nfsd: nfsd should drop CAP_MKNOD for non-root
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / open.c
bloba3a78ceb2a2bf8c52a3b16cb7e5ca5648f710b15
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>
33 int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
35 int retval = -ENODEV;
37 if (dentry) {
38 retval = -ENOSYS;
39 if (dentry->d_sb->s_op->statfs) {
40 memset(buf, 0, sizeof(*buf));
41 retval = security_sb_statfs(dentry);
42 if (retval)
43 return retval;
44 retval = dentry->d_sb->s_op->statfs(dentry, buf);
45 if (retval == 0 && buf->f_frsize == 0)
46 buf->f_frsize = buf->f_bsize;
49 return retval;
52 EXPORT_SYMBOL(vfs_statfs);
54 static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf)
56 struct kstatfs st;
57 int retval;
59 retval = vfs_statfs(dentry, &st);
60 if (retval)
61 return retval;
63 if (sizeof(*buf) == sizeof(st))
64 memcpy(buf, &st, sizeof(st));
65 else {
66 if (sizeof buf->f_blocks == 4) {
67 if ((st.f_blocks | st.f_bfree | st.f_bavail |
68 st.f_bsize | st.f_frsize) &
69 0xffffffff00000000ULL)
70 return -EOVERFLOW;
72 * f_files and f_ffree may be -1; it's okay to stuff
73 * that into 32 bits
75 if (st.f_files != -1 &&
76 (st.f_files & 0xffffffff00000000ULL))
77 return -EOVERFLOW;
78 if (st.f_ffree != -1 &&
79 (st.f_ffree & 0xffffffff00000000ULL))
80 return -EOVERFLOW;
83 buf->f_type = st.f_type;
84 buf->f_bsize = st.f_bsize;
85 buf->f_blocks = st.f_blocks;
86 buf->f_bfree = st.f_bfree;
87 buf->f_bavail = st.f_bavail;
88 buf->f_files = st.f_files;
89 buf->f_ffree = st.f_ffree;
90 buf->f_fsid = st.f_fsid;
91 buf->f_namelen = st.f_namelen;
92 buf->f_frsize = st.f_frsize;
93 memset(buf->f_spare, 0, sizeof(buf->f_spare));
95 return 0;
98 static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf)
100 struct kstatfs st;
101 int retval;
103 retval = vfs_statfs(dentry, &st);
104 if (retval)
105 return retval;
107 if (sizeof(*buf) == sizeof(st))
108 memcpy(buf, &st, sizeof(st));
109 else {
110 buf->f_type = st.f_type;
111 buf->f_bsize = st.f_bsize;
112 buf->f_blocks = st.f_blocks;
113 buf->f_bfree = st.f_bfree;
114 buf->f_bavail = st.f_bavail;
115 buf->f_files = st.f_files;
116 buf->f_ffree = st.f_ffree;
117 buf->f_fsid = st.f_fsid;
118 buf->f_namelen = st.f_namelen;
119 buf->f_frsize = st.f_frsize;
120 memset(buf->f_spare, 0, sizeof(buf->f_spare));
122 return 0;
125 SYSCALL_DEFINE2(statfs, const char __user *, pathname, struct statfs __user *, buf)
127 struct path path;
128 int error;
130 error = user_path(pathname, &path);
131 if (!error) {
132 struct statfs tmp;
133 error = vfs_statfs_native(path.dentry, &tmp);
134 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
135 error = -EFAULT;
136 path_put(&path);
138 return error;
141 SYSCALL_DEFINE3(statfs64, const char __user *, pathname, size_t, sz, struct statfs64 __user *, buf)
143 struct path path;
144 long error;
146 if (sz != sizeof(*buf))
147 return -EINVAL;
148 error = user_path(pathname, &path);
149 if (!error) {
150 struct statfs64 tmp;
151 error = vfs_statfs64(path.dentry, &tmp);
152 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
153 error = -EFAULT;
154 path_put(&path);
156 return error;
159 SYSCALL_DEFINE2(fstatfs, unsigned int, fd, struct statfs __user *, buf)
161 struct file * file;
162 struct statfs tmp;
163 int error;
165 error = -EBADF;
166 file = fget(fd);
167 if (!file)
168 goto out;
169 error = vfs_statfs_native(file->f_path.dentry, &tmp);
170 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
171 error = -EFAULT;
172 fput(file);
173 out:
174 return error;
177 SYSCALL_DEFINE3(fstatfs64, unsigned int, fd, size_t, sz, struct statfs64 __user *, buf)
179 struct file * file;
180 struct statfs64 tmp;
181 int error;
183 if (sz != sizeof(*buf))
184 return -EINVAL;
186 error = -EBADF;
187 file = fget(fd);
188 if (!file)
189 goto out;
190 error = vfs_statfs64(file->f_path.dentry, &tmp);
191 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
192 error = -EFAULT;
193 fput(file);
194 out:
