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 | const struct ovl_layer *layer; |
22 | struct qstr name; |
23 | bool is_dir; |
24 | bool opaque; |
25 | bool xwhiteouts; |
26 | bool stop; |
27 | bool last; |
28 | char *redirect; |
29 | int metacopy; |
30 | /* Referring to last redirect xattr */ |
31 | bool absolute_redirect; |
32 | }; |
33 | |
34 | static int ovl_check_redirect(const struct path *path, struct ovl_lookup_data *d, |
35 | size_t prelen, const char *post) |
36 | { |
37 | int res; |
38 | char *buf; |
39 | struct ovl_fs *ofs = OVL_FS(sb: d->sb); |
40 | |
41 | d->absolute_redirect = false; |
42 | buf = ovl_get_redirect_xattr(ofs, path, padding: prelen + strlen(post)); |
43 | if (IS_ERR_OR_NULL(ptr: buf)) |
44 | return PTR_ERR(ptr: buf); |
45 | |
46 | if (buf[0] == '/') { |
47 | d->absolute_redirect = true; |
48 | /* |
49 | * One of the ancestor path elements in an absolute path |
50 | * lookup in ovl_lookup_layer() could have been opaque and |
51 | * that will stop further lookup in lower layers (d->stop=true) |
52 | * But we have found an absolute redirect in descendant path |
53 | * element and that should force continue lookup in lower |
54 | * layers (reset d->stop). |
55 | */ |
56 | d->stop = false; |
57 | } else { |
58 | res = strlen(buf) + 1; |
59 | memmove(buf + prelen, buf, res); |
60 | memcpy(buf, d->name.name, prelen); |
61 | } |
62 | |
63 | strcat(p: buf, q: post); |
64 | kfree(objp: d->redirect); |
65 | d->redirect = buf; |
66 | d->name.name = d->redirect; |
67 | d->name.len = strlen(d->redirect); |
68 | |
69 | return 0; |
70 | } |
71 | |
72 | static int ovl_acceptable(void *ctx, struct dentry *dentry) |
73 | { |
74 | /* |
75 | * A non-dir origin may be disconnected, which is fine, because |
76 | * we only need it for its unique inode number. |
77 | */ |
78 | if (!d_is_dir(dentry)) |
79 | return 1; |
80 | |
81 | /* Don't decode a deleted empty directory */ |
82 | if (d_unhashed(dentry)) |
83 | return 0; |
84 | |
85 | /* Check if directory belongs to the layer we are decoding from */ |
86 | return is_subdir(dentry, ((struct vfsmount *)ctx)->mnt_root); |
87 | } |
88 | |
89 | /* |
90 | * Check validity of an overlay file handle buffer. |
91 | * |
92 | * Return 0 for a valid file handle. |
93 | * Return -ENODATA for "origin unknown". |
94 | * Return <0 for an invalid file handle. |
95 | */ |
96 | int ovl_check_fb_len(struct ovl_fb *fb, int fb_len) |
97 | { |
98 | if (fb_len < sizeof(struct ovl_fb) || fb_len < fb->len) |
99 | return -EINVAL; |
100 | |
101 | if (fb->magic != OVL_FH_MAGIC) |
102 | return -EINVAL; |
103 | |
104 | /* Treat larger version and unknown flags as "origin unknown" */ |
105 | if (fb->version > OVL_FH_VERSION || fb->flags & ~OVL_FH_FLAG_ALL) |
106 | return -ENODATA; |
107 | |
108 | /* Treat endianness mismatch as "origin unknown" */ |
109 | if (!(fb->flags & OVL_FH_FLAG_ANY_ENDIAN) && |
110 | (fb->flags & OVL_FH_FLAG_BIG_ENDIAN) != OVL_FH_FLAG_CPU_ENDIAN) |
111 | return -ENODATA; |
112 | |
113 | return 0; |
114 | } |
115 | |
116 | static struct ovl_fh *ovl_get_fh(struct ovl_fs *ofs, struct dentry *upperdentry, |
117 | enum ovl_xattr ox) |
118 | { |
119 | int res, err; |
120 | struct ovl_fh *fh = NULL; |
121 | |
122 | res = ovl_getxattr_upper(ofs, upperdentry, ox, NULL, size: 0); |
123 | if (res < 0) { |
124 | if (res == -ENODATA || res == -EOPNOTSUPP) |
125 | return NULL; |
126 | goto fail; |
127 | } |
128 | /* Zero size value means "copied up but origin unknown" */ |
129 | if (res == 0) |
130 | return NULL; |
131 | |
132 | fh = kzalloc(size: res + OVL_FH_WIRE_OFFSET, GFP_KERNEL); |
133 | if (!fh) |
134 | return ERR_PTR(error: -ENOMEM); |
135 | |
136 | res = ovl_getxattr_upper(ofs, upperdentry, ox, value: fh->buf, size: res); |
137 | if (res < 0) |
138 | goto fail; |
139 | |
140 | err = ovl_check_fb_len(fb: &fh->fb, fb_len: res); |
141 | if (err < 0) { |
142 | if (err == -ENODATA) |
143 | goto out; |
144 | goto invalid; |
145 | } |
146 | |
147 | return fh; |
148 | |
149 | out: |
150 | kfree(objp: fh); |
151 | return NULL; |
152 | |
153 | fail: |
154 | pr_warn_ratelimited("failed to get origin (%i)\n" , res); |
155 | goto out; |
156 | invalid: |
157 | pr_warn_ratelimited("invalid origin (%*phN)\n" , res, fh); |
158 | goto out; |
159 | } |
160 | |
161 | struct dentry *ovl_decode_real_fh(struct ovl_fs *ofs, struct ovl_fh *fh, |
162 | struct vfsmount *mnt, bool connected) |
163 | { |
164 | struct dentry *real; |
165 | int bytes; |
166 | |
167 | if (!capable(CAP_DAC_READ_SEARCH)) |
168 | return NULL; |
169 | |
170 | /* |
171 | * Make sure that the stored uuid matches the uuid of the lower |
172 | * layer where file handle will be decoded. |
173 | * In case of uuid=off option just make sure that stored uuid is null. |
174 | */ |
175 | if (ovl_origin_uuid(ofs) ? |
176 | !uuid_equal(u1: &fh->fb.uuid, u2: &mnt->mnt_sb->s_uuid) : |
177 | !uuid_is_null(uuid: &fh->fb.uuid)) |
178 | return NULL; |
179 | |
180 | bytes = (fh->fb.len - offsetof(struct ovl_fb, fid)); |
181 | real = exportfs_decode_fh(mnt, fid: (struct fid *)fh->fb.fid, |
182 | fh_len: bytes >> 2, fileid_type: (int)fh->fb.type, |
183 | acceptable: connected ? ovl_acceptable : NULL, context: mnt); |
184 | if (IS_ERR(ptr: real)) { |
185 | /* |
186 | * Treat stale file handle to lower file as "origin unknown". |
187 | * upper file handle could become stale when upper file is |
188 | * unlinked and this information is needed to handle stale |
189 | * index entries correctly. |
190 | */ |
