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> | |
5b825c3a | 11 | #include <linux/cred.h> |
bbb1e54d MS |
12 | #include <linux/namei.h> |
13 | #include <linux/xattr.h> | |
02b69b28 | 14 | #include <linux/ratelimit.h> |
a9d01957 AG |
15 | #include <linux/mount.h> |
16 | #include <linux/exportfs.h> | |
bbb1e54d MS |
17 | #include "overlayfs.h" |
18 | #include "ovl_entry.h" | |
19 | ||
e28edc46 MS |
20 | struct ovl_lookup_data { |
21 | struct qstr name; | |
22 | bool is_dir; | |
23 | bool opaque; | |
24 | bool stop; | |
25 | bool last; | |
02b69b28 | 26 | char *redirect; |
e28edc46 | 27 | }; |
bbb1e54d | 28 | |
02b69b28 MS |
29 | static int ovl_check_redirect(struct dentry *dentry, struct ovl_lookup_data *d, |
30 | size_t prelen, const char *post) | |
31 | { | |
32 | int res; | |
33 | char *s, *next, *buf = NULL; | |
34 | ||
35 | res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, NULL, 0); | |
36 | if (res < 0) { | |
37 | if (res == -ENODATA || res == -EOPNOTSUPP) | |
38 | return 0; | |
39 | goto fail; | |
40 | } | |
41 | buf = kzalloc(prelen + res + strlen(post) + 1, GFP_TEMPORARY); | |
42 | if (!buf) | |
43 | return -ENOMEM; | |
44 | ||
45 | if (res == 0) | |
46 | goto invalid; | |
47 | ||
48 | res = vfs_getxattr(dentry, OVL_XATTR_REDIRECT, buf, res); | |
49 | if (res < 0) | |
50 | goto fail; | |
51 | if (res == 0) | |
52 | goto invalid; | |
53 | if (buf[0] == '/') { | |
54 | for (s = buf; *s++ == '/'; s = next) { | |
55 | next = strchrnul(s, '/'); | |
56 | if (s == next) | |
57 | goto invalid; | |
58 | } | |
59 | } else { | |
60 | if (strchr(buf, '/') != NULL) | |
61 | goto invalid; | |
62 | ||
63 | memmove(buf + prelen, buf, res); | |
64 | memcpy(buf, d->name.name, prelen); | |
65 | } | |
66 | ||
67 | strcat(buf, post); | |
68 | kfree(d->redirect); | |
69 | d->redirect = buf; | |
70 | d->name.name = d->redirect; | |
71 | d->name.len = strlen(d->redirect); | |
72 | ||
73 | return 0; | |
74 | ||
75 | err_free: | |
76 | kfree(buf); | |
77 | return 0; | |
78 | fail: | |
79 | pr_warn_ratelimited("overlayfs: failed to get redirect (%i)\n", res); | |
80 | goto err_free; | |
81 | invalid: | |
82 | pr_warn_ratelimited("overlayfs: invalid redirect (%s)\n", buf); | |
83 | goto err_free; | |
84 | } | |
85 | ||
a9d01957 AG |
86 | static int ovl_acceptable(void *ctx, struct dentry *dentry) |
87 | { | |
88 | return 1; | |
89 | } | |
90 | ||
8b88a2e6 | 91 | static struct ovl_fh *ovl_get_origin_fh(struct dentry *dentry) |
a9d01957 AG |
92 | { |
93 | int res; | |
94 | struct ovl_fh *fh = NULL; | |
a9d01957 AG |
95 | |
96 | res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, NULL, 0); | |
97 | if (res < 0) { | |
98 | if (res == -ENODATA || res == -EOPNOTSUPP) | |
99 | return NULL; | |
100 | goto fail; | |
101 | } | |
102 | /* Zero size value means "copied up but origin unknown" */ | |
103 | if (res == 0) | |
104 | return NULL; | |
105 | ||
8b88a2e6 | 106 | fh = kzalloc(res, GFP_TEMPORARY); |
a9d01957 AG |
107 | if (!fh) |
108 | return ERR_PTR(-ENOMEM); | |
109 | ||
110 | res = vfs_getxattr(dentry, OVL_XATTR_ORIGIN, fh, res); | |
111 | if (res < 0) | |
112 | goto fail; | |
113 | ||
114 | if (res < sizeof(struct ovl_fh) || res < fh->len) | |
115 | goto invalid; | |
116 | ||
117 | if (fh->magic != OVL_FH_MAGIC) | |
118 | goto invalid; | |
119 | ||
