1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * Copyright (C) 2011 Novell Inc. |
4 | * Copyright (C) 2016 Red Hat, Inc. |
5 | */ |
6 | |
7 | #include <linux/fs.h> |
8 | #include <linux/cred.h> |
9 | #include <linux/ctype.h> |
10 | #include <linux/namei.h> |
11 | #include <linux/xattr.h> |
12 | #include <linux/ratelimit.h> |
13 | #include <linux/mount.h> |
14 | #include <linux/exportfs.h> |
15 | #include "overlayfs.h" |
16 | |
17 | #include "../internal.h" /* for vfs_path_lookup */ |
18 | |
19 | struct ovl_lookup_data { |
20 | struct super_block *sb; |
21 | struct vfsmount *mnt; |
22 | struct qstr name; |
23 | bool is_dir; |
24 | bool opaque; |
25 | bool stop; |
26 | bool last; |
27 | char *redirect; |
28 | int metacopy; |
29 | /* Referring to last redirect xattr */ |
30 | bool absolute_redirect; |
31 | }; |
32 | |
33 | static int ovl_check_redirect(const struct path *path, struct ovl_lookup_data *d, |
34 | size_t prelen, const char *post) |
35 | { |
36 | int res; |
37 | char *buf; |
38 | struct ovl_fs *ofs = OVL_FS(sb: d->sb); |
39 | |
40 | d->absolute_redirect = false; |
41 | buf = ovl_get_redirect_xattr(ofs, path, padding: prelen + strlen(post)); |
42 | if (IS_ERR_OR_NULL(ptr: buf)) |
43 | return PTR_ERR(ptr: buf); |
44 | |
45 | if (buf[0] == '/') { |
46 | d->absolute_redirect = true; |
47 | /* |
48 | * One of the ancestor path elements in an absolute path |
49 | * lookup in ovl_lookup_layer() could have been opaque and |
50 | * that will stop further lookup in lower layers (d->stop=true) |
51 | * But we have found an absolute redirect in descendant path |
52 | * element and that should force continue lookup in lower |
53 | * layers (reset d->stop). |
54 | */ |
55 | d->stop = false; |
56 | } else { |
57 | res = strlen(buf) + 1; |
58 | memmove(buf + prelen, buf, res); |
59 | memcpy(buf, d->name.name, prelen); |
60 | } |
61 | |
62 | strcat(p: buf, q: post); |
63 | kfree(objp: d->redirect); |
64 | d->redirect = buf; |
65 | d->name.name = d->redirect; |
66 | d->name.len = strlen(d->redirect); |
67 | |
68 | return 0; |
69 | } |
70 | |
71 | static int ovl_acceptable(void *ctx, struct dentry *dentry) |
72 | { |
73 | /* |
74 | * A non-dir origin may be disconnected, which is fine, because |
75 | * we only need it for its unique inode number. |
76 | */ |
77 | if (!d_is_dir(dentry)) |
78 | return 1; |
79 | |
80 | /* Don't decode a deleted empty directory */ |
81 | if (d_unhashed(dentry)) |
82 | return 0; |
83 | |
84 | /* Check if directory belongs to the layer we are decoding from */ |
85 | return is_subdir(dentry, ((struct vfsmount *)ctx)->mnt_root); |
86 | } |
87 | |
88 | /* |
89 | * Check validity of an overlay file handle buffer. |
90 | * |
91 | * Return 0 for a valid file handle. |
92 | * Return -ENODATA for "origin unknown". |
93 | * Return <0 for an invalid file handle. |
94 | */ |
95 | int ovl_check_fb_len(struct ovl_fb *fb, int fb_len) |
96 | { |
97 | if (fb_len < sizeof(struct ovl_fb) || fb_len < fb->len) |
98 | return -EINVAL; |
99 | |
100 | if (fb->magic != OVL_FH_MAGIC) |
101 | return -EINVAL; |
102 | |
103 | /* Treat larger version and unknown flags as "origin unknown" */ |
104 | if (fb->version > OVL_FH_VERSION || fb->flags & ~OVL_FH_FLAG_ALL) |
105 | return -ENODATA; |
106 | |
107 | /* Treat endianness mismatch as "origin unknown" */ |
108 | if (!(fb->flags & OVL_FH_FLAG_ANY_ENDIAN) && |
109 | (fb->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN) |
110 | return -ENODATA; |
111 | |
112 | return 0; |
113 | } |
114 | |
115 | static struct ovl_fh *ovl_get_fh(struct ovl_fs *ofs, struct dentry *upperdentry, |
116 | enum ovl_xattr ox) |
117 | { |
118 | int res, err; |
119 | struct ovl_fh *fh = NULL; |
120 | |
121 | res = ovl_getxattr_upper(ofs, upperdentry, ox, NULL, size: 0); |
122 | if (res < 0) { |
123 | if (res == -ENODATA || res == -EOPNOTSUPP) |
124 | return NULL; |
125 | goto fail; |
126 | } |
127 | /* Zero size value means "copied up but origin unknown" */ |
128 | if (res == 0) |
129 | return NULL; |
130 | |
131 | fh = kzalloc(size: res + OVL_FH_WIRE_OFFSET, GFP_KERNEL); |
132 | if (!fh) |
133 | return ERR_PTR(error: -ENOMEM); |
134 | |
135 | res = ovl_getxattr_upper(ofs, upperdentry, ox, value: fh->buf, size: res); |
136 | if (res < 0) |
137 | goto fail; |
138 | |
139 | err = ovl_check_fb_len(fb: &fh->fb, fb_len: res); |
140 | if (err < 0) { |
141 | if (err == -ENODATA) |
142 | goto out; |
143 | goto invalid; |
144 | } |
145 | |
146 | return fh; |
147 | |
148 | out: |
149 | kfree(objp: fh); |
150 | return NULL; |
151 | |
152 | fail: |
153 | pr_warn_ratelimited("failed to get origin (%i)\n" , res); |
154 | goto out; |
155 | invalid: |
156 | pr_warn_ratelimited("invalid origin (%*phN)\n" , res, fh); |
157 | goto out; |
158 | } |
159 | |
160 | struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh, |
161 | struct vfsmount *mnt, bool connected) |
162 | { |
163 | struct dentry *real; |
164 | int bytes; |
165 | |
166 | if (!capable(CAP_DAC_READ_SEARCH)) |
167 | return NULL; |
168 | |
169 | /* |
170 | * Make sure that the stored uuid matches the uuid of the lower |
171 | * layer where file handle will be decoded. |
172 | * In case of uuid=off option just make sure that stored uuid is null. |
173 | */ |
174 | if (ovl_origin_uuid(ofs) ? |
175 | !uuid_equal(u1: &fh->fb.uuid, u2: &mnt->mnt_sb->s_uuid) : |
176 | !uuid_is_null(uuid: &fh->fb.uuid)) |
177 | return NULL; |
178 | |
179 | bytes = (fh->fb.len - offsetof(struct ovl_fb, fid)); |
180 | real = exportfs_decode_fh(mnt, fid: (struct fid *)fh->fb.fid, |
181 | fh_len: bytes >> 2, fileid_type: (int)fh->fb.type, |
182 | acceptable: connected ? ovl_acceptable : NULL, context: mnt); |
