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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 <linux/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(const struct path *path, loff_t length)
69{
70 struct inode *inode;
71 struct dentry *upperdentry;
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 /*
95 * If this is an overlayfs then do as if opening the file so we get
96 * write access on the upper inode, not on the overlay inode. For
97 * non-overlay filesystems d_real() is an identity function.
98 */
99 upperdentry = d_real(path->dentry, NULL, O_WRONLY);
100 error = PTR_ERR(upperdentry);
101 if (IS_ERR(upperdentry))
102 goto mnt_drop_write_and_out;
103
104 error = get_write_access(upperdentry->d_inode);
105 if (error)
106 goto mnt_drop_write_and_out;
107
108 /*
109 * Make sure that there are no leases. get_write_access() protects
110 * against the truncate racing with a lease-granting setlease().
111 */
112 error = break_lease(inode, O_WRONLY);
113 if (error)
114 goto put_write_and_out;
115
116 error = locks_verify_truncate(inode, NULL, length);
117 if (!error)
118 error = security_path_truncate(path);
119 if (!error)
120 error = do_truncate(path->dentry, length, 0, NULL);
121
122put_write_and_out:
123 put_write_access(upperdentry->d_inode);
124mnt_drop_write_and_out:
125 mnt_drop_write(path->mnt);
126out:
127 return error;
128}
129EXPORT_SYMBOL_GPL(vfs_truncate);
130
131static long do_sys_truncate(const char __user *pathname, loff_t length)
132{
133 unsigned int lookup_flags = LOOKUP_FOLLOW;
134 struct path path;
135 int error;
136
137 if (length < 0) /* sorry, but loff_t says... */
138 return -EINVAL;
139
140retry:
141 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
142 if (!error) {
143 error = vfs_truncate(&path, length);
144 path_put(&path);
145 }
146 if (retry_estale(error, lookup_flags)) {
147 lookup_flags |= LOOKUP_REVAL;
148 goto retry;
149 }
150 return error;
151}
152
153SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
154{
155 return do_sys_truncate(path, length);
156}
157
158#ifdef CONFIG_COMPAT
159COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
160{
161 return do_sys_truncate(path, length);
162}
163#endif
164
165static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
166{
167 struct inode *inode;
168 struct dentry *dentry;
169 struct fd f;
170 int error;
171
172 error = -EINVAL;
173 if (length < 0)
174 goto out;
175 error = -EBADF;
176 f = fdget(fd);
177 if (!f.file)
178 goto out;
179
180 /* explicitly opened as large or we are on 64-bit box */
181 if (f.file->f_flags & O_LARGEFILE)
182 small = 0;
183
184 dentry = f.file->f_path.dentry;
185 inode = dentry->d_inode;
186 error = -EINVAL;
187 if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
188 goto out_putf;
189
190 error = -EINVAL;
191 /* Cannot ftruncate over 2^31 bytes without large file support */
192 if (small && length > MAX_NON_LFS)
193 goto out_putf;
194
195 error = -EPERM;
196 if (IS_APPEND(inode))
197 goto out_putf;
198
199 sb_start_write(inode->i_sb);
200 error = locks_verify_truncate(inode, f.file, length);
201 if (!error)
202 error = security_path_truncate(&f.file->f_path);
203 if (!error)
204 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
205 sb_end_write(inode->i_sb);
206out_putf:
207 fdput(f);
208out:
209 return error;
210}
211
212SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
213{
214 return do_sys_ftruncate(fd, length, 1);
215}
216
217#ifdef CONFIG_COMPAT
218COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
219{
220 return do_sys_ftruncate(fd, length, 1);
221}
222#endif
223
224/* LFS versions of truncate are only needed on 32 bit machines */
225#if BITS_PER_LONG == 32
226SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
227{
228 return do_sys_truncate(path, length);
229}
230
231SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
232{
233 return do_sys_ftruncate(fd, length, 0);
234}
235#endif /* BITS_PER_LONG == 32 */
236
237
238int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
239{
240 struct inode *inode = file_inode(file);
241 long ret;
242
243 if (offset < 0 || len <= 0)
244 return -EINVAL;
245
246 /* Return error if mode is not supported */
247 if (mode & ~FALLOC_FL_SUPPORTED_MASK)
248 return -EOPNOTSUPP;
249
250 /* Punch hole and zero range are mutually exclusive */
251 if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
252 (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
253 return -EOPNOTSUPP;
254
255 /* Punch hole must have keep size set */
256 if ((mode & FALLOC_FL_PUNCH_HOLE) &&
257 !(mode & FALLOC_FL_KEEP_SIZE))
258 return -EOPNOTSUPP;
259
260 /* Collapse range should only be used exclusively. */
261 if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
262 (mode & ~FALLOC_FL_COLLAPSE_RANGE))
263 return -EINVAL;
264
265 /* Insert range should only be used exclusively. */
266 if ((mode & FALLOC_FL_INSERT_RANGE) &&
267 (mode & ~FALLOC_FL_INSERT_RANGE))
268 return -EINVAL;
269
270 /* Unshare range should only be used with allocate mode. */
271 if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
272 (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
273 return -EINVAL;
274
275 if (!(file->f_mode & FMODE_WRITE))
276 return -EBADF;
277
278 /*
279 * We can only allow pure fallocate on append only files
280 */
281 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
282 return -EPERM;
283
284 if (IS_IMMUTABLE(inode))
285 return -EPERM;
286
287 /*
288 * We cannot allow any fallocate operation on an active swapfile
289 */
290 if (IS_SWAPFILE(inode))
291 return -ETXTBSY;
292
293 /*
294 * Revalidate the write permissions, in case security policy has
295 * changed since the files were opened.
296 */
297 ret = security_file_permission(file, MAY_WRITE);
298 if (ret)
299 return ret;
300
301 if (S_ISFIFO(inode->i_mode))
302 return -ESPIPE;
303
304 /*
305 * Let individual file system decide if it supports preallocation
306 * for directories or not.
307 */
308 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode) &&
309 !S_ISBLK(inode->i_mode))
310 return -ENODEV;
311
312 /* Check for wrap through zero too */
313 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
314 return -EFBIG;
315
316 if (!file->f_op->fallocate)
317 return -EOPNOTSUPP;
318
319 sb_start_write(inode->i_sb);
320 ret = file->f_op->fallocate(file, mode, offset, len);
321
322 /*
323 * Create inotify and fanotify events.
324 *
325 * To keep the logic simple always create events if fallocate succeeds.
326 * This implies that events are even created if the file size remains
327 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
328 */
329 if (ret == 0)
330 fsnotify_modify(file);
331
332 sb_end_write(inode->i_sb);
333 return ret;
334}
335EXPORT_SYMBOL_GPL(vfs_fallocate);
336
337SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
338{
339 struct fd f = fdget(fd);
340 int error = -EBADF;
341
342 if (f.file) {
343 error = vfs_fallocate(f.file, mode, offset, len);
344 fdput(f);
345 }
346 return error;
347}
348
349/*
350 * access() needs to use the real uid/gid, not the effective uid/gid.
351 * We do this by temporarily clearing all FS-related capabilities and
352 * switching the fsuid/fsgid around to the real ones.
353 */
354SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
355{
356 const struct cred *old_cred;
357 struct cred *override_cred;
358 struct path path;
359 struct inode *inode;
360 int res;
361 unsigned int lookup_flags = LOOKUP_FOLLOW;
362
363 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
364 return -EINVAL;
365
366 override_cred = prepare_creds();
367 if (!override_cred)
368 return -ENOMEM;
369
370 override_cred->fsuid = override_cred->uid;
371 override_cred->fsgid = override_cred->gid;
372
373 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
374 /* Clear the capabilities if we switch to a non-root user */
375 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
376 if (!uid_eq(override_cred->uid, root_uid))
377 cap_clear(override_cred->cap_effective);
378 else
379 override_cred->cap_effective =
380 override_cred->cap_permitted;
381 }
382
383 old_cred = override_creds(override_cred);
384retry:
385 res = user_path_at(dfd, filename, lookup_flags, &path);
386 if (res)
387 goto out;
388
389 inode = d_backing_inode(path.dentry);
390
391 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
392 /*
393 * MAY_EXEC on regular files is denied if the fs is mounted
394 * with the "noexec" flag.
395 */
396 res = -EACCES;
397 if (path_noexec(&path))
398 goto out_path_release;
399 }
400
401 res = inode_permission(inode, mode | MAY_ACCESS);
402 /* SuS v2 requires we report a read only fs too */
403 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
404 goto out_path_release;
405 /*
406 * This is a rare case where using __mnt_is_readonly()
407 * is OK without a mnt_want/drop_write() pair. Since
408 * no actual write to the fs is performed here, we do
409 * not need to telegraph to that to anyone.
410 *
411 * By doing this, we accept that this access is
412 * inherently racy and know that the fs may change
413 * state before we even see this result.