195 return error;
198 int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
199 struct file *filp)
201 int err;
202 struct iattr newattrs;
204 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
205 if (length < 0)
206 return -EINVAL;
208 newattrs.ia_size = length;
209 newattrs.ia_valid = ATTR_SIZE | time_attrs;
210 if (filp) {
211 newattrs.ia_file = filp;
212 newattrs.ia_valid |= ATTR_FILE;
215 /* Remove suid/sgid on truncate too */
216 newattrs.ia_valid |= should_remove_suid(dentry);
218 mutex_lock(&dentry->d_inode->i_mutex);
219 err = notify_change(dentry, &newattrs);
220 mutex_unlock(&dentry->d_inode->i_mutex);
221 return err;
224 static long do_sys_truncate(const char __user *pathname, loff_t length)
226 struct path path;
227 struct inode *inode;
228 int error;
230 error = -EINVAL;
231 if (length < 0) /* sorry, but loff_t says... */
232 goto out;
234 error = user_path(pathname, &path);
235 if (error)
236 goto out;
237 inode = path.dentry->d_inode;
239 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
240 error = -EISDIR;
241 if (S_ISDIR(inode->i_mode))
242 goto dput_and_out;
244 error = -EINVAL;
245 if (!S_ISREG(inode->i_mode))
246 goto dput_and_out;
248 error = mnt_want_write(path.mnt);
249 if (error)
250 goto dput_and_out;
252 error = inode_permission(inode, MAY_WRITE);
253 if (error)
254 goto mnt_drop_write_and_out;
256 error = -EPERM;
257 if (IS_APPEND(inode))
258 goto mnt_drop_write_and_out;
260 error = get_write_access(inode);
261 if (error)
262 goto mnt_drop_write_and_out;
265 * Make sure that there are no leases. get_write_access() protects
266 * against the truncate racing with a lease-granting setlease().
268 error = break_lease(inode, FMODE_WRITE);
269 if (error)
270 goto put_write_and_out;
272 error = locks_verify_truncate(inode, NULL, length);
273 if (!error)
274 error = security_path_truncate(&path, length, 0);
275 if (!error) {
276 DQUOT_INIT(inode);
277 error = do_truncate(path.dentry, length, 0, NULL);
280 put_write_and_out:
281 put_write_access(inode);
282 mnt_drop_write_and_out:
283 mnt_drop_write(path.mnt);
284 dput_and_out:
285 path_put(&path);
286 out:
287 return error;
290 SYSCALL_DEFINE2(truncate, const char __user *, path, unsigned long, length)
292 /* on 32-bit boxen it will cut the range 2^31--2^32-1 off */
293 return do_sys_truncate(path, (long)length);
296 static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
298 struct inode * inode;
299 struct dentry *dentry;
300 struct file * file;
301 int error;
303 error = -EINVAL;
304 if (length < 0)
305 goto out;
306 error = -EBADF;
307 file = fget(fd);
308 if (!file)
309 goto out;
311 /* explicitly opened as large or we are on 64-bit box */
312 if (file->f_flags & O_LARGEFILE)
313 small = 0;
315 dentry = file->f_path.dentry;
316 inode = dentry->d_inode;
317 error = -EINVAL;
318 if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
319 goto out_putf;
321 error = -EINVAL;
322 /* Cannot ftruncate over 2^31 bytes without large file support */
323 if (small && length > MAX_NON_LFS)
324 goto out_putf;
326 error = -EPERM;
327 if (IS_APPEND(inode))
328 goto out_putf;
330 error = locks_verify_truncate(inode, file, length);
331 if (!error)
332 error = security_path_truncate(&file->f_path, length,
333 ATTR_MTIME|ATTR_CTIME);
334 if (!error)
335 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
336 out_putf:
337 fput(file);
338 out:
339 return error;
342 SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
344 long ret = do_sys_ftruncate(fd, length, 1);
345 /* avoid REGPARM breakage on x86: */
346 asmlinkage_protect(2, ret, fd, length);
347 return ret;
350 /* LFS versions of truncate are only needed on 32 bit machines */
351 #if BITS_PER_LONG == 32
352 SYSCALL_DEFINE(truncate64)(const char __user * path, loff_t length)
354 return do_sys_truncate(path, length);
356 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
357 asmlinkage long SyS_truncate64(long path, loff_t length)
359 return SYSC_truncate64((const char __user *) path, length);