191 | if (real == ERR_PTR(error: -ESTALE) && |
192 | !(fh->fb.flags & OVL_FH_FLAG_PATH_UPPER)) |
193 | real = NULL; |
194 | return real; |
195 | } |
196 | |
197 | if (ovl_dentry_weird(dentry: real)) { |
198 | dput(real); |
199 | return NULL; |
200 | } |
201 | |
202 | return real; |
203 | } |
204 | |
205 | static struct dentry *ovl_lookup_positive_unlocked(struct ovl_lookup_data *d, |
206 | const char *name, |
207 | struct dentry *base, int len, |
208 | bool drop_negative) |
209 | { |
210 | struct dentry *ret = lookup_one_unlocked(idmap: mnt_idmap(mnt: d->layer->mnt), name, |
211 | base, len); |
212 | |
213 | if (!IS_ERR(ptr: ret) && d_flags_negative(smp_load_acquire(&ret->d_flags))) { |
214 | if (drop_negative && ret->d_lockref.count == 1) { |
215 | spin_lock(lock: &ret->d_lock); |
216 | /* Recheck condition under lock */ |
217 | if (d_is_negative(dentry: ret) && ret->d_lockref.count == 1) |
218 | __d_drop(dentry: ret); |
219 | spin_unlock(lock: &ret->d_lock); |
220 | } |
221 | dput(ret); |
222 | ret = ERR_PTR(error: -ENOENT); |
223 | } |
224 | return ret; |
225 | } |
226 | |
227 | static int ovl_lookup_single(struct dentry *base, struct ovl_lookup_data *d, |
228 | const char *name, unsigned int namelen, |
229 | size_t prelen, const char *post, |
230 | struct dentry **ret, bool drop_negative) |
231 | { |
232 | struct ovl_fs *ofs = OVL_FS(sb: d->sb); |
233 | struct dentry *this; |
234 | struct path path; |
235 | int err; |
236 | bool last_element = !post[0]; |
237 | bool is_upper = d->layer->idx == 0; |
238 | char val; |
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->layer->mnt; |
257 | if (ovl_path_is_whiteout(ofs, 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, 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 | /* overlay.opaque=x means xwhiteouts directory */ |
296 | val = ovl_get_opaquedir_val(ofs, path: &path); |
297 | if (last_element && !is_upper && val == 'x') { |
298 | d->xwhiteouts = true; |
299 | ovl_layer_set_xwhiteouts(ofs, layer: d->layer); |
300 | } else if (val == 'y') { |
301 | d->stop = true; |
302 | if (last_element) |
303 | d->opaque = true; |
304 | goto out; |
305 | } |
306 | } |
307 | err = ovl_check_redirect(path: &path, d, prelen, post); |
308 | if (err) |
309 | goto out_err; |
310 | out: |
311 | *ret = this; |
312 | return 0; |
313 | |
314 | put_and_out: |
315 | dput(this); |
316 | this = NULL; |
317 | goto out; |
318 | |
319 | out_err: |
320 | dput(this); |
321 | return err; |
322 | } |
323 | |
324 | static int ovl_lookup_layer(struct dentry *base, struct ovl_lookup_data *d, |
325 | struct dentry **ret, bool drop_negative) |
326 | { |
327 | /* Counting down from the end, since the prefix can change */ |
328 | size_t rem = d->name.len - 1; |
329 | struct dentry *dentry = NULL; |
330 | int err; |
331 | |
332 | if (d->name.name[0] != '/') |
333 | return ovl_lookup_single(base, d, name: d->name.name, namelen: d->name.len, |
334 | prelen: 0, post: "" , ret, drop_negative); |
335 | |
336 | while (!IS_ERR_OR_NULL(ptr: base) && d_can_lookup(dentry: base)) { |
337 | const char *s = d->name.name + d->name.len - rem; |
338 | const char *next = strchrnul(s, '/'); |
339 | size_t thislen = next - s; |
340 | bool end = !next[0]; |
341 | |
342 | /* Verify we did not go off the rails */ |
343 | if (WARN_ON(s[-1] != '/')) |
344 | return -EIO; |
345 | |
346 | err = ovl_lookup_single(base, d, name: s, namelen: thislen, |
347 | prelen: d->name.len - rem, post: next, ret: &base, |
348 | drop_negative); |
349 | dput(dentry); |
350 | if (err) |
351 | return err; |
352 | dentry = base; |
353 | if (end) |
354 | break; |
355 | |
356 | rem -= thislen + 1; |
357 | |
358 | if (WARN_ON(rem >= d->name.len)) |
359 | return -EIO; |
360 | } |
361 | *ret = dentry; |
362 | return 0; |
363 | } |
364 | |
365 | static int ovl_lookup_data_layer(struct dentry *dentry, const char *redirect, |
366 | const struct ovl_layer *layer, |
367 | struct path *datapath) |
368 | { |
369 | int err; |
370 | |
371 | err = vfs_path_lookup(layer->mnt->mnt_root, layer->mnt, redirect, |
372 | LOOKUP_BENEATH | LOOKUP_NO_SYMLINKS | LOOKUP_NO_XDEV, |
373 | datapath); |
374 | pr_debug("lookup lowerdata (%pd2, redirect=\"%s\", layer=%d, err=%i)\n" , |
375 | dentry, redirect, layer->idx, err); |
376 | |
377 | if (err) |
378 | return err; |
379 | |
380 | err = -EREMOTE; |
381 | if (ovl_dentry_weird(dentry: datapath->dentry)) |
382 | goto out_path_put; |
383 | |
384 | err = -ENOENT; |
385 | /* Only regular file is acceptable as lower data */ |
386 | if (!d_is_reg(dentry: datapath->dentry)) |
387 | goto out_path_put; |
388 | |
389 | return 0; |
390 | |
391 | out_path_put: |
392 | path_put(datapath); |
393 | |
394 | return err; |
395 | } |
396 | |
397 | /* Lookup in data-only layers by absolute redirect to layer root */ |
398 | static int ovl_lookup_data_layers(struct dentry *dentry, const char *redirect, |
399 | struct ovl_path *lowerdata) |
400 | { |
401 | struct ovl_fs *ofs = OVL_FS(sb: dentry->d_sb); |
402 | const struct ovl_layer *layer; |
403 | struct path datapath; |
404 | int err = -ENOENT; |
405 | int i; |
406 | |
407 | layer = &ofs->layers[ofs->numlayer - ofs->numdatalayer]; |
408 | for (i = 0; i < ofs->numdatalayer; i++, layer++) { |
409 | err = ovl_lookup_data_layer(dentry, redirect, layer, datapath: &datapath); |
410 | if (!err) { |
411 | mntput(mnt: datapath.mnt); |
412 | lowerdata->dentry = datapath.dentry; |
413 | lowerdata->layer = layer; |
414 | return 0; |
415 | } |
416 | } |
417 | |
418 | return err; |
419 | } |