120 | /* Treat larger version and unknown flags as "origin unknown" */ | |
121 | if (fh->version > OVL_FH_VERSION || fh->flags & ~OVL_FH_FLAG_ALL) | |
122 | goto out; | |
123 | ||
124 | /* Treat endianness mismatch as "origin unknown" */ | |
125 | if (!(fh->flags & OVL_FH_FLAG_ANY_ENDIAN) && | |
126 | (fh->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN) | |
127 | goto out; | |
128 | ||
8b88a2e6 AG |
129 | return fh; |
130 | ||
131 | out: | |
132 | kfree(fh); | |
133 | return NULL; | |
134 | ||
135 | fail: | |
136 | pr_warn_ratelimited("overlayfs: failed to get origin (%i)\n", res); | |
137 | goto out; | |
138 | invalid: | |
139 | pr_warn_ratelimited("overlayfs: invalid origin (%*phN)\n", res, fh); | |
140 | goto out; | |
141 | } | |
142 | ||
143 | static struct dentry *ovl_get_origin(struct dentry *dentry, | |
144 | struct vfsmount *mnt) | |
145 | { | |
146 | struct dentry *origin = NULL; | |
147 | struct ovl_fh *fh = ovl_get_origin_fh(dentry); | |
148 | int bytes; | |
149 | ||
150 | if (IS_ERR_OR_NULL(fh)) | |
151 | return (struct dentry *)fh; | |
a9d01957 AG |
152 | |
153 | /* | |
154 | * Make sure that the stored uuid matches the uuid of the lower | |
155 | * layer where file handle will be decoded. | |
156 | */ | |
85787090 | 157 | if (!uuid_equal(&fh->uuid, &mnt->mnt_sb->s_uuid)) |
a9d01957 AG |
158 | goto out; |
159 | ||
8b88a2e6 | 160 | bytes = (fh->len - offsetof(struct ovl_fh, fid)); |
a9d01957 AG |
161 | origin = exportfs_decode_fh(mnt, (struct fid *)fh->fid, |
162 | bytes >> 2, (int)fh->type, | |
163 | ovl_acceptable, NULL); | |
164 | if (IS_ERR(origin)) { | |
165 | /* Treat stale file handle as "origin unknown" */ | |
166 | if (origin == ERR_PTR(-ESTALE)) | |
167 | origin = NULL; | |
168 | goto out; | |
169 | } | |
170 | ||
171 | if (ovl_dentry_weird(origin) || | |
8b88a2e6 | 172 | ((d_inode(origin)->i_mode ^ d_inode(dentry)->i_mode) & S_IFMT)) |
a9d01957 | 173 | goto invalid; |
a9d01957 AG |
174 | |
175 | out: | |
176 | kfree(fh); | |
177 | return origin; | |
178 | ||
a9d01957 | 179 | invalid: |
8b88a2e6 AG |
180 | pr_warn_ratelimited("overlayfs: invalid origin (%pd2)\n", origin); |
181 | dput(origin); | |
182 | origin = NULL; | |
a9d01957 AG |
183 | goto out; |
184 | } | |
185 | ||
ee1d6d37 AG |
186 | static bool ovl_is_opaquedir(struct dentry *dentry) |
187 | { | |
188 | return ovl_check_dir_xattr(dentry, OVL_XATTR_OPAQUE); | |
189 | } | |
190 | ||
e28edc46 MS |
191 | static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d, |
192 | const char *name, unsigned int namelen, | |
02b69b28 | 193 | size_t prelen, const char *post, |
e28edc46 MS |
194 | struct dentry **ret) |
195 | { | |
196 | struct dentry *this; | |
197 | int err; | |
198 | ||
199 | this = lookup_one_len_unlocked(name, base, namelen); | |
200 | if (IS_ERR(this)) { | |
201 | err = PTR_ERR(this); | |
202 | this = NULL; | |
203 | if (err == -ENOENT || err == -ENAMETOOLONG) | |
204 | goto out; | |
205 | goto out_err; | |
206 | } | |
207 | if (!this->d_inode) | |
208 | goto put_and_out; | |
209 | ||
210 | if (ovl_dentry_weird(this)) { | |
211 | /* Don't support traversing automounts and other weirdness */ | |
212 | err = -EREMOTE; | |
213 | goto out_err; | |
214 | } | |
215 | if (ovl_is_whiteout(this)) { | |
216 | d->stop = d->opaque = true; | |
217 | goto put_and_out; | |
