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Commit | Line | Data |
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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 | ||
ba1e563c CR |
18 | |
19 | static dev_t ovl_get_pseudo_dev(struct dentry *dentry) | |
20 | { | |
21 | struct ovl_entry *oe = dentry->d_fsdata; | |
22 | ||
23 | return oe->lowerstack[0].layer->pseudo_dev; | |
24 | } | |
25 | ||
e9be9d5e MS |
26 | int ovl_setattr(struct dentry *dentry, struct iattr *attr) |
27 | { | |
28 | int err; | |
29 | struct dentry *upperdentry; | |
1175b6b8 | 30 | const struct cred *old_cred; |
e9be9d5e | 31 | |
cf9a6784 MS |
32 | /* |
33 | * Check for permissions before trying to copy-up. This is redundant | |
34 | * since it will be rechecked later by ->setattr() on upper dentry. But | |
35 | * without this, copy-up can be triggered by just about anybody. | |
36 | * | |
37 | * We don't initialize inode->size, which just means that | |
38 | * inode_newsize_ok() will always check against MAX_LFS_FILESIZE and not | |
39 | * check for a swapfile (which this won't be anyway). | |
40 | */ | |
31051c85 | 41 | err = setattr_prepare(dentry, attr); |
cf9a6784 MS |
42 | if (err) |
43 | return err; | |
44 | ||
e9be9d5e MS |
45 | err = ovl_want_write(dentry); |
46 | if (err) | |
47 | goto out; | |
48 | ||
acff81ec MS |
49 | err = ovl_copy_up(dentry); |
50 | if (!err) { | |
51 | upperdentry = ovl_dentry_upper(dentry); | |
52 | ||
b99c2d91 MS |
53 | if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) |
54 | attr->ia_valid &= ~ATTR_MODE; | |
55 | ||
5955102c | 56 | inode_lock(upperdentry->d_inode); |
1175b6b8 | 57 | old_cred = ovl_override_creds(dentry->d_sb); |
e9be9d5e | 58 | err = notify_change(upperdentry, attr, NULL); |
1175b6b8 | 59 | revert_creds(old_cred); |
b81de061 KK |
60 | if (!err) |
61 | ovl_copyattr(upperdentry->d_inode, dentry->d_inode); | |
5955102c | 62 | inode_unlock(upperdentry->d_inode); |
e9be9d5e MS |
63 | } |
64 | ovl_drop_write(dentry); | |
65 | out: | |
66 | return err; | |
67 | } | |
68 | ||
5b712091 MS |
69 | int ovl_getattr(const struct path *path, struct kstat *stat, |
70 | u32 request_mask, unsigned int flags) | |
e9be9d5e | 71 | { |
a528d35e | 72 | struct dentry *dentry = path->dentry; |
72b608f0 | 73 | enum ovl_path_type type; |
e9be9d5e | 74 | struct path realpath; |
1175b6b8 | 75 | const struct cred *old_cred; |
5b712091 | 76 | bool is_dir = S_ISDIR(dentry->d_inode->i_mode); |
a0c5ad30 | 77 | bool samefs = ovl_same_sb(dentry->d_sb); |
1175b6b8 | 78 | int err; |
e9be9d5e | 79 | |
72b608f0 | 80 | type = ovl_path_real(dentry, &realpath); |
1175b6b8 | 81 | old_cred = ovl_override_creds(dentry->d_sb); |
a528d35e | 82 | err = vfs_getattr(&realpath, stat, request_mask, flags); |
72b608f0 AG |
83 | if (err) |
84 | goto out; | |
85 | ||
86 | /* | |
a0c5ad30 AG |
87 | * For non-dir or same fs, we use st_ino of the copy up origin, if we |
88 | * know it. This guaranties constant st_dev/st_ino across copy up. | |
72b608f0 AG |
89 | * |
90 | * If filesystem supports NFS export ops, this also guaranties | |
91 | * persistent st_ino across mount cycle. | |
92 | */ | |
a0c5ad30 | 93 | if (!is_dir || samefs) { |
72b608f0 AG |
94 | if (OVL_TYPE_ORIGIN(type)) { |
95 | struct kstat lowerstat; | |
5b712091 | 96 | u32 lowermask = STATX_INO | (!is_dir ? STATX_NLINK : 0); |
72b608f0 AG |
97 | |
98 | ovl_path_lower(dentry, &realpath); | |
