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
39 int 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
70 long 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
113 put_write_and_out:
114 put_write_access(inode);
115 mnt_drop_write_and_out:
116 mnt_drop_write(path->mnt);
117 out:
118 return error;
119 }
120 EXPORT_SYMBOL_GPL(vfs_truncate);
121
122 long 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
131 retry:
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
144 SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
145 {
146 return do_sys_truncate(path, length);
147 }
148
149 #ifdef CONFIG_COMPAT
150 COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
151 {
152 return do_sys_truncate(path, length);
153 }
154 #endif
155
156 long 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
188 long 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
205 SYSCALL_DEFINE2(ftruncate, unsigned int, fd, off_t, length)
206 {
207 return do_sys_ftruncate(fd, length, 1);
208 }
209
210 #ifdef CONFIG_COMPAT
211 COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_off_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
219 SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
220 {
221 return do_sys_truncate(path, length);
222 }
223
224 SYSCALL_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)
231 COMPAT_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)
239 COMPAT_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
246 int 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 loff_t sum;
251
252 if (offset < 0 || len <= 0)
253 return -EINVAL;
254
255 /* Return error if mode is not supported */
256 if (mode & ~FALLOC_FL_SUPPORTED_MASK)
257 return -EOPNOTSUPP;
258
259 /* Punch hole and zero range are mutually exclusive */
260 if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
261 (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
262 return -EOPNOTSUPP;
263
264 /* Punch hole must have keep size set */
265 if ((mode & FALLOC_FL_PUNCH_HOLE) &&
266 !(mode & FALLOC_FL_KEEP_SIZE))
267 return -EOPNOTSUPP;
268
269 /* Collapse range should only be used exclusively. */
270 if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
271 (mode & ~FALLOC_FL_COLLAPSE_RANGE))
272 return -EINVAL;
273
274 /* Insert range should only be used exclusively. */
275 if ((mode & FALLOC_FL_INSERT_RANGE) &&
276 (mode & ~FALLOC_FL_INSERT_RANGE))
277 return -EINVAL;
278
279 /* Unshare range should only be used with allocate mode. */
280 if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
281 (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
282 return -EINVAL;
283
284 if (!(file->f_mode & FMODE_WRITE))
285 return -EBADF;
286
287 /*
288 * We can only allow pure fallocate on append only files
289 */
290 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
291 return -EPERM;
292
293 if (IS_IMMUTABLE(inode))
294 return -EPERM;
295
296 /*
297 * We cannot allow any fallocate operation on an active swapfile
298 */
299 if (IS_SWAPFILE(inode))
300 return -ETXTBSY;
301
302 /*
303 * Revalidate the write permissions, in case security policy has
304 * changed since the files were opened.
305 */
306 ret = security_file_permission(file, MAY_WRITE);
307 if (ret)
308 return ret;
309
310 ret = fsnotify_file_area_perm(file, MAY_WRITE, &offset, len);
311 if (ret)
312 return ret;
313
314 if (S_ISFIFO(inode->i_mode))
315 return -ESPIPE;
316
317 if (S_ISDIR(inode->i_mode))
318 return -EISDIR;
319
320 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
321 return -ENODEV;
322
323 /* Check for wraparound */
324 if (check_add_overflow(offset, len, &sum))
325 return -EFBIG;
326
327 if (sum > inode->i_sb->s_maxbytes)
328 return -EFBIG;
329
330 if (!file->f_op->fallocate)
331 return -EOPNOTSUPP;
332
333 file_start_write(file);
334 ret = file->f_op->fallocate(file, mode, offset, len);
335
336 /*
337 * Create inotify and fanotify events.
338 *
339 * To keep the logic simple always create events if fallocate succeeds.
340 * This implies that events are even created if the file size remains
341 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
342 */
343 if (ret == 0)
344 fsnotify_modify(file);
345
346 file_end_write(file);
347 return ret;
348 }
349 EXPORT_SYMBOL_GPL(vfs_fallocate);
350
351 int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
352 {
353 struct fd f = fdget(fd);
354 int error = -EBADF;
355
356 if (f.file) {
357 error = vfs_fallocate(f.file, mode, offset, len);
358 fdput(f);
359 }
360 return error;
361 }
362
363 SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
364 {
365 return ksys_fallocate(fd, mode, offset, len);
366 }
367
368 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE)
369 COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset),
370 compat_arg_u64_dual(len))
371 {
372 return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset),
373 compat_arg_u64_glue(len));
374 }
375 #endif
376
377 /*
378 * access() needs to use the real uid/gid, not the effective uid/gid.
