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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 */
348static const struct cred *access_override_creds(void)
349{
350 const struct cred *old_cred;
351 struct cred *override_cred;
352
353 override_cred = prepare_creds();
354 if (!override_cred)
355 return NULL;
356
357 override_cred->fsuid = override_cred->uid;
358 override_cred->fsgid = override_cred->gid;
359
360 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
361 /* Clear the capabilities if we switch to a non-root user */
362 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
363 if (!uid_eq(override_cred->uid, root_uid))
364 cap_clear(override_cred->cap_effective);
365 else
366 override_cred->cap_effective =
367 override_cred->cap_permitted;
368 }
369
370 /*
371 * The new set of credentials can *only* be used in
372 * task-synchronous circumstances, and does not need
373 * RCU freeing, unless somebody then takes a separate
374 * reference to it.
375 *
376 * NOTE! This is _only_ true because this credential
377 * is used purely for override_creds() that installs
378 * it as the subjective cred. Other threads will be
379 * accessing ->real_cred, not the subjective cred.
380 *
381 * If somebody _does_ make a copy of this (using the
382 * 'get_current_cred()' function), that will clear the
383 * non_rcu field, because now that other user may be
384 * expecting RCU freeing. But normal thread-synchronous
385 * cred accesses will keep things non-RCY.
386 */
387 override_cred->non_rcu = 1;
388
389 old_cred = override_creds(override_cred);
390
391 /* override_cred() gets its own ref */
392 put_cred(override_cred);
393
394 return old_cred;
395}
396
397static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
398{
399 struct path path;
400 struct inode *inode;
401 int res;
402 unsigned int lookup_flags = LOOKUP_FOLLOW;
403 const struct cred *old_cred = NULL;
404
405 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
406 return -EINVAL;
407
408 if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
409 return -EINVAL;
410
411 if (flags & AT_SYMLINK_NOFOLLOW)
412 lookup_flags &= ~LOOKUP_FOLLOW;
413 if (flags & AT_EMPTY_PATH)
414 lookup_flags |= LOOKUP_EMPTY;
415
416 if (!(flags & AT_EACCESS)) {
417 old_cred = access_override_creds();
418 if (!old_cred)
419 return -ENOMEM;
420 }
421
422retry:
423 res = user_path_at(dfd, filename, lookup_flags, &path);
424 if (res)
425 goto out;
426
427 inode = d_backing_inode(path.dentry);
428
429 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
430 /*
431 * MAY_EXEC on regular files is denied if the fs is mounted
432 * with the "noexec" flag.
433 */
434 res = -EACCES;
435 if (path_noexec(&path))
436 goto out_path_release;
437 }
438
439 res = inode_permission(inode, mode | MAY_ACCESS);
440 /* SuS v2 requires we report a read only fs too */
441 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
442 goto out_path_release;
443 /*
444 * This is a rare case where using __mnt_is_readonly()
445 * is OK without a mnt_want/drop_write() pair. Since
446 * no actual write to the fs is performed here, we do
447 * not need to telegraph to that to anyone.
448 *
449 * By doing this, we accept that this access is
450 * inherently racy and know that the fs may change
451 * state before we even see this result.