361 SYSCALL_ALIAS(sys_truncate64, SyS_truncate64);
362 #endif
364 SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length)
366 long ret = do_sys_ftruncate(fd, length, 0);
367 /* avoid REGPARM breakage on x86: */
368 asmlinkage_protect(2, ret, fd, length);
369 return ret;
371 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
372 asmlinkage long SyS_ftruncate64(long fd, loff_t length)
374 return SYSC_ftruncate64((unsigned int) fd, length);
376 SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64);
377 #endif
378 #endif /* BITS_PER_LONG == 32 */
380 SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len)
382 struct file *file;
383 struct inode *inode;
384 long ret = -EINVAL;
386 if (offset < 0 || len <= 0)
387 goto out;
389 /* Return error if mode is not supported */
390 ret = -EOPNOTSUPP;
391 if (mode && !(mode & FALLOC_FL_KEEP_SIZE))
392 goto out;
394 ret = -EBADF;
395 file = fget(fd);
396 if (!file)
397 goto out;
398 if (!(file->f_mode & FMODE_WRITE))
399 goto out_fput;
401 * Revalidate the write permissions, in case security policy has
402 * changed since the files were opened.
404 ret = security_file_permission(file, MAY_WRITE);
405 if (ret)
406 goto out_fput;
408 inode = file->f_path.dentry->d_inode;
410 ret = -ESPIPE;
411 if (S_ISFIFO(inode->i_mode))
412 goto out_fput;
414 ret = -ENODEV;
416 * Let individual file system decide if it supports preallocation
417 * for directories or not.
419 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
420 goto out_fput;
422 ret = -EFBIG;
423 /* Check for wrap through zero too */
424 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
425 goto out_fput;
427 if (inode->i_op->fallocate)
428 ret = inode->i_op->fallocate(inode, mode, offset, len);
429 else
430 ret = -EOPNOTSUPP;
432 out_fput:
433 fput(file);
434 out:
435 return ret;
437 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
438 asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len)
440 return SYSC_fallocate((int)fd, (int)mode, offset, len);
442 SYSCALL_ALIAS(sys_fallocate, SyS_fallocate);
443 #endif
446 * access() needs to use the real uid/gid, not the effective uid/gid.
447 * We do this by temporarily clearing all FS-related capabilities and
448 * switching the fsuid/fsgid around to the real ones.
450 SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
452 const struct cred *old_cred;
453 struct cred *override_cred;
454 struct path path;
455 struct inode *inode;
456 int res;
458 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
459 return -EINVAL;
461 override_cred = prepare_creds();
462 if (!override_cred)
463 return -ENOMEM;
465 override_cred->fsuid = override_cred->uid;
466 override_cred->fsgid = override_cred->gid;
468 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
469 /* Clear the capabilities if we switch to a non-root user */
470 if (override_cred->uid)
471 cap_clear(override_cred->cap_effective);
472 else
473 override_cred->cap_effective =
474 override_cred->cap_permitted;
477 old_cred = override_creds(override_cred);
479 res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
480 if (res)
481 goto out;
483 inode = path.dentry->d_inode;
485 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
487 * MAY_EXEC on regular files is denied if the fs is mounted
488 * with the "noexec" flag.
490 res = -EACCES;
491 if (path.mnt->mnt_flags & MNT_NOEXEC)
492 goto out_path_release;
495 res = inode_permission(inode, mode | MAY_ACCESS);
496 /* SuS v2 requires we report a read only fs too */
497 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
498 goto out_path_release;
500 * This is a rare case where using __mnt_is_readonly()
501 * is OK without a mnt_want/drop_write() pair. Since
502 * no actual write to the fs is performed here, we do
503 * not need to telegraph to that to anyone.
505 * By doing this, we accept that this access is
506 * inherently racy and know that the fs may change
507 * state before we even see this result.