183 | if (IS_ERR(ptr: real)) { |
184 | /* |
185 | * Treat stale file handle to lower file as "origin unknown". |
186 | * upper file handle could become stale when upper file is |
187 | * unlinked and this information is needed to handle stale |
188 | * index entries correctly. |
189 | */ |
190 | if (real == ERR_PTR(error: -ESTALE) && |
191 | !(fh->fb.flags & OVL_FH_FLAG_PATH_UPPER)) |
192 | real = NULL; |
193 | return real; |
194 | } |
195 | |
196 | if (ovl_dentry_weird(dentry: real)) { |
197 | dput(real); |
198 | return NULL; |
199 | } |
200 | |
201 | return real; |
202 | } |
203 | |
204 | static bool ovl_is_opaquedir(struct ovl_fs *ofs, const struct path *path) |
205 | { |
206 | return ovl_path_check_dir_xattr(ofs, path, ox: OVL_XATTR_OPAQUE); |
207 | } |
208 | |
209 | static struct dentry *ovl_lookup_positive_unlocked(struct ovl_lookup_data *d, |
210 | const char *name, |
211 | struct dentry *base, int len, |
212 | bool drop_negative) |
213 | { |
214 | struct dentry *ret = lookup_one_unlocked(idmap: mnt_idmap(mnt: d->mnt), name, base, len); |
215 | |
216 | if (!IS_ERR(ptr: ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { |
217 | if (drop_negative && ret->d_lockref.count == 1) { |
218 | spin_lock(lock: &ret->d_lock); |
219 | /* Recheck condition under lock */ |
220 | if (d_is_negative(dentry: ret) && ret->d_lockref.count == 1) |
221 | __d_drop(dentry: ret); |
222 | spin_unlock(lock: &ret->d_lock); |
223 | } |
224 | dput(ret); |
225 | ret = ERR_PTR(error: -ENOENT); |
226 | } |
227 | return ret; |
228 | } |
229 | |
230 | static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d, |
231 | const char *name, unsigned int namelen, |
232 | size_t prelen, const char *post, |
233 | struct dentry **ret, bool drop_negative) |
234 | { |
235 | struct dentry *this; |
236 | struct path path; |
237 | int err; |
238 | bool last_element = !post[0]; |
239 | |
240 | this = ovl_lookup_positive_unlocked(d, name, base, len: namelen, drop_negative); |
241 | if (IS_ERR(ptr: this)) { |
242 | err = PTR_ERR(ptr: this); |
243 | this = NULL; |
244 | if (err == -ENOENT || err == -ENAMETOOLONG) |
245 | goto out; |
246 | goto out_err; |
247 | } |
248 | |
249 | if (ovl_dentry_weird(dentry: this)) { |
250 | /* Don't support traversing automounts and other weirdness */ |
251 | err = -EREMOTE; |
252 | goto out_err; |
253 | } |
254 | |
255 | path.dentry = this; |
256 | path.mnt = d->mnt; |
257 | if (ovl_path_is_whiteout(ofs: OVL_FS(sb: d->sb), path: &path)) { |
258 | d->stop = d->opaque = true; |
259 | goto put_and_out; |
260 | } |
261 | /* |
262 | * This dentry should be a regular file if previous layer lookup |
263 | * found a metacopy dentry. |
264 | */ |
265 | if (last_element && d->metacopy && !d_is_reg(dentry: this)) { |
266 | d->stop = true; |
267 | goto put_and_out; |
268 | } |
269 | |
270 | if (!d_can_lookup(dentry: this)) { |
271 | if (d->is_dir || !last_element) { |
272 | d->stop = true; |
273 | goto put_and_out; |
274 | } |
275 | err = ovl_check_metacopy_xattr(ofs: OVL_FS(sb: d->sb), path: &path, NULL); |
276 | if (err < 0) |
277 | goto out_err; |
278 | |
279 | d->metacopy = err; |
280 | d->stop = !d->metacopy; |
281 | if (!d->metacopy || d->last) |
282 | goto out; |
283 | } else { |
284 | if (ovl_lookup_trap_inode(sb: d->sb, dir: this)) { |
285 | /* Caught in a trap of overlapping layers */ |
286 | err = -ELOOP; |
287 | goto out_err; |
288 | } |
289 | |
290 | if (last_element) |
291 | d->is_dir = true; |
292 | if (d->last) |
293 | goto out; |
294 | |
295 | if (ovl_is_opaquedir(ofs: OVL_FS(sb: d->sb), path: &path)) { |
296 | d->stop = true; |
297 | if (last_element) |
298 | d->opaque = true; |
299 | goto out; |
300 | } |
301 | } |
302 | err = ovl_check_redirect(path: &path, d, prelen, post); |
303 | if (err) |
304 | goto out_err; |
305 | out: |
306 | *ret = this; |
307 | return 0; |
308 | |
309 | put_and_out: |
310 | dput(this); |
311 | this = NULL; |
312 | goto out; |
313 | |
314 | out_err: |
315 | dput(this); |
316 | return err; |
317 | } |
318 | |
319 | static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, |
320 | struct dentry **ret, bool drop_negative) |
321 | { |
322 | /* Counting down from the end, since the prefix can change */ |
323 | size_t rem = d->name.len - 1; |
324 | struct dentry *dentry = NULL; |
325 | int err; |
326 | |
327 | if (d->name.name[0] != '/') |
328 | return ovl_lookup_single(base, d, name: d->name.name, namelen: d->name.len, |
329 | prelen: 0, post: "" , ret, drop_negative); |
330 | |
331 | while (!IS_ERR_OR_NULL(ptr: base) && d_can_lookup(dentry: base)) { |
332 | const char *s = d->name.name + d->name.len - rem; |
333 | const char *next = strchrnul(s, '/'); |
334 | size_t thislen = next - s; |
335 | bool end = !next[0]; |
336 | |
337 | /* Verify we did not go off the rails */ |
338 | if (WARN_ON(s[-1] != '/')) |
339 | return -EIO; |
340 | |
341 | err = ovl_lookup_single(base, d, name: s, namelen: thislen, |
342 | prelen: d->name.len - rem, post: next, ret: &base, |
343 | drop_negative); |
344 | dput(dentry); |
345 | if (err) |
346 | return err; |
347 | dentry = base; |
348 | if (end) |
349 | break; |
350 | |
351 | rem -= thislen + 1; |
352 | |
353 | if (WARN_ON(rem >= d->name.len)) |
354 | return -EIO; |
355 | } |
356 | *ret = dentry; |
357 | return 0; |
358 | } |
359 | |
360 | static int ovl_lookup_data_layer(struct dentry *dentry, const char *redirect, |
361 | const struct ovl_layer *layer, |
362 | struct path *datapath) |
363 | { |
364 | int err; |
365 | |
366 | err = vfs_path_lookup(layer->mnt->mnt_root, layer->mnt, redirect, |
367 | LOOKUP_BENEATH | LOOKUP_NO_SYMLINKS | LOOKUP_NO_XDEV, |
368 | datapath); |
