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1/*
2 * linux/fs/readdir.c
3 *
4 * Copyright (C) 1995 Linus Torvalds
5 */
6
7#include <linux/stddef.h>
8#include <linux/kernel.h>
9#include <linux/export.h>
10#include <linux/time.h>
11#include <linux/mm.h>
12#include <linux/errno.h>
13#include <linux/stat.h>
14#include <linux/file.h>
15#include <linux/fs.h>
16#include <linux/fsnotify.h>
17#include <linux/dirent.h>
18#include <linux/security.h>
19#include <linux/syscalls.h>
20#include <linux/unistd.h>
21
22#include <linux/uaccess.h>
23
24int iterate_dir(struct file *file, struct dir_context *ctx)
25{
26 struct inode *inode = file_inode(file);
27 bool shared = false;
28 int res = -ENOTDIR;
29 if (file->f_op->iterate_shared)
30 shared = true;
31 else if (!file->f_op->iterate)
32 goto out;
33
34 res = security_file_permission(file, MAY_READ);
35 if (res)
36 goto out;
37
38 if (shared) {
39 inode_lock_shared(inode);
40 } else {
41 res = down_write_killable(&inode->i_rwsem);
42 if (res)
43 goto out;
44 }
45
46 res = -ENOENT;
47 if (!IS_DEADDIR(inode)) {
48 ctx->pos = file->f_pos;
49 if (shared)
50 res = file->f_op->iterate_shared(file, ctx);
51 else
52 res = file->f_op->iterate(file, ctx);
53 file->f_pos = ctx->pos;
54 fsnotify_access(file);
55 file_accessed(file);
56 }
57 if (shared)
58 inode_unlock_shared(inode);
59 else
60 inode_unlock(inode);
61out:
62 return res;
63}
64EXPORT_SYMBOL(iterate_dir);
65
66/*
67 * Traditional linux readdir() handling..
68 *
69 * "count=1" is a special case, meaning that the buffer is one
70 * dirent-structure in size and that the code can't handle more
71 * anyway. Thus the special "fillonedir()" function for that
72 * case (the low-level handlers don't need to care about this).
73 */
74
75#ifdef __ARCH_WANT_OLD_READDIR
76
77struct old_linux_dirent {
78 unsigned long d_ino;
79 unsigned long d_offset;
80 unsigned short d_namlen;
81 char d_name[1];
82};
83
84struct readdir_callback {
85 struct dir_context ctx;
86 struct old_linux_dirent __user * dirent;
87 int result;
88};
89
90static int fillonedir(struct dir_context *ctx, const char *name, int namlen,
91 loff_t offset, u64 ino, unsigned int d_type)
92{
93 struct readdir_callback *buf =
94 container_of(ctx, struct readdir_callback, ctx);
95 struct old_linux_dirent __user * dirent;
96 unsigned long d_ino;
97
98 if (buf->result)
99 return -EINVAL;
100 d_ino = ino;
101 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
102 buf->result = -EOVERFLOW;
103 return -EOVERFLOW;
104 }
105 buf->result++;
106 dirent = buf->dirent;
107 if (!access_ok(VERIFY_WRITE, dirent,
108 (unsigned long)(dirent->d_name + namlen + 1) -
109 (unsigned long)dirent))
110 goto efault;
111 if ( __put_user(d_ino, &dirent->d_ino) ||
112 __put_user(offset, &dirent->d_offset) ||
113 __put_user(namlen, &dirent->d_namlen) ||
114 __copy_to_user(dirent->d_name, name, namlen) ||
115 __put_user(0, dirent->d_name + namlen))
116 goto efault;
117 return 0;
118efault:
119 buf->result = -EFAULT;
120 return -EFAULT;
121}
122
123SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
124 struct old_linux_dirent __user *, dirent, unsigned int, count)
125{
126 int error;
127 struct fd f = fdget_pos(fd);
128 struct readdir_callback buf = {
129 .ctx.actor = fillonedir,
130 .dirent = dirent
131 };
132
133 if (!f.file)
134 return -EBADF;
135
136 error = iterate_dir(f.file, &buf.ctx);
137 if (buf.result)
138 error = buf.result;
139
140 fdput_pos(f);
141 return error;
142}
143
144#endif /* __ARCH_WANT_OLD_READDIR */
145
146/*
147 * New, all-improved, singing, dancing, iBCS2-compliant getdents()
148 * interface.
