1 /*
2 * linux/fs/open.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7 #include <linux/string.h>
8 #include <linux/mm.h>
9 #include <linux/file.h>
10 #include <linux/quotaops.h>
11 #include <linux/fsnotify.h>
12 #include <linux/module.h>
13 #include <linux/slab.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/security.h>
19 #include <linux/mount.h>
20 #include <linux/vfs.h>
21 #include <linux/fcntl.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
31 int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
32 {
33 int retval = -ENODEV;
34
35 if (dentry) {
36 retval = -ENOSYS;
37 if (dentry->d_sb->s_op->statfs) {
38 memset(buf, 0, sizeof(*buf));
39 retval = security_sb_statfs(dentry);
40 if (retval)
41 return retval;
42 retval = dentry->d_sb->s_op->statfs(dentry, buf);
43 if (retval == 0 && buf->f_frsize == 0)
44 buf->f_frsize = buf->f_bsize;
45 }
46 }
47 return retval;
48 }
49
50 EXPORT_SYMBOL(vfs_statfs);
51
52 static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf)
53 {
54 struct kstatfs st;
55 int retval;
56
57 retval = vfs_statfs(dentry, &st);
58 if (retval)
59 return retval;
60
61 if (sizeof(*buf) == sizeof(st))
62 memcpy(buf, &st, sizeof(st));
63 else {
64 if (sizeof buf->f_blocks == 4) {
65 if ((st.f_blocks | st.f_bfree | st.f_bavail) &
66 0xffffffff00000000ULL)
67 return -EOVERFLOW;
68 /*
69 * f_files and f_ffree may be -1; it's okay to stuff
70 * that into 32 bits
71 */
72 if (st.f_files != -1 &&
73 (st.f_files & 0xffffffff00000000ULL))
74 return -EOVERFLOW;
75 if (st.f_ffree != -1 &&
76 (st.f_ffree & 0xffffffff00000000ULL))
77 return -EOVERFLOW;
78 }
79
80 buf->f_type = st.f_type;
81 buf->f_bsize = st.f_bsize;
82 buf->f_blocks = st.f_blocks;
83 buf->f_bfree = st.f_bfree;
84 buf->f_bavail = st.f_bavail;
85 buf->f_files = st.f_files;
86 buf->f_ffree = st.f_ffree;
87 buf->f_fsid = st.f_fsid;
88 buf->f_namelen = st.f_namelen;
89 buf->f_frsize = st.f_frsize;
90 memset(buf->f_spare, 0, sizeof(buf->f_spare));
91 }
92 return 0;
93 }
94
95 static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf)
96 {
97 struct kstatfs st;
98 int retval;
99
100 retval = vfs_statfs(dentry, &st);
101 if (retval)
102 return retval;
103
104 if (sizeof(*buf) == sizeof(st))
105 memcpy(buf, &st, sizeof(st));
106 else {
107 buf->f_type = st.f_type;
108 buf->f_bsize = st.f_bsize;
109 buf->f_blocks = st.f_blocks;
110 buf->f_bfree = st.f_bfree;
111 buf->f_bavail = st.f_bavail;
112 buf->f_files = st.f_files;
113 buf->f_ffree = st.f_ffree;
114 buf->f_fsid = st.f_fsid;
115 buf->f_namelen = st.f_namelen;
116 buf->f_frsize = st.f_frsize;
117 memset(buf->f_spare, 0, sizeof(buf->f_spare));
118 }
119 return 0;
120 }
121
122 asmlinkage long sys_statfs(const char __user * path, struct statfs __user * buf)
123 {
124 struct nameidata nd;
125 int error;
126
127 error = user_path_walk(path, &nd);
128 if (!error) {
129 struct statfs tmp;
130 error = vfs_statfs_native(nd.path.dentry, &tmp);
131 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
132 error = -EFAULT;
133 path_put(&nd.path);
134 }
135 return error;
136 }
137
138
