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1/*
2 * linux/fs/open.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7#include <linux/string.h>
8#include <linux/mm.h>
9#include <linux/file.h>
10#include <linux/fdtable.h>
11#include <linux/fsnotify.h>
12#include <linux/module.h>
13#include <linux/tty.h>
14#include <linux/namei.h>
15#include <linux/backing-dev.h>
16#include <linux/capability.h>
17#include <linux/securebits.h>
18#include <linux/security.h>
19#include <linux/mount.h>
20#include <linux/fcntl.h>
21#include <linux/slab.h>
22#include <asm/uaccess.h>
23#include <linux/fs.h>
24#include <linux/personality.h>
25#include <linux/pagemap.h>
26#include <linux/syscalls.h>
27#include <linux/rcupdate.h>
28#include <linux/audit.h>
29#include <linux/falloc.h>
30#include <linux/fs_struct.h>
31#include <linux/ima.h>
32#include <linux/dnotify.h>
33#include <linux/compat.h>
34
35#include "internal.h"
36
37int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
38 struct file *filp)
39{
40 int ret;
41 struct iattr newattrs;
42
43 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
44 if (length < 0)
45 return -EINVAL;
46
47 newattrs.ia_size = length;
48 newattrs.ia_valid = ATTR_SIZE | time_attrs;
49 if (filp) {
50 newattrs.ia_file = filp;
51 newattrs.ia_valid |= ATTR_FILE;
52 }
53
54 /* Remove suid/sgid on truncate too */
55 ret = should_remove_suid(dentry);
56 if (ret)
57 newattrs.ia_valid |= ret | ATTR_FORCE;
58
59 mutex_lock(&dentry->d_inode->i_mutex);
60 /* Note any delegations or leases have already been broken: */
61 ret = notify_change(dentry, &newattrs, NULL);
62 mutex_unlock(&dentry->d_inode->i_mutex);
63 return ret;
64}
65
66long vfs_truncate(struct path *path, loff_t length)
67{
68 struct inode *inode;
69 long error;
70
71 inode = path->dentry->d_inode;
72
73 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
74 if (S_ISDIR(inode->i_mode))
75 return -EISDIR;
76 if (!S_ISREG(inode->i_mode))
77 return -EINVAL;
78
79 error = mnt_want_write(path->mnt);
80 if (error)
81 goto out;
82
83 error = inode_permission(inode, MAY_WRITE);
84 if (error)
85 goto mnt_drop_write_and_out;
86
87 error = -EPERM;
88 if (IS_APPEND(inode))
89 goto mnt_drop_write_and_out;
90
91 error = get_write_access(inode);
92 if (error)
93 goto mnt_drop_write_and_out;
94
95 /*
96 * Make sure that there are no leases. get_write_access() protects
97 * against the truncate racing with a lease-granting setlease().
98 */
99 error = break_lease(inode, O_WRONLY);
100 if (error)
101 goto put_write_and_out;
102
103 error = locks_verify_truncate(inode, NULL, length);
104 if (!error)
105 error = security_path_truncate(path);
106 if (!error)
107 error = do_truncate(path->dentry, length, 0, NULL);
108
109put_write_and_out:
110 put_write_access(inode);
111mnt_drop_write_and_out:
112 mnt_drop_write(path->mnt);
113out:
114 return error;
115}
116EXPORT_SYMBOL_GPL(vfs_truncate);
117
118static long do_sys_truncate(const char __user *pathname, loff_t length)
119{
120 unsigned int lookup_flags = LOOKUP_FOLLOW;
121 struct path path;
122 int error;
123
124 if (length < 0) /* sorry, but loff_t says... */
125 return -EINVAL;
126
127retry:
128 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
129 if (!error) {
130 error = vfs_truncate(&path, length);
131 path_put(&path);
132 }
133 if (retry_estale(error, lookup_flags)) {
134 lookup_flags |= LOOKUP_REVAL;
135 goto retry;
136 }
137 return error;
138}
139
140SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
141{
142 return do_sys_truncate(path, length);
143}
144
145#ifdef CONFIG_COMPAT
146COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
147{
148 return do_sys_truncate(path, length);
149}
150#endif
151
152static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
153{
154 struct inode *inode;
155 struct dentry *dentry;
156 struct fd f;
157 int error;
158
159 error = -EINVAL;
160 if (length < 0)
161 goto out;
162 error = -EBADF;
163 f = fdget(fd);
164 if (!f.file)
165 goto out;
166
167 /* explicitly opened as large or we are on 64-bit box */
168 if (f.file->f_flags & O_LARGEFILE)
169 small = 0;
170
171 dentry = f.file->f_path.dentry;
172 inode = dentry->d_inode;
173 error = -EINVAL;
174 if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
175 goto out_putf;
176
177 error = -EINVAL;
178 /* Cannot ftruncate over 2^31 bytes without large file support */
179 if (small && length > MAX_NON_LFS)
180 goto out_putf;
181
182 error = -EPERM;
183 if (IS_APPEND(inode))
184 goto out_putf;
185
186 sb_start_write(inode->i_sb);
187 error = locks_verify_truncate(inode, f.file, length);
188 if (!error)
189 error = security_path_truncate(&f.file->f_path);
190 if (!error)
191 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
192 sb_end_write(inode->i_sb);
193out_putf:
194 fdput(f);
195out:
196 return error;
197}
198
199SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
200{
201 return do_sys_ftruncate(fd, length, 1);
202}
203
204#ifdef CONFIG_COMPAT
205COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
206{
207 return do_sys_ftruncate(fd, length, 1);
208}
209#endif
210
211/* LFS versions of truncate are only needed on 32 bit machines */
212#if BITS_PER_LONG == 32
213SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
214{
215 return do_sys_truncate(path, length);
216}
217
218SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
219{
220 return do_sys_ftruncate(fd, length, 0);
221}
222#endif /* BITS_PER_LONG == 32 */
223
224
225int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
226{
227 struct inode *inode = file_inode(file);
228 long ret;
229
230 if (offset < 0 || len <= 0)
231 return -EINVAL;
232
233 /* Return error if mode is not supported */
234 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE |
235 FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE))
236 return -EOPNOTSUPP;
237
238 /* Punch hole and zero range are mutually exclusive */
239 if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
240 (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
241 return -EOPNOTSUPP;
242
243 /* Punch hole must have keep size set */
244 if ((mode & FALLOC_FL_PUNCH_HOLE) &&
245 !(mode & FALLOC_FL_KEEP_SIZE))
246 return -EOPNOTSUPP;
247
248 /* Collapse range should only be used exclusively. */
249 if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
250 (mode & ~FALLOC_FL_COLLAPSE_RANGE))
251 return -EINVAL;
252
253 if (!(file->f_mode & FMODE_WRITE))
254 return -EBADF;
255
256 /*
257 * We can only allow pure fallocate on append only files
258 */
259 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
260 return -EPERM;
261
262 if (IS_IMMUTABLE(inode))
263 return -EPERM;
264
265 /*
266 * We can not allow to do any fallocate operation on an active
267 * swapfile
268 */
269 if (IS_SWAPFILE(inode))
270 ret = -ETXTBSY;
271
272 /*
273 * Revalidate the write permissions, in case security policy has
274 * changed since the files were opened.
275 */
276 ret = security_file_permission(file, MAY_WRITE);
277 if (ret)
278 return ret;
279
280 if (S_ISFIFO(inode->i_mode))
281 return -ESPIPE;
282
283 /*
284 * Let individual file system decide if it supports preallocation
285 * for directories or not.
286 */
287 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
288 return -ENODEV;
289
290 /* Check for wrap through zero too */
291 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
292 return -EFBIG;
293
294 if (!file->f_op->fallocate)
295 return -EOPNOTSUPP;
296
297 sb_start_write(inode->i_sb);
298 ret = file->f_op->fallocate(file, mode, offset, len);
299 sb_end_write(inode->i_sb);
300 return ret;
301}
302
303SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
304{
305 struct fd f = fdget(fd);
306 int error = -EBADF;
307
308 if (f.file) {
309 error = do_fallocate(f.file, mode, offset, len);
310 fdput(f);
311 }
312 return error;
313}
314
315/*
316 * access() needs to use the real uid/gid, not the effective uid/gid.
317 * We do this by temporarily clearing all FS-related capabilities and
318 * switching the fsuid/fsgid around to the real ones.
