Staging: wireless drivers Kconfig change
[linux-2.6/mini2440.git] / fs / open.c
blob4f01e06227c69190525944d4a6da07b850715172
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/quotaops.h>
12 #include <linux/fsnotify.h>
13 #include <linux/module.h>
14 #include <linux/slab.h>
15 #include <linux/tty.h>
16 #include <linux/namei.h>
17 #include <linux/backing-dev.h>
18 #include <linux/capability.h>
19 #include <linux/securebits.h>
20 #include <linux/security.h>
21 #include <linux/mount.h>
22 #include <linux/vfs.h>
23 #include <linux/fcntl.h>
24 #include <asm/uaccess.h>
25 #include <linux/fs.h>
26 #include <linux/personality.h>
27 #include <linux/pagemap.h>
28 #include <linux/syscalls.h>
29 #include <linux/rcupdate.h>
30 #include <linux/audit.h>
31 #include <linux/falloc.h>
32 #include <linux/fs_struct.h>
34 int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
36 int retval = -ENODEV;
38 if (dentry) {
39 retval = -ENOSYS;
40 if (dentry->d_sb->s_op->statfs) {
41 memset(buf, 0, sizeof(*buf));
42 retval = security_sb_statfs(dentry);
43 if (retval)
44 return retval;
45 retval = dentry->d_sb->s_op->statfs(dentry, buf);
46 if (retval == 0 && buf->f_frsize == 0)
47 buf->f_frsize = buf->f_bsize;
50 return retval;
53 EXPORT_SYMBOL(vfs_statfs);
55 static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf)
57 struct kstatfs st;
58 int retval;
60 retval = vfs_statfs(dentry, &st);
61 if (retval)
62 return retval;
64 if (sizeof(*buf) == sizeof(st))
65 memcpy(buf, &st, sizeof(st));
66 else {
67 if (sizeof buf->f_blocks == 4) {
68 if ((st.f_blocks | st.f_bfree | st.f_bavail |
69 st.f_bsize | st.f_frsize) &
70 0xffffffff00000000ULL)
71 return -EOVERFLOW;
73 * f_files and f_ffree may be -1; it's okay to stuff
74 * that into 32 bits
76 if (st.f_files != -1 &&
77 (st.f_files & 0xffffffff00000000ULL))
78 return -EOVERFLOW;
79 if (st.f_ffree != -1 &&
80 (st.f_ffree & 0xffffffff00000000ULL))
81 return -EOVERFLOW;
84 buf->f_type = st.f_type;
85 buf->f_bsize = st.f_bsize;
86 buf->f_blocks = st.f_blocks;
87 buf->f_bfree = st.f_bfree;
88 buf->f_bavail = st.f_bavail;
89 buf->f_files = st.f_files;
90 buf->f_ffree = st.f_ffree;
91 buf->f_fsid = st.f_fsid;
92 buf->f_namelen = st.f_namelen;
93 buf->f_frsize = st.f_frsize;
94 memset(buf->f_spare, 0, sizeof(buf->f_spare));
96 return 0;
99 static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf)
101 struct kstatfs st;
102 int retval;
104 retval = vfs_statfs(dentry, &st);
105 if (retval)
106 return retval;
108 if (sizeof(*buf) == sizeof(st))
109 memcpy(buf, &st, sizeof(st));
110 else {
111 buf->f_type = st.f_type;
112 buf->f_bsize = st.f_bsize;
113 buf->f_blocks = st.f_blocks;
114 buf->f_bfree = st.f_bfree;
115 buf->f_bavail = st.f_bavail;
116 buf->f_files = st.f_files;
117 buf->f_ffree = st.f_ffree;
118 buf->f_fsid = st.f_fsid;
119 buf->f_namelen = st.f_namelen;
120 buf->f_frsize = st.f_frsize;
121 memset(buf->f_spare, 0, sizeof(buf->f_spare));
123 return 0;
126 SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
128 struct path path;
129 int error;
131 error = user_path(pathname, &path);
132 if (!error) {
133 struct statfs tmp;
134 error = vfs_statfs_native(path.dentry, &tmp);
135 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
136 error = -EFAULT;
137 path_put(&path);
139 return error;
142 SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
144 struct path path;
145 long error;
147 if (sz != sizeof(*buf))
148 return -EINVAL;
149 error = user_path(pathname, &path);
150 if (!error) {
151 struct statfs64 tmp;
152 error = vfs_statfs64(path.dentry, &tmp);
153 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
154 error = -EFAULT;
155 path_put(&path);
157 return error;
160 SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
162 struct file * file;
163 struct statfs tmp;
164 int error;
166 error = -EBADF;
167 file = fget(fd);
168 if (!file)
169 goto out;
170 error = vfs_statfs_native(file->f_path.dentry, &tmp);
171 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
172 error = -EFAULT;
173 fput(file);
174 out:
175 return error;
