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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/namei.h> | |
cf9a6784 | 12 | #include <linux/pagemap.h> |
e9be9d5e MS |
13 | #include <linux/xattr.h> |
14 | #include <linux/security.h> | |
15 | #include <linux/mount.h> | |
16 | #include <linux/slab.h> | |
17 | #include <linux/parser.h> | |
18 | #include <linux/module.h> | |
19 | #include <linux/sched.h> | |
cc259639 | 20 | #include <linux/statfs.h> |
f45827e8 | 21 | #include <linux/seq_file.h> |
d837a49b | 22 | #include <linux/posix_acl_xattr.h> |
e9be9d5e MS |
23 | #include "overlayfs.h" |
24 | ||
25 | MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>"); | |
26 | MODULE_DESCRIPTION("Overlay filesystem"); | |
27 | MODULE_LICENSE("GPL"); | |
28 | ||
f45827e8 EZ |
29 | struct ovl_config { |
30 | char *lowerdir; | |
31 | char *upperdir; | |
32 | char *workdir; | |
8d3095f4 | 33 | bool default_permissions; |
f45827e8 EZ |
34 | }; |
35 | ||
e9be9d5e MS |
36 | /* private information held for overlayfs's superblock */ |
37 | struct ovl_fs { | |
38 | struct vfsmount *upper_mnt; | |
dd662667 MS |
39 | unsigned numlower; |
40 | struct vfsmount **lower_mnt; | |
e9be9d5e | 41 | struct dentry *workdir; |
cc259639 | 42 | long lower_namelen; |
f45827e8 EZ |
43 | /* pathnames of lower and upper dirs, for show_options */ |
44 | struct ovl_config config; | |
3fe6e52f AM |
45 | /* creds of process who forced instantiation of super block */ |
46 | const struct cred *creator_cred; | |
e9be9d5e MS |
47 | }; |
48 | ||
49 | struct ovl_dir_cache; | |
50 | ||
51 | /* private information held for every overlayfs dentry */ | |
52 | struct ovl_entry { | |
53 | struct dentry *__upperdentry; | |
e9be9d5e MS |
54 | struct ovl_dir_cache *cache; |
55 | union { | |
56 | struct { | |
57 | u64 version; | |
58 | bool opaque; | |
59 | }; | |
60 | struct rcu_head rcu; | |
61 | }; | |
dd662667 MS |
62 | unsigned numlower; |
63 | struct path lowerstack[]; | |
e9be9d5e MS |
64 | }; |
65 | ||
a78d9f0d MS |
66 | #define OVL_MAX_STACK 500 |
67 | ||
dd662667 MS |
68 | static struct dentry *__ovl_dentry_lower(struct ovl_entry *oe) |
69 | { | |
70 | return oe->numlower ? oe->lowerstack[0].dentry : NULL; | |
71 | } | |
e9be9d5e MS |
72 | |
73 | enum ovl_path_type ovl_path_type(struct dentry *dentry) | |
74 | { | |
75 | struct ovl_entry *oe = dentry->d_fsdata; | |
1afaba1e | 76 | enum ovl_path_type type = 0; |
e9be9d5e MS |
77 | |
78 | if (oe->__upperdentry) { | |
1afaba1e MS |
79 | type = __OVL_PATH_UPPER; |
80 | ||
45d11738 KK |
81 | /* |
82 | * Non-dir dentry can hold lower dentry from previous | |
83 | * location. Its purity depends only on opaque flag. | |
84 | */ | |
85 | if (oe->numlower && S_ISDIR(dentry->d_inode->i_mode)) | |
86 | type |= __OVL_PATH_MERGE; | |
87 | else if (!oe->opaque) | |
1afaba1e | 88 | type |= __OVL_PATH_PURE; |
9d7459d8 MS |
89 | } else { |
90 | if (oe->numlower > 1) | |
91 | type |= __OVL_PATH_MERGE; | |
e9be9d5e | 92 | } |
1afaba1e | 93 | return type; |
e9be9d5e MS |
94 | } |
95 | ||
96 | static struct dentry *ovl_upperdentry_dereference(struct ovl_entry *oe) | |
97 | { | |
71d50928 | 98 | return lockless_dereference(oe->__upperdentry); |
e9be9d5e MS |
99 | } |
100 | ||
101 | void ovl_path_upper(struct dentry *dentry, struct path *path) | |
102 | { | |
103 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
104 | struct ovl_entry *oe = dentry->d_fsdata; | |
105 | ||
106 | path->mnt = ofs->upper_mnt; | |
107 | path->dentry = ovl_upperdentry_dereference(oe); | |
108 | } | |
109 | ||
110 | enum ovl_path_type ovl_path_real(struct dentry *dentry, struct path *path) | |
111 | { | |
e9be9d5e MS |
112 | enum ovl_path_type type = ovl_path_type(dentry); |
113 | ||
1afaba1e | 114 | if (!OVL_TYPE_UPPER(type)) |
e9be9d5e MS |
115 | ovl_path_lower(dentry, path); |
116 | else | |
117 | ovl_path_upper(dentry, path); | |
118 | ||
119 | return type; | |
120 | } | |
121 | ||
122 | struct dentry *ovl_dentry_upper(struct dentry *dentry) | |
123 | { | |
124 | struct ovl_entry *oe = dentry->d_fsdata; | |
125 | ||
126 | return ovl_upperdentry_dereference(oe); | |
127 | } | |
128 | ||
129 | struct dentry *ovl_dentry_lower(struct dentry *dentry) | |
130 | { | |
131 | struct ovl_entry *oe = dentry->d_fsdata; | |
132 | ||
dd662667 | 133 | return __ovl_dentry_lower(oe); |
e9be9d5e MS |
134 | } |
135 | ||
136 | struct dentry *ovl_dentry_real(struct dentry *dentry) | |
137 | { | |
138 | struct ovl_entry *oe = dentry->d_fsdata; | |
139 | struct dentry *realdentry; | |
140 | ||
141 | realdentry = ovl_upperdentry_dereference(oe); | |
142 | if (!realdentry) | |
dd662667 | 143 | realdentry = __ovl_dentry_lower(oe); |
e9be9d5e MS |
144 | |
145 | return realdentry; | |
146 | } | |
147 | ||
39b681f8 MS |
148 | static void ovl_inode_init(struct inode *inode, struct inode *realinode, |
149 | bool is_upper) | |
e9be9d5e | 150 | { |
39b681f8 MS |
151 | WRITE_ONCE(inode->i_private, (unsigned long) realinode | |
152 | (is_upper ? OVL_ISUPPER_MASK : 0)); | |
39a25b2b VG |
153 | } |
154 | ||
8d3095f4 MS |
155 | struct vfsmount *ovl_entry_mnt_real(struct ovl_entry *oe, struct inode *inode, |
156 | bool is_upper) | |
157 | { | |
158 | if (is_upper) { | |
159 | struct ovl_fs *ofs = inode->i_sb->s_fs_info; | |
160 | ||
161 | return ofs->upper_mnt; | |
162 | } else { | |
163 | return oe->numlower ? oe->lowerstack[0].mnt : NULL; | |
164 | } | |
165 | } | |
166 | ||
e9be9d5e MS |
167 | struct ovl_dir_cache *ovl_dir_cache(struct dentry *dentry) |
168 | { | |
169 | struct ovl_entry *oe = dentry->d_fsdata; | |
170 | ||
171 | return oe->cache; | |
172 | } | |
173 | ||
174 | void ovl_set_dir_cache(struct dentry *dentry, struct ovl_dir_cache *cache) | |
175 | { | |
176 | struct ovl_entry *oe = dentry->d_fsdata; | |
177 | ||
178 | oe->cache = cache; | |
179 | } | |
180 | ||
181 | void ovl_path_lower(struct dentry *dentry, struct path *path) | |
182 | { | |