99 | err = vfs_getattr(&realpath, &lowerstat, | |
5b712091 | 100 | lowermask, flags); |
72b608f0 AG |
101 | if (err) |
102 | goto out; | |
103 | ||
72b608f0 | 104 | /* |
359f392c | 105 | * Lower hardlinks may be broken on copy up to different |
72b608f0 AG |
106 | * upper files, so we cannot use the lower origin st_ino |
107 | * for those different files, even for the same fs case. | |
359f392c AG |
108 | * With inodes index enabled, it is safe to use st_ino |
109 | * of an indexed hardlinked origin. The index validates | |
110 | * that the upper hardlink is not broken. | |
72b608f0 | 111 | */ |
359f392c | 112 | if (is_dir || lowerstat.nlink == 1 || |
a39a8c30 | 113 | ovl_test_flag(OVL_INDEX, d_inode(dentry))) { |
72b608f0 | 114 | stat->ino = lowerstat.ino; |
a0c5ad30 | 115 | stat->dev = ovl_get_pseudo_dev(dentry); |
a39a8c30 | 116 | } |
72b608f0 | 117 | } |
a0c5ad30 AG |
118 | if (samefs) { |
119 | /* | |
120 | * When all layers are on the same fs, all real inode | |
121 | * number are unique, so we use the overlay st_dev, | |
122 | * which is friendly to du -x. | |
123 | */ | |
124 | stat->dev = dentry->d_sb->s_dev; | |
125 | } else if (!OVL_TYPE_UPPER(type)) { | |
126 | /* | |
127 | * For non-samefs setup, to make sure that st_dev/st_ino | |
128 | * pair is unique across the system, we use a unique | |
129 | * anonymous st_dev for lower layer inode. | |
130 | */ | |
131 | stat->dev = ovl_get_pseudo_dev(dentry); | |
132 | } | |
133 | } else { | |
5b712091 | 134 | /* |
5b712091 MS |
135 | * Always use the overlay st_dev for directories, so 'find |
136 | * -xdev' will scan the entire overlay mount and won't cross the | |
137 | * overlay mount boundaries. | |
a0c5ad30 AG |
138 | * |
139 | * If not all layers are on the same fs the pair {real st_ino; | |
140 | * overlay st_dev} is not unique, so use the non persistent | |
141 | * overlay st_ino for directories. | |
5b712091 MS |
142 | */ |
143 | stat->dev = dentry->d_sb->s_dev; | |
144 | stat->ino = dentry->d_inode->i_ino; | |
72b608f0 | 145 | } |
5b712091 MS |
146 | |
147 | /* | |
148 | * It's probably not worth it to count subdirs to get the | |
149 | * correct link count. nlink=1 seems to pacify 'find' and | |
150 | * other utilities. | |
151 | */ | |
152 | if (is_dir && OVL_TYPE_MERGE(type)) | |
153 | stat->nlink = 1; | |
154 | ||
5f8415d6 AG |
155 | /* |
156 | * Return the overlay inode nlinks for indexed upper inodes. | |
157 | * Overlay inode nlink counts the union of the upper hardlinks | |
158 | * and non-covered lower hardlinks. It does not include the upper | |
159 | * index hardlink. | |
160 | */ | |
161 | if (!is_dir && ovl_test_flag(OVL_INDEX, d_inode(dentry))) | |
162 | stat->nlink = dentry->d_inode->i_nlink; | |
163 | ||
72b608f0 | 164 | out: |
1175b6b8 | 165 | revert_creds(old_cred); |
72b608f0 | 166 | |
1175b6b8 | 167 | return err; |
e9be9d5e MS |
168 | } |
169 | ||
170 | int ovl_permission(struct inode *inode, int mask) | |
171 | { | |
09d8b586 MS |
172 | struct inode *upperinode = ovl_inode_upper(inode); |
173 | struct inode *realinode = upperinode ?: ovl_inode_lower(inode); | |
c0ca3d70 | 174 | const struct cred *old_cred; |
e9be9d5e MS |
175 | int err; |
176 | ||
e9be9d5e | 177 | /* Careful in RCU walk mode */ |
e9be9d5e MS |
178 | if (!realinode) { |
179 | WARN_ON(!(mask & MAY_NOT_BLOCK)); | |
a999d7e1 | 180 | return -ECHILD; |
e9be9d5e MS |