509 if (__mnt_is_readonly(path.mnt))
510 res = -EROFS;
512 out_path_release:
513 path_put(&path);
514 out:
515 revert_creds(old_cred);
516 put_cred(override_cred);
517 return res;
520 SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
522 return sys_faccessat(AT_FDCWD, filename, mode);
525 SYSCALL_DEFINE1(chdir, const char __user *, filename)
527 struct path path;
528 int error;
530 error = user_path_dir(filename, &path);
531 if (error)
532 goto out;
534 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
535 if (error)
536 goto dput_and_out;
538 set_fs_pwd(current->fs, &path);
540 dput_and_out:
541 path_put(&path);
542 out:
543 return error;
546 SYSCALL_DEFINE1(fchdir, unsigned int, fd)
548 struct file *file;
549 struct inode *inode;
550 int error;
552 error = -EBADF;
553 file = fget(fd);
554 if (!file)
555 goto out;
557 inode = file->f_path.dentry->d_inode;
559 error = -ENOTDIR;
560 if (!S_ISDIR(inode->i_mode))
561 goto out_putf;
563 error = inode_permission(inode, MAY_EXEC | MAY_ACCESS);
564 if (!error)
565 set_fs_pwd(current->fs, &file->f_path);
566 out_putf:
567 fput(file);
568 out:
569 return error;
572 SYSCALL_DEFINE1(chroot, const char __user *, filename)
574 struct path path;
575 int error;
577 error = user_path_dir(filename, &path);
578 if (error)
579 goto out;
581 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_ACCESS);
582 if (error)
583 goto dput_and_out;
585 error = -EPERM;
586 if (!capable(CAP_SYS_CHROOT))
587 goto dput_and_out;
589 set_fs_root(current->fs, &path);
590 error = 0;
591 dput_and_out:
592 path_put(&path);
593 out:
594 return error;
597 SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode)
599 struct inode * inode;
600 struct dentry * dentry;
601 struct file * file;
602 int err = -EBADF;
603 struct iattr newattrs;
605 file = fget(fd);
606 if (!file)
607 goto out;
609 dentry = file->f_path.dentry;
610 inode = dentry->d_inode;
612 audit_inode(NULL, dentry);
614 err = mnt_want_write(file->f_path.mnt);
615 if (err)
616 goto out_putf;
617 mutex_lock(&inode->i_mutex);
618 if (mode == (mode_t) -1)
619 mode = inode->i_mode;
620 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
621 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
622 err = notify_change(dentry, &newattrs);
623 mutex_unlock(&inode->i_mutex);
624 mnt_drop_write(file->f_path.mnt);
625 out_putf:
626 fput(file);
627 out:
628 return err;
631 SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode)
633 struct path path;
634 struct inode *inode;
635 int error;
636 struct iattr newattrs;
638 error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path);
639 if (error)
640 goto out;
641 inode = path.dentry->d_inode;
643 error = mnt_want_write(path.mnt);
644 if (error)
645 goto dput_and_out;
646 mutex_lock(&inode->i_mutex);
647 if (mode == (mode_t) -1)
648 mode = inode->i_mode;
649 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
650 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
651 error = notify_change(path.dentry, &newattrs);
652 mutex_unlock(&inode->i_mutex);
653 mnt_drop_write(path.mnt);
654 dput_and_out:
655 path_put(&path);
656 out:
657 return error;
660 SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_t, mode)
662 return sys_fchmodat(AT_FDCWD, filename, mode);
665 static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
667 struct inode *inode = dentry->d_inode;
668 int error;
669 struct iattr newattrs;
671 newattrs.ia_valid = ATTR_CTIME;
672 if (user != (uid_t) -1) {
673 newattrs.ia_valid |= ATTR_UID;
674 newattrs.ia_uid = user;
676 if (group != (gid_t) -1) {
677 newattrs.ia_valid |= ATTR_GID;
678 newattrs.ia_gid = group;
680 if (!S_ISDIR(inode->i_mode))
681 newattrs.ia_valid |=
682 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
683 mutex_lock(&inode->i_mutex);
684 error = notify_change(dentry, &newattrs);
685 mutex_unlock(&inode->i_mutex);
687 return error;
690 SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
692 struct path path;
693 int error;
695 error = user_path(filename, &path);