369 | pr_debug("lookup lowerdata (%pd2, redirect=\"%s\", layer=%d, err=%i)\n" , |
370 | dentry, redirect, layer->idx, err); |
371 | |
372 | if (err) |
373 | return err; |
374 | |
375 | err = -EREMOTE; |
376 | if (ovl_dentry_weird(dentry: datapath->dentry)) |
377 | goto out_path_put; |
378 | |
379 | err = -ENOENT; |
380 | /* Only regular file is acceptable as lower data */ |
381 | if (!d_is_reg(dentry: datapath->dentry)) |
382 | goto out_path_put; |
383 | |
384 | return 0; |
385 | |
386 | out_path_put: |
387 | path_put(datapath); |
388 | |
389 | return err; |
390 | } |
391 | |
392 | /* Lookup in data-only layers by absolute redirect to layer root */ |
393 | static int ovl_lookup_data_layers(struct dentry *dentry, const char *redirect, |
394 | struct ovl_path *lowerdata) |
395 | { |
396 | struct ovl_fs *ofs = OVL_FS(sb: dentry->d_sb); |
397 | const struct ovl_layer *layer; |
398 | struct path datapath; |
399 | int err = -ENOENT; |
400 | int i; |
401 | |
402 | layer = &ofs->layers[ofs->numlayer - ofs->numdatalayer]; |
403 | for (i = 0; i < ofs->numdatalayer; i++, layer++) { |
404 | err = ovl_lookup_data_layer(dentry, redirect, layer, datapath: &datapath); |
405 | if (!err) { |
406 | mntput(mnt: datapath.mnt); |
407 | lowerdata->dentry = datapath.dentry; |
408 | lowerdata->layer = layer; |
409 | return 0; |
410 | } |
411 | } |
412 | |
413 | return err; |
414 | } |
415 | |
416 | int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected, |
417 | struct dentry *upperdentry, struct ovl_path **stackp) |
418 | { |
419 | struct dentry *origin = NULL; |
420 | int i; |
421 | |
422 | for (i = 1; i <= ovl_numlowerlayer(ofs); i++) { |
423 | /* |
424 | * If lower fs uuid is not unique among lower fs we cannot match |
425 | * fh->uuid to layer. |
426 | */ |
427 | if (ofs->layers[i].fsid && |
428 | ofs->layers[i].fs->bad_uuid) |
429 | continue; |
430 | |
431 | origin = ovl_decode_real_fh(ofs, fh, mnt: ofs->layers[i].mnt, |
432 | connected); |
433 | if (origin) |
434 | break; |
435 | } |
436 | |
437 | if (!origin) |
438 | return -ESTALE; |
439 | else if (IS_ERR(ptr: origin)) |
440 | return PTR_ERR(ptr: origin); |
441 | |
442 | if (upperdentry && !ovl_upper_is_whiteout(ofs, upperdentry) && |
443 | inode_wrong_type(inode: d_inode(dentry: upperdentry), mode: d_inode(dentry: origin)->i_mode)) |
444 | goto invalid; |
445 | |
446 | if (!*stackp) |
447 | *stackp = kmalloc(size: sizeof(struct ovl_path), GFP_KERNEL); |
448 | if (!*stackp) { |
449 | dput(origin); |
450 | return -ENOMEM; |
451 | } |
452 | **stackp = (struct ovl_path){ |
453 | .dentry = origin, |
454 | .layer = &ofs->layers[i] |
455 | }; |
456 | |
457 | return 0; |
458 | |
459 | invalid: |
460 | pr_warn_ratelimited("invalid origin (%pd2, ftype=%x, origin ftype=%x).\n" , |
461 | upperdentry, d_inode(upperdentry)->i_mode & S_IFMT, |
462 | d_inode(origin)->i_mode & S_IFMT); |
463 | dput(origin); |
464 | return -ESTALE; |
465 | } |
466 | |
467 | static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry, |
468 | struct ovl_path **stackp) |
469 | { |
470 | struct ovl_fh *fh = ovl_get_fh(ofs, upperdentry, ox: OVL_XATTR_ORIGIN); |
471 | int err; |
472 | |
473 | if (IS_ERR_OR_NULL(ptr: fh)) |
474 | return PTR_ERR(ptr: fh); |
475 | |
476 | err = ovl_check_origin_fh(ofs, fh, connected: false, upperdentry, stackp); |
477 | kfree(objp: fh); |
478 | |
479 | if (err) { |
480 | if (err == -ESTALE) |
481 | return 0; |
482 | return err; |
483 | } |
484 | |
485 | return 0; |
486 | } |
487 | |
488 | /* |
489 | * Verify that @fh matches the file handle stored in xattr @name. |
490 | * Return 0 on match, -ESTALE on mismatch, < 0 on error. |
491 | */ |
492 | static int ovl_verify_fh(struct ovl_fs *ofs, struct dentry *dentry, |
493 | enum ovl_xattr ox, const struct ovl_fh *fh) |
494 | { |
495 | struct ovl_fh *ofh = ovl_get_fh(ofs, upperdentry: dentry, ox); |
496 | int err = 0; |
497 | |
498 | if (!ofh) |
499 | return -ENODATA; |
500 | |
501 | if (IS_ERR(ptr: ofh)) |
502 | return PTR_ERR(ptr: ofh); |
503 | |
504 | if (fh->fb.len != ofh->fb.len || memcmp(p: &fh->fb, q: &ofh->fb, size: fh->fb.len)) |
505 | err = -ESTALE; |
506 | |
507 | kfree(objp: ofh); |
508 | return err; |
509 | } |
510 | |
511 | int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry, |
512 | enum ovl_xattr ox, const struct ovl_fh *fh, |
513 | bool is_upper, bool set) |
514 | { |
515 | int err; |
516 | |
517 | err = ovl_verify_fh(ofs, dentry, ox, fh); |
518 | if (set && err == -ENODATA) |
519 | err = ovl_setxattr(ofs, dentry, ox, value: fh->buf, size: fh->fb.len); |
520 | |
521 | return err; |
522 | } |
523 | |
524 | /* |
525 | * Verify that @real dentry matches the file handle stored in xattr @name. |
526 | * |
527 | * If @set is true and there is no stored file handle, encode @real and store |
528 | * file handle in xattr @name. |
529 | * |
530 | * Return 0 on match, -ESTALE on mismatch, -ENODATA on no xattr, < 0 on error. |
531 | */ |
532 | int ovl_verify_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry, |
533 | enum ovl_xattr ox, struct dentry *real, |
534 | bool is_upper, bool set) |
535 | { |
536 | struct inode *inode; |
537 | struct ovl_fh *fh; |
538 | int err; |
539 | |
540 | fh = ovl_encode_real_fh(ofs, real, is_upper); |
541 | err = PTR_ERR(ptr: fh); |
542 | if (IS_ERR(ptr: fh)) { |
543 | fh = NULL; |
544 | goto fail; |
545 | } |
546 | |
547 | err = ovl_verify_set_fh(ofs, dentry, ox, fh, is_upper, set); |
548 | if (err) |
549 | goto fail; |
550 | |
551 | out: |
552 | kfree(objp: fh); |
553 | return err; |
554 | |
555 | fail: |
556 | inode = d_inode(dentry: real); |
557 | pr_warn_ratelimited("failed to verify %s (%pd2, ino=%lu, err=%i)\n" , |
558 | is_upper ? "upper" : "origin" , real, |