181 | } |
182 | ||
c0ca3d70 VG |
183 | /* |
184 | * Check overlay inode with the creds of task and underlying inode | |
185 | * with creds of mounter | |
186 | */ | |
187 | err = generic_permission(inode, mask); | |
188 | if (err) | |
189 | return err; | |
190 | ||
191 | old_cred = ovl_override_creds(inode->i_sb); | |
09d8b586 MS |
192 | if (!upperinode && |
193 | !special_file(realinode->i_mode) && mask & MAY_WRITE) { | |
754f8cb7 | 194 | mask &= ~(MAY_WRITE | MAY_APPEND); |
500cac3c VG |
195 | /* Make sure mounter can read file for copy up later */ |
196 | mask |= MAY_READ; | |
197 | } | |
9c630ebe | 198 | err = inode_permission(realinode, mask); |
c0ca3d70 VG |
199 | revert_creds(old_cred); |
200 | ||
201 | return err; | |
e9be9d5e MS |
202 | } |
203 | ||
6b255391 | 204 | static const char *ovl_get_link(struct dentry *dentry, |
fceef393 AV |
205 | struct inode *inode, |
206 | struct delayed_call *done) | |
e9be9d5e | 207 | { |
1175b6b8 VG |
208 | const struct cred *old_cred; |
209 | const char *p; | |
e9be9d5e | 210 | |
6b255391 AV |
211 | if (!dentry) |
212 | return ERR_PTR(-ECHILD); | |
213 | ||
1175b6b8 | 214 | old_cred = ovl_override_creds(dentry->d_sb); |
7764235b | 215 | p = vfs_get_link(ovl_dentry_real(dentry), done); |
1175b6b8 VG |
216 | revert_creds(old_cred); |
217 | return p; | |
e9be9d5e MS |
218 | } |
219 | ||
0956254a | 220 | bool ovl_is_private_xattr(const char *name) |
e9be9d5e | 221 | { |
fe2b7595 AG |
222 | return strncmp(name, OVL_XATTR_PREFIX, |
223 | sizeof(OVL_XATTR_PREFIX) - 1) == 0; | |
e9be9d5e MS |
224 | } |
225 | ||
1d88f183 MS |
226 | int ovl_xattr_set(struct dentry *dentry, struct inode *inode, const char *name, |
227 | const void *value, size_t size, int flags) | |
e9be9d5e MS |
228 | { |
229 | int err; | |
1d88f183 MS |
230 | struct dentry *upperdentry = ovl_i_dentry_upper(inode); |
231 | struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry); | |
1175b6b8 | 232 | const struct cred *old_cred; |
e9be9d5e MS |
233 | |
234 | err = ovl_want_write(dentry); | |
235 | if (err) | |
236 | goto out; | |
237 | ||
1d88f183 MS |
238 | if (!value && !upperdentry) { |
239 | err = vfs_getxattr(realdentry, name, NULL, 0); | |
0e585ccc AG |
240 | if (err < 0) |
241 | goto out_drop_write; | |
242 | } | |
243 | ||
1d88f183 MS |
244 | if (!upperdentry) { |
245 | err = ovl_copy_up(dentry); | |
246 | if (err) | |
247 | goto out_drop_write; | |
e9be9d5e | 248 | |
1d88f183 MS |
249 | realdentry = ovl_dentry_upper(dentry); |
250 | } | |
0e585ccc | 251 | |
1175b6b8 | 252 | old_cred = ovl_override_creds(dentry->d_sb); |
0e585ccc | 253 | if (value) |
1d88f183 | 254 | err = vfs_setxattr(realdentry, name, value, size, flags); |
0e585ccc AG |
255 | else { |
256 | WARN_ON(flags != XATTR_REPLACE); | |
1d88f183 | 257 | err = vfs_removexattr(realdentry, name); |
0e585ccc | 258 | } |
1175b6b8 | 259 | revert_creds(old_cred); |
e9be9d5e MS |
260 | |
261 | out_drop_write: | |
262 | ovl_drop_write(dentry); | |
263 | out: | |
264 | return err; | |
265 | } | |
266 | ||
1d88f183 | 267 | int ovl_xattr_get(struct dentry *dentry, struct inode *inode, const char *name, |
0eb45fc3 | 268 | void *value, size_t size) |
e9be9d5e | 269 | { |
1175b6b8 VG |
270 | ssize_t res; |
271 | const struct cred *old_cred; | |
1d88f183 MS |
272 | struct dentry *realdentry = |
273 | ovl_i_dentry_upper(inode) ?: ovl_dentry_lower(dentry); | |
52148463 | 274 | |
