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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/dnotify.h>
33#include <linux/compat.h>
34#include <linux/mnt_idmapping.h>
35#include <linux/filelock.h>
36
37#include "internal.h"
38
39int do_truncate(struct mnt_idmap *idmap, 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(idmap, 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(idmap, 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 mnt_idmap *idmap;
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 idmap = mnt_idmap(path->mnt);
89 error = inode_permission(idmap, 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(idmap, 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_ftruncate(struct file *file, loff_t length, int small)
157{
158 struct inode *inode;
159 struct dentry *dentry;
160 int error;
161
162 /* explicitly opened as large or we are on 64-bit box */
163 if (file->f_flags & O_LARGEFILE)
164 small = 0;
165
166 dentry = file->f_path.dentry;
167 inode = dentry->d_inode;
168 if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
169 return -EINVAL;
170
171 /* Cannot ftruncate over 2^31 bytes without large file support */
172 if (small && length > MAX_NON_LFS)
173 return -EINVAL;
174
175 /* Check IS_APPEND on real upper inode */
176 if (IS_APPEND(file_inode(file)))
177 return -EPERM;
178 sb_start_write(inode->i_sb);
179 error = security_file_truncate(file);
180 if (!error)
181 error = do_truncate(file_mnt_idmap(file), dentry, length,
182 ATTR_MTIME | ATTR_CTIME, file);
183 sb_end_write(inode->i_sb);
184
185 return error;
186}
187
188long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
189{
190 struct fd f;
191 int error;
192
193 if (length < 0)
194 return -EINVAL;
195 f = fdget(fd);
196 if (!f.file)
197 return -EBADF;
198
199 error = do_ftruncate(f.file, length, small);
200
201 fdput(f);
202 return error;
203}
204
205SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
206{
207 return do_sys_ftruncate(fd, length, 1);
208}
209
210#ifdef CONFIG_COMPAT
211COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
212{
213 return do_sys_ftruncate(fd, length, 1);
214}
215#endif
216
217/* LFS versions of truncate are only needed on 32 bit machines */
218#if BITS_PER_LONG == 32
219SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
220{
221 return do_sys_truncate(path, length);
222}
223
224SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
225{
226 return do_sys_ftruncate(fd, length, 0);
227}
228#endif /* BITS_PER_LONG == 32 */
229
230#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64)
231COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname,
232 compat_arg_u64_dual(length))
233{
234 return ksys_truncate(pathname, compat_arg_u64_glue(length));
235}
236#endif
237
238#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64)
239COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd,
240 compat_arg_u64_dual(length))
241{
242 return ksys_ftruncate(fd, compat_arg_u64_glue(length));
243}
244#endif
245
246int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
247{
248 struct inode *inode = file_inode(file);
249 long ret;
250
251 if (offset < 0 || len <= 0)
252 return -EINVAL;
253
254 /* Return error if mode is not supported */
255 if (mode & ~FALLOC_FL_SUPPORTED_MASK)
256 return -EOPNOTSUPP;
257
258 /* Punch hole and zero range are mutually exclusive */
259 if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
260 (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
261 return -EOPNOTSUPP;
262
263 /* Punch hole must have keep size set */
264 if ((mode & FALLOC_FL_PUNCH_HOLE) &&
265 !(mode & FALLOC_FL_KEEP_SIZE))
266 return -EOPNOTSUPP;
267
268 /* Collapse range should only be used exclusively. */
269 if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
270 (mode & ~FALLOC_FL_COLLAPSE_RANGE))
271 return -EINVAL;
272
273 /* Insert range should only be used exclusively. */
274 if ((mode & FALLOC_FL_INSERT_RANGE) &&
275 (mode & ~FALLOC_FL_INSERT_RANGE))
276 return -EINVAL;
277
278 /* Unshare range should only be used with allocate mode. */
279 if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
280 (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
281 return -EINVAL;
282
283 if (!(file->f_mode & FMODE_WRITE))
284 return -EBADF;
285
286 /*
287 * We can only allow pure fallocate on append only files
288 */
289 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
290 return -EPERM;
291
292 if (IS_IMMUTABLE(inode))
293 return -EPERM;
294
295 /*
296 * We cannot allow any fallocate operation on an active swapfile
297 */
298 if (IS_SWAPFILE(inode))
299 return -ETXTBSY;
300
301 /*
302 * Revalidate the write permissions, in case security policy has
303 * changed since the files were opened.
304 */
305 ret = security_file_permission(file, MAY_WRITE);
306 if (ret)
307 return ret;
308
309 ret = fsnotify_file_area_perm(file, MAY_WRITE, &offset, len);
310 if (ret)
311 return ret;
312
313 if (S_ISFIFO(inode->i_mode))
314 return -ESPIPE;
315
316 if (S_ISDIR(inode->i_mode))
317 return -EISDIR;
318
319 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
320 return -ENODEV;
321
322 /* Check for wrap through zero too */
323 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
324 return -EFBIG;
325
326 if (!file->f_op->fallocate)
327 return -EOPNOTSUPP;
328
329 file_start_write(file);
330 ret = file->f_op->fallocate(file, mode, offset, len);
331
332 /*
333 * Create inotify and fanotify events.
334 *
335 * To keep the logic simple always create events if fallocate succeeds.
