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/fileattr.h>
12#include <linux/splice.h>
13#include <linux/xattr.h>
14#include <linux/security.h>
15#include <linux/uaccess.h>
16#include <linux/sched/signal.h>
17#include <linux/cred.h>
18#include <linux/namei.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
25static 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27 pr_warn("\"check_copy_up\" module option is obsolete\n");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
31static int ovl_ccup_get(char *buf, const struct kernel_param *param)
32{
33 return sprintf(buf, fmt: "N\n");
34}
35
36module_param_call(check_copy_up, ovl_ccup_set, ovl_ccup_get, NULL, 0644);
37MODULE_PARM_DESC(check_copy_up, "Obsolete; does nothing");
38
39static 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
46static int ovl_copy_acl(struct ovl_fs *ofs, const struct path *path,
47 struct dentry *dentry, const char *acl_name)
48{
49 int err;
50 struct posix_acl *clone, *real_acl = NULL;
51
52 real_acl = ovl_get_acl_path(path, acl_name, noperm: false);
53 if (!real_acl)
54 return 0;
55
56 if (IS_ERR(ptr: real_acl)) {
57 err = PTR_ERR(ptr: real_acl);
58 if (err == -ENODATA || err == -EOPNOTSUPP)
59 return 0;
60 return err;
61 }
62
63 clone = posix_acl_clone(acl: real_acl, GFP_KERNEL);
64 posix_acl_release(acl: real_acl); /* release original acl */
65 if (!clone)
66 return -ENOMEM;
67
68 err = ovl_do_set_acl(ofs, dentry, acl_name, acl: clone);
69
70 /* release cloned acl */
71 posix_acl_release(acl: clone);
72 return err;
73}
74
75int ovl_copy_xattr(struct super_block *sb, const struct path *oldpath, struct dentry *new)
76{
77 struct dentry *old = oldpath->dentry;
78 ssize_t list_size, size, value_size = 0;
79 char *buf, *name, *value = NULL;
80 int error = 0;
81 size_t slen;
82
83 if (!old->d_inode->i_op->listxattr || !new->d_inode->i_op->listxattr)
84 return 0;
85
86 list_size = vfs_listxattr(d: old, NULL, size: 0);
87 if (list_size <= 0) {
88 if (list_size == -EOPNOTSUPP)
89 return 0;
90 return list_size;
91 }
92
93 buf = kvzalloc(list_size, GFP_KERNEL);
94 if (!buf)
95 return -ENOMEM;
96
97 list_size = vfs_listxattr(d: old, list: buf, size: list_size);
98 if (list_size <= 0) {
99 error = list_size;
100 goto out;
101 }
102
103 for (name = buf; list_size; name += slen) {
104 slen = strnlen(p: name, maxlen: list_size) + 1;
105
106 /* underlying fs providing us with an broken xattr list? */
107 if (WARN_ON(slen > list_size)) {
108 error = -EIO;
109 break;
110 }
111 list_size -= slen;
112
113 if (ovl_is_private_xattr(sb, name))
114 continue;
115
116 error = security_inode_copy_up_xattr(src: old, name);
117 if (error == -ECANCELED) {
118 error = 0;
119 continue; /* Discard */
120 }
121 if (error < 0 && error != -EOPNOTSUPP)
122 break;
123
124 if (is_posix_acl_xattr(name)) {
125 error = ovl_copy_acl(ofs: OVL_FS(sb), path: oldpath, dentry: new, acl_name: name);
126 if (!error)
127 continue;
128 /* POSIX ACLs must be copied. */
129 break;
130 }
131
132retry:
133 size = ovl_do_getxattr(path: oldpath, name, value, size: value_size);
134 if (size == -ERANGE)
135 size = ovl_do_getxattr(path: oldpath, name, NULL, size: 0);
136
137 if (size < 0) {
138 error = size;
139 break;
140 }
141
142 if (size > value_size) {
143 void *new;
144
145 new = kvmalloc(size, GFP_KERNEL);
146 if (!new) {
147 error = -ENOMEM;
148 break;
149 }
150 kvfree(addr: value);
151 value = new;
152 value_size = size;
153 goto retry;
154 }
155
156 error = ovl_do_setxattr(ofs: OVL_FS(sb), dentry: new, name, value, size, flags: 0);
157 if (error) {
158 if (error != -EOPNOTSUPP || ovl_must_copy_xattr(name))
159 break;
160
161 /* Ignore failure to copy unknown xattrs */
162 error = 0;
163 }
164 }
165 kvfree(addr: value);
166out:
167 kvfree(addr: buf);
168 return error;
169}
170
171static int ovl_copy_fileattr(struct inode *inode, const struct path *old,
172 const struct path *new)
173{
174 struct file_kattr oldfa = { .flags_valid = true };
175 struct file_kattr newfa = { .flags_valid = true };
176 int err;
177
178 err = ovl_real_fileattr_get(realpath: old, fa: &oldfa);
179 if (err) {
180 /* Ntfs-3g returns -EINVAL for "no fileattr support" */
181 if (err == -ENOTTY || err == -EINVAL)
182 return 0;
183 pr_warn("failed to retrieve lower fileattr (%pd2, err=%i)\n",
184 old->dentry, err);
185 return err;
186 }
187
188 /*
189 * We cannot set immutable and append-only flags on upper inode,
190 * because we would not be able to link upper inode to upper dir
191 * not set overlay private xattr on upper inode.
192 * Store these flags in overlay.protattr xattr instead.
193 */
194 if (oldfa.flags & OVL_PROT_FS_FLAGS_MASK) {
195 err = ovl_set_protattr(inode, upper: new->dentry, fa: &oldfa);
196 if (err == -EPERM)
197 pr_warn_once("copying fileattr: no xattr on upper\n");
198 else if (err)
199 return err;
200 }
201
202 /* Don't bother copying flags if none are set */
203 if (!(oldfa.flags & OVL_COPY_FS_FLAGS_MASK))
204 return 0;
205
206 err = ovl_real_fileattr_get(realpath: new, fa: &newfa);
207 if (err) {
208 /*
209 * Returning an error if upper doesn't support fileattr will
210 * result in a regression, so revert to the old behavior.