e9be9d5e MS |
183 | struct ovl_entry *oe = dentry->d_fsdata; |
184 | ||
dd662667 | 185 | *path = oe->numlower ? oe->lowerstack[0] : (struct path) { NULL, NULL }; |
e9be9d5e MS |
186 | } |
187 | ||
188 | int ovl_want_write(struct dentry *dentry) | |
189 | { | |
190 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
191 | return mnt_want_write(ofs->upper_mnt); | |
192 | } | |
193 | ||
194 | void ovl_drop_write(struct dentry *dentry) | |
195 | { | |
196 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
197 | mnt_drop_write(ofs->upper_mnt); | |
198 | } | |
199 | ||
200 | struct dentry *ovl_workdir(struct dentry *dentry) | |
201 | { | |
202 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
203 | return ofs->workdir; | |
204 | } | |
205 | ||
206 | bool ovl_dentry_is_opaque(struct dentry *dentry) | |
207 | { | |
208 | struct ovl_entry *oe = dentry->d_fsdata; | |
209 | return oe->opaque; | |
210 | } | |
211 | ||
212 | void ovl_dentry_set_opaque(struct dentry *dentry, bool opaque) | |
213 | { | |
214 | struct ovl_entry *oe = dentry->d_fsdata; | |
215 | oe->opaque = opaque; | |
216 | } | |
217 | ||
218 | void ovl_dentry_update(struct dentry *dentry, struct dentry *upperdentry) | |
219 | { | |
220 | struct ovl_entry *oe = dentry->d_fsdata; | |
221 | ||
5955102c | 222 | WARN_ON(!inode_is_locked(upperdentry->d_parent->d_inode)); |
e9be9d5e | 223 | WARN_ON(oe->__upperdentry); |
e9be9d5e MS |
224 | /* |
225 | * Make sure upperdentry is consistent before making it visible to | |
226 | * ovl_upperdentry_dereference(). | |
227 | */ | |
228 | smp_wmb(); | |
229 | oe->__upperdentry = upperdentry; | |
230 | } | |
231 | ||
39b681f8 MS |
232 | void ovl_inode_update(struct inode *inode, struct inode *upperinode) |
233 | { | |
234 | WARN_ON(!upperinode); | |
51f7e52d | 235 | WARN_ON(!inode_unhashed(inode)); |
39b681f8 MS |
236 | WRITE_ONCE(inode->i_private, |
237 | (unsigned long) upperinode | OVL_ISUPPER_MASK); | |
51f7e52d MS |
238 | if (!S_ISDIR(upperinode->i_mode)) |
239 | __insert_inode_hash(inode, (unsigned long) upperinode); | |
39b681f8 MS |
240 | } |
241 | ||
e9be9d5e MS |
242 | void ovl_dentry_version_inc(struct dentry *dentry) |
243 | { | |
244 | struct ovl_entry *oe = dentry->d_fsdata; | |
245 | ||
5955102c | 246 | WARN_ON(!inode_is_locked(dentry->d_inode)); |
e9be9d5e MS |
247 | oe->version++; |
248 | } | |
249 | ||
250 | u64 ovl_dentry_version_get(struct dentry *dentry) | |
251 | { | |
252 | struct ovl_entry *oe = dentry->d_fsdata; | |
253 | ||
5955102c | 254 | WARN_ON(!inode_is_locked(dentry->d_inode)); |
e9be9d5e MS |
255 | return oe->version; |
256 | } | |
257 | ||
258 | bool ovl_is_whiteout(struct dentry *dentry) | |
259 | { | |
260 | struct inode *inode = dentry->d_inode; | |
261 | ||
262 | return inode && IS_WHITEOUT(inode); | |
263 | } | |
264 | ||
3fe6e52f AM |
265 | const struct cred *ovl_override_creds(struct super_block *sb) |
266 | { | |
267 | struct ovl_fs *ofs = sb->s_fs_info; | |
268 | ||
269 | return override_creds(ofs->creator_cred); | |
270 | } | |
271 | ||
e9be9d5e MS |
272 | static bool ovl_is_opaquedir(struct dentry *dentry) |
273 | { | |
274 | int res; | |
275 | char val; | |
276 | struct inode *inode = dentry->d_inode; | |
277 | ||
278 | if (!S_ISDIR(inode->i_mode) || !inode->i_op->getxattr) | |
279 | return false; | |
280 | ||
ce23e640 | 281 | res = inode->i_op->getxattr(dentry, inode, OVL_XATTR_OPAQUE, &val, 1); |
e9be9d5e MS |
282 | if (res == 1 && val == 'y') |
283 | return true; | |
284 | ||
285 | return false; | |
286 | } | |
287 | ||
288 | static void ovl_dentry_release(struct dentry *dentry) | |
289 | { | |
290 | struct ovl_entry *oe = dentry->d_fsdata; | |
291 | ||
292 | if (oe) { | |
dd662667 MS |
293 | unsigned int i; |
294 | ||
e9be9d5e | 295 | dput(oe->__upperdentry); |
dd662667 MS |
296 | for (i = 0; i < oe->numlower; i++) |
297 | dput(oe->lowerstack[i].dentry); | |
e9be9d5e MS |
298 | kfree_rcu(oe, rcu); |
299 | } | |
300 | } | |
301 | ||
2d902671 MS |
302 | static struct dentry *ovl_d_real(struct dentry *dentry, |
303 | const struct inode *inode, | |
304 | unsigned int open_flags) | |
d101a125 MS |
305 | { |
306 | struct dentry *real; | |
307 | ||
308 | if (d_is_dir(dentry)) { | |
309 | if (!inode || inode == d_inode(dentry)) | |
310 | return dentry; | |
311 | goto bug; | |
312 | } | |
313 | ||
2d902671 MS |
314 | if (d_is_negative(dentry)) |
315 | return dentry; | |
316 | ||
317 | if (open_flags) { | |
318 | int err = ovl_open_maybe_copy_up(dentry, open_flags); | |
319 | ||
320 | if (err) | |
321 | return ERR_PTR(err); | |
322 | } | |
323 | ||
d101a125 MS |
324 | real = ovl_dentry_upper(dentry); |
325 | if (real && (!inode || inode == d_inode(real))) | |
326 | return real; | |
327 | ||
328 | real = ovl_dentry_lower(dentry); | |
329 | if (!real) | |
330 | goto bug; | |
331 | ||
332 | if (!inode || inode == d_inode(real)) | |
333 | return real; | |
334 | ||
335 | /* Handle recursion */ | |
2d902671 | 336 | return d_real(real, inode, open_flags); |
d101a125 | 337 | bug: |
656189d2 | 338 | WARN(1, "ovl_d_real(%pd4, %s:%lu): real dentry not found\n", dentry, |
d101a125 MS |
339 | inode ? inode->i_sb->s_id : "NULL", inode ? inode->i_ino : 0); |
340 | return dentry; | |
341 | } | |
342 | ||
7c03b5d4 MS |
343 | static int ovl_dentry_revalidate(struct dentry *dentry, unsigned int flags) |
344 | { | |
345 | struct ovl_entry *oe = dentry->d_fsdata; | |
346 | unsigned int i; | |
347 | int ret = 1; | |
348 | ||
349 | for (i = 0; i < oe->numlower; i++) { | |
350 | struct dentry *d = oe->lowerstack[i].dentry; | |
351 | ||
352 | if (d->d_flags & DCACHE_OP_REVALIDATE) { | |
353 | ret = d->d_op->d_revalidate(d, flags); | |
354 | if (ret < 0) | |
355 | return ret; | |
356 | if (!ret) { | |
357 | if (!(flags & LOOKUP_RCU)) | |
358 | d_invalidate(d); | |
359 | return -ESTALE; | |
360 | } | |
361 | } | |
362 | } | |
363 | return 1; | |
364 | } | |
365 | ||
