1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2017 Red Hat, Inc.
6 #include <linux/cred.h>
7 #include <linux/file.h>
8 #include <linux/mount.h>
9 #include <linux/xattr.h>
10 #include <linux/uio.h>
11 #include <linux/uaccess.h>
12 #include <linux/splice.h>
13 #include <linux/security.h>
16 #include "overlayfs.h"
21 struct kiocb
*orig_iocb
;
24 static struct kmem_cache
*ovl_aio_request_cachep
;
26 static char ovl_whatisit(struct inode
*inode
, struct inode
*realinode
)
28 if (realinode
!= ovl_inode_upper(inode
))
30 if (ovl_has_upperdata(inode
))
36 /* No atime modification on underlying */
37 #define OVL_OPEN_FLAGS (O_NOATIME)
39 static struct file
*ovl_open_realfile(const struct file
*file
,
40 const struct path
*realpath
)
42 struct inode
*realinode
= d_inode(realpath
->dentry
);
43 struct inode
*inode
= file_inode(file
);
44 struct mnt_idmap
*real_idmap
;
45 struct file
*realfile
;
46 const struct cred
*old_cred
;
47 int flags
= file
->f_flags
| OVL_OPEN_FLAGS
;
48 int acc_mode
= ACC_MODE(flags
);
52 acc_mode
|= MAY_APPEND
;
54 old_cred
= ovl_override_creds(inode
->i_sb
);
55 real_idmap
= mnt_idmap(realpath
->mnt
);
56 err
= inode_permission(real_idmap
, realinode
, MAY_OPEN
| acc_mode
);
58 realfile
= ERR_PTR(err
);
60 if (!inode_owner_or_capable(real_idmap
, realinode
))
63 realfile
= backing_file_open(&file
->f_path
, flags
, realpath
,
66 revert_creds(old_cred
);
68 pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
69 file
, file
, ovl_whatisit(inode
, realinode
), file
->f_flags
,
70 realfile
, IS_ERR(realfile
) ? 0 : realfile
->f_flags
);
75 #define OVL_SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT)
77 static int ovl_change_flags(struct file
*file
, unsigned int flags
)
79 struct inode
*inode
= file_inode(file
);
82 flags
&= OVL_SETFL_MASK
;
84 if (((flags
^ file
->f_flags
) & O_APPEND
) && IS_APPEND(inode
))
87 if ((flags
& O_DIRECT
) && !(file
->f_mode
& FMODE_CAN_ODIRECT
))
90 if (file
->f_op
->check_flags
) {
91 err
= file
->f_op
->check_flags(flags
);
96 spin_lock(&file
->f_lock
);
97 file
->f_flags
= (file
->f_flags
& ~OVL_SETFL_MASK
) | flags
;
98 file
->f_iocb_flags
= iocb_flags(file
);
99 spin_unlock(&file
->f_lock
);
104 static int ovl_real_fdget_meta(const struct file
*file
, struct fd
*real
,
107 struct dentry
*dentry
= file_dentry(file
);
108 struct path realpath
;
112 real
->file
= file
->private_data
;
115 ovl_path_real(dentry
, &realpath
);
117 /* lazy lookup and verify of lowerdata */
118 err
= ovl_verify_lowerdata(dentry
);
122 ovl_path_realdata(dentry
, &realpath
);
124 if (!realpath
.dentry
)
127 /* Has it been copied up since we'd opened it? */
128 if (unlikely(file_inode(real
->file
) != d_inode(realpath
.dentry
))) {
129 real
->flags
= FDPUT_FPUT
;
130 real
