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>
35 #include <linux/mnt_idmapping.h>
36 #include <linux/filelock.h>
40 int do_truncate(struct mnt_idmap
*idmap
, struct dentry
*dentry
,
41 loff_t length
, unsigned int time_attrs
, struct file
*filp
)
44 struct iattr newattrs
;
46 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
50 newattrs
.ia_size
= length
;
51 newattrs
.ia_valid
= ATTR_SIZE
| time_attrs
;
53 newattrs
.ia_file
= filp
;
54 newattrs
.ia_valid
|= ATTR_FILE
;
57 /* Remove suid, sgid, and file capabilities on truncate too */
58 ret
= dentry_needs_remove_privs(idmap
, dentry
);
62 newattrs
.ia_valid
|= ret
| ATTR_FORCE
;
64 inode_lock(dentry
->d_inode
);
65 /* Note any delegations or leases have already been broken: */
66 ret
= notify_change(idmap
, dentry
, &newattrs
, NULL
);
67 inode_unlock(dentry
->d_inode
);
71 long vfs_truncate(const struct path
*path
, loff_t length
)
73 struct mnt_idmap
*idmap
;
77 inode
= path
->dentry
->d_inode
;
79 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
80 if (S_ISDIR(inode
->i_mode
))
82 if (!S_ISREG(inode
->i_mode
))
85 error
= mnt_want_write(path
->mnt
);
89 idmap
= mnt_idmap(path
->mnt
);
90 error
= inode_permission(idmap
, 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
= security_path_truncate(path
);
112 error
= do_truncate(idmap
, path
->dentry
, length
, 0, NULL
);
115 put_write_access(inode
);
116 mnt_drop_write_and_out
:
117 mnt_drop_write(path
->mnt
);
121 EXPORT_SYMBOL_GPL(vfs_truncate
);
123 long do_sys_truncate(const char __user
*pathname
, loff_t length
)
125 unsigned int lookup_flags
= LOOKUP_FOLLOW
;
129 if (length
< 0) /* sorry, but loff_t says... */
133 error
= user_path_at(AT_FDCWD
, pathname
, lookup_flags
, &path
);
135 error
= vfs_truncate(&path
, length
);
138 if (retry_estale(error
, lookup_flags
)) {
139 lookup_flags
|= LOOKUP_REVAL
;
145 SYSCALL_DEFINE2(truncate
, const char __user
*, path
, long, length
)
147 return do_sys_truncate(path
, length
);
151 COMPAT_SYSCALL_DEFINE2(truncate
, const char __user
*, path
, compat_off_t
, length
)
153 return do_sys_truncate(path
, length
);
157 long do_sys_ftruncate(unsigned int fd
, loff_t length
, int small
)
160 struct dentry
*dentry
;
172 /* explicitly opened as large or we are on 64-bit box */
173 if (f
.file
->f_flags
& O_LARGEFILE
)
176 dentry
= f
.file
->f_path
.dentry
;
177 inode
= dentry
->d_inode
;
179 if (!S_ISREG(inode
->i_mode
) || !(f
.file
->f_mode
& FMODE_WRITE
))
183 /* Cannot ftruncate over 2^31 bytes without large file support */
184 if (small
&& length
> MAX_NON_LFS
)
188 /* Check IS_APPEND on real upper inode */
189 if (IS_APPEND(file_inode(f
.file
)))
191 sb_start_write(inode
->i_sb
);
192 error
= security_file_truncate(f
.file
);
194 error
= do_truncate(file_mnt_idmap(f
.file
), dentry
, length
,
195 ATTR_MTIME
| ATTR_CTIME
, f
.file
);
196 sb_end_write(inode
->i_sb
);
203 SYSCALL_DEFINE2(ftruncate
, unsigned int, fd
, unsigned long, length
)
205 return do_sys_ftruncate(fd
, length
, 1);
209 COMPAT_SYSCALL_DEFINE2(ftruncate
, unsigned int, fd
, compat_ulong_t
, length
)
211 return do_sys_ftruncate(fd
, length
, 1);
215 /* LFS versions of truncate are only needed on 32 bit machines */
216 #if BITS_PER_LONG == 32
217 SYSCALL_DEFINE2(truncate64
, const char __user
*, path
, loff_t
, length
)
219 return do_sys_truncate(path
, length
);
222 SYSCALL_DEFINE2(ftruncate64
, unsigned int, fd
, loff_t
, length
)
224 return do_sys_ftruncate(fd
, length
, 0);
226 #endif /* BITS_PER_LONG == 32 */
228 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64)
229 COMPAT_SYSCALL_DEFINE3(truncate64
, const char __user
*, pathname
,
230 compat_arg_u64_dual(length
))
232 return ksys_truncate(pathname
, compat_arg_u64_glue(length
));
236 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64)
237 COMPAT_SYSCALL_DEFINE3(ftruncate64
, unsigned int, fd
,
238 compat_arg_u64_dual(length
))
240 return ksys_ftruncate(fd
, compat_arg_u64_glue(length
));
244 int vfs_fallocate(struct file
*file
, int mode
, loff_t offset
, loff_t len
)
246 struct inode
*inode
= file_inode(file
);
249 if (offset
< 0 || len
<= 0)
252 /* Return error if mode is not supported */
253 if (mode
& ~FALLOC_FL_SUPPORTED_MASK
)
256 /* Punch hole and zero range are mutually exclusive */
257 if ((mode
& (FALLOC_FL_PUNCH_HOLE
| FALLOC_FL_ZERO_RANGE
)) ==
258 (FALLOC_FL_PUNCH_HOLE
| FALLOC_FL_ZERO_RANGE
))
261 /* Punch hole must have keep size set */
262 if ((mode
& FALLOC_FL_PUNCH_HOLE
) &&
263 !(mode
& FALLOC_FL_KEEP_SIZE
))
266 /* Collapse range should only be used exclusively. */
267 if ((mode
& FALLOC_FL_COLLAPSE_RANGE
) &&
268 (mode
& ~FALLOC_FL_COLLAPSE_RANGE
))
271 /* Insert range should only be used exclusively. */
272 if ((mode
& FALLOC_FL_INSERT_RANGE
) &&
273 (mode
& ~FALLOC_FL_INSERT_RANGE
))
276 /* Unshare range should only be used with allocate mode. */
277 if ((mode
& FALLOC_FL_UNSHARE_RANGE
) &&
278 (mode
& ~(FALLOC_FL_UNSHARE_RANGE
| FALLOC_FL_KEEP_SIZE
)))
281 if (!(file
->f_mode
& FMODE_WRITE
))
285 * We can only allow pure fallocate on append only files
287 if ((mode
& ~FALLOC_FL_KEEP_SIZE
) && IS_APPEND(inode
))
290 if (IS_IMMUTABLE(inode
))
294 * We cannot allow any fallocate operation on an active swapfile
296 if (IS_SWAPFILE(inode
))
300 * Revalidate the write permissions, in case security policy has
301 * changed since the files were opened.