178 SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
180 struct file * file;
181 struct statfs64 tmp;
182 int error;
184 if (sz != sizeof(*buf))
185 return -EINVAL;
187 error = -EBADF;
188 file = fget(fd);
189 if (!file)
190 goto out;
191 error = vfs_statfs64(file->f_path.dentry, &tmp);
192 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
193 error = -EFAULT;
194 fput(file);
195 out:
196 return error;
199 int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
200 struct file *filp)
202 int ret;
203 struct iattr newattrs;
205 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
206 if (length < 0)
207 return -EINVAL;
209 newattrs.ia_size = length;
210 newattrs.ia_valid = ATTR_SIZE | time_attrs;
211 if (filp) {
212 newattrs.ia_file = filp;
213 newattrs.ia_valid |= ATTR_FILE;
216 /* Remove suid/sgid on truncate too */
217 ret = should_remove_suid(dentry);
218 if (ret)
219 newattrs.ia_valid |= ret | ATTR_FORCE;
221 mutex_lock(&dentry->d_inode->i_mutex);
222 ret = notify_change(dentry, &newattrs);
223 mutex_unlock(&dentry->d_inode->i_mutex);
224 return ret;
227 static long do_sys_truncate(const char __user *pathname, loff_t length)
229 struct path path;
230 struct inode *inode;
231 int error;
233 error = -EINVAL;
234 if (length < 0) /* sorry, but loff_t says... */
235 goto out;
237 error = user_path(pathname, &path);
238 if (error)
239 goto out;
240 inode = path.dentry->d_inode;
242 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
243 error = -EISDIR;
244 if (S_ISDIR(inode->i_mode))
245 goto dput_and_out;
247 error = -EINVAL;
248 if (!S_ISREG(inode->i_mode))
249 goto dput_and_out;
251 error = mnt_want_write(path.mnt);
252 if (error)
253 goto dput_and_out;
255 error = inode_permission(inode, MAY_WRITE);
256 if (error)
257 goto mnt_drop_write_and_out;
259 error = -EPERM;
260 if (IS_APPEND(inode))
261 goto mnt_drop_write_and_out;
263 error = get_write_access(inode);
264 if (error)
265 goto mnt_drop_write_and_out;
268 * Make sure that there are no leases. get_write_access() protects
269 * against the truncate racing with a lease-granting setlease().
271 error = break_lease(inode, FMODE_WRITE);
272 if (error)
273 goto put_write_and_out;
275 error = locks_verify_truncate(inode, NULL, length);
276 if (!error)
277 error = security_path_truncate(&path, length, 0);
278 if (!error) {
279 vfs_dq_init(inode);
280 error = do_truncate(path.dentry, length, 0, NULL);
283 put_write_and_out:
284 put_write_access(inode);
285 mnt_drop_write_and_out:
286 mnt_drop_write(path.mnt);
287 dput_and_out:
288 path_put(&path);
289 out:
290 return error;
293 SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
295 return do_sys_truncate(path, length);
298 static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
300 struct inode * inode;
301 struct dentry *dentry;
302 struct file * file;
303 int error;
305 error = -EINVAL;
306 if (length < 0)
307 goto out;
308 error = -EBADF;
309 file = fget(fd);
310 if (!file)
311 goto out;
313 /* explicitly opened as large or we are on 64-bit box */
314 if (file->f_flags & O_LARGEFILE)
315 small = 0;
317 dentry = file->f_path.dentry;
318 inode = dentry->d_inode;
319 error = -EINVAL;
320 if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
321 goto out_putf;
323 error = -EINVAL;
324 /* Cannot ftruncate over 2^31 bytes without large file support */
325 if (small && length > MAX_NON_LFS)
326 goto out_putf;
328 error = -EPERM;
329 if (IS_APPEND(inode))
330 goto out_putf;
332 error = locks_verify_truncate(inode, file, length);
333 if (!error)
334 error = security_path_truncate(&file->f_path, length,
335 ATTR_MTIME|ATTR_CTIME);
336 if (!error)
337 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
338 out_putf:
339 fput(file);
340 out:
341 return error;
344 SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
346 long ret = do_sys_ftruncate(fd, length, 1);
347 /* avoid REGPARM breakage on x86: */
348 asmlinkage_protect(2, ret, fd, length);
349 return ret;
352 /* LFS versions of truncate are only needed on 32 bit machines */
353 #if BITS_PER_LONG == 32