336 * This implies that events are even created if the file size remains
337 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
338 */
339 if (ret == 0)
340 fsnotify_modify(file);
341
342 file_end_write(file);
343 return ret;
344}
345EXPORT_SYMBOL_GPL(vfs_fallocate);
346
347int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
348{
349 struct fd f = fdget(fd);
350 int error = -EBADF;
351
352 if (f.file) {
353 error = vfs_fallocate(f.file, mode, offset, len);
354 fdput(f);
355 }
356 return error;
357}
358
359SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
360{
361 return ksys_fallocate(fd, mode, offset, len);
362}
363
364#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE)
365COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset),
366 compat_arg_u64_dual(len))
367{
368 return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset),
369 compat_arg_u64_glue(len));
370}
371#endif
372
373/*
374 * access() needs to use the real uid/gid, not the effective uid/gid.
375 * We do this by temporarily clearing all FS-related capabilities and
376 * switching the fsuid/fsgid around to the real ones.
377 *
378 * Creating new credentials is expensive, so we try to skip doing it,
379 * which we can if the result would match what we already got.
380 */
381static bool access_need_override_creds(int flags)
382{
383 const struct cred *cred;
384
385 if (flags & AT_EACCESS)
386 return false;
387
388 cred = current_cred();
389 if (!uid_eq(cred->fsuid, cred->uid) ||
390 !gid_eq(cred->fsgid, cred->gid))
391 return true;
392
393 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
394 kuid_t root_uid = make_kuid(cred->user_ns, 0);
395 if (!uid_eq(cred->uid, root_uid)) {
396 if (!cap_isclear(cred->cap_effective))
397 return true;
398 } else {
399 if (!cap_isidentical(cred->cap_effective,
400 cred->cap_permitted))
401 return true;
402 }
403 }
404
405 return false;
406}
407
408static const struct cred *access_override_creds(void)
409{
410 const struct cred *old_cred;
411 struct cred *override_cred;
412
413 override_cred = prepare_creds();
414 if (!override_cred)
415 return NULL;
416
417 /*
418 * XXX access_need_override_creds performs checks in hopes of skipping
419 * this work. Make sure it stays in sync if making any changes in this
420 * routine.
421 */
422
423 override_cred->fsuid = override_cred->uid;
424 override_cred->fsgid = override_cred->gid;
425
426 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
427 /* Clear the capabilities if we switch to a non-root user */
428 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
429 if (!uid_eq(override_cred->uid, root_uid))
430 cap_clear(override_cred->cap_effective);
431 else
432 override_cred->cap_effective =
433 override_cred->cap_permitted;
434 }
435
436 /*
437 * The new set of credentials can *only* be used in
438 * task-synchronous circumstances, and does not need
439 * RCU freeing, unless somebody then takes a separate
440 * reference to it.
441 *
442 * NOTE! This is _only_ true because this credential
443 * is used purely for override_creds() that installs
444 * it as the subjective cred. Other threads will be
445 * accessing ->real_cred, not the subjective cred.
446 *
447 * If somebody _does_ make a copy of this (using the
448 * 'get_current_cred()' function), that will clear the
449 * non_rcu field, because now that other user may be
450 * expecting RCU freeing. But normal thread-synchronous
451 * cred accesses will keep things non-racy to avoid RCU
452 * freeing.
453 */
454 override_cred->non_rcu = 1;
455
456 old_cred = override_creds(override_cred);
457
458 /* override_cred() gets its own ref */
459 put_cred(override_cred);
460
461 return old_cred;
462}
463
464static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
465{
466 struct path path;
467 struct inode *inode;
468 int res;
469 unsigned int lookup_flags = LOOKUP_FOLLOW;
470 const struct cred *old_cred = NULL;
471
472 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
473 return -EINVAL;
474
475 if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
476 return -EINVAL;
477
478 if (flags & AT_SYMLINK_NOFOLLOW)
479 lookup_flags &= ~LOOKUP_FOLLOW;
480 if (flags & AT_EMPTY_PATH)
481 lookup_flags |= LOOKUP_EMPTY;
482
483 if (access_need_override_creds(flags)) {
484 old_cred = access_override_creds();
485 if (!old_cred)
486 return -ENOMEM;
487 }
488
489retry:
490 res = user_path_at(dfd, filename, lookup_flags, &path);
491 if (res)
492 goto out;
493
494 inode = d_backing_inode(path.dentry);
495
496 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
497 /*
498 * MAY_EXEC on regular files is denied if the fs is mounted
499 * with the "noexec" flag.
500 */
501 res = -EACCES;
502 if (path_noexec(&path))
503 goto out_path_release;
504 }
505
506 res = inode_permission(mnt_idmap(path.mnt), inode, mode | MAY_ACCESS);
507 /* SuS v2 requires we report a read only fs too */
508 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
509 goto out_path_release;
510 /*
511 * This is a rare case where using __mnt_is_readonly()
512 * is OK without a mnt_want/drop_write() pair. Since
513 * no actual write to the fs is performed here, we do
514 * not need to telegraph to that to anyone.
515 *
516 * By doing this, we accept that this access is
517 * inherently racy and know that the fs may change
518 * state before we even see this result.
