1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 *
4 * Copyright (C) 2011 Novell Inc.
5 */
6
7 #include <linux/module.h>
8 #include <linux/fs.h>
9 #include <linux/slab.h>
10 #include <linux/file.h>
11 #include <linux/splice.h>
12 #include <linux/xattr.h>
13 #include <linux/security.h>
14 #include <linux/uaccess.h>
15 #include <linux/sched/signal.h>
16 #include <linux/cred.h>
17 #include <linux/namei.h>
18 #include <linux/fdtable.h>
19 #include <linux/ratelimit.h>
20 #include <linux/exportfs.h>
21 #include "overlayfs.h"
22
23 #define OVL_COPY_UP_CHUNK_SIZE (1 << 20)
24
ovl_ccup_set(const char * buf,const struct kernel_param * param)25 static int ovl_ccup_set(const char *buf, const struct kernel_param *param)
26 {
27 pr_warn("\"check_copy_up\" module option is obsolete\n");
28 return 0;
29 }
30
ovl_ccup_get(char * buf,const struct kernel_param * param)31 static int ovl_ccup_get(char *buf, const struct kernel_param *param)
32 {
33 return sprintf(buf, "N\n");
34 }
35
36 module_param_call(check_copy_up, ovl_ccup_set, ovl_ccup_get, NULL, 0644);
37 MODULE_PARM_DESC(check_copy_up, "Obsolete; does nothing");
38
ovl_must_copy_xattr(const char * name)39 static bool ovl_must_copy_xattr(const char *name)
40 {
41 return !strcmp(name, XATTR_POSIX_ACL_ACCESS) ||
42 !strcmp(name, XATTR_POSIX_ACL_DEFAULT) ||
43 !strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN);
44 }
45
ovl_copy_xattr(struct super_block * sb,struct dentry * old,struct dentry * new)46 int ovl_copy_xattr(struct super_block *sb, struct dentry *old,
47 struct dentry *new)
48 {
49 ssize_t list_size, size, value_size = 0;
50 char *buf, *name, *value = NULL;
51 int error = 0;
52 size_t slen;
53
54 if (!(old->d_inode->i_opflags & IOP_XATTR) ||
55 !(new->d_inode->i_opflags & IOP_XATTR))
56 return 0;
57
58 list_size = vfs_listxattr(old, NULL, 0);
59 if (list_size <= 0) {
60 if (list_size == -EOPNOTSUPP)
61 return 0;
62 return list_size;
63 }
64
65 buf = kzalloc(list_size, GFP_KERNEL);
66 if (!buf)
67 return -ENOMEM;
68
69 list_size = vfs_listxattr(old, buf, list_size);
70 if (list_size <= 0) {
71 error = list_size;
72 goto out;
73 }
74
75 for (name = buf; list_size; name += slen) {
76 slen = strnlen(name, list_size) + 1;
77
78 /* underlying fs providing us with an broken xattr list? */
79 if (WARN_ON(slen > list_size)) {
80 error = -EIO;
81 break;
82 }
83 list_size -= slen;
84
85 if (ovl_is_private_xattr(sb, name))
86 continue;
87
88 error = security_inode_copy_up_xattr(name);
89 if (error < 0 && error != -EOPNOTSUPP)
90 break;
91 if (error == 1) {
92 error = 0;
93 continue; /* Discard */
94 }
95 retry:
96 size = vfs_getxattr(&init_user_ns, old, name, value, value_size);
97 if (size == -ERANGE)
98 size = vfs_getxattr(&init_user_ns, old, name, NULL, 0);
99
100 if (size < 0) {
101 error = size;
102 break;
103 }
104
105 if (size > value_size) {
106 void *new;
107
108 new = krealloc(value, size, GFP_KERNEL);
109 if (!new) {
110 error = -ENOMEM;
111 break;
112 }
113 value = new;
114 value_size = size;
115 goto retry;
116 }
117
118 error = vfs_setxattr(&init_user_ns, new, name, value, size, 0);
119 if (error) {
120 if (error != -EOPNOTSUPP || ovl_must_copy_xattr(name))
121 break;
122
123 /* Ignore failure to copy unknown xattrs */
124 error = 0;
125 }
126 }
127 kfree(value);
128 out:
