Merge branch 'fix/hda' into topic/hda
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / open.c
blobf711921094576c8b46f2aefe50d76da75bfe1c68
1 /*
2 * linux/fs/open.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
7 #include <linux/string.h>
8 #include <linux/mm.h>
9 #include <linux/file.h>
10 #include <linux/fdtable.h>
11 #include <linux/fsnotify.h>
12 #include <linux/module.h>
13 #include <linux/tty.h>
14 #include <linux/namei.h>
15 #include <linux/backing-dev.h>
16 #include <linux/capability.h>
17 #include <linux/securebits.h>
18 #include <linux/security.h>
19 #include <linux/mount.h>
20 #include <linux/fcntl.h>
21 #include <linux/slab.h>
22 #include <asm/uaccess.h>
23 #include <linux/fs.h>
24 #include <linux/personality.h>
25 #include <linux/pagemap.h>
26 #include <linux/syscalls.h>
27 #include <linux/rcupdate.h>
28 #include <linux/audit.h>
29 #include <linux/falloc.h>
30 #include <linux/fs_struct.h>
31 #include <linux/ima.h>
32 #include <linux/dnotify.h>
34 #include "internal.h"
36 int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
37 struct file *filp)
39 int ret;
40 struct iattr newattrs;
42 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
43 if (length < 0)
44 return -EINVAL;
46 newattrs.ia_size = length;
47 newattrs.ia_valid = ATTR_SIZE | time_attrs;
48 if (filp) {
49 newattrs.ia_file = filp;
50 newattrs.ia_valid |= ATTR_FILE;
53 /* Remove suid/sgid on truncate too */
54 ret = should_remove_suid(dentry);
55 if (ret)
56 newattrs.ia_valid |= ret | ATTR_FORCE;
58 mutex_lock(&dentry->d_inode->i_mutex);
59 ret = notify_change(dentry, &newattrs);
60 mutex_unlock(&dentry->d_inode->i_mutex);
61 return ret;
64 static long do_sys_truncate(const char __user *pathname, loff_t length)
66 struct path path;
67 struct inode *inode;
68 int error;
70 error = -EINVAL;
71 if (length < 0) /* sorry, but loff_t says... */
72 goto out;
74 error = user_path(pathname, &path);
75 if (error)
76 goto out;
77 inode = path.dentry->d_inode;
79 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
80 error = -EISDIR;
81 if (S_ISDIR(inode->i_mode))
82 goto dput_and_out;
84 error = -EINVAL;
85 if (!S_ISREG(inode->i_mode))
86 goto dput_and_out;
88 error = mnt_want_write(path.mnt);
89 if (error)
90 goto dput_and_out;
92 error = inode_permission(inode, MAY_WRITE);
93 if (error)
94 goto mnt_drop_write_and_out;
96 error = -EPERM;
97 if (IS_APPEND(inode))
98 goto mnt_drop_write_and_out;
100 error = get_write_access(inode);
101 if (error)
102 goto mnt_drop_write_and_out;
105 * Make sure that there are no leases. get_write_access() protects
106 * against the truncate racing with a lease-granting setlease().