211 */
212 if (err == -ENOTTY || err == -EINVAL) {
213 pr_warn_once("copying fileattr: no support on upper\n");
214 return 0;
215 }
216 pr_warn("failed to retrieve upper fileattr (%pd2, err=%i)\n",
217 new->dentry, err);
218 return err;
219 }
220
221 BUILD_BUG_ON(OVL_COPY_FS_FLAGS_MASK & ~FS_COMMON_FL);
222 newfa.flags &= ~OVL_COPY_FS_FLAGS_MASK;
223 newfa.flags |= (oldfa.flags & OVL_COPY_FS_FLAGS_MASK);
224
225 BUILD_BUG_ON(OVL_COPY_FSX_FLAGS_MASK & ~FS_XFLAG_COMMON);
226 newfa.fsx_xflags &= ~OVL_COPY_FSX_FLAGS_MASK;
227 newfa.fsx_xflags |= (oldfa.fsx_xflags & OVL_COPY_FSX_FLAGS_MASK);
228
229 return ovl_real_fileattr_set(realpath: new, fa: &newfa);
230}
231
232static int ovl_verify_area(loff_t pos, loff_t pos2, loff_t len, loff_t totlen)
233{
234 loff_t tmp;
235
236 if (pos != pos2)
237 return -EIO;
238 if (pos < 0 || len < 0 || totlen < 0)
239 return -EIO;
240 if (check_add_overflow(pos, len, &tmp))
241 return -EIO;
242 return 0;
243}
244
245static int ovl_sync_file(const struct path *path)
246{
247 struct file *new_file;
248 int err;
249
250 new_file = ovl_path_open(path, O_LARGEFILE | O_RDONLY);
251 if (IS_ERR(ptr: new_file))
252 return PTR_ERR(ptr: new_file);
253
254 err = vfs_fsync(file: new_file, datasync: 0);
255 fput(new_file);
256
257 return err;
258}
259
260static int ovl_copy_up_file(struct ovl_fs *ofs, struct dentry *dentry,
261 struct file *new_file, loff_t len,
262 bool datasync)
263{
264 struct path datapath;
265 struct file *old_file;
266 loff_t old_pos = 0;
267 loff_t new_pos = 0;
268 loff_t cloned;
269 loff_t data_pos = -1;
270 loff_t hole_len;
271 bool skip_hole = false;
272 int error = 0;
273
274 ovl_path_lowerdata(dentry, path: &datapath);
275 if (WARN_ON_ONCE(datapath.dentry == NULL) ||
276 WARN_ON_ONCE(len < 0))
277 return -EIO;
278
279 old_file = ovl_path_open(path: &datapath, O_LARGEFILE | O_RDONLY);
280 if (IS_ERR(ptr: old_file))
281 return PTR_ERR(ptr: old_file);
282
283 /* Try to use clone_file_range to clone up within the same fs */
284 cloned = vfs_clone_file_range(file_in: old_file, pos_in: 0, file_out: new_file, pos_out: 0, len, remap_flags: 0);
285 if (cloned == len)
286 goto out_fput;
287
288 /* Couldn't clone, so now we try to copy the data */
289 error = rw_verify_area(READ, old_file, &old_pos, len);
290 if (!error)
291 error = rw_verify_area(WRITE, new_file, &new_pos, len);
292 if (error)
293 goto out_fput;
294
295 /* Check if lower fs supports seek operation */
296 if (old_file->f_mode & FMODE_LSEEK)
297 skip_hole = true;
298
299 while (len) {
300 size_t this_len = OVL_COPY_UP_CHUNK_SIZE;
301 ssize_t bytes;
302
303 if (len < this_len)
304 this_len = len;
305
306 if (signal_pending_state(TASK_KILLABLE, current)) {
307 error = -EINTR;
308 break;
309 }
310
311 /*
312 * Fill zero for hole will cost unnecessary disk space
313 * and meanwhile slow down the copy-up speed, so we do
314 * an optimization for hole during copy-up, it relies
315 * on SEEK_DATA implementation in lower fs so if lower
316 * fs does not support it, copy-up will behave as before.
317 *
318 * Detail logic of hole detection as below:
319 * When we detect next data position is larger than current
320 * position we will skip that hole, otherwise we copy
321 * data in the size of OVL_COPY_UP_CHUNK_SIZE. Actually,
322 * it may not recognize all kind of holes and sometimes
323 * only skips partial of hole area. However, it will be
324 * enough for most of the use cases.