139 asmlinkage long sys_statfs64(const char __user *path, size_t sz, struct statfs64 __user *buf)
140 {
141 struct nameidata nd;
142 long error;
143
144 if (sz != sizeof(*buf))
145 return -EINVAL;
146 error = user_path_walk(path, &nd);
147 if (!error) {
148 struct statfs64 tmp;
149 error = vfs_statfs64(nd.path.dentry, &tmp);
150 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
151 error = -EFAULT;
152 path_put(&nd.path);
153 }
154 return error;
155 }
156
157
158 asmlinkage long sys_fstatfs(unsigned int fd, struct statfs __user * buf)
159 {
160 struct file * file;
161 struct statfs tmp;
162 int error;
163
164 error = -EBADF;
165 file = fget(fd);
166 if (!file)
167 goto out;
168 error = vfs_statfs_native(file->f_path.dentry, &tmp);
169 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
170 error = -EFAULT;
171 fput(file);
172 out:
173 return error;
174 }
175
176 asmlinkage long sys_fstatfs64(unsigned int fd, size_t sz, struct statfs64 __user *buf)
177 {
178 struct file * file;
179 struct statfs64 tmp;
180 int error;
181
182 if (sz != sizeof(*buf))
183 return -EINVAL;
184
185 error = -EBADF;
186 file = fget(fd);
187 if (!file)
188 goto out;
189 error = vfs_statfs64(file->f_path.dentry, &tmp);
190 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
191 error = -EFAULT;
192 fput(file);
193 out:
194 return error;
195 }
196
197 int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
198 struct file *filp)
199 {
200 int err;
201 struct iattr newattrs;
202
203 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
204 if (length < 0)
205 return -EINVAL;
206
207 newattrs.ia_size = length;
208 newattrs.ia_valid = ATTR_SIZE | time_attrs;
209 if (filp) {
210 newattrs.ia_file = filp;
211 newattrs.ia_valid |= ATTR_FILE;
212 }
213
214 /* Remove suid/sgid on truncate too */
215 newattrs.ia_valid |= should_remove_suid(dentry);
216
217 mutex_lock(&dentry->d_inode->i_mutex);
218 err = notify_change(dentry, &newattrs);
219 mutex_unlock(&dentry->d_inode->i_mutex);
220 return err;
221 }
222
223 static long do_sys_truncate(const char __user * path, loff_t length)
224 {
225 struct nameidata nd;
226 struct inode * inode;
227 int error;
228
229 error = -EINVAL;
230 if (length < 0) /* sorry, but loff_t says... */
231 goto out;
232
233 error = user_path_walk(path, &nd);
234 if (error)
235 goto out;
236 inode = nd.path.dentry->d_inode;
237
238 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
239 error = -EISDIR;
240 if (S_ISDIR(inode->i_mode))
241 goto dput_and_out;
242
243 error = -EINVAL;
244 if (!S_ISREG(inode->i_mode))
245 goto dput_and_out;
246
247 error = vfs_permission(&nd, MAY_WRITE);
248 if (error)
249 goto dput_and_out;
250
251 error = -EROFS;
252 if (IS_RDONLY(inode))
253 goto dput_and_out;
254
255 error = -EPERM;
256 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
257 goto dput_and_out;
258
259 error = get_write_access(inode);
260 if (error)
261 goto dput_and_out;
262
263 /*
264 * Make sure that there are no leases. get_write_access() protects
265 * against the truncate racing with a lease-granting setlease().
