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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/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>
33#include <linux/compat.h>
34
35#include "internal.h"
36
37int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
38 struct file *filp)
39{
40 int ret;
41 struct iattr newattrs;
42
43 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
44 if (length < 0)
45 return -EINVAL;
46
47 newattrs.ia_size = length;
48 newattrs.ia_valid = ATTR_SIZE | time_attrs;
49 if (filp) {
50 newattrs.ia_file = filp;
51 newattrs.ia_valid |= ATTR_FILE;
52 }
53
54 /* Remove suid/sgid on truncate too */
55 ret = should_remove_suid(dentry);
56 if (ret)
57 newattrs.ia_valid |= ret | ATTR_FORCE;
58
59 mutex_lock(&dentry->d_inode->i_mutex);
60 /* Note any delegations or leases have already been broken: */
61 ret = notify_change(dentry, &newattrs, NULL);
62 mutex_unlock(&dentry->d_inode->i_mutex);
63 return ret;
64}
65
66long vfs_truncate(struct path *path, loff_t length)
67{
68 struct inode *inode;
69 long error;
70
71 inode = path->dentry->d_inode;
72
73 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
74 if (S_ISDIR(inode->i_mode))
75 return -EISDIR;
76 if (!S_ISREG(inode->i_mode))
77 return -EINVAL;
78
79 error = mnt_want_write(path->mnt);
80 if (error)
81 goto out;
82
83 error = inode_permission(inode, MAY_WRITE);
84 if (error)
85 goto mnt_drop_write_and_out;
86
87 error = -EPERM;
88 if (IS_APPEND(inode))
89 goto mnt_drop_write_and_out;
90
91 error = get_write_access(inode);
92 if (error)
93 goto mnt_drop_write_and_out;
94
95 /*
96 * Make sure that there are no leases. get_write_access() protects
97 * against the truncate racing with a lease-granting setlease().
98 */
99 error = break_lease(inode, O_WRONLY);
100 if (error)
101 goto put_write_and_out;
102
103 error = locks_verify_truncate(inode, NULL, length);
104 if (!error)
105 error = security_path_truncate(path);
106 if (!error)
107 error = do_truncate(path->dentry, length, 0, NULL);
108
109put_write_and_out:
110 put_write_access(inode);
111mnt_drop_write_and_out:
112 mnt_drop_write(path->mnt);
113out:
114 return error;
115}
116EXPORT_SYMBOL_GPL(vfs_truncate);
117
118static long do_sys_truncate(const char __user *pathname, loff_t length)
119{
120 unsigned int lookup_flags = LOOKUP_FOLLOW;
121 struct path path;
122 int error;
123
124 if (length < 0) /* sorry, but loff_t says... */
125 return -EINVAL;
126
127retry:
128 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
129 if (!error) {
130 error = vfs_truncate(&path, length);
131 path_put(&path);
132 }
133 if (retry_estale(error, lookup_flags)) {
134 lookup_flags |= LOOKUP_REVAL;
135 goto retry;
136 }
137 return error;
138}
139
140SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
141{
142 return do_sys_truncate(path, length);
143}
144
145#ifdef CONFIG_COMPAT
146COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
147{
148 return do_sys_truncate(path, length);
149}
150#endif
151
152static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
153{
154 struct inode *inode;
155 struct dentry *dentry;
156 struct fd f;
157 int error;
158
159 error = -EINVAL;
160 if (length < 0)
161 goto out;
162 error = -EBADF;
163 f = fdget(fd);
164 if (!f.file)
165 goto out;
166
167 /* explicitly opened as large or we are on 64-bit box */
168 if (f.file->f_flags & O_LARGEFILE)
169 small = 0;
170
171 dentry = f.file->f_path.dentry;
172 inode = dentry->d_inode;
173 error = -EINVAL;
174 if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
175 goto out_putf;
176
177 error = -EINVAL;
178 /* Cannot ftruncate over 2^31 bytes without large file support */
179 if (small && length > MAX_NON_LFS)
180 goto out_putf;
181
182 error = -EPERM;
183 if (IS_APPEND(inode))
184 goto out_putf;
185
186 sb_start_write(inode->i_sb);
187 error = locks_verify_truncate(inode, f.file, length);
188 if (!error)
189 error = security_path_truncate(&f.file->f_path);
190 if (!error)
191 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
192 sb_end_write(inode->i_sb);
193out_putf:
194 fdput(f);
195out:
196 return error;
197}
198
199SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
200{
201 return do_sys_ftruncate(fd, length, 1);
202}
203
204#ifdef CONFIG_COMPAT
205COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
206{
207 return do_sys_ftruncate(fd, length, 1);
208}
209#endif
210
211/* LFS versions of truncate are only needed on 32 bit machines */
212#if BITS_PER_LONG == 32
213SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
214{
215 return do_sys_truncate(path, length);
216}
217
218SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
219{
220 return do_sys_ftruncate(fd, length, 0);
221}
222#endif /* BITS_PER_LONG == 32 */
223
224
225int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
226{
227 struct inode *inode = file_inode(file);
228 long ret;
229
230 if (offset < 0 || len <= 0)
231 return -EINVAL;
232
233 /* Return error if mode is not supported */
234 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
235 FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE))
236 return -EOPNOTSUPP;
237
238 /* Punch hole and zero range are mutually exclusive */
239 if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
240 (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
241 return -EOPNOTSUPP;
242
243 /* Punch hole must have keep size set */
244 if ((mode & FALLOC_FL_PUNCH_HOLE) &&
245 !(mode & FALLOC_FL_KEEP_SIZE))
246 return -EOPNOTSUPP;
247
248 /* Collapse range should only be used exclusively. */
249 if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
250 (mode & ~FALLOC_FL_COLLAPSE_RANGE))
251 return -EINVAL;
252
253 if (!(file->f_mode & FMODE_WRITE))
254 return -EBADF;
255
256 /*
257 * We can only allow pure fallocate on append only files
258 */
259 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
260 return -EPERM;
261
262 if (IS_IMMUTABLE(inode))
263 return -EPERM;
264
265 /*
266 * We can not allow to do any fallocate operation on an active
267 * swapfile
268 */
269 if (IS_SWAPFILE(inode))
270 ret = -ETXTBSY;
271
272 /*
273 * Revalidate the write permissions, in case security policy has
274 * changed since the files were opened.
275 */
276 ret = security_file_permission(file, MAY_WRITE);
277 if (ret)
278 return ret;
279
280 if (S_ISFIFO(inode->i_mode))
281 return -ESPIPE;
282
283 /*
284 * Let individual file system decide if it supports preallocation
285 * for directories or not.
286 */
287 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
288 return -ENODEV;
289
290 /* Check for wrap through zero too */
291 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
292 return -EFBIG;
293
294 if (!file->f_op->fallocate)
295 return -EOPNOTSUPP;
296
297 sb_start_write(inode->i_sb);
298 ret = file->f_op->fallocate(file, mode, offset, len);
299 sb_end_write(inode->i_sb);
300 return ret;
301}
302
303SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
304{
305 struct fd f = fdget(fd);
306 int error = -EBADF;
307
308 if (f.file) {
309 error = do_fallocate(f.file, mode, offset, len);
310 fdput(f);
311 }
312 return error;
313}
314
315/*
316 * access() needs to use the real uid/gid, not the effective uid/gid.
317 * We do this by temporarily clearing all FS-related capabilities and
318 * switching the fsuid/fsgid around to the real ones.
319 */
320SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
321{
322 const struct cred *old_cred;
323 struct cred *override_cred;
324 struct path path;
325 struct inode *inode;
326 int res;
327 unsigned int lookup_flags = LOOKUP_FOLLOW;
328
329 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
330 return -EINVAL;
331
332 override_cred = prepare_creds();
333 if (!override_cred)
334 return -ENOMEM;
335
336 override_cred->fsuid = override_cred->uid;
337 override_cred->fsgid = override_cred->gid;
338
339 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
340 /* Clear the capabilities if we switch to a non-root user */
341 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
342 if (!uid_eq(override_cred->uid, root_uid))
343 cap_clear(override_cred->cap_effective);
344 else
345 override_cred->cap_effective =
346 override_cred->cap_permitted;
347 }
348
349 old_cred = override_creds(override_cred);
350retry:
351 res = user_path_at(dfd, filename, lookup_flags, &path);
352 if (res)
353 goto out;
354
355 inode = path.dentry->d_inode;
356
357 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
358 /*
359 * MAY_EXEC on regular files is denied if the fs is mounted
360 * with the "noexec" flag.