325 *
326 * We do not hold upper sb_writers throughout the loop to avert
327 * lockdep warning with llseek of lower file in nested overlay:
328 * - upper sb_writers
329 * -- lower ovl_inode_lock (ovl_llseek)
330 */
331 if (skip_hole && data_pos < old_pos) {
332 data_pos = vfs_llseek(file: old_file, offset: old_pos, SEEK_DATA);
333 if (data_pos > old_pos) {
334 hole_len = data_pos - old_pos;
335 len -= hole_len;
336 old_pos = new_pos = data_pos;
337 continue;
338 } else if (data_pos == -ENXIO) {
339 break;
340 } else if (data_pos < 0) {
341 skip_hole = false;
342 }
343 }
344
345 error = ovl_verify_area(pos: old_pos, pos2: new_pos, len: this_len, totlen: len);
346 if (error)
347 break;
348
349 bytes = do_splice_direct(in: old_file, ppos: &old_pos,
350 out: new_file, opos: &new_pos,
351 len: this_len, SPLICE_F_MOVE);
352 if (bytes <= 0) {
353 error = bytes;
354 break;
355 }
356 WARN_ON(old_pos != new_pos);
357
358 len -= bytes;
359 }
360 /* call fsync once, either now or later along with metadata */
361 if (!error && ovl_should_sync(ofs) && datasync)
362 error = vfs_fsync(file: new_file, datasync: 0);
363out_fput:
364 fput(old_file);
365 return error;
366}
367
368static int ovl_set_size(struct ovl_fs *ofs,
369 struct dentry *upperdentry, struct kstat *stat)
370{
371 struct iattr attr = {
372 .ia_valid = ATTR_SIZE,
373 .ia_size = stat->size,
374 };
375
376 return ovl_do_notify_change(ofs, upperdentry, attr: &attr);
377}
378
379static int ovl_set_timestamps(struct ovl_fs *ofs, struct dentry *upperdentry,
380 struct kstat *stat)
381{
382 struct iattr attr = {
383 .ia_valid =
384 ATTR_ATIME | ATTR_MTIME | ATTR_ATIME_SET | ATTR_MTIME_SET | ATTR_CTIME,
385 .ia_atime = stat->atime,
386 .ia_mtime = stat->mtime,
387 };
388
389 return ovl_do_notify_change(ofs, upperdentry, attr: &attr);
390}
391
392int ovl_set_attr(struct ovl_fs *ofs, struct dentry *upperdentry,
393 struct kstat *stat)
394{
395 int err = 0;
396
397 if (!S_ISLNK(stat->mode)) {
398 struct iattr attr = {
399 .ia_valid = ATTR_MODE,
400 .ia_mode = stat->mode,
401 };
402 err = ovl_do_notify_change(ofs, upperdentry, attr: &attr);
403 }
404 if (!err) {
405 struct iattr attr = {
406 .ia_valid = ATTR_UID | ATTR_GID,
407 .ia_vfsuid = VFSUIDT_INIT(stat->uid),
408 .ia_vfsgid = VFSGIDT_INIT(stat->gid),
409 };
410 err = ovl_do_notify_change(ofs, upperdentry, attr: &attr);
411 }
412 if (!err)
413 ovl_set_timestamps(ofs, upperdentry, stat);
414
415 return err;
416}
417
418struct ovl_fh *ovl_encode_real_fh(struct ovl_fs *ofs, struct inode *realinode,
419 bool is_upper)
420{
421 struct ovl_fh *fh;
422 int fh_type, dwords;
423 int buflen = MAX_HANDLE_SZ;
424 uuid_t *uuid = &realinode->i_sb->s_uuid;
425 int err;
426
427 /* Make sure the real fid stays 32bit aligned */
428 BUILD_BUG_ON(OVL_FH_FID_OFFSET % 4);
429 BUILD_BUG_ON(MAX_HANDLE_SZ + OVL_FH_FID_OFFSET > 255);
430
431 fh = kzalloc(buflen + OVL_FH_FID_OFFSET, GFP_KERNEL);
432 if (!fh)
433 return ERR_PTR(error: -ENOMEM);
434
435 /*
436 * We encode a non-connectable file handle for non-dir, because we
437 * only need to find the lower inode number and we don't want to pay
438 * the price or reconnecting the dentry.
439 */
440 dwords = buflen >> 2;
441 fh_type = exportfs_encode_inode_fh(inode: realinode, fid: (void *)fh->fb.fid,
442 max_len: &dwords, NULL, flags: 0);
443 buflen = (dwords << 2);
444
445 err = -EIO;
446 if (fh_type < 0 || fh_type == FILEID_INVALID ||
447 WARN_ON(buflen > MAX_HANDLE_SZ))
448 goto out_err;
449
450 fh->fb.version = OVL_FH_VERSION;
451 fh->fb.magic = OVL_FH_MAGIC;
452 fh->fb.type = fh_type;
453 fh->fb.flags = OVL_FH_FLAG_CPU_ENDIAN;
454 /*
455 * When we will want to decode an overlay dentry from this handle
456 * and all layers are on the same fs, if we get a disconncted real
457 * dentry when we decode fid, the only way to tell if we should assign
458 * it to upperdentry or to lowerstack is by checking this flag.
459 */
460 if (is_upper)
461 fh->fb.flags |= OVL_FH_FLAG_PATH_UPPER;
462 fh->fb.len = sizeof(fh->fb) + buflen;
463 if (ovl_origin_uuid(ofs))
464 fh->fb.uuid = *uuid;
465
466 return fh;
467
468out_err:
469 kfree(objp: fh);
470 return ERR_PTR(error: err);
471}
472
473struct ovl_fh *ovl_get_origin_fh(struct ovl_fs *ofs, struct dentry *origin)
474{
475 /*
476 * When lower layer doesn't support export operations store a 'null' fh,
477 * so we can use the overlay.origin xattr to distignuish between a copy
478 * up and a pure upper inode.
479 */
480 if (!ovl_can_decode_fh(sb: origin->d_sb))
481 return NULL;
482
483 return ovl_encode_real_fh(ofs, realinode: d_inode(dentry: origin), is_upper: false);
484}
485
486int ovl_set_origin_fh(struct ovl_fs *ofs, const struct ovl_fh *fh,
487 struct dentry *upper)
488{
489 int err;
490
491 /*
492 * Do not fail when upper doesn't support xattrs.
493 */
494 err = ovl_check_setxattr(ofs, upperdentry: upper, ox: OVL_XATTR_ORIGIN, value: fh->buf,
495 size: fh ? fh->fb.len : 0, xerr: 0);
496
497 /* Ignore -EPERM from setting "user.*" on symlink/special */
498 return err == -EPERM ? 0 : err;
499}
500
501/* Store file handle of @upper dir in @index dir entry */
502static int ovl_set_upper_fh(struct ovl_fs *ofs, struct dentry *upper,
503 struct dentry *index)
504{
505 const struct ovl_fh *fh;
506 int err;
507
508 fh = ovl_encode_real_fh(ofs, realinode: d_inode(dentry: upper), is_upper: true);
509 if (IS_ERR(ptr: fh))
510 return PTR_ERR(ptr: fh);
511
512 err = ovl_setxattr(ofs, dentry: index, ox: OVL_XATTR_UPPER, value: fh->buf, size: fh->fb.len);
513
514 kfree(objp: fh);
515 return err;
516}
517
518/*
519 * Create and install index entry.
