Commit | Line | Data |
---|---|---|
e9be9d5e MS |
1 | /* |
2 | * | |
3 | * Copyright (C) 2011 Novell Inc. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify it | |
6 | * under the terms of the GNU General Public License version 2 as published by | |
7 | * the Free Software Foundation. | |
8 | */ | |
9 | ||
10 | #include <linux/fs.h> | |
11 | #include <linux/slab.h> | |
5b825c3a | 12 | #include <linux/cred.h> |
e9be9d5e | 13 | #include <linux/xattr.h> |
5201dc44 | 14 | #include <linux/posix_acl.h> |
5f8415d6 | 15 | #include <linux/ratelimit.h> |
e9be9d5e MS |
16 | #include "overlayfs.h" |
17 | ||
e9be9d5e MS |
18 | int ovl_setattr(struct dentry *dentry, struct iattr *attr) |
19 | { | |
20 | int err; | |
21 | struct dentry *upperdentry; | |
1175b6b8 | 22 | const struct cred *old_cred; |
e9be9d5e | 23 | |
cf9a6784 MS |
24 | /* |
25 | * Check for permissions before trying to copy-up. This is redundant | |
26 | * since it will be rechecked later by ->setattr() on upper dentry. But | |
27 | * without this, copy-up can be triggered by just about anybody. | |
28 | * | |
29 | * We don't initialize inode->size, which just means that | |
30 | * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not | |
31 | * check for a swapfile (which this won't be anyway). | |
32 | */ | |
31051c85 | 33 | err = setattr_prepare(dentry, attr); |
cf9a6784 MS |
34 | if (err) |
35 | return err; | |
36 | ||
e9be9d5e MS |
37 | err = ovl_want_write(dentry); |
38 | if (err) | |
39 | goto out; | |
40 | ||
acff81ec MS |
41 | err = ovl_copy_up(dentry); |
42 | if (!err) { | |
43 | upperdentry = ovl_dentry_upper(dentry); | |
44 | ||
b99c2d91 MS |
45 | if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) |
46 | attr->ia_valid &= ~ATTR_MODE; | |
47 | ||
5955102c | 48 | inode_lock(upperdentry->d_inode); |
1175b6b8 | 49 | old_cred = ovl_override_creds(dentry->d_sb); |
e9be9d5e | 50 | err = notify_change(upperdentry, attr, NULL); |
1175b6b8 | 51 | revert_creds(old_cred); |
b81de061 KK |
52 | if (!err) |
53 | ovl_copyattr(upperdentry->d_inode, dentry->d_inode); | |
5955102c | 54 | inode_unlock(upperdentry->d_inode); |
e9be9d5e MS |
55 | } |
56 | ovl_drop_write(dentry); | |
57 | out: | |
58 | return err; | |
59 | } | |
60 | ||
5b712091 MS |
61 | int ovl_getattr(const struct path *path, struct kstat *stat, |
62 | u32 request_mask, unsigned int flags) | |
e9be9d5e | 63 | { |
a528d35e | 64 | struct dentry *dentry = path->dentry; |
72b608f0 | 65 | enum ovl_path_type type; |
e9be9d5e | 66 | struct path realpath; |
1175b6b8 | 67 | const struct cred *old_cred; |
5b712091 | 68 | bool is_dir = S_ISDIR(dentry->d_inode->i_mode); |
1175b6b8 | 69 | int err; |
e9be9d5e | 70 | |
72b608f0 | 71 | type = ovl_path_real(dentry, &realpath); |
1175b6b8 | 72 | old_cred = ovl_override_creds(dentry->d_sb); |
a528d35e | 73 | err = vfs_getattr(&realpath, stat, request_mask, flags); |
72b608f0 AG |
74 | if (err) |
75 | goto out; | |
76 | ||
77 | /* | |
78 | * When all layers are on the same fs, all real inode number are | |