379 * We do this by temporarily clearing all FS-related capabilities and
380 * switching the fsuid/fsgid around to the real ones.
381 *
382 * Creating new credentials is expensive, so we try to skip doing it,
383 * which we can if the result would match what we already got.
384 */
385 static bool access_need_override_creds(int flags)
386 {
387 const struct cred *cred;
388
389 if (flags & AT_EACCESS)
390 return false;
391
392 cred = current_cred();
393 if (!uid_eq(cred->fsuid, cred->uid) ||
394 !gid_eq(cred->fsgid, cred->gid))
395 return true;
396
397 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
398 kuid_t root_uid = make_kuid(cred->user_ns, 0);
399 if (!uid_eq(cred->uid, root_uid)) {
400 if (!cap_isclear(cred->cap_effective))
401 return true;
402 } else {
403 if (!cap_isidentical(cred->cap_effective,
404 cred->cap_permitted))
405 return true;
406 }
407 }
408
409 return false;
410 }
411
412 static const struct cred *access_override_creds(void)
413 {
414 const struct cred *old_cred;
415 struct cred *override_cred;
416
417 override_cred = prepare_creds();
418 if (!override_cred)
419 return NULL;
420
421 /*
422 * XXX access_need_override_creds performs checks in hopes of skipping
423 * this work. Make sure it stays in sync if making any changes in this
424 * routine.
425 */
426
427 override_cred->fsuid = override_cred->uid;
428 override_cred->fsgid = override_cred->gid;
429
430 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
431 /* Clear the capabilities if we switch to a non-root user */
432 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
433 if (!uid_eq(override_cred->uid, root_uid))
434 cap_clear(override_cred->cap_effective);
435 else
436 override_cred->cap_effective =
437 override_cred->cap_permitted;
438 }
439
440 /*
441 * The new set of credentials can *only* be used in
442 * task-synchronous circumstances, and does not need
443 * RCU freeing, unless somebody then takes a separate
444 * reference to it.
445 *
446 * NOTE! This is _only_ true because this credential
447 * is used purely for override_creds() that installs
448 * it as the subjective cred. Other threads will be
449 * accessing ->real_cred, not the subjective cred.
450 *
451 * If somebody _does_ make a copy of this (using the
452 * 'get_current_cred()' function), that will clear the
453 * non_rcu field, because now that other user may be
454 * expecting RCU freeing. But normal thread-synchronous
455 * cred accesses will keep things non-racy to avoid RCU
456 * freeing.
457 */
458 override_cred->non_rcu = 1;
459
460 old_cred = override_creds(override_cred);
461
462 /* override_cred() gets its own ref */
463 put_cred(override_cred);
464
465 return old_cred;
466 }
467
468 static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
469 {
470 struct path path;
471 struct inode *inode;
472 int res;
473 unsigned int lookup_flags = LOOKUP_FOLLOW;
474 const struct cred *old_cred = NULL;
475
476 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
477 return -EINVAL;
478
479 if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
480 return -EINVAL;
481
482 if (flags & AT_SYMLINK_NOFOLLOW)
483 lookup_flags &= ~LOOKUP_FOLLOW;
484 if (flags & AT_EMPTY_PATH)
485 lookup_flags |= LOOKUP_EMPTY;
486
487 if (access_need_override_creds(flags)) {
488 old_cred = access_override_creds();
489 if (!old_cred)
490 return -ENOMEM;
491 }
492
493 retry:
494 res = user_path_at(dfd, filename, lookup_flags, &path);
495 if (res)
496 goto out;
497
498 inode = d_backing_inode(path.dentry);
499
500 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
501 /*
502 * MAY_EXEC on regular files is denied if the fs is mounted
503 * with the "noexec" flag.
