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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *
4 * Copyright (C) 2011 Novell Inc.
5 */
6
7#include <linux/fs.h>
8#include <linux/slab.h>
9#include <linux/cred.h>
10#include <linux/xattr.h>
11#include <linux/ratelimit.h>
12#include <linux/fiemap.h>
13#include <linux/fileattr.h>
14#include <linux/security.h>
15#include <linux/namei.h>
16#include <linux/posix_acl.h>
17#include <linux/posix_acl_xattr.h>
18#include "overlayfs.h"
19
20
21int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
22 struct iattr *attr)
23{
24 int err;
25 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
26 bool full_copy_up = false;
27 struct dentry *upperdentry;
28 const struct cred *old_cred;
29
30 err = setattr_prepare(&nop_mnt_idmap, dentry, attr);
31 if (err)
32 return err;
33
34 if (attr->ia_valid & ATTR_SIZE) {
35 /* Truncate should trigger data copy up as well */
36 full_copy_up = true;
37 }
38
39 if (!full_copy_up)
40 err = ovl_copy_up(dentry);
41 else
42 err = ovl_copy_up_with_data(dentry);
43 if (!err) {
44 struct inode *winode = NULL;
45
46 upperdentry = ovl_dentry_upper(dentry);
47
48 if (attr->ia_valid & ATTR_SIZE) {
49 winode = d_inode(upperdentry);
50 err = get_write_access(winode);
51 if (err)
52 goto out;
53 }
54
55 if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
56 attr->ia_valid &= ~ATTR_MODE;
57
58 /*
59 * We might have to translate ovl file into real file object
60 * once use cases emerge. For now, simply don't let underlying
61 * filesystem rely on attr->ia_file
62 */
63 attr->ia_valid &= ~ATTR_FILE;
64
65 /*
66 * If open(O_TRUNC) is done, VFS calls ->setattr with ATTR_OPEN
67 * set. Overlayfs does not pass O_TRUNC flag to underlying
68 * filesystem during open -> do not pass ATTR_OPEN. This
69 * disables optimization in fuse which assumes open(O_TRUNC)
70 * already set file size to 0. But we never passed O_TRUNC to
71 * fuse. So by clearing ATTR_OPEN, fuse will be forced to send
72 * setattr request to server.
73 */
74 attr->ia_valid &= ~ATTR_OPEN;
75
76 err = ovl_want_write(dentry);
77 if (err)
78 goto out_put_write;
79
80 inode_lock(upperdentry->d_inode);
81 old_cred = ovl_override_creds(dentry->d_sb);
82 err = ovl_do_notify_change(ofs, upperdentry, attr);
83 ovl_revert_creds(old_cred);
84 if (!err)
85 ovl_copyattr(dentry->d_inode);
86 inode_unlock(upperdentry->d_inode);
87 ovl_drop_write(dentry);
88
89out_put_write:
90 if (winode)
91 put_write_access(winode);
92 }
93out:
94 return err;
95}
96
97static void ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid)
98{
99 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
100 bool samefs = ovl_same_fs(ofs);
101 unsigned int xinobits = ovl_xino_bits(ofs);
102 unsigned int xinoshift = 64 - xinobits;
103
104 if (samefs) {
105 /*
106 * When all layers are on the same fs, all real inode
107 * number are unique, so we use the overlay st_dev,
108 * which is friendly to du -x.
109 */
110 stat->dev = dentry->d_sb->s_dev;
111 return;
112 } else if (xinobits) {
113 /*
114 * All inode numbers of underlying fs should not be using the
115 * high xinobits, so we use high xinobits to partition the
116 * overlay st_ino address space. The high bits holds the fsid
117 * (upper fsid is 0). The lowest xinobit is reserved for mapping
118 * the non-persistent inode numbers range in case of overflow.
119 * This way all overlay inode numbers are unique and use the
120 * overlay st_dev.
121 */
122 if (likely(!(stat->ino >> xinoshift))) {
123 stat->ino |= ((u64)fsid) << (xinoshift + 1);
124 stat->dev = dentry->d_sb->s_dev;
125 return;
126 } else if (ovl_xino_warn(ofs)) {
127 pr_warn_ratelimited("inode number too big (%pd2, ino=%llu, xinobits=%d)\n",
128 dentry, stat->ino, xinobits);
129 }
130 }
131
132 /* The inode could not be mapped to a unified st_ino address space */
133 if (S_ISDIR(dentry->d_inode->i_mode)) {
134 /*
135 * Always use the overlay st_dev for directories, so 'find
136 * -xdev' will scan the entire overlay mount and won't cross the
137 * overlay mount boundaries.
138 *
139 * If not all layers are on the same fs the pair {real st_ino;
140 * overlay st_dev} is not unique, so use the non persistent
141 * overlay st_ino for directories.
142 */
143 stat->dev = dentry->d_sb->s_dev;
144 stat->ino = dentry->d_inode->i_ino;
145 } else {
146 /*
147 * For non-samefs setup, if we cannot map all layers st_ino
148 * to a unified address space, we need to make sure that st_dev
149 * is unique per underlying fs, so we use the unique anonymous
150 * bdev assigned to the underlying fs.
151 */
152 stat->dev = ofs->fs[fsid].pseudo_dev;
153 }
154}
155
156int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
157 struct kstat *stat, u32 request_mask, unsigned int flags)
158{
159 struct dentry *dentry = path->dentry;
160 enum ovl_path_type type;
161 struct path realpath;
162 const struct cred *old_cred;
163 struct inode *inode = d_inode(dentry);
164 bool is_dir = S_ISDIR(inode->i_mode);
165 int fsid = 0;
166 int err;
167 bool metacopy_blocks = false;
168
169 metacopy_blocks = ovl_is_metacopy_dentry(dentry);
170
171 type = ovl_path_real(dentry, &realpath);
172 old_cred = ovl_override_creds(dentry->d_sb);
173 err = vfs_getattr_nosec(&realpath, stat, request_mask, flags);
174 if (err)
175 goto out;
176
177 /* Report the effective immutable/append-only STATX flags */
178 generic_fill_statx_attr(inode, stat);
179
180 /*
181 * For non-dir or same fs, we use st_ino of the copy up origin.
182 * This guaranties constant st_dev/st_ino across copy up.
183 * With xino feature and non-samefs, we use st_ino of the copy up
184 * origin masked with high bits that represent the layer id.
185 *
186 * If lower filesystem supports NFS file handles, this also guaranties
187 * persistent st_ino across mount cycle.
188 */
189 if (!is_dir || ovl_same_dev(OVL_FS(dentry->d_sb))) {
190 if (!OVL_TYPE_UPPER(type)) {
191 fsid = ovl_layer_lower(dentry)->fsid;
192 } else if (OVL_TYPE_ORIGIN(type)) {
193 struct kstat lowerstat;
194 u32 lowermask = STATX_INO | STATX_BLOCKS |
195 (!is_dir ? STATX_NLINK : 0);
196
197 ovl_path_lower(dentry, &realpath);
198 err = vfs_getattr_nosec(&realpath, &lowerstat, lowermask,
199 flags);
200 if (err)
201 goto out;
202
203 /*
204 * Lower hardlinks may be broken on copy up to different
205 * upper files, so we cannot use the lower origin st_ino
206 * for those different files, even for the same fs case.
207 *
208 * Similarly, several redirected dirs can point to the
209 * same dir on a lower layer. With the "verify_lower"
210 * feature, we do not use the lower origin st_ino, if
211 * we haven't verified that this redirect is unique.
212 *
213 * With inodes index enabled, it is safe to use st_ino
214 * of an indexed origin. The index validates that the
215 * upper hardlink is not broken and that a redirected
216 * dir is the only redirect to that origin.
217 */
218 if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
219 (!ovl_verify_lower(dentry->d_sb) &&
220 (is_dir || lowerstat.nlink == 1))) {
221 fsid = ovl_layer_lower(dentry)->fsid;
222 stat->ino = lowerstat.ino;
223 }
224
225 /*
226 * If we are querying a metacopy dentry and lower
227 * dentry is data dentry, then use the blocks we
228 * queried just now. We don't have to do additional
229 * vfs_getattr(). If lower itself is metacopy, then
230 * additional vfs_getattr() is unavoidable.
231 */
232 if (metacopy_blocks &&
233 realpath.dentry == ovl_dentry_lowerdata(dentry)) {
234 stat->blocks = lowerstat.blocks;
235 metacopy_blocks = false;
236 }
237 }
238
239 if (metacopy_blocks) {
240 /*
241 * If lower is not same as lowerdata or if there was
242 * no origin on upper, we can end up here.
243 * With lazy lowerdata lookup, guess lowerdata blocks
244 * from size to avoid lowerdata lookup on stat(2).
245 */
246 struct kstat lowerdatastat;
247 u32 lowermask = STATX_BLOCKS;
248
249 ovl_path_lowerdata(dentry, &realpath);
250 if (realpath.dentry) {
251 err = vfs_getattr_nosec(&realpath, &lowerdatastat,
252 lowermask, flags);
253 if (err)
254 goto out;
255 } else {
256 lowerdatastat.blocks =
257 round_up(stat->size, stat->blksize) >> 9;
258 }
259 stat->blocks = lowerdatastat.blocks;
260 }
261 }
262
263 ovl_map_dev_ino(dentry, stat, fsid);
264
265 /*
266 * It's probably not worth it to count subdirs to get the
267 * correct link count. nlink=1 seems to pacify 'find' and
268 * other utilities.
269 */
270 if (is_dir && OVL_TYPE_MERGE(type))
271 stat->nlink = 1;
272
273 /*
274 * Return the overlay inode nlinks for indexed upper inodes.
275 * Overlay inode nlink counts the union of the upper hardlinks
276 * and non-covered lower hardlinks. It does not include the upper
277 * index hardlink.
278 */
279 if (!is_dir && ovl_test_flag(OVL_INDEX, d_inode(dentry)))
280 stat->nlink = dentry->d_inode->i_nlink;
281
282out:
283 ovl_revert_creds(old_cred);
284
285 return err;
286}
287
288int ovl_permission(struct mnt_idmap *idmap,
289 struct inode *inode, int mask)
290{
291 struct inode *upperinode = ovl_inode_upper(inode);
292 struct inode *realinode;
293 struct path realpath;
294 const struct cred *old_cred;
295 int err;
296
297 /* Careful in RCU walk mode */
298 realinode = ovl_i_path_real(inode, &realpath);
299 if (!realinode) {
300 WARN_ON(!(mask & MAY_NOT_BLOCK));
301 return -ECHILD;
302 }
303
304 /*
305 * Check overlay inode with the creds of task and underlying inode
306 * with creds of mounter
307 */
308 err = generic_permission(&nop_mnt_idmap, inode, mask);
309 if (err)
310 return err;
311
312 old_cred = ovl_override_creds(inode->i_sb);
313 if (!upperinode &&
314 !special_file(realinode->i_mode) && mask & MAY_WRITE) {
315 mask &= ~(MAY_WRITE | MAY_APPEND);
316 /* Make sure mounter can read file for copy up later */
317 mask |= MAY_READ;
318 }
319 err = inode_permission(mnt_idmap(realpath.mnt), realinode, mask);
320 ovl_revert_creds(old_cred);
321
322 return err;
323}
324
325static const char *ovl_get_link(struct dentry *dentry,
326 struct inode *inode,
327 struct delayed_call *done)
328{
329 const struct cred *old_cred;
330 const char *p;
331
332 if (!dentry)
333 return ERR_PTR(-ECHILD);
334
335 old_cred = ovl_override_creds(dentry->d_sb);
336 p = vfs_get_link(ovl_dentry_real(dentry), done);
337 ovl_revert_creds(old_cred);
338 return p;
339}
340
341#ifdef CONFIG_FS_POSIX_ACL
342/*
343 * Apply the idmapping of the layer to POSIX ACLs. The caller must pass a clone
344 * of the POSIX ACLs retrieved from the lower layer to this function to not
345 * alter the POSIX ACLs for the underlying filesystem.