414 */
415 if (__mnt_is_readonly(path.mnt))
416 res = -EROFS;
417
418out_path_release:
419 path_put(&path);
420 if (retry_estale(res, lookup_flags)) {
421 lookup_flags |= LOOKUP_REVAL;
422 goto retry;
423 }
424out:
425 revert_creds(old_cred);
426 put_cred(override_cred);
427 return res;
428}
429
430SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
431{
432 return sys_faccessat(AT_FDCWD, filename, mode);
433}
434
435SYSCALL_DEFINE1(chdir, const char __user *, filename)
436{
437 struct path path;
438 int error;
439 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
440retry:
441 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
442 if (error)
443 goto out;
444
445 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
446 if (error)
447 goto dput_and_out;
448
449 set_fs_pwd(current->fs, &path);
450
451dput_and_out:
452 path_put(&path);
453 if (retry_estale(error, lookup_flags)) {
454 lookup_flags |= LOOKUP_REVAL;
455 goto retry;
456 }
457out:
458 return error;
459}
460
461SYSCALL_DEFINE1(fchdir, unsigned int, fd)
462{
463 struct fd f = fdget_raw(fd);
464 struct inode *inode;
465 int error = -EBADF;
466
467 error = -EBADF;
468 if (!f.file)
469 goto out;
470
471 inode = file_inode(f.file);
472
473 error = -ENOTDIR;
474 if (!S_ISDIR(inode->i_mode))
475 goto out_putf;
476
477 error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
478 if (!error)
479 set_fs_pwd(current->fs, &f.file->f_path);
480out_putf:
481 fdput(f);
482out:
483 return error;
484}
485
486SYSCALL_DEFINE1(chroot, const char __user *, filename)
487{
488 struct path path;
489 int error;
490 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
491retry:
492 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
493 if (error)
494 goto out;
495
496 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
497 if (error)
498 goto dput_and_out;
499
500 error = -EPERM;
501 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
502 goto dput_and_out;
503 error = security_path_chroot(&path);
504 if (error)
505 goto dput_and_out;
506
507 set_fs_root(current->fs, &path);
508 error = 0;
509dput_and_out:
510 path_put(&path);
511 if (retry_estale(error, lookup_flags)) {
512 lookup_flags |= LOOKUP_REVAL;
513 goto retry;
514 }
515out:
516 return error;
517}
518
519static int chmod_common(const struct path *path, umode_t mode)
520{
521 struct inode *inode = path->dentry->d_inode;
522 struct inode *delegated_inode = NULL;
523 struct iattr newattrs;
524 int error;
525
526 error = mnt_want_write(path->mnt);
527 if (error)
528 return error;
529retry_deleg:
530 inode_lock(inode);
531 error = security_path_chmod(path, mode);
532 if (error)
533 goto out_unlock;
534 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
535 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
536 error = notify_change(path->dentry, &newattrs, &delegated_inode);
537out_unlock:
538 inode_unlock(inode);
539 if (delegated_inode) {
540 error = break_deleg_wait(&delegated_inode);
541 if (!error)
542 goto retry_deleg;
543 }
544 mnt_drop_write(path->mnt);
545 return error;
546}
547
548SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
549{
550 struct fd f = fdget(fd);
551 int err = -EBADF;
552
553 if (f.file) {
554 audit_file(f.file);
555 err = chmod_common(&f.file->f_path, mode);
556 fdput(f);
557 }
558 return err;
559}
560
561SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode)
562{
563 struct path path;
564 int error;
565 unsigned int lookup_flags = LOOKUP_FOLLOW;
566retry:
567 error = user_path_at(dfd, filename, lookup_flags, &path);
568 if (!error) {
569 error = chmod_common(&path, mode);
570 path_put(&path);
571 if (retry_estale(error, lookup_flags)) {
572 lookup_flags |= LOOKUP_REVAL;
573 goto retry;
574 }
575 }
576 return error;
577}
578
579SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
580{
581 return sys_fchmodat(AT_FDCWD, filename, mode);
582}
583
584static int chown_common(const struct path *path, uid_t user, gid_t group)
585{
586 struct inode *inode = path->dentry->d_inode;
587 struct inode *delegated_inode = NULL;
588 int error;
589 struct iattr newattrs;
590 kuid_t uid;
591 kgid_t gid;
592
593 uid = make_kuid(current_user_ns(), user);
594 gid = make_kgid(current_user_ns(), group);
595
596retry_deleg:
597 newattrs.ia_valid = ATTR_CTIME;
598 if (user != (uid_t) -1) {
599 if (!uid_valid(uid))
600 return -EINVAL;
601 newattrs.ia_valid |= ATTR_UID;
602 newattrs.ia_uid = uid;
603 }
604 if (group != (gid_t) -1) {
605 if (!gid_valid(gid))
606 return -EINVAL;
607 newattrs.ia_valid |= ATTR_GID;
608 newattrs.ia_gid = gid;
609 }
610 if (!S_ISDIR(inode->i_mode))
611 newattrs.ia_valid |=
612 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
613 inode_lock(inode);
614 error = security_path_chown(path, uid, gid);
615 if (!error)
616 error = notify_change(path->dentry, &newattrs, &delegated_inode);
617 inode_unlock(inode);
618 if (delegated_inode) {
619 error = break_deleg_wait(&delegated_inode);
620 if (!error)
621 goto retry_deleg;
622 }
623 return error;
624}
625
626SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
627 gid_t, group, int, flag)
628{
629 struct path path;
630 int error = -EINVAL;
631 int lookup_flags;
632
633 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
634 goto out;
635
636 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
637 if (flag & AT_EMPTY_PATH)
638 lookup_flags |= LOOKUP_EMPTY;
639retry:
640 error = user_path_at(dfd, filename, lookup_flags, &path);
641 if (error)
642 goto out;
643 error = mnt_want_write(path.mnt);
644 if (error)
645 goto out_release;
646 error = chown_common(&path, user, group);
647 mnt_drop_write(path.mnt);
648out_release:
649 path_put(&path);
650 if (retry_estale(error, lookup_flags)) {
651 lookup_flags |= LOOKUP_REVAL;
652 goto retry;
653 }
654out:
655 return error;
656}
657
658SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
659{
660 return sys_fchownat(AT_FDCWD, filename, user, group, 0);
661}
662
663SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
664{
665 return sys_fchownat(AT_FDCWD, filename, user, group,
666 AT_SYMLINK_NOFOLLOW);
667}
668
669SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
670{
671 struct fd f = fdget(fd);
672 int error = -EBADF;
673
674 if (!f.file)
675 goto out;
676
677 error = mnt_want_write_file(f.file);
678 if (error)
679 goto out_fput;
680 audit_file(f.file);
681 error = chown_common(&f.file->f_path, user, group);
682 mnt_drop_write_file(f.file);
683out_fput:
684 fdput(f);
685out:
686 return error;
687}
688
689int open_check_o_direct(struct file *f)
690{
691 /* NB: we're sure to have correct a_ops only after f_op->open */
692 if (f->f_flags & O_DIRECT) {
693 if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
694 return -EINVAL;
695 }
696 return 0;
697}
698
699static int do_dentry_open(struct file *f,
700 struct inode *inode,
701 int (*open)(struct inode *, struct file *),
702 const struct cred *cred)
703{
704 static const struct file_operations empty_fops = {};
705 int error;
706
707 f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
708 FMODE_PREAD | FMODE_PWRITE;
709
710 path_get(&f->f_path);
711 f->f_inode = inode;
712 f->f_mapping = inode->i_mapping;
713
714 if (unlikely(f->f_flags & O_PATH)) {
715 f->f_mode = FMODE_PATH;
716 f->f_op = &empty_fops;
717 return 0;
718 }
719
720 if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
721 error = get_write_access(inode);
722 if (unlikely(error))
723 goto cleanup_file;
724 error = __mnt_want_write(f->f_path.mnt);
725 if (unlikely(error)) {
726 put_write_access(inode);
727 goto cleanup_file;
728 }
729 f->f_mode |= FMODE_WRITER;
730 }
731
732 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
733 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
734 f->f_mode |= FMODE_ATOMIC_POS;
735
736 f->f_op = fops_get(inode->i_fop);
737 if (unlikely(WARN_ON(!f->f_op))) {
738 error = -ENODEV;
739 goto cleanup_all;
740 }
741
742 error = security_file_open(f, cred);
743 if (error)
744 goto cleanup_all;
745
746 error = break_lease(locks_inode(f), f->f_flags);
747 if (error)
748 goto cleanup_all;
749
750 if (!open)
751 open = f->f_op->open;
752 if (open) {
753 error = open(inode, f);
754 if (error)
755 goto cleanup_all;
756 }
757 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
758 i_readcount_inc(inode);
759 if ((f->f_mode & FMODE_READ) &&
760 likely(f->f_op->read || f->f_op->read_iter))
761 f->f_mode |= FMODE_CAN_READ;
762 if ((f->f_mode & FMODE_WRITE) &&
763 likely(f->f_op->write || f->f_op->write_iter))
764 f->f_mode |= FMODE_CAN_WRITE;
765
766 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
767
768 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
769
770 return 0;
771
772cleanup_all:
773 fops_put(f->f_op);
774 if (f->f_mode & FMODE_WRITER) {
775 put_write_access(inode);
776 __mnt_drop_write(f->f_path.mnt);
777 }
778cleanup_file:
779 path_put(&f->f_path);
780 f->f_path.mnt = NULL;
781 f->f_path.dentry = NULL;
782 f->f_inode = NULL;
783 return error;
784}
785
786/**
787 * finish_open - finish opening a file
788 * @file: file pointer
789 * @dentry: pointer to dentry
790 * @open: open callback
791 * @opened: state of open
792 *
793 * This can be used to finish opening a file passed to i_op->atomic_open().