218 | } | |
219 | if (!d_can_lookup(this)) { | |
220 | d->stop = true; | |
221 | if (d->is_dir) | |
222 | goto put_and_out; | |
223 | goto out; | |
224 | } | |
225 | d->is_dir = true; | |
226 | if (!d->last && ovl_is_opaquedir(this)) { | |
227 | d->stop = d->opaque = true; | |
228 | goto out; | |
229 | } | |
02b69b28 MS |
230 | err = ovl_check_redirect(this, d, prelen, post); |
231 | if (err) | |
232 | goto out_err; | |
e28edc46 MS |
233 | out: |
234 | *ret = this; | |
235 | return 0; | |
236 | ||
237 | put_and_out: | |
238 | dput(this); | |
239 | this = NULL; | |
240 | goto out; | |
241 | ||
242 | out_err: | |
243 | dput(this); | |
244 | return err; | |
245 | } | |
246 | ||
247 | static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, | |
248 | struct dentry **ret) | |
249 | { | |
4c7d0c9c AG |
250 | /* Counting down from the end, since the prefix can change */ |
251 | size_t rem = d->name.len - 1; | |
02b69b28 MS |
252 | struct dentry *dentry = NULL; |
253 | int err; | |
254 | ||
4c7d0c9c | 255 | if (d->name.name[0] != '/') |
02b69b28 MS |
256 | return ovl_lookup_single(base, d, d->name.name, d->name.len, |
257 | 0, "", ret); | |
258 | ||
4c7d0c9c AG |
259 | while (!IS_ERR_OR_NULL(base) && d_can_lookup(base)) { |
260 | const char *s = d->name.name + d->name.len - rem; | |
02b69b28 | 261 | const char *next = strchrnul(s, '/'); |
4c7d0c9c AG |
262 | size_t thislen = next - s; |
263 | bool end = !next[0]; | |
02b69b28 | 264 | |
4c7d0c9c AG |
265 | /* Verify we did not go off the rails */ |
266 | if (WARN_ON(s[-1] != '/')) | |
02b69b28 MS |
267 | return -EIO; |
268 | ||
4c7d0c9c AG |
269 | err = ovl_lookup_single(base, d, s, thislen, |
270 | d->name.len - rem, next, &base); | |
02b69b28 MS |
271 | dput(dentry); |
272 | if (err) | |
273 | return err; | |
274 | dentry = base; | |
4c7d0c9c AG |
275 | if (end) |
276 | break; | |
277 | ||
278 | rem -= thislen + 1; | |
279 | ||
280 | if (WARN_ON(rem >= d->name.len)) | |
281 | return -EIO; | |
02b69b28 MS |
282 | } |
283 | *ret = dentry; | |
284 | return 0; | |
e28edc46 MS |
285 | } |
286 | ||
a9d01957 | 287 | |
415543d5 AG |
288 | static int ovl_check_origin(struct dentry *upperdentry, |
289 | struct path *lowerstack, unsigned int numlower, | |
a9d01957 AG |
290 | struct path **stackp, unsigned int *ctrp) |
291 | { | |
a9d01957 | 292 | struct vfsmount *mnt; |
f7d3daca AG |
293 | struct dentry *origin = NULL; |
294 | int i; | |
a9d01957 | 295 | |
a9d01957 | 296 | |
415543d5 AG |
297 | for (i = 0; i < numlower; i++) { |
298 | mnt = lowerstack[i].mnt; | |
f7d3daca AG |
299 | origin = ovl_get_origin(upperdentry, mnt); |
300 | if (IS_ERR(origin)) | |
301 | return PTR_ERR(origin); | |
302 | ||
303 | if (origin) | |
304 | break; | |
305 | } | |
306 | ||
307 | if (!origin) | |
308 | return 0; | |
a9d01957 | 309 | |
415543d5 AG |
310 | BUG_ON(*ctrp); |
311 | if (!*stackp) | |
312 | *stackp = kmalloc(sizeof(struct path), GFP_TEMPORARY); | |
a9d01957 AG |
313 | if (!*stackp) { |
314 | dput(origin); | |
315 | return -ENOMEM; | |
316 | } | |
317 | **stackp = (struct path) { .dentry = origin, .mnt = mnt }; | |
318 | *ctrp = 1; | |
319 | ||
320 | return 0; | |
321 | } | |
322 | ||
8b88a2e6 AG |
323 | /* |
324 | * Verify that @fh matches the origin file handle stored in OVL_XATTR_ORIGIN. | |
325 | * Return 0 on match, -ESTALE on mismatch, < 0 on error. | |