354 SYSCALL_DEFINE(truncate64)(const char __user * path, loff_t length)
356 return do_sys_truncate(path, length);
358 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
359 asmlinkage long SyS_truncate64(long path, loff_t length)
361 return SYSC_truncate64((const char __user *) path, length);
363 SYSCALL_ALIAS(sys_truncate64, SyS_truncate64);
364 #endif
366 SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length)
368 long ret = do_sys_ftruncate(fd, length, 0);
369 /* avoid REGPARM breakage on x86: */
370 asmlinkage_protect(2, ret, fd, length);
371 return ret;
373 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
374 asmlinkage long SyS_ftruncate64(long fd, loff_t length)
376 return SYSC_ftruncate64((unsigned int) fd, length);
378 SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64);
379 #endif
380 #endif /* BITS_PER_LONG == 32 */
383 int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
385 struct inode *inode = file->f_path.dentry->d_inode;
386 long ret;
388 if (offset < 0 || len <= 0)
389 return -EINVAL;
391 /* Return error if mode is not supported */
392 if (mode && !(mode & FALLOC_FL_KEEP_SIZE))
393 return -EOPNOTSUPP;
395 if (!(file->f_mode & FMODE_WRITE))
396 return -EBADF;
398 * Revalidate the write permissions, in case security policy has
399 * changed since the files were opened.
401 ret = security_file_permission(file, MAY_WRITE);
402 if (ret)
403 return ret;
405 if (S_ISFIFO(inode->i_mode))
406 return -ESPIPE;
409 * Let individual file system decide if it supports preallocation
410 * for directories or not.
412 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
413 return -ENODEV;
415 /* Check for wrap through zero too */
416 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
417 return -EFBIG;
419 if (!inode->i_op->fallocate)
420 return -EOPNOTSUPP;
422 return inode->i_op->fallocate(inode, mode, offset, len);
425 SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len)
427 struct file *file;
428 int error = -EBADF;
430 file = fget(fd);
431 if (file) {
432 error = do_fallocate(file, mode, offset, len);
433 fput(file);
436 return error;
439 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
440 asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len)
442 return SYSC_fallocate((int)fd, (int)mode, offset, len);
444 SYSCALL_ALIAS(sys_fallocate, SyS_fallocate);
445 #endif
448 * access() needs to use the real uid/gid, not the effective uid/gid.
449 * We do this by temporarily clearing all FS-related capabilities and
450 * switching the fsuid/fsgid around to the real ones.
452 SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
454 const struct cred *old_cred;
455 struct cred *override_cred;
456 struct path path;
457 struct inode *inode;
458 int res;
460 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
461 return -EINVAL;
463 override_cred = prepare_creds();
464 if (!override_cred)
465 return -ENOMEM;
467 override_cred->fsuid = override_cred->uid;
468 override_cred->fsgid = override_cred->gid;
470 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
471 /* Clear the capabilities if we switch to a non-root user */
472 if (override_cred->uid)
473 cap_clear(override_cred->cap_effective);
474 else
475 override_cred->cap_effective =
476 override_cred->cap_permitted;
479 old_cred = override_creds(override_cred);
481 res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
482 if (res)
483 goto out;
485 inode = path.dentry->d_inode;
487 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
489 * MAY_EXEC on regular files is denied if the fs is mounted
490 * with the "noexec" flag.
492 res = -EACCES;
493 if (path.mnt->mnt_flags & MNT_NOEXEC)
494 goto out_path_release;
497 res = inode_permission(inode, mode | MAY_ACCESS);
498 /* SuS v2 requires we report a read only fs too */
499 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
500 goto out_path_release;
502 * This is a rare case where using __mnt_is_readonly()
503 * is OK without a mnt_want/drop_write() pair. Since
504 * no actual write to the fs is performed here, we do
505 * not need to telegraph to that to anyone.