794 *
795 * If the open callback is set to NULL, then the standard f_op->open()
796 * filesystem callback is substituted.
797 *
798 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
799 * the return value of d_splice_alias(), then the caller needs to perform dput()
800 * on it after finish_open().
801 *
802 * On successful return @file is a fully instantiated open file. After this, if
803 * an error occurs in ->atomic_open(), it needs to clean up with fput().
804 *
805 * Returns zero on success or -errno if the open failed.
806 */
807int finish_open(struct file *file, struct dentry *dentry,
808 int (*open)(struct inode *, struct file *),
809 int *opened)
810{
811 int error;
812 BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
813
814 file->f_path.dentry = dentry;
815 error = do_dentry_open(file, d_backing_inode(dentry), open,
816 current_cred());
817 if (!error)
818 *opened |= FILE_OPENED;
819
820 return error;
821}
822EXPORT_SYMBOL(finish_open);
823
824/**
825 * finish_no_open - finish ->atomic_open() without opening the file
826 *
827 * @file: file pointer
828 * @dentry: dentry or NULL (as returned from ->lookup())
829 *
830 * This can be used to set the result of a successful lookup in ->atomic_open().
831 *
832 * NB: unlike finish_open() this function does consume the dentry reference and
833 * the caller need not dput() it.
834 *
835 * Returns "1" which must be the return value of ->atomic_open() after having
836 * called this function.
837 */
838int finish_no_open(struct file *file, struct dentry *dentry)
839{
840 file->f_path.dentry = dentry;
841 return 1;
842}
843EXPORT_SYMBOL(finish_no_open);
844
845char *file_path(struct file *filp, char *buf, int buflen)
846{
847 return d_path(&filp->f_path, buf, buflen);
848}
849EXPORT_SYMBOL(file_path);
850
851/**
852 * vfs_open - open the file at the given path
853 * @path: path to open
854 * @file: newly allocated file with f_flag initialized
855 * @cred: credentials to use
856 */
857int vfs_open(const struct path *path, struct file *file,
858 const struct cred *cred)
859{
860 struct dentry *dentry = d_real(path->dentry, NULL, file->f_flags);
861
862 if (IS_ERR(dentry))
863 return PTR_ERR(dentry);
864
865 file->f_path = *path;
866 return do_dentry_open(file, d_backing_inode(dentry), NULL, cred);
867}
868
869struct file *dentry_open(const struct path *path, int flags,
870 const struct cred *cred)
871{
872 int error;
873 struct file *f;
874
875 validate_creds(cred);
876
877 /* We must always pass in a valid mount pointer. */
878 BUG_ON(!path->mnt);
879
880 f = get_empty_filp();
881 if (!IS_ERR(f)) {
882 f->f_flags = flags;
883 error = vfs_open(path, f, cred);
884 if (!error) {
885 /* from now on we need fput() to dispose of f */
886 error = open_check_o_direct(f);
887 if (error) {
888 fput(f);
889 f = ERR_PTR(error);
890 }
891 } else {
892 put_filp(f);
893 f = ERR_PTR(error);
894 }
895 }
896 return f;
897}
898EXPORT_SYMBOL(dentry_open);
899
900static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
901{
902 int lookup_flags = 0;
903 int acc_mode = ACC_MODE(flags);
904
905 if (flags & (O_CREAT | __O_TMPFILE))
906 op->mode = (mode & S_IALLUGO) | S_IFREG;
907 else
908 op->mode = 0;
909
910 /* Must never be set by userspace */
911 flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC;
912
913 /*
914 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
915 * check for O_DSYNC if the need any syncing at all we enforce it's
916 * always set instead of having to deal with possibly weird behaviour
917 * for malicious applications setting only __O_SYNC.
918 */
919 if (flags & __O_SYNC)
920 flags |= O_DSYNC;
921
922 if (flags & __O_TMPFILE) {
923 if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
924 return -EINVAL;
925 if (!(acc_mode & MAY_WRITE))
926 return -EINVAL;
927 } else if (flags & O_PATH) {
928 /*
929 * If we have O_PATH in the open flag. Then we
930 * cannot have anything other than the below set of flags
931 */
932 flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
933 acc_mode = 0;
934 }
935
936 op->open_flag = flags;
937
938 /* O_TRUNC implies we need access checks for write permissions */
939 if (flags & O_TRUNC)
940 acc_mode |= MAY_WRITE;
941
942 /* Allow the LSM permission hook to distinguish append
943 access from general write access. */
944 if (flags & O_APPEND)
945 acc_mode |= MAY_APPEND;
946
947 op->acc_mode = acc_mode;
948
949 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
950
951 if (flags & O_CREAT) {
952 op->intent |= LOOKUP_CREATE;
953 if (flags & O_EXCL)
954 op->intent |= LOOKUP_EXCL;
955 }
956
957 if (flags & O_DIRECTORY)
958 lookup_flags |= LOOKUP_DIRECTORY;
959 if (!(flags & O_NOFOLLOW))
960 lookup_flags |= LOOKUP_FOLLOW;
961 op->lookup_flags = lookup_flags;
962 return 0;
963}
964
965/**
966 * file_open_name - open file and return file pointer
967 *
968 * @name: struct filename containing path to open
969 * @flags: open flags as per the open(2) second argument
970 * @mode: mode for the new file if O_CREAT is set, else ignored
971 *
972 * This is the helper to open a file from kernelspace if you really
973 * have to. But in generally you should not do this, so please move
974 * along, nothing to see here..
975 */
976struct file *file_open_name(struct filename *name, int flags, umode_t mode)
977{
978 struct open_flags op;
979 int err = build_open_flags(flags, mode, &op);
980 return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &op);
981}
982
983/**
984 * filp_open - open file and return file pointer
985 *
986 * @filename: path to open
987 * @flags: open flags as per the open(2) second argument
988 * @mode: mode for the new file if O_CREAT is set, else ignored
989 *
990 * This is the helper to open a file from kernelspace if you really
991 * have to. But in generally you should not do this, so please move
992 * along, nothing to see here..
993 */
994struct file *filp_open(const char *filename, int flags, umode_t mode)
995{
996 struct filename *name = getname_kernel(filename);
997 struct file *file = ERR_CAST(name);
998
999 if (!IS_ERR(name)) {
1000 file = file_open_name(name, flags, mode);
1001 putname(name);
1002 }
1003 return file;
1004}
1005EXPORT_SYMBOL(filp_open);
1006
1007struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
1008 const char *filename, int flags, umode_t mode)
1009{
1010 struct open_flags op;
1011 int err = build_open_flags(flags, mode, &op);
1012 if (err)
1013 return ERR_PTR(err);
1014 return do_file_open_root(dentry, mnt, filename, &op);
1015}
1016EXPORT_SYMBOL(file_open_root);
1017
1018struct file *filp_clone_open(struct file *oldfile)
1019{
1020 struct file *file;
1021 int retval;
1022
1023 file = get_empty_filp();
1024 if (IS_ERR(file))
1025 return file;
1026
1027 file->f_flags = oldfile->f_flags;
1028 retval = vfs_open(&oldfile->f_path, file, oldfile->f_cred);
1029 if (retval) {
1030 put_filp(file);
1031 return ERR_PTR(retval);
1032 }
1033
1034 return file;
1035}
1036EXPORT_SYMBOL(filp_clone_open);
1037
1038long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1039{
1040 struct open_flags op;
1041 int fd = build_open_flags(flags, mode, &op);
1042 struct filename *tmp;
1043
1044 if (fd)
1045 return fd;
1046
1047 tmp = getname(filename);
1048 if (IS_ERR(tmp))
1049 return PTR_ERR(tmp);
1050
1051 fd = get_unused_fd_flags(flags);
1052 if (fd >= 0) {
1053 struct file *f = do_filp_open(dfd, tmp, &op);
1054 if (IS_ERR(f)) {
1055 put_unused_fd(fd);
1056 fd = PTR_ERR(f);
1057 } else {
1058 fsnotify_open(f);
1059 fd_install(fd, f);
1060 }
1061 }
1062 putname(tmp);
1063 return fd;
1064}
1065
1066SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1067{
1068 if (force_o_largefile())
1069 flags |= O_LARGEFILE;
1070
1071 return do_sys_open(AT_FDCWD, filename, flags, mode);
1072}
1073
1074SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1075 umode_t, mode)
1076{
1077 if (force_o_largefile())
1078 flags |= O_LARGEFILE;
1079
1080 return do_sys_open(dfd, filename, flags, mode);
1081}
1082
1083#ifndef __alpha__
1084
1085/*
1086 * For backward compatibility? Maybe this should be moved
1087 * into arch/i386 instead?
1088 */
1089SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1090{
1091 return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1092}
1093
1094#endif
1095
1096/*
1097 * "id" is the POSIX thread ID. We use the
1098 * files pointer for this..