520 */
521static int ovl_create_index(struct dentry *dentry, const struct ovl_fh *fh,
522 struct dentry *upper)
523{
524 struct ovl_fs *ofs = OVL_FS(sb: dentry->d_sb);
525 struct dentry *indexdir = ovl_indexdir(sb: dentry->d_sb);
526 struct dentry *temp = NULL;
527 struct renamedata rd = {};
528 struct qstr name = { };
529 int err;
530
531 /*
532 * For now this is only used for creating index entry for directories,
533 * because non-dir are copied up directly to index and then hardlinked
534 * to upper dir.
535 *
536 * TODO: implement create index for non-dir, so we can call it when
537 * encoding file handle for non-dir in case index does not exist.
538 */
539 if (WARN_ON(!d_is_dir(dentry)))
540 return -EIO;
541
542 /* Directory not expected to be indexed before copy up */
543 if (WARN_ON(ovl_test_flag(OVL_INDEX, d_inode(dentry))))
544 return -EIO;
545
546 err = ovl_get_index_name_fh(fh, name: &name);
547 if (err)
548 return err;
549
550 temp = ovl_create_temp(ofs, workdir: indexdir, OVL_CATTR(S_IFDIR | 0));
551 err = PTR_ERR(ptr: temp);
552 if (IS_ERR(ptr: temp))
553 goto free_name;
554
555 err = ovl_set_upper_fh(ofs, upper, index: temp);
556 if (err)
557 goto out;
558
559 rd.mnt_idmap = ovl_upper_mnt_idmap(ofs);
560 rd.old_parent = indexdir;
561 rd.new_parent = indexdir;
562 err = start_renaming_dentry(rd: &rd, lookup_flags: 0, old_dentry: temp, new_last: &name);
563 if (err)
564 goto out;
565
566 err = ovl_do_rename_rd(rd: &rd);
567 end_renaming(rd: &rd);
568out:
569 if (err)
570 ovl_cleanup(ofs, workdir: indexdir, dentry: temp);
571 dput(temp);
572free_name:
573 kfree(objp: name.name);
574 return err;
575}
576
577struct ovl_copy_up_ctx {
578 struct dentry *parent;
579 struct dentry *dentry;
580 struct path lowerpath;
581 struct kstat stat;
582 struct kstat pstat;
583 const char *link;
584 struct dentry *destdir;
585 struct qstr destname;
586 struct dentry *workdir;
587 const struct ovl_fh *origin_fh;
588 bool origin;
589 bool indexed;
590 bool metacopy;
591 bool metacopy_digest;
592 bool metadata_fsync;
593};
594
595static int ovl_link_up(struct ovl_copy_up_ctx *c)
596{
597 int err;
598 struct dentry *upper;
599 struct dentry *upperdir = ovl_dentry_upper(dentry: c->parent);
600 struct ovl_fs *ofs = OVL_FS(sb: c->dentry->d_sb);
601 struct inode *udir = d_inode(dentry: upperdir);
602
603 ovl_start_write(dentry: c->dentry);
604
605 /* Mark parent "impure" because it may now contain non-pure upper */
606 err = ovl_set_impure(dentry: c->parent, upperdentry: upperdir);
607 if (err)
608 goto out;
609
610 err = ovl_set_nlink_lower(dentry: c->dentry);
611 if (err)
612 goto out;
613
614 upper = ovl_start_creating_upper(ofs, parent: upperdir,
615 name: &QSTR_LEN(c->dentry->d_name.name,
616 c->dentry->d_name.len));
617 err = PTR_ERR(ptr: upper);
618 if (!IS_ERR(ptr: upper)) {
619 err = ovl_do_link(ofs, old_dentry: ovl_dentry_upper(dentry: c->dentry), dir: udir, new_dentry: upper);
620
621 if (!err) {
622 /* Restore timestamps on parent (best effort) */
623 ovl_set_timestamps(ofs, upperdentry: upperdir, stat: &c->pstat);
624 ovl_dentry_set_upper_alias(dentry: c->dentry);
625 ovl_dentry_update_reval(dentry: c->dentry, realdentry: upper);
626 }
627 end_creating(child: upper);
628 }
629 if (err)
630 goto out;
631
632 err = ovl_set_nlink_upper(dentry: c->dentry);
633
634out:
635 ovl_end_write(dentry: c->dentry);
636 return err;
637}
638
639static int ovl_copy_up_data(struct ovl_copy_up_ctx *c, const struct path *temp)
640{
641 struct ovl_fs *ofs = OVL_FS(sb: c->dentry->d_sb);
642 struct file *new_file;
643 int err;
644
645 if (!S_ISREG(c->stat.mode) || c->metacopy || !c->stat.size)
646 return 0;
647
648 new_file = ovl_path_open(path: temp, O_LARGEFILE | O_WRONLY);
649 if (IS_ERR(ptr: new_file))
650 return PTR_ERR(ptr: new_file);
651
652 err = ovl_copy_up_file(ofs, dentry: c->dentry, new_file, len: c->stat.size,
653 datasync: !c->metadata_fsync);
654 fput(new_file);
655
656 return err;
657}
658
659static int ovl_copy_up_metadata(struct ovl_copy_up_ctx *c, struct dentry *temp)
660{
661 struct ovl_fs *ofs = OVL_FS(sb: c->dentry->d_sb);
662 struct inode *inode = d_inode(dentry: c->dentry);
663 struct path upperpath = { .mnt = ovl_upper_mnt(ofs), .dentry = temp };
664 int err;
665
666 err = ovl_copy_xattr(sb: c->dentry->d_sb, oldpath: &c->lowerpath, new: temp);
667 if (err)
668 return err;
669
670 if (inode->i_flags & OVL_FATTR_I_FLAGS_MASK &&
671 (S_ISREG(c->stat.mode) || S_ISDIR(c->stat.mode))) {
672 /*
673 * Copy the fileattr inode flags that are the source of already
674 * copied i_flags
675 */
676 err = ovl_copy_fileattr(inode, old: &c->lowerpath, new: &upperpath);
677 if (err)
678 return err;
679 }
680
681 /*
682 * Store identifier of lower inode in upper inode xattr to
683 * allow lookup of the copy up origin inode.