519 */
520 if (__mnt_is_readonly(path.mnt))
521 res = -EROFS;
522
523out_path_release:
524 path_put(&path);
525 if (retry_estale(res, lookup_flags)) {
526 lookup_flags |= LOOKUP_REVAL;
527 goto retry;
528 }
529out:
530 if (old_cred)
531 revert_creds(old_cred);
532
533 return res;
534}
535
536SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
537{
538 return do_faccessat(dfd, filename, mode, 0);
539}
540
541SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
542 int, flags)
543{
544 return do_faccessat(dfd, filename, mode, flags);
545}
546
547SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
548{
549 return do_faccessat(AT_FDCWD, filename, mode, 0);
550}
551
552SYSCALL_DEFINE1(chdir, const char __user *, filename)
553{
554 struct path path;
555 int error;
556 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
557retry:
558 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
559 if (error)
560 goto out;
561
562 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
563 if (error)
564 goto dput_and_out;
565
566 set_fs_pwd(current->fs, &path);
567
568dput_and_out:
569 path_put(&path);
570 if (retry_estale(error, lookup_flags)) {
571 lookup_flags |= LOOKUP_REVAL;
572 goto retry;
573 }
574out:
575 return error;
576}
577
578SYSCALL_DEFINE1(fchdir, unsigned int, fd)
579{
580 struct fd f = fdget_raw(fd);
581 int error;
582
583 error = -EBADF;
584 if (!f.file)
585 goto out;
586
587 error = -ENOTDIR;
588 if (!d_can_lookup(f.file->f_path.dentry))
589 goto out_putf;
590
591 error = file_permission(f.file, MAY_EXEC | MAY_CHDIR);
592 if (!error)
593 set_fs_pwd(current->fs, &f.file->f_path);
594out_putf:
595 fdput(f);
596out:
597 return error;
598}
599
600SYSCALL_DEFINE1(chroot, const char __user *, filename)
601{
602 struct path path;
603 int error;
604 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
605retry:
606 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
607 if (error)
608 goto out;
609
610 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
611 if (error)
612 goto dput_and_out;
613
614 error = -EPERM;
615 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
616 goto dput_and_out;
617 error = security_path_chroot(&path);
618 if (error)
619 goto dput_and_out;
620
621 set_fs_root(current->fs, &path);
622 error = 0;
623dput_and_out:
624 path_put(&path);
625 if (retry_estale(error, lookup_flags)) {
626 lookup_flags |= LOOKUP_REVAL;
627 goto retry;
628 }
629out:
630 return error;
631}
632
633int chmod_common(const struct path *path, umode_t mode)
634{
635 struct inode *inode = path->dentry->d_inode;
636 struct inode *delegated_inode = NULL;
637 struct iattr newattrs;
638 int error;
639
640 error = mnt_want_write(path->mnt);
641 if (error)
642 return error;
643retry_deleg:
644 inode_lock(inode);
645 error = security_path_chmod(path, mode);
646 if (error)
647 goto out_unlock;
648 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
649 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
650 error = notify_change(mnt_idmap(path->mnt), path->dentry,
651 &newattrs, &delegated_inode);
652out_unlock:
653 inode_unlock(inode);
654 if (delegated_inode) {
655 error = break_deleg_wait(&delegated_inode);
656 if (!error)
657 goto retry_deleg;
658 }
659 mnt_drop_write(path->mnt);
660 return error;
661}
662
663int vfs_fchmod(struct file *file, umode_t mode)
664{
665 audit_file(file);
666 return chmod_common(&file->f_path, mode);
667}
668
669SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
670{
671 struct fd f = fdget(fd);
672 int err = -EBADF;
673
674 if (f.file) {
675 err = vfs_fchmod(f.file, mode);
676 fdput(f);
677 }
678 return err;
679}
680
681static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
682 unsigned int flags)
683{
684 struct path path;
685 int error;
686 unsigned int lookup_flags;
687
688 if (unlikely(flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)))
689 return -EINVAL;
690
691 lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
692 if (flags & AT_EMPTY_PATH)
693 lookup_flags |= LOOKUP_EMPTY;
694
695retry:
696 error = user_path_at(dfd, filename, lookup_flags, &path);
697 if (!error) {
698 error = chmod_common(&path, mode);
699 path_put(&path);
700 if (retry_estale(error, lookup_flags)) {
701 lookup_flags |= LOOKUP_REVAL;
702 goto retry;
703 }
704 }
705 return error;
706}
707
708SYSCALL_DEFINE4(fchmodat2, int, dfd, const char __user *, filename,
709 umode_t, mode, unsigned int, flags)
710{
711 return do_fchmodat(dfd, filename, mode, flags);
712}
713
714SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
715 umode_t, mode)
716{
717 return do_fchmodat(dfd, filename, mode, 0);
718}
719
720SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
721{
722 return do_fchmodat(AT_FDCWD, filename, mode, 0);
723}
724
725/*
726 * Check whether @kuid is valid and if so generate and set vfsuid_t in
727 * ia_vfsuid.
728 *
729 * Return: true if @kuid is valid, false if not.
730 */
731static inline bool setattr_vfsuid(struct iattr *attr, kuid_t kuid)
732{
733 if (!uid_valid(kuid))
734 return false;
735 attr->ia_valid |= ATTR_UID;
736 attr->ia_vfsuid = VFSUIDT_INIT(kuid);
737 return true;
738}
739
740/*
741 * Check whether @kgid is valid and if so generate and set vfsgid_t in
742 * ia_vfsgid.
743 *
744 * Return: true if @kgid is valid, false if not.