420 | |
421 | int ovl_check_origin_fh(struct ovl_fs *ofs, struct ovl_fh *fh, bool connected, |
422 | struct dentry *upperdentry, struct ovl_path **stackp) |
423 | { |
424 | struct dentry *origin = NULL; |
425 | int i; |
426 | |
427 | for (i = 1; i <= ovl_numlowerlayer(ofs); i++) { |
428 | /* |
429 | * If lower fs uuid is not unique among lower fs we cannot match |
430 | * fh->uuid to layer. |
431 | */ |
432 | if (ofs->layers[i].fsid && |
433 | ofs->layers[i].fs->bad_uuid) |
434 | continue; |
435 | |
436 | origin = ovl_decode_real_fh(ofs, fh, mnt: ofs->layers[i].mnt, |
437 | connected); |
438 | if (origin) |
439 | break; |
440 | } |
441 | |
442 | if (!origin) |
443 | return -ESTALE; |
444 | else if (IS_ERR(ptr: origin)) |
445 | return PTR_ERR(ptr: origin); |
446 | |
447 | if (upperdentry && !ovl_upper_is_whiteout(ofs, upperdentry) && |
448 | inode_wrong_type(inode: d_inode(dentry: upperdentry), mode: d_inode(dentry: origin)->i_mode)) |
449 | goto invalid; |
450 | |
451 | if (!*stackp) |
452 | *stackp = kmalloc(size: sizeof(struct ovl_path), GFP_KERNEL); |
453 | if (!*stackp) { |
454 | dput(origin); |
455 | return -ENOMEM; |
456 | } |
457 | **stackp = (struct ovl_path){ |
458 | .dentry = origin, |
459 | .layer = &ofs->layers[i] |
460 | }; |
461 | |
462 | return 0; |
463 | |
464 | invalid: |
465 | pr_warn_ratelimited("invalid origin (%pd2, ftype=%x, origin ftype=%x).\n" , |
466 | upperdentry, d_inode(upperdentry)->i_mode & S_IFMT, |
467 | d_inode(origin)->i_mode & S_IFMT); |
468 | dput(origin); |
469 | return -ESTALE; |
470 | } |
471 | |
472 | static int ovl_check_origin(struct ovl_fs *ofs, struct dentry *upperdentry, |
473 | struct ovl_path **stackp) |
474 | { |
475 | struct ovl_fh *fh = ovl_get_fh(ofs, upperdentry, ox: OVL_XATTR_ORIGIN); |
476 | int err; |
477 | |
478 | if (IS_ERR_OR_NULL(ptr: fh)) |
479 | return PTR_ERR(ptr: fh); |
480 | |
481 | err = ovl_check_origin_fh(ofs, fh, connected: false, upperdentry, stackp); |
482 | kfree(objp: fh); |
483 | |
484 | if (err) { |
485 | if (err == -ESTALE) |
486 | return 0; |
487 | return err; |
488 | } |
489 | |
490 | return 0; |
491 | } |
492 | |
493 | /* |
494 | * Verify that @fh matches the file handle stored in xattr @name. |
495 | * Return 0 on match, -ESTALE on mismatch, < 0 on error. |
496 | */ |
497 | static int ovl_verify_fh(struct ovl_fs *ofs, struct dentry *dentry, |
498 | enum ovl_xattr ox, const struct ovl_fh *fh) |
499 | { |
500 | struct ovl_fh *ofh = ovl_get_fh(ofs, upperdentry: dentry, ox); |
501 | int err = 0; |
502 | |
503 | if (!ofh) |
504 | return -ENODATA; |
505 | |
506 | if (IS_ERR(ptr: ofh)) |
507 | return PTR_ERR(ptr: ofh); |
508 | |
509 | if (fh->fb.len != ofh->fb.len || memcmp(p: &fh->fb, q: &ofh->fb, size: fh->fb.len)) |
510 | err = -ESTALE; |
511 | |
512 | kfree(objp: ofh); |
513 | return err; |
514 | } |
515 | |
516 | int ovl_verify_set_fh(struct ovl_fs *ofs, struct dentry *dentry, |
517 | enum ovl_xattr ox, const struct ovl_fh *fh, |
518 | bool is_upper, bool set) |
519 | { |
520 | int err; |
521 | |
522 | err = ovl_verify_fh(ofs, dentry, ox, fh); |
523 | if (set && err == -ENODATA) |
524 | err = ovl_setxattr(ofs, dentry, ox, value: fh->buf, size: fh->fb.len); |
525 | |
526 | return err; |
527 | } |
528 | |
529 | /* |
530 | * Verify that @real dentry matches the file handle stored in xattr @name. |
531 | * |
532 | * If @set is true and there is no stored file handle, encode @real and store |
533 | * file handle in xattr @name. |
534 | * |
535 | * Return 0 on match, -ESTALE on mismatch, -ENODATA on no xattr, < 0 on error. |
536 | */ |
537 | int ovl_verify_origin_xattr(struct ovl_fs *ofs, struct dentry *dentry, |
538 | enum ovl_xattr ox, struct dentry *real, |
539 | bool is_upper, bool set) |
540 | { |
541 | struct inode *inode; |
542 | struct ovl_fh *fh; |
543 | int err; |
544 | |
545 | fh = ovl_encode_real_fh(ofs, real, is_upper); |
546 | err = PTR_ERR(ptr: fh); |
547 | if (IS_ERR(ptr: fh)) { |
548 | fh = NULL; |
549 | goto fail; |
550 | } |
551 | |
552 | err = ovl_verify_set_fh(ofs, dentry, ox, fh, is_upper, set); |
553 | if (err) |
554 | goto fail; |
555 | |
556 | out: |
557 | kfree(objp: fh); |
558 | return err; |
559 | |
560 | fail: |
561 | inode = d_inode(dentry: real); |
562 | pr_warn_ratelimited("failed to verify %s (%pd2, ino=%lu, err=%i)\n" , |
563 | is_upper ? "upper" : "origin" , real, |
564 | inode ? inode->i_ino : 0, err); |
565 | goto out; |
566 | } |
567 | |
568 | |
569 | /* Get upper dentry from index */ |
570 | struct dentry *ovl_index_upper(struct ovl_fs *ofs, struct dentry *index, |
571 | bool connected) |
572 | { |
573 | struct ovl_fh *fh; |
574 | struct dentry *upper; |
575 | |
576 | if (!d_is_dir(dentry: index)) |
577 | return dget(dentry: index); |
578 | |
579 | fh = ovl_get_fh(ofs, upperdentry: index, ox: OVL_XATTR_UPPER); |
580 | if (IS_ERR_OR_NULL(ptr: fh)) |
581 | return ERR_CAST(ptr: fh); |
582 | |
583 | upper = ovl_decode_real_fh(ofs, fh, mnt: ovl_upper_mnt(ofs), connected); |
584 | kfree(objp: fh); |
585 | |
586 | if (IS_ERR_OR_NULL(ptr: upper)) |
587 | return upper ?: ERR_PTR(error: -ESTALE); |
588 | |
589 | if (!d_is_dir(dentry: upper)) { |
590 | pr_warn_ratelimited("invalid index upper (%pd2, upper=%pd2).\n" , |
591 | index, upper); |
592 | dput(upper); |
593 | return ERR_PTR(error: -EIO); |
594 | } |
595 | |
596 | return upper; |
597 | } |
598 | |
599 | /* |
600 | * Verify that an index entry name matches the origin file handle stored in |
601 | * OVL_XATTR_ORIGIN and that origin file handle can be decoded to lower path. |