684 *
685 * Don't set origin when we are breaking the association with a lower
686 * hard link.
687 */
688 if (c->origin) {
689 err = ovl_set_origin_fh(ofs, fh: c->origin_fh, upper: temp);
690 if (err)
691 return err;
692 }
693
694 if (c->metacopy) {
695 struct path lowerdatapath;
696 struct ovl_metacopy metacopy_data = OVL_METACOPY_INIT;
697
698 ovl_path_lowerdata(dentry: c->dentry, path: &lowerdatapath);
699 if (WARN_ON_ONCE(lowerdatapath.dentry == NULL))
700 return -EIO;
701 err = ovl_get_verity_digest(ofs, src: &lowerdatapath, metacopy: &metacopy_data);
702 if (err)
703 return err;
704
705 if (metacopy_data.digest_algo)
706 c->metacopy_digest = true;
707
708 err = ovl_set_metacopy_xattr(ofs, d: temp, metacopy: &metacopy_data);
709 if (err)
710 return err;
711 }
712
713 inode_lock(inode: temp->d_inode);
714 if (S_ISREG(c->stat.mode))
715 err = ovl_set_size(ofs, upperdentry: temp, stat: &c->stat);
716 if (!err)
717 err = ovl_set_attr(ofs, upperdentry: temp, stat: &c->stat);
718 inode_unlock(inode: temp->d_inode);
719
720 /* fsync metadata before moving it into upper dir */
721 if (!err && ovl_should_sync(ofs) && c->metadata_fsync)
722 err = ovl_sync_file(path: &upperpath);
723
724 return err;
725}
726
727static const struct cred *ovl_prepare_copy_up_creds(struct dentry *dentry)
728{
729 struct cred *copy_up_cred = NULL;
730 int err;
731
732 err = security_inode_copy_up(src: dentry, new: &copy_up_cred);
733 if (err < 0)
734 return ERR_PTR(error: err);
735
736 if (!copy_up_cred)
737 return NULL;
738
739 return override_creds(override_cred: copy_up_cred);
740}
741
742static void ovl_revert_copy_up_creds(const struct cred *orig_cred)
743{
744 const struct cred *copy_up_cred;
745
746 copy_up_cred = revert_creds(revert_cred: orig_cred);
747 put_cred(cred: copy_up_cred);
748}
749
750DEFINE_CLASS(copy_up_creds, const struct cred *,
751 if (!IS_ERR_OR_NULL(_T)) ovl_revert_copy_up_creds(_T),
752 ovl_prepare_copy_up_creds(dentry), struct dentry *dentry)
753
754/*
755 * Copyup using workdir to prepare temp file. Used when copying up directories,
756 * special files or when upper fs doesn't support O_TMPFILE.
757 */
758static int ovl_copy_up_workdir(struct ovl_copy_up_ctx *c)
759{
760 struct ovl_fs *ofs = OVL_FS(sb: c->dentry->d_sb);
761 struct inode *inode;
762 struct path path = { .mnt = ovl_upper_mnt(ofs) };
763 struct renamedata rd = {};
764 struct dentry *temp;
765 int err;
766 struct ovl_cattr cattr = {
767 /* Can't properly set mode on creation because of the umask */
768 .mode = c->stat.mode & S_IFMT,
769 .rdev = c->stat.rdev,
770 .link = c->link
771 };
772
773 scoped_class(copy_up_creds, copy_up_creds, c->dentry) {
774 if (IS_ERR(ptr: copy_up_creds))
775 return PTR_ERR(ptr: copy_up_creds);
776
777 ovl_start_write(dentry: c->dentry);
778 temp = ovl_create_temp(ofs, workdir: c->workdir, attr: &cattr);
779 ovl_end_write(dentry: c->dentry);
780 }
781
782 if (IS_ERR(ptr: temp))
783 return PTR_ERR(ptr: temp);
784
785 /*
786 * Copy up data first and then xattrs. Writing data after
787 * xattrs will remove security.capability xattr automatically.
788 */
789 path.dentry = temp;
790 err = ovl_copy_up_data(c, temp: &path);
791 ovl_start_write(dentry: c->dentry);
792 if (err)
793 goto cleanup_unlocked;
794
795 if (S_ISDIR(c->stat.mode) && c->indexed) {
796 err = ovl_create_index(dentry: c->dentry, fh: c->origin_fh, upper: temp);
797 if (err)
798 goto cleanup_unlocked;
799 }
800
801 /*
802 * We cannot hold lock_rename() throughout this helper, because of
803 * lock ordering with sb_writers, which shouldn't be held when calling
804 * ovl_copy_up_data(), so lock workdir and destdir and make sure that
805 * temp wasn't moved before copy up completion or cleanup.