504 */
505 res = -EACCES;
506 if (path_noexec(&path))
507 goto out_path_release;
508 }
509
510 res = inode_permission(mnt_idmap(path.mnt), inode, mode | MAY_ACCESS);
511 /* SuS v2 requires we report a read only fs too */
512 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
513 goto out_path_release;
514 /*
515 * This is a rare case where using __mnt_is_readonly()
516 * is OK without a mnt_want/drop_write() pair. Since
517 * no actual write to the fs is performed here, we do
518 * not need to telegraph to that to anyone.
519 *
520 * By doing this, we accept that this access is
521 * inherently racy and know that the fs may change
522 * state before we even see this result.
523 */
524 if (__mnt_is_readonly(path.mnt))
525 res = -EROFS;
526
527 out_path_release:
528 path_put(&path);
529 if (retry_estale(res, lookup_flags)) {
530 lookup_flags |= LOOKUP_REVAL;
531 goto retry;
532 }
533 out:
534 if (old_cred)
535 revert_creds(old_cred);
536
537 return res;
538 }
539
540 SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
541 {
542 return do_faccessat(dfd, filename, mode, 0);
543 }
544
545 SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
546 int, flags)
547 {
548 return do_faccessat(dfd, filename, mode, flags);
549 }
550
551 SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
552 {
553 return do_faccessat(AT_FDCWD, filename, mode, 0);
554 }
555
556 SYSCALL_DEFINE1(chdir, const char __user *, filename)
557 {
558 struct path path;
559 int error;
560 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
561 retry:
562 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
563 if (error)
564 goto out;
565
566 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
567 if (error)
568 goto dput_and_out;
569
570 set_fs_pwd(current->fs, &path);
571
572 dput_and_out:
573 path_put(&path);
574 if (retry_estale(error, lookup_flags)) {
575 lookup_flags |= LOOKUP_REVAL;
576 goto retry;
577 }
578 out:
579 return error;
580 }
581
582 SYSCALL_DEFINE1(fchdir, unsigned int, fd)
583 {
584 struct fd f = fdget_raw(fd);
585 int error;
586
587 error = -EBADF;
588 if (!f.file)
589 goto out;
590
591 error = -ENOTDIR;
592 if (!d_can_lookup(f.file->f_path.dentry))
593 goto out_putf;
594
595 error = file_permission(f.file, MAY_EXEC | MAY_CHDIR);
596 if (!error)
597 set_fs_pwd(current->fs, &f.file->f_path);
598 out_putf:
599 fdput(f);
600 out:
601 return error;
602 }
603
604 SYSCALL_DEFINE1(chroot, const char __user *, filename)
605 {
606 struct path path;
607 int error;
608 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
609 retry:
610 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
611 if (error)
612 goto out;
613
614 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
615 if (error)
616 goto dput_and_out;
617
618 error = -EPERM;
619 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
620 goto dput_and_out;
621 error = security_path_chroot(&path);
622 if (error)
623 goto dput_and_out;
624
625 set_fs_root(current->fs, &path);
626 error = 0;
627 dput_and_out:
628 path_put(&path);
629 if (retry_estale(error, lookup_flags)) {
630 lookup_flags |= LOOKUP_REVAL;
631 goto retry;
632 }
633 out:
634 return error;
635 }
636
637 int chmod_common(const struct path *path, umode_t mode)
638 {
639 struct inode *inode = path->dentry->d_inode;
640 struct inode *delegated_inode = NULL;
641 struct iattr newattrs;
642 int error;
643
644 error = mnt_want_write(path->mnt);
645 if (error)
646 return error;
647 retry_deleg:
648 inode_lock(inode);
649 error = security_path_chmod(path, mode);
650 if (error)
651 goto out_unlock;
652 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
653 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
654 error = notify_change(mnt_idmap(path->mnt), path->dentry,
655 &newattrs, &delegated_inode);
656 out_unlock:
657 inode_unlock(inode);
658 if (delegated_inode) {
659 error = break_deleg_wait(&delegated_inode);
660 if (!error)
661 goto retry_deleg;
662 }
663 mnt_drop_write(path->mnt);
664 return error;
665 }
666
667 int vfs_fchmod(struct file *file, umode_t mode)
668 {
669 audit_file(file);
670 return chmod_common(&file->f_path, mode);
671 }
672
673 SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