303 ret
= security_file_permission(file
, MAY_WRITE
);
307 ret
= fsnotify_file_area_perm(file
, MAY_WRITE
, &offset
, len
);
311 if (S_ISFIFO(inode
->i_mode
))
314 if (S_ISDIR(inode
->i_mode
))
317 if (!S_ISREG(inode
->i_mode
) && !S_ISBLK(inode
->i_mode
))
320 /* Check for wrap through zero too */
321 if (((offset
+ len
) > inode
->i_sb
->s_maxbytes
) || ((offset
+ len
) < 0))
324 if (!file
->f_op
->fallocate
)
327 file_start_write(file
);
328 ret
= file
->f_op
->fallocate(file
, mode
, offset
, len
);
331 * Create inotify and fanotify events.
333 * To keep the logic simple always create events if fallocate succeeds.
334 * This implies that events are even created if the file size remains
335 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
338 fsnotify_modify(file
);
340 file_end_write(file
);
343 EXPORT_SYMBOL_GPL(vfs_fallocate
);
345 int ksys_fallocate(int fd
, int mode
, loff_t offset
, loff_t len
)
347 struct fd f
= fdget(fd
);
351 error
= vfs_fallocate(f
.file
, mode
, offset
, len
);
357 SYSCALL_DEFINE4(fallocate
, int, fd
, int, mode
, loff_t
, offset
, loff_t
, len
)
359 return ksys_fallocate(fd
, mode
, offset
, len
);
362 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE)
363 COMPAT_SYSCALL_DEFINE6(fallocate
, int, fd
, int, mode
, compat_arg_u64_dual(offset
),
364 compat_arg_u64_dual(len
))
366 return ksys_fallocate(fd
, mode
, compat_arg_u64_glue(offset
),
367 compat_arg_u64_glue(len
));
372 * access() needs to use the real uid/gid, not the effective uid/gid.
373 * We do this by temporarily clearing all FS-related capabilities and
374 * switching the fsuid/fsgid around to the real ones.
376 * Creating new credentials is expensive, so we try to skip doing it,
377 * which we can if the result would match what we already got.
379 static bool access_need_override_creds(int flags
)
381 const struct cred
*cred
;
383 if (flags
& AT_EACCESS
)
386 cred
= current_cred();
387 if (!uid_eq(cred
->fsuid
, cred
->uid
) ||
388 !gid_eq(cred
->fsgid
, cred
->gid
))
391 if (!issecure(SECURE_NO_SETUID_FIXUP
)) {
392 kuid_t root_uid
= make_kuid(cred
->user_ns
, 0);
393 if (!uid_eq(cred
->uid
, root_uid
)) {
394 if (!cap_isclear(cred
->cap_effective
))
397 if (!cap_isidentical(cred
->cap_effective
,
398 cred
->cap_permitted
))
406 static const struct cred
*access_override_creds(void)
408 const struct cred
*old_cred
;
409 struct cred
*override_cred
;
411 override_cred
= prepare_creds();
416 * XXX access_need_override_creds performs checks in hopes of skipping
417 * this work. Make sure it stays in sync if making any changes in this
421 override_cred
->fsuid
= override_cred
->uid
;
422 override_cred
->fsgid
= override_cred
->gid
;
424 if (!issecure(SECURE_NO_SETUID_FIXUP
)) {
425 /* Clear the capabilities if we switch to a non-root user */
426 kuid_t root_uid
= make_kuid(override_cred
->user_ns
, 0);
427 if (!uid_eq(override_cred
->uid
, root_uid
))
428 cap_clear(override_cred
->cap_effective
);
430 override_cred
->cap_effective
=
431 override_cred
->cap_permitted
;
435 * The new set of credentials can *only* be used in
436 * task-synchronous circumstances, and does not need
437 * RCU freeing, unless somebody then takes a separate
440 * NOTE! This is _only_ true because this credential
441 * is used purely for override_creds() that installs
442 * it as the subjective cred. Other threads will be
443 * accessing ->real_cred, not the subjective cred.