806 */
807 rd.mnt_idmap = ovl_upper_mnt_idmap(ofs);
808 rd.old_parent = c->workdir;
809 rd.new_parent = c->destdir;
810 rd.flags = 0;
811 err = start_renaming_dentry(rd: &rd, lookup_flags: 0, old_dentry: temp,
812 new_last: &QSTR_LEN(c->destname.name, c->destname.len));
813 if (err) {
814 /* temp or workdir moved underneath us? map to -EIO */
815 err = -EIO;
816 }
817 if (err)
818 goto cleanup_unlocked;
819
820 err = ovl_copy_up_metadata(c, temp);
821 if (!err)
822 err = ovl_do_rename_rd(rd: &rd);
823 end_renaming(rd: &rd);
824
825 if (err)
826 goto cleanup_unlocked;
827
828 inode = d_inode(dentry: c->dentry);
829 if (c->metacopy_digest)
830 ovl_set_flag(flag: OVL_HAS_DIGEST, inode);
831 else
832 ovl_clear_flag(flag: OVL_HAS_DIGEST, inode);
833 ovl_clear_flag(flag: OVL_VERIFIED_DIGEST, inode);
834
835 if (!c->metacopy)
836 ovl_set_upperdata(inode);
837 ovl_inode_update(inode, upperdentry: temp);
838 if (S_ISDIR(inode->i_mode))
839 ovl_set_flag(flag: OVL_WHITEOUTS, inode);
840out:
841 ovl_end_write(dentry: c->dentry);
842
843 return err;
844
845cleanup_unlocked:
846 ovl_cleanup(ofs, workdir: c->workdir, dentry: temp);
847 dput(temp);
848 goto out;
849}
850
851/* Copyup using O_TMPFILE which does not require cross dir locking */
852static int ovl_copy_up_tmpfile(struct ovl_copy_up_ctx *c)
853{
854 struct ovl_fs *ofs = OVL_FS(sb: c->dentry->d_sb);
855 struct inode *udir = d_inode(dentry: c->destdir);
856 struct dentry *temp, *upper;
857 struct file *tmpfile;
858 int err;
859
860 scoped_class(copy_up_creds, copy_up_creds, c->dentry) {
861 if (IS_ERR(ptr: copy_up_creds))
862 return PTR_ERR(ptr: copy_up_creds);
863
864 ovl_start_write(dentry: c->dentry);
865 tmpfile = ovl_do_tmpfile(ofs, dentry: c->workdir, mode: c->stat.mode);
866 ovl_end_write(dentry: c->dentry);
867 }
868
869 if (IS_ERR(ptr: tmpfile))
870 return PTR_ERR(ptr: tmpfile);
871
872 temp = tmpfile->f_path.dentry;
873 if (!c->metacopy && c->stat.size) {
874 err = ovl_copy_up_file(ofs, dentry: c->dentry, new_file: tmpfile, len: c->stat.size,
875 datasync: !c->metadata_fsync);
876 if (err)
877 goto out_fput;
878 }
879
880 ovl_start_write(dentry: c->dentry);
881
882 err = ovl_copy_up_metadata(c, temp);
883 if (err)
884 goto out;
885
886 upper = ovl_start_creating_upper(ofs, parent: c->destdir,
887 name: &QSTR_LEN(c->destname.name,
888 c->destname.len));
889 err = PTR_ERR(ptr: upper);
890 if (!IS_ERR(ptr: upper)) {
891 err = ovl_do_link(ofs, old_dentry: temp, dir: udir, new_dentry: upper);
892 end_creating(child: upper);
893 }
894
895 if (err)
896 goto out;
897
898 if (c->metacopy_digest)
899 ovl_set_flag(flag: OVL_HAS_DIGEST, inode: d_inode(dentry: c->dentry));
900 else
901 ovl_clear_flag(flag: OVL_HAS_DIGEST, inode: d_inode(dentry: c->dentry));
902 ovl_clear_flag(flag: OVL_VERIFIED_DIGEST, inode: d_inode(dentry: c->dentry));
903
904 if (!c->metacopy)
905 ovl_set_upperdata(inode: d_inode(dentry: c->dentry));
906 ovl_inode_update(inode: d_inode(dentry: c->dentry), upperdentry: dget(dentry: temp));
907
908out:
909 ovl_end_write(dentry: c->dentry);
910out_fput:
911 fput(tmpfile);
912 return err;
913}
914
915/*
916 * Copy up a single dentry
917 *
918 * All renames start with copy up of source if necessary. The actual
919 * rename will only proceed once the copy up was successful. Copy up uses
920 * upper parent i_mutex for exclusion. Since rename can change d_parent it
921 * is possible that the copy up will lock the old parent. At that point
922 * the file will have already been copied up anyway.
923 */
924static int ovl_do_copy_up(struct ovl_copy_up_ctx *c)
925{
926 int err;
927 struct ovl_fs *ofs = OVL_FS(sb: c->dentry->d_sb);
928 struct dentry *origin = c->lowerpath.dentry;
929 struct ovl_fh *fh = NULL;
930 bool to_index = false;
931
932 /*
933 * Indexed non-dir is copied up directly to the index entry and then
934 * hardlinked to upper dir. Indexed dir is copied up to indexdir,
935 * then index entry is created and then copied up dir installed.
936 * Copying dir up to indexdir instead of workdir simplifies locking.
937 */
938 if (ovl_need_index(dentry: c->dentry)) {
939 c->indexed = true;
940 if (S_ISDIR(c->stat.mode))
941 c->workdir = ovl_indexdir(sb: c->dentry->d_sb);
942 else
943 to_index = true;
944 }
945
946 if (S_ISDIR(c->stat.mode) || c->stat.nlink == 1 || to_index) {
947 fh = ovl_get_origin_fh(ofs, origin);
948 if (IS_ERR(ptr: fh))
949 return PTR_ERR(ptr: fh);
950
951 /* origin_fh may be NULL */
952 c->origin_fh = fh;
953 c->origin = true;
954 }
955
956 if (to_index) {
957 c->destdir = ovl_indexdir(sb: c->dentry->d_sb);
958 err = ovl_get_index_name(ofs, origin, name: &c->destname);
959 if (err)
960 goto out_free_fh;
961 } else if (WARN_ON(!c->parent)) {
962 /* Disconnected dentry must be copied up to index dir */
963 err = -EIO;
964 goto out_free_fh;
965 } else {
966 /*
967 * c->dentry->d_name is stabilzed by ovl_copy_up_start(),
968 * because if we got here, it means that c->dentry has no upper
969 * alias and changing ->d_name means going through ovl_rename()
970 * that will call ovl_copy_up() on source and target dentry.