602 | * Return 0 on match, -ESTALE on mismatch or stale origin, < 0 on error. |
603 | */ |
604 | int ovl_verify_index(struct ovl_fs *ofs, struct dentry *index) |
605 | { |
606 | struct ovl_fh *fh = NULL; |
607 | size_t len; |
608 | struct ovl_path origin = { }; |
609 | struct ovl_path *stack = &origin; |
610 | struct dentry *upper = NULL; |
611 | int err; |
612 | |
613 | if (!d_inode(dentry: index)) |
614 | return 0; |
615 | |
616 | err = -EINVAL; |
617 | if (index->d_name.len < sizeof(struct ovl_fb)*2) |
618 | goto fail; |
619 | |
620 | err = -ENOMEM; |
621 | len = index->d_name.len / 2; |
622 | fh = kzalloc(size: len + OVL_FH_WIRE_OFFSET, GFP_KERNEL); |
623 | if (!fh) |
624 | goto fail; |
625 | |
626 | err = -EINVAL; |
627 | if (hex2bin(dst: fh->buf, src: index->d_name.name, count: len)) |
628 | goto fail; |
629 | |
630 | err = ovl_check_fb_len(fb: &fh->fb, fb_len: len); |
631 | if (err) |
632 | goto fail; |
633 | |
634 | /* |
635 | * Whiteout index entries are used as an indication that an exported |
636 | * overlay file handle should be treated as stale (i.e. after unlink |
637 | * of the overlay inode). These entries contain no origin xattr. |
638 | */ |
639 | if (ovl_is_whiteout(dentry: index)) |
640 | goto out; |
641 | |
642 | /* |
643 | * Verifying directory index entries are not stale is expensive, so |
644 | * only verify stale dir index if NFS export is enabled. |
645 | */ |
646 | if (d_is_dir(dentry: index) && !ofs->config.nfs_export) |
647 | goto out; |
648 | |
649 | /* |
650 | * Directory index entries should have 'upper' xattr pointing to the |
651 | * real upper dir. Non-dir index entries are hardlinks to the upper |
652 | * real inode. For non-dir index, we can read the copy up origin xattr |
653 | * directly from the index dentry, but for dir index we first need to |
654 | * decode the upper directory. |
655 | */ |
656 | upper = ovl_index_upper(ofs, index, connected: false); |
657 | if (IS_ERR_OR_NULL(ptr: upper)) { |
658 | err = PTR_ERR(ptr: upper); |
659 | /* |
660 | * Directory index entries with no 'upper' xattr need to be |
661 | * removed. When dir index entry has a stale 'upper' xattr, |
662 | * we assume that upper dir was removed and we treat the dir |
663 | * index as orphan entry that needs to be whited out. |
664 | */ |
665 | if (err == -ESTALE) |
666 | goto orphan; |
667 | else if (!err) |
668 | err = -ESTALE; |
669 | goto fail; |
670 | } |
671 | |
672 | err = ovl_verify_fh(ofs, dentry: upper, ox: OVL_XATTR_ORIGIN, fh); |
673 | dput(upper); |
674 | if (err) |
675 | goto fail; |
676 | |
677 | /* Check if non-dir index is orphan and don't warn before cleaning it */ |
678 | if (!d_is_dir(dentry: index) && d_inode(dentry: index)->i_nlink == 1) { |
679 | err = ovl_check_origin_fh(ofs, fh, connected: false, upperdentry: index, stackp: &stack); |
680 | if (err) |
681 | goto fail; |
682 | |
683 | if (ovl_get_nlink(ofs, lowerdentry: origin.dentry, upperdentry: index, fallback: 0) == 0) |
684 | goto orphan; |
685 | } |
686 | |
687 | out: |
688 | dput(origin.dentry); |
689 | kfree(objp: fh); |
690 | return err; |
691 | |
692 | fail: |
693 | pr_warn_ratelimited("failed to verify index (%pd2, ftype=%x, err=%i)\n" , |
694 | index, d_inode(index)->i_mode & S_IFMT, err); |
695 | goto out; |
696 | |
697 | orphan: |
698 | pr_warn_ratelimited("orphan index entry (%pd2, ftype=%x, nlink=%u)\n" , |
699 | index, d_inode(index)->i_mode & S_IFMT, |
700 | d_inode(index)->i_nlink); |
701 | err = -ENOENT; |
702 | goto out; |
703 | } |
704 | |
705 | int ovl_get_index_name_fh(const struct ovl_fh *fh, struct qstr *name) |
706 | { |
707 | char *n, *s; |
708 | |
709 | n = kcalloc(n: fh->fb.len, size: 2, GFP_KERNEL); |
710 | if (!n) |
711 | return -ENOMEM; |
712 | |
713 | s = bin2hex(dst: n, src: fh->buf, count: fh->fb.len); |
714 | *name = (struct qstr) QSTR_INIT(n, s - n); |
715 | |
716 | return 0; |
717 | |
718 | } |
719 | |
720 | /* |
721 | * Lookup in indexdir for the index entry of a lower real inode or a copy up |
722 | * origin inode. The index entry name is the hex representation of the lower |
723 | * inode file handle. |
724 | * |
725 | * If the index dentry in negative, then either no lower aliases have been |
726 | * copied up yet, or aliases have been copied up in older kernels and are |
727 | * not indexed. |
728 | * |
729 | * If the index dentry for a copy up origin inode is positive, but points |
730 | * to an inode different than the upper inode, then either the upper inode |
731 | * has been copied up and not indexed or it was indexed, but since then |
732 | * index dir was cleared. Either way, that index cannot be used to identify |
733 | * the overlay inode. |
734 | */ |
735 | int ovl_get_index_name(struct ovl_fs *ofs, struct dentry *origin, |
736 | struct qstr *name) |
737 | { |
738 | struct ovl_fh *fh; |
739 | int err; |
740 | |
741 | fh = ovl_encode_real_fh(ofs, real: origin, is_upper: false); |
742 | if (IS_ERR(ptr: fh)) |
743 | return PTR_ERR(ptr: fh); |
744 | |
745 | err = ovl_get_index_name_fh(fh, name); |
746 | |
747 | kfree(objp: fh); |
748 | return err; |
749 | } |
750 | |
751 | /* Lookup index by file handle for NFS export */ |
752 | struct dentry *ovl_get_index_fh(struct ovl_fs *ofs, struct ovl_fh *fh) |
753 | { |
754 | struct dentry *index; |
755 | struct qstr name; |
756 | int err; |
757 | |
758 | err = ovl_get_index_name_fh(fh, name: &name); |
759 | if (err) |
760 | return ERR_PTR(error: err); |
761 | |