452 */
453 if (__mnt_is_readonly(path.mnt))
454 res = -EROFS;
455
456out_path_release:
457 path_put(&path);
458 if (retry_estale(res, lookup_flags)) {
459 lookup_flags |= LOOKUP_REVAL;
460 goto retry;
461 }
462out:
463 if (old_cred)
464 revert_creds(old_cred);
465
466 return res;
467}
468
469SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
470{
471 return do_faccessat(dfd, filename, mode, 0);
472}
473
474SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
475 int, flags)
476{
477 return do_faccessat(dfd, filename, mode, flags);
478}
479
480SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
481{
482 return do_faccessat(AT_FDCWD, filename, mode, 0);
483}
484
485SYSCALL_DEFINE1(chdir, const char __user *, filename)
486{
487 struct path path;
488 int error;
489 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
490retry:
491 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
492 if (error)
493 goto out;
494
495 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
496 if (error)
497 goto dput_and_out;
498
499 set_fs_pwd(current->fs, &path);
500
501dput_and_out:
502 path_put(&path);
503 if (retry_estale(error, lookup_flags)) {
504 lookup_flags |= LOOKUP_REVAL;
505 goto retry;
506 }
507out:
508 return error;
509}
510
511SYSCALL_DEFINE1(fchdir, unsigned int, fd)
512{
513 struct fd f = fdget_raw(fd);
514 int error;
515
516 error = -EBADF;
517 if (!f.file)
518 goto out;
519
520 error = -ENOTDIR;
521 if (!d_can_lookup(f.file->f_path.dentry))
522 goto out_putf;
523
524 error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
525 if (!error)
526 set_fs_pwd(current->fs, &f.file->f_path);
527out_putf:
528 fdput(f);
529out:
530 return error;
531}
532
533SYSCALL_DEFINE1(chroot, const char __user *, filename)
534{
535 struct path path;
536 int error;
537 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
538retry:
539 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
540 if (error)
541 goto out;
542
543 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
544 if (error)
545 goto dput_and_out;
546
547 error = -EPERM;
548 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
549 goto dput_and_out;
550 error = security_path_chroot(&path);
551 if (error)
552 goto dput_and_out;
553
554 set_fs_root(current->fs, &path);
555 error = 0;
556dput_and_out:
557 path_put(&path);
558 if (retry_estale(error, lookup_flags)) {
559 lookup_flags |= LOOKUP_REVAL;
560 goto retry;
561 }
562out:
563 return error;
564}
565
566int chmod_common(const struct path *path, umode_t mode)
567{
568 struct inode *inode = path->dentry->d_inode;
569 struct inode *delegated_inode = NULL;
570 struct iattr newattrs;
571 int error;
572
573 error = mnt_want_write(path->mnt);
574 if (error)
575 return error;
576retry_deleg:
577 inode_lock(inode);
578 error = security_path_chmod(path, mode);
579 if (error)
580 goto out_unlock;
581 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
582 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
583 error = notify_change(path->dentry, &newattrs, &delegated_inode);
584out_unlock:
585 inode_unlock(inode);
586 if (delegated_inode) {
587 error = break_deleg_wait(&delegated_inode);
588 if (!error)
589 goto retry_deleg;
590 }
591 mnt_drop_write(path->mnt);
592 return error;
593}
594
595int vfs_fchmod(struct file *file, umode_t mode)
596{
597 audit_file(file);
598 return chmod_common(&file->f_path, mode);
599}
600
601SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
602{
603 struct fd f = fdget(fd);
604 int err = -EBADF;
605
606 if (f.file) {
607 err = vfs_fchmod(f.file, mode);
608 fdput(f);
609 }
610 return err;
611}
612
613static int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
614{
615 struct path path;
616 int error;
617 unsigned int lookup_flags = LOOKUP_FOLLOW;
618retry:
619 error = user_path_at(dfd, filename, lookup_flags, &path);
620 if (!error) {
621 error = chmod_common(&path, mode);
622 path_put(&path);
623 if (retry_estale(error, lookup_flags)) {
624 lookup_flags |= LOOKUP_REVAL;
625 goto retry;
626 }
627 }
628 return error;
629}
630
631SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
632 umode_t, mode)
633{
634 return do_fchmodat(dfd, filename, mode);
635}
636
637SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
638{
639 return do_fchmodat(AT_FDCWD, filename, mode);
640}
641
642int chown_common(const struct path *path, uid_t user, gid_t group)
643{
644 struct inode *inode = path->dentry->d_inode;
645 struct inode *delegated_inode = NULL;
646 int error;
647 struct iattr newattrs;
648 kuid_t uid;
649 kgid_t gid;
650
651 uid = make_kuid(current_user_ns(), user);
652 gid = make_kgid(current_user_ns(), group);
653
654retry_deleg:
655 newattrs.ia_valid = ATTR_CTIME;
656 if (user != (uid_t) -1) {
657 if (!uid_valid(uid))
658 return -EINVAL;
659 newattrs.ia_valid |= ATTR_UID;
660 newattrs.ia_uid = uid;
661 }