319 */
320SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
321{
322 const struct cred *old_cred;
323 struct cred *override_cred;
324 struct path path;
325 struct inode *inode;
326 int res;
327 unsigned int lookup_flags = LOOKUP_FOLLOW;
328
329 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
330 return -EINVAL;
331
332 override_cred = prepare_creds();
333 if (!override_cred)
334 return -ENOMEM;
335
336 override_cred->fsuid = override_cred->uid;
337 override_cred->fsgid = override_cred->gid;
338
339 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
340 /* Clear the capabilities if we switch to a non-root user */
341 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
342 if (!uid_eq(override_cred->uid, root_uid))
343 cap_clear(override_cred->cap_effective);
344 else
345 override_cred->cap_effective =
346 override_cred->cap_permitted;
347 }
348
349 old_cred = override_creds(override_cred);
350retry:
351 res = user_path_at(dfd, filename, lookup_flags, &path);
352 if (res)
353 goto out;
354
355 inode = path.dentry->d_inode;
356
357 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
358 /*
359 * MAY_EXEC on regular files is denied if the fs is mounted
360 * with the "noexec" flag.
361 */
362 res = -EACCES;
363 if (path.mnt->mnt_flags & MNT_NOEXEC)
364 goto out_path_release;
365 }
366
367 res = inode_permission(inode, mode | MAY_ACCESS);
368 /* SuS v2 requires we report a read only fs too */
369 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
370 goto out_path_release;
371 /*
372 * This is a rare case where using __mnt_is_readonly()
373 * is OK without a mnt_want/drop_write() pair. Since
374 * no actual write to the fs is performed here, we do
375 * not need to telegraph to that to anyone.
376 *
377 * By doing this, we accept that this access is
378 * inherently racy and know that the fs may change
379 * state before we even see this result.
380 */
381 if (__mnt_is_readonly(path.mnt))
382 res = -EROFS;
383
384out_path_release:
385 path_put(&path);
386 if (retry_estale(res, lookup_flags)) {
387 lookup_flags |= LOOKUP_REVAL;
388 goto retry;
389 }
390out:
391 revert_creds(old_cred);
392 put_cred(override_cred);
393 return res;
394}
395
396SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
397{
398 return sys_faccessat(AT_FDCWD, filename, mode);
399}
400
401SYSCALL_DEFINE1(chdir, const char __user *, filename)
402{
403 struct path path;
404 int error;
405 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
406retry:
407 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
408 if (error)
409 goto out;
410
411 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
412 if (error)
413 goto dput_and_out;
414
415 set_fs_pwd(current->fs, &path);
416
417dput_and_out:
418 path_put(&path);
419 if (retry_estale(error, lookup_flags)) {
420 lookup_flags |= LOOKUP_REVAL;
421 goto retry;
422 }
423out:
424 return error;
425}
426
427SYSCALL_DEFINE1(fchdir, unsigned int, fd)
428{
429 struct fd f = fdget_raw(fd);
430 struct inode *inode;
431 int error = -EBADF;
432
433 error = -EBADF;
434 if (!f.file)
435 goto out;
436
437 inode = file_inode(f.file);
438
439 error = -ENOTDIR;
440 if (!S_ISDIR(inode->i_mode))
441 goto out_putf;
442
443 error = inode_permission(inode, MAY_EXEC | MAY_CHDIR);
444 if (!error)
445 set_fs_pwd(current->fs, &f.file->f_path);
446out_putf:
447 fdput(f);
448out:
449 return error;
450}
451
452SYSCALL_DEFINE1(chroot, const char __user *, filename)
453{
454 struct path path;
455 int error;
456 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
457retry:
458 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
459 if (error)
460 goto out;
461
462 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
463 if (error)
464 goto dput_and_out;
465
466 error = -EPERM;
467 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
468 goto dput_and_out;
469 error = security_path_chroot(&path);
470 if (error)
471 goto dput_and_out;
472
473 set_fs_root(current->fs, &path);
474 error = 0;
475dput_and_out:
476 path_put(&path);
477 if (retry_estale(error, lookup_flags)) {
478 lookup_flags |= LOOKUP_REVAL;
479 goto retry;
480 }
481out:
482 return error;
483}
484
485static int chmod_common(struct path *path, umode_t mode)
486{
487 struct inode *inode = path->dentry->d_inode;
488 struct inode *delegated_inode = NULL;
489 struct iattr newattrs;
490 int error;
491
492 error = mnt_want_write(path->mnt);
493 if (error)
494 return error;
495retry_deleg:
496 mutex_lock(&inode->i_mutex);
497 error = security_path_chmod(path, mode);
498 if (error)
499 goto out_unlock;
500 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
501 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
502 error = notify_change(path->dentry, &newattrs, &delegated_inode);
503out_unlock:
504 mutex_unlock(&inode->i_mutex);
505 if (delegated_inode) {
506 error = break_deleg_wait(&delegated_inode);
507 if (!error)
508 goto retry_deleg;
509 }
510 mnt_drop_write(path->mnt);
511 return error;
512}
513
514SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
515{
516 struct fd f = fdget(fd);
517 int err = -EBADF;
518
519 if (f.file) {
520 audit_inode(NULL, f.file->f_path.dentry, 0);
521 err = chmod_common(&f.file->f_path, mode);
522 fdput(f);
523 }
524 return err;
525}
526
527SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode)
528{
529 struct path path;
530 int error;
531 unsigned int lookup_flags = LOOKUP_FOLLOW;
532retry:
533 error = user_path_at(dfd, filename, lookup_flags, &path);
534 if (!error) {
535 error = chmod_common(&path, mode);
536 path_put(&path);
537 if (retry_estale(error, lookup_flags)) {
538 lookup_flags |= LOOKUP_REVAL;
539 goto retry;
540 }
541 }
542 return error;
543}
544
545SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
546{
547 return sys_fchmodat(AT_FDCWD, filename, mode);
548}
549
550static int chown_common(struct path *path, uid_t user, gid_t group)
551{
552 struct inode *inode = path->dentry->d_inode;
553 struct inode *delegated_inode = NULL;
554 int error;
555 struct iattr newattrs;
556 kuid_t uid;
557 kgid_t gid;
558
559 uid = make_kuid(current_user_ns(), user);
560 gid = make_kgid(current_user_ns(), group);
561
562 newattrs.ia_valid = ATTR_CTIME;
563 if (user != (uid_t) -1) {
564 if (!uid_valid(uid))
565 return -EINVAL;
566 newattrs.ia_valid |= ATTR_UID;
567 newattrs.ia_uid = uid;
568 }
569 if (group != (gid_t) -1) {
570 if (!gid_valid(gid))
571 return -EINVAL;
572 newattrs.ia_valid |= ATTR_GID;
573 newattrs.ia_gid = gid;
574 }
575 if (!S_ISDIR(inode->i_mode))
576 newattrs.ia_valid |=
577 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
578retry_deleg:
579 mutex_lock(&inode->i_mutex);
580 error = security_path_chown(path, uid, gid);
581 if (!error)
582 error = notify_change(path->dentry, &newattrs, &delegated_inode);
583 mutex_unlock(&inode->i_mutex);
584 if (delegated_inode) {
585 error = break_deleg_wait(&delegated_inode);
586 if (!error)
587 goto retry_deleg;
588 }
589 return error;
590}
591
592SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
593 gid_t, group, int, flag)
594{
595 struct path path;
596 int error = -EINVAL;
597 int lookup_flags;
598
599 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
600 goto out;
601
602 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
603 if (flag & AT_EMPTY_PATH)
604 lookup_flags |= LOOKUP_EMPTY;
605retry:
606 error = user_path_at(dfd, filename, lookup_flags, &path);
607 if (error)
608 goto out;
609 error = mnt_want_write(path.mnt);
610 if (error)
611 goto out_release;
612 error = chown_common(&path, user, group);
613 mnt_drop_write(path.mnt);
614out_release:
615 path_put(&path);
616 if (retry_estale(error, lookup_flags)) {
617 lookup_flags |= LOOKUP_REVAL;
618 goto retry;
619 }
620out:
621 return error;
622}
623
624SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
625{
626 return sys_fchownat(AT_FDCWD, filename, user, group, 0);
627}
628
629SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
630{
631 return sys_fchownat(AT_FDCWD, filename, user, group,
632 AT_SYMLINK_NOFOLLOW);
633}
634
635SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
636{
637 struct fd f = fdget(fd);
638 int error = -EBADF;
639
640 if (!f.file)
641 goto out;
642
643 error = mnt_want_write_file(f.file);
644 if (error)
645 goto out_fput;
646 audit_inode(NULL, f.file->f_path.dentry, 0);
647 error = chown_common(&f.file->f_path, user, group);
648 mnt_drop_write_file(f.file);
649out_fput:
650 fdput(f);
651out:
652 return error;
653}
654
655int open_check_o_direct(struct file *f)
656{
657 /* NB: we're sure to have correct a_ops only after f_op->open */
658 if (f->f_flags & O_DIRECT) {
659 if (!f->f_mapping->a_ops ||
660 ((!f->f_mapping->a_ops->direct_IO) &&
661 (!f->f_mapping->a_ops->get_xip_mem))) {
662 return -EINVAL;
663 }
664 }
665 return 0;
666}
667
668static int do_dentry_open(struct file *f,
669 int (*open)(struct inode *, struct file *),
670 const struct cred *cred)
671{
672 static const struct file_operations empty_fops = {};
673 struct inode *inode;
674 int error;
675
676 f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
677 FMODE_PREAD | FMODE_PWRITE;
678
679 path_get(&f->f_path);
680 inode = f->f_inode = f->f_path.dentry->d_inode;
681 f->f_mapping = inode->i_mapping;
682
683 if (unlikely(f->f_flags & O_PATH)) {
684 f->f_mode = FMODE_PATH;
685 f->f_op = &empty_fops;
686 return 0;
687 }
688
689 if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
690 error = get_write_access(inode);
691 if (unlikely(error))
692 goto cleanup_file;
693 error = __mnt_want_write(f->f_path.mnt);
694 if (unlikely(error)) {
695 put_write_access(inode);
696 goto cleanup_file;
697 }
698 f->f_mode |= FMODE_WRITER;
699 }
700
701 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
702 if (S_ISREG(inode->i_mode))
703 f->f_mode |= FMODE_ATOMIC_POS;
704
705 f->f_op = fops_get(inode->i_fop);
706 if (unlikely(WARN_ON(!f->f_op))) {
707 error = -ENODEV;
708 goto cleanup_all;
709 }
710
711 error = security_file_open(f, cred);
712 if (error)
713 goto cleanup_all;
714
715 error = break_lease(inode, f->f_flags);
716 if (error)
717 goto cleanup_all;
718
719 if (!open)
720 open = f->f_op->open;
721 if (open) {
722 error = open(inode, f);
723 if (error)
724 goto cleanup_all;
725 }
726 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
727 i_readcount_inc(inode);
728
729 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
730
731 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
732
733 return 0;
734
735cleanup_all:
736 fops_put(f->f_op);
737 if (f->f_mode & FMODE_WRITER) {
738 put_write_access(inode);
739 __mnt_drop_write(f->f_path.mnt);
740 }
741cleanup_file:
742 path_put(&f->f_path);
743 f->f_path.mnt = NULL;
744 f->f_path.dentry = NULL;
745 f->f_inode = NULL;
746 return error;
747}
748
749/**
750 * finish_open - finish opening a file
751 * @file: file pointer
752 * @dentry: pointer to dentry
753 * @open: open callback
754 * @opened: state of open
755 *
756 * This can be used to finish opening a file passed to i_op->atomic_open().