559 | inode ? inode->i_ino : 0, err); |
560 | goto out; |
561 | } |
562 | |
563 | |
564 | /* Get upper dentry from index */ |
565 | struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index, |
566 | bool connected) |
567 | { |
568 | struct ovl_fh *fh; |
569 | struct dentry *upper; |
570 | |
571 | if (!d_is_dir(dentry: index)) |
572 | return dget(dentry: index); |
573 | |
574 | fh = ovl_get_fh(ofs, upperdentry: index, ox: OVL_XATTR_UPPER); |
575 | if (IS_ERR_OR_NULL(ptr: fh)) |
576 | return ERR_CAST(ptr: fh); |
577 | |
578 | upper = ovl_decode_real_fh(ofs, fh, mnt: ovl_upper_mnt(ofs), connected); |
579 | kfree(objp: fh); |
580 | |
581 | if (IS_ERR_OR_NULL(ptr: upper)) |
582 | return upper ?: ERR_PTR(error: -ESTALE); |
583 | |
584 | if (!d_is_dir(dentry: upper)) { |
585 | pr_warn_ratelimited("invalid index upper (%pd2, upper=%pd2).\n" , |
586 | index, upper); |
587 | dput(upper); |
588 | return ERR_PTR(error: -EIO); |
589 | } |
590 | |
591 | return upper; |
592 | } |
593 | |
594 | /* |
595 | * Verify that an index entry name matches the origin file handle stored in |
596 | * OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path. |
597 | * Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error. |
598 | */ |
599 | int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index) |
600 | { |
601 | struct ovl_fh *fh = NULL; |
602 | size_t len; |
603 | struct ovl_path origin = { }; |
604 | struct ovl_path *stack = &origin; |
605 | struct dentry *upper = NULL; |
606 | int err; |
607 | |
608 | if (!d_inode(dentry: index)) |
609 | return 0; |
610 | |
611 | err = -EINVAL; |
612 | if (index->d_name.len < sizeof(struct ovl_fb)*2) |
613 | goto fail; |
614 | |
615 | err = -ENOMEM; |
616 | len = index->d_name.len / 2; |
617 | fh = kzalloc(size: len + OVL_FH_WIRE_OFFSET, GFP_KERNEL); |
618 | if (!fh) |
619 | goto fail; |
620 | |
621 | err = -EINVAL; |
622 | if (hex2bin(dst: fh->buf, src: index->d_name.name, count: len)) |
623 | goto fail; |
624 | |
625 | err = ovl_check_fb_len(fb: &fh->fb, fb_len: len); |
626 | if (err) |
627 | goto fail; |
628 | |
629 | /* |
630 | * Whiteout index entries are used as an indication that an exported |
631 | * overlay file handle should be treated as stale (i.e. after unlink |
632 | * of the overlay inode). These entries contain no origin xattr. |
633 | */ |
634 | if (ovl_is_whiteout(dentry: index)) |
635 | goto out; |
636 | |
637 | /* |
638 | * Verifying directory index entries are not stale is expensive, so |
639 | * only verify stale dir index if NFS export is enabled. |
640 | */ |
641 | if (d_is_dir(dentry: index) && !ofs->config.nfs_export) |
642 | goto out; |
643 | |
644 | /* |
645 | * Directory index entries should have 'upper' xattr pointing to the |
646 | * real upper dir. Non-dir index entries are hardlinks to the upper |
647 | * real inode. For non-dir index, we can read the copy up origin xattr |
648 | * directly from the index dentry, but for dir index we first need to |
649 | * decode the upper directory. |
650 | */ |
651 | upper = ovl_index_upper(ofs, index, connected: false); |
652 | if (IS_ERR_OR_NULL(ptr: upper)) { |
653 | err = PTR_ERR(ptr: upper); |
654 | /* |
655 | * Directory index entries with no 'upper' xattr need to be |
656 | * removed. When dir index entry has a stale 'upper' xattr, |
657 | * we assume that upper dir was removed and we treat the dir |
658 | * index as orphan entry that needs to be whited out. |
659 | */ |
660 | if (err == -ESTALE) |
661 | goto orphan; |
662 | else if (!err) |
663 | err = -ESTALE; |
664 | goto fail; |
665 | } |
666 | |
667 | err = ovl_verify_fh(ofs, dentry: upper, ox: OVL_XATTR_ORIGIN, fh); |
668 | dput(upper); |
669 | if (err) |
670 | goto fail; |
671 | |
672 | /* Check if non-dir index is orphan and don't warn before cleaning it */ |
673 | if (!d_is_dir(dentry: index) && d_inode(dentry: index)->i_nlink == 1) { |
674 | err = ovl_check_origin_fh(ofs, fh, connected: false, upperdentry: index, stackp: &stack); |
675 | if (err) |
676 | goto fail; |
677 | |
678 | if (ovl_get_nlink(ofs, lowerdentry: origin.dentry, upperdentry: index, fallback: 0) == 0) |
679 | goto orphan; |
680 | } |
681 | |
682 | out: |
683 | dput(origin.dentry); |
684 | kfree(objp: fh); |
685 | return err; |
686 | |
687 | fail: |
688 | pr_warn_ratelimited("failed to verify index (%pd2, ftype=%x, err=%i)\n" , |
689 | index, d_inode(index)->i_mode & S_IFMT, err); |
690 | goto out; |
691 | |
692 | orphan: |
693 | pr_warn_ratelimited("orphan index entry (%pd2, ftype=%x, nlink=%u)\n" , |
694 | index, d_inode(index)->i_mode & S_IFMT, |
695 | d_inode(index)->i_nlink); |
696 | err = -ENOENT; |
697 | goto out; |
698 | } |
699 | |
700 | int ovl_get_index_name_fh(const struct ovl_fh *fh, struct qstr *name) |
701 | { |
702 | char *n, *s; |
703 | |
704 | n = kcalloc(n: fh->fb.len, size: 2, GFP_KERNEL); |
705 | if (!n) |
706 | return -ENOMEM; |
707 | |
708 | s = bin2hex(dst: n, src: fh->buf, count: fh->fb.len); |
709 | *name = (struct qstr) QSTR_INIT(n, s - n); |
710 | |
711 | return 0; |
712 | |
713 | } |
714 | |
715 | /* |
716 | * Lookup in indexdir for the index entry of a lower real inode or a copy up |
717 | * origin inode. The index entry name is the hex representation of the lower |
718 | * inode file handle. |
719 | * |
720 | * If the index dentry in negative, then either no lower aliases have been |
721 | * copied up yet, or aliases have been copied up in older kernels and are |
722 | * not indexed. |
723 | * |
724 | * If the index dentry for a copy up origin inode is positive, but points |
725 | * to an inode different than the upper inode, then either the upper inode |
726 | * has been copied up and not indexed or it was indexed, but since then |