346 */
347static void ovl_idmap_posix_acl(const struct inode *realinode,
348 struct mnt_idmap *idmap,
349 struct posix_acl *acl)
350{
351 struct user_namespace *fs_userns = i_user_ns(realinode);
352
353 for (unsigned int i = 0; i < acl->a_count; i++) {
354 vfsuid_t vfsuid;
355 vfsgid_t vfsgid;
356
357 struct posix_acl_entry *e = &acl->a_entries[i];
358 switch (e->e_tag) {
359 case ACL_USER:
360 vfsuid = make_vfsuid(idmap, fs_userns, e->e_uid);
361 e->e_uid = vfsuid_into_kuid(vfsuid);
362 break;
363 case ACL_GROUP:
364 vfsgid = make_vfsgid(idmap, fs_userns, e->e_gid);
365 e->e_gid = vfsgid_into_kgid(vfsgid);
366 break;
367 }
368 }
369}
370
371/*
372 * The @noperm argument is used to skip permission checking and is a temporary
373 * measure. Quoting Miklos from an earlier discussion:
374 *
375 * > So there are two paths to getting an acl:
376 * > 1) permission checking and 2) retrieving the value via getxattr(2).
377 * > This is a similar situation as reading a symlink vs. following it.
378 * > When following a symlink overlayfs always reads the link on the
379 * > underlying fs just as if it was a readlink(2) call, calling
380 * > security_inode_readlink() instead of security_inode_follow_link().
381 * > This is logical: we are reading the link from the underlying storage,
382 * > and following it on overlayfs.
383 * >
384 * > Applying the same logic to acl: we do need to call the
385 * > security_inode_getxattr() on the underlying fs, even if just want to
386 * > check permissions on overlay. This is currently not done, which is an
387 * > inconsistency.
388 * >
389 * > Maybe adding the check to ovl_get_acl() is the right way to go, but
390 * > I'm a little afraid of a performance regression. Will look into that.
391 *
392 * Until we have made a decision allow this helper to take the @noperm
393 * argument. We should hopefully be able to remove it soon.
394 */
395struct posix_acl *ovl_get_acl_path(const struct path *path,
396 const char *acl_name, bool noperm)
397{
398 struct posix_acl *real_acl, *clone;
399 struct mnt_idmap *idmap;
400 struct inode *realinode = d_inode(path->dentry);
401
402 idmap = mnt_idmap(path->mnt);
403
404 if (noperm)
405 real_acl = get_inode_acl(realinode, posix_acl_type(acl_name));
406 else
407 real_acl = vfs_get_acl(idmap, path->dentry, acl_name);
408 if (IS_ERR_OR_NULL(real_acl))
409 return real_acl;
410
411 if (!is_idmapped_mnt(path->mnt))
412 return real_acl;
413
414 /*
415 * We cannot alter the ACLs returned from the relevant layer as that
416 * would alter the cached values filesystem wide for the lower
417 * filesystem. Instead we can clone the ACLs and then apply the
418 * relevant idmapping of the layer.
419 */
420 clone = posix_acl_clone(real_acl, GFP_KERNEL);
421 posix_acl_release(real_acl); /* release original acl */
422 if (!clone)
423 return ERR_PTR(-ENOMEM);
424
425 ovl_idmap_posix_acl(realinode, idmap, clone);
426 return clone;
427}
428
429/*
430 * When the relevant layer is an idmapped mount we need to take the idmapping
431 * of the layer into account and translate any ACL_{GROUP,USER} values
432 * according to the idmapped mount.
433 *
434 * We cannot alter the ACLs returned from the relevant layer as that would
435 * alter the cached values filesystem wide for the lower filesystem. Instead we
436 * can clone the ACLs and then apply the relevant idmapping of the layer.
437 *
438 * This is obviously only relevant when idmapped layers are used.
439 */
440struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idmap,
441 struct inode *inode, int type,
442 bool rcu, bool noperm)
443{
444 struct inode *realinode;
445 struct posix_acl *acl;
446 struct path realpath;
447
448 /* Careful in RCU walk mode */
449 realinode = ovl_i_path_real(inode, &realpath);
450 if (!realinode) {
451 WARN_ON(!rcu);
452 return ERR_PTR(-ECHILD);
453 }
454
455 if (!IS_POSIXACL(realinode))
456 return NULL;
457
458 if (rcu) {
459 /*
460 * If the layer is idmapped drop out of RCU path walk
461 * so we can clone the ACLs.
462 */
463 if (is_idmapped_mnt(realpath.mnt))
464 return ERR_PTR(-ECHILD);
465
466 acl = get_cached_acl_rcu(realinode, type);
467 } else {
468 const struct cred *old_cred;
469
470 old_cred = ovl_override_creds(inode->i_sb);
471 acl = ovl_get_acl_path(&realpath, posix_acl_xattr_name(type), noperm);
472 ovl_revert_creds(old_cred);
473 }
474
475 return acl;
476}
477
478static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode,
479 struct posix_acl *acl, int type)
480{
481 int err;
482 struct path realpath;
483 const char *acl_name;
484 const struct cred *old_cred;
485 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
486 struct dentry *upperdentry = ovl_dentry_upper(dentry);
487 struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
488
489 /*
490 * If ACL is to be removed from a lower file, check if it exists in
491 * the first place before copying it up.
492 */
493 acl_name = posix_acl_xattr_name(type);
494 if (!acl && !upperdentry) {
495 struct posix_acl *real_acl;
496
497 ovl_path_lower(dentry, &realpath);
498 old_cred = ovl_override_creds(dentry->d_sb);
499 real_acl = vfs_get_acl(mnt_idmap(realpath.mnt), realdentry,
500 acl_name);
501 ovl_revert_creds(old_cred);
502 if (IS_ERR(real_acl)) {
503 err = PTR_ERR(real_acl);
504 goto out;
505 }
506 posix_acl_release(real_acl);
507 }
508
509 if (!upperdentry) {
510 err = ovl_copy_up(dentry);
511 if (err)
512 goto out;
513
514 realdentry = ovl_dentry_upper(dentry);
515 }
516
517 err = ovl_want_write(dentry);
518 if (err)
519 goto out;
520
521 old_cred = ovl_override_creds(dentry->d_sb);
522 if (acl)
523 err = ovl_do_set_acl(ofs, realdentry, acl_name, acl);
524 else
525 err = ovl_do_remove_acl(ofs, realdentry, acl_name);
526 ovl_revert_creds(old_cred);
527 ovl_drop_write(dentry);
528
529 /* copy c/mtime */
530 ovl_copyattr(inode);
531out:
532 return err;
533}
534
535int ovl_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
536 struct posix_acl *acl, int type)
537{
538 int err;
539 struct inode *inode = d_inode(dentry);
540 struct dentry *workdir = ovl_workdir(dentry);
541 struct inode *realinode = ovl_inode_real(inode);
542
543 if (!IS_POSIXACL(d_inode(workdir)))
544 return -EOPNOTSUPP;
545 if (!realinode->i_op->set_acl)
546 return -EOPNOTSUPP;
547 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
548 return acl ? -EACCES : 0;
549 if (!inode_owner_or_capable(&nop_mnt_idmap, inode))
550 return -EPERM;
551
552 /*
553 * Check if sgid bit needs to be cleared (actual setacl operation will
554 * be done with mounter's capabilities and so that won't do it for us).
555 */
556 if (unlikely(inode->i_mode & S_ISGID) && type == ACL_TYPE_ACCESS &&
557 !in_group_p(inode->i_gid) &&
558 !capable_wrt_inode_uidgid(&nop_mnt_idmap, inode, CAP_FSETID)) {
559 struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
560
561 err = ovl_setattr(&nop_mnt_idmap, dentry, &iattr);
562 if (err)
563 return err;
564 }
565
566 return ovl_set_or_remove_acl(dentry, inode, acl, type);
567}
568#endif
569
570int ovl_update_time(struct inode *inode, int flags)
571{
572 if (flags & S_ATIME) {
573 struct ovl_fs *ofs = OVL_FS(inode->i_sb);
574 struct path upperpath = {
575 .mnt = ovl_upper_mnt(ofs),
576 .dentry = ovl_upperdentry_dereference(OVL_I(inode)),
577 };
578
579 if (upperpath.dentry) {
580 touch_atime(&upperpath);
581 inode_set_atime_to_ts(inode,
582 inode_get_atime(d_inode(upperpath.dentry)));
583 }
584 }
585 return 0;
586}
587
588static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
589 u64 start, u64 len)
590{
591 int err;
592 struct inode *realinode = ovl_inode_realdata(inode);
593 const struct cred *old_cred;
594
595 if (!realinode)
596 return -EIO;
597
598 if (!realinode->i_op->fiemap)
599 return -EOPNOTSUPP;
600
601 old_cred = ovl_override_creds(inode->i_sb);
602 err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
603 ovl_revert_creds(old_cred);
604
605 return err;
606}
607
608/*
609 * Work around the fact that security_file_ioctl() takes a file argument.
610 * Introducing security_inode_fileattr_get/set() hooks would solve this issue
611 * properly.
612 */
613static int ovl_security_fileattr(const struct path *realpath, struct fileattr *fa,
614 bool set)
615{
616 struct file *file;
617 unsigned int cmd;
618 int err;
619 unsigned int flags;
620
621 flags = O_RDONLY;
622 if (force_o_largefile())
623 flags |= O_LARGEFILE;
624
625 file = dentry_open(realpath, flags, current_cred());
626 if (IS_ERR(file))
627 return PTR_ERR(file);
628
629 if (set)
630 cmd = fa->fsx_valid ? FS_IOC_FSSETXATTR : FS_IOC_SETFLAGS;
631 else
632 cmd = fa->fsx_valid ? FS_IOC_FSGETXATTR : FS_IOC_GETFLAGS;
633
634 err = security_file_ioctl(file, cmd, 0);
635 fput(file);
636
637 return err;
638}
639
640int ovl_real_fileattr_set(const struct path *realpath, struct fileattr *fa)
641{
642 int err;
643
644 err = ovl_security_fileattr(realpath, fa, true);
645 if (err)
646 return err;
647
648 return vfs_fileattr_set(mnt_idmap(realpath->mnt), realpath->dentry, fa);
649}
650
651int ovl_fileattr_set(struct mnt_idmap *idmap,
652 struct dentry *dentry, struct fileattr *fa)
653{
654 struct inode *inode = d_inode(dentry);
655 struct path upperpath;
656 const struct cred *old_cred;
657 unsigned int flags;
658 int err;
659
660 err = ovl_copy_up(dentry);
661 if (!err) {
662 ovl_path_real(dentry, &upperpath);
663
664 err = ovl_want_write(dentry);
665 if (err)
666 goto out;
667
668 old_cred = ovl_override_creds(inode->i_sb);
669 /*
670 * Store immutable/append-only flags in xattr and clear them
671 * in upper fileattr (in case they were set by older kernel)
672 * so children of "ovl-immutable" directories lower aliases of
673 * "ovl-immutable" hardlinks could be copied up.
674 * Clear xattr when flags are cleared.