326 | */ | |
327 | static int ovl_verify_origin_fh(struct dentry *dentry, const struct ovl_fh *fh) | |
328 | { | |
329 | struct ovl_fh *ofh = ovl_get_origin_fh(dentry); | |
330 | int err = 0; | |
331 | ||
332 | if (!ofh) | |
333 | return -ENODATA; | |
334 | ||
335 | if (IS_ERR(ofh)) | |
336 | return PTR_ERR(ofh); | |
337 | ||
338 | if (fh->len != ofh->len || memcmp(fh, ofh, fh->len)) | |
339 | err = -ESTALE; | |
340 | ||
341 | kfree(ofh); | |
342 | return err; | |
343 | } | |
344 | ||
345 | /* | |
346 | * Verify that an inode matches the origin file handle stored in upper inode. | |
347 | * | |
348 | * If @set is true and there is no stored file handle, encode and store origin | |
349 | * file handle in OVL_XATTR_ORIGIN. | |
350 | * | |
351 | * Return 0 on match, -ESTALE on mismatch, < 0 on error. | |
352 | */ | |
353 | int ovl_verify_origin(struct dentry *dentry, struct vfsmount *mnt, | |
54fb347e | 354 | struct dentry *origin, bool is_upper, bool set) |
8b88a2e6 AG |
355 | { |
356 | struct inode *inode; | |
357 | struct ovl_fh *fh; | |
358 | int err; | |
359 | ||
54fb347e | 360 | fh = ovl_encode_fh(origin, is_upper); |
8b88a2e6 AG |
361 | err = PTR_ERR(fh); |
362 | if (IS_ERR(fh)) | |
363 | goto fail; | |
364 | ||
365 | err = ovl_verify_origin_fh(dentry, fh); | |
366 | if (set && err == -ENODATA) | |
367 | err = ovl_do_setxattr(dentry, OVL_XATTR_ORIGIN, fh, fh->len, 0); | |
368 | if (err) | |
369 | goto fail; | |
370 | ||
371 | out: | |
372 | kfree(fh); | |
373 | return err; | |
374 | ||
375 | fail: | |
376 | inode = d_inode(origin); | |
377 | pr_warn_ratelimited("overlayfs: failed to verify origin (%pd2, ino=%lu, err=%i)\n", | |
378 | origin, inode ? inode->i_ino : 0, err); | |
379 | goto out; | |
380 | } | |
381 | ||
415543d5 AG |
382 | /* |
383 | * Verify that an index entry name matches the origin file handle stored in | |
384 | * OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path. | |
385 | * Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error. | |
386 | */ | |
387 | int ovl_verify_index(struct dentry *index, struct path *lowerstack, | |
388 | unsigned int numlower) | |
389 | { | |
390 | struct ovl_fh *fh = NULL; | |
391 | size_t len; | |
392 | struct path origin = { }; | |
393 | struct path *stack = &origin; | |
394 | unsigned int ctr = 0; | |
395 | int err; | |
396 | ||
397 | if (!d_inode(index)) | |
398 | return 0; | |
399 | ||
61b67471 AG |
400 | /* |
401 | * Directory index entries are going to be used for looking up | |
402 | * redirected upper dirs by lower dir fh when decoding an overlay | |
403 | * file handle of a merge dir. Whiteout index entries are going to be | |
404 | * used as an indication that an exported overlay file handle should | |
405 | * be treated as stale (i.e. after unlink of the overlay inode). | |
406 | * We don't know the verification rules for directory and whiteout | |
407 | * index entries, because they have not been implemented yet, so return | |
408 | * EROFS if those entries are found to avoid corrupting an index that | |
409 | * was created by a newer kernel. | |
410 | */ | |
411 | err = -EROFS; | |
412 | if (d_is_dir(index) || ovl_is_whiteout(index)) | |
415543d5 AG |
413 | goto fail; |
414 | ||
415 | err = -EINVAL; | |
416 | if (index->d_name.len < sizeof(struct ovl_fh)*2) | |