366 | static int ovl_dentry_weak_revalidate(struct dentry *dentry, unsigned int flags) | |
367 | { | |
368 | struct ovl_entry *oe = dentry->d_fsdata; | |
369 | unsigned int i; | |
370 | int ret = 1; | |
371 | ||
372 | for (i = 0; i < oe->numlower; i++) { | |
373 | struct dentry *d = oe->lowerstack[i].dentry; | |
374 | ||
375 | if (d->d_flags & DCACHE_OP_WEAK_REVALIDATE) { | |
376 | ret = d->d_op->d_weak_revalidate(d, flags); | |
377 | if (ret <= 0) | |
378 | break; | |
379 | } | |
380 | } | |
381 | return ret; | |
382 | } | |
383 | ||
e9be9d5e MS |
384 | static const struct dentry_operations ovl_dentry_operations = { |
385 | .d_release = ovl_dentry_release, | |
d101a125 | 386 | .d_real = ovl_d_real, |
e9be9d5e MS |
387 | }; |
388 | ||
7c03b5d4 MS |
389 | static const struct dentry_operations ovl_reval_dentry_operations = { |
390 | .d_release = ovl_dentry_release, | |
d101a125 | 391 | .d_real = ovl_d_real, |
7c03b5d4 MS |
392 | .d_revalidate = ovl_dentry_revalidate, |
393 | .d_weak_revalidate = ovl_dentry_weak_revalidate, | |
394 | }; | |
395 | ||
dd662667 | 396 | static struct ovl_entry *ovl_alloc_entry(unsigned int numlower) |
e9be9d5e | 397 | { |
dd662667 MS |
398 | size_t size = offsetof(struct ovl_entry, lowerstack[numlower]); |
399 | struct ovl_entry *oe = kzalloc(size, GFP_KERNEL); | |
400 | ||
401 | if (oe) | |
402 | oe->numlower = numlower; | |
403 | ||
404 | return oe; | |
e9be9d5e MS |
405 | } |
406 | ||
7c03b5d4 MS |
407 | static bool ovl_dentry_remote(struct dentry *dentry) |
408 | { | |
409 | return dentry->d_flags & | |
76bc8e28 MS |
410 | (DCACHE_OP_REVALIDATE | DCACHE_OP_WEAK_REVALIDATE | |
411 | DCACHE_OP_REAL); | |
7c03b5d4 MS |
412 | } |
413 | ||
414 | static bool ovl_dentry_weird(struct dentry *dentry) | |
415 | { | |
416 | return dentry->d_flags & (DCACHE_NEED_AUTOMOUNT | | |
417 | DCACHE_MANAGE_TRANSIT | | |
418 | DCACHE_OP_HASH | | |
419 | DCACHE_OP_COMPARE); | |
420 | } | |
421 | ||
c1b2cc1a MS |
422 | static inline struct dentry *ovl_lookup_real(struct super_block *ovl_sb, |
423 | struct dentry *dir, | |
29c42e80 | 424 | const struct qstr *name) |
e9be9d5e | 425 | { |
c1b2cc1a | 426 | const struct cred *old_cred; |
e9be9d5e MS |
427 | struct dentry *dentry; |
428 | ||
c1b2cc1a MS |
429 | old_cred = ovl_override_creds(ovl_sb); |
430 | dentry = lookup_one_len_unlocked(name->name, dir, name->len); | |
431 | revert_creds(old_cred); | |
e9be9d5e MS |
432 | |
433 | if (IS_ERR(dentry)) { | |
434 | if (PTR_ERR(dentry) == -ENOENT) | |
435 | dentry = NULL; | |
436 | } else if (!dentry->d_inode) { | |
437 | dput(dentry); | |
438 | dentry = NULL; | |
7c03b5d4 | 439 | } else if (ovl_dentry_weird(dentry)) { |
a6f15d9a | 440 | dput(dentry); |
7c03b5d4 | 441 | /* Don't support traversing automounts and other weirdness */ |
a6f15d9a | 442 | dentry = ERR_PTR(-EREMOTE); |
e9be9d5e MS |
443 | } |
444 | return dentry; | |
445 | } | |
446 | ||
5ef88da5 MS |
447 | /* |
448 | * Returns next layer in stack starting from top. | |
449 | * Returns -1 if this is the last layer. | |
450 | */ | |
451 | int ovl_path_next(int idx, struct dentry *dentry, struct path *path) | |
452 | { | |
453 | struct ovl_entry *oe = dentry->d_fsdata; | |
454 | ||
455 | BUG_ON(idx < 0); | |
456 | if (idx == 0) { | |
457 | ovl_path_upper(dentry, path); | |
458 | if (path->dentry) | |
459 | return oe->numlower ? 1 : -1; | |
460 | idx++; | |
461 | } | |
462 | BUG_ON(idx > oe->numlower); | |
463 | *path = oe->lowerstack[idx - 1]; | |
464 | ||
465 | return (idx < oe->numlower) ? idx + 1 : -1; | |
466 | } | |
467 | ||
e9be9d5e MS |
468 | struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, |
469 | unsigned int flags) | |
470 | { | |
471 | struct ovl_entry *oe; | |
3d3c6b89 MS |
472 | struct ovl_entry *poe = dentry->d_parent->d_fsdata; |
473 | struct path *stack = NULL; | |
474 | struct dentry *upperdir, *upperdentry = NULL; | |
475 | unsigned int ctr = 0; | |
e9be9d5e | 476 | struct inode *inode = NULL; |
3d3c6b89 MS |
477 | bool upperopaque = false; |
478 | struct dentry *this, *prev = NULL; | |
479 | unsigned int i; | |
e9be9d5e MS |
480 | int err; |
481 | ||
3d3c6b89 | 482 | upperdir = ovl_upperdentry_dereference(poe); |
e9be9d5e | 483 | if (upperdir) { |
c1b2cc1a | 484 | this = ovl_lookup_real(dentry->d_sb, upperdir, &dentry->d_name); |
3d3c6b89 MS |
485 | err = PTR_ERR(this); |
486 | if (IS_ERR(this)) | |
487 | goto out; | |
488 | ||
3e01cee3 | 489 | if (this) { |
7c03b5d4 MS |
490 | if (unlikely(ovl_dentry_remote(this))) { |
491 | dput(this); | |
492 | err = -EREMOTE; | |
493 | goto out; | |
494 | } | |
3d3c6b89 MS |
495 | if (ovl_is_whiteout(this)) { |
496 | dput(this); | |
497 | this = NULL; | |
498 | upperopaque = true; | |
3e01cee3 | 499 | } else if (poe->numlower && ovl_is_opaquedir(this)) { |
3d3c6b89 | 500 | upperopaque = true; |
e9be9d5e MS |
501 | } |
502 | } | |
3d3c6b89 | 503 | upperdentry = prev = this; |
e9be9d5e | 504 | } |
3d3c6b89 MS |
505 | |
506 | if (!upperopaque && poe->numlower) { | |
507 | err = -ENOMEM; | |
508 | stack = kcalloc(poe->numlower, sizeof(struct path), GFP_KERNEL); | |
509 | if (!stack) | |
510 | goto out_put_upper; | |
e9be9d5e MS |
511 | } |
512 | ||
3d3c6b89 MS |
513 | for (i = 0; !upperopaque && i < poe->numlower; i++) { |
514 | bool opaque = false; | |
515 | struct path lowerpath = poe->lowerstack[i]; | |
516 | ||
c1b2cc1a MS |
517 | this = ovl_lookup_real(dentry->d_sb, |
518 | lowerpath.dentry, &dentry->d_name); | |
3d3c6b89 | 519 | err = PTR_ERR(this); |
09e10322 MS |
520 | if (IS_ERR(this)) { |
521 | /* | |
522 | * If it's positive, then treat ENAMETOOLONG as ENOENT. | |
523 | */ | |
524 | if (err == -ENAMETOOLONG && (upperdentry || ctr)) | |
525 | continue; | |
3d3c6b89 | 526 | goto out_put; |
09e10322 | 527 | } |
3d3c6b89 MS |
528 | if (!this) |
529 | continue; | |
3e01cee3 MS |
530 | if (ovl_is_whiteout(this)) { |
531 | dput(this); | |
532 | break; | |
533 | } | |
3d3c6b89 | 534 | /* |
3e01cee3 MS |