727 | * index dir was cleared. Either way, that index cannot be used to identify |
728 | * the overlay inode. |
729 | */ |
730 | int ovl_get_index_name(struct ovl_fs *ofs, struct dentry *origin, |
731 | struct qstr *name) |
732 | { |
733 | struct ovl_fh *fh; |
734 | int err; |
735 | |
736 | fh = ovl_encode_real_fh(ofs, real: origin, is_upper: false); |
737 | if (IS_ERR(ptr: fh)) |
738 | return PTR_ERR(ptr: fh); |
739 | |
740 | err = ovl_get_index_name_fh(fh, name); |
741 | |
742 | kfree(objp: fh); |
743 | return err; |
744 | } |
745 | |
746 | /* Lookup index by file handle for NFS export */ |
747 | struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh) |
748 | { |
749 | struct dentry *index; |
750 | struct qstr name; |
751 | int err; |
752 | |
753 | err = ovl_get_index_name_fh(fh, name: &name); |
754 | if (err) |
755 | return ERR_PTR(error: err); |
756 | |
757 | index = lookup_positive_unlocked(name.name, ofs->indexdir, name.len); |
758 | kfree(objp: name.name); |
759 | if (IS_ERR(ptr: index)) { |
760 | if (PTR_ERR(ptr: index) == -ENOENT) |
761 | index = NULL; |
762 | return index; |
763 | } |
764 | |
765 | if (ovl_is_whiteout(dentry: index)) |
766 | err = -ESTALE; |
767 | else if (ovl_dentry_weird(dentry: index)) |
768 | err = -EIO; |
769 | else |
770 | return index; |
771 | |
772 | dput(index); |
773 | return ERR_PTR(error: err); |
774 | } |
775 | |
776 | struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper, |
777 | struct dentry *origin, bool verify) |
778 | { |
779 | struct dentry *index; |
780 | struct inode *inode; |
781 | struct qstr name; |
782 | bool is_dir = d_is_dir(dentry: origin); |
783 | int err; |
784 | |
785 | err = ovl_get_index_name(ofs, origin, name: &name); |
786 | if (err) |
787 | return ERR_PTR(error: err); |
788 | |
789 | index = lookup_one_positive_unlocked(idmap: ovl_upper_mnt_idmap(ofs), name: name.name, |
790 | base: ofs->indexdir, len: name.len); |
791 | if (IS_ERR(ptr: index)) { |
792 | err = PTR_ERR(ptr: index); |
793 | if (err == -ENOENT) { |
794 | index = NULL; |
795 | goto out; |
796 | } |
797 | pr_warn_ratelimited("failed inode index lookup (ino=%lu, key=%.*s, err=%i);\n" |
798 | "overlayfs: mount with '-o index=off' to disable inodes index.\n" , |
799 | d_inode(origin)->i_ino, name.len, name.name, |
800 | err); |
801 | goto out; |
802 | } |
803 | |
804 | inode = d_inode(dentry: index); |
805 | if (ovl_is_whiteout(dentry: index) && !verify) { |
806 | /* |
807 | * When index lookup is called with !verify for decoding an |
808 | * overlay file handle, a whiteout index implies that decode |
809 | * should treat file handle as stale and no need to print a |
810 | * warning about it. |
811 | */ |
812 | dput(index); |
813 | index = ERR_PTR(error: -ESTALE); |
814 | goto out; |
815 | } else if (ovl_dentry_weird(dentry: index) || ovl_is_whiteout(dentry: index) || |
816 | inode_wrong_type(inode, mode: d_inode(dentry: origin)->i_mode)) { |
817 | /* |
818 | * Index should always be of the same file type as origin |
819 | * except for the case of a whiteout index. A whiteout |
820 | * index should only exist if all lower aliases have been |
821 | * unlinked, which means that finding a lower origin on lookup |
822 | * whose index is a whiteout should be treated as an error. |
823 | */ |
824 | pr_warn_ratelimited("bad index found (index=%pd2, ftype=%x, origin ftype=%x).\n" , |
825 | index, d_inode(index)->i_mode & S_IFMT, |
826 | d_inode(origin)->i_mode & S_IFMT); |
827 | goto fail; |
828 | } else if (is_dir && verify) { |
829 | if (!upper) { |
830 | pr_warn_ratelimited("suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n" , |
831 | origin, index); |
832 | goto fail; |
833 | } |
834 | |
835 | /* Verify that dir index 'upper' xattr points to upper dir */ |
836 | err = ovl_verify_upper(ofs, index, upper, set: false); |
837 | if (err) { |
838 | if (err == -ESTALE) { |
839 | pr_warn_ratelimited("suspected multiply redirected dir found (upper=%pd2, origin=%pd2, index=%pd2).\n" , |
840 | upper, origin, index); |
841 | } |
842 | goto fail; |
843 | } |
844 | } else if (upper && d_inode(dentry: upper) != inode) { |
845 | goto out_dput; |
846 | } |
847 | out: |
848 | kfree(objp: name.name); |
849 | return index; |
850 | |
851 | out_dput: |
852 | dput(index); |
853 | index = NULL; |
854 | goto out; |
855 | |
856 | fail: |
857 | dput(index); |
858 | index = ERR_PTR(error: -EIO); |
859 | goto out; |
860 | } |
861 | |
862 | /* |
863 | * Returns next layer in stack starting from top. |
864 | * Returns -1 if this is the last layer. |
865 | */ |
866 | int ovl_path_next(int idx, struct dentry *dentry, struct path *path) |
867 | { |
868 | struct ovl_entry *oe = OVL_E(dentry); |
869 | struct ovl_path *lowerstack = ovl_lowerstack(oe); |
870 | |
871 | BUG_ON(idx < 0); |
872 | if (idx == 0) { |
873 | ovl_path_upper(dentry, path); |
874 | if (path->dentry) |
875 | return ovl_numlower(oe) ? 1 : -1; |
876 | idx++; |
877 | } |
878 | BUG_ON(idx > ovl_numlower(oe)); |
879 | path->dentry = lowerstack[idx - 1].dentry; |
880 | path->mnt = lowerstack[idx - 1].layer->mnt; |
881 | |
882 | return (idx < ovl_numlower(oe)) ? idx + 1 : -1; |
883 | } |
884 | |
885 | /* Fix missing 'origin' xattr */ |
886 | static int ovl_fix_origin(struct ovl_fs *ofs, struct dentry *dentry, |
887 | struct dentry *lower, struct dentry *upper) |
888 | { |
889 | const struct ovl_fh *fh; |
890 | int err; |
891 | |
892 | if (ovl_check_origin_xattr(ofs, upperdentry: upper)) |
893 | return 0; |
894 | |
895 | fh = ovl_get_origin_fh(ofs, origin: lower); |
896 | if (IS_ERR(ptr: fh)) |
897 | return PTR_ERR(ptr: fh); |
898 | |
899 | err = ovl_want_write(dentry); |