361 */
362 res = -EACCES;
363 if (path.mnt->mnt_flags & MNT_NOEXEC)
364 goto out_path_release;
365 }
366
367 res = inode_permission(inode, mode | MAY_ACCESS);
368 /* SuS v2 requires we report a read only fs too */
369 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
370 goto out_path_release;
371 /*
372 * This is a rare case where using __mnt_is_readonly()
373 * is OK without a mnt_want/drop_write() pair. Since
374 * no actual write to the fs is performed here, we do
375 * not need to telegraph to that to anyone.
376 *
377 * By doing this, we accept that this access is
378 * inherently racy and know that the fs may change
379 * state before we even see this result.
380 */
381 if (__mnt_is_readonly(path.mnt))
382 res = -EROFS;
383
384out_path_release:
385 path_put(&path);
386 if (retry_estale(res, lookup_flags)) {
387 lookup_flags |= LOOKUP_REVAL;
388 goto retry;
389 }
390out:
391 revert_creds(old_cred);
392 put_cred(override_cred);
393 return res;
394}
395
396SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
397{
398 return sys_faccessat(AT_FDCWD, filename, mode);
399}
400
401SYSCALL_DEFINE1(chdir, const char __user *, filename)
402{
403 struct path path;
404 int error;
405 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
406retry:
407 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
408 if (error)
409 goto out;
410
411 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
412 if (error)
413 goto dput_and_out;
414
415 set_fs_pwd(current->fs, &path);
416
417dput_and_out:
418 path_put(&path);
419 if (retry_estale(error, lookup_flags)) {
420 lookup_flags |= LOOKUP_REVAL;
421 goto retry;
422 }
423out:
424 return error;
425}
426
427SYSCALL_DEFINE1(fchdir, unsigned int, fd)
428{
429 struct fd f = fdget_raw(fd);
430 struct inode *inode;
431 int error = -EBADF;
432
433 error = -EBADF;
434 if (!f.file)
435 goto out;
436
437 inode = file_inode(f.file);
438
439 error = -ENOTDIR;
440 if (!S_ISDIR(inode->i_mode))
441 goto out_putf;
442
443 error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
444 if (!error)
445 set_fs_pwd(current->fs, &f.file->f_path);
446out_putf:
447 fdput(f);
448out:
449 return error;
450}
451
452SYSCALL_DEFINE1(chroot, const char __user *, filename)
453{
454 struct path path;
455 int error;
456 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
457retry:
458 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
459 if (error)
460 goto out;
461
462 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
463 if (error)
464 goto dput_and_out;
465
466 error = -EPERM;
467 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
468 goto dput_and_out;
469 error = security_path_chroot(&path);
470 if (error)
471 goto dput_and_out;
472
473 set_fs_root(current->fs, &path);
474 error = 0;
475dput_and_out:
476 path_put(&path);
477 if (retry_estale(error, lookup_flags)) {
478 lookup_flags |= LOOKUP_REVAL;
479 goto retry;
480 }
481out:
482 return error;
483}
484
485static int chmod_common(struct path *path, umode_t mode)
486{
487 struct inode *inode = path->dentry->d_inode;
488 struct inode *delegated_inode = NULL;
489 struct iattr newattrs;
490 int error;
491
492 error = mnt_want_write(path->mnt);
493 if (error)
494 return error;
495retry_deleg:
496 mutex_lock(&inode->i_mutex);
497 error = security_path_chmod(path, mode);
498 if (error)
499 goto out_unlock;
500 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
501 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
502 error = notify_change(path->dentry, &newattrs, &delegated_inode);
503out_unlock:
504 mutex_unlock(&inode->i_mutex);
505 if (delegated_inode) {
506 error = break_deleg_wait(&delegated_inode);
507 if (!error)
508 goto retry_deleg;
509 }
510 mnt_drop_write(path->mnt);
511 return error;
512}
513
514SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
515{
516 struct fd f = fdget(fd);
517 int err = -EBADF;
518
519 if (f.file) {
520 audit_inode(NULL, f.file->f_path.dentry, 0);
521 err = chmod_common(&f.file->f_path, mode);
522 fdput(f);
523 }
524 return err;
525}
526
527SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode)
528{
529 struct path path;
530 int error;
531 unsigned int lookup_flags = LOOKUP_FOLLOW;
532retry:
533 error = user_path_at(dfd, filename, lookup_flags, &path);
534 if (!error) {
535 error = chmod_common(&path, mode);
536 path_put(&path);
537 if (retry_estale(error, lookup_flags)) {
538 lookup_flags |= LOOKUP_REVAL;
539 goto retry;
540 }
541 }
542 return error;
543}
544
545SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
546{
547 return sys_fchmodat(AT_FDCWD, filename, mode);
548}
549
550static int chown_common(struct path *path, uid_t user, gid_t group)
551{
552 struct inode *inode = path->dentry->d_inode;
553 struct inode *delegated_inode = NULL;
554 int error;
555 struct iattr newattrs;
556 kuid_t uid;
557 kgid_t gid;
558
559 uid = make_kuid(current_user_ns(), user);
560 gid = make_kgid(current_user_ns(), group);
561
562 newattrs.ia_valid = ATTR_CTIME;
563 if (user != (uid_t) -1) {
564 if (!uid_valid(uid))
565 return -EINVAL;
566 newattrs.ia_valid |= ATTR_UID;
567 newattrs.ia_uid = uid;
568 }
569 if (group != (gid_t) -1) {
570 if (!gid_valid(gid))
571 return -EINVAL;
572 newattrs.ia_valid |= ATTR_GID;
573 newattrs.ia_gid = gid;
574 }
575 if (!S_ISDIR(inode->i_mode))
576 newattrs.ia_valid |=
577 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
578retry_deleg:
579 mutex_lock(&inode->i_mutex);
580 error = security_path_chown(path, uid, gid);
581 if (!error)
582 error = notify_change(path->dentry, &newattrs, &delegated_inode);
583 mutex_unlock(&inode->i_mutex);
584 if (delegated_inode) {
585 error = break_deleg_wait(&delegated_inode);
586 if (!error)
587 goto retry_deleg;
588 }
589 return error;
590}
591
592SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
593 gid_t, group, int, flag)
594{
595 struct path path;
596 int error = -EINVAL;
597 int lookup_flags;
598
599 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
600 goto out;
601
602 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
603 if (flag & AT_EMPTY_PATH)
604 lookup_flags |= LOOKUP_EMPTY;
605retry:
606 error = user_path_at(dfd, filename, lookup_flags, &path);
607 if (error)
608 goto out;
609 error = mnt_want_write(path.mnt);
610 if (error)
611 goto out_release;
612 error = chown_common(&path, user, group);
613 mnt_drop_write(path.mnt);
614out_release:
615 path_put(&path);
616 if (retry_estale(error, lookup_flags)) {
617 lookup_flags |= LOOKUP_REVAL;
618 goto retry;
619 }
620out:
621 return error;
622}
623
624SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
625{
626 return sys_fchownat(AT_FDCWD, filename, user, group, 0);
627}
628
629SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
630{
631 return sys_fchownat(AT_FDCWD, filename, user, group,
632 AT_SYMLINK_NOFOLLOW);
633}
634
635SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
636{
637 struct fd f = fdget(fd);
638 int error = -EBADF;
639
640 if (!f.file)
641 goto out;
642
643 error = mnt_want_write_file(f.file);
644 if (error)
645 goto out_fput;
646 audit_inode(NULL, f.file->f_path.dentry, 0);
647 error = chown_common(&f.file->f_path, user, group);
648 mnt_drop_write_file(f.file);
649out_fput:
650 fdput(f);