507 * By doing this, we accept that this access is
508 * inherently racy and know that the fs may change
509 * state before we even see this result.
511 if (__mnt_is_readonly(path.mnt))
512 res = -EROFS;
514 out_path_release:
515 path_put(&path);
516 out:
517 revert_creds(old_cred);
518 put_cred(override_cred);
519 return res;
522 SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
524 return sys_faccessat(AT_FDCWD, filename, mode);
527 SYSCALL_DEFINE1(chdir, const char __user *, filename)
529 struct path path;
530 int error;
532 error = user_path_dir(filename, &path);
533 if (error)
534 goto out;
536 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
537 if (error)
538 goto dput_and_out;
540 set_fs_pwd(current->fs, &path);
542 dput_and_out:
543 path_put(&path);
544 out:
545 return error;
548 SYSCALL_DEFINE1(fchdir, unsigned int, fd)
550 struct file *file;
551 struct inode *inode;
552 int error;
554 error = -EBADF;
555 file = fget(fd);
556 if (!file)
557 goto out;
559 inode = file->f_path.dentry->d_inode;
561 error = -ENOTDIR;
562 if (!S_ISDIR(inode->i_mode))
563 goto out_putf;
565 error = inode_permission(inode, MAY_EXEC | MAY_ACCESS);
566 if (!error)
567 set_fs_pwd(current->fs, &file->f_path);
568 out_putf:
569 fput(file);
570 out:
571 return error;
574 SYSCALL_DEFINE1(chroot, const char __user *, filename)
576 struct path path;
577 int error;
579 error = user_path_dir(filename, &path);
580 if (error)
581 goto out;
583 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
584 if (error)
585 goto dput_and_out;
587 error = -EPERM;
588 if (!capable(CAP_SYS_CHROOT))
589 goto dput_and_out;
591 set_fs_root(current->fs, &path);
592 error = 0;
593 dput_and_out:
594 path_put(&path);
595 out:
596 return error;
599 SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode)
601 struct inode * inode;
602 struct dentry * dentry;
603 struct file * file;
604 int err = -EBADF;
605 struct iattr newattrs;
607 file = fget(fd);
608 if (!file)
609 goto out;
611 dentry = file->f_path.dentry;
612 inode = dentry->d_inode;
614 audit_inode(NULL, dentry);
616 err = mnt_want_write_file(file);
617 if (err)
618 goto out_putf;
619 mutex_lock(&inode->i_mutex);
620 if (mode == (mode_t) -1)
621 mode = inode->i_mode;
622 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
623 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
624 err = notify_change(dentry, &newattrs);
625 mutex_unlock(&inode->i_mutex);
626 mnt_drop_write(file->f_path.mnt);
627 out_putf:
628 fput(file);
629 out:
630 return err;
633 SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode)
635 struct path path;
636 struct inode *inode;
637 int error;
638 struct iattr newattrs;
640 error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
641 if (error)
642 goto out;
643 inode = path.dentry->d_inode;
645 error = mnt_want_write(path.mnt);
646 if (error)
647 goto dput_and_out;
648 mutex_lock(&inode->i_mutex);
649 if (mode == (mode_t) -1)
650 mode = inode->i_mode;
651 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
652 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
653 error = notify_change(path.dentry, &newattrs);
654 mutex_unlock(&inode->i_mutex);
655 mnt_drop_write(path.mnt);
656 dput_and_out:
657 path_put(&path);
658 out:
659 return error;
662 SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_t, mode)
664 return sys_fchmodat(AT_FDCWD, filename, mode);
667 static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
669 struct inode *inode = dentry->d_inode;
670 int error;
671 struct iattr newattrs;
673 newattrs.ia_valid = ATTR_CTIME;
674 if (user != (uid_t) -1) {
675 newattrs.ia_valid |= ATTR_UID;
676 newattrs.ia_uid = user;
678 if (group != (gid_t) -1) {
679 newattrs.ia_valid |= ATTR_GID;
680 newattrs.ia_gid = group;
682 if (!S_ISDIR(inode->i_mode))
683 newattrs.ia_valid |=
684 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
685 mutex_lock(&inode->i_mutex);
686 error = notify_change(dentry, &newattrs);
687 mutex_unlock(&inode->i_mutex);
689 return error;
692 SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