1175b6b8 VG |
275 | old_cred = ovl_override_creds(dentry->d_sb); |
276 | res = vfs_getxattr(realdentry, name, value, size); | |
277 | revert_creds(old_cred); | |
278 | return res; | |
e9be9d5e MS |
279 | } |
280 | ||
a082c6f6 MS |
281 | static bool ovl_can_list(const char *s) |
282 | { | |
283 | /* List all non-trusted xatts */ | |
284 | if (strncmp(s, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN) != 0) | |
285 | return true; | |
286 | ||
287 | /* Never list trusted.overlay, list other trusted for superuser only */ | |
288 | return !ovl_is_private_xattr(s) && capable(CAP_SYS_ADMIN); | |
289 | } | |
290 | ||
e9be9d5e MS |
291 | ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) |
292 | { | |
b581755b | 293 | struct dentry *realdentry = ovl_dentry_real(dentry); |
e9be9d5e | 294 | ssize_t res; |
7cb35119 MS |
295 | size_t len; |
296 | char *s; | |
1175b6b8 | 297 | const struct cred *old_cred; |
e9be9d5e | 298 | |
1175b6b8 | 299 | old_cred = ovl_override_creds(dentry->d_sb); |
b581755b | 300 | res = vfs_listxattr(realdentry, list, size); |
1175b6b8 | 301 | revert_creds(old_cred); |
e9be9d5e MS |
302 | if (res <= 0 || size == 0) |
303 | return res; | |
304 | ||
e9be9d5e | 305 | /* filter out private xattrs */ |
7cb35119 MS |
306 | for (s = list, len = res; len;) { |
307 | size_t slen = strnlen(s, len) + 1; | |
e9be9d5e | 308 | |
7cb35119 MS |
309 | /* underlying fs providing us with an broken xattr list? */ |
310 | if (WARN_ON(slen > len)) | |
311 | return -EIO; | |
e9be9d5e | 312 | |
7cb35119 | 313 | len -= slen; |
a082c6f6 | 314 | if (!ovl_can_list(s)) { |
e9be9d5e | 315 | res -= slen; |
7cb35119 | 316 | memmove(s, s + slen, len); |
e9be9d5e | 317 | } else { |
7cb35119 | 318 | s += slen; |
e9be9d5e MS |
319 | } |
320 | } | |
321 | ||
322 | return res; | |
323 | } | |
324 | ||
39a25b2b VG |
325 | struct posix_acl *ovl_get_acl(struct inode *inode, int type) |
326 | { | |
09d8b586 | 327 | struct inode *realinode = ovl_inode_real(inode); |
1175b6b8 VG |
328 | const struct cred *old_cred; |
329 | struct posix_acl *acl; | |
39a25b2b | 330 | |
5201dc44 | 331 | if (!IS_ENABLED(CONFIG_FS_POSIX_ACL) || !IS_POSIXACL(realinode)) |
39a25b2b VG |
332 | return NULL; |
333 | ||
1175b6b8 | 334 | old_cred = ovl_override_creds(inode->i_sb); |
5201dc44 | 335 | acl = get_acl(realinode, type); |
1175b6b8 VG |
336 | revert_creds(old_cred); |
337 | ||
338 | return acl; | |
39a25b2b VG |
339 | } |
340 | ||
59be0971 | 341 | static bool ovl_open_need_copy_up(struct dentry *dentry, int flags) |
e9be9d5e | 342 | { |
59be0971 AG |
343 | if (ovl_dentry_upper(dentry) && |
344 | ovl_dentry_has_upper_alias(dentry)) | |
e9be9d5e MS |
345 | return false; |
346 | ||
59be0971 | 347 | if (special_file(d_inode(dentry)->i_mode)) |
e9be9d5e MS |
348 | return false; |
349 | ||
350 | if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC)) | |
351 | return false; | |
352 | ||
353 | return true; | |
354 | } | |
355 | ||
2d902671 | 356 | int ovl_open_maybe_copy_up(struct dentry *dentry, unsigned int file_flags) |
e9be9d5e | 357 | { |
2d902671 | 358 | int err = 0; |
e9be9d5e | 359 | |
59be0971 | 360 | if (ovl_open_need_copy_up(dentry, file_flags)) { |
e9be9d5e | 361 | err = ovl_want_write(dentry); |
2d902671 | 362 | if (!err) { |
9aba6521 | 363 | err = ovl_copy_up_flags(dentry, file_flags); |
2d902671 MS |
364 | ovl_drop_write(dentry); |
365 | } | |