79 | * unique, so we use the overlay st_dev, which is friendly to du -x. | |
80 | * | |
81 | * We also use st_ino of the copy up origin, if we know it. | |
82 | * This guaranties constant st_dev/st_ino across copy up. | |
83 | * | |
84 | * If filesystem supports NFS export ops, this also guaranties | |
85 | * persistent st_ino across mount cycle. | |
86 | */ | |
87 | if (ovl_same_sb(dentry->d_sb)) { | |
88 | if (OVL_TYPE_ORIGIN(type)) { | |
89 | struct kstat lowerstat; | |
5b712091 | 90 | u32 lowermask = STATX_INO | (!is_dir ? STATX_NLINK : 0); |
72b608f0 AG |
91 | |
92 | ovl_path_lower(dentry, &realpath); | |
93 | err = vfs_getattr(&realpath, &lowerstat, | |
5b712091 | 94 | lowermask, flags); |
72b608f0 AG |
95 | if (err) |
96 | goto out; | |
97 | ||
98 | WARN_ON_ONCE(stat->dev != lowerstat.dev); | |
99 | /* | |
359f392c | 100 | * Lower hardlinks may be broken on copy up to different |
72b608f0 AG |
101 | * upper files, so we cannot use the lower origin st_ino |
102 | * for those different files, even for the same fs case. | |
359f392c AG |
103 | * With inodes index enabled, it is safe to use st_ino |
104 | * of an indexed hardlinked origin. The index validates | |
105 | * that the upper hardlink is not broken. | |
72b608f0 | 106 | */ |
359f392c AG |
107 | if (is_dir || lowerstat.nlink == 1 || |
108 | ovl_test_flag(OVL_INDEX, d_inode(dentry))) | |
72b608f0 AG |
109 | stat->ino = lowerstat.ino; |
110 | } | |
111 | stat->dev = dentry->d_sb->s_dev; | |
5b712091 MS |
112 | } else if (is_dir) { |
113 | /* | |
114 | * If not all layers are on the same fs the pair {real st_ino; | |
115 | * overlay st_dev} is not unique, so use the non persistent | |
116 | * overlay st_ino. | |
117 | * | |
118 | * Always use the overlay st_dev for directories, so 'find | |
119 | * -xdev' will scan the entire overlay mount and won't cross the | |
120 | * overlay mount boundaries. | |
121 | */ | |
122 | stat->dev = dentry->d_sb->s_dev; | |
123 | stat->ino = dentry->d_inode->i_ino; | |
72b608f0 | 124 | } |
5b712091 MS |
125 | |
126 | /* | |
127 | * It's probably not worth it to count subdirs to get the | |
128 | * correct link count. nlink=1 seems to pacify 'find' and | |
129 | * other utilities. | |
130 | */ | |
131 | if (is_dir && OVL_TYPE_MERGE(type)) | |
132 | stat->nlink = 1; | |
133 | ||
5f8415d6 AG |
134 | /* |
135 | * Return the overlay inode nlinks for indexed upper inodes. | |
136 | * Overlay inode nlink counts the union of the upper hardlinks | |
137 | * and non-covered lower hardlinks. It does not include the upper | |
138 | * index hardlink. | |
139 | */ | |
140 | if (!is_dir && ovl_test_flag(OVL_INDEX, d_inode(dentry))) | |
141 | stat->nlink = dentry->d_inode->i_nlink; | |
142 | ||
72b608f0 | 143 | out: |
1175b6b8 | 144 | revert_creds(old_cred); |
72b608f0 | 145 | |
1175b6b8 | 146 | return err; |
e9be9d5e MS |
147 | } |
148 | ||
149 | int ovl_permission(struct inode *inode, int mask) | |
150 | { | |
09d8b586 MS |
151 | struct inode *upperinode = ovl_inode_upper(inode); |