129 kfree(buf);
130 return error;
131 }
132
ovl_copy_up_data(struct ovl_fs * ofs,struct path * old,struct path * new,loff_t len)133 static int ovl_copy_up_data(struct ovl_fs *ofs, struct path *old,
134 struct path *new, loff_t len)
135 {
136 struct file *old_file;
137 struct file *new_file;
138 loff_t old_pos = 0;
139 loff_t new_pos = 0;
140 loff_t cloned;
141 loff_t data_pos = -1;
142 loff_t hole_len;
143 bool skip_hole = false;
144 int error = 0;
145
146 if (len == 0)
147 return 0;
148
149 old_file = ovl_path_open(old, O_LARGEFILE | O_RDONLY);
150 if (IS_ERR(old_file))
151 return PTR_ERR(old_file);
152
153 new_file = ovl_path_open(new, O_LARGEFILE | O_WRONLY);
154 if (IS_ERR(new_file)) {
155 error = PTR_ERR(new_file);
156 goto out_fput;
157 }
158
159 /* Try to use clone_file_range to clone up within the same fs */
160 cloned = do_clone_file_range(old_file, 0, new_file, 0, len, 0);
161 if (cloned == len)
162 goto out;
163 /* Couldn't clone, so now we try to copy the data */
164
165 /* Check if lower fs supports seek operation */
166 if (old_file->f_mode & FMODE_LSEEK &&
167 old_file->f_op->llseek)
168 skip_hole = true;
169
170 while (len) {
171 size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
172 long bytes;
173
174 if (len < this_len)
175 this_len = len;
176
177 if (signal_pending_state(TASK_KILLABLE, current)) {
178 error = -EINTR;
179 break;
180 }
181
182 /*
183 * Fill zero for hole will cost unnecessary disk space
184 * and meanwhile slow down the copy-up speed, so we do
185 * an optimization for hole during copy-up, it relies
186 * on SEEK_DATA implementation in lower fs so if lower
187 * fs does not support it, copy-up will behave as before.
188 *
189 * Detail logic of hole detection as below:
190 * When we detect next data position is larger than current
191 * position we will skip that hole, otherwise we copy
192 * data in the size of OVL_COPY_UP_CHUNK_SIZE. Actually,
193 * it may not recognize all kind of holes and sometimes
194 * only skips partial of hole area. However, it will be
195 * enough for most of the use cases.
196 */
197
198 if (skip_hole && data_pos < old_pos) {
199 data_pos = vfs_llseek(old_file, old_pos, SEEK_DATA);
200 if (data_pos > old_pos) {
201 hole_len = data_pos - old_pos;
202 len -= hole_len;
203 old_pos = new_pos = data_pos;
204 continue;
205 } else if (data_pos == -ENXIO) {
206 break;
207 } else if (data_pos < 0) {
208 skip_hole = false;
209 }
210 }
211
212 bytes = do_splice_direct(old_file, &old_pos,
213 new_file, &new_pos,
214 this_len, SPLICE_F_MOVE);
215 if (bytes <= 0) {
216 error = bytes;
217 break;
218 }
219 WARN_ON(old_pos != new_pos);
220
221 len -= bytes;
222 }
223 out:
224 if (!error && ovl_should_sync(ofs))
225 error = vfs_fsync(new_file, 0);
226 fput(new_file);
227 out_fput:
228 fput(old_file);
229 return error;
230 }
231
ovl_set_size(struct dentry * upperdentry,struct kstat * stat)232 static int ovl_set_size(struct dentry *upperdentry, struct kstat *stat)
233 {
234 struct iattr attr = {
235 .ia_valid = ATTR_SIZE,
236 .ia_size = stat->size,
237 };
238
239 return notify_change(&init_user_ns, upperdentry, &attr, NULL);
240 }
241
ovl_set_timestamps(struct dentry * upperdentry,struct kstat * stat)242 static int ovl_set_timestamps(struct dentry *upperdentry, struct kstat *stat)
243 {