e9be9d5e MS |
366 | } |
367 | ||
2d902671 | 368 | return err; |
e9be9d5e MS |
369 | } |
370 | ||
d719e8f2 MS |
371 | int ovl_update_time(struct inode *inode, struct timespec *ts, int flags) |
372 | { | |
373 | struct dentry *alias; | |
374 | struct path upperpath; | |
375 | ||
376 | if (!(flags & S_ATIME)) | |
377 | return 0; | |
378 | ||
379 | alias = d_find_any_alias(inode); | |
380 | if (!alias) | |
381 | return 0; | |
382 | ||
383 | ovl_path_upper(alias, &upperpath); | |
384 | if (upperpath.dentry) { | |
385 | touch_atime(&upperpath); | |
386 | inode->i_atime = d_inode(upperpath.dentry)->i_atime; | |
387 | } | |
388 | ||
389 | dput(alias); | |
390 | ||
391 | return 0; | |
392 | } | |
393 | ||
e9be9d5e MS |
394 | static const struct inode_operations ovl_file_inode_operations = { |
395 | .setattr = ovl_setattr, | |
396 | .permission = ovl_permission, | |
397 | .getattr = ovl_getattr, | |
e9be9d5e | 398 | .listxattr = ovl_listxattr, |
39a25b2b | 399 | .get_acl = ovl_get_acl, |
d719e8f2 | 400 | .update_time = ovl_update_time, |
e9be9d5e MS |
401 | }; |
402 | ||
403 | static const struct inode_operations ovl_symlink_inode_operations = { | |
404 | .setattr = ovl_setattr, | |
6b255391 | 405 | .get_link = ovl_get_link, |
e9be9d5e | 406 | .getattr = ovl_getattr, |
e9be9d5e | 407 | .listxattr = ovl_listxattr, |
d719e8f2 | 408 | .update_time = ovl_update_time, |
e9be9d5e MS |
409 | }; |
410 | ||
b1eaa950 AG |
411 | /* |
412 | * It is possible to stack overlayfs instance on top of another | |
413 | * overlayfs instance as lower layer. We need to annonate the | |
414 | * stackable i_mutex locks according to stack level of the super | |
415 | * block instance. An overlayfs instance can never be in stack | |
416 | * depth 0 (there is always a real fs below it). An overlayfs | |
417 | * inode lock will use the lockdep annotaion ovl_i_mutex_key[depth]. | |
418 | * | |
419 | * For example, here is a snip from /proc/lockdep_chains after | |
420 | * dir_iterate of nested overlayfs: | |
421 | * | |
422 | * [...] &ovl_i_mutex_dir_key[depth] (stack_depth=2) | |
423 | * [...] &ovl_i_mutex_dir_key[depth]#2 (stack_depth=1) | |
424 | * [...] &type->i_mutex_dir_key (stack_depth=0) | |
425 | */ | |
426 | #define OVL_MAX_NESTING FILESYSTEM_MAX_STACK_DEPTH | |
427 | ||
428 | static inline void ovl_lockdep_annotate_inode_mutex_key(struct inode *inode) | |
429 | { | |
430 | #ifdef CONFIG_LOCKDEP | |
431 | static struct lock_class_key ovl_i_mutex_key[OVL_MAX_NESTING]; | |
432 | static struct lock_class_key ovl_i_mutex_dir_key[OVL_MAX_NESTING]; | |
4eae06de | 433 | static struct lock_class_key ovl_i_lock_key[OVL_MAX_NESTING]; |
b1eaa950 AG |
434 | |
435 | int depth = inode->i_sb->s_stack_depth - 1; | |
436 | ||
437 | if (WARN_ON_ONCE(depth < 0 || depth >= OVL_MAX_NESTING)) | |
438 | depth = 0; | |
439 | ||
440 | if (S_ISDIR(inode->i_mode)) | |
441 | lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_dir_key[depth]); | |
442 | else | |
443 | lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_key[depth]); | |
4eae06de AG |
444 | |
445 | lockdep_set_class(&OVL_I(inode)->lock, &ovl_i_lock_key[depth]); | |
b1eaa950 AG |
446 | #endif |
447 | } | |
448 | ||
ca4c8a3a | 449 | static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev) |
e9be9d5e | 450 | { |
e9be9d5e MS |
451 | inode->i_ino = get_next_ino(); |
452 | inode->i_mode = mode; | |
