1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992 Linus Torvalds
8 #include <linux/string.h>
10 #include <linux/file.h>
11 #include <linux/fdtable.h>
12 #include <linux/fsnotify.h>
13 #include <linux/module.h>
14 #include <linux/tty.h>
15 #include <linux/namei.h>
16 #include <linux/backing-dev.h>
17 #include <linux/capability.h>
18 #include <linux/securebits.h>
19 #include <linux/security.h>
20 #include <linux/mount.h>
21 #include <linux/fcntl.h>
22 #include <linux/slab.h>
23 #include <linux/uaccess.h>
25 #include <linux/personality.h>
26 #include <linux/pagemap.h>
27 #include <linux/syscalls.h>
28 #include <linux/rcupdate.h>
29 #include <linux/audit.h>
30 #include <linux/falloc.h>
31 #include <linux/fs_struct.h>
32 #include <linux/ima.h>
33 #include <linux/dnotify.h>
34 #include <linux/compat.h>
38 #define CREATE_TRACE_POINTS
39 #include <trace/events/fs.h>
41 int do_truncate(struct dentry
*dentry
, loff_t length
, unsigned int time_attrs
,
45 struct iattr newattrs
;
47 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
51 newattrs
.ia_size
= length
;
52 newattrs
.ia_valid
= ATTR_SIZE
| time_attrs
;
54 newattrs
.ia_file
= filp
;
55 newattrs
.ia_valid
|= ATTR_FILE
;
58 /* Remove suid, sgid, and file capabilities on truncate too */
59 ret
= dentry_needs_remove_privs(dentry
);
63 newattrs
.ia_valid
|= ret
| ATTR_FORCE
;
65 inode_lock(dentry
->d_inode
);
66 /* Note any delegations or leases have already been broken: */
67 ret
= notify_change(dentry
, &newattrs
, NULL
);
68 inode_unlock(dentry
->d_inode
);
71 EXPORT_SYMBOL_GPL(do_truncate
);
73 long vfs_truncate(const struct path
*path
, loff_t length
)
78 inode
= path
->dentry
->d_inode
;
80 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
81 if (S_ISDIR(inode
->i_mode
))
83 if (!S_ISREG(inode
->i_mode
))
86 error
= mnt_want_write(path
->mnt
);
90 error
= inode_permission(inode
, MAY_WRITE
);
92 goto mnt_drop_write_and_out
;
96 goto mnt_drop_write_and_out
;
98 error
= get_write_access(inode
);
100 goto mnt_drop_write_and_out
;
103 * Make sure that there are no leases. get_write_access() protects
104 * against the truncate racing with a lease-granting setlease().
106 error
= break_lease(inode
, O_WRONLY
);
108 goto put_write_and_out
;
110 error
= locks_verify_truncate(inode
, NULL
, length
);
112 error
= security_path_truncate(path
);
114 error
= do_truncate(path
->dentry
, length
, 0, NULL
);
117 put_write_access(inode
);
118 mnt_drop_write_and_out
:
119 mnt_drop_write(path
->mnt
);
123 EXPORT_SYMBOL_GPL(vfs_truncate
);
125 long do_sys_truncate(const char __user
*pathname
, loff_t length
)
127 unsigned int lookup_flags
= LOOKUP_FOLLOW
;
131 if (length
< 0) /* sorry, but loff_t says... */
135 error
= user_path_at(AT_FDCWD
, pathname
, lookup_flags
, &path
);
137 error
= vfs_truncate(&path
, length
);
140 if (retry_estale(error
, lookup_flags
)) {
141 lookup_flags
|= LOOKUP_REVAL
;
147 SYSCALL_DEFINE2(truncate
, const char __user
*, path
, long, length
)
149 return do_sys_truncate(path
, length
);
153 COMPAT_SYSCALL_DEFINE2(truncate
, const char __user
*, path
, compat_off_t
, length
)
155 return do_sys_truncate(path
, length
);
159 long do_sys_ftruncate(unsigned int fd
, loff_t length
, int small
)
162 struct dentry
*dentry
;