152 | struct inode *realinode = upperinode ?: ovl_inode_lower(inode); | |
c0ca3d70 | 153 | const struct cred *old_cred; |
e9be9d5e MS |
154 | int err; |
155 | ||
e9be9d5e | 156 | /* Careful in RCU walk mode */ |
e9be9d5e MS |
157 | if (!realinode) { |
158 | WARN_ON(!(mask & MAY_NOT_BLOCK)); | |
a999d7e1 | 159 | return -ECHILD; |
e9be9d5e MS |
160 | } |
161 | ||
c0ca3d70 VG |
162 | /* |
163 | * Check overlay inode with the creds of task and underlying inode | |
164 | * with creds of mounter | |
165 | */ | |
166 | err = generic_permission(inode, mask); | |
167 | if (err) | |
168 | return err; | |
169 | ||
170 | old_cred = ovl_override_creds(inode->i_sb); | |
09d8b586 MS |
171 | if (!upperinode && |
172 | !special_file(realinode->i_mode) && mask & MAY_WRITE) { | |
754f8cb7 | 173 | mask &= ~(MAY_WRITE | MAY_APPEND); |
500cac3c VG |
174 | /* Make sure mounter can read file for copy up later */ |
175 | mask |= MAY_READ; | |
176 | } | |
9c630ebe | 177 | err = inode_permission(realinode, mask); |
c0ca3d70 VG |
178 | revert_creds(old_cred); |
179 | ||
180 | return err; | |
e9be9d5e MS |
181 | } |
182 | ||
6b255391 | 183 | static const char *ovl_get_link(struct dentry *dentry, |
fceef393 AV |
184 | struct inode *inode, |
185 | struct delayed_call *done) | |
e9be9d5e | 186 | { |
1175b6b8 VG |
187 | const struct cred *old_cred; |
188 | const char *p; | |
e9be9d5e | 189 | |
6b255391 AV |
190 | if (!dentry) |
191 | return ERR_PTR(-ECHILD); | |
192 | ||
1175b6b8 | 193 | old_cred = ovl_override_creds(dentry->d_sb); |
7764235b | 194 | p = vfs_get_link(ovl_dentry_real(dentry), done); |
1175b6b8 VG |
195 | revert_creds(old_cred); |
196 | return p; | |
e9be9d5e MS |
197 | } |
198 | ||
0956254a | 199 | bool ovl_is_private_xattr(const char *name) |
e9be9d5e | 200 | { |
fe2b7595 AG |
201 | return strncmp(name, OVL_XATTR_PREFIX, |
202 | sizeof(OVL_XATTR_PREFIX) - 1) == 0; | |
e9be9d5e MS |
203 | } |
204 | ||
0e585ccc AG |
205 | int ovl_xattr_set(struct dentry *dentry, const char *name, const void *value, |
206 | size_t size, int flags) | |
e9be9d5e MS |
207 | { |
208 | int err; | |
0e585ccc AG |
209 | struct path realpath; |
210 | enum ovl_path_type type = ovl_path_real(dentry, &realpath); | |
1175b6b8 | 211 | const struct cred *old_cred; |
e9be9d5e MS |
212 | |
213 | err = ovl_want_write(dentry); | |
214 | if (err) | |
215 | goto out; | |
216 | ||
0e585ccc AG |
217 | if (!value && !OVL_TYPE_UPPER(type)) { |
218 | err = vfs_getxattr(realpath.dentry, name, NULL, 0); | |
219 | if (err < 0) | |
220 | goto out_drop_write; | |
221 | } | |
222 | ||
e9be9d5e MS |
223 | err = ovl_copy_up(dentry); |
224 | if (err) | |
225 | goto out_drop_write; | |
226 | ||
0e585ccc AG |
227 | if (!OVL_TYPE_UPPER(type)) |
228 | ovl_path_upper(dentry, &realpath); | |
229 | ||
1175b6b8 | 230 | old_cred = ovl_override_creds(dentry->d_sb); |
0e585ccc AG |
231 | if (value) |
232 | err = vfs_setxattr(realpath.dentry, name, value, size, flags); | |
233 | else { | |
234 | WARN_ON(flags != XATTR_REPLACE); | |
235 | err = vfs_removexattr(realpath.dentry, name); | |
236 | } | |