d719e8f2 | 453 | inode->i_flags |= S_NOCMTIME; |
2a3a2a3f MS |
454 | #ifdef CONFIG_FS_POSIX_ACL |
455 | inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE; | |
456 | #endif | |
e9be9d5e | 457 | |
b1eaa950 AG |
458 | ovl_lockdep_annotate_inode_mutex_key(inode); |
459 | ||
ca4c8a3a MS |
460 | switch (mode & S_IFMT) { |
461 | case S_IFREG: | |
462 | inode->i_op = &ovl_file_inode_operations; | |
463 | break; | |
464 | ||
e9be9d5e | 465 | case S_IFDIR: |
e9be9d5e MS |
466 | inode->i_op = &ovl_dir_inode_operations; |
467 | inode->i_fop = &ovl_dir_operations; | |
468 | break; | |
469 | ||
470 | case S_IFLNK: | |
471 | inode->i_op = &ovl_symlink_inode_operations; | |
472 | break; | |
473 | ||
51f7e52d | 474 | default: |
e9be9d5e | 475 | inode->i_op = &ovl_file_inode_operations; |
ca4c8a3a | 476 | init_special_inode(inode, mode, rdev); |
e9be9d5e | 477 | break; |
51f7e52d MS |
478 | } |
479 | } | |
e9be9d5e | 480 | |
5f8415d6 AG |
481 | /* |
482 | * With inodes index enabled, an overlay inode nlink counts the union of upper | |
483 | * hardlinks and non-covered lower hardlinks. During the lifetime of a non-pure | |
484 | * upper inode, the following nlink modifying operations can happen: | |
485 | * | |
486 | * 1. Lower hardlink copy up | |
487 | * 2. Upper hardlink created, unlinked or renamed over | |
488 | * 3. Lower hardlink whiteout or renamed over | |
489 | * | |
490 | * For the first, copy up case, the union nlink does not change, whether the | |
491 | * operation succeeds or fails, but the upper inode nlink may change. | |
492 | * Therefore, before copy up, we store the union nlink value relative to the | |
493 | * lower inode nlink in the index inode xattr trusted.overlay.nlink. | |
494 | * | |
495 | * For the second, upper hardlink case, the union nlink should be incremented | |
496 | * or decremented IFF the operation succeeds, aligned with nlink change of the | |
497 | * upper inode. Therefore, before link/unlink/rename, we store the union nlink | |
498 | * value relative to the upper inode nlink in the index inode. | |
499 | * | |
500 | * For the last, lower cover up case, we simplify things by preceding the | |
501 | * whiteout or cover up with copy up. This makes sure that there is an index | |
502 | * upper inode where the nlink xattr can be stored before the copied up upper | |
503 | * entry is unlink. | |
504 | */ | |
505 | #define OVL_NLINK_ADD_UPPER (1 << 0) | |
506 | ||
507 | /* | |
508 | * On-disk format for indexed nlink: | |
509 | * | |
510 | * nlink relative to the upper inode - "U[+-]NUM" | |
511 | * nlink relative to the lower inode - "L[+-]NUM" | |
512 | */ | |
513 | ||
514 | static int ovl_set_nlink_common(struct dentry *dentry, | |
515 | struct dentry *realdentry, const char *format) | |
516 | { | |
517 | struct inode *inode = d_inode(dentry); | |
518 | struct inode *realinode = d_inode(realdentry); | |
519 | char buf[13]; | |
520 | int len; | |
521 | ||
522 | len = snprintf(buf, sizeof(buf), format, | |
523 | (int) (inode->i_nlink - realinode->i_nlink)); | |
524 | ||
6787341a MS |
525 | if (WARN_ON(len >= sizeof(buf))) |
526 | return -EIO; | |
527 | ||
5f8415d6 AG |
528 | return ovl_do_setxattr(ovl_dentry_upper(dentry), |
529 | OVL_XATTR_NLINK, buf, len, 0); | |
530 | } | |
531 | ||
532 | int ovl_set_nlink_upper(struct dentry *dentry) | |
533 | { | |
534 | return ovl_set_nlink_common(dentry, ovl_dentry_upper(dentry), "U%+i"); | |