108 error = break_lease(inode, O_WRONLY);
109 if (error)
110 goto put_write_and_out;
112 error = locks_verify_truncate(inode, NULL, length);
113 if (!error)
114 error = security_path_truncate(&path);
115 if (!error)
116 error = do_truncate(path.dentry, length, 0, NULL);
118 put_write_and_out:
119 put_write_access(inode);
120 mnt_drop_write_and_out:
121 mnt_drop_write(path.mnt);
122 dput_and_out:
123 path_put(&path);
124 out:
125 return error;
128 SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
130 return do_sys_truncate(path, length);
133 static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
135 struct inode * inode;
136 struct dentry *dentry;
137 struct file * file;
138 int error;
140 error = -EINVAL;
141 if (length < 0)
142 goto out;
143 error = -EBADF;
144 file = fget(fd);
145 if (!file)
146 goto out;
148 /* explicitly opened as large or we are on 64-bit box */
149 if (file->f_flags & O_LARGEFILE)
150 small = 0;
152 dentry = file->f_path.dentry;
153 inode = dentry->d_inode;
154 error = -EINVAL;
155 if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
156 goto out_putf;
158 error = -EINVAL;
159 /* Cannot ftruncate over 2^31 bytes without large file support */
160 if (small && length > MAX_NON_LFS)
161 goto out_putf;
163 error = -EPERM;
164 if (IS_APPEND(inode))
165 goto out_putf;
167 error = locks_verify_truncate(inode, file, length);
168 if (!error)
169 error = security_path_truncate(&file->f_path);
170 if (!error)
171 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
172 out_putf:
173 fput(file);
174 out:
175 return error;
178 SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
180 long ret = do_sys_ftruncate(fd, length, 1);
181 /* avoid REGPARM breakage on x86: */
182 asmlinkage_protect(2, ret, fd, length);
183 return ret;
186 /* LFS versions of truncate are only needed on 32 bit machines */
187 #if BITS_PER_LONG == 32
188 SYSCALL_DEFINE(truncate64)(const char __user * path, loff_t length)
190 return do_sys_truncate(path, length);
192 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
193 asmlinkage long SyS_truncate64(long path, loff_t length)
195 return SYSC_truncate64((const char __user *) path, length);
197 SYSCALL_ALIAS(sys_truncate64, SyS_truncate64);
198 #endif
200 SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length)
202 long ret = do_sys_ftruncate(fd, length, 0);
203 /* avoid REGPARM breakage on x86: */
204 asmlinkage_protect(2, ret, fd, length);
205 return ret;
207 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
208 asmlinkage long SyS_ftruncate64(long fd, loff_t length)
210 return SYSC_ftruncate64((unsigned int) fd, length);
212 SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64);
213 #endif
214 #endif /* BITS_PER_LONG == 32 */
217 int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
219 struct inode *inode = file->f_path.dentry->d_inode;
220 long ret;
222 if (offset < 0 || len <= 0)
223 return -EINVAL;
225 /* Return error if mode is not supported */
226 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
227 return -EOPNOTSUPP;
229 /* Punch hole must have keep size set */
230 if ((mode & FALLOC_FL_PUNCH_HOLE) &&
231 !(mode & FALLOC_FL_KEEP_SIZE))
232 return -EOPNOTSUPP;
234 if (!(file->f_mode & FMODE_WRITE))
235 return -EBADF;
237 /* It's not possible punch hole on append only file */
238 if (mode & FALLOC_FL_PUNCH_HOLE && IS_APPEND(inode))
239 return -EPERM;
241 if (IS_IMMUTABLE(inode))
242 return -EPERM;
245 * Revalidate the write permissions, in case security policy has
246 * changed since the files were opened.
248 ret = security_file_permission(file, MAY_WRITE);
249 if (ret)
250 return ret;
252 if (S_ISFIFO(inode->i_mode))
253 return -ESPIPE;
256 * Let individual file system decide if it supports preallocation
257 * for directories or not.
259 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
260 return -ENODEV;
262 /* Check for wrap through zero too */
263 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
264 return -EFBIG;
266 if (!file->f_op->fallocate)
267 return -EOPNOTSUPP;
269 return file->f_op->fallocate(file, mode, offset, len);
272 SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len)
274 struct file *file;
275 int error = -EBADF;
277 file = fget(fd);
278 if (file) {
279 error = do_fallocate(file, mode, offset, len);
280 fput(file);
283 return error;
286 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
287 asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len)
289 return SYSC_fallocate((int)fd, (int)mode, offset, len);
291 SYSCALL_ALIAS(sys_fallocate, SyS_fallocate);
292 #endif
295 * access() needs to use the real uid/gid, not the effective uid/gid.
296 * We do this by temporarily clearing all FS-related capabilities and
297 * switching the fsuid/fsgid around to the real ones.
299 SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
301 const struct cred *old_cred;
302 struct cred *override_cred;
303 struct path path;
304 struct inode *inode;
305 int res;
307 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
308 return -EINVAL;
310 override_cred = prepare_creds();
311 if (!override_cred)
312 return -ENOMEM;
314 override_cred->fsuid = override_cred->uid;
315 override_cred->fsgid = override_cred->gid;
317 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
318 /* Clear the capabilities if we switch to a non-root user */
319 if (override_cred->uid)
320 cap_clear(override_cred->cap_effective);
321 else
322 override_cred->cap_effective =
323 override_cred->cap_permitted;
326 old_cred = override_creds(override_cred);
328 res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
329 if (res)
330 goto out;
332 inode = path.dentry->d_inode;
334 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
336 * MAY_EXEC on regular files is denied if the fs is mounted
337 * with the "noexec" flag.
