Commit | Line | Data |
---|---|---|
bbb1e54d MS |
1 | /* |
2 | * Copyright (C) 2011 Novell Inc. | |
3 | * Copyright (C) 2016 Red Hat, 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/mount.h> | |
12 | #include <linux/slab.h> | |
5b825c3a | 13 | #include <linux/cred.h> |
bbb1e54d | 14 | #include <linux/xattr.h> |
02bcd157 AG |
15 | #include <linux/exportfs.h> |
16 | #include <linux/uuid.h> | |
caf70cb2 AG |
17 | #include <linux/namei.h> |
18 | #include <linux/ratelimit.h> | |
bbb1e54d MS |
19 | #include "overlayfs.h" |
20 | #include "ovl_entry.h" | |
21 | ||
22 | int ovl_want_write(struct dentry *dentry) | |
23 | { | |
24 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
25 | return mnt_want_write(ofs->upper_mnt); | |
26 | } | |
27 | ||
28 | void ovl_drop_write(struct dentry *dentry) | |
29 | { | |
30 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
31 | mnt_drop_write(ofs->upper_mnt); | |
32 | } | |
33 | ||
34 | struct dentry *ovl_workdir(struct dentry *dentry) | |
35 | { | |
36 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
37 | return ofs->workdir; | |
38 | } | |
39 | ||
40 | const struct cred *ovl_override_creds(struct super_block *sb) | |
41 | { | |
42 | struct ovl_fs *ofs = sb->s_fs_info; | |
43 | ||
44 | return override_creds(ofs->creator_cred); | |
45 | } | |
46 | ||
7bcd74b9 AG |
47 | struct super_block *ovl_same_sb(struct super_block *sb) |
48 | { | |
49 | struct ovl_fs *ofs = sb->s_fs_info; | |
50 | ||
51 | return ofs->same_sb; | |
52 | } | |
53 | ||
02bcd157 AG |
54 | bool ovl_can_decode_fh(struct super_block *sb) |
55 | { | |
56 | return (sb->s_export_op && sb->s_export_op->fh_to_dentry && | |
57 | !uuid_is_null(&sb->s_uuid)); | |
58 | } | |
59 | ||
60 | struct dentry *ovl_indexdir(struct super_block *sb) | |
61 | { | |
62 | struct ovl_fs *ofs = sb->s_fs_info; | |
63 | ||
64 | return ofs->indexdir; | |
65 | } | |
66 | ||
bbb1e54d MS |
67 | struct ovl_entry *ovl_alloc_entry(unsigned int numlower) |
68 | { | |
69 | size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); | |
70 | struct ovl_entry *oe = kzalloc(size, GFP_KERNEL); | |
71 | ||
72 | if (oe) | |
73 | oe->numlower = numlower; | |
74 | ||
75 | return oe; | |
76 | } | |
77 | ||
78 | bool ovl_dentry_remote(struct dentry *dentry) | |
79 | { | |
80 | return dentry->d_flags & | |
81 | (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | | |
82 | DCACHE_OP_REAL); | |
83 | } | |
84 | ||
85 | bool ovl_dentry_weird(struct dentry *dentry) | |
86 | { | |
87 | return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT | | |
88 | DCACHE_MANAGE_TRANSIT | | |
89 | DCACHE_OP_HASH | | |
90 | DCACHE_OP_COMPARE); | |
91 | } | |
92 | ||
93 | enum ovl_path_type ovl_path_type(struct dentry *dentry) | |
94 | { | |
95 | struct ovl_entry *oe = dentry->d_fsdata; | |
96 | enum ovl_path_type type = 0; | |
97 | ||
09d8b586 | 98 | if (ovl_dentry_upper(dentry)) { |
bbb1e54d MS |
99 | type = __OVL_PATH_UPPER; |
100 | ||
101 | /* | |
59548503 | 102 | * Non-dir dentry can hold lower dentry of its copy up origin. |
bbb1e54d | 103 | */ |
59548503 AG |
104 | if (oe->numlower) { |