675 */
676 err = ovl_set_protattr(inode, upperpath.dentry, fa);
677 if (!err)
678 err = ovl_real_fileattr_set(&upperpath, fa);
679 ovl_revert_creds(old_cred);
680 ovl_drop_write(dentry);
681
682 /*
683 * Merge real inode flags with inode flags read from
684 * overlay.protattr xattr
685 */
686 flags = ovl_inode_real(inode)->i_flags & OVL_COPY_I_FLAGS_MASK;
687
688 BUILD_BUG_ON(OVL_PROT_I_FLAGS_MASK & ~OVL_COPY_I_FLAGS_MASK);
689 flags |= inode->i_flags & OVL_PROT_I_FLAGS_MASK;
690 inode_set_flags(inode, flags, OVL_COPY_I_FLAGS_MASK);
691
692 /* Update ctime */
693 ovl_copyattr(inode);
694 }
695out:
696 return err;
697}
698
699/* Convert inode protection flags to fileattr flags */
700static void ovl_fileattr_prot_flags(struct inode *inode, struct fileattr *fa)
701{
702 BUILD_BUG_ON(OVL_PROT_FS_FLAGS_MASK & ~FS_COMMON_FL);
703 BUILD_BUG_ON(OVL_PROT_FSX_FLAGS_MASK & ~FS_XFLAG_COMMON);
704
705 if (inode->i_flags & S_APPEND) {
706 fa->flags |= FS_APPEND_FL;
707 fa->fsx_xflags |= FS_XFLAG_APPEND;
708 }
709 if (inode->i_flags & S_IMMUTABLE) {
710 fa->flags |= FS_IMMUTABLE_FL;
711 fa->fsx_xflags |= FS_XFLAG_IMMUTABLE;
712 }
713}
714
715int ovl_real_fileattr_get(const struct path *realpath, struct fileattr *fa)
716{
717 int err;
718
719 err = ovl_security_fileattr(realpath, fa, false);
720 if (err)
721 return err;
722
723 err = vfs_fileattr_get(realpath->dentry, fa);
724 if (err == -ENOIOCTLCMD)
725 err = -ENOTTY;
726 return err;
727}
728
729int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa)
730{
731 struct inode *inode = d_inode(dentry);
732 struct path realpath;
733 const struct cred *old_cred;
734 int err;
735
736 ovl_path_real(dentry, &realpath);
737
738 old_cred = ovl_override_creds(inode->i_sb);
739 err = ovl_real_fileattr_get(&realpath, fa);
740 ovl_fileattr_prot_flags(inode, fa);
741 ovl_revert_creds(old_cred);
742
743 return err;
744}
745
746static const struct inode_operations ovl_file_inode_operations = {
747 .setattr = ovl_setattr,
748 .permission = ovl_permission,
749 .getattr = ovl_getattr,
750 .listxattr = ovl_listxattr,
751 .get_inode_acl = ovl_get_inode_acl,
752 .get_acl = ovl_get_acl,
753 .set_acl = ovl_set_acl,
754 .update_time = ovl_update_time,
755 .fiemap = ovl_fiemap,
756 .fileattr_get = ovl_fileattr_get,
757 .fileattr_set = ovl_fileattr_set,
758};
759
760static const struct inode_operations ovl_symlink_inode_operations = {
761 .setattr = ovl_setattr,
762 .get_link = ovl_get_link,
763 .getattr = ovl_getattr,
764 .listxattr = ovl_listxattr,
765 .update_time = ovl_update_time,
766};
767
768static const struct inode_operations ovl_special_inode_operations = {
769 .setattr = ovl_setattr,
770 .permission = ovl_permission,
771 .getattr = ovl_getattr,
772 .listxattr = ovl_listxattr,
773 .get_inode_acl = ovl_get_inode_acl,
774 .get_acl = ovl_get_acl,
775 .set_acl = ovl_set_acl,
776 .update_time = ovl_update_time,
777};
778
779static const struct address_space_operations ovl_aops = {
780 /* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
781 .direct_IO = noop_direct_IO,
782};
783
784/*
785 * It is possible to stack overlayfs instance on top of another
786 * overlayfs instance as lower layer. We need to annotate the
787 * stackable i_mutex locks according to stack level of the super
788 * block instance. An overlayfs instance can never be in stack
789 * depth 0 (there is always a real fs below it). An overlayfs
790 * inode lock will use the lockdep annotation ovl_i_mutex_key[depth].
791 *
792 * For example, here is a snip from /proc/lockdep_chains after
793 * dir_iterate of nested overlayfs:
794 *
795 * [...] &ovl_i_mutex_dir_key[depth] (stack_depth=2)
796 * [...] &ovl_i_mutex_dir_key[depth]#2 (stack_depth=1)
797 * [...] &type->i_mutex_dir_key (stack_depth=0)
798 *
799 * Locking order w.r.t ovl_want_write() is important for nested overlayfs.
800 *
801 * This chain is valid:
802 * - inode->i_rwsem (inode_lock[2])
803 * - upper_mnt->mnt_sb->s_writers (ovl_want_write[0])
804 * - OVL_I(inode)->lock (ovl_inode_lock[2])
805 * - OVL_I(lowerinode)->lock (ovl_inode_lock[1])
806 *
807 * And this chain is valid:
808 * - inode->i_rwsem (inode_lock[2])
809 * - OVL_I(inode)->lock (ovl_inode_lock[2])
810 * - lowerinode->i_rwsem (inode_lock[1])
811 * - OVL_I(lowerinode)->lock (ovl_inode_lock[1])
812 *
813 * But lowerinode->i_rwsem SHOULD NOT be acquired while ovl_want_write() is
814 * held, because it is in reverse order of the non-nested case using the same
815 * upper fs:
816 * - inode->i_rwsem (inode_lock[1])
817 * - upper_mnt->mnt_sb->s_writers (ovl_want_write[0])
818 * - OVL_I(inode)->lock (ovl_inode_lock[1])
819 */
820#define OVL_MAX_NESTING FILESYSTEM_MAX_STACK_DEPTH
821
822static inline void ovl_lockdep_annotate_inode_mutex_key(struct inode *inode)
823{
824#ifdef CONFIG_LOCKDEP
825 static struct lock_class_key ovl_i_mutex_key[OVL_MAX_NESTING];
826 static struct lock_class_key ovl_i_mutex_dir_key[OVL_MAX_NESTING];
827 static struct lock_class_key ovl_i_lock_key[OVL_MAX_NESTING];
828
829 int depth = inode->i_sb->s_stack_depth - 1;
830
831 if (WARN_ON_ONCE(depth < 0 || depth >= OVL_MAX_NESTING))
832 depth = 0;
833
834 if (S_ISDIR(inode->i_mode))
835 lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_dir_key[depth]);
836 else
837 lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_key[depth]);
838
839 lockdep_set_class(&OVL_I(inode)->lock, &ovl_i_lock_key[depth]);
840#endif
841}
842
843static void ovl_next_ino(struct inode *inode)
844{
845 struct ovl_fs *ofs = OVL_FS(inode->i_sb);
846
847 inode->i_ino = atomic_long_inc_return(&ofs->last_ino);
848 if (unlikely(!inode->i_ino))
849 inode->i_ino = atomic_long_inc_return(&ofs->last_ino);
850}
851
852static void ovl_map_ino(struct inode *inode, unsigned long ino, int fsid)
853{
854 struct ovl_fs *ofs = OVL_FS(inode->i_sb);
855 int xinobits = ovl_xino_bits(ofs);
856 unsigned int xinoshift = 64 - xinobits;
857
858 /*
859 * When d_ino is consistent with st_ino (samefs or i_ino has enough
860 * bits to encode layer), set the same value used for st_ino to i_ino,
861 * so inode number exposed via /proc/locks and a like will be
862 * consistent with d_ino and st_ino values. An i_ino value inconsistent
863 * with d_ino also causes nfsd readdirplus to fail.
864 */
865 inode->i_ino = ino;
866 if (ovl_same_fs(ofs)) {
867 return;
868 } else if (xinobits && likely(!(ino >> xinoshift))) {
869 inode->i_ino |= (unsigned long)fsid << (xinoshift + 1);
870 return;
871 }
872
873 /*
874 * For directory inodes on non-samefs with xino disabled or xino
875 * overflow, we allocate a non-persistent inode number, to be used for
876 * resolving st_ino collisions in ovl_map_dev_ino().
877 *
878 * To avoid ino collision with legitimate xino values from upper
879 * layer (fsid 0), use the lowest xinobit to map the non
880 * persistent inode numbers to the unified st_ino address space.
881 */
882 if (S_ISDIR(inode->i_mode)) {
883 ovl_next_ino(inode);
884 if (xinobits) {
885 inode->i_ino &= ~0UL >> xinobits;
886 inode->i_ino |= 1UL << xinoshift;
887 }
888 }
889}
890
891void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
892 unsigned long ino, int fsid)
893{
894 struct inode *realinode;
895 struct ovl_inode *oi = OVL_I(inode);
896
897 oi->__upperdentry = oip->upperdentry;
898 oi->oe = oip->oe;
899 oi->redirect = oip->redirect;
900 oi->lowerdata_redirect = oip->lowerdata_redirect;
901
902 realinode = ovl_inode_real(inode);
903 ovl_copyattr(inode);
904 ovl_copyflags(realinode, inode);
905 ovl_map_ino(inode, ino, fsid);
906}
907
908static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev)
909{
910 inode->i_mode = mode;
911 inode->i_flags |= S_NOCMTIME;
912#ifdef CONFIG_FS_POSIX_ACL
913 inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE;
914#endif
915
916 ovl_lockdep_annotate_inode_mutex_key(inode);
917
918 switch (mode & S_IFMT) {
919 case S_IFREG:
920 inode->i_op = &ovl_file_inode_operations;
921 inode->i_fop = &ovl_file_operations;
922 inode->i_mapping->a_ops = &ovl_aops;
923 break;
924
925 case S_IFDIR:
926 inode->i_op = &ovl_dir_inode_operations;
927 inode->i_fop = &ovl_dir_operations;
928 break;
929
930 case S_IFLNK:
931 inode->i_op = &ovl_symlink_inode_operations;
932 break;
933
934 default:
935 inode->i_op = &ovl_special_inode_operations;
936 init_special_inode(inode, mode, rdev);
937 break;
938 }
939}
940
941/*
942 * With inodes index enabled, an overlay inode nlink counts the union of upper
943 * hardlinks and non-covered lower hardlinks. During the lifetime of a non-pure
944 * upper inode, the following nlink modifying operations can happen:
945 *
946 * 1. Lower hardlink copy up
947 * 2. Upper hardlink created, unlinked or renamed over
948 * 3. Lower hardlink whiteout or renamed over
949 *
950 * For the first, copy up case, the union nlink does not change, whether the
951 * operation succeeds or fails, but the upper inode nlink may change.
952 * Therefore, before copy up, we store the union nlink value relative to the
953 * lower inode nlink in the index inode xattr .overlay.nlink.
954 *
955 * For the second, upper hardlink case, the union nlink should be incremented
956 * or decremented IFF the operation succeeds, aligned with nlink change of the
957 * upper inode. Therefore, before link/unlink/rename, we store the union nlink
958 * value relative to the upper inode nlink in the index inode.
959 *
960 * For the last, lower cover up case, we simplify things by preceding the
961 * whiteout or cover up with copy up. This makes sure that there is an index
962 * upper inode where the nlink xattr can be stored before the copied up upper
963 * entry is unlink.