339 res = -EACCES;
340 if (path.mnt->mnt_flags & MNT_NOEXEC)
341 goto out_path_release;
344 res = inode_permission(inode, mode | MAY_ACCESS);
345 /* SuS v2 requires we report a read only fs too */
346 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
347 goto out_path_release;
349 * This is a rare case where using __mnt_is_readonly()
350 * is OK without a mnt_want/drop_write() pair. Since
351 * no actual write to the fs is performed here, we do
352 * not need to telegraph to that to anyone.
354 * By doing this, we accept that this access is
355 * inherently racy and know that the fs may change
356 * state before we even see this result.
358 if (__mnt_is_readonly(path.mnt))
359 res = -EROFS;
361 out_path_release:
362 path_put(&path);
363 out:
364 revert_creds(old_cred);
365 put_cred(override_cred);
366 return res;
369 SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
371 return sys_faccessat(AT_FDCWD, filename, mode);
374 SYSCALL_DEFINE1(chdir, const char __user *, filename)
376 struct path path;
377 int error;
379 error = user_path_dir(filename, &path);
380 if (error)
381 goto out;
383 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
384 if (error)
385 goto dput_and_out;
387 set_fs_pwd(current->fs, &path);
389 dput_and_out:
390 path_put(&path);
391 out:
392 return error;
395 SYSCALL_DEFINE1(fchdir, unsigned int, fd)
397 struct file *file;
398 struct inode *inode;
399 int error;
401 error = -EBADF;
402 file = fget(fd);
403 if (!file)
404 goto out;
406 inode = file->f_path.dentry->d_inode;
408 error = -ENOTDIR;
409 if (!S_ISDIR(inode->i_mode))
410 goto out_putf;
412 error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
413 if (!error)
414 set_fs_pwd(current->fs, &file->f_path);
415 out_putf:
416 fput(file);
417 out:
418 return error;
421 SYSCALL_DEFINE1(chroot, const char __user *, filename)
423 struct path path;
424 int error;
426 error = user_path_dir(filename, &path);
427 if (error)
428 goto out;
430 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
431 if (error)
432 goto dput_and_out;
434 error = -EPERM;
435 if (!capable(CAP_SYS_CHROOT))
436 goto dput_and_out;
437 error = security_path_chroot(&path);
438 if (error)
439 goto dput_and_out;
441 set_fs_root(current->fs, &path);
442 error = 0;
443 dput_and_out:
444 path_put(&path);
445 out:
446 return error;
449 static int chmod_common(struct path *path, umode_t mode)
451 struct inode *inode = path->dentry->d_inode;
452 struct iattr newattrs;
453 int error;
455 error = mnt_want_write(path->mnt);
456 if (error)
457 return error;
458 mutex_lock(&inode->i_mutex);
459 error = security_path_chmod(path->dentry, path->mnt, mode);
460 if (error)
461 goto out_unlock;
462 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
463 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
464 error = notify_change(path->dentry, &newattrs);
465 out_unlock:
466 mutex_unlock(&inode->i_mutex);
467 mnt_drop_write(path->mnt);
468 return error;
471 SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode)
473 struct file * file;
474 int err = -EBADF;
476 file = fget(fd);
477 if (file) {
478 audit_inode(NULL, file->f_path.dentry);
479 err = chmod_common(&file->f_path, mode);
480 fput(file);
482 return err;
485 SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode)
487 struct path path;
488 int error;
490 error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
491 if (!error) {
492 error = chmod_common(&path, mode);
493 path_put(&path);
495 return error;
498 SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_t, mode)
500 return sys_fchmodat(AT_FDCWD, filename, mode);
503 static int chown_common(struct path *path, uid_t user, gid_t group)
505 struct inode *inode = path->dentry->d_inode;
506 int error;
507 struct iattr newattrs;
509 newattrs.ia_valid = ATTR_CTIME;
510 if (user != (uid_t) -1) {
511 newattrs.ia_valid |= ATTR_UID;
512 newattrs.ia_uid = user;
514 if (group != (gid_t) -1) {
515 newattrs.ia_valid |= ATTR_GID;
516 newattrs.ia_gid = group;
518 if (!S_ISDIR(inode->i_mode))
519 newattrs.ia_valid |=
520 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
521 mutex_lock(&inode->i_mutex);
522 error = security_path_chown(path, user, group);
523 if (!error)
524 error = notify_change(path->dentry, &newattrs);
525 mutex_unlock(&inode->i_mutex);
527 return error;
530 SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