535 | } | |
536 | ||
537 | int ovl_set_nlink_lower(struct dentry *dentry) | |
538 | { | |
539 | return ovl_set_nlink_common(dentry, ovl_dentry_lower(dentry), "L%+i"); | |
540 | } | |
541 | ||
caf70cb2 AG |
542 | unsigned int ovl_get_nlink(struct dentry *lowerdentry, |
543 | struct dentry *upperdentry, | |
544 | unsigned int fallback) | |
5f8415d6 AG |
545 | { |
546 | int nlink_diff; | |
547 | int nlink; | |
548 | char buf[13]; | |
549 | int err; | |
550 | ||
551 | if (!lowerdentry || !upperdentry || d_inode(lowerdentry)->i_nlink == 1) | |
552 | return fallback; | |
553 | ||
554 | err = vfs_getxattr(upperdentry, OVL_XATTR_NLINK, &buf, sizeof(buf) - 1); | |
555 | if (err < 0) | |
556 | goto fail; | |
557 | ||
558 | buf[err] = '\0'; | |
559 | if ((buf[0] != 'L' && buf[0] != 'U') || | |
560 | (buf[1] != '+' && buf[1] != '-')) | |
561 | goto fail; | |
562 | ||
563 | err = kstrtoint(buf + 1, 10, &nlink_diff); | |
564 | if (err < 0) | |
565 | goto fail; | |
566 | ||
567 | nlink = d_inode(buf[0] == 'L' ? lowerdentry : upperdentry)->i_nlink; | |
568 | nlink += nlink_diff; | |
569 | ||
570 | if (nlink <= 0) | |
571 | goto fail; | |
572 | ||
573 | return nlink; | |
574 | ||
575 | fail: | |
576 | pr_warn_ratelimited("overlayfs: failed to get index nlink (%pd2, err=%i)\n", | |
577 | upperdentry, err); | |
578 | return fallback; | |
579 | } | |
580 | ||
ca4c8a3a | 581 | struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev) |
51f7e52d MS |
582 | { |
583 | struct inode *inode; | |
584 | ||
585 | inode = new_inode(sb); | |
586 | if (inode) | |
ca4c8a3a | 587 | ovl_fill_inode(inode, mode, rdev); |
51f7e52d MS |
588 | |
589 | return inode; | |
590 | } | |
591 | ||
592 | static int ovl_inode_test(struct inode *inode, void *data) | |
593 | { | |
25b7713a | 594 | return inode->i_private == data; |
51f7e52d MS |
595 | } |
596 | ||
597 | static int ovl_inode_set(struct inode *inode, void *data) | |
598 | { | |
25b7713a | 599 | inode->i_private = data; |
51f7e52d MS |
600 | return 0; |
601 | } | |
602 | ||
b9ac5c27 MS |
603 | static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry, |
604 | struct dentry *upperdentry) | |
605 | { | |
d2c9584e AG |
606 | if (S_ISDIR(inode->i_mode)) { |
607 | /* Real lower dir moved to upper layer under us? */ | |
608 | if (!lowerdentry && ovl_inode_lower(inode)) | |
609 | return false; | |
610 | ||
611 | /* Lookup of an uncovered redirect origin? */ | |
612 | if (!upperdentry && ovl_inode_upper(inode)) | |
613 | return false; | |
614 | } | |
615 | ||
939ae4ef AG |
616 | /* |
617 | * Allow non-NULL lower inode in ovl_inode even if lowerdentry is NULL. | |
618 | * This happens when finding a copied up overlay inode for a renamed | |
619 | * or hardlinked overlay dentry and lower dentry cannot be followed | |
620 | * by origin because lower fs does not support file handles. | |
621 | */ | |
622 | if (lowerdentry && ovl_inode_lower(inode) != d_inode(lowerdentry)) | |
b9ac5c27 MS |
623 | return false; |
624 | ||
625 | /* | |
626 | * Allow non-NULL __upperdentry in inode even if upperdentry is NULL. | |
627 | * This happens when finding a lower alias for a copied up hard link. | |
628 | */ | |
629 | if (upperdentry && ovl_inode_upper(inode) != d_inode(upperdentry)) | |
630 | return false; | |
631 | ||
632 | return true; | |
633 | } | |
634 | ||
6eaf0111 AG |