244 struct iattr attr = {
245 .ia_valid =
246 ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET,
247 .ia_atime = stat->atime,
248 .ia_mtime = stat->mtime,
249 };
250
251 return notify_change(&init_user_ns, upperdentry, &attr, NULL);
252 }
253
ovl_set_attr(struct dentry * upperdentry,struct kstat * stat)254 int ovl_set_attr(struct dentry *upperdentry, struct kstat *stat)
255 {
256 int err = 0;
257
258 if (!S_ISLNK(stat->mode)) {
259 struct iattr attr = {
260 .ia_valid = ATTR_MODE,
261 .ia_mode = stat->mode,
262 };
263 err = notify_change(&init_user_ns, upperdentry, &attr, NULL);
264 }
265 if (!err) {
266 struct iattr attr = {
267 .ia_valid = ATTR_UID | ATTR_GID,
268 .ia_uid = stat->uid,
269 .ia_gid = stat->gid,
270 };
271 err = notify_change(&init_user_ns, upperdentry, &attr, NULL);
272 }
273 if (!err)
274 ovl_set_timestamps(upperdentry, stat);
275
276 return err;
277 }
278
ovl_encode_real_fh(struct ovl_fs * ofs,struct dentry * real,bool is_upper)279 struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct dentry *real,
280 bool is_upper)
281 {
282 struct ovl_fh *fh;
283 int fh_type, dwords;
284 int buflen = MAX_HANDLE_SZ;
285 uuid_t *uuid = &real->d_sb->s_uuid;
286 int err;
287
288 /* Make sure the real fid stays 32bit aligned */
289 BUILD_BUG_ON(OVL_FH_FID_OFFSET % 4);
290 BUILD_BUG_ON(MAX_HANDLE_SZ + OVL_FH_FID_OFFSET > 255);
291
292 fh = kzalloc(buflen + OVL_FH_FID_OFFSET, GFP_KERNEL);
293 if (!fh)
294 return ERR_PTR(-ENOMEM);
295
296 /*
297 * We encode a non-connectable file handle for non-dir, because we
298 * only need to find the lower inode number and we don't want to pay
299 * the price or reconnecting the dentry.
300 */
301 dwords = buflen >> 2;
302 fh_type = exportfs_encode_fh(real, (void *)fh->fb.fid, &dwords, 0);
303 buflen = (dwords << 2);
304
305 err = -EIO;
306 if (WARN_ON(fh_type < 0) ||
307 WARN_ON(buflen > MAX_HANDLE_SZ) ||
308 WARN_ON(fh_type == FILEID_INVALID))
309 goto out_err;
310
311 fh->fb.version = OVL_FH_VERSION;
312 fh->fb.magic = OVL_FH_MAGIC;
313 fh->fb.type = fh_type;
314 fh->fb.flags = OVL_FH_FLAG_CPU_ENDIAN;
315 /*
316 * When we will want to decode an overlay dentry from this handle
317 * and all layers are on the same fs, if we get a disconncted real
318 * dentry when we decode fid, the only way to tell if we should assign
319 * it to upperdentry or to lowerstack is by checking this flag.
320 */
321 if (is_upper)
322 fh->fb.flags |= OVL_FH_FLAG_PATH_UPPER;
323 fh->fb.len = sizeof(fh->fb) + buflen;
324 if (ofs->config.uuid)
325 fh->fb.uuid = *uuid;
326
327 return fh;
328
329 out_err:
330 kfree(fh);
331 return ERR_PTR(err);
332 }
333
ovl_set_origin(struct ovl_fs * ofs,struct dentry * dentry,struct dentry * lower,struct dentry * upper)334 int ovl_set_origin(struct ovl_fs *ofs, struct dentry *dentry,
335 struct dentry *lower, struct dentry *upper)
336 {
337 const struct ovl_fh *fh = NULL;
338 int err;
339
340 /*
341 * When lower layer doesn't support export operations store a 'null' fh,
342 * so we can use the overlay.origin xattr to distignuish between a copy
343 * up and a pure upper inode.
344 */
345 if (ovl_can_decode_fh(lower->d_sb)) {
346 fh = ovl_encode_real_fh(ofs, lower, false);
347 if (IS_ERR(fh))
348 return PTR_ERR(fh);
349 }
350
351 /*
352 * Do not fail when upper doesn't support xattrs.