696 if (error)
697 goto out;
698 error = mnt_want_write(path.mnt);
699 if (error)
700 goto out_release;
701 error = chown_common(path.dentry, user, group);
702 mnt_drop_write(path.mnt);
703 out_release:
704 path_put(&path);
705 out:
706 return error;
709 SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
710 gid_t, group, int, flag)
712 struct path path;
713 int error = -EINVAL;
714 int follow;
716 if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
717 goto out;
719 follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
720 error = user_path_at(dfd, filename, follow, &path);
721 if (error)
722 goto out;
723 error = mnt_want_write(path.mnt);
724 if (error)
725 goto out_release;
726 error = chown_common(path.dentry, user, group);
727 mnt_drop_write(path.mnt);
728 out_release:
729 path_put(&path);
730 out:
731 return error;
734 SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
736 struct path path;
737 int error;
739 error = user_lpath(filename, &path);
740 if (error)
741 goto out;
742 error = mnt_want_write(path.mnt);
743 if (error)
744 goto out_release;
745 error = chown_common(path.dentry, user, group);
746 mnt_drop_write(path.mnt);
747 out_release:
748 path_put(&path);
749 out:
750 return error;
753 SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
755 struct file * file;
756 int error = -EBADF;
757 struct dentry * dentry;
759 file = fget(fd);
760 if (!file)
761 goto out;
763 error = mnt_want_write(file->f_path.mnt);
764 if (error)
765 goto out_fput;
766 dentry = file->f_path.dentry;
767 audit_inode(NULL, dentry);
768 error = chown_common(dentry, user, group);
769 mnt_drop_write(file->f_path.mnt);
770 out_fput:
771 fput(file);
772 out:
773 return error;
777 * You have to be very careful that these write
778 * counts get cleaned up in error cases and
779 * upon __fput(). This should probably never
780 * be called outside of __dentry_open().
782 static inline int __get_file_write_access(struct inode *inode,
783 struct vfsmount *mnt)
785 int error;
786 error = get_write_access(inode);
787 if (error)
788 return error;
790 * Do not take mount writer counts on
791 * special files since no writes to
792 * the mount itself will occur.
794 if (!special_file(inode->i_mode)) {
796 * Balanced in __fput()
798 error = mnt_want_write(mnt);
799 if (error)
800 put_write_access(inode);
802 return error;
805 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
806 int flags, struct file *f,
807 int (*open)(struct inode *, struct file *),
808 const struct cred *cred)
810 struct inode *inode;
811 int error;
813 f->f_flags = flags;
814 f->f_mode = (__force fmode_t)((flags+1) & O_ACCMODE) | FMODE_LSEEK |
815 FMODE_PREAD | FMODE_PWRITE;
816 inode = dentry->d_inode;
817 if (f->f_mode & FMODE_WRITE) {
818 error = __get_file_write_access(inode, mnt);
819 if (error)
820 goto cleanup_file;
821 if (!special_file(inode->i_mode))
822 file_take_write(f);
825 f->f_mapping = inode->i_mapping;
826 f->f_path.dentry = dentry;
827 f->f_path.mnt = mnt;
828 f->f_pos = 0;
829 f->f_op = fops_get(inode->i_fop);
830 file_move(f, &inode->i_sb->s_files);
832 error = security_dentry_open(f, cred);
833 if (error)
834 goto cleanup_all;
836 if (!open && f->f_op)
837 open = f->f_op->open;
838 if (open) {
839 error = open(inode, f);
840 if (error)
841 goto cleanup_all;
844 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
846 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
848 /* NB: we're sure to have correct a_ops only after f_op->open */
849 if (f->f_flags & O_DIRECT) {
850 if (!f->f_mapping->a_ops ||
851 ((!f->f_mapping->a_ops->direct_IO) &&
852 (!f->f_mapping->a_ops->get_xip_mem))) {
853 fput(f);
854 f = ERR_PTR(-EINVAL);
858 return f;
860 cleanup_all:
861 fops_put(f->f_op);
862 if (f->f_mode & FMODE_WRITE) {
863 put_write_access(inode);
864 if (!special_file(inode->i_mode)) {
866 * We don't consider this a real
867 * mnt_want/drop_write() pair
868 * because it all happenend right
869 * here, so just reset the state.