757 *
758 * If the open callback is set to NULL, then the standard f_op->open()
759 * filesystem callback is substituted.
760 *
761 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
762 * the return value of d_splice_alias(), then the caller needs to perform dput()
763 * on it after finish_open().
764 *
765 * On successful return @file is a fully instantiated open file. After this, if
766 * an error occurs in ->atomic_open(), it needs to clean up with fput().
767 *
768 * Returns zero on success or -errno if the open failed.
769 */
770int finish_open(struct file *file, struct dentry *dentry,
771 int (*open)(struct inode *, struct file *),
772 int *opened)
773{
774 int error;
775 BUG_ON(*opened & FILE_OPENED); /* once it's opened, it's opened */
776
777 file->f_path.dentry = dentry;
778 error = do_dentry_open(file, open, current_cred());
779 if (!error)
780 *opened |= FILE_OPENED;
781
782 return error;
783}
784EXPORT_SYMBOL(finish_open);
785
786/**
787 * finish_no_open - finish ->atomic_open() without opening the file
788 *
789 * @file: file pointer
790 * @dentry: dentry or NULL (as returned from ->lookup())
791 *
792 * This can be used to set the result of a successful lookup in ->atomic_open().
793 *
794 * NB: unlike finish_open() this function does consume the dentry reference and
795 * the caller need not dput() it.
796 *
797 * Returns "1" which must be the return value of ->atomic_open() after having
798 * called this function.
799 */
800int finish_no_open(struct file *file, struct dentry *dentry)
801{
802 file->f_path.dentry = dentry;
803 return 1;
804}
805EXPORT_SYMBOL(finish_no_open);
806
807struct file *dentry_open(const struct path *path, int flags,
808 const struct cred *cred)
809{
810 int error;
811 struct file *f;
812
813 validate_creds(cred);
814
815 /* We must always pass in a valid mount pointer. */
816 BUG_ON(!path->mnt);
817
818 f = get_empty_filp();
819 if (!IS_ERR(f)) {
820 f->f_flags = flags;
821 f->f_path = *path;
822 error = do_dentry_open(f, NULL, cred);
823 if (!error) {
824 /* from now on we need fput() to dispose of f */
825 error = open_check_o_direct(f);
826 if (error) {
827 fput(f);
828 f = ERR_PTR(error);
829 }
830 } else {
831 put_filp(f);
832 f = ERR_PTR(error);
833 }
834 }
835 return f;
836}
837EXPORT_SYMBOL(dentry_open);
838
839static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
840{
841 int lookup_flags = 0;
842 int acc_mode;
843
844 if (flags & (O_CREAT | __O_TMPFILE))
845 op->mode = (mode & S_IALLUGO) | S_IFREG;
846 else
847 op->mode = 0;
848
849 /* Must never be set by userspace */
850 flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC;
851
852 /*
853 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
854 * check for O_DSYNC if the need any syncing at all we enforce it's
855 * always set instead of having to deal with possibly weird behaviour
856 * for malicious applications setting only __O_SYNC.
857 */
858 if (flags & __O_SYNC)
859 flags |= O_DSYNC;
860
861 if (flags & __O_TMPFILE) {
862 if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
863 return -EINVAL;
864 acc_mode = MAY_OPEN | ACC_MODE(flags);
865 if (!(acc_mode & MAY_WRITE))
866 return -EINVAL;
867 } else if (flags & O_PATH) {
868 /*
869 * If we have O_PATH in the open flag. Then we
870 * cannot have anything other than the below set of flags
871 */
872 flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
873 acc_mode = 0;
874 } else {
875 acc_mode = MAY_OPEN | ACC_MODE(flags);
876 }
877
878 op->open_flag = flags;
879
880 /* O_TRUNC implies we need access checks for write permissions */
881 if (flags & O_TRUNC)
882 acc_mode |= MAY_WRITE;
883
884 /* Allow the LSM permission hook to distinguish append
885 access from general write access. */
886 if (flags & O_APPEND)
887 acc_mode |= MAY_APPEND;
888
889 op->acc_mode = acc_mode;
890
891 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
892
893 if (flags & O_CREAT) {
894 op->intent |= LOOKUP_CREATE;
895 if (flags & O_EXCL)
896 op->intent |= LOOKUP_EXCL;
897 }
898
899 if (flags & O_DIRECTORY)
900 lookup_flags |= LOOKUP_DIRECTORY;
901 if (!(flags & O_NOFOLLOW))
902 lookup_flags |= LOOKUP_FOLLOW;
903 op->lookup_flags = lookup_flags;
904 return 0;
905}
906
907/**
908 * file_open_name - open file and return file pointer
909 *
910 * @name: struct filename containing path to open
911 * @flags: open flags as per the open(2) second argument
912 * @mode: mode for the new file if O_CREAT is set, else ignored
913 *
914 * This is the helper to open a file from kernelspace if you really
915 * have to. But in generally you should not do this, so please move
916 * along, nothing to see here..
917 */
918struct file *file_open_name(struct filename *name, int flags, umode_t mode)
919{
920 struct open_flags op;
921 int err = build_open_flags(flags, mode, &op);
922 return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &op);
923}
924
925/**
926 * filp_open - open file and return file pointer
927 *
928 * @filename: path to open
929 * @flags: open flags as per the open(2) second argument
930 * @mode: mode for the new file if O_CREAT is set, else ignored
931 *
932 * This is the helper to open a file from kernelspace if you really
933 * have to. But in generally you should not do this, so please move
934 * along, nothing to see here..
935 */
936struct file *filp_open(const char *filename, int flags, umode_t mode)
937{
938 struct filename name = {.name = filename};
939 return file_open_name(&name, flags, mode);
940}
941EXPORT_SYMBOL(filp_open);
942
943struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
944 const char *filename, int flags)
945{
946 struct open_flags op;
947 int err = build_open_flags(flags, 0, &op);
948 if (err)
949 return ERR_PTR(err);
950 if (flags & O_CREAT)
951 return ERR_PTR(-EINVAL);
952 if (!filename && (flags & O_DIRECTORY))
953 if (!dentry->d_inode->i_op->lookup)
954 return ERR_PTR(-ENOTDIR);
955 return do_file_open_root(dentry, mnt, filename, &op);
956}
957EXPORT_SYMBOL(file_open_root);
958
959long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
960{
961 struct open_flags op;
962 int fd = build_open_flags(flags, mode, &op);
963 struct filename *tmp;
964
965 if (fd)
966 return fd;
967
968 tmp = getname(filename);
969 if (IS_ERR(tmp))
970 return PTR_ERR(tmp);
971
972 fd = get_unused_fd_flags(flags);
973 if (fd >= 0) {
974 struct file *f = do_filp_open(dfd, tmp, &op);
975 if (IS_ERR(f)) {
976 put_unused_fd(fd);
977 fd = PTR_ERR(f);
978 } else {
979 fsnotify_open(f);
980 fd_install(fd, f);
981 }
982 }
983 putname(tmp);
984 return fd;
985}
986
987SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
988{
989 if (force_o_largefile())
990 flags |= O_LARGEFILE;
991
992 return do_sys_open(AT_FDCWD, filename, flags, mode);
993}
994
995SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
996 umode_t, mode)
997{
998 if (force_o_largefile())
999 flags |= O_LARGEFILE;
1000
1001 return do_sys_open(dfd, filename, flags, mode);
1002}
1003
1004#ifndef __alpha__
1005
1006/*
1007 * For backward compatibility? Maybe this should be moved
1008 * into arch/i386 instead?