694 struct path path;
695 int error;
697 error = user_path(filename, &path);
698 if (error)
699 goto out;
700 error = mnt_want_write(path.mnt);
701 if (error)
702 goto out_release;
703 error = chown_common(path.dentry, user, group);
704 mnt_drop_write(path.mnt);
705 out_release:
706 path_put(&path);
707 out:
708 return error;
711 SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
712 gid_t, group, int, flag)
714 struct path path;
715 int error = -EINVAL;
716 int follow;
718 if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
719 goto out;
721 follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
722 error = user_path_at(dfd, filename, follow, &path);
723 if (error)
724 goto out;
725 error = mnt_want_write(path.mnt);
726 if (error)
727 goto out_release;
728 error = chown_common(path.dentry, user, group);
729 mnt_drop_write(path.mnt);
730 out_release:
731 path_put(&path);
732 out:
733 return error;
736 SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
738 struct path path;
739 int error;
741 error = user_lpath(filename, &path);
742 if (error)
743 goto out;
744 error = mnt_want_write(path.mnt);
745 if (error)
746 goto out_release;
747 error = chown_common(path.dentry, user, group);
748 mnt_drop_write(path.mnt);
749 out_release:
750 path_put(&path);
751 out:
752 return error;
755 SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
757 struct file * file;
758 int error = -EBADF;
759 struct dentry * dentry;
761 file = fget(fd);
762 if (!file)
763 goto out;
765 error = mnt_want_write_file(file);
766 if (error)
767 goto out_fput;
768 dentry = file->f_path.dentry;
769 audit_inode(NULL, dentry);
770 error = chown_common(dentry, user, group);
771 mnt_drop_write(file->f_path.mnt);
772 out_fput:
773 fput(file);
774 out:
775 return error;
779 * You have to be very careful that these write
780 * counts get cleaned up in error cases and
781 * upon __fput(). This should probably never
782 * be called outside of __dentry_open().
784 static inline int __get_file_write_access(struct inode *inode,
785 struct vfsmount *mnt)
787 int error;
788 error = get_write_access(inode);
789 if (error)
790 return error;
792 * Do not take mount writer counts on
793 * special files since no writes to
794 * the mount itself will occur.
796 if (!special_file(inode->i_mode)) {
798 * Balanced in __fput()
800 error = mnt_want_write(mnt);
801 if (error)
802 put_write_access(inode);
804 return error;
807 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
808 int flags, struct file *f,
809 int (*open)(struct inode *, struct file *),
810 const struct cred *cred)
812 struct inode *inode;
813 int error;
815 f->f_flags = flags;
816 f->f_mode = (__force fmode_t)((flags+1) & O_ACCMODE) | FMODE_LSEEK |
817 FMODE_PREAD | FMODE_PWRITE;
818 inode = dentry->d_inode;
819 if (f->f_mode & FMODE_WRITE) {
820 error = __get_file_write_access(inode, mnt);
821 if (error)
822 goto cleanup_file;
823 if (!special_file(inode->i_mode))
824 file_take_write(f);
827 f->f_mapping = inode->i_mapping;
828 f->f_path.dentry = dentry;
829 f->f_path.mnt = mnt;
830 f->f_pos = 0;
831 f->f_op = fops_get(inode->i_fop);
832 file_move(f, &inode->i_sb->s_files);
834 error = security_dentry_open(f, cred);
835 if (error)
836 goto cleanup_all;
838 if (!open && f->f_op)
839 open = f->f_op->open;
840 if (open) {
841 error = open(inode, f);
842 if (error)
843 goto cleanup_all;
846 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
848 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
850 /* NB: we're sure to have correct a_ops only after f_op->open */
851 if (f->f_flags & O_DIRECT) {
852 if (!f->f_mapping->a_ops ||
853 ((!f->f_mapping->a_ops->direct_IO) &&
854 (!f->f_mapping->a_ops->get_xip_mem))) {
855 fput(f);
856 f = ERR_PTR(-EINVAL);
860 return f;
862 cleanup_all:
863 fops_put(f->f_op);
864 if (f->f_mode & FMODE_WRITE) {
865 put_write_access(inode);
866 if (!special_file(inode->i_mode)) {
868 * We don't consider this a real
869 * mnt_want/drop_write() pair
870 * because it all happenend right
871 * here, so just reset the state.