105 | type |= __OVL_PATH_ORIGIN; | |
106 | if (d_is_dir(dentry)) | |
107 | type |= __OVL_PATH_MERGE; | |
108 | } | |
bbb1e54d MS |
109 | } else { |
110 | if (oe->numlower > 1) | |
111 | type |= __OVL_PATH_MERGE; | |
112 | } | |
113 | return type; | |
114 | } | |
115 | ||
116 | void ovl_path_upper(struct dentry *dentry, struct path *path) | |
117 | { | |
118 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
bbb1e54d MS |
119 | |
120 | path->mnt = ofs->upper_mnt; | |
09d8b586 | 121 | path->dentry = ovl_dentry_upper(dentry); |
bbb1e54d MS |
122 | } |
123 | ||
124 | void ovl_path_lower(struct dentry *dentry, struct path *path) | |
125 | { | |
126 | struct ovl_entry *oe = dentry->d_fsdata; | |
127 | ||
33006cdf | 128 | *path = oe->numlower ? oe->lowerstack[0] : (struct path) { }; |
bbb1e54d MS |
129 | } |
130 | ||
131 | enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) | |
132 | { | |
133 | enum ovl_path_type type = ovl_path_type(dentry); | |
134 | ||
135 | if (!OVL_TYPE_UPPER(type)) | |
136 | ovl_path_lower(dentry, path); | |
137 | else | |
138 | ovl_path_upper(dentry, path); | |
139 | ||
140 | return type; | |
141 | } | |
142 | ||
143 | struct dentry *ovl_dentry_upper(struct dentry *dentry) | |
144 | { | |
09d8b586 | 145 | return ovl_upperdentry_dereference(OVL_I(d_inode(dentry))); |
bbb1e54d MS |
146 | } |
147 | ||
148 | struct dentry *ovl_dentry_lower(struct dentry *dentry) | |
149 | { | |
150 | struct ovl_entry *oe = dentry->d_fsdata; | |
151 | ||
09d8b586 | 152 | return oe->numlower ? oe->lowerstack[0].dentry : NULL; |
bbb1e54d MS |
153 | } |
154 | ||
155 | struct dentry *ovl_dentry_real(struct dentry *dentry) | |
156 | { | |
09d8b586 | 157 | return ovl_dentry_upper(dentry) ?: ovl_dentry_lower(dentry); |
bbb1e54d MS |
158 | } |
159 | ||
1d88f183 MS |
160 | struct dentry *ovl_i_dentry_upper(struct inode *inode) |
161 | { | |
162 | return ovl_upperdentry_dereference(OVL_I(inode)); | |
163 | } | |
164 | ||
09d8b586 | 165 | struct inode *ovl_inode_upper(struct inode *inode) |
25b7713a | 166 | { |
1d88f183 | 167 | struct dentry *upperdentry = ovl_i_dentry_upper(inode); |
25b7713a | 168 | |
09d8b586 MS |
169 | return upperdentry ? d_inode(upperdentry) : NULL; |
170 | } | |
25b7713a | 171 | |
09d8b586 MS |
172 | struct inode *ovl_inode_lower(struct inode *inode) |
173 | { | |
174 | return OVL_I(inode)->lower; | |
175 | } | |
25b7713a | 176 | |
09d8b586 MS |
177 | struct inode *ovl_inode_real(struct inode *inode) |
178 | { | |
179 | return ovl_inode_upper(inode) ?: ovl_inode_lower(inode); | |
25b7713a MS |
180 | } |
181 | ||
09d8b586 | 182 | |
bbb1e54d MS |
183 | struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) |
184 | { | |
04a01ac7 | 185 | return OVL_I(d_inode(dentry))->cache; |
bbb1e54d MS |
186 | } |
187 | ||
188 | void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache) | |
189 | { | |
04a01ac7 | 190 | OVL_I(d_inode(dentry))->cache = cache; |
bbb1e54d MS |
191 | } |
192 | ||
193 | bool ovl_dentry_is_opaque(struct dentry *dentry) | |
194 | { | |
195 | struct ovl_entry *oe = dentry->d_fsdata; | |