174 /* explicitly opened as large or we are on 64-bit box */
175 if (f
.file
->f_flags
& O_LARGEFILE
)
178 dentry
= f
.file
->f_path
.dentry
;
179 inode
= dentry
->d_inode
;
181 if (!S_ISREG(inode
->i_mode
) || !(f
.file
->f_mode
& FMODE_WRITE
))
185 /* Cannot ftruncate over 2^31 bytes without large file support */
186 if (small
&& length
> MAX_NON_LFS
)
190 /* Check IS_APPEND on real upper inode */
191 if (IS_APPEND(file_inode(f
.file
)))
194 sb_start_write(inode
->i_sb
);
195 error
= locks_verify_truncate(inode
, f
.file
, length
);
197 error
= security_path_truncate(&f
.file
->f_path
);
199 error
= do_truncate(dentry
, length
, ATTR_MTIME
|ATTR_CTIME
, f
.file
);
200 sb_end_write(inode
->i_sb
);
207 SYSCALL_DEFINE2(ftruncate
, unsigned int, fd
, unsigned long, length
)
209 return do_sys_ftruncate(fd
, length
, 1);
213 COMPAT_SYSCALL_DEFINE2(ftruncate
, unsigned int, fd
, compat_ulong_t
, length
)
215 return do_sys_ftruncate(fd
, length
, 1);
219 /* LFS versions of truncate are only needed on 32 bit machines */
220 #if BITS_PER_LONG == 32
221 SYSCALL_DEFINE2(truncate64
, const char __user
*, path
, loff_t
, length
)
223 return do_sys_truncate(path
, length
);
226 SYSCALL_DEFINE2(ftruncate64
, unsigned int, fd
, loff_t
, length
)
228 return do_sys_ftruncate(fd
, length
, 0);
230 #endif /* BITS_PER_LONG == 32 */
233 int vfs_fallocate(struct file
*file
, int mode
, loff_t offset
, loff_t len
)
235 struct inode
*inode
= file_inode(file
);
238 if (offset
< 0 || len
<= 0)
241 /* Return error if mode is not supported */
242 if (mode
& ~FALLOC_FL_SUPPORTED_MASK
)
245 /* Punch hole and zero range are mutually exclusive */
246 if ((mode
& (FALLOC_FL_PUNCH_HOLE
| FALLOC_FL_ZERO_RANGE
)) ==
247 (FALLOC_FL_PUNCH_HOLE
| FALLOC_FL_ZERO_RANGE
))
250 /* Punch hole must have keep size set */
251 if ((mode
& FALLOC_FL_PUNCH_HOLE
) &&
252 !(mode
& FALLOC_FL_KEEP_SIZE
))
255 /* Collapse range should only be used exclusively. */
256 if ((mode
& FALLOC_FL_COLLAPSE_RANGE
) &&
257 (mode
& ~FALLOC_FL_COLLAPSE_RANGE
))
260 /* Insert range should only be used exclusively. */
261 if ((mode
& FALLOC_FL_INSERT_RANGE
) &&
262 (mode
& ~FALLOC_FL_INSERT_RANGE
))
265 /* Unshare range should only be used with allocate mode. */
266 if ((mode
& FALLOC_FL_UNSHARE_RANGE
) &&
267 (mode
& ~(FALLOC_FL_UNSHARE_RANGE
| FALLOC_FL_KEEP_SIZE
)))
270 if (!(file
->f_mode
& FMODE_WRITE
))
274 * We can only allow pure fallocate on append only files
276 if ((mode
& ~FALLOC_FL_KEEP_SIZE
) && IS_APPEND(inode
))
279 if (IS_IMMUTABLE(inode
))
283 * We cannot allow any fallocate operation on an active swapfile
285 if (IS_SWAPFILE(inode
))
289 * Revalidate the write permissions, in case security policy has
290 * changed since the files were opened.
292 ret
= security_file_permission(file
, MAY_WRITE
);
296 if (S_ISFIFO(inode
->i_mode
))
299 if (S_ISDIR(inode
->i_mode
))
302 if (!S_ISREG(inode
->i_mode
) && !S_ISBLK(inode
->i_mode
))
305 /* Check for wrap through zero too */
306 if (((offset
+ len
) > inode
->i_sb
->s_maxbytes
) || ((offset
+ len
) < 0))
309 if (!file
->f_op
->fallocate
)
312 file_start_write(file
);
313 ret
= file
->f_op
->fallocate(file
, mode
, offset
, len
);
316 * Create inotify and fanotify events.
318 * To keep the logic simple always create events if fallocate succeeds.