532 struct path path;
533 int error;
535 error = user_path(filename, &path);
536 if (error)
537 goto out;
538 error = mnt_want_write(path.mnt);
539 if (error)
540 goto out_release;
541 error = chown_common(&path, user, group);
542 mnt_drop_write(path.mnt);
543 out_release:
544 path_put(&path);
545 out:
546 return error;
549 SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
550 gid_t, group, int, flag)
552 struct path path;
553 int error = -EINVAL;
554 int lookup_flags;
556 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
557 goto out;
559 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
560 if (flag & AT_EMPTY_PATH)
561 lookup_flags |= LOOKUP_EMPTY;
562 error = user_path_at(dfd, filename, lookup_flags, &path);
563 if (error)
564 goto out;
565 error = mnt_want_write(path.mnt);
566 if (error)
567 goto out_release;
568 error = chown_common(&path, user, group);
569 mnt_drop_write(path.mnt);
570 out_release:
571 path_put(&path);
572 out:
573 return error;
576 SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
578 struct path path;
579 int error;
581 error = user_lpath(filename, &path);
582 if (error)
583 goto out;
584 error = mnt_want_write(path.mnt);
585 if (error)
586 goto out_release;
587 error = chown_common(&path, user, group);
588 mnt_drop_write(path.mnt);
589 out_release:
590 path_put(&path);
591 out:
592 return error;
595 SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
597 struct file * file;
598 int error = -EBADF;
599 struct dentry * dentry;
601 file = fget(fd);
602 if (!file)
603 goto out;
605 error = mnt_want_write_file(file);
606 if (error)
607 goto out_fput;
608 dentry = file->f_path.dentry;
609 audit_inode(NULL, dentry);
610 error = chown_common(&file->f_path, user, group);
611 mnt_drop_write(file->f_path.mnt);
612 out_fput:
613 fput(file);
614 out:
615 return error;
619 * You have to be very careful that these write
620 * counts get cleaned up in error cases and
621 * upon __fput(). This should probably never
622 * be called outside of __dentry_open().
624 static inline int __get_file_write_access(struct inode *inode,
625 struct vfsmount *mnt)
627 int error;
628 error = get_write_access(inode);
629 if (error)
630 return error;
632 * Do not take mount writer counts on
633 * special files since no writes to
634 * the mount itself will occur.
636 if (!special_file(inode->i_mode)) {
638 * Balanced in __fput()
640 error = mnt_want_write(mnt);
641 if (error)
642 put_write_access(inode);
644 return error;
647 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
648 struct file *f,
649 int (*open)(struct inode *, struct file *),
650 const struct cred *cred)
652 static const struct file_operations empty_fops = {};
653 struct inode *inode;
654 int error;
656 f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
657 FMODE_PREAD | FMODE_PWRITE;
659 if (unlikely(f->f_flags & O_PATH))
660 f->f_mode = FMODE_PATH;
662 inode = dentry->d_inode;
663 if (f->f_mode & FMODE_WRITE) {
664 error = __get_file_write_access(inode, mnt);
665 if (error)
666 goto cleanup_file;
667 if (!special_file(inode->i_mode))
668 file_take_write(f);
671 f->f_mapping = inode->i_mapping;
672 f->f_path.dentry = dentry;
673 f->f_path.mnt = mnt;
674 f->f_pos = 0;
675 file_sb_list_add(f, inode->i_sb);
677 if (unlikely(f->f_mode & FMODE_PATH)) {
678 f->f_op = &empty_fops;
679 return f;
682 f->f_op = fops_get(inode->i_fop);
684 error = security_dentry_open(f, cred);
685 if (error)
686 goto cleanup_all;
688 if (!open && f->f_op)
689 open = f->f_op->open;
690 if (open) {
691 error = open(inode, f);
692 if (error)
693 goto cleanup_all;
695 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
696 i_readcount_inc(inode);
698 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
700 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
702 /* NB: we're sure to have correct a_ops only after f_op->open */
703 if (f->f_flags & O_DIRECT) {
704 if (!f->f_mapping->a_ops ||
705 ((!f->f_mapping->a_ops->direct_IO) &&
706 (!f->f_mapping->a_ops->get_xip_mem))) {
707 fput(f);
708 f = ERR_PTR(-EINVAL);
712 return f;
714 cleanup_all:
715 fops_put(f->f_op);
716 if (f->f_mode & FMODE_WRITE) {
717 put_write_access(inode);
718 if (!special_file(inode->i_mode)) {
720 * We don't consider this a real
721 * mnt_want/drop_write() pair
722 * because it all happenend right
723 * here, so just reset the state.