353 */
354 err = ovl_check_setxattr(dentry, upper, OVL_XATTR_ORIGIN, fh->buf,
355 fh ? fh->fb.len : 0, 0);
356 kfree(fh);
357
358 /* Ignore -EPERM from setting "user.*" on symlink/special */
359 return err == -EPERM ? 0 : err;
360 }
361
362 /* Store file handle of @upper dir in @index dir entry */
ovl_set_upper_fh(struct ovl_fs * ofs,struct dentry * upper,struct dentry * index)363 static int ovl_set_upper_fh(struct ovl_fs *ofs, struct dentry *upper,
364 struct dentry *index)
365 {
366 const struct ovl_fh *fh;
367 int err;
368
369 fh = ovl_encode_real_fh(ofs, upper, true);
370 if (IS_ERR(fh))
371 return PTR_ERR(fh);
372
373 err = ovl_do_setxattr(ofs, index, OVL_XATTR_UPPER, fh->buf, fh->fb.len);
374
375 kfree(fh);
376 return err;
377 }
378
379 /*
380 * Create and install index entry.
381 *
382 * Caller must hold i_mutex on indexdir.
383 */
ovl_create_index(struct dentry * dentry,struct dentry * origin,struct dentry * upper)384 static int ovl_create_index(struct dentry *dentry, struct dentry *origin,
385 struct dentry *upper)
386 {
387 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
388 struct dentry *indexdir = ovl_indexdir(dentry->d_sb);
389 struct inode *dir = d_inode(indexdir);
390 struct dentry *index = NULL;
391 struct dentry *temp = NULL;
392 struct qstr name = { };
393 int err;
394
395 /*
396 * For now this is only used for creating index entry for directories,
397 * because non-dir are copied up directly to index and then hardlinked
398 * to upper dir.
399 *
400 * TODO: implement create index for non-dir, so we can call it when
401 * encoding file handle for non-dir in case index does not exist.
402 */
403 if (WARN_ON(!d_is_dir(dentry)))
404 return -EIO;
405
406 /* Directory not expected to be indexed before copy up */
407 if (WARN_ON(ovl_test_flag(OVL_INDEX, d_inode(dentry))))
408 return -EIO;
409
410 err = ovl_get_index_name(ofs, origin, &name);
411 if (err)
412 return err;
413
414 temp = ovl_create_temp(indexdir, OVL_CATTR(S_IFDIR | 0));
415 err = PTR_ERR(temp);
416 if (IS_ERR(temp))
417 goto free_name;
418
419 err = ovl_set_upper_fh(ofs, upper, temp);
420 if (err)
421 goto out;
422
423 index = lookup_one_len(name.name, indexdir, name.len);
424 if (IS_ERR(index)) {
425 err = PTR_ERR(index);
426 } else {
427 err = ovl_do_rename(dir, temp, dir, index, 0);
428 dput(index);
429 }
430 out:
431 if (err)
432 ovl_cleanup(dir, temp);
433 dput(temp);
434 free_name:
435 kfree(name.name);
436 return err;
437 }
438
439 struct ovl_copy_up_ctx {
440 struct dentry *parent;
441 struct dentry *dentry;
442 struct path lowerpath;
443 struct kstat stat;
444 struct kstat pstat;
445 const char *link;
446 struct dentry *destdir;
447 struct qstr destname;
448 struct dentry *workdir;
449 bool origin;
450 bool indexed;
451 bool metacopy;
452 };
453
ovl_link_up(struct ovl_copy_up_ctx * c)454 static int ovl_link_up(struct ovl_copy_up_ctx *c)
455 {
456 int err;
457 struct dentry *upper;
458 struct dentry *upperdir = ovl_dentry_upper(c->parent);
459 struct inode *udir = d_inode(upperdir);
460
461 /* Mark parent "impure" because it may now contain non-pure upper */
462 err = ovl_set_impure(c->parent, upperdir);
463 if (err)
464 return err;
465
466 err = ovl_set_nlink_lower(c->dentry);
467 if (err)
468 return err;
469
470 inode_lock_nested(udir, I_MUTEX_PARENT);
471 upper = lookup_one_len(c->dentry->d_name.name, upperdir,
472 c->dentry->d_name.len);
473 err = PTR_ERR(upper);
474 if (!IS_ERR(upper)) {
475 err = ovl_do_link(ovl_dentry_upper(c->dentry), udir, upper);
476 dput(upper);
477
478 if (!err) {
479 /* Restore timestamps on parent (best effort) */
480 ovl_set_timestamps(upperdir, &c->pstat);
481 ovl_dentry_set_upper_alias(c->dentry);
482 }
483 }
484 inode_unlock(udir);
485 if (err)
486 return err;
487
488 err = ovl_set_nlink_upper(c->dentry);
489
490 return err;
491 }
492
ovl_copy_up_inode(struct ovl_copy_up_ctx * c,struct dentry * temp)493 static int ovl_copy_up_inode(struct ovl_copy_up_ctx *c, struct dentry *temp)
494 {
495 struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
496 int err;
497
498 /*
499 * Copy up data first and then xattrs. Writing data after
500 * xattrs will remove security.capability xattr automatically.