->file
= ovl_open_realfile(file
, &realpath
);
132 return PTR_ERR_OR_ZERO(real
->file
);
135 /* Did the flags change since open? */
136 if (unlikely((file
->f_flags
^ real
->file
->f_flags
) & ~OVL_OPEN_FLAGS
))
137 return ovl_change_flags(real
->file
, file
->f_flags
);
142 static int ovl_real_fdget(const struct file
*file
, struct fd
*real
)
144 if (d_is_dir(file_dentry(file
))) {
146 real
->file
= ovl_dir_real_file(file
, false);
148 return PTR_ERR_OR_ZERO(real
->file
);
151 return ovl_real_fdget_meta(file
, real
, false);
154 static int ovl_open(struct inode
*inode
, struct file
*file
)
156 struct dentry
*dentry
= file_dentry(file
);
157 struct file
*realfile
;
158 struct path realpath
;
161 /* lazy lookup and verify lowerdata */
162 err
= ovl_verify_lowerdata(dentry
);
166 err
= ovl_maybe_copy_up(dentry
, file
->f_flags
);
170 /* No longer need these flags, so don't pass them on to underlying fs */
171 file
->f_flags
&= ~(O_CREAT
| O_EXCL
| O_NOCTTY
| O_TRUNC
);
173 ovl_path_realdata(dentry
, &realpath
);
174 if (!realpath
.dentry
)
177 realfile
= ovl_open_realfile(file
, &realpath
);
178 if (IS_ERR(realfile
))
179 return PTR_ERR(realfile
);
181 file
->private_data
= realfile
;
186 static int ovl_release(struct inode
*inode
, struct file
*file
)
188 fput(file
->private_data
);
193 static loff_t
ovl_llseek(struct file
*file
, loff_t offset
, int whence
)
195 struct inode
*inode
= file_inode(file
);
197 const struct cred
*old_cred
;
201 * The two special cases below do not need to involve real fs,
202 * so we can optimizing concurrent callers.
205 if (whence
== SEEK_CUR
)
208 if (whence
== SEEK_SET
)
209 return vfs_setpos(file
, 0, 0);
212 ret
= ovl_real_fdget(file
, &real
);
217 * Overlay file f_pos is the master copy that is preserved
218 * through copy up and modified on read/write, but only real
219 * fs knows how to SEEK_HOLE/SEEK_DATA and real fs may impose
220 * limitations that are more strict than ->s_maxbytes for specific
221 * files, so we use the real file to perform seeks.
223 ovl_inode_lock(inode
);
224 real
.file
->f_pos
= file
->f_pos
;
226 old_cred
= ovl_override_creds(inode
->i_sb
);
227 ret
= vfs_llseek(real
.file
, offset
, whence
);
228 revert_creds(old_cred
);
230 file
->f_pos
= real
.file
->f_pos
;
231 ovl_inode_unlock(inode
);
238 static void ovl_file_accessed(struct file
*file
)
240 struct inode
*inode
, *upperinode
;
241 struct timespec64 ctime
, uctime
;
243 if (file
->f_flags
& O_NOATIME
)
246 inode
= file_inode(file
);
247 upperinode
= ovl_inode_upper(inode
);
252 ctime
= inode_get_ctime(inode
);
253 uctime
= inode_get_ctime(upperinode
);
254 if ((!timespec64_equal(&inode
->i_mtime
, &upperinode
->i_mtime
) ||
255 !timespec64_equal(&ctime
, &uctime
))) {
256 inode
->i_mtime