964 */
965#define OVL_NLINK_ADD_UPPER (1 << 0)
966
967/*
968 * On-disk format for indexed nlink:
969 *
970 * nlink relative to the upper inode - "U[+-]NUM"
971 * nlink relative to the lower inode - "L[+-]NUM"
972 */
973
974static int ovl_set_nlink_common(struct dentry *dentry,
975 struct dentry *realdentry, const char *format)
976{
977 struct inode *inode = d_inode(dentry);
978 struct inode *realinode = d_inode(realdentry);
979 char buf[13];
980 int len;
981
982 len = snprintf(buf, sizeof(buf), format,
983 (int) (inode->i_nlink - realinode->i_nlink));
984
985 if (WARN_ON(len >= sizeof(buf)))
986 return -EIO;
987
988 return ovl_setxattr(OVL_FS(inode->i_sb), ovl_dentry_upper(dentry),
989 OVL_XATTR_NLINK, buf, len);
990}
991
992int ovl_set_nlink_upper(struct dentry *dentry)
993{
994 return ovl_set_nlink_common(dentry, ovl_dentry_upper(dentry), "U%+i");
995}
996
997int ovl_set_nlink_lower(struct dentry *dentry)
998{
999 return ovl_set_nlink_common(dentry, ovl_dentry_lower(dentry), "L%+i");
1000}
1001
1002unsigned int ovl_get_nlink(struct ovl_fs *ofs, struct dentry *lowerdentry,
1003 struct dentry *upperdentry,
1004 unsigned int fallback)
1005{
1006 int nlink_diff;
1007 int nlink;
1008 char buf[13];
1009 int err;
1010
1011 if (!lowerdentry || !upperdentry || d_inode(lowerdentry)->i_nlink == 1)
1012 return fallback;
1013
1014 err = ovl_getxattr_upper(ofs, upperdentry, OVL_XATTR_NLINK,
1015 &buf, sizeof(buf) - 1);
1016 if (err < 0)
1017 goto fail;
1018
1019 buf[err] = '\0';
1020 if ((buf[0] != 'L' && buf[0] != 'U') ||
1021 (buf[1] != '+' && buf[1] != '-'))
1022 goto fail;
1023
1024 err = kstrtoint(buf + 1, 10, &nlink_diff);
1025 if (err < 0)
1026 goto fail;
1027
1028 nlink = d_inode(buf[0] == 'L' ? lowerdentry : upperdentry)->i_nlink;
1029 nlink += nlink_diff;
1030
1031 if (nlink <= 0)
1032 goto fail;
1033
1034 return nlink;
1035
1036fail:
1037 pr_warn_ratelimited("failed to get index nlink (%pd2, err=%i)\n",
1038 upperdentry, err);
1039 return fallback;
1040}
1041
1042struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev)
1043{
1044 struct inode *inode;
1045
1046 inode = new_inode(sb);
1047 if (inode)
1048 ovl_fill_inode(inode, mode, rdev);
1049
1050 return inode;
1051}
1052
1053static int ovl_inode_test(struct inode *inode, void *data)
1054{
1055 return inode->i_private == data;
1056}
1057
1058static int ovl_inode_set(struct inode *inode, void *data)
1059{
1060 inode->i_private = data;
1061 return 0;
1062}
1063
1064static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
1065 struct dentry *upperdentry, bool strict)
1066{
1067 /*
1068 * For directories, @strict verify from lookup path performs consistency
1069 * checks, so NULL lower/upper in dentry must match NULL lower/upper in
1070 * inode. Non @strict verify from NFS handle decode path passes NULL for
1071 * 'unknown' lower/upper.
1072 */
1073 if (S_ISDIR(inode->i_mode) && strict) {
1074 /* Real lower dir moved to upper layer under us? */
1075 if (!lowerdentry && ovl_inode_lower(inode))
1076 return false;
1077
1078 /* Lookup of an uncovered redirect origin? */
1079 if (!upperdentry && ovl_inode_upper(inode))
1080 return false;
1081 }
1082
1083 /*
1084 * Allow non-NULL lower inode in ovl_inode even if lowerdentry is NULL.
1085 * This happens when finding a copied up overlay inode for a renamed
1086 * or hardlinked overlay dentry and lower dentry cannot be followed
1087 * by origin because lower fs does not support file handles.
1088 */
1089 if (lowerdentry && ovl_inode_lower(inode) != d_inode(lowerdentry))
1090 return false;
1091
1092 /*
1093 * Allow non-NULL __upperdentry in inode even if upperdentry is NULL.
1094 * This happens when finding a lower alias for a copied up hard link.
1095 */
1096 if (upperdentry && ovl_inode_upper(inode) != d_inode(upperdentry))
1097 return false;
1098
1099 return true;
1100}
1101
1102struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
1103 bool is_upper)
1104{
1105 struct inode *inode, *key = d_inode(real);
1106
1107 inode = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
1108 if (!inode)
1109 return NULL;
1110
1111 if (!ovl_verify_inode(inode, is_upper ? NULL : real,
1112 is_upper ? real : NULL, false)) {
1113 iput(inode);
1114 return ERR_PTR(-ESTALE);
1115 }
1116
1117 return inode;
1118}
1119
1120bool ovl_lookup_trap_inode(struct super_block *sb, struct dentry *dir)
1121{
1122 struct inode *key = d_inode(dir);
1123 struct inode *trap;
1124 bool res;
1125
1126 trap = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
1127 if (!trap)
1128 return false;
1129
1130 res = IS_DEADDIR(trap) && !ovl_inode_upper(trap) &&
1131 !ovl_inode_lower(trap);
1132
1133 iput(trap);
1134 return res;
1135}
1136
1137/*
1138 * Create an inode cache entry for layer root dir, that will intentionally
1139 * fail ovl_verify_inode(), so any lookup that will find some layer root
1140 * will fail.
1141 */
1142struct inode *ovl_get_trap_inode(struct super_block *sb, struct dentry *dir)
1143{
1144 struct inode *key = d_inode(dir);
1145 struct inode *trap;
1146
1147 if (!d_is_dir(dir))
1148 return ERR_PTR(-ENOTDIR);
1149
1150 trap = iget5_locked(sb, (unsigned long) key, ovl_inode_test,
1151 ovl_inode_set, key);
1152 if (!trap)
1153 return ERR_PTR(-ENOMEM);
1154
1155 if (!(trap->i_state & I_NEW)) {
1156 /* Conflicting layer roots? */
1157 iput(trap);
1158 return ERR_PTR(-ELOOP);
1159 }
1160
1161 trap->i_mode = S_IFDIR;
1162 trap->i_flags = S_DEAD;
1163 unlock_new_inode(trap);
1164
1165 return trap;
1166}
1167
1168/*
1169 * Does overlay inode need to be hashed by lower inode?
1170 */
1171static bool ovl_hash_bylower(struct super_block *sb, struct dentry *upper,
1172 struct dentry *lower, bool index)
1173{
1174 struct ovl_fs *ofs = OVL_FS(sb);
1175
1176 /* No, if pure upper */
1177 if (!lower)
1178 return false;
1179
1180 /* Yes, if already indexed */
1181 if (index)
1182 return true;
1183
1184 /* Yes, if won't be copied up */
1185 if (!ovl_upper_mnt(ofs))
1186 return true;
1187
1188 /* No, if lower hardlink is or will be broken on copy up */
1189 if ((upper || !ovl_indexdir(sb)) &&
1190 !d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
1191 return false;
1192
1193 /* No, if non-indexed upper with NFS export */
1194 if (ofs->config.nfs_export && upper)
1195 return false;
1196
1197 /* Otherwise, hash by lower inode for fsnotify */
1198 return true;
1199}
1200
1201static struct inode *ovl_iget5(struct super_block *sb, struct inode *newinode,
1202 struct inode *key)
1203{
1204 return newinode ? inode_insert5(newinode, (unsigned long) key,
1205 ovl_inode_test, ovl_inode_set, key) :
1206 iget5_locked(sb, (unsigned long) key,
1207 ovl_inode_test, ovl_inode_set, key);
1208}
1209
1210struct inode *ovl_get_inode(struct super_block *sb,
1211 struct ovl_inode_params *oip)
1212{
1213 struct ovl_fs *ofs = OVL_FS(sb);
1214 struct dentry *upperdentry = oip->upperdentry;
1215 struct ovl_path *lowerpath = ovl_lowerpath(oip->oe);
1216 struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
1217 struct inode *inode;
1218 struct dentry *lowerdentry = lowerpath ? lowerpath->dentry : NULL;
1219 struct path realpath = {
1220 .dentry = upperdentry ?: lowerdentry,
1221 .mnt = upperdentry ? ovl_upper_mnt(ofs) : lowerpath->layer->mnt,
1222 };
1223 bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry,
1224 oip->index);
1225 int fsid = bylower ? lowerpath->layer->fsid : 0;
1226 bool is_dir;
1227 unsigned long ino = 0;
1228 int err = oip->newinode ? -EEXIST : -ENOMEM;
1229
1230 if (!realinode)
1231 realinode = d_inode(lowerdentry);
1232
1233 /*
1234 * Copy up origin (lower) may exist for non-indexed upper, but we must
1235 * not use lower as hash key if this is a broken hardlink.
1236 */
1237 is_dir = S_ISDIR(realinode->i_mode);
1238 if (upperdentry || bylower) {
1239 struct inode *key = d_inode(bylower ? lowerdentry :
1240 upperdentry);
1241 unsigned int nlink = is_dir ? 1 : realinode->i_nlink;
1242
1243 inode = ovl_iget5(sb, oip->newinode, key);
1244 if (!inode)
1245 goto out_err;
1246 if (!(inode->i_state & I_NEW)) {
1247 /*
1248 * Verify that the underlying files stored in the inode
1249 * match those in the dentry.
1250 */
1251 if (!ovl_verify_inode(inode, lowerdentry, upperdentry,
1252 true)) {
1253 iput(inode);
1254 err = -ESTALE;
1255 goto out_err;
1256 }
1257
1258 dput(upperdentry);
1259 ovl_free_entry(oip->oe);
1260 kfree(oip->redirect);
1261 kfree(oip->lowerdata_redirect);
1262 goto out;
1263 }
1264
1265 /* Recalculate nlink for non-dir due to indexing */
1266 if (!is_dir)
1267 nlink = ovl_get_nlink(ofs, lowerdentry, upperdentry,
1268 nlink);
1269 set_nlink(inode, nlink);
1270 ino = key->i_ino;
1271 } else {
1272 /* Lower hardlink that will be broken on copy up */
1273 inode = new_inode(sb);
1274 if (!inode) {
1275 err = -ENOMEM;
1276 goto out_err;
1277 }
1278 ino = realinode->i_ino;
1279 fsid = lowerpath->layer->fsid;
1280 }
1281 ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev);
1282 ovl_inode_init(inode, oip, ino, fsid);
1283
1284 if (upperdentry && ovl_is_impuredir(sb, upperdentry))
1285 ovl_set_flag(OVL_IMPURE, inode);
1286
1287 if (oip->index)
1288 ovl_set_flag(OVL_INDEX, inode);
1289
1290 if (bylower)
1291 ovl_set_flag(OVL_CONST_INO, inode);
1292
1293 /* Check for non-merge dir that may have whiteouts */
1294 if (is_dir) {
1295 if (((upperdentry && lowerdentry) || ovl_numlower(oip->oe) > 1) ||
1296 ovl_path_check_origin_xattr(ofs, &realpath)) {
1297 ovl_set_flag(OVL_WHITEOUTS, inode);
1298 }
1299 }
1300
1301 /* Check for immutable/append-only inode flags in xattr */
1302 if (upperdentry)
1303 ovl_check_protattr(inode, upperdentry);
1304
1305 if (inode->i_state & I_NEW)
1306 unlock_new_inode(inode);
1307out:
1308 return inode;
1309
1310out_err:
1311 pr_warn_ratelimited("failed to get inode (%i)\n", err);
1312 inode = ERR_PTR(err);
1313 goto out;
1314}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 *
4 * Copyright (C) 2011 Novell Inc.