871 file_reset_write(f);
872 mnt_drop_write(mnt);
875 file_kill(f);
876 f->f_path.dentry = NULL;
877 f->f_path.mnt = NULL;
878 cleanup_file:
879 put_filp(f);
880 dput(dentry);
881 mntput(mnt);
882 return ERR_PTR(error);
886 * lookup_instantiate_filp - instantiates the open intent filp
887 * @nd: pointer to nameidata
888 * @dentry: pointer to dentry
889 * @open: open callback
891 * Helper for filesystems that want to use lookup open intents and pass back
892 * a fully instantiated struct file to the caller.
893 * This function is meant to be called from within a filesystem's
894 * lookup method.
895 * Beware of calling it for non-regular files! Those ->open methods might block
896 * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
897 * leading to a deadlock, as nobody can open that fifo anymore, because
898 * another process to open fifo will block on locked parent when doing lookup).
899 * Note that in case of error, nd->intent.open.file is destroyed, but the
900 * path information remains valid.
901 * If the open callback is set to NULL, then the standard f_op->open()
902 * filesystem callback is substituted.
904 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
905 int (*open)(struct inode *, struct file *))
907 const struct cred *cred = current_cred();
909 if (IS_ERR(nd->intent.open.file))
910 goto out;
911 if (IS_ERR(dentry))
912 goto out_err;
913 nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
914 nd->intent.open.flags - 1,
915 nd->intent.open.file,
916 open, cred);
917 out:
918 return nd->intent.open.file;
919 out_err:
920 release_open_intent(nd);
921 nd->intent.open.file = (struct file *)dentry;
922 goto out;
924 EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
927 * nameidata_to_filp - convert a nameidata to an open filp.
928 * @nd: pointer to nameidata
929 * @flags: open flags
931 * Note that this function destroys the original nameidata
933 struct file *nameidata_to_filp(struct nameidata *nd, int flags)
935 const struct cred *cred = current_cred();
936 struct file *filp;
938 /* Pick up the filp from the open intent */
939 filp = nd->intent.open.file;
940 /* Has the filesystem initialised the file for us? */
941 if (filp->f_path.dentry == NULL)
942 filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp,
943 NULL, cred);
944 else
945 path_put(&nd->path);
946 return filp;
950 * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
951 * error.
953 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
954 const struct cred *cred)
956 int error;
957 struct file *f;
960 * We must always pass in a valid mount pointer. Historically
961 * callers got away with not passing it, but we must enforce this at
962 * the earliest possible point now to avoid strange problems deep in the
963 * filesystem stack.
965 if (!mnt) {
966 printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
967 dump_stack();
968 return ERR_PTR(-EINVAL);
971 error = -ENFILE;
972 f = get_empty_filp();
973 if (f == NULL) {
974 dput(dentry);
975 mntput(mnt);
976 return ERR_PTR(error);
979 return __dentry_open(dentry, mnt, flags, f, NULL, cred);
981 EXPORT_SYMBOL(dentry_open);
983 static void __put_unused_fd(struct files_struct *files, unsigned int fd)
985 struct fdtable *fdt = files_fdtable(files);
986 __FD_CLR(fd, fdt->open_fds);
987 if (fd < files->next_fd)
988 files->next_fd = fd;
991 void put_unused_fd(unsigned int fd)
993 struct files_struct *files = current->files;
994 spin_lock(&files->file_lock);
995 __put_unused_fd(files, fd);
996 spin_unlock(&files->file_lock);
999 EXPORT_SYMBOL(put_unused_fd);
1002 * Install a file pointer in the fd array.
1004 * The VFS is full of places where we drop the files lock between
1005 * setting the open_fds bitmap and installing the file in the file
1006 * array. At any such point, we are vulnerable to a dup2() race
1007 * installing a file in the array before us. We need to detect this and
1008 * fput() the struct file we are about to overwrite in this case.
1010 * It should never happen - if we allow dup2() do it, _really_ bad things
1011 * will follow.