196 | return oe->opaque; | |
197 | } | |
198 | ||
199 | bool ovl_dentry_is_whiteout(struct dentry *dentry) | |
200 | { | |
201 | return !dentry->d_inode && ovl_dentry_is_opaque(dentry); | |
202 | } | |
203 | ||
5cf5b477 | 204 | void ovl_dentry_set_opaque(struct dentry *dentry) |
bbb1e54d MS |
205 | { |
206 | struct ovl_entry *oe = dentry->d_fsdata; | |
5cf5b477 MS |
207 | |
208 | oe->opaque = true; | |
bbb1e54d MS |
209 | } |
210 | ||
55acc661 MS |
211 | /* |
212 | * For hard links it's possible for ovl_dentry_upper() to return positive, while | |
213 | * there's no actual upper alias for the inode. Copy up code needs to know | |
214 | * about the existence of the upper alias, so it can't use ovl_dentry_upper(). | |
215 | */ | |
216 | bool ovl_dentry_has_upper_alias(struct dentry *dentry) | |
217 | { | |
218 | struct ovl_entry *oe = dentry->d_fsdata; | |
219 | ||
220 | return oe->has_upper; | |
221 | } | |
222 | ||
223 | void ovl_dentry_set_upper_alias(struct dentry *dentry) | |
224 | { | |
225 | struct ovl_entry *oe = dentry->d_fsdata; | |
226 | ||
227 | oe->has_upper = true; | |
228 | } | |
229 | ||
a6c60655 MS |
230 | bool ovl_redirect_dir(struct super_block *sb) |
231 | { | |
232 | struct ovl_fs *ofs = sb->s_fs_info; | |
233 | ||
21a22878 | 234 | return ofs->config.redirect_dir && !ofs->noxattr; |
a6c60655 MS |
235 | } |
236 | ||
237 | const char *ovl_dentry_get_redirect(struct dentry *dentry) | |
238 | { | |
cf31c463 | 239 | return OVL_I(d_inode(dentry))->redirect; |
a6c60655 MS |
240 | } |
241 | ||
242 | void ovl_dentry_set_redirect(struct dentry *dentry, const char *redirect) | |
243 | { | |
cf31c463 | 244 | struct ovl_inode *oi = OVL_I(d_inode(dentry)); |
a6c60655 | 245 | |
cf31c463 MS |
246 | kfree(oi->redirect); |
247 | oi->redirect = redirect; | |
a6c60655 MS |
248 | } |
249 | ||
09d8b586 MS |
250 | void ovl_inode_init(struct inode *inode, struct dentry *upperdentry, |
251 | struct dentry *lowerdentry) | |
bbb1e54d | 252 | { |
09d8b586 MS |
253 | if (upperdentry) |
254 | OVL_I(inode)->__upperdentry = upperdentry; | |
255 | if (lowerdentry) | |
256 | OVL_I(inode)->lower = d_inode(lowerdentry); | |
bbb1e54d | 257 | |
09d8b586 | 258 | ovl_copyattr(d_inode(upperdentry ?: lowerdentry), inode); |
bbb1e54d MS |
259 | } |
260 | ||
09d8b586 | 261 | void ovl_inode_update(struct inode *inode, struct dentry *upperdentry) |
bbb1e54d | 262 | { |
09d8b586 | 263 | struct inode *upperinode = d_inode(upperdentry); |
e6d2ebdd | 264 | |
09d8b586 MS |
265 | WARN_ON(OVL_I(inode)->__upperdentry); |
266 | ||
25b7713a | 267 | /* |
09d8b586 | 268 | * Make sure upperdentry is consistent before making it visible |
25b7713a MS |
269 | */ |
270 | smp_wmb(); | |
09d8b586 | 271 | OVL_I(inode)->__upperdentry = upperdentry; |
b9ac5c27 | 272 | if (!S_ISDIR(upperinode->i_mode) && inode_unhashed(inode)) { |
25b7713a | 273 | inode->i_private = upperinode; |
bbb1e54d | 274 | __insert_inode_hash(inode, (unsigned long) upperinode); |
25b7713a | 275 | } |
bbb1e54d MS |
276 | } |
277 | ||
278 | void ovl_dentry_version_inc(struct dentry *dentry) | |
279 | { | |