149 */
150struct linux_dirent {
151 unsigned long d_ino;
152 unsigned long d_off;
153 unsigned short d_reclen;
154 char d_name[1];
155};
156
157struct getdents_callback {
158 struct dir_context ctx;
159 struct linux_dirent __user * current_dir;
160 struct linux_dirent __user * previous;
161 int count;
162 int error;
163};
164
165static int filldir(struct dir_context *ctx, const char *name, int namlen,
166 loff_t offset, u64 ino, unsigned int d_type)
167{
168 struct linux_dirent __user * dirent;
169 struct getdents_callback *buf =
170 container_of(ctx, struct getdents_callback, ctx);
171 unsigned long d_ino;
172 int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
173 sizeof(long));
174
175 buf->error = -EINVAL; /* only used if we fail.. */
176 if (reclen > buf->count)
177 return -EINVAL;
178 d_ino = ino;
179 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
180 buf->error = -EOVERFLOW;
181 return -EOVERFLOW;
182 }
183 dirent = buf->previous;
184 if (dirent) {
185 if (signal_pending(current))
186 return -EINTR;
187 if (__put_user(offset, &dirent->d_off))
188 goto efault;
189 }
190 dirent = buf->current_dir;
191 if (__put_user(d_ino, &dirent->d_ino))
192 goto efault;
193 if (__put_user(reclen, &dirent->d_reclen))
194 goto efault;
195 if (copy_to_user(dirent->d_name, name, namlen))
196 goto efault;
197 if (__put_user(0, dirent->d_name + namlen))
198 goto efault;
199 if (__put_user(d_type, (char __user *) dirent + reclen - 1))
200 goto efault;
201 buf->previous = dirent;
202 dirent = (void __user *)dirent + reclen;
203 buf->current_dir = dirent;
204 buf->count -= reclen;
205 return 0;
206efault:
207 buf->error = -EFAULT;
208 return -EFAULT;
209}
210
211SYSCALL_DEFINE3(getdents, unsigned int, fd,
212 struct linux_dirent __user *, dirent, unsigned int, count)
213{
214 struct fd f;
215 struct linux_dirent __user * lastdirent;
216 struct getdents_callback buf = {
217 .ctx.actor = filldir,
218 .count = count,
219 .current_dir = dirent
220 };
221 int error;
222
223 if (!access_ok(VERIFY_WRITE, dirent, count))
224 return -EFAULT;
225
226 f = fdget_pos(fd);
227 if (!f.file)
228 return -EBADF;
229
230 error = iterate_dir(f.file, &buf.ctx);
231 if (error >= 0)
232 error = buf.error;
233 lastdirent = buf.previous;
234 if (lastdirent) {
235 if (put_user(buf.ctx.pos, &lastdirent->d_off))
236 error = -EFAULT;
237 else
238 error = count - buf.count;
239 }
240 fdput_pos(f);
241 return error;
242}
243
244struct getdents_callback64 {
245 struct dir_context ctx;
246 struct linux_dirent64 __user * current_dir;
247 struct linux_dirent64 __user * previous;
248 int count;
249 int error;
250};
251
252static int filldir64(struct dir_context *ctx, const char *name, int namlen,
253 loff_t offset, u64 ino, unsigned int d_type)
254{
255 struct linux_dirent64 __user *dirent;
256 struct getdents_callback64 *buf =
257 container_of(ctx, struct getdents_callback64, ctx);
258 int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
259 sizeof(u64));
260
261 buf->error = -EINVAL; /* only used if we fail.. */