= upperinode
->i_mtime
;
257 inode_set_ctime_to_ts(inode
, uctime
);
260 touch_atime(&file
->f_path
);
263 static rwf_t
ovl_iocb_to_rwf(int ifl
)
267 if (ifl
& IOCB_NOWAIT
)
269 if (ifl
& IOCB_HIPRI
)
271 if (ifl
& IOCB_DSYNC
)
279 static inline void ovl_aio_put(struct ovl_aio_req
*aio_req
)
281 if (refcount_dec_and_test(&aio_req
->ref
)) {
282 fput(aio_req
->iocb
.ki_filp
);
283 kmem_cache_free(ovl_aio_request_cachep
, aio_req
);
287 static void ovl_aio_cleanup_handler(struct ovl_aio_req
*aio_req
)
289 struct kiocb
*iocb
= &aio_req
->iocb
;
290 struct kiocb
*orig_iocb
= aio_req
->orig_iocb
;
292 if (iocb
->ki_flags
& IOCB_WRITE
) {
293 struct inode
*inode
= file_inode(orig_iocb
->ki_filp
);
295 kiocb_end_write(iocb
);
299 orig_iocb
->ki_pos
= iocb
->ki_pos
;
300 ovl_aio_put(aio_req
);
303 static void ovl_aio_rw_complete(struct kiocb
*iocb
, long res
)
305 struct ovl_aio_req
*aio_req
= container_of(iocb
,
306 struct ovl_aio_req
, iocb
);
307 struct kiocb
*orig_iocb
= aio_req
->orig_iocb
;
309 ovl_aio_cleanup_handler(aio_req
);
310 orig_iocb
->ki_complete(orig_iocb
, res
);
313 static ssize_t
ovl_read_iter(struct kiocb
*iocb
, struct iov_iter
*iter
)
315 struct file
*file
= iocb
->ki_filp
;
317 const struct cred
*old_cred
;
320 if (!iov_iter_count(iter
))
323 ret
= ovl_real_fdget(file
, &real
);
328 if (iocb
->ki_flags
& IOCB_DIRECT
&&
329 !(real
.file
->f_mode
& FMODE_CAN_ODIRECT
))
332 old_cred
= ovl_override_creds(file_inode(file
)->i_sb
);
333 if (is_sync_kiocb(iocb
)) {
334 ret
= vfs_iter_read(real
.file
, iter
, &iocb
->ki_pos
,
335 ovl_iocb_to_rwf(iocb
->ki_flags
));
337 struct ovl_aio_req
*aio_req
;
340 aio_req
= kmem_cache_zalloc(ovl_aio_request_cachep
, GFP_KERNEL
);
344 aio_req
->orig_iocb
= iocb
;
345 kiocb_clone(&aio_req
->iocb
, iocb
, get_file(real
.file
));
346 aio_req
->iocb
.ki_complete
= ovl_aio_rw_complete
;
347 refcount_set(&aio_req
->ref
, 2);
348 ret
= vfs_iocb_iter_read(real
.file
, &aio_req
->iocb
, iter
);
349 ovl_aio_put(aio_req
);
350 if (ret
!= -EIOCBQUEUED
)
351 ovl_aio_cleanup_handler(aio_req
);
354 revert_creds(old_cred
);
355 ovl_file_accessed(file
);
362 static ssize_t
ovl_write_iter(struct kiocb
*iocb
, struct iov_iter
*iter
)
364 struct file
*file
= iocb
->ki_filp
;
365 struct inode
*inode
= file_inode(file
);
367 const struct cred
*old_cred
;
369 int ifl
= iocb
->ki_flags
;
371 if (!iov_iter_count(iter
))
377 ret
= file_remove_privs(file
);
381 ret
= ovl_real_fdget(file
, &real
);
386 if (iocb
->ki_flags
& IOCB_DIRECT
&&
387 !(real
.file
->f_mode
& FMODE_CAN_ODIRECT
))
390 if (!ovl_should_sync(OVL_FS(inode
->i_sb
)))
391 ifl
&= ~(IOCB_DSYNC
| IOCB_SYNC
);
394 * Overlayfs doesn't support deferred completions, don't copy
395 * this property in case it is set by the issuer.