04a01ac7 | 280 | struct inode *inode = d_inode(dentry); |
bbb1e54d | 281 | |
04a01ac7 MS |
282 | WARN_ON(!inode_is_locked(inode)); |
283 | OVL_I(inode)->version++; | |
bbb1e54d MS |
284 | } |
285 | ||
286 | u64 ovl_dentry_version_get(struct dentry *dentry) | |
287 | { | |
04a01ac7 | 288 | struct inode *inode = d_inode(dentry); |
bbb1e54d | 289 | |
04a01ac7 MS |
290 | WARN_ON(!inode_is_locked(inode)); |
291 | return OVL_I(inode)->version; | |
bbb1e54d MS |
292 | } |
293 | ||
294 | bool ovl_is_whiteout(struct dentry *dentry) | |
295 | { | |
296 | struct inode *inode = dentry->d_inode; | |
297 | ||
298 | return inode && IS_WHITEOUT(inode); | |
299 | } | |
300 | ||
301 | struct file *ovl_path_open(struct path *path, int flags) | |
302 | { | |
303 | return dentry_open(path, flags | O_NOATIME, current_cred()); | |
304 | } | |
39d3d60a AG |
305 | |
306 | int ovl_copy_up_start(struct dentry *dentry) | |
307 | { | |
a015dafc | 308 | struct ovl_inode *oi = OVL_I(d_inode(dentry)); |
39d3d60a AG |
309 | int err; |
310 | ||
a015dafc | 311 | err = mutex_lock_interruptible(&oi->lock); |
59be0971 | 312 | if (!err && ovl_dentry_has_upper_alias(dentry)) { |
a015dafc AG |
313 | err = 1; /* Already copied up */ |
314 | mutex_unlock(&oi->lock); | |
39d3d60a | 315 | } |
39d3d60a AG |
316 | |
317 | return err; | |
318 | } | |
319 | ||
320 | void ovl_copy_up_end(struct dentry *dentry) | |
321 | { | |
a015dafc | 322 | mutex_unlock(&OVL_I(d_inode(dentry))->lock); |
39d3d60a | 323 | } |
82b749b2 | 324 | |
f3a15685 AG |
325 | bool ovl_check_dir_xattr(struct dentry *dentry, const char *name) |
326 | { | |
327 | int res; | |
328 | char val; | |
329 | ||
330 | if (!d_is_dir(dentry)) | |
331 | return false; | |
332 | ||
333 | res = vfs_getxattr(dentry, name, &val, 1); | |
334 | if (res == 1 && val == 'y') | |
335 | return true; | |
336 | ||
337 | return false; | |
338 | } | |
339 | ||
82b749b2 AG |
340 | int ovl_check_setxattr(struct dentry *dentry, struct dentry *upperdentry, |
341 | const char *name, const void *value, size_t size, | |
342 | int xerr) | |
343 | { | |
344 | int err; | |
345 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
346 | ||
347 | if (ofs->noxattr) | |
348 | return xerr; | |
349 | ||
350 | err = ovl_do_setxattr(upperdentry, name, value, size, 0); | |
351 | ||
352 | if (err == -EOPNOTSUPP) { | |
353 | pr_warn("overlayfs: cannot set %s xattr on upper\n", name); | |
354 | ofs->noxattr = true; | |
355 | return xerr; | |
356 | } | |
357 | ||
358 | return err; | |
359 | } | |
f3a15685 AG |
360 | |
361 | int ovl_set_impure(struct dentry *dentry, struct dentry *upperdentry) | |
362 | { | |
363 | int err; | |
f3a15685 | 364 | |
13c72075 | 365 | if (ovl_test_flag(OVL_IMPURE, d_inode(dentry))) |
f3a15685 AG |
366 | return 0; |
367 | ||
368 | /* | |
369 | * Do not fail when upper doesn't support xattrs. | |
370 | * Upper inodes won't have origin nor redirect xattr anyway. | |
371 | */ | |
372 | err = ovl_check_setxattr(dentry, upperdentry, OVL_XATTR_IMPURE, | |
373 | "y", 1, 0); | |
374 | if (!err) | |
13c72075 | 375 | ovl_set_flag(OVL_IMPURE, d_inode(dentry)); |