1175b6b8 | 237 | revert_creds(old_cred); |
e9be9d5e MS |
238 | |
239 | out_drop_write: | |
240 | ovl_drop_write(dentry); | |
241 | out: | |
242 | return err; | |
243 | } | |
244 | ||
0eb45fc3 AG |
245 | int ovl_xattr_get(struct dentry *dentry, const char *name, |
246 | void *value, size_t size) | |
e9be9d5e | 247 | { |
b581755b | 248 | struct dentry *realdentry = ovl_dentry_real(dentry); |
1175b6b8 VG |
249 | ssize_t res; |
250 | const struct cred *old_cred; | |
52148463 | 251 | |
1175b6b8 VG |
252 | old_cred = ovl_override_creds(dentry->d_sb); |
253 | res = vfs_getxattr(realdentry, name, value, size); | |
254 | revert_creds(old_cred); | |
255 | return res; | |
e9be9d5e MS |
256 | } |
257 | ||
a082c6f6 MS |
258 | static bool ovl_can_list(const char *s) |
259 | { | |
260 | /* List all non-trusted xatts */ | |
261 | if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0) | |
262 | return true; | |
263 | ||
264 | /* Never list trusted.overlay, list other trusted for superuser only */ | |
265 | return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN); | |
266 | } | |
267 | ||
e9be9d5e MS |
268 | ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) |
269 | { | |
b581755b | 270 | struct dentry *realdentry = ovl_dentry_real(dentry); |
e9be9d5e | 271 | ssize_t res; |
7cb35119 MS |
272 | size_t len; |
273 | char *s; | |
1175b6b8 | 274 | const struct cred *old_cred; |
e9be9d5e | 275 | |
1175b6b8 | 276 | old_cred = ovl_override_creds(dentry->d_sb); |
b581755b | 277 | res = vfs_listxattr(realdentry, list, size); |
1175b6b8 | 278 | revert_creds(old_cred); |
e9be9d5e MS |
279 | if (res <= 0 || size == 0) |
280 | return res; | |
281 | ||
e9be9d5e | 282 | /* filter out private xattrs */ |
7cb35119 MS |
283 | for (s = list, len = res; len;) { |
284 | size_t slen = strnlen(s, len) + 1; | |
e9be9d5e | 285 | |
7cb35119 MS |
286 | /* underlying fs providing us with an broken xattr list? */ |
287 | if (WARN_ON(slen > len)) | |
288 | return -EIO; | |
e9be9d5e | 289 | |
7cb35119 | 290 | len -= slen; |
a082c6f6 | 291 | if (!ovl_can_list(s)) { |
e9be9d5e | 292 | res -= slen; |
7cb35119 | 293 | memmove(s, s + slen, len); |
e9be9d5e | 294 | } else { |
7cb35119 | 295 | s += slen; |
e9be9d5e MS |
296 | } |
297 | } | |
298 | ||
299 | return res; | |
300 | } | |
301 | ||
39a25b2b VG |
302 | struct posix_acl *ovl_get_acl(struct inode *inode, int type) |
303 | { | |
09d8b586 | 304 | struct inode *realinode = ovl_inode_real(inode); |
1175b6b8 VG |
305 | const struct cred *old_cred; |
306 | struct posix_acl *acl; | |
39a25b2b | 307 | |
5201dc44 | 308 | if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode)) |
39a25b2b VG |
309 | return NULL; |
310 | ||
1175b6b8 | 311 | old_cred = ovl_override_creds(inode->i_sb); |
5201dc44 | 312 | acl = get_acl(realinode, type); |
1175b6b8 VG |
313 | revert_creds(old_cred); |
314 | ||
315 | return acl; | |
39a25b2b VG |
316 | } |
317 | ||
59be0971 | 318 | static bool ovl_open_need_copy_up(struct dentry *dentry, int flags) |
e9be9d5e | 319 | { |
59be0971 AG |