319 * This implies that events are even created if the file size remains
320 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
323 fsnotify_modify(file
);
325 file_end_write(file
);
328 EXPORT_SYMBOL_GPL(vfs_fallocate
);
330 int ksys_fallocate(int fd
, int mode
, loff_t offset
, loff_t len
)
332 struct fd f
= fdget(fd
);
336 error
= vfs_fallocate(f
.file
, mode
, offset
, len
);
342 SYSCALL_DEFINE4(fallocate
, int, fd
, int, mode
, loff_t
, offset
, loff_t
, len
)
344 return ksys_fallocate(fd
, mode
, offset
, len
);
348 * access() needs to use the real uid/gid, not the effective uid/gid.
349 * We do this by temporarily clearing all FS-related capabilities and
350 * switching the fsuid/fsgid around to the real ones.
352 long do_faccessat(int dfd
, const char __user
*filename
, int mode
)
354 const struct cred
*old_cred
;
355 struct cred
*override_cred
;
359 unsigned int lookup_flags
= LOOKUP_FOLLOW
;
361 if (mode
& ~S_IRWXO
) /* where's F_OK, X_OK, W_OK, R_OK? */
364 override_cred
= prepare_creds();
368 override_cred
->fsuid
= override_cred
->uid
;
369 override_cred
->fsgid
= override_cred
->gid
;
371 if (!issecure(SECURE_NO_SETUID_FIXUP
)) {
372 /* Clear the capabilities if we switch to a non-root user */
373 kuid_t root_uid
= make_kuid(override_cred
->user_ns
, 0);
374 if (!uid_eq(override_cred
->uid
, root_uid
))
375 cap_clear(override_cred
->cap_effective
);
377 override_cred
->cap_effective
=
378 override_cred
->cap_permitted
;
382 * The new set of credentials can *only* be used in
383 * task-synchronous circumstances, and does not need
384 * RCU freeing, unless somebody then takes a separate
387 * NOTE! This is _only_ true because this credential
388 * is used purely for override_creds() that installs
389 * it as the subjective cred. Other threads will be
390 * accessing ->real_cred, not the subjective cred.
392 * If somebody _does_ make a copy of this (using the
393 * 'get_current_cred()' function), that will clear the
394 * non_rcu field, because now that other user may be
395 * expecting RCU freeing. But normal thread-synchronous
396 * cred accesses will keep things non-RCY.
398 override_cred
->non_rcu
= 1;
400 old_cred
= override_creds(override_cred
);
402 res
= user_path_at(dfd
, filename
, lookup_flags
, &path
);
406 inode
= d_backing_inode(path
.dentry
);
408 if ((mode
& MAY_EXEC
) && S_ISREG(inode
->i_mode
)) {
410 * MAY_EXEC on regular files is denied if the fs is mounted
411 * with the "noexec" flag.
414 if (path_noexec(&path
))
415 goto out_path_release
;
418 res
= inode_permission(inode
, mode
| MAY_ACCESS
);
419 /* SuS v2 requires we report a read only fs too */
420 if (res
|| !(mode
& S_IWOTH
) || special_file(inode
->i_mode
))
421 goto out_path_release
;
423 * This is a rare case where using __mnt_is_readonly()
424 * is OK without a mnt_want/drop_write() pair. Since
425 * no actual write to the fs is performed here, we do
426 * not need to telegraph to that to anyone.
428 * By doing this, we accept that this access is
429 * inherently racy and know that the fs may change
430 * state before we even see this result.