745 */
746static inline bool setattr_vfsgid(struct iattr *attr, kgid_t kgid)
747{
748 if (!gid_valid(kgid))
749 return false;
750 attr->ia_valid |= ATTR_GID;
751 attr->ia_vfsgid = VFSGIDT_INIT(kgid);
752 return true;
753}
754
755int chown_common(const struct path *path, uid_t user, gid_t group)
756{
757 struct mnt_idmap *idmap;
758 struct user_namespace *fs_userns;
759 struct inode *inode = path->dentry->d_inode;
760 struct inode *delegated_inode = NULL;
761 int error;
762 struct iattr newattrs;
763 kuid_t uid;
764 kgid_t gid;
765
766 uid = make_kuid(current_user_ns(), user);
767 gid = make_kgid(current_user_ns(), group);
768
769 idmap = mnt_idmap(path->mnt);
770 fs_userns = i_user_ns(inode);
771
772retry_deleg:
773 newattrs.ia_vfsuid = INVALID_VFSUID;
774 newattrs.ia_vfsgid = INVALID_VFSGID;
775 newattrs.ia_valid = ATTR_CTIME;
776 if ((user != (uid_t)-1) && !setattr_vfsuid(&newattrs, uid))
777 return -EINVAL;
778 if ((group != (gid_t)-1) && !setattr_vfsgid(&newattrs, gid))
779 return -EINVAL;
780 inode_lock(inode);
781 if (!S_ISDIR(inode->i_mode))
782 newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV |
783 setattr_should_drop_sgid(idmap, inode);
784 /* Continue to send actual fs values, not the mount values. */
785 error = security_path_chown(
786 path,
787 from_vfsuid(idmap, fs_userns, newattrs.ia_vfsuid),
788 from_vfsgid(idmap, fs_userns, newattrs.ia_vfsgid));
789 if (!error)
790 error = notify_change(idmap, path->dentry, &newattrs,
791 &delegated_inode);
792 inode_unlock(inode);
793 if (delegated_inode) {
794 error = break_deleg_wait(&delegated_inode);
795 if (!error)
796 goto retry_deleg;
797 }
798 return error;
799}
800
801int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
802 int flag)
803{
804 struct path path;
805 int error = -EINVAL;
806 int lookup_flags;
807
808 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
809 goto out;
810
811 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
812 if (flag & AT_EMPTY_PATH)
813 lookup_flags |= LOOKUP_EMPTY;
814retry:
815 error = user_path_at(dfd, filename, lookup_flags, &path);
816 if (error)
817 goto out;
818 error = mnt_want_write(path.mnt);
819 if (error)
820 goto out_release;
821 error = chown_common(&path, user, group);
822 mnt_drop_write(path.mnt);
823out_release:
824 path_put(&path);
825 if (retry_estale(error, lookup_flags)) {
826 lookup_flags |= LOOKUP_REVAL;
827 goto retry;
828 }
829out:
830 return error;
831}
832
833SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
834 gid_t, group, int, flag)
835{
836 return do_fchownat(dfd, filename, user, group, flag);
837}
838
839SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
840{
841 return do_fchownat(AT_FDCWD, filename, user, group, 0);
842}
843
844SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
845{
846 return do_fchownat(AT_FDCWD, filename, user, group,
847 AT_SYMLINK_NOFOLLOW);
848}
849
850int vfs_fchown(struct file *file, uid_t user, gid_t group)
851{
852 int error;
853
854 error = mnt_want_write_file(file);
855 if (error)
856 return error;
857 audit_file(file);
858 error = chown_common(&file->f_path, user, group);
859 mnt_drop_write_file(file);
860 return error;
861}
862
863int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
864{
865 struct fd f = fdget(fd);
866 int error = -EBADF;
867
868 if (f.file) {
869 error = vfs_fchown(f.file, user, group);
870 fdput(f);
871 }
872 return error;
873}
874
875SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
876{
877 return ksys_fchown(fd, user, group);
878}
879
880static inline int file_get_write_access(struct file *f)
881{
882 int error;
883
884 error = get_write_access(f->f_inode);
885 if (unlikely(error))
886 return error;
887 error = mnt_get_write_access(f->f_path.mnt);
888 if (unlikely(error))
889 goto cleanup_inode;
890 if (unlikely(f->f_mode & FMODE_BACKING)) {
891 error = mnt_get_write_access(backing_file_user_path(f)->mnt);
892 if (unlikely(error))
893 goto cleanup_mnt;
894 }
895 return 0;
896
897cleanup_mnt:
898 mnt_put_write_access(f->f_path.mnt);
899cleanup_inode:
900 put_write_access(f->f_inode);
901 return error;
902}
903
904static int do_dentry_open(struct file *f,
905 struct inode *inode,
906 int (*open)(struct inode *, struct file *))
907{
908 static const struct file_operations empty_fops = {};
909 int error;
910
911 path_get(&f->f_path);
912 f->f_inode = inode;
913 f->f_mapping = inode->i_mapping;
914 f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
915 f->f_sb_err = file_sample_sb_err(f);
916
917 if (unlikely(f->f_flags & O_PATH)) {
918 f->f_mode = FMODE_PATH | FMODE_OPENED;
919 f->f_op = &empty_fops;
920 return 0;
921 }
922
923 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
924 i_readcount_inc(inode);
925 } else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
926 error = file_get_write_access(f);
927 if (unlikely(error))
928 goto cleanup_file;
929 f->f_mode |= FMODE_WRITER;
930 }
931
932 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
933 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
934 f->f_mode |= FMODE_ATOMIC_POS;
935
936 f->f_op = fops_get(inode->i_fop);
937 if (WARN_ON(!f->f_op)) {
938 error = -ENODEV;
939 goto cleanup_all;
940 }
941
942 error = security_file_open(f);
943 if (error)
944 goto cleanup_all;
945
946 error = break_lease(file_inode(f), f->f_flags);
947 if (error)
948 goto cleanup_all;
949
950 /* normally all 3 are set; ->open() can clear them if needed */
951 f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
952 if (!open)
953 open = f->f_op->open;
954 if (open) {
955 error = open(inode, f);
956 if (error)
957 goto cleanup_all;
958 }
959 f->f_mode |= FMODE_OPENED;
960 if ((f->f_mode & FMODE_READ) &&
961 likely(f->f_op->read || f->f_op->read_iter))
962 f->f_mode |= FMODE_CAN_READ;
963 if ((f->f_mode & FMODE_WRITE) &&
964 likely(f->f_op->write || f->f_op->write_iter))
965 f->f_mode |= FMODE_CAN_WRITE;
966 if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek)
967 f->f_mode &= ~FMODE_LSEEK;
968 if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO)
969 f->f_mode |= FMODE_CAN_ODIRECT;
970
971 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
972 f->f_iocb_flags = iocb_flags(f);
973
974 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
975
976 if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT))
977 return -EINVAL;
978
979 /*
980 * XXX: Huge page cache doesn't support writing yet. Drop all page
981 * cache for this file before processing writes.