1014 void fd_install(unsigned int fd, struct file *file)
1016 struct files_struct *files = current->files;
1017 struct fdtable *fdt;
1018 spin_lock(&files->file_lock);
1019 fdt = files_fdtable(files);
1020 BUG_ON(fdt->fd[fd] != NULL);
1021 rcu_assign_pointer(fdt->fd[fd], file);
1022 spin_unlock(&files->file_lock);
1025 EXPORT_SYMBOL(fd_install);
1027 long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
1029 char *tmp = getname(filename);
1030 int fd = PTR_ERR(tmp);
1032 if (!IS_ERR(tmp)) {
1033 fd = get_unused_fd_flags(flags);
1034 if (fd >= 0) {
1035 struct file *f = do_filp_open(dfd, tmp, flags, mode);
1036 if (IS_ERR(f)) {
1037 put_unused_fd(fd);
1038 fd = PTR_ERR(f);
1039 } else {
1040 fsnotify_open(f->f_path.dentry);
1041 fd_install(fd, f);
1044 putname(tmp);
1046 return fd;
1049 SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, mode)
1051 long ret;
1053 if (force_o_largefile())
1054 flags |= O_LARGEFILE;
1056 ret = do_sys_open(AT_FDCWD, filename, flags, mode);
1057 /* avoid REGPARM breakage on x86: */
1058 asmlinkage_protect(3, ret, filename, flags, mode);
1059 return ret;
1062 SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1063 int, mode)
1065 long ret;
1067 if (force_o_largefile())
1068 flags |= O_LARGEFILE;
1070 ret = do_sys_open(dfd, filename, flags, mode);
1071 /* avoid REGPARM breakage on x86: */
1072 asmlinkage_protect(4, ret, dfd, filename, flags, mode);
1073 return ret;
1076 #ifndef __alpha__
1079 * For backward compatibility? Maybe this should be moved
1080 * into arch/i386 instead?
1082 SYSCALL_DEFINE2(creat, const char __user *, pathname, int, mode)
1084 return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1087 #endif
1090 * "id" is the POSIX thread ID. We use the
1091 * files pointer for this..
1093 int filp_close(struct file *filp, fl_owner_t id)
1095 int retval = 0;
1097 if (!file_count(filp)) {
1098 printk(KERN_ERR "VFS: Close: file count is 0\n");
1099 return 0;
1102 if (filp->f_op && filp->f_op->flush)
1103 retval = filp->f_op->flush(filp, id);
1105 dnotify_flush(filp, id);
1106 locks_remove_posix(filp, id);
1107 fput(filp);
1108 return retval;
1111 EXPORT_SYMBOL(filp_close);
1114 * Careful here! We test whether the file pointer is NULL before
1115 * releasing the fd. This ensures that one clone task can't release
1116 * an fd while another clone is opening it.
1118 SYSCALL_DEFINE1(close, unsigned int, fd)
1120 struct file * filp;
1121 struct files_struct *files = current->files;
1122 struct fdtable *fdt;
1123 int retval;
1125 spin_lock(&files->file_lock);
1126 fdt = files_fdtable(files);
1127 if (fd >= fdt->max_fds)
1128 goto out_unlock;
1129 filp = fdt->fd[fd];
1130 if (!filp)
1131 goto out_unlock;
1132 rcu_assign_pointer(fdt->fd[fd], NULL);
1133 FD_CLR(fd, fdt->close_on_exec);
1134 __put_unused_fd(files, fd);
1135 spin_unlock(&files->file_lock);
1136 retval = filp_close(filp, files);
1138 /* can't restart close syscall because file table entry was cleared */
1139 if (unlikely(retval == -ERESTARTSYS ||
1140 retval == -ERESTARTNOINTR ||
1141 retval == -ERESTARTNOHAND ||
1142 retval == -ERESTART_RESTARTBLOCK))
1143 retval = -EINTR;
1145 return retval;
1147 out_unlock:
1148 spin_unlock(&files->file_lock);
1149 return -EBADF;
1151 EXPORT_SYMBOL(sys_close);
1154 * This routine simulates a hangup on the tty, to arrange that users
1155 * are given clean terminals at login time.
1157 SYSCALL_DEFINE0(vhangup)
1159 if (capable(CAP_SYS_TTY_CONFIG)) {
1160 tty_vhangup_self();
1161 return 0;
1163 return -EPERM;
1167 * Called when an inode is about to be open.
1168 * We use this to disallow opening large files on 32bit systems if
1169 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1170 * on this flag in sys_open.
1172 int generic_file_open(struct inode * inode, struct file * filp)
1174 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1175 return -EOVERFLOW;
1176 return 0;
1179 EXPORT_SYMBOL(generic_file_open);
1182 * This is used by subsystems that don't want seekable
1183 * file descriptors
1185 int nonseekable_open(struct inode *inode, struct file *filp)
1187 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1188 return 0;
1191 EXPORT_SYMBOL(nonseekable_open);