674 {
675 struct fd f = fdget(fd);
676 int err = -EBADF;
677
678 if (f.file) {
679 err = vfs_fchmod(f.file, mode);
680 fdput(f);
681 }
682 return err;
683 }
684
685 static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
686 unsigned int flags)
687 {
688 struct path path;
689 int error;
690 unsigned int lookup_flags;
691
692 if (unlikely(flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)))
693 return -EINVAL;
694
695 lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
696 if (flags & AT_EMPTY_PATH)
697 lookup_flags |= LOOKUP_EMPTY;
698
699 retry:
700 error = user_path_at(dfd, filename, lookup_flags, &path);
701 if (!error) {
702 error = chmod_common(&path, mode);
703 path_put(&path);
704 if (retry_estale(error, lookup_flags)) {
705 lookup_flags |= LOOKUP_REVAL;
706 goto retry;
707 }
708 }
709 return error;
710 }
711
712 SYSCALL_DEFINE4(fchmodat2, int, dfd, const char __user *, filename,
713 umode_t, mode, unsigned int, flags)
714 {
715 return do_fchmodat(dfd, filename, mode, flags);
716 }
717
718 SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
719 umode_t, mode)
720 {
721 return do_fchmodat(dfd, filename, mode, 0);
722 }
723
724 SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
725 {
726 return do_fchmodat(AT_FDCWD, filename, mode, 0);
727 }
728
729 /*
730 * Check whether @kuid is valid and if so generate and set vfsuid_t in
731 * ia_vfsuid.
732 *
733 * Return: true if @kuid is valid, false if not.
734 */
735 static inline bool setattr_vfsuid(struct iattr *attr, kuid_t kuid)
736 {
737 if (!uid_valid(kuid))
738 return false;
739 attr->ia_valid |= ATTR_UID;
740 attr->ia_vfsuid = VFSUIDT_INIT(kuid);
741 return true;
742 }
743
744 /*
745 * Check whether @kgid is valid and if so generate and set vfsgid_t in
746 * ia_vfsgid.
747 *
748 * Return: true if @kgid is valid, false if not.
749 */
750 static inline bool setattr_vfsgid(struct iattr *attr, kgid_t kgid)
751 {
752 if (!gid_valid(kgid))
753 return false;
754 attr->ia_valid |= ATTR_GID;
755 attr->ia_vfsgid = VFSGIDT_INIT(kgid);
756 return true;
757 }
758
759 int chown_common(const struct path *path, uid_t user, gid_t group)
760 {
761 struct mnt_idmap *idmap;
762 struct user_namespace *fs_userns;
763 struct inode *inode = path->dentry->d_inode;
764 struct inode *delegated_inode = NULL;
765 int error;
766 struct iattr newattrs;
767 kuid_t uid;
768 kgid_t gid;
769
770 uid = make_kuid(current_user_ns(), user);
771 gid = make_kgid(current_user_ns(), group);
772
773 idmap = mnt_idmap(path->mnt);
774 fs_userns = i_user_ns(inode);
775
776 retry_deleg:
777 newattrs.ia_vfsuid = INVALID_VFSUID;
778 newattrs.ia_vfsgid = INVALID_VFSGID;
779 newattrs.ia_valid = ATTR_CTIME;
780 if ((user != (uid_t)-1) && !setattr_vfsuid(&newattrs, uid))
781 return -EINVAL;
782 if ((group != (gid_t)-1) && !setattr_vfsgid(&newattrs, gid))
783 return -EINVAL;
784 inode_lock(inode);
785 if (!S_ISDIR(inode->i_mode))
786 newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV |
787 setattr_should_drop_sgid(idmap, inode);
788 /* Continue to send actual fs values, not the mount values. */
789 error = security_path_chown(
790 path,
791 from_vfsuid(idmap, fs_userns, newattrs.ia_vfsuid),
792 from_vfsgid(idmap, fs_userns, newattrs.ia_vfsgid));
793 if (!error)
794 error = notify_change(idmap, path->dentry, &newattrs,
795 &delegated_inode);
796 inode_unlock(inode);
797 if (delegated_inode) {
798 error = break_deleg_wait(&delegated_inode);
799 if (!error)
800 goto retry_deleg;
801 }
802 return error;
803 }
804
805 int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
806 int flag)
807 {
808 struct path path;
809 int error = -EINVAL;
810 int lookup_flags;
811
812 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
813 goto out;
814
815 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
816 if (flag & AT_EMPTY_PATH)
817 lookup_flags |= LOOKUP_EMPTY;
818 retry:
819 error = user_path_at(dfd, filename, lookup_flags, &path);
820 if (error)
821 goto out;
822 error = mnt_want_write(path.mnt);
823 if (error)
824 goto out_release;
825 error = chown_common(&path, user, group);
826 mnt_drop_write(path.mnt);
827 out_release:
828 path_put(&path);
829 if (retry_estale(error, lookup_flags)) {