432 if (__mnt_is_readonly(path
.mnt
))
437 if (retry_estale(res
, lookup_flags
)) {
438 lookup_flags
|= LOOKUP_REVAL
;
442 revert_creds(old_cred
);
443 put_cred(override_cred
);
447 SYSCALL_DEFINE3(faccessat
, int, dfd
, const char __user
*, filename
, int, mode
)
449 return do_faccessat(dfd
, filename
, mode
);
452 SYSCALL_DEFINE2(access
, const char __user
*, filename
, int, mode
)
454 return do_faccessat(AT_FDCWD
, filename
, mode
);
457 int ksys_chdir(const char __user
*filename
)
461 unsigned int lookup_flags
= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
463 error
= user_path_at(AT_FDCWD
, filename
, lookup_flags
, &path
);
467 error
= inode_permission(path
.dentry
->d_inode
, MAY_EXEC
| MAY_CHDIR
);
471 set_fs_pwd(current
->fs
, &path
);
475 if (retry_estale(error
, lookup_flags
)) {
476 lookup_flags
|= LOOKUP_REVAL
;
483 SYSCALL_DEFINE1(chdir
, const char __user
*, filename
)
485 return ksys_chdir(filename
);
488 SYSCALL_DEFINE1(fchdir
, unsigned int, fd
)
490 struct fd f
= fdget_raw(fd
);
498 if (!d_can_lookup(f
.file
->f_path
.dentry
))
501 error
= inode_permission(file_inode(f
.file
), MAY_EXEC
| MAY_CHDIR
);
503 set_fs_pwd(current
->fs
, &f
.file
->f_path
);
510 int ksys_chroot(const char __user
*filename
)
514 unsigned int lookup_flags
= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
516 error
= user_path_at(AT_FDCWD
, filename
, lookup_flags
, &path
);
520 error
= inode_permission(path
.dentry
->d_inode
, MAY_EXEC
| MAY_CHDIR
);
525 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT
))
527 error
= security_path_chroot(&path
);
531 set_fs_root(current
->fs
, &path
);
535 if (retry_estale(error
, lookup_flags
)) {
536 lookup_flags
|= LOOKUP_REVAL
;
543 SYSCALL_DEFINE1(chroot
, const char __user
*, filename
)
545 return ksys_chroot(filename
);
548 static int chmod_common(const struct path
*path
, umode_t mode
)
550 struct inode
*inode
= path
->dentry
->d_inode
;
551 struct inode
*delegated_inode
= NULL
;
552 struct iattr newattrs
;
555 error
= mnt_want_write(path
->mnt
);
560 error
= security_path_chmod(path
, mode
);
563 newattrs
.ia_mode
= (mode
& S_IALLUGO
) | (inode
->i_mode
& ~S_IALLUGO
);
564 newattrs
.ia_valid
= ATTR_MODE
| ATTR_CTIME
;
565 error
= notify_change(path
->dentry
, &newattrs
, &delegated_inode
);
568 if (delegated_inode
) {
569 error
= break_deleg_wait(&delegated_inode
);
573 mnt_drop_write(path
->mnt
);
577 int ksys_fchmod(unsigned int fd
, umode_t mode
)
579 struct fd f
= fdget(fd
);
584 err
= chmod_common(&f
.file
->f_path
, mode
);
590 SYSCALL_DEFINE2(fchmod
, unsigned int, fd
, umode_t
, mode
)
592 return ksys_fchmod(fd
, mode
);
595 int do_fchmodat(int dfd
, const char __user
*filename
, umode_t mode
)
599 unsigned int lookup_flags
= LOOKUP_FOLLOW
;
601 error
= user_path_at(dfd
, filename
, lookup_flags
, &path
);
603 error
= chmod_common(&path
, mode
);
605 if (retry_estale(error
, lookup_flags
)) {
606 lookup_flags
|= LOOKUP_REVAL
;
613 SYSCALL_DEFINE3(fchmodat
, int, dfd
, const char __user
*, filename
,
616 return do_fchmodat(dfd
, filename
, mode
);
619 SYSCALL_DEFINE2(chmod
, const char __user
*, filename
, umode_t
, mode
)
621 return do_fchmodat(AT_FDCWD
, filename
, mode
);
624 static int chown_common(const struct path
*path
, uid_t user
, gid_t group
)
626 struct inode
*inode
= path
->dentry
->d_inode
;
627 struct inode
*delegated_inode
= NULL
;
629 struct iattr newattrs
;
633 uid
= make_kuid(current_user_ns(), user
);
634 gid
= make_kgid(current_user_ns(), group
);
637 newattrs
.ia_valid
= ATTR_CTIME
;
638 if (user
!= (uid_t
) -1) {
641 newattrs
.ia_valid
|= ATTR_UID
;
642 newattrs
.ia_uid
= uid
;
644 if (group
!= (gid_t
) -1) {
647 newattrs
.ia_valid
|= ATTR_GID
;
648 newattrs
.ia_gid
= gid
;
650 if (!S_ISDIR(inode
->i_mode
))
652 ATTR_KILL_SUID
| ATTR_KILL_SGID
| ATTR_KILL_PRIV
;
654 error
= security_path_chown(path