266 */
267 error = break_lease(inode, FMODE_WRITE);
268 if (error)
269 goto put_write_and_out;
270
271 error = locks_verify_truncate(inode, NULL, length);
272 if (!error) {
273 DQUOT_INIT(inode);
274 error = do_truncate(nd.path.dentry, length, 0, NULL);
275 }
276
277 put_write_and_out:
278 put_write_access(inode);
279 dput_and_out:
280 path_put(&nd.path);
281 out:
282 return error;
283 }
284
285 asmlinkage long sys_truncate(const char __user * path, unsigned long length)
286 {
287 /* on 32-bit boxen it will cut the range 2^31--2^32-1 off */
288 return do_sys_truncate(path, (long)length);
289 }
290
291 static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
292 {
293 struct inode * inode;
294 struct dentry *dentry;
295 struct file * file;
296 int error;
297
298 error = -EINVAL;
299 if (length < 0)
300 goto out;
301 error = -EBADF;
302 file = fget(fd);
303 if (!file)
304 goto out;
305
306 /* explicitly opened as large or we are on 64-bit box */
307 if (file->f_flags & O_LARGEFILE)
308 small = 0;
309
310 dentry = file->f_path.dentry;
311 inode = dentry->d_inode;
312 error = -EINVAL;
313 if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
314 goto out_putf;
315
316 error = -EINVAL;
317 /* Cannot ftruncate over 2^31 bytes without large file support */
318 if (small && length > MAX_NON_LFS)
319 goto out_putf;
320
321 error = -EPERM;
322 if (IS_APPEND(inode))
323 goto out_putf;
324
325 error = locks_verify_truncate(inode, file, length);
326 if (!error)
327 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
328 out_putf:
329 fput(file);
330 out:
331 return error;
332 }
333
334 asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length)
335 {
336 long ret = do_sys_ftruncate(fd, length, 1);
337 /* avoid REGPARM breakage on x86: */
338 asmlinkage_protect(2, ret, fd, length);
339 return ret;
340 }
341
342 /* LFS versions of truncate are only needed on 32 bit machines */
343 #if BITS_PER_LONG == 32
344 asmlinkage long sys_truncate64(const char __user * path, loff_t length)
345 {
346 return do_sys_truncate(path, length);
347 }
348
349 asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
350 {
351 long ret = do_sys_ftruncate(fd, length, 0);
352 /* avoid REGPARM breakage on x86: */
353 asmlinkage_protect(2, ret, fd, length);
354 return ret;
355 }
356 #endif
357
358 asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len)
359 {
360 struct file *file;
361 struct inode *inode;
362 long ret = -EINVAL;
363
364 if (offset < 0 || len <= 0)
365 goto out;
366
367 /* Return error if mode is not supported */
368 ret = -EOPNOTSUPP;
369 if (mode && !(mode & FALLOC_FL_KEEP_SIZE))
370 goto out;
371
372 ret = -EBADF;
373 file = fget(fd);
374 if (!file)
375 goto out;
376 if (!(file->f_mode & FMODE_WRITE))
377 goto out_fput;
378 /*
379 * Revalidate the write permissions, in case security policy has
380 * changed since the files were opened.
381 */
382 ret = security_file_permission(file, MAY_WRITE);
383 if (ret)
384 goto out_fput;
385
386 inode = file->f_path.dentry->d_inode;
387
388 ret = -ESPIPE;
389 if (S_ISFIFO(inode->i_mode))
390 goto out_fput;
391
392 ret = -ENODEV;
393 /*
394 * Let individual file system decide if it supports preallocation
395 * for directories or not.
396 */
397 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
398 goto out_fput;
399
400 ret = -EFBIG;
401 /* Check for wrap through zero too */
402 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
403 goto out_fput;
404
405 if (inode->i_op && inode->i_op->fallocate)
406 ret = inode->i_op->fallocate(inode, mode, offset, len);
407 else
408 ret = -EOPNOTSUPP;
409
410 out_fput:
411 fput(file);
412 out:
413 return ret;
414 }
415
416 /*
417 * access() needs to use the real uid/gid, not the effective uid/gid.
418 * We do this by temporarily clearing all FS-related capabilities and
419 * switching the fsuid/fsgid around to the real ones.
420 */
421 asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
422 {
423 struct nameidata nd;
424 int old_fsuid, old_fsgid;
425 kernel_cap_t old_cap;
426 int res;
427
428 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
429 return -EINVAL;
430
431 old_fsuid = current->fsuid;
432 old_fsgid = current->fsgid;
433 old_cap = current->cap_effective;
434
435 current->fsuid = current->uid;
436 current->fsgid = current->gid;
437
438 /*
439 * Clear the capabilities if we switch to a non-root user
440 *
441 * FIXME: There is a race here against sys_capset. The
442 * capabilities can change yet we will restore the old
443 * value below. We should hold task_capabilities_lock,
444 * but we cannot because user_path_walk can sleep.