501 */
502 if (S_ISREG(c->stat.mode) && !c->metacopy) {
503 struct path upperpath, datapath;
504
505 ovl_path_upper(c->dentry, &upperpath);
506 if (WARN_ON(upperpath.dentry != NULL))
507 return -EIO;
508 upperpath.dentry = temp;
509
510 ovl_path_lowerdata(c->dentry, &datapath);
511 err = ovl_copy_up_data(ofs, &datapath, &upperpath,
512 c->stat.size);
513 if (err)
514 return err;
515 }
516
517 err = ovl_copy_xattr(c->dentry->d_sb, c->lowerpath.dentry, temp);
518 if (err)
519 return err;
520
521 /*
522 * Store identifier of lower inode in upper inode xattr to
523 * allow lookup of the copy up origin inode.
524 *
525 * Don't set origin when we are breaking the association with a lower
526 * hard link.
527 */
528 if (c->origin) {
529 err = ovl_set_origin(ofs, c->dentry, c->lowerpath.dentry, temp);
530 if (err)
531 return err;
532 }
533
534 if (c->metacopy) {
535 err = ovl_check_setxattr(c->dentry, temp, OVL_XATTR_METACOPY,
536 NULL, 0, -EOPNOTSUPP);
537 if (err)
538 return err;
539 }
540
541 inode_lock(temp->d_inode);
542 if (S_ISREG(c->stat.mode))
543 err = ovl_set_size(temp, &c->stat);
544 if (!err)
545 err = ovl_set_attr(temp, &c->stat);
546 inode_unlock(temp->d_inode);
547
548 return err;
549 }
550
551 struct ovl_cu_creds {
552 const struct cred *old;
553 struct cred *new;
554 };
555
ovl_prep_cu_creds(struct dentry * dentry,struct ovl_cu_creds * cc)556 static int ovl_prep_cu_creds(struct dentry *dentry, struct ovl_cu_creds *cc)
557 {
558 int err;
559
560 cc->old = cc->new = NULL;
561 err = security_inode_copy_up(dentry, &cc->new);
562 if (err < 0)
563 return err;
564
565 if (cc->new)
566 cc->old = override_creds(cc->new);
567
568 return 0;
569 }
570
ovl_revert_cu_creds(struct ovl_cu_creds * cc)571 static void ovl_revert_cu_creds(struct ovl_cu_creds *cc)
572 {
573 if (cc->new) {
574 revert_creds(cc->old);
575 put_cred(cc->new);
576 }
577 }
578
579 /*
580 * Copyup using workdir to prepare temp file. Used when copying up directories,
581 * special files or when upper fs doesn't support O_TMPFILE.