5 */
6
7#include <linux/fs.h>
8#include <linux/slab.h>
9#include <linux/cred.h>
10#include <linux/xattr.h>
11#include <linux/posix_acl.h>
12#include <linux/ratelimit.h>
13#include <linux/fiemap.h>
14#include <linux/fileattr.h>
15#include <linux/security.h>
16#include <linux/namei.h>
17#include <linux/posix_acl.h>
18#include <linux/posix_acl_xattr.h>
19#include "overlayfs.h"
20
21
22int ovl_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
23 struct iattr *attr)
24{
25 int err;
26 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
27 bool full_copy_up = false;
28 struct dentry *upperdentry;
29 const struct cred *old_cred;
30
31 err = setattr_prepare(&nop_mnt_idmap, dentry, attr);
32 if (err)
33 return err;
34
35 if (attr->ia_valid & ATTR_SIZE) {
36 /* Truncate should trigger data copy up as well */
37 full_copy_up = true;
38 }
39
40 if (!full_copy_up)
41 err = ovl_copy_up(dentry);
42 else
43 err = ovl_copy_up_with_data(dentry);
44 if (!err) {
45 struct inode *winode = NULL;
46
47 upperdentry = ovl_dentry_upper(dentry);
48
49 if (attr->ia_valid & ATTR_SIZE) {
50 winode = d_inode(upperdentry);
51 err = get_write_access(winode);
52 if (err)
53 goto out;
54 }
55
56 if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
57 attr->ia_valid &= ~ATTR_MODE;
58
59 /*
60 * We might have to translate ovl file into real file object
61 * once use cases emerge. For now, simply don't let underlying
62 * filesystem rely on attr->ia_file
63 */
64 attr->ia_valid &= ~ATTR_FILE;
65
66 /*
67 * If open(O_TRUNC) is done, VFS calls ->setattr with ATTR_OPEN
68 * set. Overlayfs does not pass O_TRUNC flag to underlying
69 * filesystem during open -> do not pass ATTR_OPEN. This
70 * disables optimization in fuse which assumes open(O_TRUNC)
71 * already set file size to 0. But we never passed O_TRUNC to
72 * fuse. So by clearing ATTR_OPEN, fuse will be forced to send
73 * setattr request to server.
74 */
75 attr->ia_valid &= ~ATTR_OPEN;
76
77 err = ovl_want_write(dentry);
78 if (err)
79 goto out_put_write;
80
81 inode_lock(upperdentry->d_inode);
82 old_cred = ovl_override_creds(dentry->d_sb);
83 err = ovl_do_notify_change(ofs, upperdentry, attr);
84 revert_creds(old_cred);
85 if (!err)
86 ovl_copyattr(dentry->d_inode);
87 inode_unlock(upperdentry->d_inode);
88 ovl_drop_write(dentry);
89
90out_put_write:
91 if (winode)
92 put_write_access(winode);
93 }
94out:
95 return err;
96}
97
98static void ovl_map_dev_ino(struct dentry *dentry, struct kstat *stat, int fsid)
99{
100 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
101 bool samefs = ovl_same_fs(ofs);
102 unsigned int xinobits = ovl_xino_bits(ofs);
103 unsigned int xinoshift = 64 - xinobits;
104
105 if (samefs) {
106 /*
107 * When all layers are on the same fs, all real inode
108 * number are unique, so we use the overlay st_dev,
109 * which is friendly to du -x.
110 */
111 stat->dev = dentry->d_sb->s_dev;
112 return;
113 } else if (xinobits) {
114 /*
115 * All inode numbers of underlying fs should not be using the
116 * high xinobits, so we use high xinobits to partition the
117 * overlay st_ino address space. The high bits holds the fsid
118 * (upper fsid is 0). The lowest xinobit is reserved for mapping
119 * the non-persistent inode numbers range in case of overflow.
120 * This way all overlay inode numbers are unique and use the
121 * overlay st_dev.
122 */
123 if (likely(!(stat->ino >> xinoshift))) {
124 stat->ino |= ((u64)fsid) << (xinoshift + 1);
125 stat->dev = dentry->d_sb->s_dev;
126 return;
127 } else if (ovl_xino_warn(ofs)) {
128 pr_warn_ratelimited("inode number too big (%pd2, ino=%llu, xinobits=%d)\n",
129 dentry, stat->ino, xinobits);
130 }
131 }
132
133 /* The inode could not be mapped to a unified st_ino address space */
134 if (S_ISDIR(dentry->d_inode->i_mode)) {
135 /*
136 * Always use the overlay st_dev for directories, so 'find
137 * -xdev' will scan the entire overlay mount and won't cross the
138 * overlay mount boundaries.
139 *
140 * If not all layers are on the same fs the pair {real st_ino;
141 * overlay st_dev} is not unique, so use the non persistent
142 * overlay st_ino for directories.
143 */
144 stat->dev = dentry->d_sb->s_dev;
145 stat->ino = dentry->d_inode->i_ino;
146 } else {
147 /*
148 * For non-samefs setup, if we cannot map all layers st_ino
149 * to a unified address space, we need to make sure that st_dev
150 * is unique per underlying fs, so we use the unique anonymous
151 * bdev assigned to the underlying fs.
152 */
153 stat->dev = ofs->fs[fsid].pseudo_dev;
154 }
155}
156
157int ovl_getattr(struct mnt_idmap *idmap, const struct path *path,
158 struct kstat *stat, u32 request_mask, unsigned int flags)
159{
160 struct dentry *dentry = path->dentry;
161 enum ovl_path_type type;
162 struct path realpath;
163 const struct cred *old_cred;
164 struct inode *inode = d_inode(dentry);
165 bool is_dir = S_ISDIR(inode->i_mode);
166 int fsid = 0;
167 int err;
168 bool metacopy_blocks = false;
169
170 metacopy_blocks = ovl_is_metacopy_dentry(dentry);
171
172 type = ovl_path_real(dentry, &realpath);
173 old_cred = ovl_override_creds(dentry->d_sb);
174 err = ovl_do_getattr(&realpath, stat, request_mask, flags);
175 if (err)
176 goto out;
177
178 /* Report the effective immutable/append-only STATX flags */
179 generic_fill_statx_attr(inode, stat);
180
181 /*
182 * For non-dir or same fs, we use st_ino of the copy up origin.
183 * This guaranties constant st_dev/st_ino across copy up.
184 * With xino feature and non-samefs, we use st_ino of the copy up
185 * origin masked with high bits that represent the layer id.
186 *
187 * If lower filesystem supports NFS file handles, this also guaranties
188 * persistent st_ino across mount cycle.
189 */
190 if (!is_dir || ovl_same_dev(OVL_FS(dentry->d_sb))) {
191 if (!OVL_TYPE_UPPER(type)) {
192 fsid = ovl_layer_lower(dentry)->fsid;
193 } else if (OVL_TYPE_ORIGIN(type)) {
194 struct kstat lowerstat;
195 u32 lowermask = STATX_INO | STATX_BLOCKS |
196 (!is_dir ? STATX_NLINK : 0);
197
198 ovl_path_lower(dentry, &realpath);
199 err = ovl_do_getattr(&realpath, &lowerstat, lowermask,
200 flags);
201 if (err)
202 goto out;
203
204 /*
205 * Lower hardlinks may be broken on copy up to different
206 * upper files, so we cannot use the lower origin st_ino
207 * for those different files, even for the same fs case.
208 *
209 * Similarly, several redirected dirs can point to the
210 * same dir on a lower layer. With the "verify_lower"
211 * feature, we do not use the lower origin st_ino, if
212 * we haven't verified that this redirect is unique.
213 *
214 * With inodes index enabled, it is safe to use st_ino
215 * of an indexed origin. The index validates that the
216 * upper hardlink is not broken and that a redirected
217 * dir is the only redirect to that origin.
218 */
219 if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) ||
220 (!ovl_verify_lower(dentry->d_sb) &&
221 (is_dir || lowerstat.nlink == 1))) {
222 fsid = ovl_layer_lower(dentry)->fsid;
223 stat->ino = lowerstat.ino;
224 }
225
226 /*
227 * If we are querying a metacopy dentry and lower
228 * dentry is data dentry, then use the blocks we
229 * queried just now. We don't have to do additional
230 * vfs_getattr(). If lower itself is metacopy, then
231 * additional vfs_getattr() is unavoidable.
232 */
233 if (metacopy_blocks &&
234 realpath.dentry == ovl_dentry_lowerdata(dentry)) {
235 stat->blocks = lowerstat.blocks;
236 metacopy_blocks = false;
237 }
238 }
239
240 if (metacopy_blocks) {
241 /*
242 * If lower is not same as lowerdata or if there was
243 * no origin on upper, we can end up here.
244 * With lazy lowerdata lookup, guess lowerdata blocks
245 * from size to avoid lowerdata lookup on stat(2).
246 */
247 struct kstat lowerdatastat;
248 u32 lowermask = STATX_BLOCKS;
249
250 ovl_path_lowerdata(dentry, &realpath);
251 if (realpath.dentry) {
252 err = ovl_do_getattr(&realpath, &lowerdatastat,
253 lowermask, flags);
254 if (err)
255 goto out;
256 } else {
257 lowerdatastat.blocks =
258 round_up(stat->size, stat->blksize) >> 9;
259 }
260 stat->blocks = lowerdatastat.blocks;
261 }
262 }
263
264 ovl_map_dev_ino(dentry, stat, fsid);
265
266 /*
267 * It's probably not worth it to count subdirs to get the
268 * correct link count. nlink=1 seems to pacify 'find' and
269 * other utilities.
270 */
271 if (is_dir && OVL_TYPE_MERGE(type))
272 stat->nlink = 1;
273
274 /*
275 * Return the overlay inode nlinks for indexed upper inodes.
276 * Overlay inode nlink counts the union of the upper hardlinks
277 * and non-covered lower hardlinks. It does not include the upper
278 * index hardlink.
279 */
280 if (!is_dir && ovl_test_flag(OVL_INDEX, d_inode(dentry)))
281 stat->nlink = dentry->d_inode->i_nlink;
282
283out:
284 revert_creds(old_cred);
285
286 return err;
287}
288
289int ovl_permission(struct mnt_idmap *idmap,
290 struct inode *inode, int mask)
291{
292 struct inode *upperinode = ovl_inode_upper(inode);
293 struct inode *realinode;
294 struct path realpath;
295 const struct cred *old_cred;
296 int err;
297
298 /* Careful in RCU walk mode */
299 realinode = ovl_i_path_real(inode, &realpath);
300 if (!realinode) {
301 WARN_ON(!(mask & MAY_NOT_BLOCK));
302 return -ECHILD;
303 }
304
305 /*
306 * Check overlay inode with the creds of task and underlying inode
307 * with creds of mounter
308 */
309 err = generic_permission(&nop_mnt_idmap, inode, mask);
310 if (err)
311 return err;
312
313 old_cred = ovl_override_creds(inode->i_sb);
314 if (!upperinode &&
315 !special_file(realinode->i_mode) && mask & MAY_WRITE) {
316 mask &= ~(MAY_WRITE | MAY_APPEND);
317 /* Make sure mounter can read file for copy up later */
318 mask |= MAY_READ;
319 }
320 err = inode_permission(mnt_idmap(realpath.mnt), realinode, mask);
321 revert_creds(old_cred);
322
323 return err;
324}
325
326static const char *ovl_get_link(struct dentry *dentry,
327 struct inode *inode,
328 struct delayed_call *done)
329{
330 const struct cred *old_cred;
331 const char *p;
332
333 if (!dentry)
334 return ERR_PTR(-ECHILD);
335
336 old_cred = ovl_override_creds(dentry->d_sb);
337 p = vfs_get_link(ovl_dentry_real(dentry), done);
338 revert_creds(old_cred);
339 return p;
340}
341
342#ifdef CONFIG_FS_POSIX_ACL
343/*
344 * Apply the idmapping of the layer to POSIX ACLs. The caller must pass a clone
345 * of the POSIX ACLs retrieved from the lower layer to this function to not
346 * alter the POSIX ACLs for the underlying filesystem.