762 | index = lookup_positive_unlocked(name.name, ofs->workdir, name.len); |
763 | kfree(objp: name.name); |
764 | if (IS_ERR(ptr: index)) { |
765 | if (PTR_ERR(ptr: index) == -ENOENT) |
766 | index = NULL; |
767 | return index; |
768 | } |
769 | |
770 | if (ovl_is_whiteout(dentry: index)) |
771 | err = -ESTALE; |
772 | else if (ovl_dentry_weird(dentry: index)) |
773 | err = -EIO; |
774 | else |
775 | return index; |
776 | |
777 | dput(index); |
778 | return ERR_PTR(error: err); |
779 | } |
780 | |
781 | struct dentry *ovl_lookup_index(struct ovl_fs *ofs, struct dentry *upper, |
782 | struct dentry *origin, bool verify) |
783 | { |
784 | struct dentry *index; |
785 | struct inode *inode; |
786 | struct qstr name; |
787 | bool is_dir = d_is_dir(dentry: origin); |
788 | int err; |
789 | |
790 | err = ovl_get_index_name(ofs, origin, name: &name); |
791 | if (err) |
792 | return ERR_PTR(error: err); |
793 | |
794 | index = lookup_one_positive_unlocked(idmap: ovl_upper_mnt_idmap(ofs), name: name.name, |
795 | base: ofs->workdir, len: name.len); |
796 | if (IS_ERR(ptr: index)) { |
797 | err = PTR_ERR(ptr: index); |
798 | if (err == -ENOENT) { |
799 | index = NULL; |
800 | goto out; |
801 | } |
802 | pr_warn_ratelimited("failed inode index lookup (ino=%lu, key=%.*s, err=%i);\n" |
803 | "overlayfs: mount with '-o index=off' to disable inodes index.\n" , |
804 | d_inode(origin)->i_ino, name.len, name.name, |
805 | err); |
806 | goto out; |
807 | } |
808 | |
809 | inode = d_inode(dentry: index); |
810 | if (ovl_is_whiteout(dentry: index) && !verify) { |
811 | /* |
812 | * When index lookup is called with !verify for decoding an |
813 | * overlay file handle, a whiteout index implies that decode |
814 | * should treat file handle as stale and no need to print a |
815 | * warning about it. |
816 | */ |
817 | dput(index); |
818 | index = ERR_PTR(error: -ESTALE); |
819 | goto out; |
820 | } else if (ovl_dentry_weird(dentry: index) || ovl_is_whiteout(dentry: index) || |
821 | inode_wrong_type(inode, mode: d_inode(dentry: origin)->i_mode)) { |
822 | /* |
823 | * Index should always be of the same file type as origin |
824 | * except for the case of a whiteout index. A whiteout |
825 | * index should only exist if all lower aliases have been |
826 | * unlinked, which means that finding a lower origin on lookup |
827 | * whose index is a whiteout should be treated as an error. |
828 | */ |
829 | pr_warn_ratelimited("bad index found (index=%pd2, ftype=%x, origin ftype=%x).\n" , |
830 | index, d_inode(index)->i_mode & S_IFMT, |
831 | d_inode(origin)->i_mode & S_IFMT); |
832 | goto fail; |
833 | } else if (is_dir && verify) { |
834 | if (!upper) { |
835 | pr_warn_ratelimited("suspected uncovered redirected dir found (origin=%pd2, index=%pd2).\n" , |
836 | origin, index); |
837 | goto fail; |
838 | } |
839 | |
840 | /* Verify that dir index 'upper' xattr points to upper dir */ |
841 | err = ovl_verify_upper(ofs, index, upper, set: false); |
842 | if (err) { |
843 | if (err == -ESTALE) { |
844 | pr_warn_ratelimited("suspected multiply redirected dir found (upper=%pd2, origin=%pd2, index=%pd2).\n" , |
845 | upper, origin, index); |
846 | } |
847 | goto fail; |
848 | } |
849 | } else if (upper && d_inode(dentry: upper) != inode) { |
850 | goto out_dput; |
851 | } |
852 | out: |
853 | kfree(objp: name.name); |
854 | return index; |
855 | |
856 | out_dput: |
857 | dput(index); |
858 | index = NULL; |
859 | goto out; |
860 | |
861 | fail: |
862 | dput(index); |
863 | index = ERR_PTR(error: -EIO); |
864 | goto out; |
865 | } |
866 | |
867 | /* |
868 | * Returns next layer in stack starting from top. |
869 | * Returns -1 if this is the last layer. |
870 | */ |
871 | int ovl_path_next(int idx, struct dentry *dentry, struct path *path, |
872 | const struct ovl_layer **layer) |
873 | { |
874 | struct ovl_entry *oe = OVL_E(dentry); |
875 | struct ovl_path *lowerstack = ovl_lowerstack(oe); |
876 | |
877 | BUG_ON(idx < 0); |
878 | if (idx == 0) { |
879 | ovl_path_upper(dentry, path); |
880 | if (path->dentry) { |
881 | *layer = &OVL_FS(sb: dentry->d_sb)->layers[0]; |
882 | return ovl_numlower(oe) ? 1 : -1; |
883 | } |
884 | idx++; |
885 | } |
886 | BUG_ON(idx > ovl_numlower(oe)); |
887 | path->dentry = lowerstack[idx - 1].dentry; |
888 | *layer = lowerstack[idx - 1].layer; |
889 | path->mnt = (*layer)->mnt; |
890 | |
891 | return (idx < ovl_numlower(oe)) ? idx + 1 : -1; |
892 | } |
893 | |
894 | /* Fix missing 'origin' xattr */ |
895 | static int ovl_fix_origin(struct ovl_fs *ofs, struct dentry *dentry, |
896 | struct dentry *lower, struct dentry *upper) |
897 | { |
898 | const struct ovl_fh *fh; |
899 | int err; |
900 | |
901 | if (ovl_check_origin_xattr(ofs, upperdentry: upper)) |
902 | return 0; |
903 | |
904 | fh = ovl_get_origin_fh(ofs, origin: lower); |
905 | if (IS_ERR(ptr: fh)) |
906 | return PTR_ERR(ptr: fh); |
907 | |
908 | err = ovl_want_write(dentry); |
909 | if (err) |
910 | goto out; |
911 | |
912 | err = ovl_set_origin_fh(ofs, fh, upper); |
913 | if (!err) |
914 | err = ovl_set_impure(dentry: dentry->d_parent, upperdentry: upper->d_parent); |
915 | |
916 | ovl_drop_write(dentry); |
917 | out: |
918 | kfree(objp: fh); |
919 | return err; |
920 | } |
921 | |
922 | static int ovl_maybe_validate_verity(struct dentry *dentry) |
923 | { |
924 | struct ovl_fs *ofs = OVL_FS(sb: dentry->d_sb); |
925 | struct inode *inode = d_inode(dentry); |
926 | struct path datapath, metapath; |
927 | int err; |
928 | |
929 | if (!ofs->config.verity_mode || |