582 */
ovl_copy_up_workdir(struct ovl_copy_up_ctx * c)583 static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
584 {
585 struct inode *inode;
586 struct inode *udir = d_inode(c->destdir), *wdir = d_inode(c->workdir);
587 struct dentry *temp, *upper;
588 struct ovl_cu_creds cc;
589 int err;
590 struct ovl_cattr cattr = {
591 /* Can't properly set mode on creation because of the umask */
592 .mode = c->stat.mode & S_IFMT,
593 .rdev = c->stat.rdev,
594 .link = c->link
595 };
596
597 /* workdir and destdir could be the same when copying up to indexdir */
598 err = -EIO;
599 if (lock_rename(c->workdir, c->destdir) != NULL)
600 goto unlock;
601
602 err = ovl_prep_cu_creds(c->dentry, &cc);
603 if (err)
604 goto unlock;
605
606 temp = ovl_create_temp(c->workdir, &cattr);
607 ovl_revert_cu_creds(&cc);
608
609 err = PTR_ERR(temp);
610 if (IS_ERR(temp))
611 goto unlock;
612
613 err = ovl_copy_up_inode(c, temp);
614 if (err)
615 goto cleanup;
616
617 if (S_ISDIR(c->stat.mode) && c->indexed) {
618 err = ovl_create_index(c->dentry, c->lowerpath.dentry, temp);
619 if (err)
620 goto cleanup;
621 }
622
623 upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
624 err = PTR_ERR(upper);
625 if (IS_ERR(upper))
626 goto cleanup;
627
628 err = ovl_do_rename(wdir, temp, udir, upper, 0);
629 dput(upper);
630 if (err)
631 goto cleanup;
632
633 if (!c->metacopy)
634 ovl_set_upperdata(d_inode(c->dentry));
635 inode = d_inode(c->dentry);
636 ovl_inode_update(inode, temp);
637 if (S_ISDIR(inode->i_mode))
638 ovl_set_flag(OVL_WHITEOUTS, inode);
639 unlock:
640 unlock_rename(c->workdir, c->destdir);
641
642 return err;
643
644 cleanup:
645 ovl_cleanup(wdir, temp);
646 dput(temp);
647 goto unlock;
648 }
649
650 /* Copyup using O_TMPFILE which does not require cross dir locking */
ovl_copy_up_tmpfile(struct ovl_copy_up_ctx * c)651 static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
652 {
653 struct inode *udir = d_inode(c->destdir);
654 struct dentry *temp, *upper;
655 struct ovl_cu_creds cc;
656 int err;
657
658 err = ovl_prep_cu_creds(c->dentry, &cc);
659 if (err)
660 return err;
661
662 temp = ovl_do_tmpfile(c->workdir, c->stat.mode);
663 ovl_revert_cu_creds(&cc);
664
665 if (IS_ERR(temp))
666 return PTR_ERR(temp);
667
668 err = ovl_copy_up_inode(c, temp);
669 if (err)
670 goto out_dput;
671
672 inode_lock_nested(udir, I_MUTEX_PARENT);
673
674 upper = lookup_one_len(c->destname.name, c->destdir, c->destname.len);
675 err = PTR_ERR(upper);
676 if (!IS_ERR(upper)) {
677 err = ovl_do_link(temp, udir, upper);
678 dput(upper);
679 }
680 inode_unlock(udir);
681
682 if (err)
683 goto out_dput;
684
685 if (!c->metacopy)
686 ovl_set_upperdata(d_inode(c->dentry));
687 ovl_inode_update(d_inode(c->dentry), temp);
688
689 return 0;
690
691 out_dput:
692 dput(temp);
693 return err;
694 }
695
696 /*
697 * Copy up a single dentry
698 *
699 * All renames start with copy up of source if necessary. The actual
700 * rename will only proceed once the copy up was successful. Copy up uses
701 * upper parent i_mutex for exclusion. Since rename can change d_parent it
702 * is possible that the copy up will lock the old parent. At that point
703 * the file will have already been copied up anyway.
704 */
ovl_do_copy_up(struct ovl_copy_up_ctx * c)705 static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
706 {
707 int err;
708 struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
709 bool to_index = false;
710
711 /*
712 * Indexed non-dir is copied up directly to the index entry and then
713 * hardlinked to upper dir. Indexed dir is copied up to indexdir,
714 * then index entry is created and then copied up dir installed.
715 * Copying dir up to indexdir instead of workdir simplifies locking.