651out:
652 return error;
653}
654
655int open_check_o_direct(struct file *f)
656{
657 /* NB: we're sure to have correct a_ops only after f_op->open */
658 if (f->f_flags & O_DIRECT) {
659 if (!f->f_mapping->a_ops ||
660 ((!f->f_mapping->a_ops->direct_IO) &&
661 (!f->f_mapping->a_ops->get_xip_mem))) {
662 return -EINVAL;
663 }
664 }
665 return 0;
666}
667
668static int do_dentry_open(struct file *f,
669 int (*open)(struct inode *, struct file *),
670 const struct cred *cred)
671{
672 static const struct file_operations empty_fops = {};
673 struct inode *inode;
674 int error;
675
676 f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
677 FMODE_PREAD | FMODE_PWRITE;
678
679 path_get(&f->f_path);
680 inode = f->f_inode = f->f_path.dentry->d_inode;
681 f->f_mapping = inode->i_mapping;
682
683 if (unlikely(f->f_flags & O_PATH)) {
684 f->f_mode = FMODE_PATH;
685 f->f_op = &empty_fops;
686 return 0;
687 }
688
689 if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
690 error = get_write_access(inode);
691 if (unlikely(error))
692 goto cleanup_file;
693 error = __mnt_want_write(f->f_path.mnt);
694 if (unlikely(error)) {
695 put_write_access(inode);
696 goto cleanup_file;
697 }
698 f->f_mode |= FMODE_WRITER;
699 }
700
701 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
702 if (S_ISREG(inode->i_mode))
703 f->f_mode |= FMODE_ATOMIC_POS;
704
705 f->f_op = fops_get(inode->i_fop);
706 if (unlikely(WARN_ON(!f->f_op))) {
707 error = -ENODEV;
708 goto cleanup_all;
709 }
710
711 error = security_file_open(f, cred);
712 if (error)
713 goto cleanup_all;
714
715 error = break_lease(inode, f->f_flags);
716 if (error)
717 goto cleanup_all;
718
719 if (!open)
720 open = f->f_op->open;
721 if (open) {
722 error = open(inode, f);
723 if (error)
724 goto cleanup_all;
725 }
726 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
727 i_readcount_inc(inode);
728
729 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
730
731 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
732
733 return 0;
734
735cleanup_all:
736 fops_put(f->f_op);
737 if (f->f_mode & FMODE_WRITER) {
738 put_write_access(inode);
739 __mnt_drop_write(f->f_path.mnt);
740 }
741cleanup_file:
742 path_put(&f->f_path);
743 f->f_path.mnt = NULL;
744 f->f_path.dentry = NULL;
745 f->f_inode = NULL;
746 return error;
747}
748
749/**
750 * finish_open - finish opening a file
751 * @file: file pointer
752 * @dentry: pointer to dentry
753 * @open: open callback
754 * @opened: state of open
755 *
756 * This can be used to finish opening a file passed to i_op->atomic_open().
757 *
758 * If the open callback is set to NULL, then the standard f_op->open()
759 * filesystem callback is substituted.
760 *
761 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
762 * the return value of d_splice_alias(), then the caller needs to perform dput()
763 * on it after finish_open().
764 *
765 * On successful return @file is a fully instantiated open file. After this, if
766 * an error occurs in ->atomic_open(), it needs to clean up with fput().
767 *
768 * Returns zero on success or -errno if the open failed.
769 */
770int finish_open(struct file *file, struct dentry *dentry,
771 int (*open)(struct inode *, struct file *),
772 int *opened)
773{
774 int error;
775 BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
776
777 file->f_path.dentry = dentry;
778 error = do_dentry_open(file, open, current_cred());
779 if (!error)
780 *opened |= FILE_OPENED;
781
782 return error;
783}
784EXPORT_SYMBOL(finish_open);
785
786/**
787 * finish_no_open - finish ->atomic_open() without opening the file
788 *
789 * @file: file pointer
790 * @dentry: dentry or NULL (as returned from ->lookup())
791 *
792 * This can be used to set the result of a successful lookup in ->atomic_open().
793 *
794 * NB: unlike finish_open() this function does consume the dentry reference and
795 * the caller need not dput() it.
796 *
797 * Returns "1" which must be the return value of ->atomic_open() after having
798 * called this function.
799 */
800int finish_no_open(struct file *file, struct dentry *dentry)
801{
802 file->f_path.dentry = dentry;
803 return 1;
804}
805EXPORT_SYMBOL(finish_no_open);
806
807struct file *dentry_open(const struct path *path, int flags,
808 const struct cred *cred)
809{
810 int error;
811 struct file *f;
812
813 validate_creds(cred);
814
815 /* We must always pass in a valid mount pointer. */
816 BUG_ON(!path->mnt);
817
818 f = get_empty_filp();
819 if (!IS_ERR(f)) {
820 f->f_flags = flags;
821 f->f_path = *path;
822 error = do_dentry_open(f, NULL, cred);
823 if (!error) {
824 /* from now on we need fput() to dispose of f */
825 error = open_check_o_direct(f);
826 if (error) {
827 fput(f);
828 f = ERR_PTR(error);
829 }
830 } else {
831 put_filp(f);
832 f = ERR_PTR(error);
833 }
834 }
835 return f;
836}
837EXPORT_SYMBOL(dentry_open);
838
839static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
840{
841 int lookup_flags = 0;
842 int acc_mode;
843
844 if (flags & (O_CREAT | __O_TMPFILE))
845 op->mode = (mode & S_IALLUGO) | S_IFREG;
846 else
847 op->mode = 0;
848
849 /* Must never be set by userspace */
850 flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC;
851
852 /*
853 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
854 * check for O_DSYNC if the need any syncing at all we enforce it's
855 * always set instead of having to deal with possibly weird behaviour
856 * for malicious applications setting only __O_SYNC.
857 */
858 if (flags & __O_SYNC)
859 flags |= O_DSYNC;
860
861 if (flags & __O_TMPFILE) {
862 if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
863 return -EINVAL;
864 acc_mode = MAY_OPEN | ACC_MODE(flags);
865 if (!(acc_mode & MAY_WRITE))
866 return -EINVAL;
867 } else if (flags & O_PATH) {
868 /*
869 * If we have O_PATH in the open flag. Then we
870 * cannot have anything other than the below set of flags
871 */
872 flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
873 acc_mode = 0;
874 } else {
875 acc_mode = MAY_OPEN | ACC_MODE(flags);
876 }
877
878 op->open_flag = flags;
879
880 /* O_TRUNC implies we need access checks for write permissions */
881 if (flags & O_TRUNC)
882 acc_mode |= MAY_WRITE;
883
884 /* Allow the LSM permission hook to distinguish append
885 access from general write access. */
886 if (flags & O_APPEND)
887 acc_mode |= MAY_APPEND;
888
889 op->acc_mode = acc_mode;
890
891 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
892
893 if (flags & O_CREAT) {
894 op->intent |= LOOKUP_CREATE;
895 if (flags & O_EXCL)
896 op->intent |= LOOKUP_EXCL;
897 }
898
899 if (flags & O_DIRECTORY)
900 lookup_flags |= LOOKUP_DIRECTORY;
901 if (!(flags & O_NOFOLLOW))
902 lookup_flags |= LOOKUP_FOLLOW;
903 op->lookup_flags = lookup_flags;
904 return 0;
905}
906
907/**
908 * file_open_name - open file and return file pointer
909 *
910 * @name: struct filename containing path to open
911 * @flags: open flags as per the open(2) second argument
912 * @mode: mode for the new file if O_CREAT is set, else ignored
913 *
914 * This is the helper to open a file from kernelspace if you really
915 * have to. But in generally you should not do this, so please move
916 * along, nothing to see here..