982 */
983 if (f->f_mode & FMODE_WRITE) {
984 /*
985 * Paired with smp_mb() in collapse_file() to ensure nr_thps
986 * is up to date and the update to i_writecount by
987 * get_write_access() is visible. Ensures subsequent insertion
988 * of THPs into the page cache will fail.
989 */
990 smp_mb();
991 if (filemap_nr_thps(inode->i_mapping)) {
992 struct address_space *mapping = inode->i_mapping;
993
994 filemap_invalidate_lock(inode->i_mapping);
995 /*
996 * unmap_mapping_range just need to be called once
997 * here, because the private pages is not need to be
998 * unmapped mapping (e.g. data segment of dynamic
999 * shared libraries here).
1000 */
1001 unmap_mapping_range(mapping, 0, 0, 0);
1002 truncate_inode_pages(mapping, 0);
1003 filemap_invalidate_unlock(inode->i_mapping);
1004 }
1005 }
1006
1007 /*
1008 * Once we return a file with FMODE_OPENED, __fput() will call
1009 * fsnotify_close(), so we need fsnotify_open() here for symmetry.
1010 */
1011 fsnotify_open(f);
1012 return 0;
1013
1014cleanup_all:
1015 if (WARN_ON_ONCE(error > 0))
1016 error = -EINVAL;
1017 fops_put(f->f_op);
1018 put_file_access(f);
1019cleanup_file:
1020 path_put(&f->f_path);
1021 f->f_path.mnt = NULL;
1022 f->f_path.dentry = NULL;
1023 f->f_inode = NULL;
1024 return error;
1025}
1026
1027/**
1028 * finish_open - finish opening a file
1029 * @file: file pointer
1030 * @dentry: pointer to dentry
1031 * @open: open callback
1032 *
1033 * This can be used to finish opening a file passed to i_op->atomic_open().
1034 *
1035 * If the open callback is set to NULL, then the standard f_op->open()
1036 * filesystem callback is substituted.
1037 *
1038 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
1039 * the return value of d_splice_alias(), then the caller needs to perform dput()
1040 * on it after finish_open().
1041 *
1042 * Returns zero on success or -errno if the open failed.
1043 */
1044int finish_open(struct file *file, struct dentry *dentry,
1045 int (*open)(struct inode *, struct file *))
1046{
1047 BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
1048
1049 file->f_path.dentry = dentry;
1050 return do_dentry_open(file, d_backing_inode(dentry), open);
1051}
1052EXPORT_SYMBOL(finish_open);
1053
1054/**
1055 * finish_no_open - finish ->atomic_open() without opening the file
1056 *
1057 * @file: file pointer
1058 * @dentry: dentry or NULL (as returned from ->lookup())
1059 *
1060 * This can be used to set the result of a successful lookup in ->atomic_open().
1061 *
1062 * NB: unlike finish_open() this function does consume the dentry reference and
1063 * the caller need not dput() it.
1064 *
1065 * Returns "0" which must be the return value of ->atomic_open() after having
1066 * called this function.
1067 */
1068int finish_no_open(struct file *file, struct dentry *dentry)
1069{
1070 file->f_path.dentry = dentry;
1071 return 0;
1072}
1073EXPORT_SYMBOL(finish_no_open);
1074
1075char *file_path(struct file *filp, char *buf, int buflen)
1076{
1077 return d_path(&filp->f_path, buf, buflen);
1078}
1079EXPORT_SYMBOL(file_path);
1080
1081/**
1082 * vfs_open - open the file at the given path
1083 * @path: path to open
1084 * @file: newly allocated file with f_flag initialized
1085 */
1086int vfs_open(const struct path *path, struct file *file)
1087{
1088 file->f_path = *path;
1089 return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
1090}
1091
1092struct file *dentry_open(const struct path *path, int flags,
1093 const struct cred *cred)
1094{
1095 int error;
1096 struct file *f;
1097
1098 /* We must always pass in a valid mount pointer. */
1099 BUG_ON(!path->mnt);
1100
1101 f = alloc_empty_file(flags, cred);
1102 if (!IS_ERR(f)) {
1103 error = vfs_open(path, f);
1104 if (error) {
1105 fput(f);
1106 f = ERR_PTR(error);
1107 }
1108 }
1109 return f;
1110}
1111EXPORT_SYMBOL(dentry_open);
1112
1113/**
1114 * dentry_create - Create and open a file
1115 * @path: path to create
1116 * @flags: O_ flags
1117 * @mode: mode bits for new file
1118 * @cred: credentials to use
1119 *
1120 * Caller must hold the parent directory's lock, and have prepared
1121 * a negative dentry, placed in @path->dentry, for the new file.
1122 *
1123 * Caller sets @path->mnt to the vfsmount of the filesystem where
1124 * the new file is to be created. The parent directory and the
1125 * negative dentry must reside on the same filesystem instance.
1126 *
1127 * On success, returns a "struct file *". Otherwise a ERR_PTR
1128 * is returned.