445 */
446 if (current->uid)
447 cap_clear(current->cap_effective);
448 else
449 current->cap_effective = current->cap_permitted;
450
451 res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd);
452 if (res)
453 goto out;
454
455 res = vfs_permission(&nd, mode);
456 /* SuS v2 requires we report a read only fs too */
457 if(res || !(mode & S_IWOTH) ||
458 special_file(nd.path.dentry->d_inode->i_mode))
459 goto out_path_release;
460
461 if(IS_RDONLY(nd.path.dentry->d_inode))
462 res = -EROFS;
463
464 out_path_release:
465 path_put(&nd.path);
466 out:
467 current->fsuid = old_fsuid;
468 current->fsgid = old_fsgid;
469 current->cap_effective = old_cap;
470
471 return res;
472 }
473
474 asmlinkage long sys_access(const char __user *filename, int mode)
475 {
476 return sys_faccessat(AT_FDCWD, filename, mode);
477 }
478
479 asmlinkage long sys_chdir(const char __user * filename)
480 {
481 struct nameidata nd;
482 int error;
483
484 error = __user_walk(filename,
485 LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd);
486 if (error)
487 goto out;
488
489 error = vfs_permission(&nd, MAY_EXEC);
490 if (error)
491 goto dput_and_out;
492
493 set_fs_pwd(current->fs, &nd.path);
494
495 dput_and_out:
496 path_put(&nd.path);
497 out:
498 return error;
499 }
500
501 asmlinkage long sys_fchdir(unsigned int fd)
502 {
503 struct file *file;
504 struct inode *inode;
505 int error;
506
507 error = -EBADF;
508 file = fget(fd);
509 if (!file)
510 goto out;
511
512 inode = file->f_path.dentry->d_inode;
513
514 error = -ENOTDIR;
515 if (!S_ISDIR(inode->i_mode))
516 goto out_putf;
517
518 error = file_permission(file, MAY_EXEC);
519 if (!error)
520 set_fs_pwd(current->fs, &file->f_path);
521 out_putf:
522 fput(file);
523 out:
524 return error;
525 }
526
527 asmlinkage long sys_chroot(const char __user * filename)
528 {
529 struct nameidata nd;
530 int error;
531
532 error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd);
533 if (error)
534 goto out;
535
536 error = vfs_permission(&nd, MAY_EXEC);
537 if (error)
538 goto dput_and_out;
539
540 error = -EPERM;
541 if (!capable(CAP_SYS_CHROOT))
542 goto dput_and_out;
543
544 set_fs_root(current->fs, &nd.path);
545 set_fs_altroot();
546 error = 0;
547 dput_and_out:
548 path_put(&nd.path);
549 out:
550 return error;
551 }
552
553 asmlinkage long sys_fchmod(unsigned int fd, mode_t mode)
554 {
555 struct inode * inode;
556 struct dentry * dentry;
557 struct file * file;
558 int err = -EBADF;
559 struct iattr newattrs;
560
561 file = fget(fd);
562 if (!file)
563 goto out;
564
565 dentry = file->f_path.dentry;
566 inode = dentry->d_inode;
567
568 audit_inode(NULL, dentry);
569
570 err = -EROFS;
571 if (IS_RDONLY(inode))
572 goto out_putf;
573 err = -EPERM;
574 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
575 goto out_putf;
576 mutex_lock(&inode->i_mutex);
577 if (mode == (mode_t) -1)
578 mode = inode->i_mode;
579 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
580 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
581 err = notify_change(dentry, &newattrs);
582 mutex_unlock(&inode->i_mutex);
583
584 out_putf:
585 fput(file);
586 out:
587 return err;
588 }
589
590 asmlinkage long sys_fchmodat(int dfd, const char __user *filename,
591 mode_t mode)
592 {
593 struct nameidata nd;
594 struct inode * inode;
595 int error;
596 struct iattr newattrs;
597
598 error = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd);
599 if (error)
600 goto out;
601 inode = nd.path.dentry->d_inode;
602
603 error = -EROFS;
604 if (IS_RDONLY(inode))
605 goto dput_and_out;
606
607 error = -EPERM;
608 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
609 goto dput_and_out;
610
611 mutex_lock(&inode->i_mutex);
612 if (mode == (mode_t) -1)
613 mode = inode->i_mode;
614 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
615 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
616 error = notify_change(nd.path.dentry, &newattrs);
617 mutex_unlock(&inode->i_mutex);
618
619 dput_and_out:
620 path_put(&nd.path);
621 out:
622 return error;
623 }
624
625 asmlinkage long sys_chmod(const char __user *filename, mode_t mode)
626 {
627 return sys_fchmodat(AT_FDCWD, filename, mode);
628 }
629
630 static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
631 {
632 struct inode * inode;