445 * If somebody _does_ make a copy of this (using the
446 * 'get_current_cred()' function), that will clear the
447 * non_rcu field, because now that other user may be
448 * expecting RCU freeing. But normal thread-synchronous
449 * cred accesses will keep things non-racy to avoid RCU
452 override_cred
->non_rcu
= 1;
454 old_cred
= override_creds(override_cred
);
456 /* override_cred() gets its own ref */
457 put_cred(override_cred
);
462 static long do_faccessat(int dfd
, const char __user
*filename
, int mode
, int flags
)
467 unsigned int lookup_flags
= LOOKUP_FOLLOW
;
468 const struct cred
*old_cred
= NULL
;
470 if (mode
& ~S_IRWXO
) /* where's F_OK, X_OK, W_OK, R_OK? */
473 if (flags
& ~(AT_EACCESS
| AT_SYMLINK_NOFOLLOW
| AT_EMPTY_PATH
))
476 if (flags
& AT_SYMLINK_NOFOLLOW
)
477 lookup_flags
&= ~LOOKUP_FOLLOW
;
478 if (flags
& AT_EMPTY_PATH
)
479 lookup_flags
|= LOOKUP_EMPTY
;
481 if (access_need_override_creds(flags
)) {
482 old_cred
= access_override_creds();
488 res
= user_path_at(dfd
, filename
, lookup_flags
, &path
);
492 inode
= d_backing_inode(path
.dentry
);
494 if ((mode
& MAY_EXEC
) && S_ISREG(inode
->i_mode
)) {
496 * MAY_EXEC on regular files is denied if the fs is mounted
497 * with the "noexec" flag.
500 if (path_noexec(&path
))
501 goto out_path_release
;
504 res
= inode_permission(mnt_idmap(path
.mnt
), inode
, mode
| MAY_ACCESS
);
505 /* SuS v2 requires we report a read only fs too */
506 if (res
|| !(mode
& S_IWOTH
) || special_file(inode
->i_mode
))
507 goto out_path_release
;
509 * This is a rare case where using __mnt_is_readonly()
510 * is OK without a mnt_want/drop_write() pair. Since
511 * no actual write to the fs is performed here, we do
512 * not need to telegraph to that to anyone.
514 * By doing this, we accept that this access is
515 * inherently racy and know that the fs may change
516 * state before we even see this result.
518 if (__mnt_is_readonly(path
.mnt
))
523 if (retry_estale(res
, lookup_flags
)) {
524 lookup_flags
|= LOOKUP_REVAL
;
529 revert_creds(old_cred
);
534 SYSCALL_DEFINE3(faccessat
, int, dfd
, const char __user
*, filename
, int, mode
)
536 return do_faccessat(dfd
, filename
, mode
, 0);
539 SYSCALL_DEFINE4(faccessat2
, int, dfd
, const char __user
*, filename
, int, mode
,
542 return do_faccessat(dfd
, filename
, mode
, flags
);
545 SYSCALL_DEFINE2(access
, const char __user
*, filename
, int, mode
)
547 return do_faccessat(AT_FDCWD
, filename
, mode
, 0);
550 SYSCALL_DEFINE1(chdir
, const char __user
*, filename
)
554 unsigned int lookup_flags
= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
556 error
= user_path_at(AT_FDCWD
, filename
, lookup_flags
, &path
);
560 error
= path_permission(&path
, MAY_EXEC
| MAY_CHDIR
);
564 set_fs_pwd(current
->fs
, &path
);
568 if (retry_estale(error
, lookup_flags
)) {
569 lookup_flags
|= LOOKUP_REVAL
;
576 SYSCALL_DEFINE1(fchdir
, unsigned int, fd
)
578 struct fd f
= fdget_raw(fd
);
586 if (!d_can_lookup(f
.file
->f_path
.dentry
))
589 error
= file_permission(f
.file
, MAY_EXEC
| MAY_CHDIR
);
591 set_fs_pwd(current
->fs
, &f
.file
->f_path
);
598 SYSCALL_DEFINE1(chroot
, const char __user
*, filename
)
602 unsigned int lookup_flags
= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
604 error
= user_path_at(AT_FDCWD
, filename
, lookup_flags
, &path
);
608 error
= path_permission(&path
, MAY_EXEC
| MAY_CHDIR
);
613 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT
))
615 error
= security_path_chroot(&path
);
619 set_fs_root(current
->fs
, &path
);
623 if (retry_estale(error
, lookup_flags
)) {
624 lookup_flags
|= LOOKUP_REVAL
;
631 int chmod_common(const struct path
*path
, umode_t mode
)
633 struct inode
*inode
= path
->dentry
->d_inode
;
634 struct inode
*delegated_inode
= NULL
;
635 struct iattr newattrs
;
638 error
= mnt_want_write(path
->mnt
);
643 error
= security_path_chmod(path
, mode
);
646 newattrs
.ia_mode
= (mode
& S_IALLUGO
) | (inode
->i_mode
& ~S_IALLUGO
);
647 newattrs
.ia_valid
= ATTR_MODE
| ATTR_CTIME
;
648 error
= notify_change(mnt_idmap(path
->mnt
), path
->dentry
,
649 &newattrs
, &delegated_inode
);
652 if (delegated_inode
) {
653 error
= break_deleg_wait(&delegated_inode
);
657 mnt_drop_write(path
->mnt
);
661 int vfs_fchmod(struct file
*file
, umode_t mode
)
664 return chmod_common(&file
->f_path
, mode
);
667 SYSCALL_DEFINE2(fchmod
, unsigned int, fd
, umode_t
, mode
)
669 struct fd f
= fdget(fd
);
673 err
= vfs_fchmod(f
.file
, mode
);
679 static int do_fchmodat(int dfd
, const char __user
*filename
, umode_t mode
,
684 unsigned int lookup_flags
;
686 if (unlikely(flags
& ~(AT_SYMLINK_NOFOLLOW
| AT_EMPTY_PATH
)))
689 lookup_flags
= (flags
& AT_SYMLINK_NOFOLLOW
) ? 0 : LOOKUP_FOLLOW
;
690 if (flags
& AT_EMPTY_PATH
)
691 lookup_flags
|= LOOKUP_EMPTY
;
694 error
= user_path_at(dfd
, filename
, lookup_flags
, &path
);
696 error
= chmod_common(&path
, mode
);
698 if (retry_estale(error
, lookup_flags
)) {
699 lookup_flags
|= LOOKUP_REVAL
;
706 SYSCALL_DEFINE4(fchmodat2
, int, dfd
, const char __user
*, filename
,
707 umode_t
, mode
, unsigned int, flags
)
709 return do_fchmodat(dfd
, filename
, mode
, flags
);
712 SYSCALL_DEFINE3(fchmodat
, int, dfd
, const char __user
*, filename
,
715 return do_fchmodat(dfd
, filename
, mode
, 0);
718 SYSCALL_DEFINE2(chmod
, const char __user
*, filename
, umode_t
, mode
)
720 return do_fchmodat(AT_FDCWD
, filename
, mode
, 0);
724 * Check whether @kuid is valid and if so generate and set vfsuid_t in
727 * Return: true if @kuid is valid, false if not.