397 ifl
&= ~IOCB_DIO_CALLER_COMP
;
399 old_cred
= ovl_override_creds(file_inode(file
)->i_sb
);
400 if (is_sync_kiocb(iocb
)) {
401 file_start_write(real
.file
);
402 ret
= vfs_iter_write(real
.file
, iter
, &iocb
->ki_pos
,
403 ovl_iocb_to_rwf(ifl
));
404 file_end_write(real
.file
);
408 struct ovl_aio_req
*aio_req
;
411 aio_req
= kmem_cache_zalloc(ovl_aio_request_cachep
, GFP_KERNEL
);
415 aio_req
->orig_iocb
= iocb
;
416 kiocb_clone(&aio_req
->iocb
, iocb
, get_file(real
.file
));
417 aio_req
->iocb
.ki_flags
= ifl
;
418 aio_req
->iocb
.ki_complete
= ovl_aio_rw_complete
;
419 refcount_set(&aio_req
->ref
, 2);
420 kiocb_start_write(&aio_req
->iocb
);
421 ret
= vfs_iocb_iter_write(real
.file
, &aio_req
->iocb
, iter
);
422 ovl_aio_put(aio_req
);
423 if (ret
!= -EIOCBQUEUED
)
424 ovl_aio_cleanup_handler(aio_req
);
427 revert_creds(old_cred
);
437 static ssize_t
ovl_splice_read(struct file
*in
, loff_t
*ppos
,
438 struct pipe_inode_info
*pipe
, size_t len
,
441 const struct cred
*old_cred
;
445 ret
= ovl_real_fdget(in
, &real
);
449 old_cred
= ovl_override_creds(file_inode(in
)->i_sb
);
450 ret
= vfs_splice_read(real
.file
, ppos
, pipe
, len
, flags
);
451 revert_creds(old_cred
);
452 ovl_file_accessed(in
);
459 * Calling iter_file_splice_write() directly from overlay's f_op may deadlock
460 * due to lock order inversion between pipe->mutex in iter_file_splice_write()
461 * and file_start_write(real.file) in ovl_write_iter().
463 * So do everything ovl_write_iter() does and call iter_file_splice_write() on
466 static ssize_t
ovl_splice_write(struct pipe_inode_info
*pipe
, struct file
*out
,
467 loff_t
*ppos
, size_t len
, unsigned int flags
)
470 const struct cred
*old_cred
;
471 struct inode
*inode
= file_inode(out
);
477 ret
= file_remove_privs(out
);
481 ret
= ovl_real_fdget(out
, &real
);
485 old_cred
= ovl_override_creds(inode
->i_sb
);
486 file_start_write(real
.file
);
488 ret
= iter_file_splice_write(pipe
, real
.file
, ppos
, len
, flags
);
490 file_end_write(real
.file
);
493 revert_creds(old_cred
);
502 static int ovl_fsync(struct file
*file
, loff_t start
, loff_t end
, int datasync
)
505 const struct cred
*old_cred
;
508 ret
= ovl_sync_status(OVL_FS(file_inode(file
)->i_sb
));
512 ret
= ovl_real_fdget_meta(file
, &real
, !datasync
);
516 /* Don't sync lower file for fear of receiving EROFS error */
517 if (file_inode(real
.file
) == ovl_inode_upper(file_inode(file
))) {
518 old_cred
= ovl_override_creds(file_inode(file
)->i_sb
);
519 ret
= vfs_fsync_range(real
.file
, start
, end
, datasync
);
520 revert_creds(old_cred
);
528 static int ovl_mmap(struct file
*file
, struct vm_area_struct
*vma
)
530 struct file
*realfile
= file
->private_data
;
531 const struct cred
*old_cred
;
534 if (!realfile
->f_op
->mmap
)
537 if (WARN_ON(file
!= vma
->vm_file
))
540 vma_set_file(vma
, realfile
);
542 old_cred
= ovl_override_creds(file_inode(file
)->i_sb
);
543 ret
= call_mmap(vma
->vm_file
, vma
);
544 revert_creds(old_cred
);
545 ovl_file_accessed(file
);
550 static long ovl_fallocate(struct file
*file
, int mode
, loff_t offset
, loff_t len
)
552 struct inode
*inode
= file_inode(file
);
554 const struct cred
*old_cred
;
560 ret
= file_remove_privs(file
);
564 ret
= ovl_real_fdget(file
, &real
);
568 old_cred
= ovl_override_creds(file_inode(file