900 | if (err) |
901 | goto out; |
902 | |
903 | err = ovl_set_origin_fh(ofs, fh, upper); |
904 | if (!err) |
905 | err = ovl_set_impure(dentry: dentry->d_parent, upperdentry: upper->d_parent); |
906 | |
907 | ovl_drop_write(dentry); |
908 | out: |
909 | kfree(objp: fh); |
910 | return err; |
911 | } |
912 | |
913 | static int ovl_maybe_validate_verity(struct dentry *dentry) |
914 | { |
915 | struct ovl_fs *ofs = OVL_FS(sb: dentry->d_sb); |
916 | struct inode *inode = d_inode(dentry); |
917 | struct path datapath, metapath; |
918 | int err; |
919 | |
920 | if (!ofs->config.verity_mode || |
921 | !ovl_is_metacopy_dentry(dentry) || |
922 | ovl_test_flag(flag: OVL_VERIFIED_DIGEST, inode)) |
923 | return 0; |
924 | |
925 | if (!ovl_test_flag(flag: OVL_HAS_DIGEST, inode)) { |
926 | if (ofs->config.verity_mode == OVL_VERITY_REQUIRE) { |
927 | pr_warn_ratelimited("metacopy file '%pd' has no digest specified\n" , |
928 | dentry); |
929 | return -EIO; |
930 | } |
931 | return 0; |
932 | } |
933 | |
934 | ovl_path_lowerdata(dentry, path: &datapath); |
935 | if (!datapath.dentry) |
936 | return -EIO; |
937 | |
938 | ovl_path_real(dentry, path: &metapath); |
939 | if (!metapath.dentry) |
940 | return -EIO; |
941 | |
942 | err = ovl_inode_lock_interruptible(inode); |
943 | if (err) |
944 | return err; |
945 | |
946 | if (!ovl_test_flag(flag: OVL_VERIFIED_DIGEST, inode)) { |
947 | const struct cred *old_cred; |
948 | |
949 | old_cred = ovl_override_creds(sb: dentry->d_sb); |
950 | |
951 | err = ovl_validate_verity(ofs, metapath: &metapath, datapath: &datapath); |
952 | if (err == 0) |
953 | ovl_set_flag(flag: OVL_VERIFIED_DIGEST, inode); |
954 | |
955 | revert_creds(old_cred); |
956 | } |
957 | |
958 | ovl_inode_unlock(inode); |
959 | |
960 | return err; |
961 | } |
962 | |
963 | /* Lazy lookup of lowerdata */ |
964 | static int ovl_maybe_lookup_lowerdata(struct dentry *dentry) |
965 | { |
966 | struct inode *inode = d_inode(dentry); |
967 | const char *redirect = ovl_lowerdata_redirect(inode); |
968 | struct ovl_path datapath = {}; |
969 | const struct cred *old_cred; |
970 | int err; |
971 | |
972 | if (!redirect || ovl_dentry_lowerdata(dentry)) |
973 | return 0; |
974 | |
975 | if (redirect[0] != '/') |
976 | return -EIO; |
977 | |
978 | err = ovl_inode_lock_interruptible(inode); |
979 | if (err) |
980 | return err; |
981 | |
982 | err = 0; |
983 | /* Someone got here before us? */ |
984 | if (ovl_dentry_lowerdata(dentry)) |
985 | goto out; |
986 | |
987 | old_cred = ovl_override_creds(sb: dentry->d_sb); |
988 | err = ovl_lookup_data_layers(dentry, redirect, lowerdata: &datapath); |
989 | revert_creds(old_cred); |
990 | if (err) |
991 | goto out_err; |
992 | |
993 | err = ovl_dentry_set_lowerdata(dentry, datapath: &datapath); |
994 | if (err) |
995 | goto out_err; |
996 | |
997 | out: |
998 | ovl_inode_unlock(inode); |
999 | dput(datapath.dentry); |
1000 | |
1001 | return err; |
1002 | |
1003 | out_err: |
1004 | pr_warn_ratelimited("lazy lowerdata lookup failed (%pd2, err=%i)\n" , |
1005 | dentry, err); |
1006 | goto out; |
1007 | } |
1008 | |
1009 | int ovl_verify_lowerdata(struct dentry *dentry) |
1010 | { |
1011 | int err; |
1012 | |
1013 | err = ovl_maybe_lookup_lowerdata(dentry); |
1014 | if (err) |
1015 | return err; |
1016 | |
1017 | return ovl_maybe_validate_verity(dentry); |
1018 | } |
1019 | |
1020 | struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, |
1021 | unsigned int flags) |
1022 | { |
1023 | struct ovl_entry *oe = NULL; |
1024 | const struct cred *old_cred; |
1025 | struct ovl_fs *ofs = OVL_FS(sb: dentry->d_sb); |
1026 | struct ovl_entry *poe = OVL_E(dentry: dentry->d_parent); |
1027 | struct ovl_entry *roe = OVL_E(dentry: dentry->d_sb->s_root); |
1028 | struct ovl_path *stack = NULL, *origin_path = NULL; |
1029 | struct dentry *upperdir, *upperdentry = NULL; |
1030 | struct dentry *origin = NULL; |
1031 | struct dentry *index = NULL; |
1032 | unsigned int ctr = 0; |
1033 | struct inode *inode = NULL; |
1034 | bool upperopaque = false; |
1035 | char *upperredirect = NULL; |
1036 | struct dentry *this; |
1037 | unsigned int i; |
1038 | int err; |
1039 | bool uppermetacopy = false; |
1040 | int metacopy_size = 0; |
1041 | struct ovl_lookup_data d = { |
1042 | .sb = dentry->d_sb, |
1043 | .name = dentry->d_name, |
1044 | .is_dir = false, |
1045 | .opaque = false, |
1046 | .stop = false, |
1047 | .last = ovl_redirect_follow(ofs) ? false : !ovl_numlower(oe: poe), |
1048 | .redirect = NULL, |
1049 | .metacopy = 0, |
1050 | }; |
1051 | |
1052 | if (dentry->d_name.len > ofs->namelen) |
1053 | return ERR_PTR(error: -ENAMETOOLONG); |
1054 | |
1055 | old_cred = ovl_override_creds(sb: dentry->d_sb); |
1056 | upperdir = ovl_dentry_upper(dentry: dentry->d_parent); |
1057 | if (upperdir) { |
1058 | d.mnt = ovl_upper_mnt(ofs); |
1059 | err = ovl_lookup_layer(base: upperdir, d: &d, ret: &upperdentry, drop_negative: true); |
1060 | if (err) |
1061 | goto out; |
1062 | |
1063 | if (upperdentry && upperdentry->d_flags & DCACHE_OP_REAL) { |
1064 | dput(upperdentry); |
1065 | err = -EREMOTE; |
1066 | goto out; |
1067 | } |
1068 | if (upperdentry && !d.is_dir) { |
1069 | /* |
1070 | * Lookup copy up origin by decoding origin file handle. |
1071 | * We may get a disconnected dentry, which is fine, |
1072 | * because we only need to hold the origin inode in |
1073 | * cache and use its inode number. We may even get a |
1074 | * connected dentry, that is not under any of the lower |
1075 | * layers root. That is also fine for using it's inode |
1076 | * number - it's the same as if we held a reference |
1077 | * to a dentry in lower layer that was moved under us. |