1099 */
1100int filp_close(struct file *filp, fl_owner_t id)
1101{
1102 int retval = 0;
1103
1104 if (!file_count(filp)) {
1105 printk(KERN_ERR "VFS: Close: file count is 0\n");
1106 return 0;
1107 }
1108
1109 if (filp->f_op->flush)
1110 retval = filp->f_op->flush(filp, id);
1111
1112 if (likely(!(filp->f_mode & FMODE_PATH))) {
1113 dnotify_flush(filp, id);
1114 locks_remove_posix(filp, id);
1115 }
1116 fput(filp);
1117 return retval;
1118}
1119
1120EXPORT_SYMBOL(filp_close);
1121
1122/*
1123 * Careful here! We test whether the file pointer is NULL before
1124 * releasing the fd. This ensures that one clone task can't release
1125 * an fd while another clone is opening it.
1126 */
1127SYSCALL_DEFINE1(close, unsigned int, fd)
1128{
1129 int retval = __close_fd(current->files, fd);
1130
1131 /* can't restart close syscall because file table entry was cleared */
1132 if (unlikely(retval == -ERESTARTSYS ||
1133 retval == -ERESTARTNOINTR ||
1134 retval == -ERESTARTNOHAND ||
1135 retval == -ERESTART_RESTARTBLOCK))
1136 retval = -EINTR;
1137
1138 return retval;
1139}
1140EXPORT_SYMBOL(sys_close);
1141
1142/*
1143 * This routine simulates a hangup on the tty, to arrange that users
1144 * are given clean terminals at login time.
1145 */
1146SYSCALL_DEFINE0(vhangup)
1147{
1148 if (capable(CAP_SYS_TTY_CONFIG)) {
1149 tty_vhangup_self();
1150 return 0;
1151 }
1152 return -EPERM;
1153}
1154
1155/*
1156 * Called when an inode is about to be open.
1157 * We use this to disallow opening large files on 32bit systems if
1158 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1159 * on this flag in sys_open.
1160 */
1161int generic_file_open(struct inode * inode, struct file * filp)
1162{
1163 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1164 return -EOVERFLOW;
1165 return 0;
1166}
1167
1168EXPORT_SYMBOL(generic_file_open);
1169
1170/*
1171 * This is used by subsystems that don't want seekable
1172 * file descriptors. The function is not supposed to ever fail, the only
1173 * reason it returns an 'int' and not 'void' is so that it can be plugged
1174 * directly into file_operations structure.
1175 */
1176int nonseekable_open(struct inode *inode, struct file *filp)
1177{
1178 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1179 return 0;
1180}
1181
1182EXPORT_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#include <linux/mnt_idmapping.h>
36
37#include "internal.h"
38
39int do_truncate(struct user_namespace *mnt_userns, struct dentry *dentry,
40 loff_t length, unsigned int time_attrs, struct file *filp)
41{
42 int ret;
43 struct iattr newattrs;
44
45 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
46 if (length < 0)
47 return -EINVAL;
48
49 newattrs.ia_size = length;
50 newattrs.ia_valid = ATTR_SIZE | time_attrs;
51 if (filp) {
52 newattrs.ia_file = filp;
53 newattrs.ia_valid |= ATTR_FILE;
54 }
55
56 /* Remove suid, sgid, and file capabilities on truncate too */
57 ret = dentry_needs_remove_privs(mnt_userns, dentry);
58 if (ret < 0)
59 return ret;
60 if (ret)
61 newattrs.ia_valid |= ret | ATTR_FORCE;
62
63 inode_lock(dentry->d_inode);
64 /* Note any delegations or leases have already been broken: */
65 ret = notify_change(mnt_userns, dentry, &newattrs, NULL);
66 inode_unlock(dentry->d_inode);
67 return ret;
68}
69
70long vfs_truncate(const struct path *path, loff_t length)
71{
72 struct user_namespace *mnt_userns;
73 struct inode *inode;
74 long error;
75
76 inode = path->dentry->d_inode;
77
78 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
79 if (S_ISDIR(inode->i_mode))
80 return -EISDIR;
81 if (!S_ISREG(inode->i_mode))
82 return -EINVAL;
83
84 error = mnt_want_write(path->mnt);
85 if (error)
86 goto out;
87
88 mnt_userns = mnt_user_ns(path->mnt);
89 error = inode_permission(mnt_userns, inode, MAY_WRITE);
90 if (error)
91 goto mnt_drop_write_and_out;
92
93 error = -EPERM;
94 if (IS_APPEND(inode))
95 goto mnt_drop_write_and_out;
96
97 error = get_write_access(inode);
98 if (error)
99 goto mnt_drop_write_and_out;
100
101 /*
102 * Make sure that there are no leases. get_write_access() protects
103 * against the truncate racing with a lease-granting setlease().
104 */
105 error = break_lease(inode, O_WRONLY);
106 if (error)
107 goto put_write_and_out;
108
109 error = security_path_truncate(path);
110 if (!error)
111 error = do_truncate(mnt_userns, path->dentry, length, 0, NULL);
112
113put_write_and_out:
114 put_write_access(inode);
115mnt_drop_write_and_out:
116 mnt_drop_write(path->mnt);
117out:
118 return error;
119}
120EXPORT_SYMBOL_GPL(vfs_truncate);
121
122long do_sys_truncate(const char __user *pathname, loff_t length)
123{
124 unsigned int lookup_flags = LOOKUP_FOLLOW;
125 struct path path;
126 int error;
127
128 if (length < 0) /* sorry, but loff_t says... */
129 return -EINVAL;
130
131retry:
132 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
133 if (!error) {
134 error = vfs_truncate(&path, length);
135 path_put(&path);
136 }
137 if (retry_estale(error, lookup_flags)) {
138 lookup_flags |= LOOKUP_REVAL;
139 goto retry;
140 }
141 return error;
142}
143
144SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
145{
146 return do_sys_truncate(path, length);
147}
148
149#ifdef CONFIG_COMPAT
150COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
151{
152 return do_sys_truncate(path, length);
153}
154#endif
155
156long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
157{
158 struct inode *inode;
159 struct dentry *dentry;
160 struct fd f;
161 int error;
162
163 error = -EINVAL;
164 if (length < 0)
165 goto out;
166 error = -EBADF;
167 f = fdget(fd);
168 if (!f.file)
169 goto out;
170
171 /* explicitly opened as large or we are on 64-bit box */
172 if (f.file->f_flags & O_LARGEFILE)
173 small = 0;
174
175 dentry = f.file->f_path.dentry;
176 inode = dentry->d_inode;
177 error = -EINVAL;
178 if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
179 goto out_putf;
180
181 error = -EINVAL;
182 /* Cannot ftruncate over 2^31 bytes without large file support */
183 if (small && length > MAX_NON_LFS)
184 goto out_putf;
185
186 error = -EPERM;
187 /* Check IS_APPEND on real upper inode */
188 if (IS_APPEND(file_inode(f.file)))
189 goto out_putf;
190 sb_start_write(inode->i_sb);
191 error = security_file_truncate(f.file);
192 if (!error)
193 error = do_truncate(file_mnt_user_ns(f.file), dentry, length,
194 ATTR_MTIME | ATTR_CTIME, f.file);
195 sb_end_write(inode->i_sb);
196out_putf:
197 fdput(f);
198out:
199 return error;
200}
201
202SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
203{
204 return do_sys_ftruncate(fd, length, 1);
205}
206
207#ifdef CONFIG_COMPAT
208COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
209{
210 return do_sys_ftruncate(fd, length, 1);
211}
212#endif
213
214/* LFS versions of truncate are only needed on 32 bit machines */
215#if BITS_PER_LONG == 32
216SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
217{
218 return do_sys_truncate(path, length);
219}
220
221SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
222{
223 return do_sys_ftruncate(fd, length, 0);
224}
225#endif /* BITS_PER_LONG == 32 */
226
227#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64)
228COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname,
229 compat_arg_u64_dual(length))
230{
231 return ksys_truncate(pathname, compat_arg_u64_glue(length));
232}
233#endif
234
235#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64)
236COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd,
237 compat_arg_u64_dual(length))
238{
239 return ksys_ftruncate(fd, compat_arg_u64_glue(length));
240}
241#endif
242
243int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
244{
245 struct inode *inode = file_inode(file);
246 long ret;
247
248 if (offset < 0 || len <= 0)
249 return -EINVAL;
250
251 /* Return error if mode is not supported */
252 if (mode & ~FALLOC_FL_SUPPORTED_MASK)
253 return -EOPNOTSUPP;
254
255 /* Punch hole and zero range are mutually exclusive */
256 if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
257 (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
258 return -EOPNOTSUPP;
259
260 /* Punch hole must have keep size set */
261 if ((mode & FALLOC_FL_PUNCH_HOLE) &&
262 !(mode & FALLOC_FL_KEEP_SIZE))
263 return -EOPNOTSUPP;
264
265 /* Collapse range should only be used exclusively. */
266 if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
267 (mode & ~FALLOC_FL_COLLAPSE_RANGE))
268 return -EINVAL;
269
270 /* Insert range should only be used exclusively. */
271 if ((mode & FALLOC_FL_INSERT_RANGE) &&
272 (mode & ~FALLOC_FL_INSERT_RANGE))
273 return -EINVAL;
274
275 /* Unshare range should only be used with allocate mode. */
276 if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
277 (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
278 return -EINVAL;
279
280 if (!(file->f_mode & FMODE_WRITE))
281 return -EBADF;
282
283 /*
284 * We can only allow pure fallocate on append only files
285 */
286 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
287 return -EPERM;
288
289 if (IS_IMMUTABLE(inode))
290 return -EPERM;
291
292 /*
293 * We cannot allow any fallocate operation on an active swapfile
294 */
295 if (IS_SWAPFILE(inode))
296 return -ETXTBSY;
297
298 /*
299 * Revalidate the write permissions, in case security policy has
300 * changed since the files were opened.