1009 */
1010SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1011{
1012 return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1013}
1014
1015#endif
1016
1017/*
1018 * "id" is the POSIX thread ID. We use the
1019 * files pointer for this..
1020 */
1021int filp_close(struct file *filp, fl_owner_t id)
1022{
1023 int retval = 0;
1024
1025 if (!file_count(filp)) {
1026 printk(KERN_ERR "VFS: Close: file count is 0\n");
1027 return 0;
1028 }
1029
1030 if (filp->f_op->flush)
1031 retval = filp->f_op->flush(filp, id);
1032
1033 if (likely(!(filp->f_mode & FMODE_PATH))) {
1034 dnotify_flush(filp, id);
1035 locks_remove_posix(filp, id);
1036 }
1037 fput(filp);
1038 return retval;
1039}
1040
1041EXPORT_SYMBOL(filp_close);
1042
1043/*
1044 * Careful here! We test whether the file pointer is NULL before
1045 * releasing the fd. This ensures that one clone task can't release
1046 * an fd while another clone is opening it.
1047 */
1048SYSCALL_DEFINE1(close, unsigned int, fd)
1049{
1050 int retval = __close_fd(current->files, fd);
1051
1052 /* can't restart close syscall because file table entry was cleared */
1053 if (unlikely(retval == -ERESTARTSYS ||
1054 retval == -ERESTARTNOINTR ||
1055 retval == -ERESTARTNOHAND ||
1056 retval == -ERESTART_RESTARTBLOCK))
1057 retval = -EINTR;
1058
1059 return retval;
1060}
1061EXPORT_SYMBOL(sys_close);
1062
1063/*
1064 * This routine simulates a hangup on the tty, to arrange that users
1065 * are given clean terminals at login time.
1066 */
1067SYSCALL_DEFINE0(vhangup)
1068{
1069 if (capable(CAP_SYS_TTY_CONFIG)) {
1070 tty_vhangup_self();
1071 return 0;
1072 }
1073 return -EPERM;
1074}
1075
1076/*
1077 * Called when an inode is about to be open.
1078 * We use this to disallow opening large files on 32bit systems if
1079 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1080 * on this flag in sys_open.
1081 */
1082int generic_file_open(struct inode * inode, struct file * filp)
1083{
1084 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1085 return -EOVERFLOW;
1086 return 0;
1087}
1088
1089EXPORT_SYMBOL(generic_file_open);
1090
1091/*
1092 * This is used by subsystems that don't want seekable
1093 * file descriptors. The function is not supposed to ever fail, the only
1094 * reason it returns an 'int' and not 'void' is so that it can be plugged
1095 * directly into file_operations structure.
1096 */
1097int nonseekable_open(struct inode *inode, struct file *filp)
1098{
1099 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1100 return 0;
1101}
1102
1103EXPORT_SYMBOL(nonseekable_open);
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/open.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8#include <linux/string.h>
9#include <linux/mm.h>
10#include <linux/file.h>
11#include <linux/fdtable.h>
12#include <linux/fsnotify.h>
13#include <linux/module.h>
14#include <linux/tty.h>
15#include <linux/namei.h>
16#include <linux/backing-dev.h>
17#include <linux/capability.h>
18#include <linux/securebits.h>
19#include <linux/security.h>
20#include <linux/mount.h>
21#include <linux/fcntl.h>
22#include <linux/slab.h>
23#include <linux/uaccess.h>
24#include <linux/fs.h>
25#include <linux/personality.h>
26#include <linux/pagemap.h>
27#include <linux/syscalls.h>
28#include <linux/rcupdate.h>
29#include <linux/audit.h>
30#include <linux/falloc.h>
31#include <linux/fs_struct.h>
32#include <linux/ima.h>
33#include <linux/dnotify.h>
34#include <linux/compat.h>
35
36#include "internal.h"
37
38int do_truncate(struct user_namespace *mnt_userns, struct dentry *dentry,
39 loff_t length, unsigned int time_attrs, struct file *filp)
40{
41 int ret;
42 struct iattr newattrs;
43
44 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
45 if (length < 0)
46 return -EINVAL;
47
48 newattrs.ia_size = length;
49 newattrs.ia_valid = ATTR_SIZE | time_attrs;
50 if (filp) {
51 newattrs.ia_file = filp;
52 newattrs.ia_valid |= ATTR_FILE;
53 }
54
55 /* Remove suid, sgid, and file capabilities on truncate too */
56 ret = dentry_needs_remove_privs(dentry);
57 if (ret < 0)
58 return ret;
59 if (ret)
60 newattrs.ia_valid |= ret | ATTR_FORCE;
61
62 inode_lock(dentry->d_inode);
63 /* Note any delegations or leases have already been broken: */
64 ret = notify_change(mnt_userns, dentry, &newattrs, NULL);
65 inode_unlock(dentry->d_inode);
66 return ret;
67}
68
69long vfs_truncate(const struct path *path, loff_t length)
70{
71 struct user_namespace *mnt_userns;
72 struct inode *inode;
73 long error;
74
75 inode = path->dentry->d_inode;
76
77 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
78 if (S_ISDIR(inode->i_mode))
79 return -EISDIR;
80 if (!S_ISREG(inode->i_mode))
81 return -EINVAL;
82
83 error = mnt_want_write(path->mnt);
84 if (error)
85 goto out;
86
87 mnt_userns = mnt_user_ns(path->mnt);
88 error = inode_permission(mnt_userns, inode, MAY_WRITE);
89 if (error)
90 goto mnt_drop_write_and_out;
91
92 error = -EPERM;
93 if (IS_APPEND(inode))
94 goto mnt_drop_write_and_out;
95
96 error = get_write_access(inode);
97 if (error)
98 goto mnt_drop_write_and_out;
99
100 /*
101 * Make sure that there are no leases. get_write_access() protects
102 * against the truncate racing with a lease-granting setlease().