725 file_reset_write(f);
726 mnt_drop_write(mnt);
729 file_sb_list_del(f);
730 f->f_path.dentry = NULL;
731 f->f_path.mnt = NULL;
732 cleanup_file:
733 put_filp(f);
734 dput(dentry);
735 mntput(mnt);
736 return ERR_PTR(error);
740 * lookup_instantiate_filp - instantiates the open intent filp
741 * @nd: pointer to nameidata
742 * @dentry: pointer to dentry
743 * @open: open callback
745 * Helper for filesystems that want to use lookup open intents and pass back
746 * a fully instantiated struct file to the caller.
747 * This function is meant to be called from within a filesystem's
748 * lookup method.
749 * Beware of calling it for non-regular files! Those ->open methods might block
750 * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
751 * leading to a deadlock, as nobody can open that fifo anymore, because
752 * another process to open fifo will block on locked parent when doing lookup).
753 * Note that in case of error, nd->intent.open.file is destroyed, but the
754 * path information remains valid.
755 * If the open callback is set to NULL, then the standard f_op->open()
756 * filesystem callback is substituted.
758 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
759 int (*open)(struct inode *, struct file *))
761 const struct cred *cred = current_cred();
763 if (IS_ERR(nd->intent.open.file))
764 goto out;
765 if (IS_ERR(dentry))
766 goto out_err;
767 nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
768 nd->intent.open.file,
769 open, cred);
770 out:
771 return nd->intent.open.file;
772 out_err:
773 release_open_intent(nd);
774 nd->intent.open.file = ERR_CAST(dentry);
775 goto out;
777 EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
780 * nameidata_to_filp - convert a nameidata to an open filp.
781 * @nd: pointer to nameidata
782 * @flags: open flags
784 * Note that this function destroys the original nameidata
786 struct file *nameidata_to_filp(struct nameidata *nd)
788 const struct cred *cred = current_cred();
789 struct file *filp;
791 /* Pick up the filp from the open intent */
792 filp = nd->intent.open.file;
793 nd->intent.open.file = NULL;
795 /* Has the filesystem initialised the file for us? */
796 if (filp->f_path.dentry == NULL) {
797 path_get(&nd->path);
798 filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp,
799 NULL, cred);
801 return filp;
805 * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
806 * error.
808 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
809 const struct cred *cred)
811 int error;
812 struct file *f;
814 validate_creds(cred);
816 /* We must always pass in a valid mount pointer. */
817 BUG_ON(!mnt);
819 error = -ENFILE;
820 f = get_empty_filp();
821 if (f == NULL) {
822 dput(dentry);
823 mntput(mnt);
824 return ERR_PTR(error);
827 f->f_flags = flags;
828 return __dentry_open(dentry, mnt, f, NULL, cred);
830 EXPORT_SYMBOL(dentry_open);
832 static void __put_unused_fd(struct files_struct *files, unsigned int fd)
834 struct fdtable *fdt = files_fdtable(files);
835 __FD_CLR(fd, fdt->open_fds);
836 if (fd < files->next_fd)
837 files->next_fd = fd;
840 void put_unused_fd(unsigned int fd)
842 struct files_struct *files = current->files;
843 spin_lock(&files->file_lock);
844 __put_unused_fd(files, fd);
845 spin_unlock(&files->file_lock);
848 EXPORT_SYMBOL(put_unused_fd);
851 * Install a file pointer in the fd array.