633 int error;
634 struct iattr newattrs;
635
636 error = -ENOENT;
637 if (!(inode = dentry->d_inode)) {
638 printk(KERN_ERR "chown_common: NULL inode\n");
639 goto out;
640 }
641 error = -EROFS;
642 if (IS_RDONLY(inode))
643 goto out;
644 error = -EPERM;
645 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
646 goto out;
647 newattrs.ia_valid = ATTR_CTIME;
648 if (user != (uid_t) -1) {
649 newattrs.ia_valid |= ATTR_UID;
650 newattrs.ia_uid = user;
651 }
652 if (group != (gid_t) -1) {
653 newattrs.ia_valid |= ATTR_GID;
654 newattrs.ia_gid = group;
655 }
656 if (!S_ISDIR(inode->i_mode))
657 newattrs.ia_valid |=
658 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
659 mutex_lock(&inode->i_mutex);
660 error = notify_change(dentry, &newattrs);
661 mutex_unlock(&inode->i_mutex);
662 out:
663 return error;
664 }
665
666 asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group)
667 {
668 struct nameidata nd;
669 int error;
670
671 error = user_path_walk(filename, &nd);
672 if (error)
673 goto out;
674 error = chown_common(nd.path.dentry, user, group);
675 path_put(&nd.path);
676 out:
677 return error;
678 }
679
680 asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user,
681 gid_t group, int flag)
682 {
683 struct nameidata nd;
684 int error = -EINVAL;
685 int follow;
686
687 if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
688 goto out;
689
690 follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
691 error = __user_walk_fd(dfd, filename, follow, &nd);
692 if (error)
693 goto out;
694 error = chown_common(nd.path.dentry, user, group);
695 path_put(&nd.path);
696 out:
697 return error;
698 }
699
700 asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group)
701 {
702 struct nameidata nd;
703 int error;
704
705 error = user_path_walk_link(filename, &nd);
706 if (error)
707 goto out;
708 error = chown_common(nd.path.dentry, user, group);
709 path_put(&nd.path);
710 out:
711 return error;
712 }
713
714
715 asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
716 {
717 struct file * file;
718 int error = -EBADF;
719 struct dentry * dentry;
720
721 file = fget(fd);
722 if (!file)
723 goto out;
724
725 dentry = file->f_path.dentry;
726 audit_inode(NULL, dentry);
727 error = chown_common(dentry, user, group);
728 fput(file);
729 out:
730 return error;
731 }
732
733 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
734 int flags, struct file *f,
735 int (*open)(struct inode *, struct file *))
736 {
737 struct inode *inode;
738 int error;
739
740 f->f_flags = flags;
741 f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK |
742 FMODE_PREAD | FMODE_PWRITE;
743 inode = dentry->d_inode;
744 if (f->f_mode & FMODE_WRITE) {
745 error = get_write_access(inode);
746 if (error)
747 goto cleanup_file;
748 }
749
750 f->f_mapping = inode->i_mapping;
751 f->f_path.dentry = dentry;
752 f->f_path.mnt = mnt;
753 f->f_pos = 0;
754 f->f_op = fops_get(inode->i_fop);
755 file_move(f, &inode->i_sb->s_files);
756
757 error = security_dentry_open(f);
758 if (error)
759 goto cleanup_all;
760
761 if (!open && f->f_op)
762 open = f->f_op->open;
763 if (open) {
764 error = open(inode, f);
765 if (error)
766 goto cleanup_all;
767 }
768
769 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
770
771 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
772
773 /* NB: we're sure to have correct a_ops only after f_op->open */
774 if (f->f_flags & O_DIRECT) {
775 if (!f->f_mapping->a_ops ||
776 ((!f->f_mapping->a_ops->direct_IO) &&
777 (!f->f_mapping->a_ops->get_xip_page))) {
778 fput(f);
779 f = ERR_PTR(-EINVAL);
780 }
781 }
782
783 return f;
784
785 cleanup_all:
786 fops_put(f->f_op);
787 if (f->f_mode & FMODE_WRITE)
788 put_write_access(inode);
789 file_kill(f);
790 f->f_path.dentry = NULL;
791 f->f_path.mnt = NULL;
792 cleanup_file:
793 put_filp(f);
794 dput(dentry);
795 mntput(mnt);
796 return ERR_PTR(error);
797 }
798
799 /*
800 * Note that while the flag value (low two bits) for sys_open means:
801 * 00 - read-only
802 * 01 - write-only
803 * 10 - read-write
804 * 11 - special
805 * it is changed into
806 * 00 - no permissions needed
807 * 01 - read-permission
808 * 10 - write-permission
809 * 11 - read-write
810 * for the internal routines (ie open_namei()/follow_link() etc). 00 is
811 * used by symlinks.