971 */
972 c->destname = c->dentry->d_name;
973 /*
974 * Mark parent "impure" because it may now contain non-pure
975 * upper
976 */
977 ovl_start_write(dentry: c->dentry);
978 err = ovl_set_impure(dentry: c->parent, upperdentry: c->destdir);
979 ovl_end_write(dentry: c->dentry);
980 if (err)
981 goto out_free_fh;
982 }
983
984 /* Should we copyup with O_TMPFILE or with workdir? */
985 if (S_ISREG(c->stat.mode) && ofs->tmpfile)
986 err = ovl_copy_up_tmpfile(c);
987 else
988 err = ovl_copy_up_workdir(c);
989 if (err)
990 goto out;
991
992 if (c->indexed)
993 ovl_set_flag(flag: OVL_INDEX, inode: d_inode(dentry: c->dentry));
994
995 ovl_start_write(dentry: c->dentry);
996 if (to_index) {
997 /* Initialize nlink for copy up of disconnected dentry */
998 err = ovl_set_nlink_upper(dentry: c->dentry);
999 } else {
1000 struct inode *udir = d_inode(dentry: c->destdir);
1001
1002 /* Restore timestamps on parent (best effort) */
1003 inode_lock(inode: udir);
1004 ovl_set_timestamps(ofs, upperdentry: c->destdir, stat: &c->pstat);
1005 inode_unlock(inode: udir);
1006
1007 ovl_dentry_set_upper_alias(dentry: c->dentry);
1008 ovl_dentry_update_reval(dentry: c->dentry, realdentry: ovl_dentry_upper(dentry: c->dentry));
1009 }
1010 ovl_end_write(dentry: c->dentry);
1011
1012out:
1013 if (to_index)
1014 kfree(objp: c->destname.name);
1015out_free_fh:
1016 kfree(objp: fh);
1017 return err;
1018}
1019
1020static bool ovl_need_meta_copy_up(struct dentry *dentry, umode_t mode,
1021 int flags)
1022{
1023 struct ovl_fs *ofs = OVL_FS(sb: dentry->d_sb);
1024
1025 if (!ofs->config.metacopy)
1026 return false;
1027
1028 if (!S_ISREG(mode))
1029 return false;
1030
1031 if (flags && ((OPEN_FMODE(flags) & FMODE_WRITE) || (flags & O_TRUNC)))
1032 return false;
1033
1034 /* Fall back to full copy if no fsverity on source data and we require verity */
1035 if (ofs->config.verity_mode == OVL_VERITY_REQUIRE) {
1036 struct path lowerdata;
1037
1038 ovl_path_lowerdata(dentry, path: &lowerdata);
1039
1040 if (WARN_ON_ONCE(lowerdata.dentry == NULL) ||
1041 ovl_ensure_verity_loaded(path: &lowerdata) ||
1042 !fsverity_active(inode: d_inode(dentry: lowerdata.dentry))) {
1043 return false;
1044 }
1045 }
1046
1047 return true;
1048}
1049
1050static ssize_t ovl_getxattr_value(const struct path *path, char *name, char **value)
1051{
1052 ssize_t res;
1053 char *buf;
1054
1055 res = ovl_do_getxattr(path, name, NULL, size: 0);
1056 if (res == -ENODATA || res == -EOPNOTSUPP)
1057 res = 0;
1058
1059 if (res > 0) {
1060 buf = kzalloc(res, GFP_KERNEL);
1061 if (!buf)
1062 return -ENOMEM;
1063
1064 res = ovl_do_getxattr(path, name, value: buf, size: res);
1065 if (res < 0)
1066 kfree(objp: buf);
1067 else
1068 *value = buf;
1069 }
1070 return res;
1071}
1072
1073/* Copy up data of an inode which was copied up metadata only in the past. */
1074static int ovl_copy_up_meta_inode_data(struct ovl_copy_up_ctx *c)
1075{
1076 struct ovl_fs *ofs = OVL_FS(sb: c->dentry->d_sb);
1077 struct path upperpath;
1078 int err;
1079 char *capability = NULL;
1080 ssize_t cap_size;
1081
1082 ovl_path_upper(dentry: c->dentry, path: &upperpath);
1083 if (WARN_ON(upperpath.dentry == NULL))
1084 return -EIO;
1085
1086 if (c->stat.size) {
1087 err = cap_size = ovl_getxattr_value(path: &upperpath, XATTR_NAME_CAPS,
1088 value: &capability);
1089 if (cap_size < 0)
1090 goto out;
1091 }
1092
1093 err = ovl_copy_up_data(c, temp: &upperpath);
1094 if (err)
1095 goto out_free;
1096
1097 /*
1098 * Writing to upper file will clear security.capability xattr. We
1099 * don't want that to happen for normal copy-up operation.
1100 */
1101 ovl_start_write(dentry: c->dentry);
1102 if (capability) {
1103 err = ovl_do_setxattr(ofs, dentry: upperpath.dentry, XATTR_NAME_CAPS,
1104 value: capability, size: cap_size, flags: 0);
1105 }
1106 if (!err) {
1107 err = ovl_removexattr(ofs, dentry: upperpath.dentry,
1108 ox: OVL_XATTR_METACOPY);
1109 }
1110 ovl_end_write(dentry: c->dentry);
1111 if (err)
1112 goto out_free;
1113
1114 ovl_clear_flag(flag: OVL_HAS_DIGEST, inode: d_inode(dentry: c->dentry));
1115 ovl_clear_flag(flag: OVL_VERIFIED_DIGEST, inode: d_inode(dentry: c->dentry));
1116 ovl_set_upperdata(inode: d_inode(dentry: c->dentry));
1117out_free:
1118 kfree(objp: capability);
1119out:
1120 return err;
1121}
1122
1123static int ovl_copy_up_one(struct dentry *parent, struct dentry *dentry,
1124 int flags)
1125{
1126 int err;
1127 DEFINE_DELAYED_CALL(done);
1128 struct path parentpath;
1129 struct ovl_copy_up_ctx ctx = {
1130 .parent = parent,
1131 .dentry = dentry,
1132 .workdir = ovl_workdir(dentry),
1133 };
1134
1135 if (WARN_ON(!ctx.workdir))
1136 return -EROFS;
1137
1138 ovl_path_lower(dentry, path: &ctx.lowerpath);
1139 err = vfs_getattr(&ctx.lowerpath, &ctx.stat,
1140 STATX_BASIC_STATS, AT_STATX_SYNC_AS_STAT);
1141 if (err)
1142 return err;
1143
1144 if (!kuid_has_mapping(current_user_ns(), uid: ctx.stat.uid) ||
1145 !kgid_has_mapping(current_user_ns(), gid: ctx.stat.gid))
1146 return -EOVERFLOW;
1147
1148 /*
1149 * With metacopy disabled, we fsync after final metadata copyup, for
1150 * both regular files and directories to get atomic copyup semantics
1151 * on filesystems that do not use strict metadata ordering (e.g. ubifs).