930 | !ovl_is_metacopy_dentry(dentry) || |
931 | ovl_test_flag(flag: OVL_VERIFIED_DIGEST, inode)) |
932 | return 0; |
933 | |
934 | if (!ovl_test_flag(flag: OVL_HAS_DIGEST, inode)) { |
935 | if (ofs->config.verity_mode == OVL_VERITY_REQUIRE) { |
936 | pr_warn_ratelimited("metacopy file '%pd' has no digest specified\n" , |
937 | dentry); |
938 | return -EIO; |
939 | } |
940 | return 0; |
941 | } |
942 | |
943 | ovl_path_lowerdata(dentry, path: &datapath); |
944 | if (!datapath.dentry) |
945 | return -EIO; |
946 | |
947 | ovl_path_real(dentry, path: &metapath); |
948 | if (!metapath.dentry) |
949 | return -EIO; |
950 | |
951 | err = ovl_inode_lock_interruptible(inode); |
952 | if (err) |
953 | return err; |
954 | |
955 | if (!ovl_test_flag(flag: OVL_VERIFIED_DIGEST, inode)) { |
956 | const struct cred *old_cred; |
957 | |
958 | old_cred = ovl_override_creds(sb: dentry->d_sb); |
959 | |
960 | err = ovl_validate_verity(ofs, metapath: &metapath, datapath: &datapath); |
961 | if (err == 0) |
962 | ovl_set_flag(flag: OVL_VERIFIED_DIGEST, inode); |
963 | |
964 | revert_creds(old_cred); |
965 | } |
966 | |
967 | ovl_inode_unlock(inode); |
968 | |
969 | return err; |
970 | } |
971 | |
972 | /* Lazy lookup of lowerdata */ |
973 | static int ovl_maybe_lookup_lowerdata(struct dentry *dentry) |
974 | { |
975 | struct inode *inode = d_inode(dentry); |
976 | const char *redirect = ovl_lowerdata_redirect(inode); |
977 | struct ovl_path datapath = {}; |
978 | const struct cred *old_cred; |
979 | int err; |
980 | |
981 | if (!redirect || ovl_dentry_lowerdata(dentry)) |
982 | return 0; |
983 | |
984 | if (redirect[0] != '/') |
985 | return -EIO; |
986 | |
987 | err = ovl_inode_lock_interruptible(inode); |
988 | if (err) |
989 | return err; |
990 | |
991 | err = 0; |
992 | /* Someone got here before us? */ |
993 | if (ovl_dentry_lowerdata(dentry)) |
994 | goto out; |
995 | |
996 | old_cred = ovl_override_creds(sb: dentry->d_sb); |
997 | err = ovl_lookup_data_layers(dentry, redirect, lowerdata: &datapath); |
998 | revert_creds(old_cred); |
999 | if (err) |
1000 | goto out_err; |
1001 | |
1002 | err = ovl_dentry_set_lowerdata(dentry, datapath: &datapath); |
1003 | if (err) |
1004 | goto out_err; |
1005 | |
1006 | out: |
1007 | ovl_inode_unlock(inode); |
1008 | dput(datapath.dentry); |
1009 | |
1010 | return err; |
1011 | |
1012 | out_err: |
1013 | pr_warn_ratelimited("lazy lowerdata lookup failed (%pd2, err=%i)\n" , |
1014 | dentry, err); |
1015 | goto out; |
1016 | } |
1017 | |
1018 | int ovl_verify_lowerdata(struct dentry *dentry) |
1019 | { |
1020 | int err; |
1021 | |
1022 | err = ovl_maybe_lookup_lowerdata(dentry); |
1023 | if (err) |
1024 | return err; |
1025 | |
1026 | return ovl_maybe_validate_verity(dentry); |
1027 | } |
1028 | |
1029 | struct dentry *ovl_lookup(struct inode *dir, struct dentry *dentry, |
1030 | unsigned int flags) |
1031 | { |
1032 | struct ovl_entry *oe = NULL; |
1033 | const struct cred *old_cred; |
1034 | struct ovl_fs *ofs = OVL_FS(sb: dentry->d_sb); |
1035 | struct ovl_entry *poe = OVL_E(dentry: dentry->d_parent); |
1036 | struct ovl_entry *roe = OVL_E(dentry: dentry->d_sb->s_root); |
1037 | struct ovl_path *stack = NULL, *origin_path = NULL; |
1038 | struct dentry *upperdir, *upperdentry = NULL; |
1039 | struct dentry *origin = NULL; |
1040 | struct dentry *index = NULL; |
1041 | unsigned int ctr = 0; |
1042 | struct inode *inode = NULL; |
1043 | bool upperopaque = false; |
1044 | char *upperredirect = NULL; |
1045 | struct dentry *this; |
1046 | unsigned int i; |
1047 | int err; |
1048 | bool uppermetacopy = false; |
1049 | int metacopy_size = 0; |
1050 | struct ovl_lookup_data d = { |
1051 | .sb = dentry->d_sb, |
1052 | .name = dentry->d_name, |
1053 | .is_dir = false, |
1054 | .opaque = false, |
1055 | .stop = false, |
1056 | .last = ovl_redirect_follow(ofs) ? false : !ovl_numlower(oe: poe), |
1057 | .redirect = NULL, |
1058 | .metacopy = 0, |
1059 | }; |
1060 | |
1061 | if (dentry->d_name.len > ofs->namelen) |
1062 | return ERR_PTR(error: -ENAMETOOLONG); |
1063 | |
1064 | old_cred = ovl_override_creds(sb: dentry->d_sb); |
1065 | upperdir = ovl_dentry_upper(dentry: dentry->d_parent); |
1066 | if (upperdir) { |
1067 | d.layer = &ofs->layers[0]; |
1068 | err = ovl_lookup_layer(base: upperdir, d: &d, ret: &upperdentry, drop_negative: true); |
1069 | if (err) |
1070 | goto out; |
1071 | |
1072 | if (upperdentry && upperdentry->d_flags & DCACHE_OP_REAL) { |
1073 | dput(upperdentry); |
1074 | err = -EREMOTE; |
1075 | goto out; |
1076 | } |
1077 | if (upperdentry && !d.is_dir) { |
1078 | /* |
1079 | * Lookup copy up origin by decoding origin file handle. |
1080 | * We may get a disconnected dentry, which is fine, |
1081 | * because we only need to hold the origin inode in |
1082 | * cache and use its inode number. We may even get a |
1083 | * connected dentry, that is not under any of the lower |
1084 | * layers root. That is also fine for using it's inode |
1085 | * number - it's the same as if we held a reference |
1086 | * to a dentry in lower layer that was moved under us. |
1087 | */ |
1088 | err = ovl_check_origin(ofs, upperdentry, stackp: &origin_path); |
1089 | if (err) |
1090 | goto out_put_upper; |
1091 | |
1092 | if (d.metacopy) |
1093 | uppermetacopy = true; |
1094 | metacopy_size = d.metacopy; |
1095 | } |
1096 | |
1097 | if (d.redirect) { |
1098 | err = -ENOMEM; |
1099 | upperredirect = kstrdup(s: d.redirect, GFP_KERNEL); |
1100 | if (!upperredirect) |
1101 | goto out_put_upper; |