103 */
104 error = break_lease(inode, O_WRONLY);
105 if (error)
106 goto put_write_and_out;
107
108 error = locks_verify_truncate(inode, NULL, length);
109 if (!error)
110 error = security_path_truncate(path);
111 if (!error)
112 error = do_truncate(mnt_userns, path->dentry, length, 0, NULL);
113
114put_write_and_out:
115 put_write_access(inode);
116mnt_drop_write_and_out:
117 mnt_drop_write(path->mnt);
118out:
119 return error;
120}
121EXPORT_SYMBOL_GPL(vfs_truncate);
122
123long do_sys_truncate(const char __user *pathname, loff_t length)
124{
125 unsigned int lookup_flags = LOOKUP_FOLLOW;
126 struct path path;
127 int error;
128
129 if (length < 0) /* sorry, but loff_t says... */
130 return -EINVAL;
131
132retry:
133 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
134 if (!error) {
135 error = vfs_truncate(&path, length);
136 path_put(&path);
137 }
138 if (retry_estale(error, lookup_flags)) {
139 lookup_flags |= LOOKUP_REVAL;
140 goto retry;
141 }
142 return error;
143}
144
145SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
146{
147 return do_sys_truncate(path, length);
148}
149
150#ifdef CONFIG_COMPAT
151COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
152{
153 return do_sys_truncate(path, length);
154}
155#endif
156
157long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
158{
159 struct inode *inode;
160 struct dentry *dentry;
161 struct fd f;
162 int error;
163
164 error = -EINVAL;
165 if (length < 0)
166 goto out;
167 error = -EBADF;
168 f = fdget(fd);
169 if (!f.file)
170 goto out;
171
172 /* explicitly opened as large or we are on 64-bit box */
173 if (f.file->f_flags & O_LARGEFILE)
174 small = 0;
175
176 dentry = f.file->f_path.dentry;
177 inode = dentry->d_inode;
178 error = -EINVAL;
179 if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
180 goto out_putf;
181
182 error = -EINVAL;
183 /* Cannot ftruncate over 2^31 bytes without large file support */
184 if (small && length > MAX_NON_LFS)
185 goto out_putf;
186
187 error = -EPERM;
188 /* Check IS_APPEND on real upper inode */
189 if (IS_APPEND(file_inode(f.file)))
190 goto out_putf;
191 sb_start_write(inode->i_sb);
192 error = locks_verify_truncate(inode, f.file, length);
193 if (!error)
194 error = security_path_truncate(&f.file->f_path);
195 if (!error)
196 error = do_truncate(file_mnt_user_ns(f.file), dentry, length,
197 ATTR_MTIME | ATTR_CTIME, f.file);
198 sb_end_write(inode->i_sb);
199out_putf:
200 fdput(f);
201out:
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
231int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
232{
233 struct inode *inode = file_inode(file);
234 long ret;
235
236 if (offset < 0 || len <= 0)
237 return -EINVAL;
238
239 /* Return error if mode is not supported */
240 if (mode & ~FALLOC_FL_SUPPORTED_MASK)
241 return -EOPNOTSUPP;
242
243 /* Punch hole and zero range are mutually exclusive */
244 if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
245 (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
246 return -EOPNOTSUPP;
247
248 /* Punch hole must have keep size set */
249 if ((mode & FALLOC_FL_PUNCH_HOLE) &&
250 !(mode & FALLOC_FL_KEEP_SIZE))
251 return -EOPNOTSUPP;
252
253 /* Collapse range should only be used exclusively. */
254 if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
255 (mode & ~FALLOC_FL_COLLAPSE_RANGE))
256 return -EINVAL;
257
258 /* Insert range should only be used exclusively. */
259 if ((mode & FALLOC_FL_INSERT_RANGE) &&
260 (mode & ~FALLOC_FL_INSERT_RANGE))
261 return -EINVAL;
262
263 /* Unshare range should only be used with allocate mode. */
264 if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
265 (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
266 return -EINVAL;
267
268 if (!(file->f_mode & FMODE_WRITE))
269 return -EBADF;
270
271 /*
272 * We can only allow pure fallocate on append only files
273 */
274 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
275 return -EPERM;
276
277 if (IS_IMMUTABLE(inode))
278 return -EPERM;
279
280 /*
281 * We cannot allow any fallocate operation on an active swapfile
282 */
283 if (IS_SWAPFILE(inode))
284 return -ETXTBSY;
285
286 /*
287 * Revalidate the write permissions, in case security policy has
288 * changed since the files were opened.
289 */
290 ret = security_file_permission(file, MAY_WRITE);
291 if (ret)
292 return ret;
293
294 if (S_ISFIFO(inode->i_mode))
295 return -ESPIPE;
296
297 if (S_ISDIR(inode->i_mode))
298 return -EISDIR;
299
300 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
301 return -ENODEV;
302
303 /* Check for wrap through zero too */
304 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
305 return -EFBIG;
306
307 if (!file->f_op->fallocate)
308 return -EOPNOTSUPP;
309
310 file_start_write(file);
311 ret = file->f_op->fallocate(file, mode, offset, len);
312
313 /*
314 * Create inotify and fanotify events.
315 *
316 * To keep the logic simple always create events if fallocate succeeds.
317 * This implies that events are even created if the file size remains
318 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
319 */
320 if (ret == 0)
321 fsnotify_modify(file);
322
323 file_end_write(file);
324 return ret;
325}
326EXPORT_SYMBOL_GPL(vfs_fallocate);
327
328int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
329{
330 struct fd f = fdget(fd);
331 int error = -EBADF;
332
333 if (f.file) {
334 error = vfs_fallocate(f.file, mode, offset, len);
335 fdput(f);
336 }
337 return error;
338}
339
340SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
341{
342 return ksys_fallocate(fd, mode, offset, len);
343}
344
345/*
346 * access() needs to use the real uid/gid, not the effective uid/gid.
347 * We do this by temporarily clearing all FS-related capabilities and
348 * switching the fsuid/fsgid around to the real ones.
349 */
350static const struct cred *access_override_creds(void)
351{
352 const struct cred *old_cred;
353 struct cred *override_cred;
354
355 override_cred = prepare_creds();
356 if (!override_cred)
357 return NULL;
358
359 override_cred->fsuid = override_cred->uid;
360 override_cred->fsgid = override_cred->gid;
361
362 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
363 /* Clear the capabilities if we switch to a non-root user */
364 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
365 if (!uid_eq(override_cred->uid, root_uid))
366 cap_clear(override_cred->cap_effective);
367 else
368 override_cred->cap_effective =
369 override_cred->cap_permitted;
370 }
371
372 /*
373 * The new set of credentials can *only* be used in
374 * task-synchronous circumstances, and does not need
375 * RCU freeing, unless somebody then takes a separate
376 * reference to it.
377 *
378 * NOTE! This is _only_ true because this credential
379 * is used purely for override_creds() that installs
380 * it as the subjective cred. Other threads will be
381 * accessing ->real_cred, not the subjective cred.
382 *
383 * If somebody _does_ make a copy of this (using the
384 * 'get_current_cred()' function), that will clear the
385 * non_rcu field, because now that other user may be
386 * expecting RCU freeing. But normal thread-synchronous
387 * cred accesses will keep things non-RCY.
388 */
389 override_cred->non_rcu = 1;
390
391 old_cred = override_creds(override_cred);
392
393 /* override_cred() gets its own ref */
394 put_cred(override_cred);
395
396 return old_cred;
397}
398
399static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
400{
401 struct path path;
402 struct inode *inode;
403 int res;
404 unsigned int lookup_flags = LOOKUP_FOLLOW;
405 const struct cred *old_cred = NULL;
406
407 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
408 return -EINVAL;
409
410 if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
411 return -EINVAL;
412
413 if (flags & AT_SYMLINK_NOFOLLOW)
414 lookup_flags &= ~LOOKUP_FOLLOW;
415 if (flags & AT_EMPTY_PATH)
416 lookup_flags |= LOOKUP_EMPTY;
417
418 if (!(flags & AT_EACCESS)) {
419 old_cred = access_override_creds();
420 if (!old_cred)
421 return -ENOMEM;
422 }
423
424retry:
425 res = user_path_at(dfd, filename, lookup_flags, &path);
426 if (res)
427 goto out;
428
429 inode = d_backing_inode(path.dentry);
430
431 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
432 /*
433 * MAY_EXEC on regular files is denied if the fs is mounted
434 * with the "noexec" flag.
435 */
436 res = -EACCES;
437 if (path_noexec(&path))
438 goto out_path_release;
439 }
440
441 res = inode_permission(mnt_user_ns(path.mnt), inode, mode | MAY_ACCESS);
442 /* SuS v2 requires we report a read only fs too */
443 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
444 goto out_path_release;
445 /*
446 * This is a rare case where using __mnt_is_readonly()
447 * is OK without a mnt_want/drop_write() pair. Since
448 * no actual write to the fs is performed here, we do
449 * not need to telegraph to that to anyone.
450 *
451 * By doing this, we accept that this access is
452 * inherently racy and know that the fs may change
453 * state before we even see this result.