716 */
717 if (ovl_need_index(c->dentry)) {
718 c->indexed = true;
719 if (S_ISDIR(c->stat.mode))
720 c->workdir = ovl_indexdir(c->dentry->d_sb);
721 else
722 to_index = true;
723 }
724
725 if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || to_index)
726 c->origin = true;
727
728 if (to_index) {
729 c->destdir = ovl_indexdir(c->dentry->d_sb);
730 err = ovl_get_index_name(ofs, c->lowerpath.dentry, &c->destname);
731 if (err)
732 return err;
733 } else if (WARN_ON(!c->parent)) {
734 /* Disconnected dentry must be copied up to index dir */
735 return -EIO;
736 } else {
737 /*
738 * Mark parent "impure" because it may now contain non-pure
739 * upper
740 */
741 err = ovl_set_impure(c->parent, c->destdir);
742 if (err)
743 return err;
744 }
745
746 /* Should we copyup with O_TMPFILE or with workdir? */
747 if (S_ISREG(c->stat.mode) && ofs->tmpfile)
748 err = ovl_copy_up_tmpfile(c);
749 else
750 err = ovl_copy_up_workdir(c);
751 if (err)
752 goto out;
753
754 if (c->indexed)
755 ovl_set_flag(OVL_INDEX, d_inode(c->dentry));
756
757 if (to_index) {
758 /* Initialize nlink for copy up of disconnected dentry */
759 err = ovl_set_nlink_upper(c->dentry);
760 } else {
761 struct inode *udir = d_inode(c->destdir);
762
763 /* Restore timestamps on parent (best effort) */
764 inode_lock(udir);
765 ovl_set_timestamps(c->destdir, &c->pstat);
766 inode_unlock(udir);
767
768 ovl_dentry_set_upper_alias(c->dentry);
769 }
770
771 out:
772 if (to_index)
773 kfree(c->destname.name);
774 return err;
775 }
776
ovl_need_meta_copy_up(struct dentry * dentry,umode_t mode,int flags)777 static bool ovl_need_meta_copy_up(struct dentry *dentry, umode_t mode,
778 int flags)
779 {
780 struct ovl_fs *ofs = dentry->d_sb->s_fs_info;
781
782 if (!ofs->config.metacopy)
783 return false;
784
785 if (!S_ISREG(mode))
786 return false;
787
788 if (flags && ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC)))
789 return false;
790
791 return true;
792 }
793
ovl_getxattr(struct dentry * dentry,char * name,char ** value)794 static ssize_t ovl_getxattr(struct dentry *dentry, char *name, char **value)
795 {
796 ssize_t res;
797 char *buf;
798
799 res = vfs_getxattr(&init_user_ns, dentry, name, NULL, 0);
800 if (res == -ENODATA || res == -EOPNOTSUPP)
801 res = 0;
802
803 if (res > 0) {
804 buf = kzalloc(res, GFP_KERNEL);
805 if (!buf)
806 return -ENOMEM;
807
808 res = vfs_getxattr(&init_user_ns, dentry, name, buf, res);
809 if (res < 0)
810 kfree(buf);
811 else
812 *value = buf;
813 }
814 return res;
815 }
816
817 /* Copy up data of an inode which was copied up metadata only in the past. */
ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx * c)818 static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
819 {
820 struct ovl_fs *ofs = OVL_FS(c->dentry->d_sb);
821 struct path upperpath, datapath;
822 int err;
823 char *capability = NULL;
824 ssize_t cap_size;
825
826 ovl_path_upper(c->dentry, &upperpath);
827 if (WARN_ON(upperpath.dentry == NULL))
828 return -EIO;
829
830 ovl_path_lowerdata(c->dentry, &datapath);
831 if (WARN_ON(datapath.dentry == NULL))
832 return -EIO;
833
834 if (c->stat.size) {
835 err = cap_size = ovl_getxattr(upperpath.dentry, XATTR_NAME_CAPS,
836 &capability);
837 if (cap_size < 0)
838 goto out;
839 }
840
841 err = ovl_copy_up_data(ofs, &datapath, &upperpath, c->stat.size);
842 if (err)
843 goto out_free;
844
845 /*
846 * Writing to upper file will clear security.capability xattr. We
847 * don't want that to happen for normal copy-up operation.