1102 | if (d.redirect[0] == '/') |
1103 | poe = roe; |
1104 | } |
1105 | upperopaque = d.opaque; |
1106 | } |
1107 | |
1108 | if (!d.stop && ovl_numlower(oe: poe)) { |
1109 | err = -ENOMEM; |
1110 | stack = ovl_stack_alloc(n: ofs->numlayer - 1); |
1111 | if (!stack) |
1112 | goto out_put_upper; |
1113 | } |
1114 | |
1115 | for (i = 0; !d.stop && i < ovl_numlower(oe: poe); i++) { |
1116 | struct ovl_path lower = ovl_lowerstack(oe: poe)[i]; |
1117 | |
1118 | if (!ovl_redirect_follow(ofs)) |
1119 | d.last = i == ovl_numlower(oe: poe) - 1; |
1120 | else if (d.is_dir || !ofs->numdatalayer) |
1121 | d.last = lower.layer->idx == ovl_numlower(oe: roe); |
1122 | |
1123 | d.layer = lower.layer; |
1124 | err = ovl_lookup_layer(base: lower.dentry, d: &d, ret: &this, drop_negative: false); |
1125 | if (err) |
1126 | goto out_put; |
1127 | |
1128 | if (!this) |
1129 | continue; |
1130 | |
1131 | if ((uppermetacopy || d.metacopy) && !ofs->config.metacopy) { |
1132 | dput(this); |
1133 | err = -EPERM; |
1134 | pr_warn_ratelimited("refusing to follow metacopy origin for (%pd2)\n" , dentry); |
1135 | goto out_put; |
1136 | } |
1137 | |
1138 | /* |
1139 | * If no origin fh is stored in upper of a merge dir, store fh |
1140 | * of lower dir and set upper parent "impure". |
1141 | */ |
1142 | if (upperdentry && !ctr && !ofs->noxattr && d.is_dir) { |
1143 | err = ovl_fix_origin(ofs, dentry, lower: this, upper: upperdentry); |
1144 | if (err) { |
1145 | dput(this); |
1146 | goto out_put; |
1147 | } |
1148 | } |
1149 | |
1150 | /* |
1151 | * When "verify_lower" feature is enabled, do not merge with a |
1152 | * lower dir that does not match a stored origin xattr. In any |
1153 | * case, only verified origin is used for index lookup. |
1154 | * |
1155 | * For non-dir dentry, if index=on, then ensure origin |
1156 | * matches the dentry found using path based lookup, |
1157 | * otherwise error out. |
1158 | */ |
1159 | if (upperdentry && !ctr && |
1160 | ((d.is_dir && ovl_verify_lower(sb: dentry->d_sb)) || |
1161 | (!d.is_dir && ofs->config.index && origin_path))) { |
1162 | err = ovl_verify_origin(ofs, upper: upperdentry, origin: this, set: false); |
1163 | if (err) { |
1164 | dput(this); |
1165 | if (d.is_dir) |
1166 | break; |
1167 | goto out_put; |
1168 | } |
1169 | origin = this; |
1170 | } |
1171 | |
1172 | if (!upperdentry && !d.is_dir && !ctr && d.metacopy) |
1173 | metacopy_size = d.metacopy; |
1174 | |
1175 | if (d.metacopy && ctr) { |
1176 | /* |
1177 | * Do not store intermediate metacopy dentries in |
1178 | * lower chain, except top most lower metacopy dentry. |
1179 | * Continue the loop so that if there is an absolute |
1180 | * redirect on this dentry, poe can be reset to roe. |
1181 | */ |
1182 | dput(this); |
1183 | this = NULL; |
1184 | } else { |
1185 | stack[ctr].dentry = this; |
1186 | stack[ctr].layer = lower.layer; |
1187 | ctr++; |
1188 | } |
1189 | |
1190 | /* |
1191 | * Following redirects can have security consequences: it's like |
1192 | * a symlink into the lower layer without the permission checks. |
1193 | * This is only a problem if the upper layer is untrusted (e.g |
1194 | * comes from an USB drive). This can allow a non-readable file |
1195 | * or directory to become readable. |
1196 | * |
1197 | * Only following redirects when redirects are enabled disables |
1198 | * this attack vector when not necessary. |
1199 | */ |
1200 | err = -EPERM; |
1201 | if (d.redirect && !ovl_redirect_follow(ofs)) { |
1202 | pr_warn_ratelimited("refusing to follow redirect for (%pd2)\n" , |
1203 | dentry); |
1204 | goto out_put; |
1205 | } |
1206 | |
1207 | if (d.stop) |
1208 | break; |
1209 | |
1210 | if (d.redirect && d.redirect[0] == '/' && poe != roe) { |
1211 | poe = roe; |
1212 | /* Find the current layer on the root dentry */ |
1213 | i = lower.layer->idx - 1; |
1214 | } |
1215 | } |
1216 | |
1217 | /* Defer lookup of lowerdata in data-only layers to first access */ |
1218 | if (d.metacopy && ctr && ofs->numdatalayer && d.absolute_redirect) { |
1219 | d.metacopy = 0; |
1220 | ctr++; |
1221 | } |
1222 | |
1223 | /* |
1224 | * For regular non-metacopy upper dentries, there is no lower |
1225 | * path based lookup, hence ctr will be zero. If a dentry is found |
1226 | * using ORIGIN xattr on upper, install it in stack. |
1227 | * |
1228 | * For metacopy dentry, path based lookup will find lower dentries. |
1229 | * Just make sure a corresponding data dentry has been found. |
1230 | */ |
1231 | if (d.metacopy || (uppermetacopy && !ctr)) { |
1232 | pr_warn_ratelimited("metacopy with no lower data found - abort lookup (%pd2)\n" , |
1233 | dentry); |
1234 | err = -EIO; |
1235 | goto out_put; |
1236 | } else if (!d.is_dir && upperdentry && !ctr && origin_path) { |
1237 | if (WARN_ON(stack != NULL)) { |
1238 | err = -EIO; |
1239 | goto out_put; |
1240 | } |
1241 | stack = origin_path; |
1242 | ctr = 1; |
1243 | origin = origin_path->dentry; |
1244 | origin_path = NULL; |
1245 | } |
1246 | |
1247 | /* |
1248 | * Always lookup index if there is no-upperdentry. |
1249 | * |
1250 | * For the case of upperdentry, we have set origin by now if it |
1251 | * needed to be set. There are basically three cases. |
1252 | * |
1253 | * For directories, lookup index by lower inode and verify it matches |
1254 | * upper inode. We only trust dir index if we verified that lower dir |
1255 | * matches origin, otherwise dir index entries may be inconsistent |
1256 | * and we ignore them. |
1257 | * |