853 * The VFS is full of places where we drop the files lock between
854 * setting the open_fds bitmap and installing the file in the file
855 * array. At any such point, we are vulnerable to a dup2() race
856 * installing a file in the array before us. We need to detect this and
857 * fput() the struct file we are about to overwrite in this case.
859 * It should never happen - if we allow dup2() do it, _really_ bad things
860 * will follow.
863 void fd_install(unsigned int fd, struct file *file)
865 struct files_struct *files = current->files;
866 struct fdtable *fdt;
867 spin_lock(&files->file_lock);
868 fdt = files_fdtable(files);
869 BUG_ON(fdt->fd[fd] != NULL);
870 rcu_assign_pointer(fdt->fd[fd], file);
871 spin_unlock(&files->file_lock);
874 EXPORT_SYMBOL(fd_install);
876 static inline int build_open_flags(int flags, int mode, struct open_flags *op)
878 int lookup_flags = 0;
879 int acc_mode;
881 if (!(flags & O_CREAT))
882 mode = 0;
883 op->mode = mode;
885 /* Must never be set by userspace */
886 flags &= ~FMODE_NONOTIFY;
889 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
890 * check for O_DSYNC if the need any syncing at all we enforce it's
891 * always set instead of having to deal with possibly weird behaviour
892 * for malicious applications setting only __O_SYNC.
894 if (flags & __O_SYNC)
895 flags |= O_DSYNC;
898 * If we have O_PATH in the open flag. Then we
899 * cannot have anything other than the below set of flags
901 if (flags & O_PATH) {
902 flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
903 acc_mode = 0;
904 } else {
905 acc_mode = MAY_OPEN | ACC_MODE(flags);
908 op->open_flag = flags;
910 /* O_TRUNC implies we need access checks for write permissions */
911 if (flags & O_TRUNC)
912 acc_mode |= MAY_WRITE;
914 /* Allow the LSM permission hook to distinguish append
915 access from general write access. */
916 if (flags & O_APPEND)
917 acc_mode |= MAY_APPEND;
919 op->acc_mode = acc_mode;
921 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
923 if (flags & O_CREAT) {
924 op->intent |= LOOKUP_CREATE;
925 if (flags & O_EXCL)
926 op->intent |= LOOKUP_EXCL;
929 if (flags & O_DIRECTORY)
930 lookup_flags |= LOOKUP_DIRECTORY;
931 if (!(flags & O_NOFOLLOW))
932 lookup_flags |= LOOKUP_FOLLOW;
933 return lookup_flags;
937 * filp_open - open file and return file pointer
939 * @filename: path to open
940 * @flags: open flags as per the open(2) second argument
941 * @mode: mode for the new file if O_CREAT is set, else ignored
943 * This is the helper to open a file from kernelspace if you really
944 * have to. But in generally you should not do this, so please move
945 * along, nothing to see here..
947 struct file *filp_open(const char *filename, int flags, int mode)
949 struct open_flags op;
950 int lookup = build_open_flags(flags, mode, &op);
951 return do_filp_open(AT_FDCWD, filename, &op, lookup);
953 EXPORT_SYMBOL(filp_open);
955 struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
956 const char *filename, int flags)
958 struct open_flags op;
959 int lookup = build_open_flags(flags, 0, &op);
960 if (flags & O_CREAT)
961 return ERR_PTR(-EINVAL);
962 if (!filename && (flags & O_DIRECTORY))
963 if (!dentry->d_inode->i_op->lookup)
964 return ERR_PTR(-ENOTDIR);
965 return do_file_open_root(dentry, mnt, filename, &op, lookup);
967 EXPORT_SYMBOL(file_open_root);
969 long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
971 struct open_flags op;
972 int lookup = build_open_flags(flags, mode, &op);
973 char *tmp = getname(filename);
974 int fd = PTR_ERR(tmp);
976 if (!IS_ERR(tmp)) {
977 fd = get_unused_fd_flags(flags);
978 if (fd >= 0) {
979 struct file *f = do_filp_open(dfd, tmp, &op, lookup);
980 if (IS_ERR(f)) {
981 put_unused_fd(fd);
982 fd = PTR_ERR(f);
983 } else {
984 fsnotify_open(f);
985 fd_install(fd, f);
988 putname(tmp);
990 return fd;
993 SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, mode)
995 long ret;
997 if (force_o_largefile())
998 flags |= O_LARGEFILE;
1000 ret = do_sys_open(AT_FDCWD, filename, flags, mode);
1001 /* avoid REGPARM breakage on x86: */
1002 asmlinkage_protect(3, ret, filename, flags, mode);
1003 return ret;
1006 SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1007 int, mode)
1009 long ret;
1011 if (force_o_largefile())
1012 flags |= O_LARGEFILE;
1014 ret = do_sys_open(dfd, filename, flags, mode);
1015 /* avoid REGPARM breakage on x86: */
1016 asmlinkage_protect(4, ret, dfd, filename, flags, mode);
1017 return ret;
1020 #ifndef __alpha__
1023 * For backward compatibility? Maybe this should be moved
1024 * into arch/i386 instead?