262 if (reclen > buf->count)
263 return -EINVAL;
264 dirent = buf->previous;
265 if (dirent) {
266 if (signal_pending(current))
267 return -EINTR;
268 if (__put_user(offset, &dirent->d_off))
269 goto efault;
270 }
271 dirent = buf->current_dir;
272 if (__put_user(ino, &dirent->d_ino))
273 goto efault;
274 if (__put_user(0, &dirent->d_off))
275 goto efault;
276 if (__put_user(reclen, &dirent->d_reclen))
277 goto efault;
278 if (__put_user(d_type, &dirent->d_type))
279 goto efault;
280 if (copy_to_user(dirent->d_name, name, namlen))
281 goto efault;
282 if (__put_user(0, dirent->d_name + namlen))
283 goto efault;
284 buf->previous = dirent;
285 dirent = (void __user *)dirent + reclen;
286 buf->current_dir = dirent;
287 buf->count -= reclen;
288 return 0;
289efault:
290 buf->error = -EFAULT;
291 return -EFAULT;
292}
293
294SYSCALL_DEFINE3(getdents64, unsigned int, fd,
295 struct linux_dirent64 __user *, dirent, unsigned int, count)
296{
297 struct fd f;
298 struct linux_dirent64 __user * lastdirent;
299 struct getdents_callback64 buf = {
300 .ctx.actor = filldir64,
301 .count = count,
302 .current_dir = dirent
303 };
304 int error;
305
306 if (!access_ok(VERIFY_WRITE, dirent, count))
307 return -EFAULT;
308
309 f = fdget_pos(fd);
310 if (!f.file)
311 return -EBADF;
312
313 error = iterate_dir(f.file, &buf.ctx);
314 if (error >= 0)
315 error = buf.error;
316 lastdirent = buf.previous;
317 if (lastdirent) {
318 typeof(lastdirent->d_off) d_off = buf.ctx.pos;
319 if (__put_user(d_off, &lastdirent->d_off))
320 error = -EFAULT;
321 else
322 error = count - buf.count;
323 }
324 fdput_pos(f);
325 return error;
326}
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#include <linux/uaccess.h>
24
25#include <asm/unaligned.h>
26
27/*
28 * Note the "unsafe_put_user() semantics: we goto a
29 * label for errors.
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); \
35 unsafe_put_user(0, dst+len, label); \
36 unsafe_copy_to_user(dst, src, len, label); \
37} while (0)
38
39
40int iterate_dir(struct file *file, struct dir_context *ctx)
41{
42 struct inode *inode = file_inode(file);
43 bool shared = false;
44 int res = -ENOTDIR;
45 if (file->f_op->iterate_shared)
46 shared = true;
47 else if (!file->f_op->iterate)
48 goto out;
49
50 res = security_file_permission(file, MAY_READ);
51 if (res)
52 goto out;
53
54 if (shared)
55 res = down_read_killable(&inode->i_rwsem);
56 else
57 res = down_write_killable(&inode->i_rwsem);
58 if (res)
59 goto out;
60
61 res = -ENOENT;
62 if (!IS_DEADDIR(inode)) {
63 ctx->pos = file->f_pos;
64 if (shared)
65 res = file->f_op->iterate_shared(file, ctx);
66 else
67 res = file->f_op->iterate(file, ctx);
68 file->f_pos = ctx->pos;
69 fsnotify_access(file);
70 file_accessed(file);
71 }
72 if (shared)
73 inode_unlock_shared(inode);
74 else
75 inode_unlock(inode);
76out:
77 return res;
78}
79EXPORT_SYMBOL(iterate_dir);
80
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.
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.