)->i_sb
);
569 ret
= vfs_fallocate(real
.file
, mode
, offset
, len
);
570 revert_creds(old_cred
);
583 static int ovl_fadvise(struct file
*file
, loff_t offset
, loff_t len
, int advice
)
586 const struct cred
*old_cred
;
589 ret
= ovl_real_fdget(file
, &real
);
593 old_cred
= ovl_override_creds(file_inode(file
)->i_sb
);
594 ret
= vfs_fadvise(real
.file
, offset
, len
, advice
);
595 revert_creds(old_cred
);
608 static loff_t
ovl_copyfile(struct file
*file_in
, loff_t pos_in
,
609 struct file
*file_out
, loff_t pos_out
,
610 loff_t len
, unsigned int flags
, enum ovl_copyop op
)
612 struct inode
*inode_out
= file_inode(file_out
);
613 struct fd real_in
, real_out
;
614 const struct cred
*old_cred
;
617 inode_lock(inode_out
);
618 if (op
!= OVL_DEDUPE
) {
620 ovl_copyattr(inode_out
);
621 ret
= file_remove_privs(file_out
);
626 ret
= ovl_real_fdget(file_out
, &real_out
);
630 ret
= ovl_real_fdget(file_in
, &real_in
);
636 old_cred
= ovl_override_creds(file_inode(file_out
)->i_sb
);
639 ret
= vfs_copy_file_range(real_in
.file
, pos_in
,
640 real_out
.file
, pos_out
, len
, flags
);
644 ret
= vfs_clone_file_range(real_in
.file
, pos_in
,
645 real_out
.file
, pos_out
, len
, flags
);
649 ret
= vfs_dedupe_file_range_one(real_in
.file
, pos_in
,
650 real_out
.file
, pos_out
, len
,
654 revert_creds(old_cred
);
657 ovl_copyattr(inode_out
);
663 inode_unlock(inode_out
);
668 static ssize_t
ovl_copy_file_range(struct file
*file_in
, loff_t pos_in
,
669 struct file
*file_out
, loff_t pos_out
,
670 size_t len
, unsigned int flags
)
672 return ovl_copyfile(file_in
, pos_in
, file_out
, pos_out
, len
, flags
,
676 static loff_t
ovl_remap_file_range(struct file
*file_in
, loff_t pos_in
,
677 struct file
*file_out
, loff_t pos_out
,
678 loff_t len
, unsigned int remap_flags
)
682 if (remap_flags
& ~(REMAP_FILE_DEDUP
| REMAP_FILE_ADVISORY
))
685 if (remap_flags
& REMAP_FILE_DEDUP
)
691 * Don't copy up because of a dedupe request, this wouldn't make sense
692 * most of the time (data would be duplicated instead of deduplicated).
694 if (op
== OVL_DEDUPE
&&
695 (!ovl_inode_upper(file_inode(file_in
)) ||
696 !ovl_inode_upper(file_inode(file_out
))))
699 return ovl_copyfile(file_in
, pos_in
, file_out
, pos_out
, len
,
703 static int ovl_flush(struct file
*file
, fl_owner_t id
)
706 const struct cred
*old_cred
;
709 err
= ovl_real_fdget(file
, &real
);
713 if (real
.file
->f_op
->flush
) {
714 old_cred
= ovl_override_creds(file_inode(file
)->i_sb
);
715 err
= real
.file
->f_op
->flush(real
.file
, id
);
716 revert_creds(old_cred
);
723 const struct file_operations ovl_file_operations
= {
725 .release
= ovl_release
,
726 .llseek
= ovl_llseek
,
727 .read_iter
= ovl_read_iter
,
728 .write_iter
= ovl_write_iter
,
731 .fallocate
= ovl_fallocate
,
732 .fadvise
= ovl_fadvise
,
734 .splice_read
= ovl_splice_read
,
735 .splice_write
= ovl_splice_write
,
737 .copy_file_range
= ovl_copy_file_range
,
738 .remap_file_range
= ovl_remap_file_range
,
741 int __init
ovl_aio_request_cache_init(void)
743 ovl_aio_request_cachep
= kmem_cache_create("ovl_aio_req",
744 sizeof(struct ovl_aio_req
),
745 0, SLAB_HWCACHE_ALIGN
, NULL
);
746 if (!ovl_aio_request_cachep
)
752 void ovl_aio_request_cache_destroy(void)
754 kmem_cache_destroy(ovl_aio_request_cachep
);