1152 *
1153 * With metacopy enabled we want to avoid fsync on all meta copyup
1154 * that will hurt performance of workloads such as chown -R, so we
1155 * only fsync on data copyup as legacy behavior.
1156 */
1157 ctx.metadata_fsync = !OVL_FS(sb: dentry->d_sb)->config.metacopy &&
1158 (S_ISREG(ctx.stat.mode) || S_ISDIR(ctx.stat.mode));
1159 ctx.metacopy = ovl_need_meta_copy_up(dentry, mode: ctx.stat.mode, flags);
1160
1161 if (parent) {
1162 ovl_path_upper(dentry: parent, path: &parentpath);
1163 ctx.destdir = parentpath.dentry;
1164
1165 err = vfs_getattr(&parentpath, &ctx.pstat,
1166 STATX_ATIME | STATX_MTIME,
1167 AT_STATX_SYNC_AS_STAT);
1168 if (err)
1169 return err;
1170 }
1171
1172 /* maybe truncate regular file. this has no effect on dirs */
1173 if (flags & O_TRUNC)
1174 ctx.stat.size = 0;
1175
1176 if (S_ISLNK(ctx.stat.mode)) {
1177 ctx.link = vfs_get_link(ctx.lowerpath.dentry, &done);
1178 if (IS_ERR(ptr: ctx.link))
1179 return PTR_ERR(ptr: ctx.link);
1180 }
1181
1182 err = ovl_copy_up_start(dentry, flags);
1183 /* err < 0: interrupted, err > 0: raced with another copy-up */
1184 if (unlikely(err)) {
1185 if (err > 0)
1186 err = 0;
1187 } else {
1188 if (!ovl_dentry_upper(dentry))
1189 err = ovl_do_copy_up(c: &ctx);
1190 if (!err && parent && !ovl_dentry_has_upper_alias(dentry))
1191 err = ovl_link_up(c: &ctx);
1192 if (!err && ovl_dentry_needs_data_copy_up_locked(dentry, flags))
1193 err = ovl_copy_up_meta_inode_data(c: &ctx);
1194 ovl_copy_up_end(dentry);
1195 }
1196 do_delayed_call(call: &done);
1197
1198 return err;
1199}
1200
1201static int ovl_copy_up_flags(struct dentry *dentry, int flags)
1202{
1203 int err = 0;
1204 bool disconnected = (dentry->d_flags & DCACHE_DISCONNECTED);
1205
1206 /*
1207 * With NFS export, copy up can get called for a disconnected non-dir.
1208 * In this case, we will copy up lower inode to index dir without
1209 * linking it to upper dir.
1210 */
1211 if (WARN_ON(disconnected && d_is_dir(dentry)))
1212 return -EIO;
1213
1214 /*
1215 * We may not need lowerdata if we are only doing metacopy up, but it is
1216 * not very important to optimize this case, so do lazy lowerdata lookup
1217 * before any copy up, so we can do it before taking ovl_inode_lock().
1218 */
1219 err = ovl_verify_lowerdata(dentry);
1220 if (err)
1221 return err;
1222
1223 while (!err) {
1224 struct dentry *next;
1225 struct dentry *parent = NULL;
1226
1227 if (ovl_already_copied_up(dentry, flags))
1228 break;
1229
1230 next = dget(dentry);
1231 /* find the topmost dentry not yet copied up */
1232 for (; !disconnected;) {
1233 parent = dget_parent(dentry: next);
1234
1235 if (ovl_dentry_upper(dentry: parent))
1236 break;
1237
1238 dput(next);
1239 next = parent;
1240 }
1241
1242 with_ovl_creds(dentry->d_sb)
1243 err = ovl_copy_up_one(parent, dentry: next, flags);
1244
1245 dput(parent);
1246 dput(next);
1247 }
1248
1249 return err;
1250}
1251
1252static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
1253{
1254 /* Copy up of disconnected dentry does not set upper alias */
1255 if (ovl_already_copied_up(dentry, flags))
1256 return false;
1257
1258 if (special_file(d_inode(dentry)->i_mode))
1259 return false;
1260
1261 if (!ovl_open_flags_need_copy_up(flags))
1262 return false;
1263
1264 return true;
1265}
1266
1267int ovl_maybe_copy_up(struct dentry *dentry, int flags)
1268{
1269 if (!ovl_open_need_copy_up(dentry, flags))
1270 return 0;
1271
1272 return ovl_copy_up_flags(dentry, flags);
1273}
1274
1275int ovl_copy_up_with_data(struct dentry *dentry)
1276{
1277 return ovl_copy_up_flags(dentry, O_WRONLY);
1278}
1279
1280int ovl_copy_up(struct dentry *dentry)
1281{
1282 return ovl_copy_up_flags(dentry, flags: 0);
1283}
1284

source code of linux/fs/overlayfs/copy_up.c