662 if (group != (gid_t) -1) {
663 if (!gid_valid(gid))
664 return -EINVAL;
665 newattrs.ia_valid |= ATTR_GID;
666 newattrs.ia_gid = gid;
667 }
668 if (!S_ISDIR(inode->i_mode))
669 newattrs.ia_valid |=
670 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
671 inode_lock(inode);
672 error = security_path_chown(path, uid, gid);
673 if (!error)
674 error = notify_change(path->dentry, &newattrs, &delegated_inode);
675 inode_unlock(inode);
676 if (delegated_inode) {
677 error = break_deleg_wait(&delegated_inode);
678 if (!error)
679 goto retry_deleg;
680 }
681 return error;
682}
683
684int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
685 int flag)
686{
687 struct path path;
688 int error = -EINVAL;
689 int lookup_flags;
690
691 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
692 goto out;
693
694 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
695 if (flag & AT_EMPTY_PATH)
696 lookup_flags |= LOOKUP_EMPTY;
697retry:
698 error = user_path_at(dfd, filename, lookup_flags, &path);
699 if (error)
700 goto out;
701 error = mnt_want_write(path.mnt);
702 if (error)
703 goto out_release;
704 error = chown_common(&path, user, group);
705 mnt_drop_write(path.mnt);
706out_release:
707 path_put(&path);
708 if (retry_estale(error, lookup_flags)) {
709 lookup_flags |= LOOKUP_REVAL;
710 goto retry;
711 }
712out:
713 return error;
714}
715
716SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
717 gid_t, group, int, flag)
718{
719 return do_fchownat(dfd, filename, user, group, flag);
720}
721
722SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
723{
724 return do_fchownat(AT_FDCWD, filename, user, group, 0);
725}
726
727SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
728{
729 return do_fchownat(AT_FDCWD, filename, user, group,
730 AT_SYMLINK_NOFOLLOW);
731}
732
733int vfs_fchown(struct file *file, uid_t user, gid_t group)
734{
735 int error;
736
737 error = mnt_want_write_file(file);
738 if (error)
739 return error;
740 audit_file(file);
741 error = chown_common(&file->f_path, user, group);
742 mnt_drop_write_file(file);
743 return error;
744}
745
746int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
747{
748 struct fd f = fdget(fd);
749 int error = -EBADF;
750
751 if (f.file) {
752 error = vfs_fchown(f.file, user, group);
753 fdput(f);
754 }
755 return error;
756}
757
758SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
759{
760 return ksys_fchown(fd, user, group);
761}
762
763static int do_dentry_open(struct file *f,
764 struct inode *inode,
765 int (*open)(struct inode *, struct file *))
766{
767 static const struct file_operations empty_fops = {};
768 int error;
769
770 path_get(&f->f_path);
771 f->f_inode = inode;
772 f->f_mapping = inode->i_mapping;
773 f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
774 f->f_sb_err = file_sample_sb_err(f);
775
776 if (unlikely(f->f_flags & O_PATH)) {
777 f->f_mode = FMODE_PATH | FMODE_OPENED;
778 f->f_op = &empty_fops;
779 return 0;
780 }
781
782 if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
783 error = get_write_access(inode);
784 if (unlikely(error))
785 goto cleanup_file;
786 error = __mnt_want_write(f->f_path.mnt);
787 if (unlikely(error)) {
788 put_write_access(inode);
789 goto cleanup_file;
790 }
791 f->f_mode |= FMODE_WRITER;
792 }
793
794 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
795 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
796 f->f_mode |= FMODE_ATOMIC_POS;
797
798 f->f_op = fops_get(inode->i_fop);
799 if (WARN_ON(!f->f_op)) {
800 error = -ENODEV;
801 goto cleanup_all;
802 }
803
804 error = security_file_open(f);
805 if (error)
806 goto cleanup_all;
807
808 error = break_lease(locks_inode(f), f->f_flags);
809 if (error)
810 goto cleanup_all;
811
812 /* normally all 3 are set; ->open() can clear them if needed */
813 f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
814 if (!open)
815 open = f->f_op->open;
816 if (open) {
817 error = open(inode, f);
818 if (error)
819 goto cleanup_all;
820 }
821 f->f_mode |= FMODE_OPENED;
822 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
823 i_readcount_inc(inode);
824 if ((f->f_mode & FMODE_READ) &&
825 likely(f->f_op->read || f->f_op->read_iter))
826 f->f_mode |= FMODE_CAN_READ;
827 if ((f->f_mode & FMODE_WRITE) &&
828 likely(f->f_op->write || f->f_op->write_iter))
829 f->f_mode |= FMODE_CAN_WRITE;
830
831 f->f_write_hint = WRITE_LIFE_NOT_SET;
832 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
833
834 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
835
836 /* NB: we're sure to have correct a_ops only after f_op->open */
837 if (f->f_flags & O_DIRECT) {
838 if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
839 return -EINVAL;
840 }
841
842 /*
843 * XXX: Huge page cache doesn't support writing yet. Drop all page
844 * cache for this file before processing writes.