320 | if (ovl_dentry_upper(dentry) && |
321 | ovl_dentry_has_upper_alias(dentry)) | |
e9be9d5e MS |
322 | return false; |
323 | ||
59be0971 | 324 | if (special_file(d_inode(dentry)->i_mode)) |
e9be9d5e MS |
325 | return false; |
326 | ||
327 | if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) | |
328 | return false; | |
329 | ||
330 | return true; | |
331 | } | |
332 | ||
2d902671 | 333 | int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags) |
e9be9d5e | 334 | { |
2d902671 | 335 | int err = 0; |
e9be9d5e | 336 | |
59be0971 | 337 | if (ovl_open_need_copy_up(dentry, file_flags)) { |
e9be9d5e | 338 | err = ovl_want_write(dentry); |
2d902671 | 339 | if (!err) { |
9aba6521 | 340 | err = ovl_copy_up_flags(dentry, file_flags); |
2d902671 MS |
341 | ovl_drop_write(dentry); |
342 | } | |
e9be9d5e MS |
343 | } |
344 | ||
2d902671 | 345 | return err; |
e9be9d5e MS |
346 | } |
347 | ||
d719e8f2 MS |
348 | int ovl_update_time(struct inode *inode, struct timespec *ts, int flags) |
349 | { | |
350 | struct dentry *alias; | |
351 | struct path upperpath; | |
352 | ||
353 | if (!(flags & S_ATIME)) | |
354 | return 0; | |
355 | ||
356 | alias = d_find_any_alias(inode); | |
357 | if (!alias) | |
358 | return 0; | |
359 | ||
360 | ovl_path_upper(alias, &upperpath); | |
361 | if (upperpath.dentry) { | |
362 | touch_atime(&upperpath); | |
363 | inode->i_atime = d_inode(upperpath.dentry)->i_atime; | |
364 | } | |
365 | ||
366 | dput(alias); | |
367 | ||
368 | return 0; | |
369 | } | |
370 | ||
e9be9d5e MS |
371 | static const struct inode_operations ovl_file_inode_operations = { |
372 | .setattr = ovl_setattr, | |
373 | .permission = ovl_permission, | |
374 | .getattr = ovl_getattr, | |
e9be9d5e | 375 | .listxattr = ovl_listxattr, |
39a25b2b | 376 | .get_acl = ovl_get_acl, |
d719e8f2 | 377 | .update_time = ovl_update_time, |
e9be9d5e MS |
378 | }; |
379 | ||
380 | static const struct inode_operations ovl_symlink_inode_operations = { | |
381 | .setattr = ovl_setattr, | |
6b255391 | 382 | .get_link = ovl_get_link, |
e9be9d5e | 383 | .getattr = ovl_getattr, |
e9be9d5e | 384 | .listxattr = ovl_listxattr, |
d719e8f2 | 385 | .update_time = ovl_update_time, |
e9be9d5e MS |
386 | }; |
387 | ||
b1eaa950 AG |
388 | /* |
389 | * It is possible to stack overlayfs instance on top of another | |
390 | * overlayfs instance as lower layer. We need to annonate the | |
391 | * stackable i_mutex locks according to stack level of the super | |
392 | * block instance. An overlayfs instance can never be in stack | |
393 | * depth 0 (there is always a real fs below it). An overlayfs | |
394 | * inode lock will use the lockdep annotaion ovl_i_mutex_key[depth]. | |
395 | * | |
396 | * For example, here is a snip from /proc/lockdep_chains after | |
397 | * dir_iterate of nested overlayfs: | |
398 | * | |
399 | * [...] &ovl_i_mutex_dir_key[depth] (stack_depth=2) | |
400 | * [...] &ovl_i_mutex_dir_key[depth]#2 (stack_depth=1) | |
401 | * [...] &type->i_mutex_dir_key (stack_depth=0) | |
402 | */ | |