417 | goto fail; | |
418 | ||
419 | err = -ENOMEM; | |
420 | len = index->d_name.len / 2; | |
421 | fh = kzalloc(len, GFP_TEMPORARY); | |
422 | if (!fh) | |
423 | goto fail; | |
424 | ||
425 | err = -EINVAL; | |
426 | if (hex2bin((u8 *)fh, index->d_name.name, len) || len != fh->len) | |
427 | goto fail; | |
428 | ||
429 | err = ovl_verify_origin_fh(index, fh); | |
430 | if (err) | |
431 | goto fail; | |
432 | ||
433 | err = ovl_check_origin(index, lowerstack, numlower, &stack, &ctr); | |
434 | if (!err && !ctr) | |
435 | err = -ESTALE; | |
436 | if (err) | |
437 | goto fail; | |
438 | ||
caf70cb2 AG |
439 | /* Check if index is orphan and don't warn before cleaning it */ |
440 | if (d_inode(index)->i_nlink == 1 && | |
441 | ovl_get_nlink(index, origin.dentry, 0) == 0) | |
442 | err = -ENOENT; | |
443 | ||
415543d5 AG |
444 | dput(origin.dentry); |
445 | out: | |
446 | kfree(fh); | |
447 | return err; | |
448 | ||
449 | fail: | |
61b67471 AG |
450 | pr_warn_ratelimited("overlayfs: failed to verify index (%pd2, ftype=%x, err=%i)\n", |
451 | index, d_inode(index)->i_mode & S_IFMT, err); | |
415543d5 AG |
452 | goto out; |
453 | } | |
454 | ||
359f392c AG |
455 | /* |
456 | * Lookup in indexdir for the index entry of a lower real inode or a copy up | |
457 | * origin inode. The index entry name is the hex representation of the lower | |
458 | * inode file handle. | |
459 | * | |
460 | * If the index dentry in negative, then either no lower aliases have been | |
461 | * copied up yet, or aliases have been copied up in older kernels and are | |
462 | * not indexed. | |
463 | * | |
464 | * If the index dentry for a copy up origin inode is positive, but points | |
465 | * to an inode different than the upper inode, then either the upper inode | |
466 | * has been copied up and not indexed or it was indexed, but since then | |
467 | * index dir was cleared. Either way, that index cannot be used to indentify | |
468 | * the overlay inode. | |
469 | */ | |
470 | int ovl_get_index_name(struct dentry *origin, struct qstr *name) | |
471 | { | |
472 | int err; | |
473 | struct ovl_fh *fh; | |
474 | char *n, *s; | |
475 | ||
476 | fh = ovl_encode_fh(origin, false); | |
477 | if (IS_ERR(fh)) | |
478 | return PTR_ERR(fh); | |
479 | ||
480 | err = -ENOMEM; | |
481 | n = kzalloc(fh->len * 2, GFP_TEMPORARY); | |
482 | if (n) { | |
483 | s = bin2hex(n, fh, fh->len); | |
484 | *name = (struct qstr) QSTR_INIT(n, s - n); | |
485 | err = 0; | |
486 | } | |
487 | kfree(fh); | |
488 | ||
489 | return err; | |
490 | ||
491 | } | |
492 | ||
493 | static struct dentry *ovl_lookup_index(struct dentry *dentry, | |
494 | struct dentry *upper, | |
495 | struct dentry *origin) | |
496 | { | |
497 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; | |
498 | struct dentry *index; | |
499 | struct inode *inode; | |
500 | struct qstr name; | |
501 | int err; | |
502 | ||
503 | err = ovl_get_index_name(origin, &name); | |
504 | if (err) | |
505 | return ERR_PTR(err); | |
506 | ||
507 | index = lookup_one_len_unlocked(name.name, ofs->indexdir, name.len); | |
508 | if (IS_ERR(index)) { | |
509 | pr_warn_ratelimited("overlayfs: failed inode index lookup (ino=%lu, key=%*s, err=%i);\n" | |
510 | "overlayfs: mount with '-o index=off' to disable inodes index.\n", | |