873 file_reset_write(f);
874 mnt_drop_write(mnt);
877 file_kill(f);
878 f->f_path.dentry = NULL;
879 f->f_path.mnt = NULL;
880 cleanup_file:
881 put_filp(f);
882 dput(dentry);
883 mntput(mnt);
884 return ERR_PTR(error);
888 * lookup_instantiate_filp - instantiates the open intent filp
889 * @nd: pointer to nameidata
890 * @dentry: pointer to dentry
891 * @open: open callback
893 * Helper for filesystems that want to use lookup open intents and pass back
894 * a fully instantiated struct file to the caller.
895 * This function is meant to be called from within a filesystem's
896 * lookup method.
897 * Beware of calling it for non-regular files! Those ->open methods might block
898 * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
899 * leading to a deadlock, as nobody can open that fifo anymore, because
900 * another process to open fifo will block on locked parent when doing lookup).
901 * Note that in case of error, nd->intent.open.file is destroyed, but the
902 * path information remains valid.
903 * If the open callback is set to NULL, then the standard f_op->open()
904 * filesystem callback is substituted.
906 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
907 int (*open)(struct inode *, struct file *))
909 const struct cred *cred = current_cred();
911 if (IS_ERR(nd->intent.open.file))
912 goto out;
913 if (IS_ERR(dentry))
914 goto out_err;
915 nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
916 nd->intent.open.flags - 1,
917 nd->intent.open.file,
918 open, cred);
919 out:
920 return nd->intent.open.file;
921 out_err:
922 release_open_intent(nd);
923 nd->intent.open.file = (struct file *)dentry;
924 goto out;
926 EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
929 * nameidata_to_filp - convert a nameidata to an open filp.
930 * @nd: pointer to nameidata
931 * @flags: open flags
933 * Note that this function destroys the original nameidata
935 struct file *nameidata_to_filp(struct nameidata *nd, int flags)
937 const struct cred *cred = current_cred();
938 struct file *filp;
940 /* Pick up the filp from the open intent */
941 filp = nd->intent.open.file;
942 /* Has the filesystem initialised the file for us? */
943 if (filp->f_path.dentry == NULL)
944 filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp,
945 NULL, cred);
946 else
947 path_put(&nd->path);
948 return filp;
952 * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
953 * error.
955 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
956 const struct cred *cred)
958 int error;
959 struct file *f;
961 validate_creds(cred);
964 * We must always pass in a valid mount pointer. Historically
965 * callers got away with not passing it, but we must enforce this at
966 * the earliest possible point now to avoid strange problems deep in the
967 * filesystem stack.
969 if (!mnt) {
970 printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
971 dump_stack();
972 return ERR_PTR(-EINVAL);
975 error = -ENFILE;
976 f = get_empty_filp();
977 if (f == NULL) {
978 dput(dentry);
979 mntput(mnt);
980 return ERR_PTR(error);
983 return __dentry_open(dentry, mnt, flags, f, NULL, cred);
985 EXPORT_SYMBOL(dentry_open);
987 static void __put_unused_fd(struct files_struct *files, unsigned int fd)
989 struct fdtable *fdt = files_fdtable(files);
990 __FD_CLR(fd, fdt->open_fds);
991 if (fd < files->next_fd)
992 files->next_fd = fd;
995 void put_unused_fd(unsigned int fd)
997 struct files_struct *files = current->files;
998 spin_lock(&files->file_lock);
999 __put_unused_fd(files, fd);
1000 spin_unlock(&files->file_lock);
1003 EXPORT_SYMBOL(put_unused_fd);
1006 * Install a file pointer in the fd array.
1008 * The VFS is full of places where we drop the files lock between
1009 * setting the open_fds bitmap and installing the file in the file
1010 * array. At any such point, we are vulnerable to a dup2() race
1011 * installing a file in the array before us. We need to detect this and
1012 * fput() the struct file we are about to overwrite in this case.
1014 * It should never happen - if we allow dup2() do it, _really_ bad things
1015 * will follow.