301 */
302 ret = security_file_permission(file, MAY_WRITE);
303 if (ret)
304 return ret;
305
306 if (S_ISFIFO(inode->i_mode))
307 return -ESPIPE;
308
309 if (S_ISDIR(inode->i_mode))
310 return -EISDIR;
311
312 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
313 return -ENODEV;
314
315 /* Check for wrap through zero too */
316 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
317 return -EFBIG;
318
319 if (!file->f_op->fallocate)
320 return -EOPNOTSUPP;
321
322 file_start_write(file);
323 ret = file->f_op->fallocate(file, mode, offset, len);
324
325 /*
326 * Create inotify and fanotify events.
327 *
328 * To keep the logic simple always create events if fallocate succeeds.
329 * This implies that events are even created if the file size remains
330 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
331 */
332 if (ret == 0)
333 fsnotify_modify(file);
334
335 file_end_write(file);
336 return ret;
337}
338EXPORT_SYMBOL_GPL(vfs_fallocate);
339
340int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
341{
342 struct fd f = fdget(fd);
343 int error = -EBADF;
344
345 if (f.file) {
346 error = vfs_fallocate(f.file, mode, offset, len);
347 fdput(f);
348 }
349 return error;
350}
351
352SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
353{
354 return ksys_fallocate(fd, mode, offset, len);
355}
356
357#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE)
358COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset),
359 compat_arg_u64_dual(len))
360{
361 return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset),
362 compat_arg_u64_glue(len));
363}
364#endif
365
366/*
367 * access() needs to use the real uid/gid, not the effective uid/gid.
368 * We do this by temporarily clearing all FS-related capabilities and
369 * switching the fsuid/fsgid around to the real ones.
370 */
371static const struct cred *access_override_creds(void)
372{
373 const struct cred *old_cred;
374 struct cred *override_cred;
375
376 override_cred = prepare_creds();
377 if (!override_cred)
378 return NULL;
379
380 override_cred->fsuid = override_cred->uid;
381 override_cred->fsgid = override_cred->gid;
382
383 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
384 /* Clear the capabilities if we switch to a non-root user */
385 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
386 if (!uid_eq(override_cred->uid, root_uid))
387 cap_clear(override_cred->cap_effective);
388 else
389 override_cred->cap_effective =
390 override_cred->cap_permitted;
391 }
392
393 /*
394 * The new set of credentials can *only* be used in
395 * task-synchronous circumstances, and does not need
396 * RCU freeing, unless somebody then takes a separate
397 * reference to it.
398 *
399 * NOTE! This is _only_ true because this credential
400 * is used purely for override_creds() that installs
401 * it as the subjective cred. Other threads will be
402 * accessing ->real_cred, not the subjective cred.
403 *
404 * If somebody _does_ make a copy of this (using the
405 * 'get_current_cred()' function), that will clear the
406 * non_rcu field, because now that other user may be
407 * expecting RCU freeing. But normal thread-synchronous
408 * cred accesses will keep things non-RCY.
409 */
410 override_cred->non_rcu = 1;
411
412 old_cred = override_creds(override_cred);
413
414 /* override_cred() gets its own ref */
415 put_cred(override_cred);
416
417 return old_cred;
418}
419
420static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
421{
422 struct path path;
423 struct inode *inode;
424 int res;
425 unsigned int lookup_flags = LOOKUP_FOLLOW;
426 const struct cred *old_cred = NULL;
427
428 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
429 return -EINVAL;
430
431 if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
432 return -EINVAL;
433
434 if (flags & AT_SYMLINK_NOFOLLOW)
435 lookup_flags &= ~LOOKUP_FOLLOW;
436 if (flags & AT_EMPTY_PATH)
437 lookup_flags |= LOOKUP_EMPTY;
438
439 if (!(flags & AT_EACCESS)) {
440 old_cred = access_override_creds();
441 if (!old_cred)
442 return -ENOMEM;
443 }
444
445retry:
446 res = user_path_at(dfd, filename, lookup_flags, &path);
447 if (res)
448 goto out;
449
450 inode = d_backing_inode(path.dentry);
451
452 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
453 /*
454 * MAY_EXEC on regular files is denied if the fs is mounted
455 * with the "noexec" flag.
456 */
457 res = -EACCES;
458 if (path_noexec(&path))
459 goto out_path_release;
460 }
461
462 res = inode_permission(mnt_user_ns(path.mnt), inode, mode | MAY_ACCESS);
463 /* SuS v2 requires we report a read only fs too */
464 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
465 goto out_path_release;
466 /*
467 * This is a rare case where using __mnt_is_readonly()
468 * is OK without a mnt_want/drop_write() pair. Since
469 * no actual write to the fs is performed here, we do
470 * not need to telegraph to that to anyone.
471 *
472 * By doing this, we accept that this access is
473 * inherently racy and know that the fs may change
474 * state before we even see this result.
475 */
476 if (__mnt_is_readonly(path.mnt))
477 res = -EROFS;
478
479out_path_release:
480 path_put(&path);
481 if (retry_estale(res, lookup_flags)) {
482 lookup_flags |= LOOKUP_REVAL;
483 goto retry;
484 }
485out:
486 if (old_cred)
487 revert_creds(old_cred);
488
489 return res;
490}
491
492SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
493{
494 return do_faccessat(dfd, filename, mode, 0);
495}
496
497SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
498 int, flags)
499{
500 return do_faccessat(dfd, filename, mode, flags);
501}
502
503SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
504{
505 return do_faccessat(AT_FDCWD, filename, mode, 0);
506}
507
508SYSCALL_DEFINE1(chdir, const char __user *, filename)
509{
510 struct path path;
511 int error;
512 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
513retry:
514 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
515 if (error)
516 goto out;
517
518 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
519 if (error)
520 goto dput_and_out;
521
522 set_fs_pwd(current->fs, &path);
523
524dput_and_out:
525 path_put(&path);
526 if (retry_estale(error, lookup_flags)) {
527 lookup_flags |= LOOKUP_REVAL;
528 goto retry;
529 }
530out:
531 return error;
532}
533
534SYSCALL_DEFINE1(fchdir, unsigned int, fd)
535{
536 struct fd f = fdget_raw(fd);
537 int error;
538
539 error = -EBADF;
540 if (!f.file)
541 goto out;
542
543 error = -ENOTDIR;
544 if (!d_can_lookup(f.file->f_path.dentry))
545 goto out_putf;
546
547 error = file_permission(f.file, MAY_EXEC | MAY_CHDIR);
548 if (!error)
549 set_fs_pwd(current->fs, &f.file->f_path);
550out_putf:
551 fdput(f);
552out:
553 return error;
554}
555
556SYSCALL_DEFINE1(chroot, const char __user *, filename)
557{
558 struct path path;
559 int error;
560 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
561retry:
562 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
563 if (error)
564 goto out;
565
566 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
567 if (error)
568 goto dput_and_out;
569
570 error = -EPERM;
571 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
572 goto dput_and_out;
573 error = security_path_chroot(&path);
574 if (error)
575 goto dput_and_out;
576
577 set_fs_root(current->fs, &path);
578 error = 0;
579dput_and_out:
580 path_put(&path);
581 if (retry_estale(error, lookup_flags)) {
582 lookup_flags |= LOOKUP_REVAL;
583 goto retry;
584 }
585out:
586 return error;
587}
588
589int chmod_common(const struct path *path, umode_t mode)
590{
591 struct inode *inode = path->dentry->d_inode;
592 struct inode *delegated_inode = NULL;
593 struct iattr newattrs;
594 int error;
595
596 error = mnt_want_write(path->mnt);
597 if (error)
598 return error;
599retry_deleg:
600 inode_lock(inode);
601 error = security_path_chmod(path, mode);
602 if (error)
603 goto out_unlock;
604 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
605 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
606 error = notify_change(mnt_user_ns(path->mnt), path->dentry,
607 &newattrs, &delegated_inode);
608out_unlock:
609 inode_unlock(inode);
610 if (delegated_inode) {
611 error = break_deleg_wait(&delegated_inode);
612 if (!error)
613 goto retry_deleg;
614 }
615 mnt_drop_write(path->mnt);
616 return error;
617}
618
619int vfs_fchmod(struct file *file, umode_t mode)
620{
621 audit_file(file);
622 return chmod_common(&file->f_path, mode);
623}
624
625SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
626{
627 struct fd f = fdget(fd);
628 int err = -EBADF;
629
630 if (f.file) {
631 err = vfs_fchmod(f.file, mode);
632 fdput(f);
633 }
634 return err;
635}
636
637static int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
638{
639 struct path path;
640 int error;
641 unsigned int lookup_flags = LOOKUP_FOLLOW;
642retry:
643 error = user_path_at(dfd, filename, lookup_flags, &path);
644 if (!error) {
645 error = chmod_common(&path, mode);
646 path_put(&path);
647 if (retry_estale(error, lookup_flags)) {
648 lookup_flags |= LOOKUP_REVAL;
649 goto retry;
650 }
651 }
652 return error;
653}
654
655SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
656 umode_t, mode)
657{
658 return do_fchmodat(dfd, filename, mode);
659}
660
661SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
662{
663 return do_fchmodat(AT_FDCWD, filename, mode);
664}
665
666/**
667 * setattr_vfsuid - check and set ia_fsuid attribute
668 * @kuid: new inode owner
669 *
670 * Check whether @kuid is valid and if so generate and set vfsuid_t in
671 * ia_vfsuid.