845 */
846 if ((f->f_mode & FMODE_WRITE) && filemap_nr_thps(inode->i_mapping))
847 truncate_pagecache(inode, 0);
848
849 return 0;
850
851cleanup_all:
852 if (WARN_ON_ONCE(error > 0))
853 error = -EINVAL;
854 fops_put(f->f_op);
855 if (f->f_mode & FMODE_WRITER) {
856 put_write_access(inode);
857 __mnt_drop_write(f->f_path.mnt);
858 }
859cleanup_file:
860 path_put(&f->f_path);
861 f->f_path.mnt = NULL;
862 f->f_path.dentry = NULL;
863 f->f_inode = NULL;
864 return error;
865}
866
867/**
868 * finish_open - finish opening a file
869 * @file: file pointer
870 * @dentry: pointer to dentry
871 * @open: open callback
872 * @opened: state of open
873 *
874 * This can be used to finish opening a file passed to i_op->atomic_open().
875 *
876 * If the open callback is set to NULL, then the standard f_op->open()
877 * filesystem callback is substituted.
878 *
879 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
880 * the return value of d_splice_alias(), then the caller needs to perform dput()
881 * on it after finish_open().
882 *
883 * Returns zero on success or -errno if the open failed.
884 */
885int finish_open(struct file *file, struct dentry *dentry,
886 int (*open)(struct inode *, struct file *))
887{
888 BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
889
890 file->f_path.dentry = dentry;
891 return do_dentry_open(file, d_backing_inode(dentry), open);
892}
893EXPORT_SYMBOL(finish_open);
894
895/**
896 * finish_no_open - finish ->atomic_open() without opening the file
897 *
898 * @file: file pointer
899 * @dentry: dentry or NULL (as returned from ->lookup())
900 *
901 * This can be used to set the result of a successful lookup in ->atomic_open().
902 *
903 * NB: unlike finish_open() this function does consume the dentry reference and
904 * the caller need not dput() it.
905 *
906 * Returns "0" which must be the return value of ->atomic_open() after having
907 * called this function.
908 */
909int finish_no_open(struct file *file, struct dentry *dentry)
910{
911 file->f_path.dentry = dentry;
912 return 0;
913}
914EXPORT_SYMBOL(finish_no_open);
915
916char *file_path(struct file *filp, char *buf, int buflen)
917{
918 return d_path(&filp->f_path, buf, buflen);
919}
920EXPORT_SYMBOL(file_path);
921
922/**
923 * vfs_open - open the file at the given path
924 * @path: path to open
925 * @file: newly allocated file with f_flag initialized
926 * @cred: credentials to use
927 */
928int vfs_open(const struct path *path, struct file *file)
929{
930 file->f_path = *path;
931 return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
932}
933
934struct file *dentry_open(const struct path *path, int flags,
935 const struct cred *cred)
936{
937 int error;
938 struct file *f;
939
940 validate_creds(cred);
941
942 /* We must always pass in a valid mount pointer. */
943 BUG_ON(!path->mnt);
944
945 f = alloc_empty_file(flags, cred);
946 if (!IS_ERR(f)) {
947 error = vfs_open(path, f);
948 if (error) {
949 fput(f);
950 f = ERR_PTR(error);
951 }
952 }
953 return f;
954}
955EXPORT_SYMBOL(dentry_open);
956
957struct file *open_with_fake_path(const struct path *path, int flags,
958 struct inode *inode, const struct cred *cred)
959{
960 struct file *f = alloc_empty_file_noaccount(flags, cred);
961 if (!IS_ERR(f)) {
962 int error;
963
964 f->f_path = *path;
965 error = do_dentry_open(f, inode, NULL);
966 if (error) {
967 fput(f);
968 f = ERR_PTR(error);
969 }
970 }
971 return f;
972}
973EXPORT_SYMBOL(open_with_fake_path);
974
975#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE))
976#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
977
978inline struct open_how build_open_how(int flags, umode_t mode)
979{
980 struct open_how how = {
981 .flags = flags & VALID_OPEN_FLAGS,
982 .mode = mode & S_IALLUGO,
983 };
984
985 /* O_PATH beats everything else. */
986 if (how.flags & O_PATH)
987 how.flags &= O_PATH_FLAGS;
988 /* Modes should only be set for create-like flags. */
989 if (!WILL_CREATE(how.flags))
990 how.mode = 0;
991 return how;
992}
993
994inline int build_open_flags(const struct open_how *how, struct open_flags *op)
995{
996 int flags = how->flags;
997 int lookup_flags = 0;
998 int acc_mode = ACC_MODE(flags);
999
1000 /* Must never be set by userspace */
1001 flags &= ~(FMODE_NONOTIFY | O_CLOEXEC);
1002
1003 /*
1004 * Older syscalls implicitly clear all of the invalid flags or argument
1005 * values before calling build_open_flags(), but openat2(2) checks all
1006 * of its arguments.
