* only used if we fail.. */
263 if (reclen > buf->count)
264 return -EINVAL;
265 dirent = buf->previous;
266 if (dirent) {
267 if (signal_pending(current))
268 return -EINTR;
269 if (__put_user(offset, &dirent->d_off))
270 goto efault;
271 }
272 dirent = buf->current_dir;
273 if (__put_user(ino, &dirent->d_ino))
274 goto efault;
275 if (__put_user(0, &dirent->d_off))
276 goto efault;
277 if (__put_user(reclen, &dirent->d_reclen))
278 goto efault;
279 if (__put_user(d_type, &dirent->d_type))
280 goto efault;
281 if (copy_to_user(dirent->d_name, name, namlen))
282 goto efault;
283 if (__put_user(0, dirent->d_name + namlen))
284 goto efault;
285 buf->previous = dirent;
286 dirent = (void __user *)dirent + reclen;
287 buf->current_dir = dirent;
288 buf->count -= reclen;
289 return 0;
290efault:
291 buf->error = -EFAULT;
292 return -EFAULT;
293}
294
295int ksys_getdents64(unsigned int fd, struct linux_dirent64 __user *dirent,
296 unsigned int count)
297{
298 struct fd f;
299 struct linux_dirent64 __user * lastdirent;
300 struct getdents_callback64 buf = {
301 .ctx.actor = filldir64,
302 .count = count,
303 .current_dir = dirent
304 };
305 int error;
306
307 if (!access_ok(dirent, count))
308 return -EFAULT;
309
310 f = fdget_pos(fd);
311 if (!f.file)
312 return -EBADF;
313
314 error = iterate_dir(f.file, &buf.ctx);
315 if (error >= 0)
316 error = buf.error;
317 lastdirent = buf.previous;
318 if (lastdirent) {
319 typeof(lastdirent->d_off) d_off = buf.ctx.pos;
320 if (__put_user(d_off, &lastdirent->d_off))
321 error = -EFAULT;
322 else
323 error = count - buf.count;
324 }
325 fdput_pos(f);
326 return error;
327}
328
329
330SYSCALL_DEFINE3(getdents64, unsigned int, fd,
331 struct linux_dirent64 __user *, dirent, unsigned int, count)
332{
333 return ksys_getdents64(fd, dirent, count);
334}
335
336#ifdef CONFIG_COMPAT
337struct compat_old_linux_dirent {
338 compat_ulong_t d_ino;
339 compat_ulong_t d_offset;
340 unsigned short d_namlen;
341 char d_name[1];
342};
343
344struct compat_readdir_callback {
345 struct dir_context ctx;
346 struct compat_old_linux_dirent __user *dirent;
347 int result;
348};
349
350static int compat_fillonedir(struct dir_context *ctx, const char *name,
351 int namlen, loff_t offset, u64 ino,
352 unsigned int d_type)
353{
354 struct compat_readdir_callback *buf =
355 container_of(ctx, struct compat_readdir_callback, ctx);
356 struct compat_old_linux_dirent __user *dirent;
357 compat_ulong_t d_ino;
358
359 if (buf->result)
360 return -EINVAL;
361 d_ino = ino;
362 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
363 buf->result = -EOVERFLOW;
364 return -EOVERFLOW;
365 }
366 buf->result++;
367 dirent = buf->dirent;
368 if (!access_ok(dirent,
369 (unsigned long)(dirent->d_name + namlen + 1) -
370 (unsigned long)dirent))
371 goto efault;
372 if ( __put_user(d_ino, &dirent->d_ino) ||
373 __put_user(offset, &dirent->d_offset) ||
374 __put_user(namlen, &dirent->d_namlen) ||
375 __copy_to_user(dirent->d_name, name, namlen) ||
376 __put_user(0, dirent->d_name + namlen))
377 goto efault;
378 return 0;
379efault:
380 buf->result = -EFAULT;
381 return -EFAULT;
382}
383
384COMPAT_SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
385 struct compat_old_linux_dirent __user *, dirent, unsigned int, count)
386{
387 int error;
388 struct fd f = fdget_pos(fd);
389 struct compat_readdir_callback buf = {
390 .ctx.actor = compat_fillonedir,
391 .dirent = dirent
392 };
393
394 if (!f.file)
395 return -EBADF;
396
397 error = iterate_dir(f.file, &buf.ctx);
398 if (buf.result)
399 error = buf.result;
400
401 fdput_pos(f);
402 return error;
403}
404
405struct compat_linux_dirent {
406 compat_ulong_t d_ino;
407 compat_ulong_t d_off;
408 unsigned short d_reclen;
409 char d_name[1];
410};
411
412struct compat_getdents_callback {
413 struct dir_context ctx;
414 struct compat_linux_dirent __user *current_dir;
415 struct compat_linux_dirent __user *previous;
416 int count;
417 int error;
418};
419
420static int compat_filldir(struct dir_context *ctx, const char *name, int namlen,
421 loff_t offset, u64 ino, unsigned int d_type)
422{
423 struct compat_linux_dirent __user * dirent;
424 struct compat_getdents_callback *buf =
425 container_of(ctx, struct compat_getdents_callback, ctx);
426 compat_ulong_t d_ino;
427 int reclen = ALIGN(offsetof(struct compat_linux_dirent, d_name) +
428 namlen + 2, sizeof(compat_long_t));
429
430 buf->error = -EINVAL; /* only used if we fail.. */
431 if (reclen > buf->count)
432 return -EINVAL;
433 d_ino = ino;
434 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
435 buf->error = -EOVERFLOW;
436 return -EOVERFLOW;
437 }
438 dirent = buf->previous;
439 if (dirent) {
440 if (signal_pending(current))
441 return -EINTR;
442 if (__put_user(offset, &dirent->d_off))
443 goto efault;
444 }
445 dirent = buf->current_dir;
446 if (__put_user(d_ino, &dirent->d_ino))
447 goto efault;
448 if (__put_user(reclen, &dirent->d_reclen))
449 goto efault;
450 if (copy_to_user(dirent->d_name, name, namlen))
451 goto efault;
452 if (__put_user(0, dirent->d_name + namlen))
453 goto efault;
454 if (__put_user(d_type, (char __user *) dirent + reclen - 1))
455 goto efault;
456 buf->previous = dirent;
457 dirent = (void __user *)dirent + reclen;
458 buf->current_dir = dirent;
459 buf->count -= reclen;
460 return 0;
461efault:
462 buf->error = -EFAULT;
463 return -EFAULT;
464}
465
466COMPAT_SYSCALL_DEFINE3(getdents, unsigned int, fd,
467 struct compat_linux_dirent __user *, dirent, unsigned int, count)
468{
469 struct fd f;
470 struct compat_linux_dirent __user * lastdirent;
471 struct compat_getdents_callback buf = {
472 .ctx.actor = compat_filldir,
473 .current_dir = dirent,
474 .count = count
475 };
476 int error;
477
478 if (!access_ok(dirent, count))
479 return -EFAULT;
480
481 f = fdget_pos(fd);
482 if (!f.file)
483 return -EBADF;
484
485 error = iterate_dir(f.file, &buf.ctx);
486 if (error >= 0)
487 error = buf.error;
488 lastdirent = buf.previous;
489 if (lastdirent) {
490 if (put_user(buf.ctx.pos, &lastdirent->d_off))
491 error = -EFAULT;
492 else
493 error = count - buf.count;
494 }
495 fdput_pos(f);
496 return error;
497}
498#endif
499