812 */
813 static struct file *do_filp_open(int dfd, const char *filename, int flags,
814 int mode)
815 {
816 int namei_flags, error;
817 struct nameidata nd;
818
819 namei_flags = flags;
820 if ((namei_flags+1) & O_ACCMODE)
821 namei_flags++;
822
823 error = open_namei(dfd, filename, namei_flags, mode, &nd);
824 if (!error)
825 return nameidata_to_filp(&nd, flags);
826
827 return ERR_PTR(error);
828 }
829
830 struct file *filp_open(const char *filename, int flags, int mode)
831 {
832 return do_filp_open(AT_FDCWD, filename, flags, mode);
833 }
834 EXPORT_SYMBOL(filp_open);
835
836 /**
837 * lookup_instantiate_filp - instantiates the open intent filp
838 * @nd: pointer to nameidata
839 * @dentry: pointer to dentry
840 * @open: open callback
841 *
842 * Helper for filesystems that want to use lookup open intents and pass back
843 * a fully instantiated struct file to the caller.
844 * This function is meant to be called from within a filesystem's
845 * lookup method.
846 * Beware of calling it for non-regular files! Those ->open methods might block
847 * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
848 * leading to a deadlock, as nobody can open that fifo anymore, because
849 * another process to open fifo will block on locked parent when doing lookup).
850 * Note that in case of error, nd->intent.open.file is destroyed, but the
851 * path information remains valid.
852 * If the open callback is set to NULL, then the standard f_op->open()
853 * filesystem callback is substituted.
854 */
855 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
856 int (*open)(struct inode *, struct file *))
857 {
858 if (IS_ERR(nd->intent.open.file))
859 goto out;
860 if (IS_ERR(dentry))
861 goto out_err;
862 nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt),
863 nd->intent.open.flags - 1,
864 nd->intent.open.file,
865 open);
866 out:
867 return nd->intent.open.file;
868 out_err:
869 release_open_intent(nd);
870 nd->intent.open.file = (struct file *)dentry;
871 goto out;
872 }
873 EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
874
875 /**
876 * nameidata_to_filp - convert a nameidata to an open filp.
877 * @nd: pointer to nameidata
878 * @flags: open flags
879 *
880 * Note that this function destroys the original nameidata
881 */
882 struct file *nameidata_to_filp(struct nameidata *nd, int flags)
883 {
884 struct file *filp;
885
886 /* Pick up the filp from the open intent */
887 filp = nd->intent.open.file;
888 /* Has the filesystem initialised the file for us? */
889 if (filp->f_path.dentry == NULL)
890 filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp,
891 NULL);
892 else
893 path_put(&nd->path);
894 return filp;
895 }
896
897 /*
898 * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
899 * error.
900 */
901 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
902 {
903 int error;
904 struct file *f;
905
906 /*
907 * We must always pass in a valid mount pointer. Historically
908 * callers got away with not passing it, but we must enforce this at
909 * the earliest possible point now to avoid strange problems deep in the
910 * filesystem stack.
911 */
912 if (!mnt) {
913 printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
914 dump_stack();
915 return ERR_PTR(-EINVAL);
916 }
917
918 error = -ENFILE;
919 f = get_empty_filp();
920 if (f == NULL) {
921 dput(dentry);
922 mntput(mnt);
923 return ERR_PTR(error);
924 }
925
926 return __dentry_open(dentry, mnt, flags, f, NULL);
927 }
928 EXPORT_SYMBOL(dentry_open);
929
930 /*
931 * Find an empty file descriptor entry, and mark it busy.