635 | struct inode *ovl_get_inode(struct dentry *dentry, struct dentry *upperdentry, |
636 | struct dentry *index) | |
51f7e52d | 637 | { |
09d8b586 MS |
638 | struct dentry *lowerdentry = ovl_dentry_lower(dentry); |
639 | struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL; | |
51f7e52d | 640 | struct inode *inode; |
6eaf0111 AG |
641 | /* Already indexed or could be indexed on copy up? */ |
642 | bool indexed = (index || (ovl_indexdir(dentry->d_sb) && !upperdentry)); | |
d2c9584e AG |
643 | struct dentry *origin = indexed ? lowerdentry : NULL; |
644 | bool is_dir; | |
6eaf0111 AG |
645 | |
646 | if (WARN_ON(upperdentry && indexed && !lowerdentry)) | |
647 | return ERR_PTR(-EIO); | |
51f7e52d | 648 | |
09d8b586 MS |
649 | if (!realinode) |
650 | realinode = d_inode(lowerdentry); | |
651 | ||
6eaf0111 | 652 | /* |
d2c9584e AG |
653 | * Copy up origin (lower) may exist for non-indexed non-dir upper, but |
654 | * we must not use lower as hash key in that case. | |
655 | * Hash non-dir that is or could be indexed by origin inode. | |
656 | * Hash dir that is or could be merged by origin inode. | |
657 | * Hash pure upper and non-indexed non-dir by upper inode. | |
6eaf0111 | 658 | */ |
d2c9584e AG |
659 | is_dir = S_ISDIR(realinode->i_mode); |
660 | if (is_dir) | |
661 | origin = lowerdentry; | |
662 | ||
663 | if (upperdentry || origin) { | |
664 | struct inode *key = d_inode(origin ?: upperdentry); | |
665 | unsigned int nlink = is_dir ? 1 : realinode->i_nlink; | |
b9ac5c27 MS |
666 | |
667 | inode = iget5_locked(dentry->d_sb, (unsigned long) key, | |
668 | ovl_inode_test, ovl_inode_set, key); | |
09d8b586 | 669 | if (!inode) |
b9ac5c27 | 670 | goto out_nomem; |
09d8b586 | 671 | if (!(inode->i_state & I_NEW)) { |
b9ac5c27 MS |
672 | /* |
673 | * Verify that the underlying files stored in the inode | |
674 | * match those in the dentry. | |
675 | */ | |
676 | if (!ovl_verify_inode(inode, lowerdentry, upperdentry)) { | |
677 | iput(inode); | |
678 | inode = ERR_PTR(-ESTALE); | |
679 | goto out; | |
680 | } | |
681 | ||
09d8b586 MS |
682 | dput(upperdentry); |
683 | goto out; | |
684 | } | |
e6d2ebdd | 685 | |
d2c9584e AG |
686 | /* Recalculate nlink for non-dir due to indexing */ |
687 | if (!is_dir) | |
688 | nlink = ovl_get_nlink(lowerdentry, upperdentry, nlink); | |
5f8415d6 | 689 | set_nlink(inode, nlink); |
e6d2ebdd MS |
690 | } else { |
691 | inode = new_inode(dentry->d_sb); | |
692 | if (!inode) | |
b9ac5c27 | 693 | goto out_nomem; |
e9be9d5e | 694 | } |
e6d2ebdd | 695 | ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev); |
09d8b586 | 696 | ovl_inode_init(inode, upperdentry, lowerdentry); |
13c72075 MS |
697 | |
698 | if (upperdentry && ovl_is_impuredir(upperdentry)) | |
699 | ovl_set_flag(OVL_IMPURE, inode); | |
700 | ||
b79e05aa | 701 | /* Check for non-merge dir that may have whiteouts */ |
d2c9584e | 702 | if (is_dir) { |
b79e05aa AG |
703 | struct ovl_entry *oe = dentry->d_fsdata; |
704 | ||
705 | if (((upperdentry && lowerdentry) || oe->numlower > 1) || | |
706 | ovl_check_origin_xattr(upperdentry ?: lowerdentry)) { | |
707 | ovl_set_flag(OVL_WHITEOUTS, inode); | |
708 | } | |
709 | } | |
710 | ||
e6d2ebdd MS |
711 | if (inode->i_state & I_NEW) |
712 | unlock_new_inode(inode); | |
713 | out: | |
e9be9d5e | 714 | return inode; |
b9ac5c27 MS |
715 | |
716 | out_nomem: | |
717 | inode = ERR_PTR(-ENOMEM); | |
718 | goto out; | |
e9be9d5e | 719 | } |