347 */
348static void ovl_idmap_posix_acl(const struct inode *realinode,
349 struct mnt_idmap *idmap,
350 struct posix_acl *acl)
351{
352 struct user_namespace *fs_userns = i_user_ns(realinode);
353
354 for (unsigned int i = 0; i < acl->a_count; i++) {
355 vfsuid_t vfsuid;
356 vfsgid_t vfsgid;
357
358 struct posix_acl_entry *e = &acl->a_entries[i];
359 switch (e->e_tag) {
360 case ACL_USER:
361 vfsuid = make_vfsuid(idmap, fs_userns, e->e_uid);
362 e->e_uid = vfsuid_into_kuid(vfsuid);
363 break;
364 case ACL_GROUP:
365 vfsgid = make_vfsgid(idmap, fs_userns, e->e_gid);
366 e->e_gid = vfsgid_into_kgid(vfsgid);
367 break;
368 }
369 }
370}
371
372/*
373 * The @noperm argument is used to skip permission checking and is a temporary
374 * measure. Quoting Miklos from an earlier discussion:
375 *
376 * > So there are two paths to getting an acl:
377 * > 1) permission checking and 2) retrieving the value via getxattr(2).
378 * > This is a similar situation as reading a symlink vs. following it.
379 * > When following a symlink overlayfs always reads the link on the
380 * > underlying fs just as if it was a readlink(2) call, calling
381 * > security_inode_readlink() instead of security_inode_follow_link().
382 * > This is logical: we are reading the link from the underlying storage,
383 * > and following it on overlayfs.
384 * >
385 * > Applying the same logic to acl: we do need to call the
386 * > security_inode_getxattr() on the underlying fs, even if just want to
387 * > check permissions on overlay. This is currently not done, which is an
388 * > inconsistency.
389 * >
390 * > Maybe adding the check to ovl_get_acl() is the right way to go, but
391 * > I'm a little afraid of a performance regression. Will look into that.
392 *
393 * Until we have made a decision allow this helper to take the @noperm
394 * argument. We should hopefully be able to remove it soon.
395 */
396struct posix_acl *ovl_get_acl_path(const struct path *path,
397 const char *acl_name, bool noperm)
398{
399 struct posix_acl *real_acl, *clone;
400 struct mnt_idmap *idmap;
401 struct inode *realinode = d_inode(path->dentry);
402
403 idmap = mnt_idmap(path->mnt);
404
405 if (noperm)
406 real_acl = get_inode_acl(realinode, posix_acl_type(acl_name));
407 else
408 real_acl = vfs_get_acl(idmap, path->dentry, acl_name);
409 if (IS_ERR_OR_NULL(real_acl))
410 return real_acl;
411
412 if (!is_idmapped_mnt(path->mnt))
413 return real_acl;
414
415 /*
416 * We cannot alter the ACLs returned from the relevant layer as that
417 * would alter the cached values filesystem wide for the lower
418 * filesystem. Instead we can clone the ACLs and then apply the
419 * relevant idmapping of the layer.
420 */
421 clone = posix_acl_clone(real_acl, GFP_KERNEL);
422 posix_acl_release(real_acl); /* release original acl */
423 if (!clone)
424 return ERR_PTR(-ENOMEM);
425
426 ovl_idmap_posix_acl(realinode, idmap, clone);
427 return clone;
428}
429
430/*
431 * When the relevant layer is an idmapped mount we need to take the idmapping
432 * of the layer into account and translate any ACL_{GROUP,USER} values
433 * according to the idmapped mount.
434 *
435 * We cannot alter the ACLs returned from the relevant layer as that would
436 * alter the cached values filesystem wide for the lower filesystem. Instead we
437 * can clone the ACLs and then apply the relevant idmapping of the layer.
438 *
439 * This is obviously only relevant when idmapped layers are used.
440 */
441struct posix_acl *do_ovl_get_acl(struct mnt_idmap *idmap,
442 struct inode *inode, int type,
443 bool rcu, bool noperm)
444{
445 struct inode *realinode;
446 struct posix_acl *acl;
447 struct path realpath;
448
449 /* Careful in RCU walk mode */
450 realinode = ovl_i_path_real(inode, &realpath);
451 if (!realinode) {
452 WARN_ON(!rcu);
453 return ERR_PTR(-ECHILD);
454 }
455
456 if (!IS_POSIXACL(realinode))
457 return NULL;
458
459 if (rcu) {
460 /*
461 * If the layer is idmapped drop out of RCU path walk
462 * so we can clone the ACLs.
463 */
464 if (is_idmapped_mnt(realpath.mnt))
465 return ERR_PTR(-ECHILD);
466
467 acl = get_cached_acl_rcu(realinode, type);
468 } else {
469 const struct cred *old_cred;
470
471 old_cred = ovl_override_creds(inode->i_sb);
472 acl = ovl_get_acl_path(&realpath, posix_acl_xattr_name(type), noperm);
473 revert_creds(old_cred);
474 }
475
476 return acl;
477}
478
479static int ovl_set_or_remove_acl(struct dentry *dentry, struct inode *inode,
480 struct posix_acl *acl, int type)
481{
482 int err;
483 struct path realpath;
484 const char *acl_name;
485 const struct cred *old_cred;
486 struct ovl_fs *ofs = OVL_FS(dentry->d_sb);
487 struct dentry *upperdentry = ovl_dentry_upper(dentry);
488 struct dentry *realdentry = upperdentry ?: ovl_dentry_lower(dentry);
489
490 /*
491 * If ACL is to be removed from a lower file, check if it exists in
492 * the first place before copying it up.
493 */
494 acl_name = posix_acl_xattr_name(type);
495 if (!acl && !upperdentry) {
496 struct posix_acl *real_acl;
497
498 ovl_path_lower(dentry, &realpath);
499 old_cred = ovl_override_creds(dentry->d_sb);
500 real_acl = vfs_get_acl(mnt_idmap(realpath.mnt), realdentry,
501 acl_name);
502 revert_creds(old_cred);
503 if (IS_ERR(real_acl)) {
504 err = PTR_ERR(real_acl);
505 goto out;
506 }
507 posix_acl_release(real_acl);
508 }
509
510 if (!upperdentry) {
511 err = ovl_copy_up(dentry);
512 if (err)
513 goto out;
514
515 realdentry = ovl_dentry_upper(dentry);
516 }
517
518 err = ovl_want_write(dentry);
519 if (err)
520 goto out;
521
522 old_cred = ovl_override_creds(dentry->d_sb);
523 if (acl)
524 err = ovl_do_set_acl(ofs, realdentry, acl_name, acl);
525 else
526 err = ovl_do_remove_acl(ofs, realdentry, acl_name);
527 revert_creds(old_cred);
528 ovl_drop_write(dentry);
529
530 /* copy c/mtime */
531 ovl_copyattr(inode);
532out:
533 return err;
534}
535
536int ovl_set_acl(struct mnt_idmap *idmap, struct dentry *dentry,
537 struct posix_acl *acl, int type)
538{
539 int err;
540 struct inode *inode = d_inode(dentry);
541 struct dentry *workdir = ovl_workdir(dentry);
542 struct inode *realinode = ovl_inode_real(inode);
543
544 if (!IS_POSIXACL(d_inode(workdir)))
545 return -EOPNOTSUPP;
546 if (!realinode->i_op->set_acl)
547 return -EOPNOTSUPP;
548 if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
549 return acl ? -EACCES : 0;
550 if (!inode_owner_or_capable(&nop_mnt_idmap, inode))
551 return -EPERM;
552
553 /*
554 * Check if sgid bit needs to be cleared (actual setacl operation will
555 * be done with mounter's capabilities and so that won't do it for us).
556 */
557 if (unlikely(inode->i_mode & S_ISGID) && type == ACL_TYPE_ACCESS &&
558 !in_group_p(inode->i_gid) &&
559 !capable_wrt_inode_uidgid(&nop_mnt_idmap, inode, CAP_FSETID)) {
560 struct iattr iattr = { .ia_valid = ATTR_KILL_SGID };
561
562 err = ovl_setattr(&nop_mnt_idmap, dentry, &iattr);
563 if (err)
564 return err;
565 }
566
567 return ovl_set_or_remove_acl(dentry, inode, acl, type);
568}
569#endif
570
571int ovl_update_time(struct inode *inode, int flags)
572{
573 if (flags & S_ATIME) {
574 struct ovl_fs *ofs = OVL_FS(inode->i_sb);
575 struct path upperpath = {
576 .mnt = ovl_upper_mnt(ofs),
577 .dentry = ovl_upperdentry_dereference(OVL_I(inode)),
578 };
579
580 if (upperpath.dentry) {
581 touch_atime(&upperpath);
582 inode_set_atime_to_ts(inode,
583 inode_get_atime(d_inode(upperpath.dentry)));
584 }
585 }
586 return 0;
587}
588
589static int ovl_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
590 u64 start, u64 len)
591{
592 int err;
593 struct inode *realinode = ovl_inode_realdata(inode);
594 const struct cred *old_cred;
595
596 if (!realinode)
597 return -EIO;
598
599 if (!realinode->i_op->fiemap)
600 return -EOPNOTSUPP;
601
602 old_cred = ovl_override_creds(inode->i_sb);
603 err = realinode->i_op->fiemap(realinode, fieinfo, start, len);
604 revert_creds(old_cred);
605
606 return err;
607}
608
609/*
610 * Work around the fact that security_file_ioctl() takes a file argument.
611 * Introducing security_inode_fileattr_get/set() hooks would solve this issue
612 * properly.
613 */
614static int ovl_security_fileattr(const struct path *realpath, struct fileattr *fa,
615 bool set)
616{
617 struct file *file;
618 unsigned int cmd;
619 int err;
620
621 file = dentry_open(realpath, O_RDONLY, current_cred());
622 if (IS_ERR(file))
623 return PTR_ERR(file);
624
625 if (set)
626 cmd = fa->fsx_valid ? FS_IOC_FSSETXATTR : FS_IOC_SETFLAGS;
627 else
628 cmd = fa->fsx_valid ? FS_IOC_FSGETXATTR : FS_IOC_GETFLAGS;
629
630 err = security_file_ioctl(file, cmd, 0);
631 fput(file);
632
633 return err;
634}
635
636int ovl_real_fileattr_set(const struct path *realpath, struct fileattr *fa)
637{
638 int err;
639
640 err = ovl_security_fileattr(realpath, fa, true);
641 if (err)
642 return err;
643
644 return vfs_fileattr_set(mnt_idmap(realpath->mnt), realpath->dentry, fa);
645}
646
647int ovl_fileattr_set(struct mnt_idmap *idmap,
648 struct dentry *dentry, struct fileattr *fa)
649{
650 struct inode *inode = d_inode(dentry);
651 struct path upperpath;
652 const struct cred *old_cred;
653 unsigned int flags;
654 int err;
655
656 err = ovl_copy_up(dentry);
657 if (!err) {
658 ovl_path_real(dentry, &upperpath);
659
660 err = ovl_want_write(dentry);
661 if (err)
662 goto out;
663
664 old_cred = ovl_override_creds(inode->i_sb);
665 /*
666 * Store immutable/append-only flags in xattr and clear them
667 * in upper fileattr (in case they were set by older kernel)
668 * so children of "ovl-immutable" directories lower aliases of
669 * "ovl-immutable" hardlinks could be copied up.
670 * Clear xattr when flags are cleared.
