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