830 lookup_flags |= LOOKUP_REVAL;
831 goto retry;
832 }
833 out:
834 return error;
835 }
836
837 SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
838 gid_t, group, int, flag)
839 {
840 return do_fchownat(dfd, filename, user, group, flag);
841 }
842
843 SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
844 {
845 return do_fchownat(AT_FDCWD, filename, user, group, 0);
846 }
847
848 SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
849 {
850 return do_fchownat(AT_FDCWD, filename, user, group,
851 AT_SYMLINK_NOFOLLOW);
852 }
853
854 int vfs_fchown(struct file *file, uid_t user, gid_t group)
855 {
856 int error;
857
858 error = mnt_want_write_file(file);
859 if (error)
860 return error;
861 audit_file(file);
862 error = chown_common(&file->f_path, user, group);
863 mnt_drop_write_file(file);
864 return error;
865 }
866
867 int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
868 {
869 struct fd f = fdget(fd);
870 int error = -EBADF;
871
872 if (f.file) {
873 error = vfs_fchown(f.file, user, group);
874 fdput(f);
875 }
876 return error;
877 }
878
879 SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
880 {
881 return ksys_fchown(fd, user, group);
882 }
883
884 static inline int file_get_write_access(struct file *f)
885 {
886 int error;
887
888 error = get_write_access(f->f_inode);
889 if (unlikely(error))
890 return error;
891 error = mnt_get_write_access(f->f_path.mnt);
892 if (unlikely(error))
893 goto cleanup_inode;
894 if (unlikely(f->f_mode & FMODE_BACKING)) {
895 error = mnt_get_write_access(backing_file_user_path(f)->mnt);
896 if (unlikely(error))
897 goto cleanup_mnt;
898 }
899 return 0;
900
901 cleanup_mnt:
902 mnt_put_write_access(f->f_path.mnt);
903 cleanup_inode:
904 put_write_access(f->f_inode);
905 return error;
906 }
907
908 static int do_dentry_open(struct file *f,
909 int (*open)(struct inode *, struct file *))
910 {
911 static const struct file_operations empty_fops = {};
912 struct inode *inode = f->f_path.dentry->d_inode;
913 int error;
914
915 path_get(&f->f_path);
916 f->f_inode = inode;
917 f->f_mapping = inode->i_mapping;
918 f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
919 f->f_sb_err = file_sample_sb_err(f);
920
921 if (unlikely(f->f_flags & O_PATH)) {
922 f->f_mode = FMODE_PATH | FMODE_OPENED;
923 f->f_op = &empty_fops;
924 return 0;
925 }
926
927 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
928 i_readcount_inc(inode);
929 } else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
930 error = file_get_write_access(f);
931 if (unlikely(error))
932 goto cleanup_file;
933 f->f_mode |= FMODE_WRITER;
934 }
935
936 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
937 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
938 f->f_mode |= FMODE_ATOMIC_POS;
939
940 f->f_op = fops_get(inode->i_fop);
941 if (WARN_ON(!f->f_op)) {
942 error = -ENODEV;
943 goto cleanup_all;
944 }
945
946 error = security_file_open(f);
947 if (error)
948 goto cleanup_all;
949
950 error = break_lease(file_inode(f), f->f_flags);
951 if (error)
952 goto cleanup_all;
953
954 /* normally all 3 are set; ->open() can clear them if needed */
955 f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
956 if (!open)
957 open = f->f_op->open;
958 if (open) {
959 error = open(inode, f);
960 if (error)
961 goto cleanup_all;
962 }
963 f->f_mode |= FMODE_OPENED;
964 if ((f->f_mode & FMODE_READ) &&
965 likely(f->f_op->read || f->f_op->read_iter))
966 f->f_mode |= FMODE_CAN_READ;
967 if ((f->f_mode & FMODE_WRITE) &&
968 likely(f->f_op->write || f->f_op->write_iter))
969 f->f_mode |= FMODE_CAN_WRITE;
970 if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek)
971 f->f_mode &= ~FMODE_LSEEK;
972 if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO)
973 f->f_mode |= FMODE_CAN_ODIRECT;
974
975 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
976 f->f_iocb_flags = iocb_flags(f);
977
978 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
979
980 if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT))
981 return -EINVAL;
982
983 /*
984 * XXX: Huge page cache doesn't support writing yet. Drop all page
985 * cache for this file before processing writes.