511 | d_inode(origin)->i_ino, name.len, name.name, | |
512 | err); | |
513 | goto out; | |
514 | } | |
515 | ||
0e082555 | 516 | inode = d_inode(index); |
359f392c AG |
517 | if (d_is_negative(index)) { |
518 | if (upper && d_inode(origin)->i_nlink > 1) { | |
519 | pr_warn_ratelimited("overlayfs: hard link with origin but no index (ino=%lu).\n", | |
520 | d_inode(origin)->i_ino); | |
521 | goto fail; | |
522 | } | |
523 | ||
524 | dput(index); | |
525 | index = NULL; | |
0e082555 AG |
526 | } else if (upper && d_inode(upper) != inode) { |
527 | pr_warn_ratelimited("overlayfs: wrong index found (index=%pd2, ino=%lu, upper ino=%lu).\n", | |
528 | index, inode->i_ino, d_inode(upper)->i_ino); | |
529 | goto fail; | |
530 | } else if (ovl_dentry_weird(index) || ovl_is_whiteout(index) || | |
531 | ((inode->i_mode ^ d_inode(origin)->i_mode) & S_IFMT)) { | |
532 | /* | |
533 | * Index should always be of the same file type as origin | |
534 | * except for the case of a whiteout index. A whiteout | |
535 | * index should only exist if all lower aliases have been | |
536 | * unlinked, which means that finding a lower origin on lookup | |
537 | * whose index is a whiteout should be treated as an error. | |
538 | */ | |
539 | pr_warn_ratelimited("overlayfs: bad index found (index=%pd2, ftype=%x, origin ftype=%x).\n", | |
540 | index, d_inode(index)->i_mode & S_IFMT, | |
541 | d_inode(origin)->i_mode & S_IFMT); | |
359f392c AG |
542 | goto fail; |
543 | } | |
544 | ||
545 | out: | |
546 | kfree(name.name); | |
547 | return index; | |
548 | ||
549 | fail: | |
550 | dput(index); | |
551 | index = ERR_PTR(-EIO); | |
552 | goto out; | |
553 | } | |
554 | ||
bbb1e54d MS |
555 | /* |
556 | * Returns next layer in stack starting from top. | |
557 | * Returns -1 if this is the last layer. | |
558 | */ | |
559 | int ovl_path_next(int idx, struct dentry *dentry, struct path *path) | |
560 | { | |
561 | struct ovl_entry *oe = dentry->d_fsdata; | |
562 | ||
563 | BUG_ON(idx < 0); | |
564 | if (idx == 0) { | |
565 | ovl_path_upper(dentry, path); | |
566 | if (path->dentry) | |
567 | return oe->numlower ? 1 : -1; | |
568 | idx++; | |
569 | } | |
570 | BUG_ON(idx > oe->numlower); | |
571 | *path = oe->lowerstack[idx - 1]; | |
572 | ||
573 | return (idx < oe->numlower) ? idx + 1 : -1; | |
574 | } | |
575 | ||
576 | struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, | |
577 | unsigned int flags) | |
578 | { | |
579 | struct ovl_entry *oe; | |
580 | const struct cred *old_cred; | |
6b2d5fe4 | 581 | struct ovl_fs *ofs = dentry->d_sb->s_fs_info; |
bbb1e54d | 582 | struct ovl_entry *poe = dentry->d_parent->d_fsdata; |
c22205d0 | 583 | struct ovl_entry *roe = dentry->d_sb->s_root->d_fsdata; |
bbb1e54d MS |
584 | struct path *stack = NULL; |
585 | struct dentry *upperdir, *upperdentry = NULL; | |
359f392c | 586 | struct dentry *index = NULL; |
bbb1e54d MS |
587 | unsigned int ctr = 0; |
588 | struct inode *inode = NULL; | |
589 | bool upperopaque = false; | |
02b69b28 | 590 | char *upperredirect = NULL; |
bbb1e54d MS |
591 | struct dentry *this; |
592 | unsigned int i; | |
593 | int err; | |
e28edc46 MS |
594 | struct ovl_lookup_data d = { |
595 | .name = dentry->d_name, | |
596 | .is_dir = false, | |
597 | .opaque = false, | |
598 | .stop = false, | |
599 | .last = !poe->numlower, | |