729 static inline bool setattr_vfsuid(struct iattr
*attr
, kuid_t kuid
)
731 if (!uid_valid(kuid
))
733 attr
->ia_valid
|= ATTR_UID
;
734 attr
->ia_vfsuid
= VFSUIDT_INIT(kuid
);
739 * Check whether @kgid is valid and if so generate and set vfsgid_t in
742 * Return: true if @kgid is valid, false if not.
744 static inline bool setattr_vfsgid(struct iattr
*attr
, kgid_t kgid
)
746 if (!gid_valid(kgid
))
748 attr
->ia_valid
|= ATTR_GID
;
749 attr
->ia_vfsgid
= VFSGIDT_INIT(kgid
);
753 int chown_common(const struct path
*path
, uid_t user
, gid_t group
)
755 struct mnt_idmap
*idmap
;
756 struct user_namespace
*fs_userns
;
757 struct inode
*inode
= path
->dentry
->d_inode
;
758 struct inode
*delegated_inode
= NULL
;
760 struct iattr newattrs
;
764 uid
= make_kuid(current_user_ns(), user
);
765 gid
= make_kgid(current_user_ns(), group
);
767 idmap
= mnt_idmap(path
->mnt
);
768 fs_userns
= i_user_ns(inode
);
771 newattrs
.ia_vfsuid
= INVALID_VFSUID
;
772 newattrs
.ia_vfsgid
= INVALID_VFSGID
;
773 newattrs
.ia_valid
= ATTR_CTIME
;
774 if ((user
!= (uid_t
)-1) && !setattr_vfsuid(&newattrs
, uid
))
776 if ((group
!= (gid_t
)-1) && !setattr_vfsgid(&newattrs
, gid
))
779 if (!S_ISDIR(inode
->i_mode
))
780 newattrs
.ia_valid
|= ATTR_KILL_SUID
| ATTR_KILL_PRIV
|
781 setattr_should_drop_sgid(idmap
, inode
);
782 /* Continue to send actual fs values, not the mount values. */
783 error
= security_path_chown(
785 from_vfsuid(idmap
, fs_userns
, newattrs
.ia_vfsuid
),
786 from_vfsgid(idmap
, fs_userns
, newattrs
.ia_vfsgid
));
788 error
= notify_change(idmap
, path
->dentry
, &newattrs
,
791 if (delegated_inode
) {
792 error
= break_deleg_wait(&delegated_inode
);
799 int do_fchownat(int dfd
, const char __user
*filename
, uid_t user
, gid_t group
,
806 if ((flag
& ~(AT_SYMLINK_NOFOLLOW
| AT_EMPTY_PATH
)) != 0)
809 lookup_flags
= (flag
& AT_SYMLINK_NOFOLLOW
) ? 0 : LOOKUP_FOLLOW
;
810 if (flag
& AT_EMPTY_PATH
)
811 lookup_flags
|= LOOKUP_EMPTY
;
813 error
= user_path_at(dfd
, filename
, lookup_flags
, &path
);
816 error
= mnt_want_write(path
.mnt
);
819 error
= chown_common(&path
, user
, group
);
820 mnt_drop_write(path
.mnt
);
823 if (retry_estale(error
, lookup_flags
)) {
824 lookup_flags
|= LOOKUP_REVAL
;
831 SYSCALL_DEFINE5(fchownat
, int, dfd
, const char __user
*, filename
, uid_t
, user
,
832 gid_t
, group
, int, flag
)
834 return do_fchownat(dfd
, filename
, user
, group
, flag
);
837 SYSCALL_DEFINE3(chown
, const char __user
*, filename
, uid_t
, user
, gid_t
, group
)
839 return do_fchownat(AT_FDCWD
, filename
, user
, group
, 0);
842 SYSCALL_DEFINE3(lchown
, const char __user
*, filename
, uid_t
, user
, gid_t
, group
)
844 return do_fchownat(AT_FDCWD
, filename
, user
, group
,
845 AT_SYMLINK_NOFOLLOW
);
848 int vfs_fchown(struct file
*file
, uid_t user
, gid_t group
)
852 error
= mnt_want_write_file(file
);
856 error
= chown_common(&file
->f_path
, user
, group
);
857 mnt_drop_write_file(file
);
861 int ksys_fchown(unsigned int fd
, uid_t user
, gid_t group
)
863 struct fd f
= fdget(fd
);
867 error
= vfs_fchown(f
.file
, user
, group
);
873 SYSCALL_DEFINE3(fchown
, unsigned int, fd
, uid_t
, user
, gid_t
, group
)
875 return ksys_fchown(fd
, user
, group
);
878 static inline int file_get_write_access(struct file
*f
)
882 error
= get_write_access(f
->f_inode
);
885 error
= mnt_get_write_access(f
->f_path
.mnt
);
888 if (unlikely(f
->f_mode
& FMODE_BACKING
)) {
889 error
= mnt_get_write_access(backing_file_user_path(f
)->mnt
);
896 mnt_put_write_access(f
->f_path
.mnt
);
898 put_write_access(f
->f_inode
);
902 static int do_dentry_open(struct file
*f
,
904 int (*open
)(struct inode
*, struct file
*))
906 static const struct file_operations empty_fops
= {};
909 path_get(&f
->f_path
);
911 f
->f_mapping
= inode
->i_mapping
;
912 f
->f_wb_err
= filemap_sample_wb_err(f
->f_mapping
);
913 f
->f_sb_err
= file_sample_sb_err(f
);
915 if (unlikely(f
->f_flags
& O_PATH
)) {
916 f
->f_mode
= FMODE_PATH
| FMODE_OPENED
;
917 f
->f_op
= &empty_fops
;