848 */
849 if (capability) {
850 err = vfs_setxattr(&init_user_ns, upperpath.dentry,
851 XATTR_NAME_CAPS, capability, cap_size, 0);
852 if (err)
853 goto out_free;
854 }
855
856
857 err = ovl_do_removexattr(ofs, upperpath.dentry, OVL_XATTR_METACOPY);
858 if (err)
859 goto out_free;
860
861 ovl_set_upperdata(d_inode(c->dentry));
862 out_free:
863 kfree(capability);
864 out:
865 return err;
866 }
867
ovl_copy_up_one(struct dentry * parent,struct dentry * dentry,int flags)868 static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
869 int flags)
870 {
871 int err;
872 DEFINE_DELAYED_CALL(done);
873 struct path parentpath;
874 struct ovl_copy_up_ctx ctx = {
875 .parent = parent,
876 .dentry = dentry,
877 .workdir = ovl_workdir(dentry),
878 };
879
880 if (WARN_ON(!ctx.workdir))
881 return -EROFS;
882
883 ovl_path_lower(dentry, &ctx.lowerpath);
884 err = vfs_getattr(&ctx.lowerpath, &ctx.stat,
885 STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
886 if (err)
887 return err;
888
889 ctx.metacopy = ovl_need_meta_copy_up(dentry, ctx.stat.mode, flags);
890
891 if (parent) {
892 ovl_path_upper(parent, &parentpath);
893 ctx.destdir = parentpath.dentry;
894 ctx.destname = dentry->d_name;
895
896 err = vfs_getattr(&parentpath, &ctx.pstat,
897 STATX_ATIME | STATX_MTIME,
898 AT_STATX_SYNC_AS_STAT);
899 if (err)
900 return err;
901 }
902
903 /* maybe truncate regular file. this has no effect on dirs */
904 if (flags & O_TRUNC)
905 ctx.stat.size = 0;
906
907 if (S_ISLNK(ctx.stat.mode)) {
908 ctx.link = vfs_get_link(ctx.lowerpath.dentry, &done);
909 if (IS_ERR(ctx.link))
910 return PTR_ERR(ctx.link);
911 }
912
913 err = ovl_copy_up_start(dentry, flags);
914 /* err < 0: interrupted, err > 0: raced with another copy-up */
915 if (unlikely(err)) {
916 if (err > 0)
917 err = 0;
918 } else {
919 if (!ovl_dentry_upper(dentry))
920 err = ovl_do_copy_up(&ctx);
921 if (!err && parent && !ovl_dentry_has_upper_alias(dentry))
922 err = ovl_link_up(&ctx);
923 if (!err && ovl_dentry_needs_data_copy_up_locked(dentry, flags))
924 err = ovl_copy_up_meta_inode_data(&ctx);
925 ovl_copy_up_end(dentry);
926 }
927 do_delayed_call(&done);
928
929 return err;
930 }
931
ovl_copy_up_flags(struct dentry * dentry,int flags)932 static int ovl_copy_up_flags(struct dentry *dentry, int flags)
933 {
934 int err = 0;
935 const struct cred *old_cred;
936 bool disconnected = (dentry->d_flags & DCACHE_DISCONNECTED);
937
938 /*
939 * With NFS export, copy up can get called for a disconnected non-dir.
940 * In this case, we will copy up lower inode to index dir without
941 * linking it to upper dir.
942 */
943 if (WARN_ON(disconnected && d_is_dir(dentry)))
944 return -EIO;
945
946 old_cred = ovl_override_creds(dentry->d_sb);
947 while (!err) {
948 struct dentry *next;
949 struct dentry *parent = NULL;
950
951 if (ovl_already_copied_up(dentry, flags))
952 break;
953
954 next = dget(dentry);
955 /* find the topmost dentry not yet copied up */
956 for (; !disconnected;) {
957 parent = dget_parent(next);
958
959 if (ovl_dentry_upper(parent))
960 break;
961
962 dput(next);
963 next = parent;
964 }
965
966 err = ovl_copy_up_one(parent, next, flags);
967
968 dput(parent);
969 dput(next);
970 }
971 revert_creds(old_cred);
972
973 return err;
974 }
975
ovl_open_need_copy_up(struct dentry * dentry,int flags)976 static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
977 {
978 /* Copy up of disconnected dentry does not set upper alias */
979 if (ovl_already_copied_up(dentry, flags))
980 return false;
981
982 if (special_file(d_inode(dentry)->i_mode))
983 return false;
984
985 if (!ovl_open_flags_need_copy_up(flags))
986 return false;
987
988 return true;
989 }
990
ovl_maybe_copy_up(struct dentry * dentry,int flags)991 int ovl_maybe_copy_up(struct dentry *dentry, int flags)
992 {
993 int err = 0;
994
995 if (ovl_open_need_copy_up(dentry, flags)) {
996 err = ovl_want_write(dentry);
997 if (!err) {
998 err = ovl_copy_up_flags(dentry, flags);
999 ovl_drop_write(dentry);
1000 }
1001 }
1002
1003 return err;
1004 }
1005
ovl_copy_up_with_data(struct dentry * dentry)1006 int ovl_copy_up_with_data(struct dentry *dentry)
1007 {
1008 return ovl_copy_up_flags(dentry, O_WRONLY);
1009 }
1010
ovl_copy_up(struct dentry * dentry)1011 int ovl_copy_up(struct dentry *dentry)
1012 {
1013 return ovl_copy_up_flags(dentry, 0);
1014 }
1015