, uid
, gid
);
656 error
= notify_change(path
->dentry
, &newattrs
, &delegated_inode
);
658 if (delegated_inode
) {
659 error
= break_deleg_wait(&delegated_inode
);
666 int do_fchownat(int dfd
, const char __user
*filename
, uid_t user
, gid_t group
,
673 if ((flag
& ~(AT_SYMLINK_NOFOLLOW
| AT_EMPTY_PATH
)) != 0)
676 lookup_flags
= (flag
& AT_SYMLINK_NOFOLLOW
) ? 0 : LOOKUP_FOLLOW
;
677 if (flag
& AT_EMPTY_PATH
)
678 lookup_flags
|= LOOKUP_EMPTY
;
680 error
= user_path_at(dfd
, filename
, lookup_flags
, &path
);
683 error
= mnt_want_write(path
.mnt
);
686 error
= chown_common(&path
, user
, group
);
687 mnt_drop_write(path
.mnt
);
690 if (retry_estale(error
, lookup_flags
)) {
691 lookup_flags
|= LOOKUP_REVAL
;
698 SYSCALL_DEFINE5(fchownat
, int, dfd
, const char __user
*, filename
, uid_t
, user
,
699 gid_t
, group
, int, flag
)
701 return do_fchownat(dfd
, filename
, user
, group
, flag
);
704 SYSCALL_DEFINE3(chown
, const char __user
*, filename
, uid_t
, user
, gid_t
, group
)
706 return do_fchownat(AT_FDCWD
, filename
, user
, group
, 0);
709 SYSCALL_DEFINE3(lchown
, const char __user
*, filename
, uid_t
, user
, gid_t
, group
)
711 return do_fchownat(AT_FDCWD
, filename
, user
, group
,
712 AT_SYMLINK_NOFOLLOW
);
715 int ksys_fchown(unsigned int fd
, uid_t user
, gid_t group
)
717 struct fd f
= fdget(fd
);
723 error
= mnt_want_write_file(f
.file
);
727 error
= chown_common(&f
.file
->f_path
, user
, group
);
728 mnt_drop_write_file(f
.file
);
735 SYSCALL_DEFINE3(fchown
, unsigned int, fd
, uid_t
, user
, gid_t
, group
)
737 return ksys_fchown(fd
, user
, group
);
740 static int do_dentry_open(struct file
*f
,
742 int (*open
)(struct inode
*, struct file
*))
744 static const struct file_operations empty_fops
= {};
747 path_get(&f
->f_path
);
749 f
->f_mapping
= inode
->i_mapping
;
751 /* Ensure that we skip any errors that predate opening of the file */
752 f
->f_wb_err
= filemap_sample_wb_err(f
->f_mapping
);
754 if (unlikely(f
->f_flags
& O_PATH
)) {
755 f
->f_mode
= FMODE_PATH
| FMODE_OPENED
;
756 f
->f_op
= &empty_fops
;
760 /* Any file opened for execve()/uselib() has to be a regular file. */
761 if (unlikely(f
->f_flags
& FMODE_EXEC
&& !S_ISREG(inode
->i_mode
))) {
766 if (f
->f_mode
& FMODE_WRITE
&& !special_file(inode
->i_mode
)) {
767 error
= get_write_access(inode
);
770 error
= __mnt_want_write(f
->f_path
.mnt
);
771 if (unlikely(error
)) {
772 put_write_access(inode
);
775 f
->f_mode
|= FMODE_WRITER
;
778 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
779 if (S_ISREG(inode
->i_mode
) || S_ISDIR(inode
->i_mode
))
780 f
->f_mode
|= FMODE_ATOMIC_POS
;
782 f
->f_op
= fops_get(inode
->i_fop
);
783 if (WARN_ON(!f
->f_op
)) {
788 error
= security_file_open(f
);
792 error
= break_lease(locks_inode(f
), f
->f_flags
);
796 /* normally all 3 are set; ->open() can clear them if needed */
797 f
->f_mode
|= FMODE_LSEEK
| FMODE_PREAD
| FMODE_PWRITE
;
799 open
= f
->f_op
->open
;
801 error
= open(inode
, f
);
805 f
->f_mode
|= FMODE_OPENED
;
806 if ((f
->f_mode
& (FMODE_READ
| FMODE_WRITE
)) == FMODE_READ
)
807 i_readcount_inc(inode
);
808 if ((f
->f_mode
& FMODE_READ
) &&
809 likely(f
->f_op
->read
|| f
->f_op
->read_iter
))
810 f
->f_mode
|= FMODE_CAN_READ
;
811 if ((f
->f_mode
& FMODE_WRITE
) &&
812 likely(f
->f_op
->write
|| f
->f_op
->write_iter
))
813 f
->f_mode
|= FMODE_CAN_WRITE
;
815 f
->f_write_hint
= WRITE_LIFE_NOT_SET
;
816 f
->f_flags
&= ~(O_CREAT
| O_EXCL
| O_NOCTTY
| O_TRUNC
);
818 file_ra_state_init(&f
->f_ra
, f
->f_mapping
->host
->i_mapping
);
820 /* NB: we're sure to have correct a_ops only after f_op->open */
821 if (f
->f_flags
& O_DIRECT
) {
822 if (!f
->f_mapping
->a_ops
|| !f
->f_mapping
->a_ops
->direct_IO
)
827 * XXX: Huge page cache doesn't support writing yet. Drop all page
828 * cache for this file before processing writes.