02b69b28 | 600 | .redirect = NULL, |
e28edc46 | 601 | }; |
bbb1e54d | 602 | |
6b2d5fe4 MS |
603 | if (dentry->d_name.len > ofs->namelen) |
604 | return ERR_PTR(-ENAMETOOLONG); | |
605 | ||
bbb1e54d | 606 | old_cred = ovl_override_creds(dentry->d_sb); |
09d8b586 | 607 | upperdir = ovl_dentry_upper(dentry->d_parent); |
bbb1e54d | 608 | if (upperdir) { |
e28edc46 MS |
609 | err = ovl_lookup_layer(upperdir, &d, &upperdentry); |
610 | if (err) | |
bbb1e54d MS |
611 | goto out; |
612 | ||
e28edc46 MS |
613 | if (upperdentry && unlikely(ovl_dentry_remote(upperdentry))) { |
614 | dput(upperdentry); | |
615 | err = -EREMOTE; | |
616 | goto out; | |
bbb1e54d | 617 | } |
a9d01957 AG |
618 | if (upperdentry && !d.is_dir) { |
619 | BUG_ON(!d.stop || d.redirect); | |
f7d3daca AG |
620 | /* |
621 | * Lookup copy up origin by decoding origin file handle. | |
622 | * We may get a disconnected dentry, which is fine, | |
623 | * because we only need to hold the origin inode in | |
624 | * cache and use its inode number. We may even get a | |
625 | * connected dentry, that is not under any of the lower | |
626 | * layers root. That is also fine for using it's inode | |
627 | * number - it's the same as if we held a reference | |
628 | * to a dentry in lower layer that was moved under us. | |
629 | */ | |
415543d5 AG |
630 | err = ovl_check_origin(upperdentry, roe->lowerstack, |
631 | roe->numlower, &stack, &ctr); | |
a9d01957 AG |
632 | if (err) |
633 | goto out; | |
634 | } | |
02b69b28 MS |
635 | |
636 | if (d.redirect) { | |
637 | upperredirect = kstrdup(d.redirect, GFP_KERNEL); | |
638 | if (!upperredirect) | |
639 | goto out_put_upper; | |
640 | if (d.redirect[0] == '/') | |
c22205d0 | 641 | poe = roe; |
02b69b28 | 642 | } |
e28edc46 | 643 | upperopaque = d.opaque; |
bbb1e54d MS |
644 | } |
645 | ||
e28edc46 | 646 | if (!d.stop && poe->numlower) { |
bbb1e54d | 647 | err = -ENOMEM; |
02b69b28 | 648 | stack = kcalloc(ofs->numlower, sizeof(struct path), |
e28edc46 | 649 | GFP_TEMPORARY); |
bbb1e54d MS |
650 | if (!stack) |
651 | goto out_put_upper; | |
652 | } | |
653 | ||
e28edc46 | 654 | for (i = 0; !d.stop && i < poe->numlower; i++) { |
bbb1e54d MS |
655 | struct path lowerpath = poe->lowerstack[i]; |
656 | ||
e28edc46 MS |
657 | d.last = i == poe->numlower - 1; |
658 | err = ovl_lookup_layer(lowerpath.dentry, &d, &this); | |
659 | if (err) | |
bbb1e54d | 660 | goto out_put; |
6b2d5fe4 | 661 | |
bbb1e54d MS |
662 | if (!this) |
663 | continue; | |
bbb1e54d MS |
664 | |
665 | stack[ctr].dentry = this; | |
666 | stack[ctr].mnt = lowerpath.mnt; | |
667 | ctr++; | |
02b69b28 MS |
668 | |
669 | if (d.stop) | |
670 | break; | |
671 | ||
c22205d0 AG |
672 | if (d.redirect && d.redirect[0] == '/' && poe != roe) { |
673 | poe = roe; | |
02b69b28 MS |
674 | |
675 | /* Find the current layer on the root dentry */ | |
676 | for (i = 0; i < poe->numlower; i++) | |
677 | if (poe->lowerstack[i].mnt == lowerpath.mnt) | |
678 | break; | |
679 | if (WARN_ON(i == poe->numlower)) | |
680 | break; | |
681 | } | |
bbb1e54d MS |
682 | } |
683 | ||
359f392c AG |
684 | /* Lookup index by lower inode and verify it matches upper inode */ |
685 | if (ctr && !d.is_dir && ovl_indexdir(dentry->d_sb)) { | |
686 | struct dentry *origin = stack[0].dentry; | |
687 | ||
688 | index = ovl_lookup_index(dentry, upperdentry, origin); | |