1078 | */ |
1079 | err = ovl_check_origin(ofs, upperdentry, stackp: &origin_path); |
1080 | if (err) |
1081 | goto out_put_upper; |
1082 | |
1083 | if (d.metacopy) |
1084 | uppermetacopy = true; |
1085 | metacopy_size = d.metacopy; |
1086 | } |
1087 | |
1088 | if (d.redirect) { |
1089 | err = -ENOMEM; |
1090 | upperredirect = kstrdup(s: d.redirect, GFP_KERNEL); |
1091 | if (!upperredirect) |
1092 | goto out_put_upper; |
1093 | if (d.redirect[0] == '/') |
1094 | poe = roe; |
1095 | } |
1096 | upperopaque = d.opaque; |
1097 | } |
1098 | |
1099 | if (!d.stop && ovl_numlower(oe: poe)) { |
1100 | err = -ENOMEM; |
1101 | stack = ovl_stack_alloc(n: ofs->numlayer - 1); |
1102 | if (!stack) |
1103 | goto out_put_upper; |
1104 | } |
1105 | |
1106 | for (i = 0; !d.stop && i < ovl_numlower(oe: poe); i++) { |
1107 | struct ovl_path lower = ovl_lowerstack(oe: poe)[i]; |
1108 | |
1109 | if (!ovl_redirect_follow(ofs)) |
1110 | d.last = i == ovl_numlower(oe: poe) - 1; |
1111 | else if (d.is_dir || !ofs->numdatalayer) |
1112 | d.last = lower.layer->idx == ovl_numlower(oe: roe); |
1113 | |
1114 | d.mnt = lower.layer->mnt; |
1115 | err = ovl_lookup_layer(base: lower.dentry, d: &d, ret: &this, drop_negative: false); |
1116 | if (err) |
1117 | goto out_put; |
1118 | |
1119 | if (!this) |
1120 | continue; |
1121 | |
1122 | if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) { |
1123 | dput(this); |
1124 | err = -EPERM; |
1125 | pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n" , dentry); |
1126 | goto out_put; |
1127 | } |
1128 | |
1129 | /* |
1130 | * If no origin fh is stored in upper of a merge dir, store fh |
1131 | * of lower dir and set upper parent "impure". |
1132 | */ |
1133 | if (upperdentry && !ctr && !ofs->noxattr && d.is_dir) { |
1134 | err = ovl_fix_origin(ofs, dentry, lower: this, upper: upperdentry); |
1135 | if (err) { |
1136 | dput(this); |
1137 | goto out_put; |
1138 | } |
1139 | } |
1140 | |
1141 | /* |
1142 | * When "verify_lower" feature is enabled, do not merge with a |
1143 | * lower dir that does not match a stored origin xattr. In any |
1144 | * case, only verified origin is used for index lookup. |
1145 | * |
1146 | * For non-dir dentry, if index=on, then ensure origin |
1147 | * matches the dentry found using path based lookup, |
1148 | * otherwise error out. |
1149 | */ |
1150 | if (upperdentry && !ctr && |
1151 | ((d.is_dir && ovl_verify_lower(sb: dentry->d_sb)) || |
1152 | (!d.is_dir && ofs->config.index && origin_path))) { |
1153 | err = ovl_verify_origin(ofs, upper: upperdentry, origin: this, set: false); |
1154 | if (err) { |
1155 | dput(this); |
1156 | if (d.is_dir) |
1157 | break; |
1158 | goto out_put; |
1159 | } |
1160 | origin = this; |
1161 | } |
1162 | |
1163 | if (!upperdentry && !d.is_dir && !ctr && d.metacopy) |
1164 | metacopy_size = d.metacopy; |
1165 | |
1166 | if (d.metacopy && ctr) { |
1167 | /* |
1168 | * Do not store intermediate metacopy dentries in |
1169 | * lower chain, except top most lower metacopy dentry. |
1170 | * Continue the loop so that if there is an absolute |
1171 | * redirect on this dentry, poe can be reset to roe. |
1172 | */ |
1173 | dput(this); |
1174 | this = NULL; |
1175 | } else { |
1176 | stack[ctr].dentry = this; |
1177 | stack[ctr].layer = lower.layer; |
1178 | ctr++; |
1179 | } |
1180 | |
1181 | /* |
1182 | * Following redirects can have security consequences: it's like |
1183 | * a symlink into the lower layer without the permission checks. |
1184 | * This is only a problem if the upper layer is untrusted (e.g |
1185 | * comes from an USB drive). This can allow a non-readable file |
1186 | * or directory to become readable. |
1187 | * |
1188 | * Only following redirects when redirects are enabled disables |
1189 | * this attack vector when not necessary. |
1190 | */ |
1191 | err = -EPERM; |
1192 | if (d.redirect && !ovl_redirect_follow(ofs)) { |
1193 | pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n" , |
1194 | dentry); |
1195 | goto out_put; |
1196 | } |
1197 | |
1198 | if (d.stop) |
1199 | break; |
1200 | |
1201 | if (d.redirect && d.redirect[0] == '/' && poe != roe) { |
1202 | poe = roe; |
1203 | /* Find the current layer on the root dentry */ |
1204 | i = lower.layer->idx - 1; |
1205 | } |
1206 | } |
1207 | |
1208 | /* Defer lookup of lowerdata in data-only layers to first access */ |
1209 | if (d.metacopy && ctr && ofs->numdatalayer && d.absolute_redirect) { |
1210 | d.metacopy = 0; |
1211 | ctr++; |
1212 | } |
1213 | |
1214 | /* |
1215 | * For regular non-metacopy upper dentries, there is no lower |
1216 | * path based lookup, hence ctr will be zero. If a dentry is found |
1217 | * using ORIGIN xattr on upper, install it in stack. |
1218 | * |
1219 | * For metacopy dentry, path based lookup will find lower dentries. |
1220 | * Just make sure a corresponding data dentry has been found. |
1221 | */ |
1222 | if (d.metacopy || (uppermetacopy && !ctr)) { |
1223 | pr_warn_ratelimited("metacopy with no lower data found - abort lookup (%pd2)\n" , |
1224 | dentry); |
1225 | err = -EIO; |
1226 | goto out_put; |
1227 | } else if (!d.is_dir && upperdentry && !ctr && origin_path) { |
1228 | if (WARN_ON(stack != NULL)) { |
1229 | err = -EIO; |
1230 | goto out_put; |
1231 | } |
1232 | stack = origin_path; |
1233 | ctr = 1; |
1234 | origin = origin_path->dentry; |
1235 | origin_path = NULL; |
1236 | } |
1237 | |
1238 | /* |
1239 | * Always lookup index if there is no-upperdentry. |
1240 | * |
1241 | * For the case of upperdentry, we have set origin by now if it |
1242 | * needed to be set. There are basically three cases. |
1243 | * |
1244 | * For directories, lookup index by lower inode and verify it matches |