917 */
918struct file *file_open_name(struct filename *name, int flags, umode_t mode)
919{
920 struct open_flags op;
921 int err = build_open_flags(flags, mode, &op);
922 return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &op);
923}
924
925/**
926 * filp_open - open file and return file pointer
927 *
928 * @filename: path to open
929 * @flags: open flags as per the open(2) second argument
930 * @mode: mode for the new file if O_CREAT is set, else ignored
931 *
932 * This is the helper to open a file from kernelspace if you really
933 * have to. But in generally you should not do this, so please move
934 * along, nothing to see here..
935 */
936struct file *filp_open(const char *filename, int flags, umode_t mode)
937{
938 struct filename name = {.name = filename};
939 return file_open_name(&name, flags, mode);
940}
941EXPORT_SYMBOL(filp_open);
942
943struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
944 const char *filename, int flags)
945{
946 struct open_flags op;
947 int err = build_open_flags(flags, 0, &op);
948 if (err)
949 return ERR_PTR(err);
950 if (flags & O_CREAT)
951 return ERR_PTR(-EINVAL);
952 if (!filename && (flags & O_DIRECTORY))
953 if (!dentry->d_inode->i_op->lookup)
954 return ERR_PTR(-ENOTDIR);
955 return do_file_open_root(dentry, mnt, filename, &op);
956}
957EXPORT_SYMBOL(file_open_root);
958
959long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
960{
961 struct open_flags op;
962 int fd = build_open_flags(flags, mode, &op);
963 struct filename *tmp;
964
965 if (fd)
966 return fd;
967
968 tmp = getname(filename);
969 if (IS_ERR(tmp))
970 return PTR_ERR(tmp);
971
972 fd = get_unused_fd_flags(flags);
973 if (fd >= 0) {
974 struct file *f = do_filp_open(dfd, tmp, &op);
975 if (IS_ERR(f)) {
976 put_unused_fd(fd);
977 fd = PTR_ERR(f);
978 } else {
979 fsnotify_open(f);
980 fd_install(fd, f);
981 }
982 }
983 putname(tmp);
984 return fd;
985}
986
987SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
988{
989 if (force_o_largefile())
990 flags |= O_LARGEFILE;
991
992 return do_sys_open(AT_FDCWD, filename, flags, mode);
993}
994
995SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
996 umode_t, mode)
997{
998 if (force_o_largefile())
999 flags |= O_LARGEFILE;
1000
1001 return do_sys_open(dfd, filename, flags, mode);
1002}
1003
1004#ifndef __alpha__
1005
1006/*
1007 * For backward compatibility? Maybe this should be moved
1008 * into arch/i386 instead?
1009 */
1010SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1011{
1012 return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1013}
1014
1015#endif
1016
1017/*
1018 * "id" is the POSIX thread ID. We use the
1019 * files pointer for this..
1020 */
1021int filp_close(struct file *filp, fl_owner_t id)
1022{
1023 int retval = 0;
1024
1025 if (!file_count(filp)) {
1026 printk(KERN_ERR "VFS: Close: file count is 0\n");
1027 return 0;
1028 }
1029
1030 if (filp->f_op->flush)
1031 retval = filp->f_op->flush(filp, id);
1032
1033 if (likely(!(filp->f_mode & FMODE_PATH))) {
1034 dnotify_flush(filp, id);
1035 locks_remove_posix(filp, id);
1036 }
1037 fput(filp);
1038 return retval;
1039}
1040
1041EXPORT_SYMBOL(filp_close);
1042
1043/*
1044 * Careful here! We test whether the file pointer is NULL before
1045 * releasing the fd. This ensures that one clone task can't release
1046 * an fd while another clone is opening it.
1047 */
1048SYSCALL_DEFINE1(close, unsigned int, fd)
1049{
1050 int retval = __close_fd(current->files, fd);
1051
1052 /* can't restart close syscall because file table entry was cleared */
1053 if (unlikely(retval == -ERESTARTSYS ||
1054 retval == -ERESTARTNOINTR ||
1055 retval == -ERESTARTNOHAND ||
1056 retval == -ERESTART_RESTARTBLOCK))
1057 retval = -EINTR;
1058
1059 return retval;
1060}
1061EXPORT_SYMBOL(sys_close);
1062
1063/*
1064 * This routine simulates a hangup on the tty, to arrange that users
1065 * are given clean terminals at login time.
1066 */
1067SYSCALL_DEFINE0(vhangup)
1068{
1069 if (capable(CAP_SYS_TTY_CONFIG)) {
1070 tty_vhangup_self();
1071 return 0;
1072 }
1073 return -EPERM;
1074}
1075
1076/*
1077 * Called when an inode is about to be open.
1078 * We use this to disallow opening large files on 32bit systems if
1079 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1080 * on this flag in sys_open.
1081 */
1082int generic_file_open(struct inode * inode, struct file * filp)
1083{
1084 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1085 return -EOVERFLOW;
1086 return 0;
1087}
1088
1089EXPORT_SYMBOL(generic_file_open);
1090
1091/*
1092 * This is used by subsystems that don't want seekable
1093 * file descriptors. The function is not supposed to ever fail, the only
1094 * reason it returns an 'int' and not 'void' is so that it can be plugged
1095 * directly into file_operations structure.
1096 */
1097int nonseekable_open(struct inode *inode, struct file *filp)
1098{
1099 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1100 return 0;
1101}
1102
1103EXPORT_SYMBOL(nonseekable_open);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/open.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8#include <linux/string.h>
9#include <linux/mm.h>
10#include <linux/file.h>
11#include <linux/fdtable.h>
12#include <linux/fsnotify.h>
13#include <linux/module.h>
14#include <linux/tty.h>
15#include <linux/namei.h>
16#include <linux/backing-dev.h>
17#include <linux/capability.h>
18#include <linux/securebits.h>
19#include <linux/security.h>
20#include <linux/mount.h>
21#include <linux/fcntl.h>
22#include <linux/slab.h>
23#include <linux/uaccess.h>
24#include <linux/fs.h>
25#include <linux/personality.h>
26#include <linux/pagemap.h>
27#include <linux/syscalls.h>
28#include <linux/rcupdate.h>
29#include <linux/audit.h>
30#include <linux/falloc.h>
31#include <linux/fs_struct.h>
32#include <linux/ima.h>
33#include <linux/dnotify.h>
34#include <linux/compat.h>
35
36#include "internal.h"
37
38int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
39 struct file *filp)
40{
41 int ret;
42 struct iattr newattrs;
43
44 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
45 if (length < 0)
46 return -EINVAL;
47
48 newattrs.ia_size = length;
49 newattrs.ia_valid = ATTR_SIZE | time_attrs;
50 if (filp) {
51 newattrs.ia_file = filp;
52 newattrs.ia_valid |= ATTR_FILE;
53 }
54
55 /* Remove suid, sgid, and file capabilities on truncate too */
56 ret = dentry_needs_remove_privs(dentry);
57 if (ret < 0)
58 return ret;
59 if (ret)
60 newattrs.ia_valid |= ret | ATTR_FORCE;
61
62 inode_lock(dentry->d_inode);
63 /* Note any delegations or leases have already been broken: */
64 ret = notify_change(dentry, &newattrs, NULL);
65 inode_unlock(dentry->d_inode);
66 return ret;
67}
68
69long vfs_truncate(const struct path *path, loff_t length)
70{
71 struct inode *inode;
72 long error;
73
74 inode = path->dentry->d_inode;
75
76 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
77 if (S_ISDIR(inode->i_mode))
78 return -EISDIR;
79 if (!S_ISREG(inode->i_mode))
80 return -EINVAL;
81
82 error = mnt_want_write(path->mnt);
83 if (error)
84 goto out;
85
86 error = inode_permission(inode, MAY_WRITE);
87 if (error)
88 goto mnt_drop_write_and_out;
89
90 error = -EPERM;
91 if (IS_APPEND(inode))
92 goto mnt_drop_write_and_out;
93
94 error = get_write_access(inode);
95 if (error)
96 goto mnt_drop_write_and_out;
97
98 /*
99 * Make sure that there are no leases. get_write_access() protects
100 * against the truncate racing with a lease-granting setlease().