830 if ((f
->f_mode
& FMODE_WRITE
) && filemap_nr_thps(inode
->i_mapping
))
831 truncate_pagecache(inode
, 0);
836 if (WARN_ON_ONCE(error
> 0))
839 if (f
->f_mode
& FMODE_WRITER
) {
840 put_write_access(inode
);
841 __mnt_drop_write(f
->f_path
.mnt
);
844 path_put(&f
->f_path
);
845 f
->f_path
.mnt
= NULL
;
846 f
->f_path
.dentry
= NULL
;
852 * finish_open - finish opening a file
853 * @file: file pointer
854 * @dentry: pointer to dentry
855 * @open: open callback
856 * @opened: state of open
858 * This can be used to finish opening a file passed to i_op->atomic_open().
860 * If the open callback is set to NULL, then the standard f_op->open()
861 * filesystem callback is substituted.
863 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
864 * the return value of d_splice_alias(), then the caller needs to perform dput()
865 * on it after finish_open().
867 * Returns zero on success or -errno if the open failed.
869 int finish_open(struct file
*file
, struct dentry
*dentry
,
870 int (*open
)(struct inode
*, struct file
*))
872 BUG_ON(file
->f_mode
& FMODE_OPENED
); /* once it's opened, it's opened */
874 file
->f_path
.dentry
= dentry
;
875 return do_dentry_open(file
, d_backing_inode(dentry
), open
);
877 EXPORT_SYMBOL(finish_open
);
880 * finish_no_open - finish ->atomic_open() without opening the file
882 * @file: file pointer
883 * @dentry: dentry or NULL (as returned from ->lookup())
885 * This can be used to set the result of a successful lookup in ->atomic_open().
887 * NB: unlike finish_open() this function does consume the dentry reference and
888 * the caller need not dput() it.
890 * Returns "0" which must be the return value of ->atomic_open() after having
891 * called this function.
893 int finish_no_open(struct file
*file
, struct dentry
*dentry
)
895 file
->f_path
.dentry
= dentry
;
898 EXPORT_SYMBOL(finish_no_open
);
900 char *file_path(struct file
*filp
, char *buf
, int buflen
)
902 return d_path(&filp
->f_path
, buf
, buflen
);
904 EXPORT_SYMBOL(file_path
);
907 * vfs_open - open the file at the given path
908 * @path: path to open
909 * @file: newly allocated file with f_flag initialized
910 * @cred: credentials to use
912 int vfs_open(const struct path
*path
, struct file
*file
)
914 file
->f_path
= *path
;
915 return do_dentry_open(file
, d_backing_inode(path
->dentry
), NULL
);
918 struct file
*dentry_open(const struct path
*path
, int flags
,
919 const struct cred
*cred
)
924 validate_creds(cred
);
926 /* We must always pass in a valid mount pointer. */
929 f
= alloc_empty_file(flags
, cred
);
931 error
= vfs_open(path
, f
);
939 EXPORT_SYMBOL(dentry_open
);
941 struct file
*open_with_fake_path(const struct path
*path
, int flags
,
942 struct inode
*inode
, const struct cred
*cred
)
944 struct file
*f
= alloc_empty_file_noaccount(flags
, cred
);
949 error
= do_dentry_open(f
, inode
, NULL
);
957 EXPORT_SYMBOL(open_with_fake_path
);
959 static inline int build_open_flags(int flags
, umode_t mode
, struct open_flags
*op
)
961 int lookup_flags
= 0;
962 int acc_mode
= ACC_MODE(flags
);
965 * Clear out all open flags we don't know about so that we don't report
966 * them in fcntl(F_GETFD) or similar interfaces.