1018 void fd_install(unsigned int fd, struct file *file)
1020 struct files_struct *files = current->files;
1021 struct fdtable *fdt;
1022 spin_lock(&files->file_lock);
1023 fdt = files_fdtable(files);
1024 BUG_ON(fdt->fd[fd] != NULL);
1025 rcu_assign_pointer(fdt->fd[fd], file);
1026 spin_unlock(&files->file_lock);
1029 EXPORT_SYMBOL(fd_install);
1031 long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
1033 char *tmp = getname(filename);
1034 int fd = PTR_ERR(tmp);
1036 if (!IS_ERR(tmp)) {
1037 fd = get_unused_fd_flags(flags);
1038 if (fd >= 0) {
1039 struct file *f = do_filp_open(dfd, tmp, flags, mode, 0);
1040 if (IS_ERR(f)) {
1041 put_unused_fd(fd);
1042 fd = PTR_ERR(f);
1043 } else {
1044 fsnotify_open(f->f_path.dentry);
1045 fd_install(fd, f);
1048 putname(tmp);
1050 return fd;
1053 SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, mode)
1055 long ret;
1057 if (force_o_largefile())
1058 flags |= O_LARGEFILE;
1060 ret = do_sys_open(AT_FDCWD, filename, flags, mode);
1061 /* avoid REGPARM breakage on x86: */
1062 asmlinkage_protect(3, ret, filename, flags, mode);
1063 return ret;
1066 SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1067 int, mode)
1069 long ret;
1071 if (force_o_largefile())
1072 flags |= O_LARGEFILE;
1074 ret = do_sys_open(dfd, filename, flags, mode);
1075 /* avoid REGPARM breakage on x86: */
1076 asmlinkage_protect(4, ret, dfd, filename, flags, mode);
1077 return ret;
1080 #ifndef __alpha__
1083 * For backward compatibility? Maybe this should be moved
1084 * into arch/i386 instead?
1086 SYSCALL_DEFINE2(creat, const char __user *, pathname, int, mode)
1088 return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1091 #endif
1094 * "id" is the POSIX thread ID. We use the
1095 * files pointer for this..
1097 int filp_close(struct file *filp, fl_owner_t id)
1099 int retval = 0;
1101 if (!file_count(filp)) {
1102 printk(KERN_ERR "VFS: Close: file count is 0\n");
1103 return 0;
1106 if (filp->f_op && filp->f_op->flush)
1107 retval = filp->f_op->flush(filp, id);
1109 dnotify_flush(filp, id);
1110 locks_remove_posix(filp, id);
1111 fput(filp);
1112 return retval;
1115 EXPORT_SYMBOL(filp_close);
1118 * Careful here! We test whether the file pointer is NULL before
1119 * releasing the fd. This ensures that one clone task can't release
1120 * an fd while another clone is opening it.
1122 SYSCALL_DEFINE1(close, unsigned int, fd)
1124 struct file * filp;
1125 struct files_struct *files = current->files;
1126 struct fdtable *fdt;
1127 int retval;
1129 spin_lock(&files->file_lock);
1130 fdt = files_fdtable(files);
1131 if (fd >= fdt->max_fds)
1132 goto out_unlock;
1133 filp = fdt->fd[fd];
1134 if (!filp)
1135 goto out_unlock;
1136 rcu_assign_pointer(fdt->fd[fd], NULL);
1137 FD_CLR(fd, fdt->close_on_exec);
1138 __put_unused_fd(files, fd);
1139 spin_unlock(&files->file_lock);
1140 retval = filp_close(filp, files);
1142 /* can't restart close syscall because file table entry was cleared */
1143 if (unlikely(retval == -ERESTARTSYS ||
1144 retval == -ERESTARTNOINTR ||
1145 retval == -ERESTARTNOHAND ||
1146 retval == -ERESTART_RESTARTBLOCK))
1147 retval = -EINTR;
1149 return retval;
1151 out_unlock:
1152 spin_unlock(&files->file_lock);
1153 return -EBADF;
1155 EXPORT_SYMBOL(sys_close);
1158 * This routine simulates a hangup on the tty, to arrange that users
1159 * are given clean terminals at login time.
1161 SYSCALL_DEFINE0(vhangup)
1163 if (capable(CAP_SYS_TTY_CONFIG)) {
1164 tty_vhangup_self();
1165 return 0;
1167 return -EPERM;
1171 * Called when an inode is about to be open.
1172 * We use this to disallow opening large files on 32bit systems if
1173 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1174 * on this flag in sys_open.
1176 int generic_file_open(struct inode * inode, struct file * filp)
1178 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1179 return -EOVERFLOW;
1180 return 0;
1183 EXPORT_SYMBOL(generic_file_open);
1186 * This is used by subsystems that don't want seekable
1187 * file descriptors
1189 int nonseekable_open(struct inode *inode, struct file *filp)
1191 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1192 return 0;
1195 EXPORT_SYMBOL(nonseekable_open);