932 */
933 int get_unused_fd_flags(int flags)
934 {
935 struct files_struct * files = current->files;
936 int fd, error;
937 struct fdtable *fdt;
938
939 error = -EMFILE;
940 spin_lock(&files->file_lock);
941
942 repeat:
943 fdt = files_fdtable(files);
944 fd = find_next_zero_bit(fdt->open_fds->fds_bits, fdt->max_fds,
945 files->next_fd);
946
947 /*
948 * N.B. For clone tasks sharing a files structure, this test
949 * will limit the total number of files that can be opened.
950 */
951 if (fd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
952 goto out;
953
954 /* Do we need to expand the fd array or fd set? */
955 error = expand_files(files, fd);
956 if (error < 0)
957 goto out;
958
959 if (error) {
960 /*
961 * If we needed to expand the fs array we
962 * might have blocked - try again.
963 */
964 error = -EMFILE;
965 goto repeat;
966 }
967
968 FD_SET(fd, fdt->open_fds);
969 if (flags & O_CLOEXEC)
970 FD_SET(fd, fdt->close_on_exec);
971 else
972 FD_CLR(fd, fdt->close_on_exec);
973 files->next_fd = fd + 1;
974 #if 1
975 /* Sanity check */
976 if (fdt->fd[fd] != NULL) {
977 printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd);
978 fdt->fd[fd] = NULL;
979 }
980 #endif
981 error = fd;
982
983 out:
984 spin_unlock(&files->file_lock);
985 return error;
986 }
987
988 int get_unused_fd(void)
989 {
990 return get_unused_fd_flags(0);
991 }
992
993 EXPORT_SYMBOL(get_unused_fd);
994
995 static void __put_unused_fd(struct files_struct *files, unsigned int fd)
996 {
997 struct fdtable *fdt = files_fdtable(files);
998 __FD_CLR(fd, fdt->open_fds);
999 if (fd < files->next_fd)
1000 files->next_fd = fd;
1001 }
1002
1003 void put_unused_fd(unsigned int fd)
1004 {
1005 struct files_struct *files = current->files;
1006 spin_lock(&files->file_lock);
1007 __put_unused_fd(files, fd);
1008 spin_unlock(&files->file_lock);
1009 }
1010
1011 EXPORT_SYMBOL(put_unused_fd);
1012
1013 /*
1014 * Install a file pointer in the fd array.
1015 *
1016 * The VFS is full of places where we drop the files lock between
1017 * setting the open_fds bitmap and installing the file in the file
1018 * array. At any such point, we are vulnerable to a dup2() race
1019 * installing a file in the array before us. We need to detect this and
1020 * fput() the struct file we are about to overwrite in this case.
1021 *
1022 * It should never happen - if we allow dup2() do it, _really_ bad things
1023 * will follow.
1024 */
1025
1026 void fd_install(unsigned int fd, struct file *file)
1027 {
1028 struct files_struct *files = current->files;
1029 struct fdtable *fdt;
1030 spin_lock(&files->file_lock);
1031 fdt = files_fdtable(files);
1032 BUG_ON(fdt->fd[fd] != NULL);
1033 rcu_assign_pointer(fdt->fd[fd], file);
1034 spin_unlock(&files->file_lock);
1035 }
1036
1037 EXPORT_SYMBOL(fd_install);
1038
1039 long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
1040 {
1041 char *tmp = getname(filename);
1042 int fd = PTR_ERR(tmp);
1043
1044 if (!IS_ERR(tmp)) {
1045 fd = get_unused_fd_flags(flags);
1046 if (fd >= 0) {
1047 struct file *f = do_filp_open(dfd, tmp, flags, mode);
1048 if (IS_ERR(f)) {
1049 put_unused_fd(fd);
1050 fd = PTR_ERR(f);
1051 } else {
1052 fsnotify_open(f->f_path.dentry);
1053 fd_install(fd, f);
1054 }
1055 }
1056 putname(tmp);
1057 }
1058 return fd;
1059 }
1060
1061 asmlinkage long sys_open(const char __user *filename, int flags, int mode)
1062 {
1063 long ret;
1064
1065 if (force_o_largefile())
1066 flags |= O_LARGEFILE;
1067
1068 ret = do_sys_open(AT_FDCWD, filename, flags, mode);
1069 /* avoid REGPARM breakage on x86: */
1070 asmlinkage_protect(3, ret, filename, flags, mode);
1071 return ret;
1072 }
1073
1074 asmlinkage long sys_openat(int dfd, const char __user *filename, int flags,
1075 int mode)
1076 {
1077 long ret;
1078
1079 if (force_o_largefile())
1080 flags |= O_LARGEFILE;
1081
1082 ret = do_sys_open(dfd, filename, flags, mode);
1083 /* avoid REGPARM breakage on x86: */
1084 asmlinkage_protect(4, ret, dfd, filename, flags, mode);
1085 return ret;
1086 }
1087
1088 #ifndef __alpha__
1089
1090 /*
1091 * For backward compatibility? Maybe this should be moved
1092 * into arch/i386 instead?