1026 SYSCALL_DEFINE2(creat, const char __user *, pathname, int, mode)
1028 return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1031 #endif
1034 * "id" is the POSIX thread ID. We use the
1035 * files pointer for this..
1037 int filp_close(struct file *filp, fl_owner_t id)
1039 int retval = 0;
1041 if (!file_count(filp)) {
1042 printk(KERN_ERR "VFS: Close: file count is 0\n");
1043 return 0;
1046 if (filp->f_op && filp->f_op->flush)
1047 retval = filp->f_op->flush(filp, id);
1049 if (likely(!(filp->f_mode & FMODE_PATH))) {
1050 dnotify_flush(filp, id);
1051 locks_remove_posix(filp, id);
1053 fput(filp);
1054 return retval;
1057 EXPORT_SYMBOL(filp_close);
1060 * Careful here! We test whether the file pointer is NULL before
1061 * releasing the fd. This ensures that one clone task can't release
1062 * an fd while another clone is opening it.
1064 SYSCALL_DEFINE1(close, unsigned int, fd)
1066 struct file * filp;
1067 struct files_struct *files = current->files;
1068 struct fdtable *fdt;
1069 int retval;
1071 spin_lock(&files->file_lock);
1072 fdt = files_fdtable(files);
1073 if (fd >= fdt->max_fds)
1074 goto out_unlock;
1075 filp = fdt->fd[fd];
1076 if (!filp)
1077 goto out_unlock;
1078 rcu_assign_pointer(fdt->fd[fd], NULL);
1079 FD_CLR(fd, fdt->close_on_exec);
1080 __put_unused_fd(files, fd);
1081 spin_unlock(&files->file_lock);
1082 retval = filp_close(filp, files);
1084 /* can't restart close syscall because file table entry was cleared */
1085 if (unlikely(retval == -ERESTARTSYS ||
1086 retval == -ERESTARTNOINTR ||
1087 retval == -ERESTARTNOHAND ||
1088 retval == -ERESTART_RESTARTBLOCK))
1089 retval = -EINTR;
1091 return retval;
1093 out_unlock:
1094 spin_unlock(&files->file_lock);
1095 return -EBADF;
1097 EXPORT_SYMBOL(sys_close);
1100 * This routine simulates a hangup on the tty, to arrange that users
1101 * are given clean terminals at login time.
1103 SYSCALL_DEFINE0(vhangup)
1105 if (capable(CAP_SYS_TTY_CONFIG)) {
1106 tty_vhangup_self();
1107 return 0;
1109 return -EPERM;
1113 * Called when an inode is about to be open.
1114 * We use this to disallow opening large files on 32bit systems if
1115 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1116 * on this flag in sys_open.
1118 int generic_file_open(struct inode * inode, struct file * filp)
1120 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1121 return -EOVERFLOW;
1122 return 0;
1125 EXPORT_SYMBOL(generic_file_open);
1128 * This is used by subsystems that don't want seekable
1129 * file descriptors. The function is not supposed to ever fail, the only
1130 * reason it returns an 'int' and not 'void' is so that it can be plugged
1131 * directly into file_operations structure.
1133 int nonseekable_open(struct inode *inode, struct file *filp)
1135 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1136 return 0;
1139 EXPORT_SYMBOL(nonseekable_open);