921 if ((f
->f_mode
& (FMODE_READ
| FMODE_WRITE
)) == FMODE_READ
) {
922 i_readcount_inc(inode
);
923 } else if (f
->f_mode
& FMODE_WRITE
&& !special_file(inode
->i_mode
)) {
924 error
= file_get_write_access(f
);
927 f
->f_mode
|= FMODE_WRITER
;
930 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
931 if (S_ISREG(inode
->i_mode
) || S_ISDIR(inode
->i_mode
))
932 f
->f_mode
|= FMODE_ATOMIC_POS
;
934 f
->f_op
= fops_get(inode
->i_fop
);
935 if (WARN_ON(!f
->f_op
)) {
940 error
= security_file_open(f
);
944 error
= break_lease(file_inode(f
), f
->f_flags
);
948 /* normally all 3 are set; ->open() can clear them if needed */
949 f
->f_mode
|= FMODE_LSEEK
| FMODE_PREAD
| FMODE_PWRITE
;
951 open
= f
->f_op
->open
;
953 error
= open(inode
, f
);
957 f
->f_mode
|= FMODE_OPENED
;
958 if ((f
->f_mode
& FMODE_READ
) &&
959 likely(f
->f_op
->read
|| f
->f_op
->read_iter
))
960 f
->f_mode
|= FMODE_CAN_READ
;
961 if ((f
->f_mode
& FMODE_WRITE
) &&
962 likely(f
->f_op
->write
|| f
->f_op
->write_iter
))
963 f
->f_mode
|= FMODE_CAN_WRITE
;
964 if ((f
->f_mode
& FMODE_LSEEK
) && !f
->f_op
->llseek
)
965 f
->f_mode
&= ~FMODE_LSEEK
;
966 if (f
->f_mapping
->a_ops
&& f
->f_mapping
->a_ops
->direct_IO
)
967 f
->f_mode
|= FMODE_CAN_ODIRECT
;
969 f
->f_flags
&= ~(O_CREAT
| O_EXCL
| O_NOCTTY
| O_TRUNC
);
970 f
->f_iocb_flags
= iocb_flags(f
);
972 file_ra_state_init(&f
->f_ra
, f
->f_mapping
->host
->i_mapping
);
974 if ((f
->f_flags
& O_DIRECT
) && !(f
->f_mode
& FMODE_CAN_ODIRECT
))
978 * XXX: Huge page cache doesn't support writing yet. Drop all page
979 * cache for this file before processing writes.
981 if (f
->f_mode
& FMODE_WRITE
) {
983 * Paired with smp_mb() in collapse_file() to ensure nr_thps
984 * is up to date and the update to i_writecount by
985 * get_write_access() is visible. Ensures subsequent insertion
986 * of THPs into the page cache will fail.
989 if (filemap_nr_thps(inode
->i_mapping
)) {
990 struct address_space
*mapping
= inode
->i_mapping
;
992 filemap_invalidate_lock(inode
->i_mapping
);
994 * unmap_mapping_range just need to be called once
995 * here, because the private pages is not need to be
996 * unmapped mapping (e.g. data segment of dynamic
997 * shared libraries here).
999 unmap_mapping_range(mapping
, 0, 0, 0);
1000 truncate_inode_pages(mapping
, 0);
1001 filemap_invalidate_unlock(inode
->i_mapping
);
1006 * Once we return a file with FMODE_OPENED, __fput() will call
1007 * fsnotify_close(), so we need fsnotify_open() here for symmetry.
1013 if (WARN_ON_ONCE(error
> 0))
1018 path_put(&f
->f_path
);
1019 f
->f_path
.mnt
= NULL
;
1020 f
->f_path
.dentry
= NULL
;
1026 * finish_open - finish opening a file
1027 * @file: file pointer
1028 * @dentry: pointer to dentry
1029 * @open: open callback
1031 * This can be used to finish opening a file passed to i_op->atomic_open().
1033 * If the open callback is set to NULL, then the standard f_op->open()
1034 * filesystem callback is substituted.
1036 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
1037 * the return value of d_splice_alias(), then the caller needs to perform dput()
1038 * on it after finish_open().
1040 * Returns zero on success or -errno if the open failed.
1042 int finish_open(struct file
*file
, struct dentry
*dentry
,
1043 int (*open
)(struct inode
*, struct file
*))
1045 BUG_ON(file
->f_mode
& FMODE_OPENED
); /* once it's opened, it's opened */
1047 file
->f_path
.dentry
= dentry
;
1048 return do_dentry_open(file
, d_backing_inode(dentry
), open
);
1050 EXPORT_SYMBOL(finish_open
);
1053 * finish_no_open - finish ->atomic_open() without opening the file
1055 * @file: file pointer
1056 * @dentry: dentry or NULL (as returned from ->lookup())
1058 * This can be used to set the result of a successful lookup in ->atomic_open().
1060 * NB: unlike finish_open() this function does consume the dentry reference and
1061 * the caller need not dput() it.
1063 * Returns "0" which must be the return value of ->atomic_open() after having
1064 * called this function.