1129 */
1130struct file *dentry_create(const struct path *path, int flags, umode_t mode,
1131 const struct cred *cred)
1132{
1133 struct file *f;
1134 int error;
1135
1136 f = alloc_empty_file(flags, cred);
1137 if (IS_ERR(f))
1138 return f;
1139
1140 error = vfs_create(mnt_idmap(path->mnt),
1141 d_inode(path->dentry->d_parent),
1142 path->dentry, mode, true);
1143 if (!error)
1144 error = vfs_open(path, f);
1145
1146 if (unlikely(error)) {
1147 fput(f);
1148 return ERR_PTR(error);
1149 }
1150 return f;
1151}
1152EXPORT_SYMBOL(dentry_create);
1153
1154/**
1155 * kernel_file_open - open a file for kernel internal use
1156 * @path: path of the file to open
1157 * @flags: open flags
1158 * @inode: the inode
1159 * @cred: credentials for open
1160 *
1161 * Open a file for use by in-kernel consumers. The file is not accounted
1162 * against nr_files and must not be installed into the file descriptor
1163 * table.
1164 *
1165 * Return: Opened file on success, an error pointer on failure.
1166 */
1167struct file *kernel_file_open(const struct path *path, int flags,
1168 struct inode *inode, const struct cred *cred)
1169{
1170 struct file *f;
1171 int error;
1172
1173 f = alloc_empty_file_noaccount(flags, cred);
1174 if (IS_ERR(f))
1175 return f;
1176
1177 f->f_path = *path;
1178 error = do_dentry_open(f, inode, NULL);
1179 if (error) {
1180 fput(f);
1181 f = ERR_PTR(error);
1182 }
1183 return f;
1184}
1185EXPORT_SYMBOL_GPL(kernel_file_open);
1186
1187#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE))
1188#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
1189
1190inline struct open_how build_open_how(int flags, umode_t mode)
1191{
1192 struct open_how how = {
1193 .flags = flags & VALID_OPEN_FLAGS,
1194 .mode = mode & S_IALLUGO,
1195 };
1196
1197 /* O_PATH beats everything else. */
1198 if (how.flags & O_PATH)
1199 how.flags &= O_PATH_FLAGS;
1200 /* Modes should only be set for create-like flags. */
1201 if (!WILL_CREATE(how.flags))
1202 how.mode = 0;
1203 return how;
1204}
1205
1206inline int build_open_flags(const struct open_how *how, struct open_flags *op)
1207{
1208 u64 flags = how->flags;
1209 u64 strip = __FMODE_NONOTIFY | O_CLOEXEC;
1210 int lookup_flags = 0;
1211 int acc_mode = ACC_MODE(flags);
1212
1213 BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
1214 "struct open_flags doesn't yet handle flags > 32 bits");
1215
1216 /*
1217 * Strip flags that either shouldn't be set by userspace like
1218 * FMODE_NONOTIFY or that aren't relevant in determining struct
1219 * open_flags like O_CLOEXEC.
1220 */
1221 flags &= ~strip;
1222
1223 /*
1224 * Older syscalls implicitly clear all of the invalid flags or argument
1225 * values before calling build_open_flags(), but openat2(2) checks all
1226 * of its arguments.
1227 */
1228 if (flags & ~VALID_OPEN_FLAGS)
1229 return -EINVAL;
1230 if (how->resolve & ~VALID_RESOLVE_FLAGS)
1231 return -EINVAL;
1232
1233 /* Scoping flags are mutually exclusive. */
1234 if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
1235 return -EINVAL;
1236
1237 /* Deal with the mode. */
1238 if (WILL_CREATE(flags)) {
1239 if (how->mode & ~S_IALLUGO)
1240 return -EINVAL;
1241 op->mode = how->mode | S_IFREG;
1242 } else {
1243 if (how->mode != 0)
1244 return -EINVAL;
1245 op->mode = 0;
1246 }
1247
1248 /*
1249 * Block bugs where O_DIRECTORY | O_CREAT created regular files.
1250 * Note, that blocking O_DIRECTORY | O_CREAT here also protects
1251 * O_TMPFILE below which requires O_DIRECTORY being raised.
1252 */
1253 if ((flags & (O_DIRECTORY | O_CREAT)) == (O_DIRECTORY | O_CREAT))
1254 return -EINVAL;
1255
1256 /* Now handle the creative implementation of O_TMPFILE. */
1257 if (flags & __O_TMPFILE) {
1258 /*
1259 * In order to ensure programs get explicit errors when trying
1260 * to use O_TMPFILE on old kernels we enforce that O_DIRECTORY
1261 * is raised alongside __O_TMPFILE.
1262 */
1263 if (!(flags & O_DIRECTORY))
1264 return -EINVAL;
1265 if (!(acc_mode & MAY_WRITE))
1266 return -EINVAL;
1267 }
1268 if (flags & O_PATH) {
1269 /* O_PATH only permits certain other flags to be set. */
1270 if (flags & ~O_PATH_FLAGS)
1271 return -EINVAL;
1272 acc_mode = 0;
1273 }
1274
1275 /*
1276 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1277 * check for O_DSYNC if the need any syncing at all we enforce it's
1278 * always set instead of having to deal with possibly weird behaviour
1279 * for malicious applications setting only __O_SYNC.