986 */
987 if (f->f_mode & FMODE_WRITE) {
988 /*
989 * Depends on full fence from get_write_access() to synchronize
990 * against collapse_file() regarding i_writecount and nr_thps
991 * updates. Ensures subsequent insertion of THPs into the page
992 * cache will fail.
993 */
994 if (filemap_nr_thps(inode->i_mapping)) {
995 struct address_space *mapping = inode->i_mapping;
996
997 filemap_invalidate_lock(inode->i_mapping);
998 /*
999 * unmap_mapping_range just need to be called once
1000 * here, because the private pages is not need to be
1001 * unmapped mapping (e.g. data segment of dynamic
1002 * shared libraries here).
1003 */
1004 unmap_mapping_range(mapping, 0, 0, 0);
1005 truncate_inode_pages(mapping, 0);
1006 filemap_invalidate_unlock(inode->i_mapping);
1007 }
1008 }
1009
1010 return 0;
1011
1012 cleanup_all:
1013 if (WARN_ON_ONCE(error > 0))
1014 error = -EINVAL;
1015 fops_put(f->f_op);
1016 put_file_access(f);
1017 cleanup_file:
1018 path_put(&f->f_path);
1019 f->f_path.mnt = NULL;
1020 f->f_path.dentry = NULL;
1021 f->f_inode = NULL;
1022 return error;
1023 }
1024
1025 /**
1026 * finish_open - finish opening a file
1027 * @file: file pointer
1028 * @dentry: pointer to dentry
1029 * @open: open callback
1030 *
1031 * This can be used to finish opening a file passed to i_op->atomic_open().
1032 *
1033 * If the open callback is set to NULL, then the standard f_op->open()
1034 * filesystem callback is substituted.
1035 *
1036 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
1037 * the return value of d_splice_alias(), then the caller needs to perform dput()
1038 * on it after finish_open().
1039 *
1040 * Returns zero on success or -errno if the open failed.
1041 */
1042 int finish_open(struct file *file, struct dentry *dentry,
1043 int (*open)(struct inode *, struct file *))
1044 {
1045 BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
1046
1047 file->f_path.dentry = dentry;
1048 return do_dentry_open(file, open);
1049 }
1050 EXPORT_SYMBOL(finish_open);
1051
1052 /**
1053 * finish_no_open - finish ->atomic_open() without opening the file
1054 *
1055 * @file: file pointer
1056 * @dentry: dentry or NULL (as returned from ->lookup())
1057 *
1058 * This can be used to set the result of a successful lookup in ->atomic_open().
1059 *
1060 * NB: unlike finish_open() this function does consume the dentry reference and
1061 * the caller need not dput() it.
1062 *
1063 * Returns "" which must be the return value of ->atomic_open() after having
1064 * called this function.