454 */
455 if (__mnt_is_readonly(path.mnt))
456 res = -EROFS;
457
458out_path_release:
459 path_put(&path);
460 if (retry_estale(res, lookup_flags)) {
461 lookup_flags |= LOOKUP_REVAL;
462 goto retry;
463 }
464out:
465 if (old_cred)
466 revert_creds(old_cred);
467
468 return res;
469}
470
471SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
472{
473 return do_faccessat(dfd, filename, mode, 0);
474}
475
476SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
477 int, flags)
478{
479 return do_faccessat(dfd, filename, mode, flags);
480}
481
482SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
483{
484 return do_faccessat(AT_FDCWD, filename, mode, 0);
485}
486
487SYSCALL_DEFINE1(chdir, const char __user *, filename)
488{
489 struct path path;
490 int error;
491 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
492retry:
493 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
494 if (error)
495 goto out;
496
497 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
498 if (error)
499 goto dput_and_out;
500
501 set_fs_pwd(current->fs, &path);
502
503dput_and_out:
504 path_put(&path);
505 if (retry_estale(error, lookup_flags)) {
506 lookup_flags |= LOOKUP_REVAL;
507 goto retry;
508 }
509out:
510 return error;
511}
512
513SYSCALL_DEFINE1(fchdir, unsigned int, fd)
514{
515 struct fd f = fdget_raw(fd);
516 int error;
517
518 error = -EBADF;
519 if (!f.file)
520 goto out;
521
522 error = -ENOTDIR;
523 if (!d_can_lookup(f.file->f_path.dentry))
524 goto out_putf;
525
526 error = file_permission(f.file, MAY_EXEC | MAY_CHDIR);
527 if (!error)
528 set_fs_pwd(current->fs, &f.file->f_path);
529out_putf:
530 fdput(f);
531out:
532 return error;
533}
534
535SYSCALL_DEFINE1(chroot, const char __user *, filename)
536{
537 struct path path;
538 int error;
539 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
540retry:
541 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
542 if (error)
543 goto out;
544
545 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
546 if (error)
547 goto dput_and_out;
548
549 error = -EPERM;
550 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
551 goto dput_and_out;
552 error = security_path_chroot(&path);
553 if (error)
554 goto dput_and_out;
555
556 set_fs_root(current->fs, &path);
557 error = 0;
558dput_and_out:
559 path_put(&path);
560 if (retry_estale(error, lookup_flags)) {
561 lookup_flags |= LOOKUP_REVAL;
562 goto retry;
563 }
564out:
565 return error;
566}
567
568int chmod_common(const struct path *path, umode_t mode)
569{
570 struct inode *inode = path->dentry->d_inode;
571 struct inode *delegated_inode = NULL;
572 struct iattr newattrs;
573 int error;
574
575 error = mnt_want_write(path->mnt);
576 if (error)
577 return error;
578retry_deleg:
579 inode_lock(inode);
580 error = security_path_chmod(path, mode);
581 if (error)
582 goto out_unlock;
583 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
584 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
585 error = notify_change(mnt_user_ns(path->mnt), path->dentry,
586 &newattrs, &delegated_inode);
587out_unlock:
588 inode_unlock(inode);
589 if (delegated_inode) {
590 error = break_deleg_wait(&delegated_inode);
591 if (!error)
592 goto retry_deleg;
593 }
594 mnt_drop_write(path->mnt);
595 return error;
596}
597
598int vfs_fchmod(struct file *file, umode_t mode)
599{
600 audit_file(file);
601 return chmod_common(&file->f_path, mode);
602}
603
604SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
605{
606 struct fd f = fdget(fd);
607 int err = -EBADF;
608
609 if (f.file) {
610 err = vfs_fchmod(f.file, mode);
611 fdput(f);
612 }
613 return err;
614}
615
616static int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
617{
618 struct path path;
619 int error;
620 unsigned int lookup_flags = LOOKUP_FOLLOW;
621retry:
622 error = user_path_at(dfd, filename, lookup_flags, &path);
623 if (!error) {
624 error = chmod_common(&path, mode);
625 path_put(&path);
626 if (retry_estale(error, lookup_flags)) {
627 lookup_flags |= LOOKUP_REVAL;
628 goto retry;
629 }
630 }
631 return error;
632}
633
634SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
635 umode_t, mode)
636{
637 return do_fchmodat(dfd, filename, mode);
638}
639
640SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
641{
642 return do_fchmodat(AT_FDCWD, filename, mode);
643}
644
645int chown_common(const struct path *path, uid_t user, gid_t group)
646{
647 struct user_namespace *mnt_userns;
648 struct inode *inode = path->dentry->d_inode;
649 struct inode *delegated_inode = NULL;
650 int error;
651 struct iattr newattrs;
652 kuid_t uid;
653 kgid_t gid;
654
655 uid = make_kuid(current_user_ns(), user);
656 gid = make_kgid(current_user_ns(), group);
657
658 mnt_userns = mnt_user_ns(path->mnt);
659 uid = kuid_from_mnt(mnt_userns, uid);
660 gid = kgid_from_mnt(mnt_userns, gid);
661
662retry_deleg:
663 newattrs.ia_valid = ATTR_CTIME;
664 if (user != (uid_t) -1) {
665 if (!uid_valid(uid))
666 return -EINVAL;
667 newattrs.ia_valid |= ATTR_UID;
668 newattrs.ia_uid = uid;
669 }
670 if (group != (gid_t) -1) {
671 if (!gid_valid(gid))
672 return -EINVAL;
673 newattrs.ia_valid |= ATTR_GID;
674 newattrs.ia_gid = gid;
675 }
676 if (!S_ISDIR(inode->i_mode))
677 newattrs.ia_valid |=
678 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
679 inode_lock(inode);
680 error = security_path_chown(path, uid, gid);
681 if (!error)
682 error = notify_change(mnt_userns, path->dentry, &newattrs,
683 &delegated_inode);
684 inode_unlock(inode);
685 if (delegated_inode) {
686 error = break_deleg_wait(&delegated_inode);
687 if (!error)
688 goto retry_deleg;
689 }
690 return error;
691}
692
693int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
694 int flag)
695{
696 struct path path;
697 int error = -EINVAL;
698 int lookup_flags;
699
700 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
701 goto out;
702
703 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
704 if (flag & AT_EMPTY_PATH)
705 lookup_flags |= LOOKUP_EMPTY;
706retry:
707 error = user_path_at(dfd, filename, lookup_flags, &path);
708 if (error)
709 goto out;
710 error = mnt_want_write(path.mnt);
711 if (error)
712 goto out_release;
713 error = chown_common(&path, user, group);
714 mnt_drop_write(path.mnt);
715out_release:
716 path_put(&path);
717 if (retry_estale(error, lookup_flags)) {
718 lookup_flags |= LOOKUP_REVAL;
719 goto retry;
720 }
721out:
722 return error;
723}
724
725SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
726 gid_t, group, int, flag)
727{
728 return do_fchownat(dfd, filename, user, group, flag);
729}
730
731SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
732{
733 return do_fchownat(AT_FDCWD, filename, user, group, 0);
734}
735
736SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
737{
738 return do_fchownat(AT_FDCWD, filename, user, group,
739 AT_SYMLINK_NOFOLLOW);
740}
741
742int vfs_fchown(struct file *file, uid_t user, gid_t group)
743{
744 int error;
745
746 error = mnt_want_write_file(file);
747 if (error)
748 return error;
749 audit_file(file);
750 error = chown_common(&file->f_path, user, group);
751 mnt_drop_write_file(file);
752 return error;
753}
754
755int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
756{
757 struct fd f = fdget(fd);
758 int error = -EBADF;
759
760 if (f.file) {
761 error = vfs_fchown(f.file, user, group);
762 fdput(f);
763 }
764 return error;
765}
766
767SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
768{
769 return ksys_fchown(fd, user, group);
770}
771
772static int do_dentry_open(struct file *f,
773 struct inode *inode,
774 int (*open)(struct inode *, struct file *))
775{
776 static const struct file_operations empty_fops = {};
777 int error;
778
779 path_get(&f->f_path);
780 f->f_inode = inode;
781 f->f_mapping = inode->i_mapping;
782 f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
783 f->f_sb_err = file_sample_sb_err(f);
784
785 if (unlikely(f->f_flags & O_PATH)) {
786 f->f_mode = FMODE_PATH | FMODE_OPENED;
787 f->f_op = &empty_fops;
788 return 0;
789 }
790
791 if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
792 error = get_write_access(inode);
793 if (unlikely(error))
794 goto cleanup_file;
795 error = __mnt_want_write(f->f_path.mnt);
796 if (unlikely(error)) {
797 put_write_access(inode);
798 goto cleanup_file;
799 }
800 f->f_mode |= FMODE_WRITER;
801 }
802
803 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
804 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
805 f->f_mode |= FMODE_ATOMIC_POS;
806
807 f->f_op = fops_get(inode->i_fop);
808 if (WARN_ON(!f->f_op)) {
809 error = -ENODEV;
810 goto cleanup_all;
811 }
812
813 error = security_file_open(f);
814 if (error)
815 goto cleanup_all;
816
817 error = break_lease(locks_inode(f), f->f_flags);
818 if (error)
819 goto cleanup_all;
820
821 /* normally all 3 are set; ->open() can clear them if needed */
822 f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
823 if (!open)
824 open = f->f_op->open;
825 if (open) {
826 error = open(inode, f);
827 if (error)
828 goto cleanup_all;
829 }
830 f->f_mode |= FMODE_OPENED;
831 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
832 i_readcount_inc(inode);
833 if ((f->f_mode & FMODE_READ) &&
834 likely(f->f_op->read || f->f_op->read_iter))
835 f->f_mode |= FMODE_CAN_READ;
836 if ((f->f_mode & FMODE_WRITE) &&
837 likely(f->f_op->write || f->f_op->write_iter))
838 f->f_mode |= FMODE_CAN_WRITE;
839
840 f->f_write_hint = WRITE_LIFE_NOT_SET;
841 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
842
843 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
844
845 /* NB: we're sure to have correct a_ops only after f_op->open */
846 if (f->f_flags & O_DIRECT) {
847 if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
848 return -EINVAL;
849 }
850
851 /*
852 * XXX: Huge page cache doesn't support writing yet. Drop all page
853 * cache for this file before processing writes.
854 */
855 if (f->f_mode & FMODE_WRITE) {
856 /*
857 * Paired with smp_mb() in collapse_file() to ensure nr_thps
858 * is up to date and the update to i_writecount by
859 * get_write_access() is visible. Ensures subsequent insertion
860 * of THPs into the page cache will fail.