1280 */
1281 if (flags & __O_SYNC)
1282 flags |= O_DSYNC;
1283
1284 op->open_flag = flags;
1285
1286 /* O_TRUNC implies we need access checks for write permissions */
1287 if (flags & O_TRUNC)
1288 acc_mode |= MAY_WRITE;
1289
1290 /* Allow the LSM permission hook to distinguish append
1291 access from general write access. */
1292 if (flags & O_APPEND)
1293 acc_mode |= MAY_APPEND;
1294
1295 op->acc_mode = acc_mode;
1296
1297 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1298
1299 if (flags & O_CREAT) {
1300 op->intent |= LOOKUP_CREATE;
1301 if (flags & O_EXCL) {
1302 op->intent |= LOOKUP_EXCL;
1303 flags |= O_NOFOLLOW;
1304 }
1305 }
1306
1307 if (flags & O_DIRECTORY)
1308 lookup_flags |= LOOKUP_DIRECTORY;
1309 if (!(flags & O_NOFOLLOW))
1310 lookup_flags |= LOOKUP_FOLLOW;
1311
1312 if (how->resolve & RESOLVE_NO_XDEV)
1313 lookup_flags |= LOOKUP_NO_XDEV;
1314 if (how->resolve & RESOLVE_NO_MAGICLINKS)
1315 lookup_flags |= LOOKUP_NO_MAGICLINKS;
1316 if (how->resolve & RESOLVE_NO_SYMLINKS)
1317 lookup_flags |= LOOKUP_NO_SYMLINKS;
1318 if (how->resolve & RESOLVE_BENEATH)
1319 lookup_flags |= LOOKUP_BENEATH;
1320 if (how->resolve & RESOLVE_IN_ROOT)
1321 lookup_flags |= LOOKUP_IN_ROOT;
1322 if (how->resolve & RESOLVE_CACHED) {
1323 /* Don't bother even trying for create/truncate/tmpfile open */
1324 if (flags & (O_TRUNC | O_CREAT | __O_TMPFILE))
1325 return -EAGAIN;
1326 lookup_flags |= LOOKUP_CACHED;
1327 }
1328
1329 op->lookup_flags = lookup_flags;
1330 return 0;
1331}
1332
1333/**
1334 * file_open_name - open file and return file pointer
1335 *
1336 * @name: struct filename containing path to open
1337 * @flags: open flags as per the open(2) second argument
1338 * @mode: mode for the new file if O_CREAT is set, else ignored
1339 *
1340 * This is the helper to open a file from kernelspace if you really
1341 * have to. But in generally you should not do this, so please move
1342 * along, nothing to see here..
1343 */
1344struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1345{
1346 struct open_flags op;
1347 struct open_how how = build_open_how(flags, mode);
1348 int err = build_open_flags(&how, &op);
1349 if (err)
1350 return ERR_PTR(err);
1351 return do_filp_open(AT_FDCWD, name, &op);
1352}
1353
1354/**
1355 * filp_open - open file and return file pointer
1356 *
1357 * @filename: path to open
1358 * @flags: open flags as per the open(2) second argument
1359 * @mode: mode for the new file if O_CREAT is set, else ignored
1360 *
1361 * This is the helper to open a file from kernelspace if you really
1362 * have to. But in generally you should not do this, so please move
1363 * along, nothing to see here..
1364 */
1365struct file *filp_open(const char *filename, int flags, umode_t mode)
1366{
1367 struct filename *name = getname_kernel(filename);
1368 struct file *file = ERR_CAST(name);
1369
1370 if (!IS_ERR(name)) {
1371 file = file_open_name(name, flags, mode);
1372 putname(name);
1373 }
1374 return file;
1375}
1376EXPORT_SYMBOL(filp_open);
1377
1378struct file *file_open_root(const struct path *root,
1379 const char *filename, int flags, umode_t mode)
1380{
1381 struct open_flags op;
1382 struct open_how how = build_open_how(flags, mode);
1383 int err = build_open_flags(&how, &op);
1384 if (err)
1385 return ERR_PTR(err);
1386 return do_file_open_root(root, filename, &op);
1387}
1388EXPORT_SYMBOL(file_open_root);
1389
1390static long do_sys_openat2(int dfd, const char __user *filename,
1391 struct open_how *how)
1392{
1393 struct open_flags op;
1394 int fd = build_open_flags(how, &op);
1395 struct filename *tmp;
1396
1397 if (fd)
1398 return fd;
1399
1400 tmp = getname(filename);
1401 if (IS_ERR(tmp))
1402 return PTR_ERR(tmp);
1403
1404 fd = get_unused_fd_flags(how->flags);
1405 if (fd >= 0) {
1406 struct file *f = do_filp_open(dfd, tmp, &op);
1407 if (IS_ERR(f)) {
1408 put_unused_fd(fd);
1409 fd = PTR_ERR(f);
1410 } else {
1411 fd_install(fd, f);
1412 }
1413 }
1414 putname(tmp);
1415 return fd;
1416}
1417
1418long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1419{
1420 struct open_how how = build_open_how(flags, mode);
1421 return do_sys_openat2(dfd, filename, &how);
1422}
1423
1424
1425SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1426{
1427 if (force_o_largefile())
1428 flags |= O_LARGEFILE;
1429 return do_sys_open(AT_FDCWD, filename, flags, mode);
1430}
1431
1432SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1433 umode_t, mode)
1434{
1435 if (force_o_largefile())
1436 flags |= O_LARGEFILE;
1437 return do_sys_open(dfd, filename, flags, mode);
1438}
1439
1440SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1441 struct open_how __user *, how, size_t, usize)
1442{
1443 int err;
1444 struct open_how tmp;
1445
1446 BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1447 BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1448
1449 if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1450 return -EINVAL;
1451
1452 err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
1453 if (err)
1454 return err;
1455
1456 audit_openat2_how(&tmp);
1457
1458 /* O_LARGEFILE is only allowed for non-O_PATH. */
1459 if (!(tmp.flags & O_PATH) && force_o_largefile())
1460 tmp.flags |= O_LARGEFILE;
1461
1462 return do_sys_openat2(dfd, filename, &tmp);
1463}
1464
1465#ifdef CONFIG_COMPAT
1466/*
1467 * Exactly like sys_open(), except that it doesn't set the
1468 * O_LARGEFILE flag.