403 | #define OVL_MAX_NESTING FILESYSTEM_MAX_STACK_DEPTH | |
404 | ||
405 | static inline void ovl_lockdep_annotate_inode_mutex_key(struct inode *inode) | |
406 | { | |
407 | #ifdef CONFIG_LOCKDEP | |
408 | static struct lock_class_key ovl_i_mutex_key[OVL_MAX_NESTING]; | |
409 | static struct lock_class_key ovl_i_mutex_dir_key[OVL_MAX_NESTING]; | |
410 | ||
411 | int depth = inode->i_sb->s_stack_depth - 1; | |
412 | ||
413 | if (WARN_ON_ONCE(depth < 0 || depth >= OVL_MAX_NESTING)) | |
414 | depth = 0; | |
415 | ||
416 | if (S_ISDIR(inode->i_mode)) | |
417 | lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_dir_key[depth]); | |
418 | else | |
419 | lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_key[depth]); | |
420 | #endif | |
421 | } | |
422 | ||
ca4c8a3a | 423 | static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev) |
e9be9d5e | 424 | { |
e9be9d5e MS |
425 | inode->i_ino = get_next_ino(); |
426 | inode->i_mode = mode; | |
d719e8f2 | 427 | inode->i_flags |= S_NOCMTIME; |
2a3a2a3f MS |
428 | #ifdef CONFIG_FS_POSIX_ACL |
429 | inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE; | |
430 | #endif | |
e9be9d5e | 431 | |
b1eaa950 AG |
432 | ovl_lockdep_annotate_inode_mutex_key(inode); |
433 | ||
ca4c8a3a MS |
434 | switch (mode & S_IFMT) { |
435 | case S_IFREG: | |
436 | inode->i_op = &ovl_file_inode_operations; | |
437 | break; | |
438 | ||
e9be9d5e | 439 | case S_IFDIR: |
e9be9d5e MS |
440 | inode->i_op = &ovl_dir_inode_operations; |
441 | inode->i_fop = &ovl_dir_operations; | |
442 | break; | |
443 | ||
444 | case S_IFLNK: | |
445 | inode->i_op = &ovl_symlink_inode_operations; | |
446 | break; | |
447 | ||
51f7e52d | 448 | default: |
e9be9d5e | 449 | inode->i_op = &ovl_file_inode_operations; |
ca4c8a3a | 450 | init_special_inode(inode, mode, rdev); |
e9be9d5e | 451 | break; |
51f7e52d MS |
452 | } |
453 | } | |
e9be9d5e | 454 | |
5f8415d6 AG |
455 | /* |
456 | * With inodes index enabled, an overlay inode nlink counts the union of upper | |
457 | * hardlinks and non-covered lower hardlinks. During the lifetime of a non-pure | |
458 | * upper inode, the following nlink modifying operations can happen: | |
459 | * | |
460 | * 1. Lower hardlink copy up | |
461 | * 2. Upper hardlink created, unlinked or renamed over | |
462 | * 3. Lower hardlink whiteout or renamed over | |
463 | * | |
464 | * For the first, copy up case, the union nlink does not change, whether the | |
465 | * operation succeeds or fails, but the upper inode nlink may change. | |
466 | * Therefore, before copy up, we store the union nlink value relative to the | |
467 | * lower inode nlink in the index inode xattr trusted.overlay.nlink. | |
468 | * | |
469 | * For the second, upper hardlink case, the union nlink should be incremented | |
470 | * or decremented IFF the operation succeeds, aligned with nlink change of the | |
471 | * upper inode. Therefore, before link/unlink/rename, we store the union nlink | |
472 | * value relative to the upper inode nlink in the index inode. | |
473 | * | |