861 */
862 smp_mb();
863 if (filemap_nr_thps(inode->i_mapping))
864 truncate_pagecache(inode, 0);
865 }
866
867 return 0;
868
869cleanup_all:
870 if (WARN_ON_ONCE(error > 0))
871 error = -EINVAL;
872 fops_put(f->f_op);
873 if (f->f_mode & FMODE_WRITER) {
874 put_write_access(inode);
875 __mnt_drop_write(f->f_path.mnt);
876 }
877cleanup_file:
878 path_put(&f->f_path);
879 f->f_path.mnt = NULL;
880 f->f_path.dentry = NULL;
881 f->f_inode = NULL;
882 return error;
883}
884
885/**
886 * finish_open - finish opening a file
887 * @file: file pointer
888 * @dentry: pointer to dentry
889 * @open: open callback
890 * @opened: state of open
891 *
892 * This can be used to finish opening a file passed to i_op->atomic_open().
893 *
894 * If the open callback is set to NULL, then the standard f_op->open()
895 * filesystem callback is substituted.
896 *
897 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
898 * the return value of d_splice_alias(), then the caller needs to perform dput()
899 * on it after finish_open().
900 *
901 * Returns zero on success or -errno if the open failed.
902 */
903int finish_open(struct file *file, struct dentry *dentry,
904 int (*open)(struct inode *, struct file *))
905{
906 BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
907
908 file->f_path.dentry = dentry;
909 return do_dentry_open(file, d_backing_inode(dentry), open);
910}
911EXPORT_SYMBOL(finish_open);
912
913/**
914 * finish_no_open - finish ->atomic_open() without opening the file
915 *
916 * @file: file pointer
917 * @dentry: dentry or NULL (as returned from ->lookup())
918 *
919 * This can be used to set the result of a successful lookup in ->atomic_open().
920 *
921 * NB: unlike finish_open() this function does consume the dentry reference and
922 * the caller need not dput() it.
923 *
924 * Returns "0" which must be the return value of ->atomic_open() after having
925 * called this function.
926 */
927int finish_no_open(struct file *file, struct dentry *dentry)
928{
929 file->f_path.dentry = dentry;
930 return 0;
931}
932EXPORT_SYMBOL(finish_no_open);
933
934char *file_path(struct file *filp, char *buf, int buflen)
935{
936 return d_path(&filp->f_path, buf, buflen);
937}
938EXPORT_SYMBOL(file_path);
939
940/**
941 * vfs_open - open the file at the given path
942 * @path: path to open
943 * @file: newly allocated file with f_flag initialized
944 * @cred: credentials to use
945 */
946int vfs_open(const struct path *path, struct file *file)
947{
948 file->f_path = *path;
949 return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
950}
951
952struct file *dentry_open(const struct path *path, int flags,
953 const struct cred *cred)
954{
955 int error;
956 struct file *f;
957
958 validate_creds(cred);
959
960 /* We must always pass in a valid mount pointer. */
961 BUG_ON(!path->mnt);
962
963 f = alloc_empty_file(flags, cred);
964 if (!IS_ERR(f)) {
965 error = vfs_open(path, f);
966 if (error) {
967 fput(f);
968 f = ERR_PTR(error);
969 }
970 }
971 return f;
972}
973EXPORT_SYMBOL(dentry_open);
974
975struct file *open_with_fake_path(const struct path *path, int flags,
976 struct inode *inode, const struct cred *cred)
977{
978 struct file *f = alloc_empty_file_noaccount(flags, cred);
979 if (!IS_ERR(f)) {
980 int error;
981
982 f->f_path = *path;
983 error = do_dentry_open(f, inode, NULL);
984 if (error) {
985 fput(f);
986 f = ERR_PTR(error);
987 }
988 }
989 return f;
990}
991EXPORT_SYMBOL(open_with_fake_path);
992
993#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE))
994#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
995
996inline struct open_how build_open_how(int flags, umode_t mode)
997{
998 struct open_how how = {
999 .flags = flags & VALID_OPEN_FLAGS,
1000 .mode = mode & S_IALLUGO,
1001 };
1002
1003 /* O_PATH beats everything else. */
1004 if (how.flags & O_PATH)
1005 how.flags &= O_PATH_FLAGS;
1006 /* Modes should only be set for create-like flags. */
1007 if (!WILL_CREATE(how.flags))
1008 how.mode = 0;
1009 return how;
1010}
1011
1012inline int build_open_flags(const struct open_how *how, struct open_flags *op)
1013{
1014 u64 flags = how->flags;
1015 u64 strip = FMODE_NONOTIFY | O_CLOEXEC;
1016 int lookup_flags = 0;
1017 int acc_mode = ACC_MODE(flags);
1018
1019 BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
1020 "struct open_flags doesn't yet handle flags > 32 bits");
1021
1022 /*
1023 * Strip flags that either shouldn't be set by userspace like
1024 * FMODE_NONOTIFY or that aren't relevant in determining struct
1025 * open_flags like O_CLOEXEC.
1026 */
1027 flags &= ~strip;
1028
1029 /*
1030 * Older syscalls implicitly clear all of the invalid flags or argument
1031 * values before calling build_open_flags(), but openat2(2) checks all
1032 * of its arguments.
1033 */
1034 if (flags & ~VALID_OPEN_FLAGS)
1035 return -EINVAL;
1036 if (how->resolve & ~VALID_RESOLVE_FLAGS)
1037 return -EINVAL;
1038
1039 /* Scoping flags are mutually exclusive. */
1040 if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
1041 return -EINVAL;
1042
1043 /* Deal with the mode. */
1044 if (WILL_CREATE(flags)) {
1045 if (how->mode & ~S_IALLUGO)
1046 return -EINVAL;
1047 op->mode = how->mode | S_IFREG;
1048 } else {
1049 if (how->mode != 0)
1050 return -EINVAL;
1051 op->mode = 0;
1052 }
1053
1054 /*
1055 * In order to ensure programs get explicit errors when trying to use
1056 * O_TMPFILE on old kernels, O_TMPFILE is implemented such that it
1057 * looks like (O_DIRECTORY|O_RDWR & ~O_CREAT) to old kernels. But we
1058 * have to require userspace to explicitly set it.
1059 */
1060 if (flags & __O_TMPFILE) {
1061 if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
1062 return -EINVAL;
1063 if (!(acc_mode & MAY_WRITE))
1064 return -EINVAL;
1065 }
1066 if (flags & O_PATH) {
1067 /* O_PATH only permits certain other flags to be set. */
1068 if (flags & ~O_PATH_FLAGS)
1069 return -EINVAL;
1070 acc_mode = 0;
1071 }
1072
1073 /*
1074 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1075 * check for O_DSYNC if the need any syncing at all we enforce it's
1076 * always set instead of having to deal with possibly weird behaviour
1077 * for malicious applications setting only __O_SYNC.
1078 */
1079 if (flags & __O_SYNC)
1080 flags |= O_DSYNC;
1081
1082 op->open_flag = flags;
1083
1084 /* O_TRUNC implies we need access checks for write permissions */
1085 if (flags & O_TRUNC)
1086 acc_mode |= MAY_WRITE;
1087
1088 /* Allow the LSM permission hook to distinguish append
1089 access from general write access. */
1090 if (flags & O_APPEND)
1091 acc_mode |= MAY_APPEND;
1092
1093 op->acc_mode = acc_mode;
1094
1095 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1096
1097 if (flags & O_CREAT) {
1098 op->intent |= LOOKUP_CREATE;
1099 if (flags & O_EXCL) {
1100 op->intent |= LOOKUP_EXCL;
1101 flags |= O_NOFOLLOW;
1102 }
1103 }
1104
1105 if (flags & O_DIRECTORY)
1106 lookup_flags |= LOOKUP_DIRECTORY;
1107 if (!(flags & O_NOFOLLOW))
1108 lookup_flags |= LOOKUP_FOLLOW;
1109
1110 if (how->resolve & RESOLVE_NO_XDEV)
1111 lookup_flags |= LOOKUP_NO_XDEV;
1112 if (how->resolve & RESOLVE_NO_MAGICLINKS)
1113 lookup_flags |= LOOKUP_NO_MAGICLINKS;
1114 if (how->resolve & RESOLVE_NO_SYMLINKS)
1115 lookup_flags |= LOOKUP_NO_SYMLINKS;
1116 if (how->resolve & RESOLVE_BENEATH)
1117 lookup_flags |= LOOKUP_BENEATH;
1118 if (how->resolve & RESOLVE_IN_ROOT)
1119 lookup_flags |= LOOKUP_IN_ROOT;
1120 if (how->resolve & RESOLVE_CACHED) {
1121 /* Don't bother even trying for create/truncate/tmpfile open */
1122 if (flags & (O_TRUNC | O_CREAT | O_TMPFILE))
1123 return -EAGAIN;
1124 lookup_flags |= LOOKUP_CACHED;
1125 }
1126
1127 op->lookup_flags = lookup_flags;
1128 return 0;
1129}
1130
1131/**
1132 * file_open_name - open file and return file pointer
1133 *
1134 * @name: struct filename containing path to open
1135 * @flags: open flags as per the open(2) second argument
1136 * @mode: mode for the new file if O_CREAT is set, else ignored
1137 *
1138 * This is the helper to open a file from kernelspace if you really
1139 * have to. But in generally you should not do this, so please move
1140 * along, nothing to see here..