535 | * Only makes sense to check opaque dir if this is not the |
536 | * lowermost layer. | |
3d3c6b89 | 537 | */ |
3e01cee3 MS |
538 | if (i < poe->numlower - 1 && ovl_is_opaquedir(this)) |
539 | opaque = true; | |
a425c037 | 540 | |
541 | if (prev && (!S_ISDIR(prev->d_inode->i_mode) || | |
542 | !S_ISDIR(this->d_inode->i_mode))) { | |
543 | /* | |
544 | * FIXME: check for upper-opaqueness maybe better done | |
545 | * in remove code. | |
546 | */ | |
3d3c6b89 MS |
547 | if (prev == upperdentry) |
548 | upperopaque = true; | |
549 | dput(this); | |
550 | break; | |
551 | } | |
a425c037 | 552 | /* |
553 | * If this is a non-directory then stop here. | |
554 | */ | |
555 | if (!S_ISDIR(this->d_inode->i_mode)) | |
556 | opaque = true; | |
557 | ||
3d3c6b89 MS |
558 | stack[ctr].dentry = this; |
559 | stack[ctr].mnt = lowerpath.mnt; | |
560 | ctr++; | |
561 | prev = this; | |
562 | if (opaque) | |
563 | break; | |
e9be9d5e MS |
564 | } |
565 | ||
3d3c6b89 MS |
566 | oe = ovl_alloc_entry(ctr); |
567 | err = -ENOMEM; | |
568 | if (!oe) | |
569 | goto out_put; | |
570 | ||
571 | if (upperdentry || ctr) { | |
e9be9d5e | 572 | struct dentry *realdentry; |
39b681f8 | 573 | struct inode *realinode; |
e9be9d5e | 574 | |
3d3c6b89 | 575 | realdentry = upperdentry ? upperdentry : stack[0].dentry; |
39b681f8 | 576 | realinode = d_inode(realdentry); |
3d3c6b89 | 577 | |
e9be9d5e | 578 | err = -ENOMEM; |
51f7e52d MS |
579 | if (upperdentry && !d_is_dir(upperdentry)) { |
580 | inode = ovl_get_inode(dentry->d_sb, realinode); | |
581 | } else { | |
582 | inode = ovl_new_inode(dentry->d_sb, realinode->i_mode); | |
583 | if (inode) | |
584 | ovl_inode_init(inode, realinode, !!upperdentry); | |
585 | } | |
e9be9d5e | 586 | if (!inode) |
3d3c6b89 | 587 | goto out_free_oe; |
e9be9d5e MS |
588 | ovl_copyattr(realdentry->d_inode, inode); |
589 | } | |
590 | ||
3d3c6b89 | 591 | oe->opaque = upperopaque; |
e9be9d5e | 592 | oe->__upperdentry = upperdentry; |
3d3c6b89 MS |
593 | memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr); |
594 | kfree(stack); | |
e9be9d5e MS |
595 | dentry->d_fsdata = oe; |
596 | d_add(dentry, inode); | |
597 | ||
598 | return NULL; | |
599 | ||
3d3c6b89 | 600 | out_free_oe: |
e9be9d5e | 601 | kfree(oe); |
3d3c6b89 MS |
602 | out_put: |
603 | for (i = 0; i < ctr; i++) | |
604 | dput(stack[i].dentry); | |
605 | kfree(stack); | |
606 | out_put_upper: | |
607 | dput(upperdentry); | |
e9be9d5e MS |
608 | out: |
609 | return ERR_PTR(err); | |
610 | } | |
611 | ||
612 | struct file *ovl_path_open(struct path *path, int flags) | |
613 | { | |
d719e8f2 | 614 | return dentry_open(path, flags | O_NOATIME, current_cred()); |
e9be9d5e MS |
615 | } |
616 | ||
617 | static void ovl_put_super(struct super_block *sb) | |
618 | { | |
619 | struct ovl_fs *ufs = sb->s_fs_info; | |
dd662667 | 620 | unsigned i; |
e9be9d5e MS |
621 | |
622 | dput(ufs->workdir); | |
623 | mntput(ufs->upper_mnt); | |
dd662667 MS |
624 | for (i = 0; i < ufs->numlower; i++) |
625 | mntput(ufs->lower_mnt[i]); | |
5ffdbe8b | 626 | kfree(ufs->lower_mnt); |
e9be9d5e | 627 | |
f45827e8 EZ |
628 | kfree(ufs->config.lowerdir); |
629 | kfree(ufs->config.upperdir); | |
630 | kfree(ufs->config.workdir); | |
3fe6e52f | 631 | put_cred(ufs->creator_cred); |
e9be9d5e MS |
632 | kfree(ufs); |
633 | } | |
634 | ||
cc259639 AW |
635 | /** |
636 | * ovl_statfs | |
637 | * @sb: The overlayfs super block | |
638 | * @buf: The struct kstatfs to fill in with stats | |
639 | * | |
640 | * Get the filesystem statistics. As writes always target the upper layer | |
4ebc5818 | 641 | * filesystem pass the statfs to the upper filesystem (if it exists) |
cc259639 AW |
642 | */ |
643 | static int ovl_statfs(struct dentry *dentry, struct kstatfs *buf) | |
644 | { | |
645 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
646 | struct dentry *root_dentry = dentry->d_sb->s_root; | |
647 | struct path path; | |
648 | int err; | |
649 | ||
4ebc5818 | 650 | ovl_path_real(root_dentry, &path); |
cc259639 AW |
651 | |
652 | err = vfs_statfs(&path, buf); | |
653 | if (!err) { | |
654 | buf->f_namelen = max(buf->f_namelen, ofs->lower_namelen); | |
655 | buf->f_type = OVERLAYFS_SUPER_MAGIC; | |
656 | } | |
657 | ||
658 | return err; | |
659 | } | |
660 | ||
f45827e8 EZ |
661 | /** |
662 | * ovl_show_options | |
663 | * | |
664 | * Prints the mount options for a given superblock. | |
665 | * Returns zero; does not fail. | |
666 | */ | |
667 | static int ovl_show_options(struct seq_file *m, struct dentry *dentry) | |
668 | { | |
669 | struct super_block *sb = dentry->d_sb; | |
670 | struct ovl_fs *ufs = sb->s_fs_info; | |
671 | ||
a068acf2 | 672 | seq_show_option(m, "lowerdir", ufs->config.lowerdir); |
53a08cb9 | 673 | if (ufs->config.upperdir) { |
a068acf2 KC |
674 | seq_show_option(m, "upperdir", ufs->config.upperdir); |
675 | seq_show_option(m, "workdir", ufs->config.workdir); | |
53a08cb9 | 676 | } |
8d3095f4 MS |
677 | if (ufs->config.default_permissions) |
678 | seq_puts(m, ",default_permissions"); | |
f45827e8 EZ |
679 | return 0; |
680 | } | |
681 | ||
3cdf6fe9 SL |
682 | static int ovl_remount(struct super_block *sb, int *flags, char *data) |
683 | { | |
684 | struct ovl_fs *ufs = sb->s_fs_info; | |
685 | ||
cc6f67bc | 686 | if (!(*flags & MS_RDONLY) && (!ufs->upper_mnt || !ufs->workdir)) |
3cdf6fe9 SL |
687 | return -EROFS; |
688 | ||
689 | return 0; | |
690 | } | |
691 | ||
e9be9d5e MS |
692 | static const struct super_operations ovl_super_operations = { |
693 | .put_super = ovl_put_super, | |
cc259639 | 694 | .statfs = ovl_statfs, |
f45827e8 | 695 | .show_options = ovl_show_options, |
3cdf6fe9 | 696 | .remount_fs = ovl_remount, |
eead4f2d | 697 | .drop_inode = generic_delete_inode, |
e9be9d5e MS |
698 | }; |
699 | ||
700 | enum { | |
701 | OPT_LOWERDIR, | |
702 | OPT_UPPERDIR, | |
703 | OPT_WORKDIR, | |
8d3095f4 | 704 | OPT_DEFAULT_PERMISSIONS, |
e9be9d5e MS |
705 | OPT_ERR, |