474 | * For the last, lower cover up case, we simplify things by preceding the | |
475 | * whiteout or cover up with copy up. This makes sure that there is an index | |
476 | * upper inode where the nlink xattr can be stored before the copied up upper | |
477 | * entry is unlink. | |
478 | */ | |
479 | #define OVL_NLINK_ADD_UPPER (1 << 0) | |
480 | ||
481 | /* | |
482 | * On-disk format for indexed nlink: | |
483 | * | |
484 | * nlink relative to the upper inode - "U[+-]NUM" | |
485 | * nlink relative to the lower inode - "L[+-]NUM" | |
486 | */ | |
487 | ||
488 | static int ovl_set_nlink_common(struct dentry *dentry, | |
489 | struct dentry *realdentry, const char *format) | |
490 | { | |
491 | struct inode *inode = d_inode(dentry); | |
492 | struct inode *realinode = d_inode(realdentry); | |
493 | char buf[13]; | |
494 | int len; | |
495 | ||
496 | len = snprintf(buf, sizeof(buf), format, | |
497 | (int) (inode->i_nlink - realinode->i_nlink)); | |
498 | ||
499 | return ovl_do_setxattr(ovl_dentry_upper(dentry), | |
500 | OVL_XATTR_NLINK, buf, len, 0); | |
501 | } | |
502 | ||
503 | int ovl_set_nlink_upper(struct dentry *dentry) | |
504 | { | |
505 | return ovl_set_nlink_common(dentry, ovl_dentry_upper(dentry), "U%+i"); | |
506 | } | |
507 | ||
508 | int ovl_set_nlink_lower(struct dentry *dentry) | |
509 | { | |
510 | return ovl_set_nlink_common(dentry, ovl_dentry_lower(dentry), "L%+i"); | |
511 | } | |
512 | ||
caf70cb2 AG |
513 | unsigned int ovl_get_nlink(struct dentry *lowerdentry, |
514 | struct dentry *upperdentry, | |
515 | unsigned int fallback) | |
5f8415d6 AG |
516 | { |
517 | int nlink_diff; | |
518 | int nlink; | |
519 | char buf[13]; | |
520 | int err; | |
521 | ||
522 | if (!lowerdentry || !upperdentry || d_inode(lowerdentry)->i_nlink == 1) | |
523 | return fallback; | |
524 | ||
525 | err = vfs_getxattr(upperdentry, OVL_XATTR_NLINK, &buf, sizeof(buf) - 1); | |
526 | if (err < 0) | |
527 | goto fail; | |
528 | ||
529 | buf[err] = '\0'; | |
530 | if ((buf[0] != 'L' && buf[0] != 'U') || | |
531 | (buf[1] != '+' && buf[1] != '-')) | |
532 | goto fail; | |
533 | ||
534 | err = kstrtoint(buf + 1, 10, &nlink_diff); | |
535 | if (err < 0) | |
536 | goto fail; | |
537 | ||
538 | nlink = d_inode(buf[0] == 'L' ? lowerdentry : upperdentry)->i_nlink; | |
539 | nlink += nlink_diff; | |
540 | ||
541 | if (nlink <= 0) | |
542 | goto fail; | |
543 | ||
544 | return nlink; | |
545 | ||
546 | fail: | |
547 | pr_warn_ratelimited("overlayfs: failed to get index nlink (%pd2, err=%i)\n", | |
548 | upperdentry, err); | |
549 | return fallback; | |
550 | } | |
551 | ||
ca4c8a3a | 552 | struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev) |
51f7e52d MS |
553 | { |
554 | struct inode *inode; | |
555 | ||
556 | inode = new_inode(sb); | |
557 | if (inode) | |
ca4c8a3a | 558 | ovl_fill_inode(inode, mode, rdev); |
51f7e52d MS |
559 | |
560 | return inode; | |
561 | } | |
562 | ||
563 | static int ovl_inode_test(struct inode *inode, void *data) | |
564 | { | |
25b7713a | 565 | return inode->i_private == data; |