1007 */
1008 if (flags & ~VALID_OPEN_FLAGS)
1009 return -EINVAL;
1010 if (how->resolve & ~VALID_RESOLVE_FLAGS)
1011 return -EINVAL;
1012
1013 /* Deal with the mode. */
1014 if (WILL_CREATE(flags)) {
1015 if (how->mode & ~S_IALLUGO)
1016 return -EINVAL;
1017 op->mode = how->mode | S_IFREG;
1018 } else {
1019 if (how->mode != 0)
1020 return -EINVAL;
1021 op->mode = 0;
1022 }
1023
1024 /*
1025 * In order to ensure programs get explicit errors when trying to use
1026 * O_TMPFILE on old kernels, O_TMPFILE is implemented such that it
1027 * looks like (O_DIRECTORY|O_RDWR & ~O_CREAT) to old kernels. But we
1028 * have to require userspace to explicitly set it.
1029 */
1030 if (flags & __O_TMPFILE) {
1031 if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
1032 return -EINVAL;
1033 if (!(acc_mode & MAY_WRITE))
1034 return -EINVAL;
1035 }
1036 if (flags & O_PATH) {
1037 /* O_PATH only permits certain other flags to be set. */
1038 if (flags & ~O_PATH_FLAGS)
1039 return -EINVAL;
1040 acc_mode = 0;
1041 }
1042
1043 /*
1044 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1045 * check for O_DSYNC if the need any syncing at all we enforce it's
1046 * always set instead of having to deal with possibly weird behaviour
1047 * for malicious applications setting only __O_SYNC.
1048 */
1049 if (flags & __O_SYNC)
1050 flags |= O_DSYNC;
1051
1052 op->open_flag = flags;
1053
1054 /* O_TRUNC implies we need access checks for write permissions */
1055 if (flags & O_TRUNC)
1056 acc_mode |= MAY_WRITE;
1057
1058 /* Allow the LSM permission hook to distinguish append
1059 access from general write access. */
1060 if (flags & O_APPEND)
1061 acc_mode |= MAY_APPEND;
1062
1063 op->acc_mode = acc_mode;
1064
1065 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1066
1067 if (flags & O_CREAT) {
1068 op->intent |= LOOKUP_CREATE;
1069 if (flags & O_EXCL) {
1070 op->intent |= LOOKUP_EXCL;
1071 flags |= O_NOFOLLOW;
1072 }
1073 }
1074
1075 if (flags & O_DIRECTORY)
1076 lookup_flags |= LOOKUP_DIRECTORY;
1077 if (!(flags & O_NOFOLLOW))
1078 lookup_flags |= LOOKUP_FOLLOW;
1079
1080 if (how->resolve & RESOLVE_NO_XDEV)
1081 lookup_flags |= LOOKUP_NO_XDEV;
1082 if (how->resolve & RESOLVE_NO_MAGICLINKS)
1083 lookup_flags |= LOOKUP_NO_MAGICLINKS;
1084 if (how->resolve & RESOLVE_NO_SYMLINKS)
1085 lookup_flags |= LOOKUP_NO_SYMLINKS;
1086 if (how->resolve & RESOLVE_BENEATH)
1087 lookup_flags |= LOOKUP_BENEATH;
1088 if (how->resolve & RESOLVE_IN_ROOT)
1089 lookup_flags |= LOOKUP_IN_ROOT;
1090
1091 op->lookup_flags = lookup_flags;
1092 return 0;
1093}
1094
1095/**
1096 * file_open_name - open file and return file pointer
1097 *
1098 * @name: struct filename containing path to open
1099 * @flags: open flags as per the open(2) second argument
1100 * @mode: mode for the new file if O_CREAT is set, else ignored
1101 *
1102 * This is the helper to open a file from kernelspace if you really
1103 * have to. But in generally you should not do this, so please move
1104 * along, nothing to see here..