109 */
110static int verify_dirent_name(const char *name, int len)
111{
112 if (len <= 0 || len >= PATH_MAX)
113 return -EIO;
114 if (memchr(name, '/', len))
115 return -EIO;
116 return 0;
117}
118
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 */
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 {
138 struct dir_context ctx;
139 struct old_linux_dirent __user * dirent;
140 int result;
141};
142
143static bool fillonedir(struct dir_context *ctx, const char *name, int namlen,
144 loff_t offset, u64 ino, unsigned int d_type)
145{
146 struct readdir_callback *buf =
147 container_of(ctx, struct readdir_callback, ctx);
148 struct old_linux_dirent __user * dirent;
149 unsigned long d_ino;
150
151 if (buf->result)
152 return false;
153 buf->result = verify_dirent_name(name, namlen);
154 if (buf->result)
155 return false;
156 d_ino = ino;
157 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
158 buf->result = -EOVERFLOW;
159 return false;
160 }
161 buf->result++;
162 dirent = buf->dirent;
163 if (!user_write_access_begin(dirent,
164 (unsigned long)(dirent->d_name + namlen + 1) -
165 (unsigned long)dirent))
166 goto efault;
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();
172 return true;
173efault_end:
174 user_write_access_end();
175efault:
176 buf->result = -EFAULT;
177 return false;
178}
179
180SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
181 struct old_linux_dirent __user *, dirent, unsigned int, count)
182{
183 int error;
184 struct fd f = fdget_pos(fd);
185 struct readdir_callback buf = {
186 .ctx.actor = fillonedir,
187 .dirent = dirent
188 };
189
190 if (!f.file)
191 return -EBADF;
192
193 error = iterate_dir(f.file, &buf.ctx);
194 if (buf.result)
195 error = buf.result;
196
197 fdput_pos(f);
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 {
215 struct dir_context ctx;
216 struct linux_dirent __user * current_dir;
217 int prev_reclen;
218 int count;
219 int error;
220};
221
222static bool filldir(struct dir_context *ctx, const char *name, int namlen,
223 loff_t offset, u64 ino, unsigned int d_type)
224{
225 struct linux_dirent __user *dirent, *prev;
226 struct getdents_callback *buf =
227 container_of(ctx, struct getdents_callback, ctx);
228 unsigned long d_ino;
229 int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
230 sizeof(long));
231 int prev_reclen;
232
233 buf->error = verify_dirent_name(name, namlen);
234 if (unlikely(buf->error))
235 return false;
236 buf->error = -EINVAL; /* only used if we fail.. */
237 if (reclen > buf->count)
238 return false;
239 d_ino = ino;
240 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
241 buf->error = -EOVERFLOW;
242 return false;
243 }
244 prev_reclen = buf->prev_reclen;
245 if (prev_reclen && signal_pending(current))
246 return false;
247 dirent = buf->current_dir;
248 prev = (void __user *) dirent - prev_reclen;
249 if (!user_write_access_begin(prev, reclen + prev_reclen))
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);
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);
258 user_write_access_end();
259
260 buf->current_dir = (void __user *)dirent + reclen;
261 buf->prev_reclen = reclen;
262 buf->count -= reclen;
263 return true;
264efault_end:
265 user_write_access_end();
266efault:
267 buf->error = -EFAULT;
268 return false;
269}
270
271SYSCALL_DEFINE3(getdents, unsigned int, fd,
272 struct linux_dirent __user *, dirent, unsigned int, count)
273{
274 struct fd f;
275 struct getdents_callback buf = {
276 .ctx.actor = filldir,
277 .count = count,
278 .current_dir = dirent
279 };
280 int error;
281
282 f = fdget_pos(fd);
283 if (!f.file)
284 return -EBADF;
285
286 error = iterate_dir(f.file, &buf.ctx);
287 if (error >= 0)
288 error = buf.error;
289 if (buf.prev_reclen) {
290 struct linux_dirent __user * lastdirent;
291 lastdirent = (void __user *)buf.current_dir - buf.prev_reclen;
292
293 if (put_user(buf.ctx.pos, &lastdirent->d_off))
294 error = -EFAULT;
295 else
296 error = count - buf.count;
297 }
298 fdput_pos(f);
299 return error;
300}
301
302struct getdents_callback64 {
303 struct dir_context ctx;
304 struct linux_dirent64 __user * current_dir;
305 int prev_reclen;
306 int count;
307 int error;
308};
309
310static bool filldir64(struct dir_context *ctx, const char *name, int namlen,
311 loff_t offset, u64 ino, unsigned int d_type)