706 | }; | |
707 | ||
708 | static const match_table_t ovl_tokens = { | |
709 | {OPT_LOWERDIR, "lowerdir=%s"}, | |
710 | {OPT_UPPERDIR, "upperdir=%s"}, | |
711 | {OPT_WORKDIR, "workdir=%s"}, | |
8d3095f4 | 712 | {OPT_DEFAULT_PERMISSIONS, "default_permissions"}, |
e9be9d5e MS |
713 | {OPT_ERR, NULL} |
714 | }; | |
715 | ||
91c77947 MS |
716 | static char *ovl_next_opt(char **s) |
717 | { | |
718 | char *sbegin = *s; | |
719 | char *p; | |
720 | ||
721 | if (sbegin == NULL) | |
722 | return NULL; | |
723 | ||
724 | for (p = sbegin; *p; p++) { | |
725 | if (*p == '\\') { | |
726 | p++; | |
727 | if (!*p) | |
728 | break; | |
729 | } else if (*p == ',') { | |
730 | *p = '\0'; | |
731 | *s = p + 1; | |
732 | return sbegin; | |
733 | } | |
734 | } | |
735 | *s = NULL; | |
736 | return sbegin; | |
737 | } | |
738 | ||
e9be9d5e MS |
739 | static int ovl_parse_opt(char *opt, struct ovl_config *config) |
740 | { | |
741 | char *p; | |
742 | ||
91c77947 | 743 | while ((p = ovl_next_opt(&opt)) != NULL) { |
e9be9d5e MS |
744 | int token; |
745 | substring_t args[MAX_OPT_ARGS]; | |
746 | ||
747 | if (!*p) | |
748 | continue; | |
749 | ||
750 | token = match_token(p, ovl_tokens, args); | |
751 | switch (token) { | |
752 | case OPT_UPPERDIR: | |
753 | kfree(config->upperdir); | |
754 | config->upperdir = match_strdup(&args[0]); | |
755 | if (!config->upperdir) | |
756 | return -ENOMEM; | |
757 | break; | |
758 | ||
759 | case OPT_LOWERDIR: | |
760 | kfree(config->lowerdir); | |
761 | config->lowerdir = match_strdup(&args[0]); | |
762 | if (!config->lowerdir) | |
763 | return -ENOMEM; | |
764 | break; | |
765 | ||
766 | case OPT_WORKDIR: | |
767 | kfree(config->workdir); | |
768 | config->workdir = match_strdup(&args[0]); | |
769 | if (!config->workdir) | |
770 | return -ENOMEM; | |
771 | break; | |
772 | ||
8d3095f4 MS |
773 | case OPT_DEFAULT_PERMISSIONS: |
774 | config->default_permissions = true; | |
775 | break; | |
776 | ||
e9be9d5e | 777 | default: |
bead55ef | 778 | pr_err("overlayfs: unrecognized mount option \"%s\" or missing value\n", p); |
e9be9d5e MS |
779 | return -EINVAL; |
780 | } | |
781 | } | |
71cbad7e | 782 | |
783 | /* Workdir is useless in non-upper mount */ | |
784 | if (!config->upperdir && config->workdir) { | |
785 | pr_info("overlayfs: option \"workdir=%s\" is useless in a non-upper mount, ignore\n", | |
786 | config->workdir); | |
787 | kfree(config->workdir); | |
788 | config->workdir = NULL; | |
789 | } | |
790 | ||
e9be9d5e MS |
791 | return 0; |
792 | } | |
793 | ||
794 | #define OVL_WORKDIR_NAME "work" | |
795 | ||
796 | static struct dentry *ovl_workdir_create(struct vfsmount *mnt, | |
797 | struct dentry *dentry) | |
798 | { | |
799 | struct inode *dir = dentry->d_inode; | |
800 | struct dentry *work; | |
801 | int err; | |
802 | bool retried = false; | |
803 | ||
804 | err = mnt_want_write(mnt); | |
805 | if (err) | |
806 | return ERR_PTR(err); | |
807 | ||
5955102c | 808 | inode_lock_nested(dir, I_MUTEX_PARENT); |
e9be9d5e MS |
809 | retry: |
810 | work = lookup_one_len(OVL_WORKDIR_NAME, dentry, | |
811 | strlen(OVL_WORKDIR_NAME)); | |
812 | ||
813 | if (!IS_ERR(work)) { | |
814 | struct kstat stat = { | |
815 | .mode = S_IFDIR | 0, | |
816 | }; | |
c11b9fdd MS |
817 | struct iattr attr = { |
818 | .ia_valid = ATTR_MODE, | |
819 | .ia_mode = stat.mode, | |
820 | }; | |
e9be9d5e MS |
821 | |
822 | if (work->d_inode) { | |
823 | err = -EEXIST; | |
824 | if (retried) | |
825 | goto out_dput; | |
826 | ||
827 | retried = true; | |
eea2fb48 | 828 | ovl_workdir_cleanup(dir, mnt, work, 0); |
e9be9d5e MS |
829 | dput(work); |
830 | goto retry; | |
831 | } | |
832 | ||
833 | err = ovl_create_real(dir, work, &stat, NULL, NULL, true); | |
834 | if (err) | |
835 | goto out_dput; | |
c11b9fdd MS |
836 | |
837 | err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_DEFAULT); | |
e1ff3dd1 | 838 | if (err && err != -ENODATA && err != -EOPNOTSUPP) |
c11b9fdd MS |
839 | goto out_dput; |
840 | ||
841 | err = vfs_removexattr(work, XATTR_NAME_POSIX_ACL_ACCESS); | |
e1ff3dd1 | 842 | if (err && err != -ENODATA && err != -EOPNOTSUPP) |
c11b9fdd MS |
843 | goto out_dput; |
844 | ||
845 | /* Clear any inherited mode bits */ | |
846 | inode_lock(work->d_inode); | |
847 | err = notify_change(work, &attr, NULL); | |
848 | inode_unlock(work->d_inode); | |
849 | if (err) | |
850 | goto out_dput; | |
e9be9d5e MS |
851 | } |
852 | out_unlock: | |
5955102c | 853 | inode_unlock(dir); |
e9be9d5e MS |
854 | mnt_drop_write(mnt); |
855 | ||
856 | return work; | |
857 | ||
858 | out_dput: | |
859 | dput(work); | |
860 | work = ERR_PTR(err); | |
861 | goto out_unlock; | |
862 | } | |
863 | ||
91c77947 MS |
864 | static void ovl_unescape(char *s) |
865 | { | |
866 | char *d = s; | |
867 | ||
868 | for (;; s++, d++) { | |
869 | if (*s == '\\') | |
870 | s++; | |
871 | *d = *s; | |
872 | if (!*s) | |
873 | break; | |
874 | } | |
875 | } | |
876 | ||
ab508822 MS |
877 | static int ovl_mount_dir_noesc(const char *name, struct path *path) |
878 | { | |
a78d9f0d | 879 | int err = -EINVAL; |
ab508822 | 880 | |
a78d9f0d MS |
881 | if (!*name) { |
882 | pr_err("overlayfs: empty lowerdir\n"); | |
883 | goto out; | |
884 | } | |
ab508822 MS |
885 | err = kern_path(name, LOOKUP_FOLLOW, path); |
886 | if (err) { | |
887 | pr_err("overlayfs: failed to resolve '%s': %i\n", name, err); | |
888 | goto out; | |
889 | } | |
890 | err = -EINVAL; | |
7c03b5d4 | 891 | if (ovl_dentry_weird(path->dentry)) { |
ab508822 MS |
892 | pr_err("overlayfs: filesystem on '%s' not supported\n", name); |
893 | goto out_put; | |
894 | } | |
895 | if (!S_ISDIR(path->dentry->d_inode->i_mode)) { | |
896 | pr_err("overlayfs: '%s' not a directory\n", name); | |
897 | goto out_put; | |
898 | } | |
899 | return 0; | |
900 | ||
901 | out_put: | |
902 | path_put(path); | |
903 | out: | |
904 | return err; | |
905 | } | |
906 | ||