1105 */
1106struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1107{
1108 struct open_flags op;
1109 struct open_how how = build_open_how(flags, mode);
1110 int err = build_open_flags(&how, &op);
1111 if (err)
1112 return ERR_PTR(err);
1113 return do_filp_open(AT_FDCWD, name, &op);
1114}
1115
1116/**
1117 * filp_open - open file and return file pointer
1118 *
1119 * @filename: path to open
1120 * @flags: open flags as per the open(2) second argument
1121 * @mode: mode for the new file if O_CREAT is set, else ignored
1122 *
1123 * This is the helper to open a file from kernelspace if you really
1124 * have to. But in generally you should not do this, so please move
1125 * along, nothing to see here..
1126 */
1127struct file *filp_open(const char *filename, int flags, umode_t mode)
1128{
1129 struct filename *name = getname_kernel(filename);
1130 struct file *file = ERR_CAST(name);
1131
1132 if (!IS_ERR(name)) {
1133 file = file_open_name(name, flags, mode);
1134 putname(name);
1135 }
1136 return file;
1137}
1138EXPORT_SYMBOL(filp_open);
1139
1140struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
1141 const char *filename, int flags, umode_t mode)
1142{
1143 struct open_flags op;
1144 struct open_how how = build_open_how(flags, mode);
1145 int err = build_open_flags(&how, &op);
1146 if (err)
1147 return ERR_PTR(err);
1148 return do_file_open_root(dentry, mnt, filename, &op);
1149}
1150EXPORT_SYMBOL(file_open_root);
1151
1152static long do_sys_openat2(int dfd, const char __user *filename,
1153 struct open_how *how)
1154{
1155 struct open_flags op;
1156 int fd = build_open_flags(how, &op);
1157 struct filename *tmp;
1158
1159 if (fd)
1160 return fd;
1161
1162 tmp = getname(filename);
1163 if (IS_ERR(tmp))
1164 return PTR_ERR(tmp);
1165
1166 fd = get_unused_fd_flags(how->flags);
1167 if (fd >= 0) {
1168 struct file *f = do_filp_open(dfd, tmp, &op);
1169 if (IS_ERR(f)) {
1170 put_unused_fd(fd);
1171 fd = PTR_ERR(f);
1172 } else {
1173 fsnotify_open(f);
1174 fd_install(fd, f);
1175 }
1176 }
1177 putname(tmp);
1178 return fd;
1179}
1180
1181long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1182{
1183 struct open_how how = build_open_how(flags, mode);
1184 return do_sys_openat2(dfd, filename, &how);
1185}
1186
1187
1188SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1189{
1190 if (force_o_largefile())
1191 flags |= O_LARGEFILE;
1192 return do_sys_open(AT_FDCWD, filename, flags, mode);
1193}
1194
1195SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1196 umode_t, mode)
1197{
1198 if (force_o_largefile())
1199 flags |= O_LARGEFILE;
1200 return do_sys_open(dfd, filename, flags, mode);
1201}
1202
1203SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1204 struct open_how __user *, how, size_t, usize)
1205{
1206 int err;
1207 struct open_how tmp;
1208
1209 BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1210 BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1211
1212 if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1213 return -EINVAL;
1214
1215 err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
1216 if (err)
1217 return err;
1218
1219 /* O_LARGEFILE is only allowed for non-O_PATH. */
1220 if (!(tmp.flags & O_PATH) && force_o_largefile())
1221 tmp.flags |= O_LARGEFILE;
1222
1223 return do_sys_openat2(dfd, filename, &tmp);
1224}
1225
1226#ifdef CONFIG_COMPAT
1227/*
1228 * Exactly like sys_open(), except that it doesn't set the
1229 * O_LARGEFILE flag.
1230 */
1231COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1232{
1233 return do_sys_open(AT_FDCWD, filename, flags, mode);
1234}
1235
1236/*
1237 * Exactly like sys_openat(), except that it doesn't set the
1238 * O_LARGEFILE flag.