f3a15685 AG |
376 | |
377 | return err; | |
378 | } | |
13c72075 MS |
379 | |
380 | void ovl_set_flag(unsigned long flag, struct inode *inode) | |
381 | { | |
382 | set_bit(flag, &OVL_I(inode)->flags); | |
383 | } | |
384 | ||
385 | bool ovl_test_flag(unsigned long flag, struct inode *inode) | |
386 | { | |
387 | return test_bit(flag, &OVL_I(inode)->flags); | |
388 | } | |
ad0af710 AG |
389 | |
390 | /** | |
391 | * Caller must hold a reference to inode to prevent it from being freed while | |
392 | * it is marked inuse. | |
393 | */ | |
394 | bool ovl_inuse_trylock(struct dentry *dentry) | |
395 | { | |
396 | struct inode *inode = d_inode(dentry); | |
397 | bool locked = false; | |
398 | ||
399 | spin_lock(&inode->i_lock); | |
400 | if (!(inode->i_state & I_OVL_INUSE)) { | |
401 | inode->i_state |= I_OVL_INUSE; | |
402 | locked = true; | |
403 | } | |
404 | spin_unlock(&inode->i_lock); | |
405 | ||
406 | return locked; | |
407 | } | |
408 | ||
409 | void ovl_inuse_unlock(struct dentry *dentry) | |
410 | { | |
411 | if (dentry) { | |
412 | struct inode *inode = d_inode(dentry); | |
413 | ||
414 | spin_lock(&inode->i_lock); | |
415 | WARN_ON(!(inode->i_state & I_OVL_INUSE)); | |
416 | inode->i_state &= ~I_OVL_INUSE; | |
417 | spin_unlock(&inode->i_lock); | |
418 | } | |
419 | } | |
5f8415d6 | 420 | |
caf70cb2 AG |
421 | /* Called must hold OVL_I(inode)->oi_lock */ |
422 | static void ovl_cleanup_index(struct dentry *dentry) | |
423 | { | |
424 | struct inode *dir = ovl_indexdir(dentry->d_sb)->d_inode; | |
425 | struct dentry *lowerdentry = ovl_dentry_lower(dentry); | |
426 | struct dentry *upperdentry = ovl_dentry_upper(dentry); | |
427 | struct dentry *index = NULL; | |
428 | struct inode *inode; | |
429 | struct qstr name; | |
430 | int err; | |
431 | ||
432 | err = ovl_get_index_name(lowerdentry, &name); | |
433 | if (err) | |
434 | goto fail; | |
435 | ||
436 | inode = d_inode(upperdentry); | |
437 | if (inode->i_nlink != 1) { | |
438 | pr_warn_ratelimited("overlayfs: cleanup linked index (%pd2, ino=%lu, nlink=%u)\n", | |
439 | upperdentry, inode->i_ino, inode->i_nlink); | |
440 | /* | |
441 | * We either have a bug with persistent union nlink or a lower | |
442 | * hardlink was added while overlay is mounted. Adding a lower | |
443 | * hardlink and then unlinking all overlay hardlinks would drop | |
444 | * overlay nlink to zero before all upper inodes are unlinked. | |
445 | * As a safety measure, when that situation is detected, set | |
446 | * the overlay nlink to the index inode nlink minus one for the | |
447 | * index entry itself. | |
448 | */ | |
449 | set_nlink(d_inode(dentry), inode->i_nlink - 1); | |
450 | ovl_set_nlink_upper(dentry); | |
451 | goto out; | |
452 | } | |
453 | ||
454 | inode_lock_nested(dir, I_MUTEX_PARENT); | |
455 | /* TODO: whiteout instead of cleanup to block future open by handle */ | |
456 | index = lookup_one_len(name.name, ovl_indexdir(dentry->d_sb), name.len); | |
457 | err = PTR_ERR(index); | |
458 | if (!IS_ERR(index)) | |
459 | err = ovl_cleanup(dir, index); | |