907 | static int ovl_mount_dir(const char *name, struct path *path) | |
908 | { | |
909 | int err = -ENOMEM; | |
910 | char *tmp = kstrdup(name, GFP_KERNEL); | |
911 | ||
912 | if (tmp) { | |
913 | ovl_unescape(tmp); | |
914 | err = ovl_mount_dir_noesc(tmp, path); | |
7c03b5d4 MS |
915 | |
916 | if (!err) | |
917 | if (ovl_dentry_remote(path->dentry)) { | |
918 | pr_err("overlayfs: filesystem on '%s' not supported as upperdir\n", | |
919 | tmp); | |
920 | path_put(path); | |
921 | err = -EINVAL; | |
922 | } | |
ab508822 MS |
923 | kfree(tmp); |
924 | } | |
925 | return err; | |
926 | } | |
927 | ||
928 | static int ovl_lower_dir(const char *name, struct path *path, long *namelen, | |
7c03b5d4 | 929 | int *stack_depth, bool *remote) |
ab508822 MS |
930 | { |
931 | int err; | |
932 | struct kstatfs statfs; | |
933 | ||
a78d9f0d | 934 | err = ovl_mount_dir_noesc(name, path); |
ab508822 MS |
935 | if (err) |
936 | goto out; | |
937 | ||
938 | err = vfs_statfs(path, &statfs); | |
939 | if (err) { | |
940 | pr_err("overlayfs: statfs failed on '%s'\n", name); | |
941 | goto out_put; | |
942 | } | |
943 | *namelen = max(*namelen, statfs.f_namelen); | |
944 | *stack_depth = max(*stack_depth, path->mnt->mnt_sb->s_stack_depth); | |
945 | ||
7c03b5d4 MS |
946 | if (ovl_dentry_remote(path->dentry)) |
947 | *remote = true; | |
948 | ||
ab508822 MS |
949 | return 0; |
950 | ||
951 | out_put: | |
952 | path_put(path); | |
953 | out: | |
954 | return err; | |
955 | } | |
956 | ||
e9be9d5e MS |
957 | /* Workdir should not be subdir of upperdir and vice versa */ |
958 | static bool ovl_workdir_ok(struct dentry *workdir, struct dentry *upperdir) | |
959 | { | |
960 | bool ok = false; | |
961 | ||
962 | if (workdir != upperdir) { | |
963 | ok = (lock_rename(workdir, upperdir) == NULL); | |
964 | unlock_rename(workdir, upperdir); | |
965 | } | |
966 | return ok; | |
967 | } | |
968 | ||
a78d9f0d MS |
969 | static unsigned int ovl_split_lowerdirs(char *str) |
970 | { | |
971 | unsigned int ctr = 1; | |
972 | char *s, *d; | |
973 | ||
974 | for (s = d = str;; s++, d++) { | |
975 | if (*s == '\\') { | |
976 | s++; | |
977 | } else if (*s == ':') { | |
978 | *d = '\0'; | |
979 | ctr++; | |
980 | continue; | |
981 | } | |
982 | *d = *s; | |
983 | if (!*s) | |
984 | break; | |
985 | } | |
986 | return ctr; | |
987 | } | |
988 | ||
0eb45fc3 AG |
989 | static int __maybe_unused |
990 | ovl_posix_acl_xattr_get(const struct xattr_handler *handler, | |
991 | struct dentry *dentry, struct inode *inode, | |
992 | const char *name, void *buffer, size_t size) | |
993 | { | |
994 | return ovl_xattr_get(dentry, handler->name, buffer, size); | |
995 | } | |
996 | ||
0c97be22 AG |
997 | static int __maybe_unused |
998 | ovl_posix_acl_xattr_set(const struct xattr_handler *handler, | |
999 | struct dentry *dentry, struct inode *inode, | |
1000 | const char *name, const void *value, | |
1001 | size_t size, int flags) | |
d837a49b MS |
1002 | { |
1003 | struct dentry *workdir = ovl_workdir(dentry); | |
1004 | struct inode *realinode = ovl_inode_real(inode, NULL); | |
1005 | struct posix_acl *acl = NULL; | |
1006 | int err; | |
1007 | ||
1008 | /* Check that everything is OK before copy-up */ | |
1009 | if (value) { | |
1010 | acl = posix_acl_from_xattr(&init_user_ns, value, size); | |
1011 | if (IS_ERR(acl)) | |
1012 | return PTR_ERR(acl); | |
1013 | } | |
1014 | err = -EOPNOTSUPP; | |
1015 | if (!IS_POSIXACL(d_inode(workdir))) | |
1016 | goto out_acl_release; | |
1017 | if (!realinode->i_op->set_acl) | |
1018 | goto out_acl_release; | |
1019 | if (handler->flags == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode)) { | |
1020 | err = acl ? -EACCES : 0; | |
1021 | goto out_acl_release; | |
1022 | } | |
1023 | err = -EPERM; | |
1024 | if (!inode_owner_or_capable(inode)) | |
1025 | goto out_acl_release; | |
1026 | ||
1027 | posix_acl_release(acl); | |
1028 | ||
ce31513a MS |
1029 | err = ovl_xattr_set(dentry, handler->name, value, size, flags); |
1030 | if (!err) | |
1031 | ovl_copyattr(ovl_inode_real(inode, NULL), inode); | |
1032 | ||
1033 | return err; | |
d837a49b MS |
1034 | |
1035 | out_acl_release: | |
1036 | posix_acl_release(acl); | |
1037 | return err; | |
1038 | } | |
1039 | ||
0eb45fc3 AG |
1040 | static int ovl_own_xattr_get(const struct xattr_handler *handler, |
1041 | struct dentry *dentry, struct inode *inode, | |
1042 | const char *name, void *buffer, size_t size) | |
1043 | { | |
1044 | return -EPERM; | |
1045 | } | |
1046 | ||
d837a49b MS |
1047 | static int ovl_own_xattr_set(const struct xattr_handler *handler, |
1048 | struct dentry *dentry, struct inode *inode, | |
1049 | const char *name, const void *value, | |
1050 | size_t size, int flags) | |
1051 | { | |
1052 | return -EPERM; | |
1053 | } | |
1054 | ||
0eb45fc3 AG |
1055 | static int ovl_other_xattr_get(const struct xattr_handler *handler, |
1056 | struct dentry *dentry, struct inode *inode, | |
1057 | const char *name, void *buffer, size_t size) | |
1058 | { | |
1059 | return ovl_xattr_get(dentry, name, buffer, size); | |
1060 | } | |
1061 | ||
0e585ccc AG |
1062 | static int ovl_other_xattr_set(const struct xattr_handler *handler, |
1063 | struct dentry *dentry, struct inode *inode, | |
1064 | const char *name, const void *value, | |
1065 | size_t size, int flags) | |
1066 | { | |
1067 | return ovl_xattr_set(dentry, name, value, size, flags); | |
1068 | } | |
1069 | ||
0c97be22 AG |
1070 | static const struct xattr_handler __maybe_unused |
1071 | ovl_posix_acl_access_xattr_handler = { | |
d837a49b MS |
1072 | .name = XATTR_NAME_POSIX_ACL_ACCESS, |
1073 | .flags = ACL_TYPE_ACCESS, | |
0eb45fc3 | 1074 | .get = ovl_posix_acl_xattr_get, |
d837a49b MS |
1075 | .set = ovl_posix_acl_xattr_set, |
1076 | }; | |
1077 | ||
0c97be22 AG |
1078 | static const struct xattr_handler __maybe_unused |
1079 | ovl_posix_acl_default_xattr_handler = { | |
d837a49b MS |
1080 | .name = XATTR_NAME_POSIX_ACL_DEFAULT, |