1066 int finish_no_open(struct file
*file
, struct dentry
*dentry
)
1068 file
->f_path
.dentry
= dentry
;
1071 EXPORT_SYMBOL(finish_no_open
);
1073 char *file_path(struct file
*filp
, char *buf
, int buflen
)
1075 return d_path(&filp
->f_path
, buf
, buflen
);
1077 EXPORT_SYMBOL(file_path
);
1080 * vfs_open - open the file at the given path
1081 * @path: path to open
1082 * @file: newly allocated file with f_flag initialized
1084 int vfs_open(const struct path
*path
, struct file
*file
)
1086 file
->f_path
= *path
;
1087 return do_dentry_open(file
, d_backing_inode(path
->dentry
), NULL
);
1090 struct file
*dentry_open(const struct path
*path
, int flags
,
1091 const struct cred
*cred
)
1096 /* We must always pass in a valid mount pointer. */
1099 f
= alloc_empty_file(flags
, cred
);
1101 error
= vfs_open(path
, f
);
1109 EXPORT_SYMBOL(dentry_open
);
1112 * dentry_create - Create and open a file
1113 * @path: path to create
1115 * @mode: mode bits for new file
1116 * @cred: credentials to use
1118 * Caller must hold the parent directory's lock, and have prepared
1119 * a negative dentry, placed in @path->dentry, for the new file.
1121 * Caller sets @path->mnt to the vfsmount of the filesystem where
1122 * the new file is to be created. The parent directory and the
1123 * negative dentry must reside on the same filesystem instance.
1125 * On success, returns a "struct file *". Otherwise a ERR_PTR
1128 struct file
*dentry_create(const struct path
*path
, int flags
, umode_t mode
,
1129 const struct cred
*cred
)
1134 f
= alloc_empty_file(flags
, cred
);
1138 error
= vfs_create(mnt_idmap(path
->mnt
),
1139 d_inode(path
->dentry
->d_parent
),
1140 path
->dentry
, mode
, true);
1142 error
= vfs_open(path
, f
);
1144 if (unlikely(error
)) {
1146 return ERR_PTR(error
);
1150 EXPORT_SYMBOL(dentry_create
);
1153 * kernel_file_open - open a file for kernel internal use
1154 * @path: path of the file to open
1155 * @flags: open flags
1157 * @cred: credentials for open
1159 * Open a file for use by in-kernel consumers. The file is not accounted
1160 * against nr_files and must not be installed into the file descriptor
1163 * Return: Opened file on success, an error pointer on failure.
1165 struct file
*kernel_file_open(const struct path
*path
, int flags
,
1166 struct inode
*inode
, const struct cred
*cred
)
1171 f
= alloc_empty_file_noaccount(flags
, cred
);
1176 error
= do_dentry_open(f
, inode
, NULL
);
1183 EXPORT_SYMBOL_GPL(kernel_file_open
);
1185 #define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE))
1186 #define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
1188 inline struct open_how
build_open_how(int flags
, umode_t mode
)
1190 struct open_how how
= {
1191 .flags
= flags
& VALID_OPEN_FLAGS
,
1192 .mode
= mode
& S_IALLUGO
,
1195 /* O_PATH beats everything else. */
1196 if (how
.flags
& O_PATH
)
1197 how
.flags
&= O_PATH_FLAGS
;
1198 /* Modes should only be set for create-like flags. */
1199 if (!WILL_CREATE(how
.flags
))
1204 inline int build_open_flags(const struct open_how
*how
, struct open_flags
*op
)
1206 u64 flags
= how
->flags
;
1207 u64 strip
= __FMODE_NONOTIFY
| O_CLOEXEC
;
1208 int lookup_flags
= 0;
1209 int acc_mode
= ACC_MODE(flags
);
1211 BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS
),
1212 "struct open_flags doesn't yet handle flags > 32 bits");
1215 * Strip flags that either shouldn't be set by userspace like
1216 * FMODE_NONOTIFY or that aren't relevant in determining struct
1217 * open_flags like O_CLOEXEC.
1222 * Older syscalls implicitly clear all of the invalid flags or argument
1223 * values before calling build_open_flags(), but openat2(2) checks all
1226 if (flags
& ~VALID_OPEN_FLAGS
)
1228 if (how
->resolve
& ~VALID_RESOLVE_FLAGS
)
1231 /* Scoping flags are mutually exclusive. */
1232 if ((how
->resolve
& RESOLVE_BENEATH
) && (how
->resolve
& RESOLVE_IN_ROOT
))
1235 /* Deal with the mode. */
1236 if (WILL_CREATE(flags
)) {
1237 if (how
->mode
& ~S_IALLUGO
)
1239 op
->mode
= how
->mode
| S_IFREG
;
1247 * Block bugs where O_DIRECTORY | O_CREAT created regular files.
1248 * Note, that blocking O_DIRECTORY | O_CREAT here also protects
1249 * O_TMPFILE below which requires O_DIRECTORY being raised.
1251 if ((flags
& (O_DIRECTORY
| O_CREAT
)) == (O_DIRECTORY
| O_CREAT
))
1254 /* Now handle the creative implementation of O_TMPFILE. */
1255 if (flags
& __O_TMPFILE
) {
1257 * In order to ensure programs get explicit errors when trying
1258 * to use O_TMPFILE on old kernels we enforce that O_DIRECTORY
1259 * is raised alongside __O_TMPFILE.
1261 if (!(flags
& O_DIRECTORY
))
1263 if (!(acc_mode
& MAY_WRITE
))
1266 if (flags
& O_PATH
) {
1267 /* O_PATH only permits certain other flags to be set. */
1268 if (flags
& ~O_PATH_FLAGS
)
1274 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1275 * check for O_DSYNC if the need any syncing at all we enforce it's
1276 * always set instead of having to deal with possibly weird behaviour
1277 * for malicious applications setting only __O_SYNC.