672 *
673 * Return: true if @kuid is valid, false if not.
674 */
675static inline bool setattr_vfsuid(struct iattr *attr, kuid_t kuid)
676{
677 if (!uid_valid(kuid))
678 return false;
679 attr->ia_valid |= ATTR_UID;
680 attr->ia_vfsuid = VFSUIDT_INIT(kuid);
681 return true;
682}
683
684/**
685 * setattr_vfsgid - check and set ia_fsgid attribute
686 * @kgid: new inode owner
687 *
688 * Check whether @kgid is valid and if so generate and set vfsgid_t in
689 * ia_vfsgid.
690 *
691 * Return: true if @kgid is valid, false if not.
692 */
693static inline bool setattr_vfsgid(struct iattr *attr, kgid_t kgid)
694{
695 if (!gid_valid(kgid))
696 return false;
697 attr->ia_valid |= ATTR_GID;
698 attr->ia_vfsgid = VFSGIDT_INIT(kgid);
699 return true;
700}
701
702int chown_common(const struct path *path, uid_t user, gid_t group)
703{
704 struct user_namespace *mnt_userns, *fs_userns;
705 struct inode *inode = path->dentry->d_inode;
706 struct inode *delegated_inode = NULL;
707 int error;
708 struct iattr newattrs;
709 kuid_t uid;
710 kgid_t gid;
711
712 uid = make_kuid(current_user_ns(), user);
713 gid = make_kgid(current_user_ns(), group);
714
715 mnt_userns = mnt_user_ns(path->mnt);
716 fs_userns = i_user_ns(inode);
717
718retry_deleg:
719 newattrs.ia_vfsuid = INVALID_VFSUID;
720 newattrs.ia_vfsgid = INVALID_VFSGID;
721 newattrs.ia_valid = ATTR_CTIME;
722 if ((user != (uid_t)-1) && !setattr_vfsuid(&newattrs, uid))
723 return -EINVAL;
724 if ((group != (gid_t)-1) && !setattr_vfsgid(&newattrs, gid))
725 return -EINVAL;
726 inode_lock(inode);
727 if (!S_ISDIR(inode->i_mode))
728 newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV |
729 setattr_should_drop_sgid(mnt_userns, inode);
730 /* Continue to send actual fs values, not the mount values. */
731 error = security_path_chown(
732 path,
733 from_vfsuid(mnt_userns, fs_userns, newattrs.ia_vfsuid),
734 from_vfsgid(mnt_userns, fs_userns, newattrs.ia_vfsgid));
735 if (!error)
736 error = notify_change(mnt_userns, path->dentry, &newattrs,
737 &delegated_inode);
738 inode_unlock(inode);
739 if (delegated_inode) {
740 error = break_deleg_wait(&delegated_inode);
741 if (!error)
742 goto retry_deleg;
743 }
744 return error;
745}
746
747int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
748 int flag)
749{
750 struct path path;
751 int error = -EINVAL;
752 int lookup_flags;
753
754 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
755 goto out;
756
757 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
758 if (flag & AT_EMPTY_PATH)
759 lookup_flags |= LOOKUP_EMPTY;
760retry:
761 error = user_path_at(dfd, filename, lookup_flags, &path);
762 if (error)
763 goto out;
764 error = mnt_want_write(path.mnt);
765 if (error)
766 goto out_release;
767 error = chown_common(&path, user, group);
768 mnt_drop_write(path.mnt);
769out_release:
770 path_put(&path);
771 if (retry_estale(error, lookup_flags)) {
772 lookup_flags |= LOOKUP_REVAL;
773 goto retry;
774 }
775out:
776 return error;
777}
778
779SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
780 gid_t, group, int, flag)
781{
782 return do_fchownat(dfd, filename, user, group, flag);
783}
784
785SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
786{
787 return do_fchownat(AT_FDCWD, filename, user, group, 0);
788}
789
790SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
791{
792 return do_fchownat(AT_FDCWD, filename, user, group,
793 AT_SYMLINK_NOFOLLOW);
794}
795
796int vfs_fchown(struct file *file, uid_t user, gid_t group)
797{
798 int error;
799
800 error = mnt_want_write_file(file);
801 if (error)
802 return error;
803 audit_file(file);
804 error = chown_common(&file->f_path, user, group);
805 mnt_drop_write_file(file);
806 return error;
807}
808
809int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
810{
811 struct fd f = fdget(fd);
812 int error = -EBADF;
813
814 if (f.file) {
815 error = vfs_fchown(f.file, user, group);
816 fdput(f);
817 }
818 return error;
819}
820
821SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
822{
823 return ksys_fchown(fd, user, group);
824}
825
826static int do_dentry_open(struct file *f,
827 struct inode *inode,
828 int (*open)(struct inode *, struct file *))
829{
830 static const struct file_operations empty_fops = {};
831 int error;
832
833 path_get(&f->f_path);
834 f->f_inode = inode;
835 f->f_mapping = inode->i_mapping;
836 f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
837 f->f_sb_err = file_sample_sb_err(f);
838
839 if (unlikely(f->f_flags & O_PATH)) {
840 f->f_mode = FMODE_PATH | FMODE_OPENED;
841 f->f_op = &empty_fops;
842 return 0;
843 }
844
845 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
846 i_readcount_inc(inode);
847 } else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
848 error = get_write_access(inode);
849 if (unlikely(error))
850 goto cleanup_file;
851 error = __mnt_want_write(f->f_path.mnt);
852 if (unlikely(error)) {
853 put_write_access(inode);
854 goto cleanup_file;
855 }
856 f->f_mode |= FMODE_WRITER;
857 }
858
859 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
860 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
861 f->f_mode |= FMODE_ATOMIC_POS;
862
863 f->f_op = fops_get(inode->i_fop);
864 if (WARN_ON(!f->f_op)) {
865 error = -ENODEV;
866 goto cleanup_all;
867 }
868
869 error = security_file_open(f);
870 if (error)
871 goto cleanup_all;
872
873 error = break_lease(locks_inode(f), f->f_flags);
874 if (error)
875 goto cleanup_all;
876
877 /* normally all 3 are set; ->open() can clear them if needed */
878 f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
879 if (!open)
880 open = f->f_op->open;
881 if (open) {
882 error = open(inode, f);
883 if (error)
884 goto cleanup_all;
885 }
886 f->f_mode |= FMODE_OPENED;
887 if ((f->f_mode & FMODE_READ) &&
888 likely(f->f_op->read || f->f_op->read_iter))
889 f->f_mode |= FMODE_CAN_READ;
890 if ((f->f_mode & FMODE_WRITE) &&
891 likely(f->f_op->write || f->f_op->write_iter))
892 f->f_mode |= FMODE_CAN_WRITE;
893 if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek)
894 f->f_mode &= ~FMODE_LSEEK;
895 if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO)
896 f->f_mode |= FMODE_CAN_ODIRECT;
897
898 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
899 f->f_iocb_flags = iocb_flags(f);
900
901 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
902
903 if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT))
904 return -EINVAL;
905
906 /*
907 * XXX: Huge page cache doesn't support writing yet. Drop all page
908 * cache for this file before processing writes.
909 */
910 if (f->f_mode & FMODE_WRITE) {
911 /*
912 * Paired with smp_mb() in collapse_file() to ensure nr_thps
913 * is up to date and the update to i_writecount by
914 * get_write_access() is visible. Ensures subsequent insertion
915 * of THPs into the page cache will fail.
916 */
917 smp_mb();
918 if (filemap_nr_thps(inode->i_mapping)) {
919 struct address_space *mapping = inode->i_mapping;
920
921 filemap_invalidate_lock(inode->i_mapping);
922 /*
923 * unmap_mapping_range just need to be called once
924 * here, because the private pages is not need to be
925 * unmapped mapping (e.g. data segment of dynamic
926 * shared libraries here).
927 */
928 unmap_mapping_range(mapping, 0, 0, 0);
929 truncate_inode_pages(mapping, 0);
930 filemap_invalidate_unlock(inode->i_mapping);
931 }
932 }
933
934 return 0;
935
936cleanup_all:
937 if (WARN_ON_ONCE(error > 0))
938 error = -EINVAL;
939 fops_put(f->f_op);
940 put_file_access(f);
941cleanup_file:
942 path_put(&f->f_path);
943 f->f_path.mnt = NULL;
944 f->f_path.dentry = NULL;
945 f->f_inode = NULL;
946 return error;
947}
948
949/**
950 * finish_open - finish opening a file
951 * @file: file pointer
952 * @dentry: pointer to dentry
953 * @open: open callback
954 * @opened: state of open
955 *
956 * This can be used to finish opening a file passed to i_op->atomic_open().