460 | inode_unlock(dir); | |
461 | if (err) | |
462 | goto fail; | |
463 | ||
464 | out: | |
465 | dput(index); | |
466 | return; | |
467 | ||
468 | fail: | |
469 | pr_err("overlayfs: cleanup index of '%pd2' failed (%i)\n", dentry, err); | |
470 | goto out; | |
471 | } | |
472 | ||
5f8415d6 AG |
473 | /* |
474 | * Operations that change overlay inode and upper inode nlink need to be | |
475 | * synchronized with copy up for persistent nlink accounting. | |
476 | */ | |
477 | int ovl_nlink_start(struct dentry *dentry, bool *locked) | |
478 | { | |
479 | struct ovl_inode *oi = OVL_I(d_inode(dentry)); | |
480 | const struct cred *old_cred; | |
481 | int err; | |
482 | ||
483 | if (!d_inode(dentry) || d_is_dir(dentry)) | |
484 | return 0; | |
485 | ||
486 | /* | |
487 | * With inodes index is enabled, we store the union overlay nlink | |
488 | * in an xattr on the index inode. When whiting out lower hardlinks | |
489 | * we need to decrement the overlay persistent nlink, but before the | |
490 | * first copy up, we have no upper index inode to store the xattr. | |
491 | * | |
492 | * As a workaround, before whiteout/rename over of a lower hardlink, | |
493 | * copy up to create the upper index. Creating the upper index will | |
494 | * initialize the overlay nlink, so it could be dropped if unlink | |
495 | * or rename succeeds. | |
496 | * | |
497 | * TODO: implement metadata only index copy up when called with | |
498 | * ovl_copy_up_flags(dentry, O_PATH). | |
499 | */ | |
500 | if (ovl_indexdir(dentry->d_sb) && !ovl_dentry_has_upper_alias(dentry) && | |
501 | d_inode(ovl_dentry_lower(dentry))->i_nlink > 1) { | |
502 | err = ovl_copy_up(dentry); | |
503 | if (err) | |
504 | return err; | |
505 | } | |
506 | ||
507 | err = mutex_lock_interruptible(&oi->lock); | |
508 | if (err) | |
509 | return err; | |
510 | ||
511 | if (!ovl_test_flag(OVL_INDEX, d_inode(dentry))) | |
512 | goto out; | |
513 | ||
514 | old_cred = ovl_override_creds(dentry->d_sb); | |
515 | /* | |
516 | * The overlay inode nlink should be incremented/decremented IFF the | |
517 | * upper operation succeeds, along with nlink change of upper inode. | |
518 | * Therefore, before link/unlink/rename, we store the union nlink | |
519 | * value relative to the upper inode nlink in an upper inode xattr. | |
520 | */ | |
521 | err = ovl_set_nlink_upper(dentry); | |
522 | revert_creds(old_cred); | |
523 | ||
524 | out: | |
525 | if (err) | |
526 | mutex_unlock(&oi->lock); | |
527 | else | |
528 | *locked = true; | |
529 | ||
530 | return err; | |
531 | } | |
532 | ||
533 | void ovl_nlink_end(struct dentry *dentry, bool locked) | |
534 | { | |
caf70cb2 AG |
535 | if (locked) { |
536 | if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) && | |
537 | d_inode(dentry)->i_nlink == 0) { | |
538 | const struct cred *old_cred; | |
539 | ||
540 | old_cred = ovl_override_creds(dentry->d_sb); | |
541 | ovl_cleanup_index(dentry); | |
542 | revert_creds(old_cred); | |
543 | } | |
544 | ||
5f8415d6 | 545 | mutex_unlock(&OVL_I(d_inode(dentry))->lock); |
caf70cb2 | 546 | } |
5f8415d6 | 547 | } |