671 */
672 err = ovl_set_protattr(inode, upperpath.dentry, fa);
673 if (!err)
674 err = ovl_real_fileattr_set(&upperpath, fa);
675 revert_creds(old_cred);
676 ovl_drop_write(dentry);
677
678 /*
679 * Merge real inode flags with inode flags read from
680 * overlay.protattr xattr
681 */
682 flags = ovl_inode_real(inode)->i_flags & OVL_COPY_I_FLAGS_MASK;
683
684 BUILD_BUG_ON(OVL_PROT_I_FLAGS_MASK & ~OVL_COPY_I_FLAGS_MASK);
685 flags |= inode->i_flags & OVL_PROT_I_FLAGS_MASK;
686 inode_set_flags(inode, flags, OVL_COPY_I_FLAGS_MASK);
687
688 /* Update ctime */
689 ovl_copyattr(inode);
690 }
691out:
692 return err;
693}
694
695/* Convert inode protection flags to fileattr flags */
696static void ovl_fileattr_prot_flags(struct inode *inode, struct fileattr *fa)
697{
698 BUILD_BUG_ON(OVL_PROT_FS_FLAGS_MASK & ~FS_COMMON_FL);
699 BUILD_BUG_ON(OVL_PROT_FSX_FLAGS_MASK & ~FS_XFLAG_COMMON);
700
701 if (inode->i_flags & S_APPEND) {
702 fa->flags |= FS_APPEND_FL;
703 fa->fsx_xflags |= FS_XFLAG_APPEND;
704 }
705 if (inode->i_flags & S_IMMUTABLE) {
706 fa->flags |= FS_IMMUTABLE_FL;
707 fa->fsx_xflags |= FS_XFLAG_IMMUTABLE;
708 }
709}
710
711int ovl_real_fileattr_get(const struct path *realpath, struct fileattr *fa)
712{
713 int err;
714
715 err = ovl_security_fileattr(realpath, fa, false);
716 if (err)
717 return err;
718
719 err = vfs_fileattr_get(realpath->dentry, fa);
720 if (err == -ENOIOCTLCMD)
721 err = -ENOTTY;
722 return err;
723}
724
725int ovl_fileattr_get(struct dentry *dentry, struct fileattr *fa)
726{
727 struct inode *inode = d_inode(dentry);
728 struct path realpath;
729 const struct cred *old_cred;
730 int err;
731
732 ovl_path_real(dentry, &realpath);
733
734 old_cred = ovl_override_creds(inode->i_sb);
735 err = ovl_real_fileattr_get(&realpath, fa);
736 ovl_fileattr_prot_flags(inode, fa);
737 revert_creds(old_cred);
738
739 return err;
740}
741
742static const struct inode_operations ovl_file_inode_operations = {
743 .setattr = ovl_setattr,
744 .permission = ovl_permission,
745 .getattr = ovl_getattr,
746 .listxattr = ovl_listxattr,
747 .get_inode_acl = ovl_get_inode_acl,
748 .get_acl = ovl_get_acl,
749 .set_acl = ovl_set_acl,
750 .update_time = ovl_update_time,
751 .fiemap = ovl_fiemap,
752 .fileattr_get = ovl_fileattr_get,
753 .fileattr_set = ovl_fileattr_set,
754};
755
756static const struct inode_operations ovl_symlink_inode_operations = {
757 .setattr = ovl_setattr,
758 .get_link = ovl_get_link,
759 .getattr = ovl_getattr,
760 .listxattr = ovl_listxattr,
761 .update_time = ovl_update_time,
762};
763
764static const struct inode_operations ovl_special_inode_operations = {
765 .setattr = ovl_setattr,
766 .permission = ovl_permission,
767 .getattr = ovl_getattr,
768 .listxattr = ovl_listxattr,
769 .get_inode_acl = ovl_get_inode_acl,
770 .get_acl = ovl_get_acl,
771 .set_acl = ovl_set_acl,
772 .update_time = ovl_update_time,
773};
774
775static const struct address_space_operations ovl_aops = {
776 /* For O_DIRECT dentry_open() checks f_mapping->a_ops->direct_IO */
777 .direct_IO = noop_direct_IO,
778};
779
780/*
781 * It is possible to stack overlayfs instance on top of another
782 * overlayfs instance as lower layer. We need to annotate the
783 * stackable i_mutex locks according to stack level of the super
784 * block instance. An overlayfs instance can never be in stack
785 * depth 0 (there is always a real fs below it). An overlayfs
786 * inode lock will use the lockdep annotation ovl_i_mutex_key[depth].
787 *
788 * For example, here is a snip from /proc/lockdep_chains after
789 * dir_iterate of nested overlayfs:
790 *
791 * [...] &ovl_i_mutex_dir_key[depth] (stack_depth=2)
792 * [...] &ovl_i_mutex_dir_key[depth]#2 (stack_depth=1)
793 * [...] &type->i_mutex_dir_key (stack_depth=0)
794 *
795 * Locking order w.r.t ovl_want_write() is important for nested overlayfs.
796 *
797 * This chain is valid:
798 * - inode->i_rwsem (inode_lock[2])
799 * - upper_mnt->mnt_sb->s_writers (ovl_want_write[0])
800 * - OVL_I(inode)->lock (ovl_inode_lock[2])
801 * - OVL_I(lowerinode)->lock (ovl_inode_lock[1])
802 *
803 * And this chain is valid:
804 * - inode->i_rwsem (inode_lock[2])
805 * - OVL_I(inode)->lock (ovl_inode_lock[2])
806 * - lowerinode->i_rwsem (inode_lock[1])
807 * - OVL_I(lowerinode)->lock (ovl_inode_lock[1])
808 *
809 * But lowerinode->i_rwsem SHOULD NOT be acquired while ovl_want_write() is
810 * held, because it is in reverse order of the non-nested case using the same
811 * upper fs:
812 * - inode->i_rwsem (inode_lock[1])
813 * - upper_mnt->mnt_sb->s_writers (ovl_want_write[0])
814 * - OVL_I(inode)->lock (ovl_inode_lock[1])
815 */
816#define OVL_MAX_NESTING FILESYSTEM_MAX_STACK_DEPTH
817
818static inline void ovl_lockdep_annotate_inode_mutex_key(struct inode *inode)
819{
820#ifdef CONFIG_LOCKDEP
821 static struct lock_class_key ovl_i_mutex_key[OVL_MAX_NESTING];
822 static struct lock_class_key ovl_i_mutex_dir_key[OVL_MAX_NESTING];
823 static struct lock_class_key ovl_i_lock_key[OVL_MAX_NESTING];
824
825 int depth = inode->i_sb->s_stack_depth - 1;
826
827 if (WARN_ON_ONCE(depth < 0 || depth >= OVL_MAX_NESTING))
828 depth = 0;
829
830 if (S_ISDIR(inode->i_mode))
831 lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_dir_key[depth]);
832 else
833 lockdep_set_class(&inode->i_rwsem, &ovl_i_mutex_key[depth]);
834
835 lockdep_set_class(&OVL_I(inode)->lock, &ovl_i_lock_key[depth]);
836#endif
837}
838
839static void ovl_next_ino(struct inode *inode)
840{
841 struct ovl_fs *ofs = OVL_FS(inode->i_sb);
842
843 inode->i_ino = atomic_long_inc_return(&ofs->last_ino);
844 if (unlikely(!inode->i_ino))
845 inode->i_ino = atomic_long_inc_return(&ofs->last_ino);
846}
847
848static void ovl_map_ino(struct inode *inode, unsigned long ino, int fsid)
849{
850 struct ovl_fs *ofs = OVL_FS(inode->i_sb);
851 int xinobits = ovl_xino_bits(ofs);
852 unsigned int xinoshift = 64 - xinobits;
853
854 /*
855 * When d_ino is consistent with st_ino (samefs or i_ino has enough
856 * bits to encode layer), set the same value used for st_ino to i_ino,
857 * so inode number exposed via /proc/locks and a like will be
858 * consistent with d_ino and st_ino values. An i_ino value inconsistent
859 * with d_ino also causes nfsd readdirplus to fail.
860 */
861 inode->i_ino = ino;
862 if (ovl_same_fs(ofs)) {
863 return;
864 } else if (xinobits && likely(!(ino >> xinoshift))) {
865 inode->i_ino |= (unsigned long)fsid << (xinoshift + 1);
866 return;
867 }
868
869 /*
870 * For directory inodes on non-samefs with xino disabled or xino
871 * overflow, we allocate a non-persistent inode number, to be used for
872 * resolving st_ino collisions in ovl_map_dev_ino().
873 *
874 * To avoid ino collision with legitimate xino values from upper
875 * layer (fsid 0), use the lowest xinobit to map the non
876 * persistent inode numbers to the unified st_ino address space.
877 */
878 if (S_ISDIR(inode->i_mode)) {
879 ovl_next_ino(inode);
880 if (xinobits) {
881 inode->i_ino &= ~0UL >> xinobits;
882 inode->i_ino |= 1UL << xinoshift;
883 }
884 }
885}
886
887void ovl_inode_init(struct inode *inode, struct ovl_inode_params *oip,
888 unsigned long ino, int fsid)
889{
890 struct inode *realinode;
891 struct ovl_inode *oi = OVL_I(inode);
892
893 oi->__upperdentry = oip->upperdentry;
894 oi->oe = oip->oe;
895 oi->redirect = oip->redirect;
896 oi->lowerdata_redirect = oip->lowerdata_redirect;
897
898 realinode = ovl_inode_real(inode);
899 ovl_copyattr(inode);
900 ovl_copyflags(realinode, inode);
901 ovl_map_ino(inode, ino, fsid);
902}
903
904static void ovl_fill_inode(struct inode *inode, umode_t mode, dev_t rdev)
905{
906 inode->i_mode = mode;
907 inode->i_flags |= S_NOCMTIME;
908#ifdef CONFIG_FS_POSIX_ACL
909 inode->i_acl = inode->i_default_acl = ACL_DONT_CACHE;
910#endif
911
912 ovl_lockdep_annotate_inode_mutex_key(inode);
913
914 switch (mode & S_IFMT) {
915 case S_IFREG:
916 inode->i_op = &ovl_file_inode_operations;
917 inode->i_fop = &ovl_file_operations;
918 inode->i_mapping->a_ops = &ovl_aops;
919 break;
920
921 case S_IFDIR:
922 inode->i_op = &ovl_dir_inode_operations;
923 inode->i_fop = &ovl_dir_operations;
924 break;
925
926 case S_IFLNK:
927 inode->i_op = &ovl_symlink_inode_operations;
928 break;
929
930 default:
931 inode->i_op = &ovl_special_inode_operations;
932 init_special_inode(inode, mode, rdev);
933 break;
934 }
935}
936
937/*
938 * With inodes index enabled, an overlay inode nlink counts the union of upper
939 * hardlinks and non-covered lower hardlinks. During the lifetime of a non-pure
940 * upper inode, the following nlink modifying operations can happen:
941 *
942 * 1. Lower hardlink copy up
943 * 2. Upper hardlink created, unlinked or renamed over
944 * 3. Lower hardlink whiteout or renamed over
945 *
946 * For the first, copy up case, the union nlink does not change, whether the
947 * operation succeeds or fails, but the upper inode nlink may change.
948 * Therefore, before copy up, we store the union nlink value relative to the
949 * lower inode nlink in the index inode xattr .overlay.nlink.
950 *
951 * For the second, upper hardlink case, the union nlink should be incremented
952 * or decremented IFF the operation succeeds, aligned with nlink change of the
953 * upper inode. Therefore, before link/unlink/rename, we store the union nlink
954 * value relative to the upper inode nlink in the index inode.
955 *
956 * For the last, lower cover up case, we simplify things by preceding the
957 * whiteout or cover up with copy up. This makes sure that there is an index
958 * upper inode where the nlink xattr can be stored before the copied up upper
959 * entry is unlink.