689 | if (IS_ERR(index)) { | |
690 | err = PTR_ERR(index); | |
691 | index = NULL; | |
692 | goto out_put; | |
693 | } | |
694 | } | |
695 | ||
bbb1e54d MS |
696 | oe = ovl_alloc_entry(ctr); |
697 | err = -ENOMEM; | |
698 | if (!oe) | |
699 | goto out_put; | |
700 | ||
e6d2ebdd | 701 | oe->opaque = upperopaque; |
e6d2ebdd MS |
702 | memcpy(oe->lowerstack, stack, sizeof(struct path) * ctr); |
703 | dentry->d_fsdata = oe; | |
bbb1e54d | 704 | |
55acc661 MS |
705 | if (upperdentry) |
706 | ovl_dentry_set_upper_alias(dentry); | |
707 | else if (index) | |
359f392c AG |
708 | upperdentry = dget(index); |
709 | ||
e6d2ebdd | 710 | if (upperdentry || ctr) { |
09d8b586 | 711 | inode = ovl_get_inode(dentry, upperdentry); |
b9ac5c27 MS |
712 | err = PTR_ERR(inode); |
713 | if (IS_ERR(inode)) | |
bbb1e54d | 714 | goto out_free_oe; |
cf31c463 MS |
715 | |
716 | OVL_I(inode)->redirect = upperredirect; | |
359f392c AG |
717 | if (index) |
718 | ovl_set_flag(OVL_INDEX, inode); | |
bbb1e54d MS |
719 | } |
720 | ||
721 | revert_creds(old_cred); | |
359f392c | 722 | dput(index); |
bbb1e54d | 723 | kfree(stack); |
02b69b28 | 724 | kfree(d.redirect); |
bbb1e54d MS |
725 | d_add(dentry, inode); |
726 | ||
727 | return NULL; | |
728 | ||
729 | out_free_oe: | |
e6d2ebdd | 730 | dentry->d_fsdata = NULL; |
bbb1e54d MS |
731 | kfree(oe); |
732 | out_put: | |
359f392c | 733 | dput(index); |
bbb1e54d MS |
734 | for (i = 0; i < ctr; i++) |
735 | dput(stack[i].dentry); | |
736 | kfree(stack); | |
737 | out_put_upper: | |
738 | dput(upperdentry); | |
02b69b28 | 739 | kfree(upperredirect); |
bbb1e54d | 740 | out: |
02b69b28 | 741 | kfree(d.redirect); |
bbb1e54d MS |
742 | revert_creds(old_cred); |
743 | return ERR_PTR(err); | |
744 | } | |
745 | ||
746 | bool ovl_lower_positive(struct dentry *dentry) | |
747 | { | |
748 | struct ovl_entry *oe = dentry->d_fsdata; | |
749 | struct ovl_entry *poe = dentry->d_parent->d_fsdata; | |
750 | const struct qstr *name = &dentry->d_name; | |
751 | unsigned int i; | |
752 | bool positive = false; | |
753 | bool done = false; | |
754 | ||
755 | /* | |
756 | * If dentry is negative, then lower is positive iff this is a | |
757 | * whiteout. | |
758 | */ | |
759 | if (!dentry->d_inode) | |
760 | return oe->opaque; | |
761 | ||
762 | /* Negative upper -> positive lower */ | |
09d8b586 | 763 | if (!ovl_dentry_upper(dentry)) |
bbb1e54d MS |
764 | return true; |
765 | ||
766 | /* Positive upper -> have to look up lower to see whether it exists */ | |
767 | for (i = 0; !done && !positive && i < poe->numlower; i++) { | |
768 | struct dentry *this; | |
769 | struct dentry *lowerdir = poe->lowerstack[i].dentry; | |
770 | ||
771 | this = lookup_one_len_unlocked(name->name, lowerdir, | |
772 | name->len); | |
773 | if (IS_ERR(this)) { | |
774 | switch (PTR_ERR(this)) { | |
775 | case -ENOENT: | |
776 | case -ENAMETOOLONG: | |
777 | break; | |
778 | ||
779 | default: | |
780 | /* | |
781 | * Assume something is there, we just couldn't | |
782 | * access it. | |
783 | */ | |
784 | positive = true; | |
785 | break; | |
786 | } | |
787 | } else { | |
788 | if (this->d_inode) { | |
789 | positive = !ovl_is_whiteout(this); | |
790 | done = true; | |
791 | } | |
792 | dput(this); | |
793 | } | |
794 | } | |
795 | ||
796 | return positive; | |
797 | } |