1279 if (flags
& __O_SYNC
)
1282 op
->open_flag
= flags
;
1284 /* O_TRUNC implies we need access checks for write permissions */
1285 if (flags
& O_TRUNC
)
1286 acc_mode
|= MAY_WRITE
;
1288 /* Allow the LSM permission hook to distinguish append
1289 access from general write access. */
1290 if (flags
& O_APPEND
)
1291 acc_mode
|= MAY_APPEND
;
1293 op
->acc_mode
= acc_mode
;
1295 op
->intent
= flags
& O_PATH
? 0 : LOOKUP_OPEN
;
1297 if (flags
& O_CREAT
) {
1298 op
->intent
|= LOOKUP_CREATE
;
1299 if (flags
& O_EXCL
) {
1300 op
->intent
|= LOOKUP_EXCL
;
1301 flags
|= O_NOFOLLOW
;
1305 if (flags
& O_DIRECTORY
)
1306 lookup_flags
|= LOOKUP_DIRECTORY
;
1307 if (!(flags
& O_NOFOLLOW
))
1308 lookup_flags
|= LOOKUP_FOLLOW
;
1310 if (how
->resolve
& RESOLVE_NO_XDEV
)
1311 lookup_flags
|= LOOKUP_NO_XDEV
;
1312 if (how
->resolve
& RESOLVE_NO_MAGICLINKS
)
1313 lookup_flags
|= LOOKUP_NO_MAGICLINKS
;
1314 if (how
->resolve
& RESOLVE_NO_SYMLINKS
)
1315 lookup_flags
|= LOOKUP_NO_SYMLINKS
;
1316 if (how
->resolve
& RESOLVE_BENEATH
)
1317 lookup_flags
|= LOOKUP_BENEATH
;
1318 if (how
->resolve
& RESOLVE_IN_ROOT
)
1319 lookup_flags
|= LOOKUP_IN_ROOT
;
1320 if (how
->resolve
& RESOLVE_CACHED
) {
1321 /* Don't bother even trying for create/truncate/tmpfile open */
1322 if (flags
& (O_TRUNC
| O_CREAT
| __O_TMPFILE
))
1324 lookup_flags
|= LOOKUP_CACHED
;
1327 op
->lookup_flags
= lookup_flags
;
1332 * file_open_name - open file and return file pointer
1334 * @name: struct filename containing path to open
1335 * @flags: open flags as per the open(2) second argument
1336 * @mode: mode for the new file if O_CREAT is set, else ignored
1338 * This is the helper to open a file from kernelspace if you really
1339 * have to. But in generally you should not do this, so please move
1340 * along, nothing to see here..
1342 struct file
*file_open_name(struct filename
*name
, int flags
, umode_t mode
)
1344 struct open_flags op
;
1345 struct open_how how
= build_open_how(flags
, mode
);
1346 int err
= build_open_flags(&how
, &op
);
1348 return ERR_PTR(err
);
1349 return do_filp_open(AT_FDCWD
, name
, &op
);
1353 * filp_open - open file and return file pointer
1355 * @filename: path to open
1356 * @flags: open flags as per the open(2) second argument
1357 * @mode: mode for the new file if O_CREAT is set, else ignored
1359 * This is the helper to open a file from kernelspace if you really
1360 * have to. But in generally you should not do this, so please move
1361 * along, nothing to see here..
1363 struct file
*filp_open(const char *filename
, int flags
, umode_t mode
)
1365 struct filename
*name
= getname_kernel(filename
);
1366 struct file
*file
= ERR_CAST(name
);
1368 if (!IS_ERR(name
)) {
1369 file
= file_open_name(name
, flags
, mode
);
1374 EXPORT_SYMBOL(filp_open
);
1376 struct file
*file_open_root(const struct path
*root
,
1377 const char *filename
, int flags
, umode_t mode
)
1379 struct open_flags op
;
1380 struct open_how how
= build_open_how(flags
, mode
);
1381 int err
= build_open_flags(&how
, &op
);
1383 return ERR_PTR(err
);
1384 return do_file_open_root(root
, filename
, &op
);
1386 EXPORT_SYMBOL(file_open_root
);
1388 static long do_sys_openat2(int dfd
, const char __user
*filename
,
1389 struct open_how
*how
)
1391 struct open_flags op
;
1392 int fd
= build_open_flags(how
, &op
);
1393 struct filename
*tmp
;
1398 tmp
= getname(filename
);
1400 return PTR_ERR(tmp
);
1402 fd
= get_unused_fd_flags(how
->flags
);
1404 struct file
*f
= do_filp_open(dfd
, tmp
, &op
);
1416 long do_sys_open(int dfd
, const char __user
*filename
, int flags
, umode_t mode
)
1418 struct open_how how
= build_open_how(flags
, mode
);
1419 return do_sys_openat2(dfd
, filename
, &how
);
1423 SYSCALL_DEFINE3(open
, const char __user
*, filename
, int, flags
, umode_t
, mode
)
1425 if (force_o_largefile())
1426 flags
|= O_LARGEFILE
;
1427 return do_sys_open(AT_FDCWD
, filename
, flags
, mode
);
1430 SYSCALL_DEFINE4(openat
, int, dfd
, const char __user
*, filename
, int, flags
,
1433 if (force_o_largefile())
1434 flags
|= O_LARGEFILE
;
1435 return do_sys_open(dfd
, filename
, flags
, mode
);
1438 SYSCALL_DEFINE4(openat2
, int, dfd
, const char __user
*, filename
,
1439 struct open_how __user
*, how
, size_t, usize
)
1442 struct open_how tmp
;
1444 BUILD_BUG_ON(sizeof(struct open_how
) < OPEN_HOW_SIZE_VER0
);
1445 BUILD_BUG_ON(sizeof(struct open_how
) != OPEN_HOW_SIZE_LATEST
);
1447 if (unlikely(usize
< OPEN_HOW_SIZE_VER0
))
1450 err
= copy_struct_from_user(&tmp
, sizeof(tmp
), how
, usize
);
1454 audit_openat2_how(&tmp
);
1456 /* O_LARGEFILE is only allowed for non-O_PATH. */
1457 if (!(tmp
.flags
& O_PATH
) && force_o_largefile())
1458 tmp
.flags
|= O_LARGEFILE
;
1460 return do_sys_openat2(dfd
, filename
, &tmp
);
1463 #ifdef CONFIG_COMPAT
1465 * Exactly like sys_open(), except that it doesn't set the
1468 COMPAT_SYSCALL_DEFINE3(open
, const char __user
*, filename
, int, flags
, umode_t
, mode
)
1470 return do_sys_open(AT_FDCWD
, filename
, flags
, mode
);
1474 * Exactly like sys_openat(), except that it doesn't set the
1477 COMPAT_SYSCALL_DEFINE4(openat
, int, dfd
, const char __user
*, filename
, int, flags
, umode_t
, mode
)
1479 return do_sys_open(dfd
, filename
, flags
, mode
);
1486 * For backward compatibility? Maybe this should be moved
1487 * into arch/i386 instead?