101 */
102 error = break_lease(inode, O_WRONLY);
103 if (error)
104 goto put_write_and_out;
105
106 error = locks_verify_truncate(inode, NULL, length);
107 if (!error)
108 error = security_path_truncate(path);
109 if (!error)
110 error = do_truncate(path->dentry, length, 0, NULL);
111
112put_write_and_out:
113 put_write_access(inode);
114mnt_drop_write_and_out:
115 mnt_drop_write(path->mnt);
116out:
117 return error;
118}
119EXPORT_SYMBOL_GPL(vfs_truncate);
120
121long do_sys_truncate(const char __user *pathname, loff_t length)
122{
123 unsigned int lookup_flags = LOOKUP_FOLLOW;
124 struct path path;
125 int error;
126
127 if (length < 0) /* sorry, but loff_t says... */
128 return -EINVAL;
129
130retry:
131 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
132 if (!error) {
133 error = vfs_truncate(&path, length);
134 path_put(&path);
135 }
136 if (retry_estale(error, lookup_flags)) {
137 lookup_flags |= LOOKUP_REVAL;
138 goto retry;
139 }
140 return error;
141}
142
143SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
144{
145 return do_sys_truncate(path, length);
146}
147
148#ifdef CONFIG_COMPAT
149COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
150{
151 return do_sys_truncate(path, length);
152}
153#endif
154
155long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
156{
157 struct inode *inode;
158 struct dentry *dentry;
159 struct fd f;
160 int error;
161
162 error = -EINVAL;
163 if (length < 0)
164 goto out;
165 error = -EBADF;
166 f = fdget(fd);
167 if (!f.file)
168 goto out;
169
170 /* explicitly opened as large or we are on 64-bit box */
171 if (f.file->f_flags & O_LARGEFILE)
172 small = 0;
173
174 dentry = f.file->f_path.dentry;
175 inode = dentry->d_inode;
176 error = -EINVAL;
177 if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
178 goto out_putf;
179
180 error = -EINVAL;
181 /* Cannot ftruncate over 2^31 bytes without large file support */
182 if (small && length > MAX_NON_LFS)
183 goto out_putf;
184
185 error = -EPERM;
186 /* Check IS_APPEND on real upper inode */
187 if (IS_APPEND(file_inode(f.file)))
188 goto out_putf;
189
190 sb_start_write(inode->i_sb);
191 error = locks_verify_truncate(inode, f.file, length);
192 if (!error)
193 error = security_path_truncate(&f.file->f_path);
194 if (!error)
195 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
196 sb_end_write(inode->i_sb);
197out_putf:
198 fdput(f);
199out:
200 return error;
201}
202
203SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
204{
205 return do_sys_ftruncate(fd, length, 1);
206}
207
208#ifdef CONFIG_COMPAT
209COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
210{
211 return do_sys_ftruncate(fd, length, 1);
212}
213#endif
214
215/* LFS versions of truncate are only needed on 32 bit machines */
216#if BITS_PER_LONG == 32
217SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
218{
219 return do_sys_truncate(path, length);
220}
221
222SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
223{
224 return do_sys_ftruncate(fd, length, 0);
225}
226#endif /* BITS_PER_LONG == 32 */
227
228
229int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
230{
231 struct inode *inode = file_inode(file);
232 long ret;
233
234 if (offset < 0 || len <= 0)
235 return -EINVAL;
236
237 /* Return error if mode is not supported */
238 if (mode & ~FALLOC_FL_SUPPORTED_MASK)
239 return -EOPNOTSUPP;
240
241 /* Punch hole and zero range are mutually exclusive */
242 if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
243 (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
244 return -EOPNOTSUPP;
245
246 /* Punch hole must have keep size set */
247 if ((mode & FALLOC_FL_PUNCH_HOLE) &&
248 !(mode & FALLOC_FL_KEEP_SIZE))
249 return -EOPNOTSUPP;
250
251 /* Collapse range should only be used exclusively. */
252 if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
253 (mode & ~FALLOC_FL_COLLAPSE_RANGE))
254 return -EINVAL;
255
256 /* Insert range should only be used exclusively. */
257 if ((mode & FALLOC_FL_INSERT_RANGE) &&
258 (mode & ~FALLOC_FL_INSERT_RANGE))
259 return -EINVAL;
260
261 /* Unshare range should only be used with allocate mode. */
262 if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
263 (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
264 return -EINVAL;
265
266 if (!(file->f_mode & FMODE_WRITE))
267 return -EBADF;
268
269 /*
270 * We can only allow pure fallocate on append only files
271 */
272 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
273 return -EPERM;
274
275 if (IS_IMMUTABLE(inode))
276 return -EPERM;
277
278 /*
279 * We cannot allow any fallocate operation on an active swapfile
280 */
281 if (IS_SWAPFILE(inode))
282 return -ETXTBSY;
283
284 /*
285 * Revalidate the write permissions, in case security policy has
286 * changed since the files were opened.
287 */
288 ret = security_file_permission(file, MAY_WRITE);
289 if (ret)
290 return ret;
291
292 if (S_ISFIFO(inode->i_mode))
293 return -ESPIPE;
294
295 if (S_ISDIR(inode->i_mode))
296 return -EISDIR;
297
298 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
299 return -ENODEV;
300
301 /* Check for wrap through zero too */
302 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
303 return -EFBIG;
304
305 if (!file->f_op->fallocate)
306 return -EOPNOTSUPP;
307
308 file_start_write(file);
309 ret = file->f_op->fallocate(file, mode, offset, len);
310
311 /*
312 * Create inotify and fanotify events.
313 *
314 * To keep the logic simple always create events if fallocate succeeds.
315 * This implies that events are even created if the file size remains
316 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
317 */
318 if (ret == 0)
319 fsnotify_modify(file);
320
321 file_end_write(file);
322 return ret;
323}
324EXPORT_SYMBOL_GPL(vfs_fallocate);
325
326int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
327{
328 struct fd f = fdget(fd);
329 int error = -EBADF;
330
331 if (f.file) {
332 error = vfs_fallocate(f.file, mode, offset, len);
333 fdput(f);
334 }
335 return error;
336}
337
338SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
339{
340 return ksys_fallocate(fd, mode, offset, len);
341}
342
343/*
344 * access() needs to use the real uid/gid, not the effective uid/gid.
345 * We do this by temporarily clearing all FS-related capabilities and
346 * switching the fsuid/fsgid around to the real ones.
347 */
348long do_faccessat(int dfd, const char __user *filename, int mode)
349{
350 const struct cred *old_cred;
351 struct cred *override_cred;
352 struct path path;
353 struct inode *inode;
354 int res;
355 unsigned int lookup_flags = LOOKUP_FOLLOW;
356
357 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
358 return -EINVAL;
359
360 override_cred = prepare_creds();
361 if (!override_cred)
362 return -ENOMEM;
363
364 override_cred->fsuid = override_cred->uid;
365 override_cred->fsgid = override_cred->gid;
366
367 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
368 /* Clear the capabilities if we switch to a non-root user */
369 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
370 if (!uid_eq(override_cred->uid, root_uid))
371 cap_clear(override_cred->cap_effective);
372 else
373 override_cred->cap_effective =
374 override_cred->cap_permitted;
375 }
376
377 /*
378 * The new set of credentials can *only* be used in
379 * task-synchronous circumstances, and does not need
380 * RCU freeing, unless somebody then takes a separate
381 * reference to it.
382 *
383 * NOTE! This is _only_ true because this credential
384 * is used purely for override_creds() that installs
385 * it as the subjective cred. Other threads will be
386 * accessing ->real_cred, not the subjective cred.
387 *
388 * If somebody _does_ make a copy of this (using the
389 * 'get_current_cred()' function), that will clear the
390 * non_rcu field, because now that other user may be
391 * expecting RCU freeing. But normal thread-synchronous
392 * cred accesses will keep things non-RCY.
393 */
394 override_cred->non_rcu = 1;
395
396 old_cred = override_creds(override_cred);
397retry:
398 res = user_path_at(dfd, filename, lookup_flags, &path);
399 if (res)
400 goto out;
401
402 inode = d_backing_inode(path.dentry);
403
404 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
405 /*
406 * MAY_EXEC on regular files is denied if the fs is mounted
407 * with the "noexec" flag.