1081 | .flags = ACL_TYPE_DEFAULT, | |
0eb45fc3 | 1082 | .get = ovl_posix_acl_xattr_get, |
d837a49b MS |
1083 | .set = ovl_posix_acl_xattr_set, |
1084 | }; | |
1085 | ||
1086 | static const struct xattr_handler ovl_own_xattr_handler = { | |
1087 | .prefix = OVL_XATTR_PREFIX, | |
0eb45fc3 | 1088 | .get = ovl_own_xattr_get, |
d837a49b MS |
1089 | .set = ovl_own_xattr_set, |
1090 | }; | |
1091 | ||
1092 | static const struct xattr_handler ovl_other_xattr_handler = { | |
1093 | .prefix = "", /* catch all */ | |
0eb45fc3 | 1094 | .get = ovl_other_xattr_get, |
d837a49b MS |
1095 | .set = ovl_other_xattr_set, |
1096 | }; | |
1097 | ||
1098 | static const struct xattr_handler *ovl_xattr_handlers[] = { | |
0c97be22 | 1099 | #ifdef CONFIG_FS_POSIX_ACL |
d837a49b MS |
1100 | &ovl_posix_acl_access_xattr_handler, |
1101 | &ovl_posix_acl_default_xattr_handler, | |
0c97be22 | 1102 | #endif |
d837a49b MS |
1103 | &ovl_own_xattr_handler, |
1104 | &ovl_other_xattr_handler, | |
1105 | NULL | |
1106 | }; | |
1107 | ||
e9be9d5e MS |
1108 | static int ovl_fill_super(struct super_block *sb, void *data, int silent) |
1109 | { | |
53a08cb9 MS |
1110 | struct path upperpath = { NULL, NULL }; |
1111 | struct path workpath = { NULL, NULL }; | |
e9be9d5e | 1112 | struct dentry *root_dentry; |
39b681f8 | 1113 | struct inode *realinode; |
e9be9d5e MS |
1114 | struct ovl_entry *oe; |
1115 | struct ovl_fs *ufs; | |
a78d9f0d MS |
1116 | struct path *stack = NULL; |
1117 | char *lowertmp; | |
1118 | char *lower; | |
1119 | unsigned int numlower; | |
1120 | unsigned int stacklen = 0; | |
dd662667 | 1121 | unsigned int i; |
7c03b5d4 | 1122 | bool remote = false; |
e9be9d5e MS |
1123 | int err; |
1124 | ||
f45827e8 EZ |
1125 | err = -ENOMEM; |
1126 | ufs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL); | |
1127 | if (!ufs) | |
e9be9d5e MS |
1128 | goto out; |
1129 | ||
f45827e8 EZ |
1130 | err = ovl_parse_opt((char *) data, &ufs->config); |
1131 | if (err) | |
1132 | goto out_free_config; | |
1133 | ||
e9be9d5e | 1134 | err = -EINVAL; |
53a08cb9 | 1135 | if (!ufs->config.lowerdir) { |
07f2af7b KK |
1136 | if (!silent) |
1137 | pr_err("overlayfs: missing 'lowerdir'\n"); | |
e9be9d5e MS |
1138 | goto out_free_config; |
1139 | } | |
1140 | ||
53a08cb9 | 1141 | sb->s_stack_depth = 0; |
cf9a6784 | 1142 | sb->s_maxbytes = MAX_LFS_FILESIZE; |
53a08cb9 | 1143 | if (ufs->config.upperdir) { |
53a08cb9 MS |
1144 | if (!ufs->config.workdir) { |
1145 | pr_err("overlayfs: missing 'workdir'\n"); | |
1146 | goto out_free_config; | |
1147 | } | |
e9be9d5e | 1148 | |
53a08cb9 MS |
1149 | err = ovl_mount_dir(ufs->config.upperdir, &upperpath); |
1150 | if (err) | |
1151 | goto out_free_config; | |
e9be9d5e | 1152 | |
71cbad7e | 1153 | /* Upper fs should not be r/o */ |
1154 | if (upperpath.mnt->mnt_sb->s_flags & MS_RDONLY) { | |
1155 | pr_err("overlayfs: upper fs is r/o, try multi-lower layers mount\n"); | |
1156 | err = -EINVAL; | |
1157 | goto out_put_upperpath; | |
1158 | } | |
1159 | ||
53a08cb9 MS |
1160 | err = ovl_mount_dir(ufs->config.workdir, &workpath); |
1161 | if (err) | |
1162 | goto out_put_upperpath; | |
1163 | ||
2f83fd8c | 1164 | err = -EINVAL; |
53a08cb9 MS |
1165 | if (upperpath.mnt != workpath.mnt) { |
1166 | pr_err("overlayfs: workdir and upperdir must reside under the same mount\n"); | |
1167 | goto out_put_workpath; | |
1168 | } | |
1169 | if (!ovl_workdir_ok(workpath.dentry, upperpath.dentry)) { | |
1170 | pr_err("overlayfs: workdir and upperdir must be separate subtrees\n"); | |
1171 | goto out_put_workpath; | |
1172 | } | |
1173 | sb->s_stack_depth = upperpath.mnt->mnt_sb->s_stack_depth; | |
cc259639 | 1174 | } |
a78d9f0d MS |
1175 | err = -ENOMEM; |
1176 | lowertmp = kstrdup(ufs->config.lowerdir, GFP_KERNEL); | |
1177 | if (!lowertmp) | |
ab508822 | 1178 | goto out_put_workpath; |
69c433ed | 1179 | |
a78d9f0d MS |
1180 | err = -EINVAL; |
1181 | stacklen = ovl_split_lowerdirs(lowertmp); | |
6be4506e | 1182 | if (stacklen > OVL_MAX_STACK) { |
fd36570a | 1183 | pr_err("overlayfs: too many lower directories, limit is %d\n", |
6be4506e | 1184 | OVL_MAX_STACK); |
a78d9f0d | 1185 | goto out_free_lowertmp; |
6be4506e | 1186 | } else if (!ufs->config.upperdir && stacklen == 1) { |
1187 | pr_err("overlayfs: at least 2 lowerdir are needed while upperdir nonexistent\n"); | |
1188 | goto out_free_lowertmp; | |
1189 | } | |
a78d9f0d MS |
1190 | |
1191 | stack = kcalloc(stacklen, sizeof(struct path), GFP_KERNEL); | |
1192 | if (!stack) | |
1193 | goto out_free_lowertmp; | |
1194 | ||
1195 | lower = lowertmp; | |
1196 | for (numlower = 0; numlower < stacklen; numlower++) { | |
1197 | err = ovl_lower_dir(lower, &stack[numlower], | |
7c03b5d4 MS |
1198 | &ufs->lower_namelen, &sb->s_stack_depth, |
1199 | &remote); | |
a78d9f0d MS |
1200 | if (err) |
1201 | goto out_put_lowerpath; | |
1202 | ||
1203 | lower = strchr(lower, '\0') + 1; | |
1204 | } | |
1205 | ||
69c433ed | 1206 | err = -EINVAL; |
ab508822 | 1207 | sb->s_stack_depth++; |
69c433ed MS |
1208 | if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) { |
1209 | pr_err("overlayfs: maximum fs stacking depth exceeded\n"); | |
3b7a9a24 | 1210 | goto out_put_lowerpath; |
69c433ed MS |
1211 | } |
1212 | ||
53a08cb9 MS |
1213 | if (ufs->config.upperdir) { |
1214 | ufs->upper_mnt = clone_private_mount(&upperpath); | |
1215 | err = PTR_ERR(ufs->upper_mnt); | |
1216 | if (IS_ERR(ufs->upper_mnt)) { | |
1217 | pr_err("overlayfs: failed to clone upperpath\n"); | |
1218 | goto out_put_lowerpath; | |
1219 | } | |
d719e8f2 MS |
1220 | /* Don't inherit atime flags */ |
1221 | ufs->upper_mnt->mnt_flags &= ~(MNT_NOATIME | MNT_NODIRATIME | MNT_RELATIME); | |
1222 | ||
1223 | sb->s_time_gran = ufs->upper_mnt->mnt_sb->s_time_gran; | |
3b7a9a24 | 1224 | |
53a08cb9 MS |
1225 | ufs->workdir = ovl_workdir_create(ufs->upper_mnt, workpath.dentry); |
1226 | err = PTR_ERR(ufs->workdir); | |
1227 | if (IS_ERR(ufs->workdir)) { | |