51f7e52d MS |
566 | } |
567 | ||
568 | static int ovl_inode_set(struct inode *inode, void *data) | |
569 | { | |
25b7713a | 570 | inode->i_private = data; |
51f7e52d MS |
571 | return 0; |
572 | } | |
573 | ||
b9ac5c27 MS |
574 | static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry, |
575 | struct dentry *upperdentry) | |
576 | { | |
577 | struct inode *lowerinode = lowerdentry ? d_inode(lowerdentry) : NULL; | |
578 | ||
579 | /* Lower (origin) inode must match, even if NULL */ | |
580 | if (ovl_inode_lower(inode) != lowerinode) | |
581 | return false; | |
582 | ||
583 | /* | |
584 | * Allow non-NULL __upperdentry in inode even if upperdentry is NULL. | |
585 | * This happens when finding a lower alias for a copied up hard link. | |
586 | */ | |
587 | if (upperdentry && ovl_inode_upper(inode) != d_inode(upperdentry)) | |
588 | return false; | |
589 | ||
590 | return true; | |
591 | } | |
592 | ||
09d8b586 | 593 | struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry) |
51f7e52d | 594 | { |
09d8b586 MS |
595 | struct dentry *lowerdentry = ovl_dentry_lower(dentry); |
596 | struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL; | |
51f7e52d MS |
597 | struct inode *inode; |
598 | ||
09d8b586 MS |
599 | if (!realinode) |
600 | realinode = d_inode(lowerdentry); | |
601 | ||
b9ac5c27 MS |
602 | if (!S_ISDIR(realinode->i_mode) && |
603 | (upperdentry || (lowerdentry && ovl_indexdir(dentry->d_sb)))) { | |
604 | struct inode *key = d_inode(lowerdentry ?: upperdentry); | |
5f8415d6 | 605 | unsigned int nlink; |
b9ac5c27 MS |
606 | |
607 | inode = iget5_locked(dentry->d_sb, (unsigned long) key, | |
608 | ovl_inode_test, ovl_inode_set, key); | |
09d8b586 | 609 | if (!inode) |
b9ac5c27 | 610 | goto out_nomem; |
09d8b586 | 611 | if (!(inode->i_state & I_NEW)) { |
b9ac5c27 MS |
612 | /* |
613 | * Verify that the underlying files stored in the inode | |
614 | * match those in the dentry. | |
615 | */ | |
616 | if (!ovl_verify_inode(inode, lowerdentry, upperdentry)) { | |
617 | iput(inode); | |
618 | inode = ERR_PTR(-ESTALE); | |
619 | goto out; | |
620 | } | |
621 | ||
09d8b586 MS |
622 | dput(upperdentry); |
623 | goto out; | |
624 | } | |
e6d2ebdd | 625 | |
5f8415d6 AG |
626 | nlink = ovl_get_nlink(lowerdentry, upperdentry, |
627 | realinode->i_nlink); | |
628 | set_nlink(inode, nlink); | |
e6d2ebdd MS |
629 | } else { |
630 | inode = new_inode(dentry->d_sb); | |
631 | if (!inode) | |
b9ac5c27 | 632 | goto out_nomem; |
e9be9d5e | 633 | } |
e6d2ebdd | 634 | ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev); |
09d8b586 | 635 | ovl_inode_init(inode, upperdentry, lowerdentry); |
13c72075 MS |
636 | |
637 | if (upperdentry && ovl_is_impuredir(upperdentry)) | |
638 | ovl_set_flag(OVL_IMPURE, inode); | |
639 | ||
e6d2ebdd MS |
640 | if (inode->i_state & I_NEW) |
641 | unlock_new_inode(inode); | |
642 | out: | |
e9be9d5e | 643 | return inode; |
b9ac5c27 MS |
644 | |
645 | out_nomem: | |
646 | inode = ERR_PTR(-ENOMEM); | |
647 | goto out; | |
e9be9d5e | 648 | } |