1245 | * upper inode. We only trust dir index if we verified that lower dir |
1246 | * matches origin, otherwise dir index entries may be inconsistent |
1247 | * and we ignore them. |
1248 | * |
1249 | * For regular upper, we already set origin if upper had ORIGIN |
1250 | * xattr. There is no verification though as there is no path |
1251 | * based dentry lookup in lower in this case. |
1252 | * |
1253 | * For metacopy upper, we set a verified origin already if index |
1254 | * is enabled and if upper had an ORIGIN xattr. |
1255 | * |
1256 | */ |
1257 | if (!upperdentry && ctr) |
1258 | origin = stack[0].dentry; |
1259 | |
1260 | if (origin && ovl_indexdir(sb: dentry->d_sb) && |
1261 | (!d.is_dir || ovl_index_all(sb: dentry->d_sb))) { |
1262 | index = ovl_lookup_index(ofs, upper: upperdentry, origin, verify: true); |
1263 | if (IS_ERR(ptr: index)) { |
1264 | err = PTR_ERR(ptr: index); |
1265 | index = NULL; |
1266 | goto out_put; |
1267 | } |
1268 | } |
1269 | |
1270 | if (ctr) { |
1271 | oe = ovl_alloc_entry(numlower: ctr); |
1272 | err = -ENOMEM; |
1273 | if (!oe) |
1274 | goto out_put; |
1275 | |
1276 | ovl_stack_cpy(dst: ovl_lowerstack(oe), src: stack, n: ctr); |
1277 | } |
1278 | |
1279 | if (upperopaque) |
1280 | ovl_dentry_set_opaque(dentry); |
1281 | |
1282 | if (upperdentry) |
1283 | ovl_dentry_set_upper_alias(dentry); |
1284 | else if (index) { |
1285 | struct path upperpath = { |
1286 | .dentry = upperdentry = dget(dentry: index), |
1287 | .mnt = ovl_upper_mnt(ofs), |
1288 | }; |
1289 | |
1290 | /* |
1291 | * It's safe to assign upperredirect here: the previous |
1292 | * assignment of happens only if upperdentry is non-NULL, and |
1293 | * this one only if upperdentry is NULL. |
1294 | */ |
1295 | upperredirect = ovl_get_redirect_xattr(ofs, path: &upperpath, padding: 0); |
1296 | if (IS_ERR(ptr: upperredirect)) { |
1297 | err = PTR_ERR(ptr: upperredirect); |
1298 | upperredirect = NULL; |
1299 | goto out_free_oe; |
1300 | } |
1301 | err = ovl_check_metacopy_xattr(ofs, path: &upperpath, NULL); |
1302 | if (err < 0) |
1303 | goto out_free_oe; |
1304 | uppermetacopy = err; |
1305 | metacopy_size = err; |
1306 | } |
1307 | |
1308 | if (upperdentry || ctr) { |
1309 | struct ovl_inode_params oip = { |
1310 | .upperdentry = upperdentry, |
1311 | .oe = oe, |
1312 | .index = index, |
1313 | .redirect = upperredirect, |
1314 | }; |
1315 | |
1316 | /* Store lowerdata redirect for lazy lookup */ |
1317 | if (ctr > 1 && !d.is_dir && !stack[ctr - 1].dentry) { |
1318 | oip.lowerdata_redirect = d.redirect; |
1319 | d.redirect = NULL; |
1320 | } |
1321 | inode = ovl_get_inode(sb: dentry->d_sb, oip: &oip); |
1322 | err = PTR_ERR(ptr: inode); |
1323 | if (IS_ERR(ptr: inode)) |
1324 | goto out_free_oe; |
1325 | if (upperdentry && !uppermetacopy) |
1326 | ovl_set_flag(flag: OVL_UPPERDATA, inode); |
1327 | |
1328 | if (metacopy_size > OVL_METACOPY_MIN_SIZE) |
1329 | ovl_set_flag(flag: OVL_HAS_DIGEST, inode); |
1330 | } |
1331 | |
1332 | ovl_dentry_init_reval(dentry, upperdentry, oe: OVL_I_E(inode)); |
1333 | |
1334 | revert_creds(old_cred); |
1335 | if (origin_path) { |
1336 | dput(origin_path->dentry); |
1337 | kfree(objp: origin_path); |
1338 | } |
1339 | dput(index); |
1340 | ovl_stack_free(stack, n: ctr); |
1341 | kfree(objp: d.redirect); |
1342 | return d_splice_alias(inode, dentry); |
1343 | |
1344 | out_free_oe: |
1345 | ovl_free_entry(oe); |
1346 | out_put: |
1347 | dput(index); |
1348 | ovl_stack_free(stack, n: ctr); |
1349 | out_put_upper: |
1350 | if (origin_path) { |
1351 | dput(origin_path->dentry); |
1352 | kfree(objp: origin_path); |
1353 | } |
1354 | dput(upperdentry); |
1355 | kfree(objp: upperredirect); |
1356 | out: |
1357 | kfree(objp: d.redirect); |
1358 | revert_creds(old_cred); |
1359 | return ERR_PTR(error: err); |
1360 | } |
1361 | |
1362 | bool ovl_lower_positive(struct dentry *dentry) |
1363 | { |
1364 | struct ovl_entry *poe = OVL_E(dentry: dentry->d_parent); |
1365 | const struct qstr *name = &dentry->d_name; |
1366 | const struct cred *old_cred; |
1367 | unsigned int i; |
1368 | bool positive = false; |
1369 | bool done = false; |
1370 | |
1371 | /* |
1372 | * If dentry is negative, then lower is positive iff this is a |
1373 | * whiteout. |
1374 | */ |
1375 | if (!dentry->d_inode) |
1376 | return ovl_dentry_is_opaque(dentry); |
1377 | |
1378 | /* Negative upper -> positive lower */ |
1379 | if (!ovl_dentry_upper(dentry)) |
1380 | return true; |
1381 | |
1382 | old_cred = ovl_override_creds(sb: dentry->d_sb); |
1383 | /* Positive upper -> have to look up lower to see whether it exists */ |
1384 | for (i = 0; !done && !positive && i < ovl_numlower(oe: poe); i++) { |
1385 | struct dentry *this; |
1386 | struct ovl_path *parentpath = &ovl_lowerstack(oe: poe)[i]; |
1387 | |
1388 | this = lookup_one_positive_unlocked( |
1389 | idmap: mnt_idmap(mnt: parentpath->layer->mnt), |
1390 | name: name->name, base: parentpath->dentry, len: name->len); |
1391 | if (IS_ERR(ptr: this)) { |
1392 | switch (PTR_ERR(ptr: this)) { |
1393 | case -ENOENT: |
1394 | case -ENAMETOOLONG: |
1395 | break; |
1396 | |
1397 | default: |
1398 | /* |
1399 | * Assume something is there, we just couldn't |
1400 | * access it. |
1401 | */ |
1402 | positive = true; |
1403 | break; |
1404 | } |
1405 | } else { |
1406 | struct path path = { |
1407 | .dentry = this, |
1408 | .mnt = parentpath->layer->mnt, |
1409 | }; |
1410 | positive = !ovl_path_is_whiteout(ofs: OVL_FS(sb: dentry->d_sb), path: &path); |
1411 | done = true; |
1412 | dput(this); |
1413 | } |
1414 | } |
1415 | revert_creds(old_cred); |
1416 | |
1417 | return positive; |
1418 | } |
1419 | |