cc6f67bc MS |
1228 | pr_warn("overlayfs: failed to create directory %s/%s (errno: %i); mounting read-only\n", |
1229 | ufs->config.workdir, OVL_WORKDIR_NAME, -err); | |
1230 | sb->s_flags |= MS_RDONLY; | |
1231 | ufs->workdir = NULL; | |
53a08cb9 | 1232 | } |
45aebeaf VG |
1233 | |
1234 | /* | |
1235 | * Upper should support d_type, else whiteouts are visible. | |
1236 | * Given workdir and upper are on same fs, we can do | |
21765194 VG |
1237 | * iterate_dir() on workdir. This check requires successful |
1238 | * creation of workdir in previous step. | |
45aebeaf | 1239 | */ |
21765194 VG |
1240 | if (ufs->workdir) { |
1241 | err = ovl_check_d_type_supported(&workpath); | |
1242 | if (err < 0) | |
1243 | goto out_put_workdir; | |
45aebeaf | 1244 | |
e7c0b599 VG |
1245 | /* |
1246 | * We allowed this configuration and don't want to | |
1247 | * break users over kernel upgrade. So warn instead | |
1248 | * of erroring out. | |
1249 | */ | |
1250 | if (!err) | |
1251 | pr_warn("overlayfs: upper fs needs to support d_type.\n"); | |
45aebeaf | 1252 | } |
e9be9d5e MS |
1253 | } |
1254 | ||
2f83fd8c | 1255 | err = -ENOMEM; |
a78d9f0d | 1256 | ufs->lower_mnt = kcalloc(numlower, sizeof(struct vfsmount *), GFP_KERNEL); |
dd662667 | 1257 | if (ufs->lower_mnt == NULL) |
3b7a9a24 | 1258 | goto out_put_workdir; |
a78d9f0d MS |
1259 | for (i = 0; i < numlower; i++) { |
1260 | struct vfsmount *mnt = clone_private_mount(&stack[i]); | |
dd662667 | 1261 | |
2f83fd8c | 1262 | err = PTR_ERR(mnt); |
a78d9f0d MS |
1263 | if (IS_ERR(mnt)) { |
1264 | pr_err("overlayfs: failed to clone lowerpath\n"); | |
1265 | goto out_put_lower_mnt; | |
1266 | } | |
1267 | /* | |
1268 | * Make lower_mnt R/O. That way fchmod/fchown on lower file | |
1269 | * will fail instead of modifying lower fs. | |
1270 | */ | |
d719e8f2 | 1271 | mnt->mnt_flags |= MNT_READONLY | MNT_NOATIME; |
dd662667 | 1272 | |
a78d9f0d MS |
1273 | ufs->lower_mnt[ufs->numlower] = mnt; |
1274 | ufs->numlower++; | |
1275 | } | |
e9be9d5e | 1276 | |
71cbad7e | 1277 | /* If the upper fs is nonexistent, we mark overlayfs r/o too */ |
1278 | if (!ufs->upper_mnt) | |
e9be9d5e MS |
1279 | sb->s_flags |= MS_RDONLY; |
1280 | ||
7c03b5d4 MS |
1281 | if (remote) |
1282 | sb->s_d_op = &ovl_reval_dentry_operations; | |
1283 | else | |
1284 | sb->s_d_op = &ovl_dentry_operations; | |
e9be9d5e | 1285 | |
3fe6e52f AM |
1286 | ufs->creator_cred = prepare_creds(); |
1287 | if (!ufs->creator_cred) | |
1288 | goto out_put_lower_mnt; | |
1289 | ||
e9be9d5e | 1290 | err = -ENOMEM; |
a78d9f0d | 1291 | oe = ovl_alloc_entry(numlower); |
3b7a9a24 | 1292 | if (!oe) |
3fe6e52f | 1293 | goto out_put_cred; |
e9be9d5e | 1294 | |
39b681f8 | 1295 | root_dentry = d_make_root(ovl_new_inode(sb, S_IFDIR)); |
e9be9d5e | 1296 | if (!root_dentry) |
3b7a9a24 | 1297 | goto out_free_oe; |
e9be9d5e MS |
1298 | |
1299 | mntput(upperpath.mnt); | |
a78d9f0d MS |
1300 | for (i = 0; i < numlower; i++) |
1301 | mntput(stack[i].mnt); | |
e9be9d5e | 1302 | path_put(&workpath); |
a78d9f0d | 1303 | kfree(lowertmp); |
e9be9d5e MS |
1304 | |
1305 | oe->__upperdentry = upperpath.dentry; | |
a78d9f0d MS |
1306 | for (i = 0; i < numlower; i++) { |
1307 | oe->lowerstack[i].dentry = stack[i].dentry; | |
1308 | oe->lowerstack[i].mnt = ufs->lower_mnt[i]; | |
1309 | } | |
0f95502a | 1310 | kfree(stack); |
e9be9d5e MS |
1311 | |
1312 | root_dentry->d_fsdata = oe; | |
1313 | ||
39b681f8 MS |
1314 | realinode = d_inode(ovl_dentry_real(root_dentry)); |
1315 | ovl_inode_init(d_inode(root_dentry), realinode, !!upperpath.dentry); | |
1316 | ovl_copyattr(realinode, d_inode(root_dentry)); | |
ed06e069 | 1317 | |
cc259639 | 1318 | sb->s_magic = OVERLAYFS_SUPER_MAGIC; |
e9be9d5e | 1319 | sb->s_op = &ovl_super_operations; |
0c97be22 | 1320 | sb->s_xattr = ovl_xattr_handlers; |
e9be9d5e MS |
1321 | sb->s_root = root_dentry; |
1322 | sb->s_fs_info = ufs; | |
39a25b2b | 1323 | sb->s_flags |= MS_POSIXACL; |
e9be9d5e MS |
1324 | |
1325 | return 0; | |
1326 | ||
3b7a9a24 MS |
1327 | out_free_oe: |
1328 | kfree(oe); | |
3fe6e52f AM |
1329 | out_put_cred: |
1330 | put_cred(ufs->creator_cred); | |
e9be9d5e | 1331 | out_put_lower_mnt: |
dd662667 MS |
1332 | for (i = 0; i < ufs->numlower; i++) |
1333 | mntput(ufs->lower_mnt[i]); | |
1334 | kfree(ufs->lower_mnt); | |
3b7a9a24 MS |
1335 | out_put_workdir: |
1336 | dput(ufs->workdir); | |
e9be9d5e | 1337 | mntput(ufs->upper_mnt); |
e9be9d5e | 1338 | out_put_lowerpath: |
a78d9f0d MS |
1339 | for (i = 0; i < numlower; i++) |
1340 | path_put(&stack[i]); | |
1341 | kfree(stack); | |
1342 | out_free_lowertmp: | |
1343 | kfree(lowertmp); | |
3b7a9a24 MS |
1344 | out_put_workpath: |
1345 | path_put(&workpath); | |
e9be9d5e MS |
1346 | out_put_upperpath: |
1347 | path_put(&upperpath); | |
e9be9d5e | 1348 | out_free_config: |
f45827e8 EZ |
1349 | kfree(ufs->config.lowerdir); |
1350 | kfree(ufs->config.upperdir); | |
1351 | kfree(ufs->config.workdir); | |
1352 | kfree(ufs); | |
e9be9d5e MS |
1353 | out: |
1354 | return err; | |
1355 | } | |
1356 | ||
1357 | static struct dentry *ovl_mount(struct file_system_type *fs_type, int flags, | |
1358 | const char *dev_name, void *raw_data) | |
1359 | { | |
1360 | return mount_nodev(fs_type, flags, raw_data, ovl_fill_super); | |
1361 | } | |
1362 | ||
1363 | static struct file_system_type ovl_fs_type = { | |
1364 | .owner = THIS_MODULE, | |
ef94b186 | 1365 | .name = "overlay", |
e9be9d5e MS |
1366 | .mount = ovl_mount, |
1367 | .kill_sb = kill_anon_super, | |
1368 | }; | |
ef94b186 | 1369 | MODULE_ALIAS_FS("overlay"); |
e9be9d5e MS |
1370 | |
1371 | static int __init ovl_init(void) | |
1372 | { | |
1373 | return register_filesystem(&ovl_fs_type); | |
1374 | } | |
1375 | ||
1376 | static void __exit ovl_exit(void) | |
1377 | { | |
1378 | unregister_filesystem(&ovl_fs_type); | |
1379 | } | |
1380 | ||
1381 | module_init(ovl_init); | |
1382 | module_exit(ovl_exit); |