408 */
409 res = -EACCES;
410 if (path_noexec(&path))
411 goto out_path_release;
412 }
413
414 res = inode_permission(inode, mode | MAY_ACCESS);
415 /* SuS v2 requires we report a read only fs too */
416 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
417 goto out_path_release;
418 /*
419 * This is a rare case where using __mnt_is_readonly()
420 * is OK without a mnt_want/drop_write() pair. Since
421 * no actual write to the fs is performed here, we do
422 * not need to telegraph to that to anyone.
423 *
424 * By doing this, we accept that this access is
425 * inherently racy and know that the fs may change
426 * state before we even see this result.
427 */
428 if (__mnt_is_readonly(path.mnt))
429 res = -EROFS;
430
431out_path_release:
432 path_put(&path);
433 if (retry_estale(res, lookup_flags)) {
434 lookup_flags |= LOOKUP_REVAL;
435 goto retry;
436 }
437out:
438 revert_creds(old_cred);
439 put_cred(override_cred);
440 return res;
441}
442
443SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
444{
445 return do_faccessat(dfd, filename, mode);
446}
447
448SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
449{
450 return do_faccessat(AT_FDCWD, filename, mode);
451}
452
453int ksys_chdir(const char __user *filename)
454{
455 struct path path;
456 int error;
457 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
458retry:
459 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
460 if (error)
461 goto out;
462
463 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
464 if (error)
465 goto dput_and_out;
466
467 set_fs_pwd(current->fs, &path);
468
469dput_and_out:
470 path_put(&path);
471 if (retry_estale(error, lookup_flags)) {
472 lookup_flags |= LOOKUP_REVAL;
473 goto retry;
474 }
475out:
476 return error;
477}
478
479SYSCALL_DEFINE1(chdir, const char __user *, filename)
480{
481 return ksys_chdir(filename);
482}
483
484SYSCALL_DEFINE1(fchdir, unsigned int, fd)
485{
486 struct fd f = fdget_raw(fd);
487 int error;
488
489 error = -EBADF;
490 if (!f.file)
491 goto out;
492
493 error = -ENOTDIR;
494 if (!d_can_lookup(f.file->f_path.dentry))
495 goto out_putf;
496
497 error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
498 if (!error)
499 set_fs_pwd(current->fs, &f.file->f_path);
500out_putf:
501 fdput(f);
502out:
503 return error;
504}
505
506int ksys_chroot(const char __user *filename)
507{
508 struct path path;
509 int error;
510 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
511retry:
512 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
513 if (error)
514 goto out;
515
516 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
517 if (error)
518 goto dput_and_out;
519
520 error = -EPERM;
521 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
522 goto dput_and_out;
523 error = security_path_chroot(&path);
524 if (error)
525 goto dput_and_out;
526
527 set_fs_root(current->fs, &path);
528 error = 0;
529dput_and_out:
530 path_put(&path);
531 if (retry_estale(error, lookup_flags)) {
532 lookup_flags |= LOOKUP_REVAL;
533 goto retry;
534 }
535out:
536 return error;
537}
538
539SYSCALL_DEFINE1(chroot, const char __user *, filename)
540{
541 return ksys_chroot(filename);
542}
543
544static int chmod_common(const struct path *path, umode_t mode)
545{
546 struct inode *inode = path->dentry->d_inode;
547 struct inode *delegated_inode = NULL;
548 struct iattr newattrs;
549 int error;
550
551 error = mnt_want_write(path->mnt);
552 if (error)
553 return error;
554retry_deleg:
555 inode_lock(inode);
556 error = security_path_chmod(path, mode);
557 if (error)
558 goto out_unlock;
559 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
560 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
561 error = notify_change(path->dentry, &newattrs, &delegated_inode);
562out_unlock:
563 inode_unlock(inode);
564 if (delegated_inode) {
565 error = break_deleg_wait(&delegated_inode);
566 if (!error)
567 goto retry_deleg;
568 }
569 mnt_drop_write(path->mnt);
570 return error;
571}
572
573int ksys_fchmod(unsigned int fd, umode_t mode)
574{
575 struct fd f = fdget(fd);
576 int err = -EBADF;
577
578 if (f.file) {
579 audit_file(f.file);
580 err = chmod_common(&f.file->f_path, mode);
581 fdput(f);
582 }
583 return err;
584}
585
586SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
587{
588 return ksys_fchmod(fd, mode);
589}
590
591int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
592{
593 struct path path;
594 int error;
595 unsigned int lookup_flags = LOOKUP_FOLLOW;
596retry:
597 error = user_path_at(dfd, filename, lookup_flags, &path);
598 if (!error) {
599 error = chmod_common(&path, mode);
600 path_put(&path);
601 if (retry_estale(error, lookup_flags)) {
602 lookup_flags |= LOOKUP_REVAL;
603 goto retry;
604 }
605 }
606 return error;
607}
608
609SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
610 umode_t, mode)
611{
612 return do_fchmodat(dfd, filename, mode);
613}
614
615SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
616{
617 return do_fchmodat(AT_FDCWD, filename, mode);
618}
619
620static int chown_common(const struct path *path, uid_t user, gid_t group)
621{
622 struct inode *inode = path->dentry->d_inode;
623 struct inode *delegated_inode = NULL;
624 int error;
625 struct iattr newattrs;
626 kuid_t uid;
627 kgid_t gid;
628
629 uid = make_kuid(current_user_ns(), user);
630 gid = make_kgid(current_user_ns(), group);
631
632retry_deleg:
633 newattrs.ia_valid = ATTR_CTIME;
634 if (user != (uid_t) -1) {
635 if (!uid_valid(uid))
636 return -EINVAL;
637 newattrs.ia_valid |= ATTR_UID;
638 newattrs.ia_uid = uid;
639 }
640 if (group != (gid_t) -1) {
641 if (!gid_valid(gid))
642 return -EINVAL;
643 newattrs.ia_valid |= ATTR_GID;
644 newattrs.ia_gid = gid;
645 }
646 if (!S_ISDIR(inode->i_mode))
647 newattrs.ia_valid |=
648 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
649 inode_lock(inode);
650 error = security_path_chown(path, uid, gid);
651 if (!error)
652 error = notify_change(path->dentry, &newattrs, &delegated_inode);
653 inode_unlock(inode);
654 if (delegated_inode) {
655 error = break_deleg_wait(&delegated_inode);
656 if (!error)
657 goto retry_deleg;
658 }
659 return error;
660}
661
662int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
663 int flag)
664{
665 struct path path;
666 int error = -EINVAL;
667 int lookup_flags;
668
669 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
670 goto out;
671
672 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
673 if (flag & AT_EMPTY_PATH)
674 lookup_flags |= LOOKUP_EMPTY;
675retry:
676 error = user_path_at(dfd, filename, lookup_flags, &path);
677 if (error)
678 goto out;
679 error = mnt_want_write(path.mnt);
680 if (error)
681 goto out_release;
682 error = chown_common(&path, user, group);
683 mnt_drop_write(path.mnt);
684out_release:
685 path_put(&path);
686 if (retry_estale(error, lookup_flags)) {
687 lookup_flags |= LOOKUP_REVAL;
688 goto retry;
689 }
690out:
691 return error;
692}
693
694SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
695 gid_t, group, int, flag)
696{
697 return do_fchownat(dfd, filename, user, group, flag);
698}
699
700SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
701{
702 return do_fchownat(AT_FDCWD, filename, user, group, 0);
703}
704
705SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
706{
707 return do_fchownat(AT_FDCWD, filename, user, group,
708 AT_SYMLINK_NOFOLLOW);
709}
710
711int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
712{
713 struct fd f = fdget(fd);
714 int error = -EBADF;