968 flags
&= VALID_OPEN_FLAGS
;
970 if (flags
& (O_CREAT
| __O_TMPFILE
))
971 op
->mode
= (mode
& S_IALLUGO
) | S_IFREG
;
975 /* Must never be set by userspace */
976 flags
&= ~FMODE_NONOTIFY
& ~O_CLOEXEC
;
979 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
980 * check for O_DSYNC if the need any syncing at all we enforce it's
981 * always set instead of having to deal with possibly weird behaviour
982 * for malicious applications setting only __O_SYNC.
984 if (flags
& __O_SYNC
)
987 if (flags
& __O_TMPFILE
) {
988 if ((flags
& O_TMPFILE_MASK
) != O_TMPFILE
)
990 if (!(acc_mode
& MAY_WRITE
))
992 } else if (flags
& O_PATH
) {
994 * If we have O_PATH in the open flag. Then we
995 * cannot have anything other than the below set of flags
997 flags
&= O_DIRECTORY
| O_NOFOLLOW
| O_PATH
;
1001 op
->open_flag
= flags
;
1003 /* O_TRUNC implies we need access checks for write permissions */
1004 if (flags
& O_TRUNC
)
1005 acc_mode
|= MAY_WRITE
;
1007 /* Allow the LSM permission hook to distinguish append
1008 access from general write access. */
1009 if (flags
& O_APPEND
)
1010 acc_mode
|= MAY_APPEND
;
1012 op
->acc_mode
= acc_mode
;
1014 op
->intent
= flags
& O_PATH
? 0 : LOOKUP_OPEN
;
1016 if (flags
& O_CREAT
) {
1017 op
->intent
|= LOOKUP_CREATE
;
1019 op
->intent
|= LOOKUP_EXCL
;
1022 if (flags
& O_DIRECTORY
)
1023 lookup_flags
|= LOOKUP_DIRECTORY
;
1024 if (!(flags
& O_NOFOLLOW
))
1025 lookup_flags
|= LOOKUP_FOLLOW
;
1026 op
->lookup_flags
= lookup_flags
;
1031 * file_open_name - open file and return file pointer
1033 * @name: struct filename containing path to open
1034 * @flags: open flags as per the open(2) second argument
1035 * @mode: mode for the new file if O_CREAT is set, else ignored
1037 * This is the helper to open a file from kernelspace if you really
1038 * have to. But in generally you should not do this, so please move
1039 * along, nothing to see here..
1041 struct file
*file_open_name(struct filename
*name
, int flags
, umode_t mode
)
1043 struct open_flags op
;
1044 int err
= build_open_flags(flags
, mode
, &op
);
1045 return err
? ERR_PTR(err
) : do_filp_open(AT_FDCWD
, name
, &op
);
1049 * filp_open - open file and return file pointer
1051 * @filename: path to open
1052 * @flags: open flags as per the open(2) second argument
1053 * @mode: mode for the new file if O_CREAT is set, else ignored
1055 * This is the helper to open a file from kernelspace if you really
1056 * have to. But in generally you should not do this, so please move
1057 * along, nothing to see here..
1059 struct file
*filp_open(const char *filename
, int flags
, umode_t mode
)
1061 struct filename
*name
= getname_kernel(filename
);
1062 struct file
*file
= ERR_CAST(name
);
1064 if (!IS_ERR(name
)) {
1065 file
= file_open_name(name
, flags
, mode
);
1070 EXPORT_SYMBOL(filp_open
);
1072 struct file
*file_open_root(struct dentry
*dentry
, struct vfsmount
*mnt
,
1073 const char *filename
, int flags
, umode_t mode
)
1075 struct open_flags op
;
1076 int err
= build_open_flags(flags
, mode
, &op
);
1078 return ERR_PTR(err
);
1079 return do_file_open_root(dentry
, mnt
, filename
, &op
);
1081 EXPORT_SYMBOL(file_open_root
);
1083 long do_sys_open(int dfd
, const char __user
*filename
, int flags
, umode_t mode
)
1085 struct open_flags op
;
1086 int fd
= build_open_flags(flags
, mode
, &op
);
1087 struct filename
*tmp
;
1092 tmp
= getname(filename
);
1094 return PTR_ERR(tmp
);
1096 fd
= get_unused_fd_flags(flags
);
1098 struct file
*f
= do_filp_open(dfd
, tmp
, &op
);
1105 trace_do_sys_open(tmp
->name
, flags
, mode
);
1112 SYSCALL_DEFINE3(open
, const char __user
*, filename
, int, flags
, umode_t
, mode
)
1114 if (force_o_largefile())
1115 flags
|= O_LARGEFILE
;
1117 return do_sys_open(AT_FDCWD
, filename
, flags
, mode
);
1120 SYSCALL_DEFINE4(openat
, int, dfd
, const char __user
*, filename
, int, flags
,
1123 if (force_o_largefile())
1124 flags
|= O_LARGEFILE
;
1126 return do_sys_open(dfd
, filename
, flags
, mode
);
1129 #ifdef CONFIG_COMPAT
1131 * Exactly like sys_open(), except that it doesn't set the
1134 COMPAT_SYSCALL_DEFINE3(open
, const char __user
*, filename
, int, flags
, umode_t
, mode
)
1136 return do_sys_open(AT_FDCWD
, filename
, flags
, mode
);
1140 * Exactly like sys_openat(), except that it doesn't set the
1143 COMPAT_SYSCALL_DEFINE4(openat
, int, dfd
, const char __user
*, filename
, int, flags
, umode_t
, mode
)
1145 return do_sys_open(dfd
, filename
, flags
, mode
);
1152 * For backward compatibility? Maybe this should be moved
1153 * into arch/i386 instead?