1065 */
1066 int finish_no_open(struct file *file, struct dentry *dentry)
1067 {
1068 file->f_path.dentry = dentry;
1069 return 0;
1070 }
1071 EXPORT_SYMBOL(finish_no_open);
1072
1073 char *file_path(struct file *filp, char *buf, int buflen)
1074 {
1075 return d_path(&filp->f_path, buf, buflen);
1076 }
1077 EXPORT_SYMBOL(file_path);
1078
1079 /**
1080 * vfs_open - open the file at the given path
1081 * @path: path to open
1082 * @file: newly allocated file with f_flag initialized
1083 */
1084 int vfs_open(const struct path *path, struct file *file)
1085 {
1086 int ret;
1087
1088 file->f_path = *path;
1089 ret = do_dentry_open(file, NULL);
1090 if (!ret) {
1091 /*
1092 * Once we return a file with FMODE_OPENED, __fput() will call
1093 * fsnotify_close(), so we need fsnotify_open() here for
1094 * symmetry.
1095 */
1096 fsnotify_open(file);
1097 }
1098 return ret;
1099 }
1100
1101 struct file *dentry_open(const struct path *path, int flags,
1102 const struct cred *cred)
1103 {
1104 int error;
1105 struct file *f;
1106
1107 /* We must always pass in a valid mount pointer. */
1108 BUG_ON(!path->mnt);
1109
1110 f = alloc_empty_file(flags, cred);
1111 if (!IS_ERR(f)) {
1112 error = vfs_open(path, f);
1113 if (error) {
1114 fput(f);
1115 f = ERR_PTR(error);
1116 }
1117 }
1118 return f;
1119 }
1120 EXPORT_SYMBOL(dentry_open);
1121
1122 /**
1123 * dentry_create - Create and open a file
1124 * @path: path to create
1125 * @flags: O_ flags
1126 * @mode: mode bits for new file
1127 * @cred: credentials to use
1128 *
1129 * Caller must hold the parent directory's lock, and have prepared
1130 * a negative dentry, placed in @path->dentry, for the new file.
1131 *
1132 * Caller sets @path->mnt to the vfsmount of the filesystem where
1133 * the new file is to be created. The parent directory and the
1134 * negative dentry must reside on the same filesystem instance.
1135 *
1136 * On success, returns a "struct file *". Otherwise a ERR_PTR
1137 * is returned.
1138 */
1139 struct file *dentry_create(const struct path *path, int flags, umode_t mode,
1140 const struct cred *cred)
1141 {
1142 struct file *f;
1143 int error;
1144
1145 f = alloc_empty_file(flags, cred);
1146 if (IS_ERR(f))
1147 return f;
1148
1149 error = vfs_create(mnt_idmap(path->mnt),
1150 d_inode(path->dentry->d_parent),
1151 path->dentry, mode, true);
1152 if (!error)
1153 error = vfs_open(path, f);
1154
1155 if (unlikely(error)) {
1156 fput(f);
1157 return ERR_PTR(error);
1158 }
1159 return f;
1160 }
1161 EXPORT_SYMBOL(dentry_create);
1162
1163 /**
1164 * kernel_file_open - open a file for kernel internal use
1165 * @path: path of the file to open
1166 * @flags: open flags
1167 * @cred: credentials for open
1168 *
1169 * Open a file for use by in-kernel consumers. The file is not accounted
1170 * against nr_files and must not be installed into the file descriptor
1171 * table.
1172 *
1173 * Return: Opened file on success, an error pointer on failure.