1239 */
1240COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1241{
1242 return do_sys_open(dfd, filename, flags, mode);
1243}
1244#endif
1245
1246#ifndef __alpha__
1247
1248/*
1249 * For backward compatibility? Maybe this should be moved
1250 * into arch/i386 instead?
1251 */
1252SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1253{
1254 int flags = O_CREAT | O_WRONLY | O_TRUNC;
1255
1256 if (force_o_largefile())
1257 flags |= O_LARGEFILE;
1258 return do_sys_open(AT_FDCWD, pathname, flags, mode);
1259}
1260#endif
1261
1262/*
1263 * "id" is the POSIX thread ID. We use the
1264 * files pointer for this..
1265 */
1266int filp_close(struct file *filp, fl_owner_t id)
1267{
1268 int retval = 0;
1269
1270 if (!file_count(filp)) {
1271 printk(KERN_ERR "VFS: Close: file count is 0\n");
1272 return 0;
1273 }
1274
1275 if (filp->f_op->flush)
1276 retval = filp->f_op->flush(filp, id);
1277
1278 if (likely(!(filp->f_mode & FMODE_PATH))) {
1279 dnotify_flush(filp, id);
1280 locks_remove_posix(filp, id);
1281 }
1282 fput(filp);
1283 return retval;
1284}
1285
1286EXPORT_SYMBOL(filp_close);
1287
1288/*
1289 * Careful here! We test whether the file pointer is NULL before
1290 * releasing the fd. This ensures that one clone task can't release
1291 * an fd while another clone is opening it.
1292 */
1293SYSCALL_DEFINE1(close, unsigned int, fd)
1294{
1295 int retval = __close_fd(current->files, fd);
1296
1297 /* can't restart close syscall because file table entry was cleared */
1298 if (unlikely(retval == -ERESTARTSYS ||
1299 retval == -ERESTARTNOINTR ||
1300 retval == -ERESTARTNOHAND ||
1301 retval == -ERESTART_RESTARTBLOCK))
1302 retval = -EINTR;
1303
1304 return retval;
1305}
1306
1307/**
1308 * close_range() - Close all file descriptors in a given range.
1309 *
1310 * @fd: starting file descriptor to close
1311 * @max_fd: last file descriptor to close
1312 * @flags: reserved for future extensions
1313 *
1314 * This closes a range of file descriptors. All file descriptors
1315 * from @fd up to and including @max_fd are closed.
1316 * Currently, errors to close a given file descriptor are ignored.
1317 */
1318SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
1319 unsigned int, flags)
1320{
1321 return __close_range(fd, max_fd, flags);
1322}
1323
1324/*
1325 * This routine simulates a hangup on the tty, to arrange that users
1326 * are given clean terminals at login time.
1327 */
1328SYSCALL_DEFINE0(vhangup)
1329{
1330 if (capable(CAP_SYS_TTY_CONFIG)) {
1331 tty_vhangup_self();
1332 return 0;
1333 }
1334 return -EPERM;
1335}
1336
1337/*
1338 * Called when an inode is about to be open.
1339 * We use this to disallow opening large files on 32bit systems if
1340 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1341 * on this flag in sys_open.
1342 */
1343int generic_file_open(struct inode * inode, struct file * filp)
1344{
1345 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1346 return -EOVERFLOW;
1347 return 0;
1348}
1349
1350EXPORT_SYMBOL(generic_file_open);
1351
1352/*
1353 * This is used by subsystems that don't want seekable
1354 * file descriptors. The function is not supposed to ever fail, the only
1355 * reason it returns an 'int' and not 'void' is so that it can be plugged
1356 * directly into file_operations structure.
1357 */
1358int nonseekable_open(struct inode *inode, struct file *filp)
1359{
1360 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1361 return 0;
1362}
1363
1364EXPORT_SYMBOL(nonseekable_open);
1365
1366/*
1367 * stream_open is used by subsystems that want stream-like file descriptors.
1368 * Such file descriptors are not seekable and don't have notion of position
1369 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1370 * Contrary to file descriptors of other regular files, .read() and .write()
1371 * can run simultaneously.
1372 *
1373 * stream_open never fails and is marked to return int so that it could be
1374 * directly used as file_operations.open .
1375 */
1376int stream_open(struct inode *inode, struct file *filp)
1377{
1378 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1379 filp->f_mode |= FMODE_STREAM;
1380 return 0;
1381}
1382
1383EXPORT_SYMBOL(stream_open);
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);