960 */
961#define OVL_NLINK_ADD_UPPER (1 << 0)
962
963/*
964 * On-disk format for indexed nlink:
965 *
966 * nlink relative to the upper inode - "U[+-]NUM"
967 * nlink relative to the lower inode - "L[+-]NUM"
968 */
969
970static int ovl_set_nlink_common(struct dentry *dentry,
971 struct dentry *realdentry, const char *format)
972{
973 struct inode *inode = d_inode(dentry);
974 struct inode *realinode = d_inode(realdentry);
975 char buf[13];
976 int len;
977
978 len = snprintf(buf, sizeof(buf), format,
979 (int) (inode->i_nlink - realinode->i_nlink));
980
981 if (WARN_ON(len >= sizeof(buf)))
982 return -EIO;
983
984 return ovl_setxattr(OVL_FS(inode->i_sb), ovl_dentry_upper(dentry),
985 OVL_XATTR_NLINK, buf, len);
986}
987
988int ovl_set_nlink_upper(struct dentry *dentry)
989{
990 return ovl_set_nlink_common(dentry, ovl_dentry_upper(dentry), "U%+i");
991}
992
993int ovl_set_nlink_lower(struct dentry *dentry)
994{
995 return ovl_set_nlink_common(dentry, ovl_dentry_lower(dentry), "L%+i");
996}
997
998unsigned int ovl_get_nlink(struct ovl_fs *ofs, struct dentry *lowerdentry,
999 struct dentry *upperdentry,
1000 unsigned int fallback)
1001{
1002 int nlink_diff;
1003 int nlink;
1004 char buf[13];
1005 int err;
1006
1007 if (!lowerdentry || !upperdentry || d_inode(lowerdentry)->i_nlink == 1)
1008 return fallback;
1009
1010 err = ovl_getxattr_upper(ofs, upperdentry, OVL_XATTR_NLINK,
1011 &buf, sizeof(buf) - 1);
1012 if (err < 0)
1013 goto fail;
1014
1015 buf[err] = '\0';
1016 if ((buf[0] != 'L' && buf[0] != 'U') ||
1017 (buf[1] != '+' && buf[1] != '-'))
1018 goto fail;
1019
1020 err = kstrtoint(buf + 1, 10, &nlink_diff);
1021 if (err < 0)
1022 goto fail;
1023
1024 nlink = d_inode(buf[0] == 'L' ? lowerdentry : upperdentry)->i_nlink;
1025 nlink += nlink_diff;
1026
1027 if (nlink <= 0)
1028 goto fail;
1029
1030 return nlink;
1031
1032fail:
1033 pr_warn_ratelimited("failed to get index nlink (%pd2, err=%i)\n",
1034 upperdentry, err);
1035 return fallback;
1036}
1037
1038struct inode *ovl_new_inode(struct super_block *sb, umode_t mode, dev_t rdev)
1039{
1040 struct inode *inode;
1041
1042 inode = new_inode(sb);
1043 if (inode)
1044 ovl_fill_inode(inode, mode, rdev);
1045
1046 return inode;
1047}
1048
1049static int ovl_inode_test(struct inode *inode, void *data)
1050{
1051 return inode->i_private == data;
1052}
1053
1054static int ovl_inode_set(struct inode *inode, void *data)
1055{
1056 inode->i_private = data;
1057 return 0;
1058}
1059
1060static bool ovl_verify_inode(struct inode *inode, struct dentry *lowerdentry,
1061 struct dentry *upperdentry, bool strict)
1062{
1063 /*
1064 * For directories, @strict verify from lookup path performs consistency
1065 * checks, so NULL lower/upper in dentry must match NULL lower/upper in
1066 * inode. Non @strict verify from NFS handle decode path passes NULL for
1067 * 'unknown' lower/upper.
1068 */
1069 if (S_ISDIR(inode->i_mode) && strict) {
1070 /* Real lower dir moved to upper layer under us? */
1071 if (!lowerdentry && ovl_inode_lower(inode))
1072 return false;
1073
1074 /* Lookup of an uncovered redirect origin? */
1075 if (!upperdentry && ovl_inode_upper(inode))
1076 return false;
1077 }
1078
1079 /*
1080 * Allow non-NULL lower inode in ovl_inode even if lowerdentry is NULL.
1081 * This happens when finding a copied up overlay inode for a renamed
1082 * or hardlinked overlay dentry and lower dentry cannot be followed
1083 * by origin because lower fs does not support file handles.
1084 */
1085 if (lowerdentry && ovl_inode_lower(inode) != d_inode(lowerdentry))
1086 return false;
1087
1088 /*
1089 * Allow non-NULL __upperdentry in inode even if upperdentry is NULL.
1090 * This happens when finding a lower alias for a copied up hard link.
1091 */
1092 if (upperdentry && ovl_inode_upper(inode) != d_inode(upperdentry))
1093 return false;
1094
1095 return true;
1096}
1097
1098struct inode *ovl_lookup_inode(struct super_block *sb, struct dentry *real,
1099 bool is_upper)
1100{
1101 struct inode *inode, *key = d_inode(real);
1102
1103 inode = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
1104 if (!inode)
1105 return NULL;
1106
1107 if (!ovl_verify_inode(inode, is_upper ? NULL : real,
1108 is_upper ? real : NULL, false)) {
1109 iput(inode);
1110 return ERR_PTR(-ESTALE);
1111 }
1112
1113 return inode;
1114}
1115
1116bool ovl_lookup_trap_inode(struct super_block *sb, struct dentry *dir)
1117{
1118 struct inode *key = d_inode(dir);
1119 struct inode *trap;
1120 bool res;
1121
1122 trap = ilookup5(sb, (unsigned long) key, ovl_inode_test, key);
1123 if (!trap)
1124 return false;
1125
1126 res = IS_DEADDIR(trap) && !ovl_inode_upper(trap) &&
1127 !ovl_inode_lower(trap);
1128
1129 iput(trap);
1130 return res;
1131}
1132
1133/*
1134 * Create an inode cache entry for layer root dir, that will intentionally
1135 * fail ovl_verify_inode(), so any lookup that will find some layer root
1136 * will fail.
1137 */
1138struct inode *ovl_get_trap_inode(struct super_block *sb, struct dentry *dir)
1139{
1140 struct inode *key = d_inode(dir);
1141 struct inode *trap;
1142
1143 if (!d_is_dir(dir))
1144 return ERR_PTR(-ENOTDIR);
1145
1146 trap = iget5_locked(sb, (unsigned long) key, ovl_inode_test,
1147 ovl_inode_set, key);
1148 if (!trap)
1149 return ERR_PTR(-ENOMEM);
1150
1151 if (!(trap->i_state & I_NEW)) {
1152 /* Conflicting layer roots? */
1153 iput(trap);
1154 return ERR_PTR(-ELOOP);
1155 }
1156
1157 trap->i_mode = S_IFDIR;
1158 trap->i_flags = S_DEAD;
1159 unlock_new_inode(trap);
1160
1161 return trap;
1162}
1163
1164/*
1165 * Does overlay inode need to be hashed by lower inode?
1166 */
1167static bool ovl_hash_bylower(struct super_block *sb, struct dentry *upper,
1168 struct dentry *lower, bool index)
1169{
1170 struct ovl_fs *ofs = OVL_FS(sb);
1171
1172 /* No, if pure upper */
1173 if (!lower)
1174 return false;
1175
1176 /* Yes, if already indexed */
1177 if (index)
1178 return true;
1179
1180 /* Yes, if won't be copied up */
1181 if (!ovl_upper_mnt(ofs))
1182 return true;
1183
1184 /* No, if lower hardlink is or will be broken on copy up */
1185 if ((upper || !ovl_indexdir(sb)) &&
1186 !d_is_dir(lower) && d_inode(lower)->i_nlink > 1)
1187 return false;
1188
1189 /* No, if non-indexed upper with NFS export */
1190 if (ofs->config.nfs_export && upper)
1191 return false;
1192
1193 /* Otherwise, hash by lower inode for fsnotify */
1194 return true;
1195}
1196
1197static struct inode *ovl_iget5(struct super_block *sb, struct inode *newinode,
1198 struct inode *key)
1199{
1200 return newinode ? inode_insert5(newinode, (unsigned long) key,
1201 ovl_inode_test, ovl_inode_set, key) :
1202 iget5_locked(sb, (unsigned long) key,
1203 ovl_inode_test, ovl_inode_set, key);
1204}
1205
1206struct inode *ovl_get_inode(struct super_block *sb,
1207 struct ovl_inode_params *oip)
1208{
1209 struct ovl_fs *ofs = OVL_FS(sb);
1210 struct dentry *upperdentry = oip->upperdentry;
1211 struct ovl_path *lowerpath = ovl_lowerpath(oip->oe);
1212 struct inode *realinode = upperdentry ? d_inode(upperdentry) : NULL;
1213 struct inode *inode;
1214 struct dentry *lowerdentry = lowerpath ? lowerpath->dentry : NULL;
1215 struct path realpath = {
1216 .dentry = upperdentry ?: lowerdentry,
1217 .mnt = upperdentry ? ovl_upper_mnt(ofs) : lowerpath->layer->mnt,
1218 };
1219 bool bylower = ovl_hash_bylower(sb, upperdentry, lowerdentry,
1220 oip->index);
1221 int fsid = bylower ? lowerpath->layer->fsid : 0;
1222 bool is_dir;
1223 unsigned long ino = 0;
1224 int err = oip->newinode ? -EEXIST : -ENOMEM;
1225
1226 if (!realinode)
1227 realinode = d_inode(lowerdentry);
1228
1229 /*
1230 * Copy up origin (lower) may exist for non-indexed upper, but we must
1231 * not use lower as hash key if this is a broken hardlink.
1232 */
1233 is_dir = S_ISDIR(realinode->i_mode);
1234 if (upperdentry || bylower) {
1235 struct inode *key = d_inode(bylower ? lowerdentry :
1236 upperdentry);
1237 unsigned int nlink = is_dir ? 1 : realinode->i_nlink;
1238
1239 inode = ovl_iget5(sb, oip->newinode, key);
1240 if (!inode)
1241 goto out_err;
1242 if (!(inode->i_state & I_NEW)) {
1243 /*
1244 * Verify that the underlying files stored in the inode
1245 * match those in the dentry.
1246 */
1247 if (!ovl_verify_inode(inode, lowerdentry, upperdentry,
1248 true)) {
1249 iput(inode);
1250 err = -ESTALE;
1251 goto out_err;
1252 }
1253
1254 dput(upperdentry);
1255 ovl_free_entry(oip->oe);
1256 kfree(oip->redirect);
1257 kfree(oip->lowerdata_redirect);
1258 goto out;
1259 }
1260
1261 /* Recalculate nlink for non-dir due to indexing */
1262 if (!is_dir)
1263 nlink = ovl_get_nlink(ofs, lowerdentry, upperdentry,
1264 nlink);
1265 set_nlink(inode, nlink);
1266 ino = key->i_ino;
1267 } else {
1268 /* Lower hardlink that will be broken on copy up */
1269 inode = new_inode(sb);
1270 if (!inode) {
1271 err = -ENOMEM;
1272 goto out_err;
1273 }
1274 ino = realinode->i_ino;
1275 fsid = lowerpath->layer->fsid;
1276 }
1277 ovl_fill_inode(inode, realinode->i_mode, realinode->i_rdev);
1278 ovl_inode_init(inode, oip, ino, fsid);
1279
1280 if (upperdentry && ovl_is_impuredir(sb, upperdentry))
1281 ovl_set_flag(OVL_IMPURE, inode);
1282
1283 if (oip->index)
1284 ovl_set_flag(OVL_INDEX, inode);
1285
1286 if (bylower)
1287 ovl_set_flag(OVL_CONST_INO, inode);
1288
1289 /* Check for non-merge dir that may have whiteouts */
1290 if (is_dir) {
1291 if (((upperdentry && lowerdentry) || ovl_numlower(oip->oe) > 1) ||
1292 ovl_path_check_origin_xattr(ofs, &realpath)) {
1293 ovl_set_flag(OVL_WHITEOUTS, inode);
1294 }
1295 }
1296
1297 /* Check for immutable/append-only inode flags in xattr */
1298 if (upperdentry)
1299 ovl_check_protattr(inode, upperdentry);
1300
1301 if (inode->i_state & I_NEW)
1302 unlock_new_inode(inode);
1303out:
1304 return inode;
1305
1306out_err:
1307 pr_warn_ratelimited("failed to get inode (%i)\n", err);
1308 inode = ERR_PTR(err);
1309 goto out;
1310}