715
716 if (!f.file)
717 goto out;
718
719 error = mnt_want_write_file(f.file);
720 if (error)
721 goto out_fput;
722 audit_file(f.file);
723 error = chown_common(&f.file->f_path, user, group);
724 mnt_drop_write_file(f.file);
725out_fput:
726 fdput(f);
727out:
728 return error;
729}
730
731SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
732{
733 return ksys_fchown(fd, user, group);
734}
735
736static int do_dentry_open(struct file *f,
737 struct inode *inode,
738 int (*open)(struct inode *, struct file *))
739{
740 static const struct file_operations empty_fops = {};
741 int error;
742
743 path_get(&f->f_path);
744 f->f_inode = inode;
745 f->f_mapping = inode->i_mapping;
746
747 /* Ensure that we skip any errors that predate opening of the file */
748 f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
749
750 if (unlikely(f->f_flags & O_PATH)) {
751 f->f_mode = FMODE_PATH | FMODE_OPENED;
752 f->f_op = &empty_fops;
753 return 0;
754 }
755
756 /* Any file opened for execve()/uselib() has to be a regular file. */
757 if (unlikely(f->f_flags & FMODE_EXEC && !S_ISREG(inode->i_mode))) {
758 error = -EACCES;
759 goto cleanup_file;
760 }
761
762 if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
763 error = get_write_access(inode);
764 if (unlikely(error))
765 goto cleanup_file;
766 error = __mnt_want_write(f->f_path.mnt);
767 if (unlikely(error)) {
768 put_write_access(inode);
769 goto cleanup_file;
770 }
771 f->f_mode |= FMODE_WRITER;
772 }
773
774 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
775 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
776 f->f_mode |= FMODE_ATOMIC_POS;
777
778 f->f_op = fops_get(inode->i_fop);
779 if (WARN_ON(!f->f_op)) {
780 error = -ENODEV;
781 goto cleanup_all;
782 }
783
784 error = security_file_open(f);
785 if (error)
786 goto cleanup_all;
787
788 error = break_lease(locks_inode(f), f->f_flags);
789 if (error)
790 goto cleanup_all;
791
792 /* normally all 3 are set; ->open() can clear them if needed */
793 f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
794 if (!open)
795 open = f->f_op->open;
796 if (open) {
797 error = open(inode, f);
798 if (error)
799 goto cleanup_all;
800 }
801 f->f_mode |= FMODE_OPENED;
802 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
803 i_readcount_inc(inode);
804 if ((f->f_mode & FMODE_READ) &&
805 likely(f->f_op->read || f->f_op->read_iter))
806 f->f_mode |= FMODE_CAN_READ;
807 if ((f->f_mode & FMODE_WRITE) &&
808 likely(f->f_op->write || f->f_op->write_iter))
809 f->f_mode |= FMODE_CAN_WRITE;
810
811 f->f_write_hint = WRITE_LIFE_NOT_SET;
812 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
813
814 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
815
816 /* NB: we're sure to have correct a_ops only after f_op->open */
817 if (f->f_flags & O_DIRECT) {
818 if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
819 return -EINVAL;
820 }
821
822 /*
823 * XXX: Huge page cache doesn't support writing yet. Drop all page
824 * cache for this file before processing writes.
825 */
826 if ((f->f_mode & FMODE_WRITE) && filemap_nr_thps(inode->i_mapping))
827 truncate_pagecache(inode, 0);
828
829 return 0;
830
831cleanup_all:
832 if (WARN_ON_ONCE(error > 0))
833 error = -EINVAL;
834 fops_put(f->f_op);
835 if (f->f_mode & FMODE_WRITER) {
836 put_write_access(inode);
837 __mnt_drop_write(f->f_path.mnt);
838 }
839cleanup_file:
840 path_put(&f->f_path);
841 f->f_path.mnt = NULL;
842 f->f_path.dentry = NULL;
843 f->f_inode = NULL;
844 return error;
845}
846
847/**
848 * finish_open - finish opening a file
849 * @file: file pointer
850 * @dentry: pointer to dentry
851 * @open: open callback
852 * @opened: state of open
853 *
854 * This can be used to finish opening a file passed to i_op->atomic_open().
855 *
856 * If the open callback is set to NULL, then the standard f_op->open()
857 * filesystem callback is substituted.
858 *
859 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
860 * the return value of d_splice_alias(), then the caller needs to perform dput()
861 * on it after finish_open().
862 *
863 * On successful return @file is a fully instantiated open file. After this, if
864 * an error occurs in ->atomic_open(), it needs to clean up with fput().
865 *
866 * Returns zero on success or -errno if the open failed.
867 */
868int finish_open(struct file *file, struct dentry *dentry,
869 int (*open)(struct inode *, struct file *))
870{
871 BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
872
873 file->f_path.dentry = dentry;
874 return do_dentry_open(file, d_backing_inode(dentry), open);
875}
876EXPORT_SYMBOL(finish_open);
877
878/**
879 * finish_no_open - finish ->atomic_open() without opening the file
880 *
881 * @file: file pointer
882 * @dentry: dentry or NULL (as returned from ->lookup())
883 *
884 * This can be used to set the result of a successful lookup in ->atomic_open().
885 *
886 * NB: unlike finish_open() this function does consume the dentry reference and
887 * the caller need not dput() it.
888 *
889 * Returns "0" which must be the return value of ->atomic_open() after having
890 * called this function.
891 */
892int finish_no_open(struct file *file, struct dentry *dentry)
893{
894 file->f_path.dentry = dentry;
895 return 0;
896}
897EXPORT_SYMBOL(finish_no_open);
898
899char *file_path(struct file *filp, char *buf, int buflen)
900{
901 return d_path(&filp->f_path, buf, buflen);
902}
903EXPORT_SYMBOL(file_path);
904
905/**
906 * vfs_open - open the file at the given path
907 * @path: path to open
908 * @file: newly allocated file with f_flag initialized
909 * @cred: credentials to use
910 */
911int vfs_open(const struct path *path, struct file *file)
912{
913 file->f_path = *path;
914 return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
915}
916
917struct file *dentry_open(const struct path *path, int flags,
918 const struct cred *cred)
919{
920 int error;
921 struct file *f;
922
923 validate_creds(cred);
924
925 /* We must always pass in a valid mount pointer. */
926 BUG_ON(!path->mnt);
927
928 f = alloc_empty_file(flags, cred);
929 if (!IS_ERR(f)) {
930 error = vfs_open(path, f);
931 if (error) {
932 fput(f);
933 f = ERR_PTR(error);
934 }
935 }
936 return f;
937}
938EXPORT_SYMBOL(dentry_open);
939
940struct file *open_with_fake_path(const struct path *path, int flags,
941 struct inode *inode, const struct cred *cred)
942{
943 struct file *f = alloc_empty_file_noaccount(flags, cred);
944 if (!IS_ERR(f)) {
945 int error;
946
947 f->f_path = *path;
948 error = do_dentry_open(f, inode, NULL);
949 if (error) {
950 fput(f);
951 f = ERR_PTR(error);
952 }
953 }
954 return f;
955}
956EXPORT_SYMBOL(open_with_fake_path);
957
958static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
959{
960 int lookup_flags = 0;
961 int acc_mode = ACC_MODE(flags);
962
963 /*
964 * Clear out all open flags we don't know about so that we don't report
965 * them in fcntl(F_GETFD) or similar interfaces.
966 */
967 flags &= VALID_OPEN_FLAGS;
968
969 if (flags & (O_CREAT | __O_TMPFILE))
970 op->mode = (mode & S_IALLUGO) | S_IFREG;
971 else
972 op->mode = 0;
973
974 /* Must never be set by userspace */
975 flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC;
976
977 /*
978 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
979 * check for O_DSYNC if the need any syncing at all we enforce it's
980 * always set instead of having to deal with possibly weird behaviour
981 * for malicious applications setting only __O_SYNC.