1469 */
1470COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1471{
1472 return do_sys_open(AT_FDCWD, filename, flags, mode);
1473}
1474
1475/*
1476 * Exactly like sys_openat(), except that it doesn't set the
1477 * O_LARGEFILE flag.
1478 */
1479COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1480{
1481 return do_sys_open(dfd, filename, flags, mode);
1482}
1483#endif
1484
1485#ifndef __alpha__
1486
1487/*
1488 * For backward compatibility? Maybe this should be moved
1489 * into arch/i386 instead?
1490 */
1491SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1492{
1493 int flags = O_CREAT | O_WRONLY | O_TRUNC;
1494
1495 if (force_o_largefile())
1496 flags |= O_LARGEFILE;
1497 return do_sys_open(AT_FDCWD, pathname, flags, mode);
1498}
1499#endif
1500
1501/*
1502 * "id" is the POSIX thread ID. We use the
1503 * files pointer for this..
1504 */
1505static int filp_flush(struct file *filp, fl_owner_t id)
1506{
1507 int retval = 0;
1508
1509 if (CHECK_DATA_CORRUPTION(file_count(filp) == 0,
1510 "VFS: Close: file count is 0 (f_op=%ps)",
1511 filp->f_op)) {
1512 return 0;
1513 }
1514
1515 if (filp->f_op->flush)
1516 retval = filp->f_op->flush(filp, id);
1517
1518 if (likely(!(filp->f_mode & FMODE_PATH))) {
1519 dnotify_flush(filp, id);
1520 locks_remove_posix(filp, id);
1521 }
1522 return retval;
1523}
1524
1525int filp_close(struct file *filp, fl_owner_t id)
1526{
1527 int retval;
1528
1529 retval = filp_flush(filp, id);
1530 fput(filp);
1531
1532 return retval;
1533}
1534EXPORT_SYMBOL(filp_close);
1535
1536/*
1537 * Careful here! We test whether the file pointer is NULL before
1538 * releasing the fd. This ensures that one clone task can't release
1539 * an fd while another clone is opening it.
1540 */
1541SYSCALL_DEFINE1(close, unsigned int, fd)
1542{
1543 int retval;
1544 struct file *file;
1545
1546 file = file_close_fd(fd);
1547 if (!file)
1548 return -EBADF;
1549
1550 retval = filp_flush(file, current->files);
1551
1552 /*
1553 * We're returning to user space. Don't bother
1554 * with any delayed fput() cases.
1555 */
1556 __fput_sync(file);
1557
1558 /* can't restart close syscall because file table entry was cleared */
1559 if (unlikely(retval == -ERESTARTSYS ||
1560 retval == -ERESTARTNOINTR ||
1561 retval == -ERESTARTNOHAND ||
1562 retval == -ERESTART_RESTARTBLOCK))
1563 retval = -EINTR;
1564
1565 return retval;
1566}
1567
1568/**
1569 * sys_close_range() - Close all file descriptors in a given range.
1570 *
1571 * @fd: starting file descriptor to close
1572 * @max_fd: last file descriptor to close
1573 * @flags: reserved for future extensions
1574 *
1575 * This closes a range of file descriptors. All file descriptors
1576 * from @fd up to and including @max_fd are closed.
1577 * Currently, errors to close a given file descriptor are ignored.
1578 */
1579SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
1580 unsigned int, flags)
1581{
1582 return __close_range(fd, max_fd, flags);
1583}
1584
1585/*
1586 * This routine simulates a hangup on the tty, to arrange that users
1587 * are given clean terminals at login time.
1588 */
1589SYSCALL_DEFINE0(vhangup)
1590{
1591 if (capable(CAP_SYS_TTY_CONFIG)) {
1592 tty_vhangup_self();
1593 return 0;
1594 }
1595 return -EPERM;
1596}
1597
1598/*
1599 * Called when an inode is about to be open.
1600 * We use this to disallow opening large files on 32bit systems if
1601 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1602 * on this flag in sys_open.
1603 */
1604int generic_file_open(struct inode * inode, struct file * filp)
1605{
1606 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1607 return -EOVERFLOW;
1608 return 0;
1609}
1610
1611EXPORT_SYMBOL(generic_file_open);
1612
1613/*
1614 * This is used by subsystems that don't want seekable
1615 * file descriptors. The function is not supposed to ever fail, the only
1616 * reason it returns an 'int' and not 'void' is so that it can be plugged
1617 * directly into file_operations structure.
1618 */
1619int nonseekable_open(struct inode *inode, struct file *filp)
1620{
1621 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1622 return 0;
1623}
1624
1625EXPORT_SYMBOL(nonseekable_open);
1626
1627/*
1628 * stream_open is used by subsystems that want stream-like file descriptors.
1629 * Such file descriptors are not seekable and don't have notion of position
1630 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1631 * Contrary to file descriptors of other regular files, .read() and .write()
1632 * can run simultaneously.
1633 *
1634 * stream_open never fails and is marked to return int so that it could be
1635 * directly used as file_operations.open .
1636 */
1637int stream_open(struct inode *inode, struct file *filp)
1638{
1639 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1640 filp->f_mode |= FMODE_STREAM;
1641 return 0;
1642}
1643
1644EXPORT_SYMBOL(stream_open);