1093 */
1094 asmlinkage long sys_creat(const char __user * pathname, int mode)
1095 {
1096 return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1097 }
1098
1099 #endif
1100
1101 /*
1102 * "id" is the POSIX thread ID. We use the
1103 * files pointer for this..
1104 */
1105 int filp_close(struct file *filp, fl_owner_t id)
1106 {
1107 int retval = 0;
1108
1109 if (!file_count(filp)) {
1110 printk(KERN_ERR "VFS: Close: file count is 0\n");
1111 return 0;
1112 }
1113
1114 if (filp->f_op && filp->f_op->flush)
1115 retval = filp->f_op->flush(filp, id);
1116
1117 dnotify_flush(filp, id);
1118 locks_remove_posix(filp, id);
1119 fput(filp);
1120 return retval;
1121 }
1122
1123 EXPORT_SYMBOL(filp_close);
1124
1125 /*
1126 * Careful here! We test whether the file pointer is NULL before
1127 * releasing the fd. This ensures that one clone task can't release
1128 * an fd while another clone is opening it.
1129 */
1130 asmlinkage long sys_close(unsigned int fd)
1131 {
1132 struct file * filp;
1133 struct files_struct *files = current->files;
1134 struct fdtable *fdt;
1135 int retval;
1136
1137 spin_lock(&files->file_lock);
1138 fdt = files_fdtable(files);
1139 if (fd >= fdt->max_fds)
1140 goto out_unlock;
1141 filp = fdt->fd[fd];
1142 if (!filp)
1143 goto out_unlock;
1144 rcu_assign_pointer(fdt->fd[fd], NULL);
1145 FD_CLR(fd, fdt->close_on_exec);
1146 __put_unused_fd(files, fd);
1147 spin_unlock(&files->file_lock);
1148 retval = filp_close(filp, files);
1149
1150 /* can't restart close syscall because file table entry was cleared */
1151 if (unlikely(retval == -ERESTARTSYS ||
1152 retval == -ERESTARTNOINTR ||
1153 retval == -ERESTARTNOHAND ||
1154 retval == -ERESTART_RESTARTBLOCK))
1155 retval = -EINTR;
1156
1157 return retval;
1158
1159 out_unlock:
1160 spin_unlock(&files->file_lock);
1161 return -EBADF;
1162 }
1163
1164 EXPORT_SYMBOL(sys_close);
1165
1166 /*
1167 * This routine simulates a hangup on the tty, to arrange that users
1168 * are given clean terminals at login time.
1169 */
1170 asmlinkage long sys_vhangup(void)
1171 {
1172 if (capable(CAP_SYS_TTY_CONFIG)) {
1173 /* XXX: this needs locking */
1174 tty_vhangup(current->signal->tty);
1175 return 0;
1176 }
1177 return -EPERM;
1178 }
1179
1180 /*
1181 * Called when an inode is about to be open.
1182 * We use this to disallow opening large files on 32bit systems if
1183 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1184 * on this flag in sys_open.
1185 */
1186 int generic_file_open(struct inode * inode, struct file * filp)
1187 {
1188 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1189 return -EOVERFLOW;
1190 return 0;
1191 }
1192
1193 EXPORT_SYMBOL(generic_file_open);
1194
1195 /*
1196 * This is used by subsystems that don't want seekable
1197 * file descriptors
1198 */
1199 int nonseekable_open(struct inode *inode, struct file *filp)
1200 {
1201 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1202 return 0;
1203 }
1204
1205 EXPORT_SYMBOL(nonseekable_open);
1206
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