1141 */
1142struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1143{
1144 struct open_flags op;
1145 struct open_how how = build_open_how(flags, mode);
1146 int err = build_open_flags(&how, &op);
1147 if (err)
1148 return ERR_PTR(err);
1149 return do_filp_open(AT_FDCWD, name, &op);
1150}
1151
1152/**
1153 * filp_open - open file and return file pointer
1154 *
1155 * @filename: path to open
1156 * @flags: open flags as per the open(2) second argument
1157 * @mode: mode for the new file if O_CREAT is set, else ignored
1158 *
1159 * This is the helper to open a file from kernelspace if you really
1160 * have to. But in generally you should not do this, so please move
1161 * along, nothing to see here..
1162 */
1163struct file *filp_open(const char *filename, int flags, umode_t mode)
1164{
1165 struct filename *name = getname_kernel(filename);
1166 struct file *file = ERR_CAST(name);
1167
1168 if (!IS_ERR(name)) {
1169 file = file_open_name(name, flags, mode);
1170 putname(name);
1171 }
1172 return file;
1173}
1174EXPORT_SYMBOL(filp_open);
1175
1176struct file *file_open_root(const struct path *root,
1177 const char *filename, int flags, umode_t mode)
1178{
1179 struct open_flags op;
1180 struct open_how how = build_open_how(flags, mode);
1181 int err = build_open_flags(&how, &op);
1182 if (err)
1183 return ERR_PTR(err);
1184 return do_file_open_root(root, filename, &op);
1185}
1186EXPORT_SYMBOL(file_open_root);
1187
1188static long do_sys_openat2(int dfd, const char __user *filename,
1189 struct open_how *how)
1190{
1191 struct open_flags op;
1192 int fd = build_open_flags(how, &op);
1193 struct filename *tmp;
1194
1195 if (fd)
1196 return fd;
1197
1198 tmp = getname(filename);
1199 if (IS_ERR(tmp))
1200 return PTR_ERR(tmp);
1201
1202 fd = get_unused_fd_flags(how->flags);
1203 if (fd >= 0) {
1204 struct file *f = do_filp_open(dfd, tmp, &op);
1205 if (IS_ERR(f)) {
1206 put_unused_fd(fd);
1207 fd = PTR_ERR(f);
1208 } else {
1209 fsnotify_open(f);
1210 fd_install(fd, f);
1211 }
1212 }
1213 putname(tmp);
1214 return fd;
1215}
1216
1217long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1218{
1219 struct open_how how = build_open_how(flags, mode);
1220 return do_sys_openat2(dfd, filename, &how);
1221}
1222
1223
1224SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1225{
1226 if (force_o_largefile())
1227 flags |= O_LARGEFILE;
1228 return do_sys_open(AT_FDCWD, filename, flags, mode);
1229}
1230
1231SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1232 umode_t, mode)
1233{
1234 if (force_o_largefile())
1235 flags |= O_LARGEFILE;
1236 return do_sys_open(dfd, filename, flags, mode);
1237}
1238
1239SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1240 struct open_how __user *, how, size_t, usize)
1241{
1242 int err;
1243 struct open_how tmp;
1244
1245 BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1246 BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1247
1248 if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1249 return -EINVAL;
1250
1251 err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
1252 if (err)
1253 return err;
1254
1255 /* O_LARGEFILE is only allowed for non-O_PATH. */
1256 if (!(tmp.flags & O_PATH) && force_o_largefile())
1257 tmp.flags |= O_LARGEFILE;
1258
1259 return do_sys_openat2(dfd, filename, &tmp);
1260}
1261
1262#ifdef CONFIG_COMPAT
1263/*
1264 * Exactly like sys_open(), except that it doesn't set the
1265 * O_LARGEFILE flag.
1266 */
1267COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1268{
1269 return do_sys_open(AT_FDCWD, filename, flags, mode);
1270}
1271
1272/*
1273 * Exactly like sys_openat(), except that it doesn't set the
1274 * O_LARGEFILE flag.
1275 */
1276COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1277{
1278 return do_sys_open(dfd, filename, flags, mode);
1279}
1280#endif
1281
1282#ifndef __alpha__
1283
1284/*
1285 * For backward compatibility? Maybe this should be moved
1286 * into arch/i386 instead?
1287 */
1288SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1289{
1290 int flags = O_CREAT | O_WRONLY | O_TRUNC;
1291
1292 if (force_o_largefile())
1293 flags |= O_LARGEFILE;
1294 return do_sys_open(AT_FDCWD, pathname, flags, mode);
1295}
1296#endif
1297
1298/*
1299 * "id" is the POSIX thread ID. We use the
1300 * files pointer for this..
1301 */
1302int filp_close(struct file *filp, fl_owner_t id)
1303{
1304 int retval = 0;
1305
1306 if (!file_count(filp)) {
1307 printk(KERN_ERR "VFS: Close: file count is 0\n");
1308 return 0;
1309 }
1310
1311 if (filp->f_op->flush)
1312 retval = filp->f_op->flush(filp, id);
1313
1314 if (likely(!(filp->f_mode & FMODE_PATH))) {
1315 dnotify_flush(filp, id);
1316 locks_remove_posix(filp, id);
1317 }
1318 fput(filp);
1319 return retval;
1320}
1321
1322EXPORT_SYMBOL(filp_close);
1323
1324/*
1325 * Careful here! We test whether the file pointer is NULL before
1326 * releasing the fd. This ensures that one clone task can't release
1327 * an fd while another clone is opening it.
1328 */
1329SYSCALL_DEFINE1(close, unsigned int, fd)
1330{
1331 int retval = close_fd(fd);
1332
1333 /* can't restart close syscall because file table entry was cleared */
1334 if (unlikely(retval == -ERESTARTSYS ||
1335 retval == -ERESTARTNOINTR ||
1336 retval == -ERESTARTNOHAND ||
1337 retval == -ERESTART_RESTARTBLOCK))
1338 retval = -EINTR;
1339
1340 return retval;
1341}
1342
1343/**
1344 * close_range() - Close all file descriptors in a given range.
1345 *
1346 * @fd: starting file descriptor to close
1347 * @max_fd: last file descriptor to close
1348 * @flags: reserved for future extensions
1349 *
1350 * This closes a range of file descriptors. All file descriptors
1351 * from @fd up to and including @max_fd are closed.
1352 * Currently, errors to close a given file descriptor are ignored.
1353 */
1354SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
1355 unsigned int, flags)
1356{
1357 return __close_range(fd, max_fd, flags);
1358}
1359
1360/*
1361 * This routine simulates a hangup on the tty, to arrange that users
1362 * are given clean terminals at login time.
1363 */
1364SYSCALL_DEFINE0(vhangup)
1365{
1366 if (capable(CAP_SYS_TTY_CONFIG)) {
1367 tty_vhangup_self();
1368 return 0;
1369 }
1370 return -EPERM;
1371}
1372
1373/*
1374 * Called when an inode is about to be open.
1375 * We use this to disallow opening large files on 32bit systems if
1376 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1377 * on this flag in sys_open.
1378 */
1379int generic_file_open(struct inode * inode, struct file * filp)
1380{
1381 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1382 return -EOVERFLOW;
1383 return 0;
1384}
1385
1386EXPORT_SYMBOL(generic_file_open);
1387
1388/*
1389 * This is used by subsystems that don't want seekable
1390 * file descriptors. The function is not supposed to ever fail, the only
1391 * reason it returns an 'int' and not 'void' is so that it can be plugged
1392 * directly into file_operations structure.
1393 */
1394int nonseekable_open(struct inode *inode, struct file *filp)
1395{
1396 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1397 return 0;
1398}
1399
1400EXPORT_SYMBOL(nonseekable_open);
1401
1402/*
1403 * stream_open is used by subsystems that want stream-like file descriptors.
1404 * Such file descriptors are not seekable and don't have notion of position
1405 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1406 * Contrary to file descriptors of other regular files, .read() and .write()
1407 * can run simultaneously.
1408 *
1409 * stream_open never fails and is marked to return int so that it could be
1410 * directly used as file_operations.open .
1411 */
1412int stream_open(struct inode *inode, struct file *filp)
1413{
1414 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1415 filp->f_mode |= FMODE_STREAM;
1416 return 0;
1417}
1418
1419EXPORT_SYMBOL(stream_open);