312{
313 struct linux_dirent64 __user *dirent, *prev;
314 struct getdents_callback64 *buf =
315 container_of(ctx, struct getdents_callback64, ctx);
316 int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
317 sizeof(u64));
318 int prev_reclen;
319
320 buf->error = verify_dirent_name(name, namlen);
321 if (unlikely(buf->error))
322 return false;
323 buf->error = -EINVAL; /* only used if we fail.. */
324 if (reclen > buf->count)
325 return false;
326 prev_reclen = buf->prev_reclen;
327 if (prev_reclen && signal_pending(current))
328 return false;
329 dirent = buf->current_dir;
330 prev = (void __user *)dirent - prev_reclen;
331 if (!user_write_access_begin(prev, reclen + prev_reclen))
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);
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);
340 user_write_access_end();
341
342 buf->prev_reclen = reclen;
343 buf->current_dir = (void __user *)dirent + reclen;
344 buf->count -= reclen;
345 return true;
346
347efault_end:
348 user_write_access_end();
349efault:
350 buf->error = -EFAULT;
351 return false;
352}
353
354SYSCALL_DEFINE3(getdents64, unsigned int, fd,
355 struct linux_dirent64 __user *, dirent, unsigned int, count)
356{
357 struct fd f;
358 struct getdents_callback64 buf = {
359 .ctx.actor = filldir64,
360 .count = count,
361 .current_dir = dirent
362 };
363 int error;
364
365 f = fdget_pos(fd);
366 if (!f.file)
367 return -EBADF;
368
369 error = iterate_dir(f.file, &buf.ctx);
370 if (error >= 0)
371 error = buf.error;
372 if (buf.prev_reclen) {
373 struct linux_dirent64 __user * lastdirent;
374 typeof(lastdirent->d_off) d_off = buf.ctx.pos;
375
376 lastdirent = (void __user *) buf.current_dir - buf.prev_reclen;
377 if (put_user(d_off, &lastdirent->d_off))
378 error = -EFAULT;
379 else
380 error = count - buf.count;
381 }
382 fdput_pos(f);
383 return error;
384}
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 bool 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 false;
411 buf->result = verify_dirent_name(name, namlen);
412 if (buf->result)
413 return false;
414 d_ino = ino;
415 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
416 buf->result = -EOVERFLOW;
417 return false;
418 }
419 buf->result++;
420 dirent = buf->dirent;
421 if (!user_write_access_begin(dirent,
422 (unsigned long)(dirent->d_name + namlen + 1) -
423 (unsigned long)dirent))
424 goto efault;
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();
430 return true;
431efault_end:
432 user_write_access_end();
433efault:
434 buf->result = -EFAULT;
435 return false;
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;
469 int prev_reclen;
470 int count;
471 int error;
472};
473
474static bool compat_filldir(struct dir_context *ctx, const char *name, int namlen,
475 loff_t offset, u64 ino, unsigned int d_type)
476{
477 struct compat_linux_dirent __user *dirent, *prev;
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));
483 int prev_reclen;
484
485 buf->error = verify_dirent_name(name, namlen);
486 if (unlikely(buf->error))
487 return false;
488 buf->error = -EINVAL; /* only used if we fail.. */
489 if (reclen > buf->count)
490 return false;
491 d_ino = ino;
492 if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
493 buf->error = -EOVERFLOW;
494 return false;
495 }
496 prev_reclen = buf->prev_reclen;
497 if (prev_reclen && signal_pending(current))
498 return false;
499 dirent = buf->current_dir;
500 prev = (void __user *) dirent - prev_reclen;
501 if (!user_write_access_begin(prev, reclen + prev_reclen))
502 goto efault;
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;
513 buf->count -= reclen;
514 return true;
515efault_end:
516 user_write_access_end();
517efault:
518 buf->error = -EFAULT;
519 return false;
520}
521
522COMPAT_SYSCALL_DEFINE3(getdents, unsigned int, fd,
523 struct compat_linux_dirent __user *, dirent, unsigned int, count)
524{
525 struct fd f;
526 struct compat_getdents_callback buf = {
527 .ctx.actor = compat_filldir,
528 .current_dir = dirent,
529 .count = count
530 };
531 int error;
532
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;
540 if (buf.prev_reclen) {
541 struct compat_linux_dirent __user * lastdirent;
542 lastdirent = (void __user *)buf.current_dir - buf.prev_reclen;
543
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