957 *
958 * If the open callback is set to NULL, then the standard f_op->open()
959 * filesystem callback is substituted.
960 *
961 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
962 * the return value of d_splice_alias(), then the caller needs to perform dput()
963 * on it after finish_open().
964 *
965 * Returns zero on success or -errno if the open failed.
966 */
967int finish_open(struct file *file, struct dentry *dentry,
968 int (*open)(struct inode *, struct file *))
969{
970 BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
971
972 file->f_path.dentry = dentry;
973 return do_dentry_open(file, d_backing_inode(dentry), open);
974}
975EXPORT_SYMBOL(finish_open);
976
977/**
978 * finish_no_open - finish ->atomic_open() without opening the file
979 *
980 * @file: file pointer
981 * @dentry: dentry or NULL (as returned from ->lookup())
982 *
983 * This can be used to set the result of a successful lookup in ->atomic_open().
984 *
985 * NB: unlike finish_open() this function does consume the dentry reference and
986 * the caller need not dput() it.
987 *
988 * Returns "0" which must be the return value of ->atomic_open() after having
989 * called this function.
990 */
991int finish_no_open(struct file *file, struct dentry *dentry)
992{
993 file->f_path.dentry = dentry;
994 return 0;
995}
996EXPORT_SYMBOL(finish_no_open);
997
998char *file_path(struct file *filp, char *buf, int buflen)
999{
1000 return d_path(&filp->f_path, buf, buflen);
1001}
1002EXPORT_SYMBOL(file_path);
1003
1004/**
1005 * vfs_open - open the file at the given path
1006 * @path: path to open
1007 * @file: newly allocated file with f_flag initialized
1008 * @cred: credentials to use
1009 */
1010int vfs_open(const struct path *path, struct file *file)
1011{
1012 file->f_path = *path;
1013 return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
1014}
1015
1016struct file *dentry_open(const struct path *path, int flags,
1017 const struct cred *cred)
1018{
1019 int error;
1020 struct file *f;
1021
1022 validate_creds(cred);
1023
1024 /* We must always pass in a valid mount pointer. */
1025 BUG_ON(!path->mnt);
1026
1027 f = alloc_empty_file(flags, cred);
1028 if (!IS_ERR(f)) {
1029 error = vfs_open(path, f);
1030 if (error) {
1031 fput(f);
1032 f = ERR_PTR(error);
1033 }
1034 }
1035 return f;
1036}
1037EXPORT_SYMBOL(dentry_open);
1038
1039/**
1040 * dentry_create - Create and open a file
1041 * @path: path to create
1042 * @flags: O_ flags
1043 * @mode: mode bits for new file
1044 * @cred: credentials to use
1045 *
1046 * Caller must hold the parent directory's lock, and have prepared
1047 * a negative dentry, placed in @path->dentry, for the new file.
1048 *
1049 * Caller sets @path->mnt to the vfsmount of the filesystem where
1050 * the new file is to be created. The parent directory and the
1051 * negative dentry must reside on the same filesystem instance.
1052 *
1053 * On success, returns a "struct file *". Otherwise a ERR_PTR
1054 * is returned.
1055 */
1056struct file *dentry_create(const struct path *path, int flags, umode_t mode,
1057 const struct cred *cred)
1058{
1059 struct file *f;
1060 int error;
1061
1062 validate_creds(cred);
1063 f = alloc_empty_file(flags, cred);
1064 if (IS_ERR(f))
1065 return f;
1066
1067 error = vfs_create(mnt_user_ns(path->mnt),
1068 d_inode(path->dentry->d_parent),
1069 path->dentry, mode, true);
1070 if (!error)
1071 error = vfs_open(path, f);
1072
1073 if (unlikely(error)) {
1074 fput(f);
1075 return ERR_PTR(error);
1076 }
1077 return f;
1078}
1079EXPORT_SYMBOL(dentry_create);
1080
1081struct file *open_with_fake_path(const struct path *path, int flags,
1082 struct inode *inode, const struct cred *cred)
1083{
1084 struct file *f = alloc_empty_file_noaccount(flags, cred);
1085 if (!IS_ERR(f)) {
1086 int error;
1087
1088 f->f_path = *path;
1089 error = do_dentry_open(f, inode, NULL);
1090 if (error) {
1091 fput(f);
1092 f = ERR_PTR(error);
1093 }
1094 }
1095 return f;
1096}
1097EXPORT_SYMBOL(open_with_fake_path);
1098
1099#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE))
1100#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
1101
1102inline struct open_how build_open_how(int flags, umode_t mode)
1103{
1104 struct open_how how = {
1105 .flags = flags & VALID_OPEN_FLAGS,
1106 .mode = mode & S_IALLUGO,
1107 };
1108
1109 /* O_PATH beats everything else. */
1110 if (how.flags & O_PATH)
1111 how.flags &= O_PATH_FLAGS;
1112 /* Modes should only be set for create-like flags. */
1113 if (!WILL_CREATE(how.flags))
1114 how.mode = 0;
1115 return how;
1116}
1117
1118inline int build_open_flags(const struct open_how *how, struct open_flags *op)
1119{
1120 u64 flags = how->flags;
1121 u64 strip = FMODE_NONOTIFY | O_CLOEXEC;
1122 int lookup_flags = 0;
1123 int acc_mode = ACC_MODE(flags);
1124
1125 BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
1126 "struct open_flags doesn't yet handle flags > 32 bits");
1127
1128 /*
1129 * Strip flags that either shouldn't be set by userspace like
1130 * FMODE_NONOTIFY or that aren't relevant in determining struct
1131 * open_flags like O_CLOEXEC.
1132 */
1133 flags &= ~strip;
1134
1135 /*
1136 * Older syscalls implicitly clear all of the invalid flags or argument
1137 * values before calling build_open_flags(), but openat2(2) checks all
1138 * of its arguments.
1139 */
1140 if (flags & ~VALID_OPEN_FLAGS)
1141 return -EINVAL;
1142 if (how->resolve & ~VALID_RESOLVE_FLAGS)
1143 return -EINVAL;
1144
1145 /* Scoping flags are mutually exclusive. */
1146 if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
1147 return -EINVAL;
1148
1149 /* Deal with the mode. */
1150 if (WILL_CREATE(flags)) {
1151 if (how->mode & ~S_IALLUGO)
1152 return -EINVAL;
1153 op->mode = how->mode | S_IFREG;
1154 } else {
1155 if (how->mode != 0)
1156 return -EINVAL;
1157 op->mode = 0;
1158 }
1159
1160 /*
1161 * In order to ensure programs get explicit errors when trying to use
1162 * O_TMPFILE on old kernels, O_TMPFILE is implemented such that it
1163 * looks like (O_DIRECTORY|O_RDWR & ~O_CREAT) to old kernels. But we
1164 * have to require userspace to explicitly set it.
1165 */
1166 if (flags & __O_TMPFILE) {
1167 if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
1168 return -EINVAL;
1169 if (!(acc_mode & MAY_WRITE))
1170 return -EINVAL;
1171 }
1172 if (flags & O_PATH) {
1173 /* O_PATH only permits certain other flags to be set. */
1174 if (flags & ~O_PATH_FLAGS)
1175 return -EINVAL;
1176 acc_mode = 0;
1177 }
1178
1179 /*
1180 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1181 * check for O_DSYNC if the need any syncing at all we enforce it's
1182 * always set instead of having to deal with possibly weird behaviour
1183 * for malicious applications setting only __O_SYNC.
1184 */
1185 if (flags & __O_SYNC)
1186 flags |= O_DSYNC;
1187
1188 op->open_flag = flags;
1189
1190 /* O_TRUNC implies we need access checks for write permissions */
1191 if (flags & O_TRUNC)
1192 acc_mode |= MAY_WRITE;
1193
1194 /* Allow the LSM permission hook to distinguish append
1195 access from general write access. */
1196 if (flags & O_APPEND)
1197 acc_mode |= MAY_APPEND;
1198
1199 op->acc_mode = acc_mode;
1200
1201 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1202
1203 if (flags & O_CREAT) {
1204 op->intent |= LOOKUP_CREATE;
1205 if (flags & O_EXCL) {
1206 op->intent |= LOOKUP_EXCL;
1207 flags |= O_NOFOLLOW;
1208 }
1209 }
1210
1211 if (flags & O_DIRECTORY)
1212 lookup_flags |= LOOKUP_DIRECTORY;
1213 if (!(flags & O_NOFOLLOW))
1214 lookup_flags |= LOOKUP_FOLLOW;
1215
1216 if (how->resolve & RESOLVE_NO_XDEV)
1217 lookup_flags |= LOOKUP_NO_XDEV;
1218 if (how->resolve & RESOLVE_NO_MAGICLINKS)
1219 lookup_flags |= LOOKUP_NO_MAGICLINKS;
1220 if (how->resolve & RESOLVE_NO_SYMLINKS)
1221 lookup_flags |= LOOKUP_NO_SYMLINKS;
1222 if (how->resolve & RESOLVE_BENEATH)
1223 lookup_flags |= LOOKUP_BENEATH;
1224 if (how->resolve & RESOLVE_IN_ROOT)
1225 lookup_flags |= LOOKUP_IN_ROOT;
1226 if (how->resolve & RESOLVE_CACHED) {
1227 /* Don't bother even trying for create/truncate/tmpfile open */
1228 if (flags & (O_TRUNC | O_CREAT | O_TMPFILE))
1229 return -EAGAIN;
1230 lookup_flags |= LOOKUP_CACHED;
1231 }
1232
1233 op->lookup_flags = lookup_flags;
1234 return 0;
1235}
1236
1237/**
1238 * file_open_name - open file and return file pointer
1239 *
1240 * @name: struct filename containing path to open
1241 * @flags: open flags as per the open(2) second argument
1242 * @mode: mode for the new file if O_CREAT is set, else ignored
1243 *
1244 * This is the helper to open a file from kernelspace if you really
1245 * have to. But in generally you should not do this, so please move
1246 * along, nothing to see here..