1258 | * For regular upper, we already set origin if upper had ORIGIN |
1259 | * xattr. There is no verification though as there is no path |
1260 | * based dentry lookup in lower in this case. |
1261 | * |
1262 | * For metacopy upper, we set a verified origin already if index |
1263 | * is enabled and if upper had an ORIGIN xattr. |
1264 | * |
1265 | */ |
1266 | if (!upperdentry && ctr) |
1267 | origin = stack[0].dentry; |
1268 | |
1269 | if (origin && ovl_indexdir(sb: dentry->d_sb) && |
1270 | (!d.is_dir || ovl_index_all(sb: dentry->d_sb))) { |
1271 | index = ovl_lookup_index(ofs, upper: upperdentry, origin, verify: true); |
1272 | if (IS_ERR(ptr: index)) { |
1273 | err = PTR_ERR(ptr: index); |
1274 | index = NULL; |
1275 | goto out_put; |
1276 | } |
1277 | } |
1278 | |
1279 | if (ctr) { |
1280 | oe = ovl_alloc_entry(numlower: ctr); |
1281 | err = -ENOMEM; |
1282 | if (!oe) |
1283 | goto out_put; |
1284 | |
1285 | ovl_stack_cpy(dst: ovl_lowerstack(oe), src: stack, n: ctr); |
1286 | } |
1287 | |
1288 | if (upperopaque) |
1289 | ovl_dentry_set_opaque(dentry); |
1290 | if (d.xwhiteouts) |
1291 | ovl_dentry_set_xwhiteouts(dentry); |
1292 | |
1293 | if (upperdentry) |
1294 | ovl_dentry_set_upper_alias(dentry); |
1295 | else if (index) { |
1296 | struct path upperpath = { |
1297 | .dentry = upperdentry = dget(dentry: index), |
1298 | .mnt = ovl_upper_mnt(ofs), |
1299 | }; |
1300 | |
1301 | /* |
1302 | * It's safe to assign upperredirect here: the previous |
1303 | * assignment of happens only if upperdentry is non-NULL, and |
1304 | * this one only if upperdentry is NULL. |
1305 | */ |
1306 | upperredirect = ovl_get_redirect_xattr(ofs, path: &upperpath, padding: 0); |
1307 | if (IS_ERR(ptr: upperredirect)) { |
1308 | err = PTR_ERR(ptr: upperredirect); |
1309 | upperredirect = NULL; |
1310 | goto out_free_oe; |
1311 | } |
1312 | err = ovl_check_metacopy_xattr(ofs, path: &upperpath, NULL); |
1313 | if (err < 0) |
1314 | goto out_free_oe; |
1315 | uppermetacopy = err; |
1316 | metacopy_size = err; |
1317 | } |
1318 | |
1319 | if (upperdentry || ctr) { |
1320 | struct ovl_inode_params oip = { |
1321 | .upperdentry = upperdentry, |
1322 | .oe = oe, |
1323 | .index = index, |
1324 | .redirect = upperredirect, |
1325 | }; |
1326 | |
1327 | /* Store lowerdata redirect for lazy lookup */ |
1328 | if (ctr > 1 && !d.is_dir && !stack[ctr - 1].dentry) { |
1329 | oip.lowerdata_redirect = d.redirect; |
1330 | d.redirect = NULL; |
1331 | } |
1332 | inode = ovl_get_inode(sb: dentry->d_sb, oip: &oip); |
1333 | err = PTR_ERR(ptr: inode); |
1334 | if (IS_ERR(ptr: inode)) |
1335 | goto out_free_oe; |
1336 | if (upperdentry && !uppermetacopy) |
1337 | ovl_set_flag(flag: OVL_UPPERDATA, inode); |
1338 | |
1339 | if (metacopy_size > OVL_METACOPY_MIN_SIZE) |
1340 | ovl_set_flag(flag: OVL_HAS_DIGEST, inode); |
1341 | } |
1342 | |
1343 | ovl_dentry_init_reval(dentry, upperdentry, oe: OVL_I_E(inode)); |
1344 | |
1345 | revert_creds(old_cred); |
1346 | if (origin_path) { |
1347 | dput(origin_path->dentry); |
1348 | kfree(objp: origin_path); |
1349 | } |
1350 | dput(index); |
1351 | ovl_stack_free(stack, n: ctr); |
1352 | kfree(objp: d.redirect); |
1353 | return d_splice_alias(inode, dentry); |
1354 | |
1355 | out_free_oe: |
1356 | ovl_free_entry(oe); |
1357 | out_put: |
1358 | dput(index); |
1359 | ovl_stack_free(stack, n: ctr); |
1360 | out_put_upper: |
1361 | if (origin_path) { |
1362 | dput(origin_path->dentry); |
1363 | kfree(objp: origin_path); |
1364 | } |
1365 | dput(upperdentry); |
1366 | kfree(objp: upperredirect); |
1367 | out: |
1368 | kfree(objp: d.redirect); |
1369 | revert_creds(old_cred); |
1370 | return ERR_PTR(error: err); |
1371 | } |
1372 | |
1373 | bool ovl_lower_positive(struct dentry *dentry) |
1374 | { |
1375 | struct ovl_entry *poe = OVL_E(dentry: dentry->d_parent); |
1376 | const struct qstr *name = &dentry->d_name; |
1377 | const struct cred *old_cred; |
1378 | unsigned int i; |
1379 | bool positive = false; |
1380 | bool done = false; |
1381 | |
1382 | /* |
1383 | * If dentry is negative, then lower is positive iff this is a |
1384 | * whiteout. |
1385 | */ |
1386 | if (!dentry->d_inode) |
1387 | return ovl_dentry_is_opaque(dentry); |
1388 | |
1389 | /* Negative upper -> positive lower */ |
1390 | if (!ovl_dentry_upper(dentry)) |
1391 | return true; |
1392 | |
1393 | old_cred = ovl_override_creds(sb: dentry->d_sb); |
1394 | /* Positive upper -> have to look up lower to see whether it exists */ |
1395 | for (i = 0; !done && !positive && i < ovl_numlower(oe: poe); i++) { |
1396 | struct dentry *this; |
1397 | struct ovl_path *parentpath = &ovl_lowerstack(oe: poe)[i]; |
1398 | |
1399 | this = lookup_one_positive_unlocked( |
1400 | idmap: mnt_idmap(mnt: parentpath->layer->mnt), |
1401 | name: name->name, base: parentpath->dentry, len: name->len); |
1402 | if (IS_ERR(ptr: this)) { |
1403 | switch (PTR_ERR(ptr: this)) { |
1404 | case -ENOENT: |
1405 | case -ENAMETOOLONG: |
1406 | break; |
1407 | |
1408 | default: |
1409 | /* |
1410 | * Assume something is there, we just couldn't |
1411 | * access it. |
1412 | */ |
1413 | positive = true; |
1414 | break; |
1415 | } |
1416 | } else { |
1417 | struct path path = { |
1418 | .dentry = this, |
1419 | .mnt = parentpath->layer->mnt, |
1420 | }; |
1421 | positive = !ovl_path_is_whiteout(ofs: OVL_FS(sb: dentry->d_sb), path: &path); |
1422 | done = true; |
1423 | dput(this); |
1424 | } |
1425 | } |
1426 | revert_creds(old_cred); |
1427 | |
1428 | return positive; |
1429 | } |
1430 | |