1155 SYSCALL_DEFINE2(creat
, const char __user
*, pathname
, umode_t
, mode
)
1157 return ksys_open(pathname
, O_CREAT
| O_WRONLY
| O_TRUNC
, mode
);
1163 * "id" is the POSIX thread ID. We use the
1164 * files pointer for this..
1166 int filp_close(struct file
*filp
, fl_owner_t id
)
1170 if (!file_count(filp
)) {
1171 printk(KERN_ERR
"VFS: Close: file count is 0\n");
1175 if (filp
->f_op
->flush
)
1176 retval
= filp
->f_op
->flush(filp
, id
);
1178 if (likely(!(filp
->f_mode
& FMODE_PATH
))) {
1179 dnotify_flush(filp
, id
);
1180 locks_remove_posix(filp
, id
);
1186 EXPORT_SYMBOL(filp_close
);
1189 * Careful here! We test whether the file pointer is NULL before
1190 * releasing the fd. This ensures that one clone task can't release
1191 * an fd while another clone is opening it.
1193 SYSCALL_DEFINE1(close
, unsigned int, fd
)
1195 int retval
= __close_fd(current
->files
, fd
);
1197 /* can't restart close syscall because file table entry was cleared */
1198 if (unlikely(retval
== -ERESTARTSYS
||
1199 retval
== -ERESTARTNOINTR
||
1200 retval
== -ERESTARTNOHAND
||
1201 retval
== -ERESTART_RESTARTBLOCK
))
1208 * This routine simulates a hangup on the tty, to arrange that users
1209 * are given clean terminals at login time.
1211 SYSCALL_DEFINE0(vhangup
)
1213 if (capable(CAP_SYS_TTY_CONFIG
)) {
1221 * Called when an inode is about to be open.
1222 * We use this to disallow opening large files on 32bit systems if
1223 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1224 * on this flag in sys_open.
1226 int generic_file_open(struct inode
* inode
, struct file
* filp
)
1228 if (!(filp
->f_flags
& O_LARGEFILE
) && i_size_read(inode
) > MAX_NON_LFS
)
1233 EXPORT_SYMBOL(generic_file_open
);
1236 * This is used by subsystems that don't want seekable
1237 * file descriptors. The function is not supposed to ever fail, the only
1238 * reason it returns an 'int' and not 'void' is so that it can be plugged
1239 * directly into file_operations structure.
1241 int nonseekable_open(struct inode
*inode
, struct file
*filp
)
1243 filp
->f_mode
&= ~(FMODE_LSEEK
| FMODE_PREAD
| FMODE_PWRITE
);
1247 EXPORT_SYMBOL(nonseekable_open
);
1250 * stream_open is used by subsystems that want stream-like file descriptors.
1251 * Such file descriptors are not seekable and don't have notion of position
1252 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1253 * Contrary to file descriptors of other regular files, .read() and .write()
1254 * can run simultaneously.
1256 * stream_open never fails and is marked to return int so that it could be
1257 * directly used as file_operations.open .
1259 int stream_open(struct inode
*inode
, struct file
*filp
)
1261 filp
->f_mode
&= ~(FMODE_LSEEK
| FMODE_PREAD
| FMODE_PWRITE
| FMODE_ATOMIC_POS
);
1262 filp
->f_mode
|= FMODE_STREAM
;
1266 EXPORT_SYMBOL(stream_open
);