982 */
983 if (flags & __O_SYNC)
984 flags |= O_DSYNC;
985
986 if (flags & __O_TMPFILE) {
987 if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
988 return -EINVAL;
989 if (!(acc_mode & MAY_WRITE))
990 return -EINVAL;
991 } else if (flags & O_PATH) {
992 /*
993 * If we have O_PATH in the open flag. Then we
994 * cannot have anything other than the below set of flags
995 */
996 flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
997 acc_mode = 0;
998 }
999
1000 op->open_flag = flags;
1001
1002 /* O_TRUNC implies we need access checks for write permissions */
1003 if (flags & O_TRUNC)
1004 acc_mode |= MAY_WRITE;
1005
1006 /* Allow the LSM permission hook to distinguish append
1007 access from general write access. */
1008 if (flags & O_APPEND)
1009 acc_mode |= MAY_APPEND;
1010
1011 op->acc_mode = acc_mode;
1012
1013 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1014
1015 if (flags & O_CREAT) {
1016 op->intent |= LOOKUP_CREATE;
1017 if (flags & O_EXCL)
1018 op->intent |= LOOKUP_EXCL;
1019 }
1020
1021 if (flags & O_DIRECTORY)
1022 lookup_flags |= LOOKUP_DIRECTORY;
1023 if (!(flags & O_NOFOLLOW))
1024 lookup_flags |= LOOKUP_FOLLOW;
1025 op->lookup_flags = lookup_flags;
1026 return 0;
1027}
1028
1029/**
1030 * file_open_name - open file and return file pointer
1031 *
1032 * @name: struct filename containing path to open
1033 * @flags: open flags as per the open(2) second argument
1034 * @mode: mode for the new file if O_CREAT is set, else ignored
1035 *
1036 * This is the helper to open a file from kernelspace if you really
1037 * have to. But in generally you should not do this, so please move
1038 * along, nothing to see here..
1039 */
1040struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1041{
1042 struct open_flags op;
1043 int err = build_open_flags(flags, mode, &op);
1044 return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &op);
1045}
1046
1047/**
1048 * filp_open - open file and return file pointer
1049 *
1050 * @filename: path to open
1051 * @flags: open flags as per the open(2) second argument
1052 * @mode: mode for the new file if O_CREAT is set, else ignored
1053 *
1054 * This is the helper to open a file from kernelspace if you really
1055 * have to. But in generally you should not do this, so please move
1056 * along, nothing to see here..
1057 */
1058struct file *filp_open(const char *filename, int flags, umode_t mode)
1059{
1060 struct filename *name = getname_kernel(filename);
1061 struct file *file = ERR_CAST(name);
1062
1063 if (!IS_ERR(name)) {
1064 file = file_open_name(name, flags, mode);
1065 putname(name);
1066 }
1067 return file;
1068}
1069EXPORT_SYMBOL(filp_open);
1070
1071struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
1072 const char *filename, int flags, umode_t mode)
1073{
1074 struct open_flags op;
1075 int err = build_open_flags(flags, mode, &op);
1076 if (err)
1077 return ERR_PTR(err);
1078 return do_file_open_root(dentry, mnt, filename, &op);
1079}
1080EXPORT_SYMBOL(file_open_root);
1081
1082long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1083{
1084 struct open_flags op;
1085 int fd = build_open_flags(flags, mode, &op);
1086 struct filename *tmp;
1087
1088 if (fd)
1089 return fd;
1090
1091 tmp = getname(filename);
1092 if (IS_ERR(tmp))
1093 return PTR_ERR(tmp);
1094
1095 fd = get_unused_fd_flags(flags);
1096 if (fd >= 0) {
1097 struct file *f = do_filp_open(dfd, tmp, &op);
1098 if (IS_ERR(f)) {
1099 put_unused_fd(fd);
1100 fd = PTR_ERR(f);
1101 } else {
1102 fsnotify_open(f);
1103 fd_install(fd, f);
1104 }
1105 }
1106 putname(tmp);
1107 return fd;
1108}
1109
1110SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1111{
1112 if (force_o_largefile())
1113 flags |= O_LARGEFILE;
1114
1115 return do_sys_open(AT_FDCWD, filename, flags, mode);
1116}
1117
1118SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1119 umode_t, mode)
1120{
1121 if (force_o_largefile())
1122 flags |= O_LARGEFILE;
1123
1124 return do_sys_open(dfd, filename, flags, mode);
1125}
1126
1127#ifdef CONFIG_COMPAT
1128/*
1129 * Exactly like sys_open(), except that it doesn't set the
1130 * O_LARGEFILE flag.
1131 */
1132COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1133{
1134 return do_sys_open(AT_FDCWD, filename, flags, mode);
1135}
1136
1137/*
1138 * Exactly like sys_openat(), except that it doesn't set the
1139 * O_LARGEFILE flag.
1140 */
1141COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1142{
1143 return do_sys_open(dfd, filename, flags, mode);
1144}
1145#endif
1146
1147#ifndef __alpha__
1148
1149/*
1150 * For backward compatibility? Maybe this should be moved
1151 * into arch/i386 instead?
1152 */
1153SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1154{
1155 return ksys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1156}
1157
1158#endif
1159
1160/*
1161 * "id" is the POSIX thread ID. We use the
1162 * files pointer for this..
1163 */
1164int filp_close(struct file *filp, fl_owner_t id)
1165{
1166 int retval = 0;
1167
1168 if (!file_count(filp)) {
1169 printk(KERN_ERR "VFS: Close: file count is 0\n");
1170 return 0;
1171 }
1172
1173 if (filp->f_op->flush)
1174 retval = filp->f_op->flush(filp, id);
1175
1176 if (likely(!(filp->f_mode & FMODE_PATH))) {
1177 dnotify_flush(filp, id);
1178 locks_remove_posix(filp, id);
1179 }
1180 fput(filp);
1181 return retval;
1182}
1183
1184EXPORT_SYMBOL(filp_close);
1185
1186/*
1187 * Careful here! We test whether the file pointer is NULL before
1188 * releasing the fd. This ensures that one clone task can't release
1189 * an fd while another clone is opening it.
1190 */
1191SYSCALL_DEFINE1(close, unsigned int, fd)
1192{
1193 int retval = __close_fd(current->files, fd);
1194
1195 /* can't restart close syscall because file table entry was cleared */
1196 if (unlikely(retval == -ERESTARTSYS ||
1197 retval == -ERESTARTNOINTR ||
1198 retval == -ERESTARTNOHAND ||
1199 retval == -ERESTART_RESTARTBLOCK))
1200 retval = -EINTR;
1201
1202 return retval;
1203}
1204
1205/*
1206 * This routine simulates a hangup on the tty, to arrange that users
1207 * are given clean terminals at login time.
1208 */
1209SYSCALL_DEFINE0(vhangup)
1210{
1211 if (capable(CAP_SYS_TTY_CONFIG)) {
1212 tty_vhangup_self();
1213 return 0;
1214 }
1215 return -EPERM;
1216}
1217
1218/*
1219 * Called when an inode is about to be open.
1220 * We use this to disallow opening large files on 32bit systems if
1221 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1222 * on this flag in sys_open.
1223 */
1224int generic_file_open(struct inode * inode, struct file * filp)
1225{
1226 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1227 return -EOVERFLOW;
1228 return 0;
1229}
1230
1231EXPORT_SYMBOL(generic_file_open);
1232
1233/*
1234 * This is used by subsystems that don't want seekable
1235 * file descriptors. The function is not supposed to ever fail, the only
1236 * reason it returns an 'int' and not 'void' is so that it can be plugged
1237 * directly into file_operations structure.
1238 */
1239int nonseekable_open(struct inode *inode, struct file *filp)
1240{
1241 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1242 return 0;
1243}
1244
1245EXPORT_SYMBOL(nonseekable_open);
1246
1247/*
1248 * stream_open is used by subsystems that want stream-like file descriptors.
1249 * Such file descriptors are not seekable and don't have notion of position
1250 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1251 * Contrary to file descriptors of other regular files, .read() and .write()
1252 * can run simultaneously.
1253 *
1254 * stream_open never fails and is marked to return int so that it could be
1255 * directly used as file_operations.open .
1256 */
1257int stream_open(struct inode *inode, struct file *filp)
1258{
1259 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1260 filp->f_mode |= FMODE_STREAM;
1261 return 0;
1262}
1263
1264EXPORT_SYMBOL(stream_open);