1489 SYSCALL_DEFINE2(creat
, const char __user
*, pathname
, umode_t
, mode
)
1491 int flags
= O_CREAT
| O_WRONLY
| O_TRUNC
;
1493 if (force_o_largefile())
1494 flags
|= O_LARGEFILE
;
1495 return do_sys_open(AT_FDCWD
, pathname
, flags
, mode
);
1500 * "id" is the POSIX thread ID. We use the
1501 * files pointer for this..
1503 static int filp_flush(struct file
*filp
, fl_owner_t id
)
1507 if (CHECK_DATA_CORRUPTION(file_count(filp
) == 0,
1508 "VFS: Close: file count is 0 (f_op=%ps)",
1513 if (filp
->f_op
->flush
)
1514 retval
= filp
->f_op
->flush(filp
, id
);
1516 if (likely(!(filp
->f_mode
& FMODE_PATH
))) {
1517 dnotify_flush(filp
, id
);
1518 locks_remove_posix(filp
, id
);
1523 int filp_close(struct file
*filp
, fl_owner_t id
)
1527 retval
= filp_flush(filp
, id
);
1532 EXPORT_SYMBOL(filp_close
);
1535 * Careful here! We test whether the file pointer is NULL before
1536 * releasing the fd. This ensures that one clone task can't release
1537 * an fd while another clone is opening it.
1539 SYSCALL_DEFINE1(close
, unsigned int, fd
)
1544 file
= file_close_fd(fd
);
1548 retval
= filp_flush(file
, current
->files
);
1551 * We're returning to user space. Don't bother
1552 * with any delayed fput() cases.
1556 /* can't restart close syscall because file table entry was cleared */
1557 if (unlikely(retval
== -ERESTARTSYS
||
1558 retval
== -ERESTARTNOINTR
||
1559 retval
== -ERESTARTNOHAND
||
1560 retval
== -ERESTART_RESTARTBLOCK
))
1567 * sys_close_range() - Close all file descriptors in a given range.
1569 * @fd: starting file descriptor to close
1570 * @max_fd: last file descriptor to close
1571 * @flags: reserved for future extensions
1573 * This closes a range of file descriptors. All file descriptors
1574 * from @fd up to and including @max_fd are closed.
1575 * Currently, errors to close a given file descriptor are ignored.
1577 SYSCALL_DEFINE3(close_range
, unsigned int, fd
, unsigned int, max_fd
,
1578 unsigned int, flags
)
1580 return __close_range(fd
, max_fd
, flags
);
1584 * This routine simulates a hangup on the tty, to arrange that users
1585 * are given clean terminals at login time.
1587 SYSCALL_DEFINE0(vhangup
)
1589 if (capable(CAP_SYS_TTY_CONFIG
)) {
1597 * Called when an inode is about to be open.
1598 * We use this to disallow opening large files on 32bit systems if
1599 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1600 * on this flag in sys_open.
1602 int generic_file_open(struct inode
* inode
, struct file
* filp
)
1604 if (!(filp
->f_flags
& O_LARGEFILE
) && i_size_read(inode
) > MAX_NON_LFS
)
1609 EXPORT_SYMBOL(generic_file_open
);
1612 * This is used by subsystems that don't want seekable
1613 * file descriptors. The function is not supposed to ever fail, the only
1614 * reason it returns an 'int' and not 'void' is so that it can be plugged
1615 * directly into file_operations structure.
1617 int nonseekable_open(struct inode
*inode
, struct file
*filp
)
1619 filp
->f_mode
&= ~(FMODE_LSEEK
| FMODE_PREAD
| FMODE_PWRITE
);
1623 EXPORT_SYMBOL(nonseekable_open
);
1626 * stream_open is used by subsystems that want stream-like file descriptors.
1627 * Such file descriptors are not seekable and don't have notion of position
1628 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1629 * Contrary to file descriptors of other regular files, .read() and .write()
1630 * can run simultaneously.
1632 * stream_open never fails and is marked to return int so that it could be
1633 * directly used as file_operations.open .
1635 int stream_open(struct inode
*inode
, struct file
*filp
)
1637 filp
->f_mode
&= ~(FMODE_LSEEK
| FMODE_PREAD
| FMODE_PWRITE
| FMODE_ATOMIC_POS
);
1638 filp
->f_mode
|= FMODE_STREAM
;
1642 EXPORT_SYMBOL(stream_open
);