1247 */
1248struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1249{
1250 struct open_flags op;
1251 struct open_how how = build_open_how(flags, mode);
1252 int err = build_open_flags(&how, &op);
1253 if (err)
1254 return ERR_PTR(err);
1255 return do_filp_open(AT_FDCWD, name, &op);
1256}
1257
1258/**
1259 * filp_open - open file and return file pointer
1260 *
1261 * @filename: path to open
1262 * @flags: open flags as per the open(2) second argument
1263 * @mode: mode for the new file if O_CREAT is set, else ignored
1264 *
1265 * This is the helper to open a file from kernelspace if you really
1266 * have to. But in generally you should not do this, so please move
1267 * along, nothing to see here..
1268 */
1269struct file *filp_open(const char *filename, int flags, umode_t mode)
1270{
1271 struct filename *name = getname_kernel(filename);
1272 struct file *file = ERR_CAST(name);
1273
1274 if (!IS_ERR(name)) {
1275 file = file_open_name(name, flags, mode);
1276 putname(name);
1277 }
1278 return file;
1279}
1280EXPORT_SYMBOL(filp_open);
1281
1282struct file *file_open_root(const struct path *root,
1283 const char *filename, int flags, umode_t mode)
1284{
1285 struct open_flags op;
1286 struct open_how how = build_open_how(flags, mode);
1287 int err = build_open_flags(&how, &op);
1288 if (err)
1289 return ERR_PTR(err);
1290 return do_file_open_root(root, filename, &op);
1291}
1292EXPORT_SYMBOL(file_open_root);
1293
1294static long do_sys_openat2(int dfd, const char __user *filename,
1295 struct open_how *how)
1296{
1297 struct open_flags op;
1298 int fd = build_open_flags(how, &op);
1299 struct filename *tmp;
1300
1301 if (fd)
1302 return fd;
1303
1304 tmp = getname(filename);
1305 if (IS_ERR(tmp))
1306 return PTR_ERR(tmp);
1307
1308 fd = get_unused_fd_flags(how->flags);
1309 if (fd >= 0) {
1310 struct file *f = do_filp_open(dfd, tmp, &op);
1311 if (IS_ERR(f)) {
1312 put_unused_fd(fd);
1313 fd = PTR_ERR(f);
1314 } else {
1315 fsnotify_open(f);
1316 fd_install(fd, f);
1317 }
1318 }
1319 putname(tmp);
1320 return fd;
1321}
1322
1323long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1324{
1325 struct open_how how = build_open_how(flags, mode);
1326 return do_sys_openat2(dfd, filename, &how);
1327}
1328
1329
1330SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1331{
1332 if (force_o_largefile())
1333 flags |= O_LARGEFILE;
1334 return do_sys_open(AT_FDCWD, filename, flags, mode);
1335}
1336
1337SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1338 umode_t, mode)
1339{
1340 if (force_o_largefile())
1341 flags |= O_LARGEFILE;
1342 return do_sys_open(dfd, filename, flags, mode);
1343}
1344
1345SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1346 struct open_how __user *, how, size_t, usize)
1347{
1348 int err;
1349 struct open_how tmp;
1350
1351 BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1352 BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1353
1354 if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1355 return -EINVAL;
1356
1357 err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
1358 if (err)
1359 return err;
1360
1361 audit_openat2_how(&tmp);
1362
1363 /* O_LARGEFILE is only allowed for non-O_PATH. */
1364 if (!(tmp.flags & O_PATH) && force_o_largefile())
1365 tmp.flags |= O_LARGEFILE;
1366
1367 return do_sys_openat2(dfd, filename, &tmp);
1368}
1369
1370#ifdef CONFIG_COMPAT
1371/*
1372 * Exactly like sys_open(), except that it doesn't set the
1373 * O_LARGEFILE flag.
1374 */
1375COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1376{
1377 return do_sys_open(AT_FDCWD, filename, flags, mode);
1378}
1379
1380/*
1381 * Exactly like sys_openat(), except that it doesn't set the
1382 * O_LARGEFILE flag.
1383 */
1384COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1385{
1386 return do_sys_open(dfd, filename, flags, mode);
1387}
1388#endif
1389
1390#ifndef __alpha__
1391
1392/*
1393 * For backward compatibility? Maybe this should be moved
1394 * into arch/i386 instead?
1395 */
1396SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1397{
1398 int flags = O_CREAT | O_WRONLY | O_TRUNC;
1399
1400 if (force_o_largefile())
1401 flags |= O_LARGEFILE;
1402 return do_sys_open(AT_FDCWD, pathname, flags, mode);
1403}
1404#endif
1405
1406/*
1407 * "id" is the POSIX thread ID. We use the
1408 * files pointer for this..
1409 */
1410int filp_close(struct file *filp, fl_owner_t id)
1411{
1412 int retval = 0;
1413
1414 if (!file_count(filp)) {
1415 printk(KERN_ERR "VFS: Close: file count is 0\n");
1416 return 0;
1417 }
1418
1419 if (filp->f_op->flush)
1420 retval = filp->f_op->flush(filp, id);
1421
1422 if (likely(!(filp->f_mode & FMODE_PATH))) {
1423 dnotify_flush(filp, id);
1424 locks_remove_posix(filp, id);
1425 }
1426 fput(filp);
1427 return retval;
1428}
1429
1430EXPORT_SYMBOL(filp_close);
1431
1432/*
1433 * Careful here! We test whether the file pointer is NULL before
1434 * releasing the fd. This ensures that one clone task can't release
1435 * an fd while another clone is opening it.
1436 */
1437SYSCALL_DEFINE1(close, unsigned int, fd)
1438{
1439 int retval = close_fd(fd);
1440
1441 /* can't restart close syscall because file table entry was cleared */
1442 if (unlikely(retval == -ERESTARTSYS ||
1443 retval == -ERESTARTNOINTR ||
1444 retval == -ERESTARTNOHAND ||
1445 retval == -ERESTART_RESTARTBLOCK))
1446 retval = -EINTR;
1447
1448 return retval;
1449}
1450
1451/**
1452 * close_range() - Close all file descriptors in a given range.
1453 *
1454 * @fd: starting file descriptor to close
1455 * @max_fd: last file descriptor to close
1456 * @flags: reserved for future extensions
1457 *
1458 * This closes a range of file descriptors. All file descriptors
1459 * from @fd up to and including @max_fd are closed.
1460 * Currently, errors to close a given file descriptor are ignored.
1461 */
1462SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
1463 unsigned int, flags)
1464{
1465 return __close_range(fd, max_fd, flags);
1466}
1467
1468/*
1469 * This routine simulates a hangup on the tty, to arrange that users
1470 * are given clean terminals at login time.
1471 */
1472SYSCALL_DEFINE0(vhangup)
1473{
1474 if (capable(CAP_SYS_TTY_CONFIG)) {
1475 tty_vhangup_self();
1476 return 0;
1477 }
1478 return -EPERM;
1479}
1480
1481/*
1482 * Called when an inode is about to be open.
1483 * We use this to disallow opening large files on 32bit systems if
1484 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1485 * on this flag in sys_open.
1486 */
1487int generic_file_open(struct inode * inode, struct file * filp)
1488{
1489 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1490 return -EOVERFLOW;
1491 return 0;
1492}
1493
1494EXPORT_SYMBOL(generic_file_open);
1495
1496/*
1497 * This is used by subsystems that don't want seekable
1498 * file descriptors. The function is not supposed to ever fail, the only
1499 * reason it returns an 'int' and not 'void' is so that it can be plugged
1500 * directly into file_operations structure.
1501 */
1502int nonseekable_open(struct inode *inode, struct file *filp)
1503{
1504 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1505 return 0;
1506}
1507
1508EXPORT_SYMBOL(nonseekable_open);
1509
1510/*
1511 * stream_open is used by subsystems that want stream-like file descriptors.
1512 * Such file descriptors are not seekable and don't have notion of position
1513 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1514 * Contrary to file descriptors of other regular files, .read() and .write()
1515 * can run simultaneously.
1516 *
1517 * stream_open never fails and is marked to return int so that it could be
1518 * directly used as file_operations.open .
1519 */
1520int stream_open(struct inode *inode, struct file *filp)
1521{
1522 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1523 filp->f_mode |= FMODE_STREAM;
1524 return 0;
1525}
1526
1527EXPORT_SYMBOL(stream_open);