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