1174 */
1175 struct file *kernel_file_open(const struct path *path, int flags,
1176 const struct cred *cred)
1177 {
1178 struct file *f;
1179 int error;
1180
1181 f = alloc_empty_file_noaccount(flags, cred);
1182 if (IS_ERR(f))
1183 return f;
1184
1185 f->f_path = *path;
1186 error = do_dentry_open(f, NULL);
1187 if (error) {
1188 fput(f);
1189 return ERR_PTR(error);
1190 }
1191
1192 fsnotify_open(f);
1193 return f;
1194 }
1195 EXPORT_SYMBOL_GPL(kernel_file_open);
1196
1197 #define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE))
1198 #define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
1199
1200 inline struct open_how build_open_how(int flags, umode_t mode)
1201 {
1202 struct open_how how = {
1203 .flags = flags & VALID_OPEN_FLAGS,
1204 .mode = mode & S_IALLUGO,
1205 };
1206
1207 /* O_PATH beats everything else. */
1208 if (how.flags & O_PATH)
1209 how.flags &= O_PATH_FLAGS;
1210 /* Modes should only be set for create-like flags. */
1211 if (!WILL_CREATE(how.flags))
1212 how.mode = 0;
1213 return how;
1214 }
1215
1216 inline int build_open_flags(const struct open_how *how, struct open_flags *op)
1217 {
1218 u64 flags = how->flags;
1219 u64 strip = __FMODE_NONOTIFY | O_CLOEXEC;
1220 int lookup_flags = 0;
1221 int acc_mode = ACC_MODE(flags);
1222
1223 BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
1224 "struct open_flags doesn't yet handle flags > 32 bits");
1225
1226 /*
1227 * Strip flags that either shouldn't be set by userspace like
1228 * FMODE_NONOTIFY or that aren't relevant in determining struct
1229 * open_flags like O_CLOEXEC.
1230 */
1231 flags &= ~strip;
1232
1233 /*
1234 * Older syscalls implicitly clear all of the invalid flags or argument
1235 * values before calling build_open_flags(), but openat2(2) checks all
1236 * of its arguments.
1237 */
1238 if (flags & ~VALID_OPEN_FLAGS)
1239 return -EINVAL;
1240 if (how->resolve & ~VALID_RESOLVE_FLAGS)
1241 return -EINVAL;
1242
1243 /* Scoping flags are mutually exclusive. */
1244 if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
1245 return -EINVAL;
1246
1247 /* Deal with the mode. */
1248 if (WILL_CREATE(flags)) {
1249 if (how->mode & ~S_IALLUGO)
1250 return -EINVAL;
1251 op->mode = how->mode | S_IFREG;
1252 } else {
1253 if (how->mode != 0)
1254 return -EINVAL;
1255 op->mode = 0;
1256 }
1257
1258 /*
1259 * Block bugs where O_DIRECTORY | O_CREAT created regular files.
1260 * Note, that blocking O_DIRECTORY | O_CREAT here also protects
1261 * O_TMPFILE below which requires O_DIRECTORY being raised.
1262 */
1263 if ((flags & (O_DIRECTORY | O_CREAT)) == (O_DIRECTORY | O_CREAT))
1264 return -EINVAL;
1265
1266 /* Now handle the creative implementation of O_TMPFILE. */
1267 if (flags & __O_TMPFILE) {
1268 /*
1269 * In order to ensure programs get explicit errors when trying
1270 * to use O_TMPFILE on old kernels we enforce that O_DIRECTORY
1271 * is raised alongside __O_TMPFILE.
1272 */
1273 if (!(flags & O_DIRECTORY))
1274 return -EINVAL;
1275 if (!(acc_mode & MAY_WRITE))
1276 return -EINVAL;
1277 }
1278 if (flags & O_PATH) {
1279 /* O_PATH only permits certain other flags to be set. */
1280 if (flags & ~O_PATH_FLAGS)
1281 return -EINVAL;
1282 acc_mode = 0;
1283 }
1284
1285 /*
1286 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1287 * check for O_DSYNC if the need any syncing at all we enforce it's
1288 * always set instead of having to deal with possibly weird behaviour
1289 * for malicious applications setting only __O_SYNC.
1290 */
1291 if (flags & __O_SYNC)
1292 flags |= O_DSYNC;
1293
1294 op->open_flag = flags;
1295
1296 /* O_TRUNC implies we need access checks for write permissions */
1297 if (flags & O_TRUNC)
1298 acc_mode |= MAY_WRITE;
1299
1300 /* Allow the LSM permission hook to distinguish append
1301 access from general write access. */
1302 if (flags & O_APPEND)
1303 acc_mode |= MAY_APPEND;
1304
1305 op->acc_mode = acc_mode;
1306
1307 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1308
1309 if (flags & O_CREAT) {
1310 op->intent |= LOOKUP_CREATE;
1311 if (flags & O_EXCL) {
1312 op->intent |= LOOKUP_EXCL;
1313 flags |= O_NOFOLLOW;
1314 }
1315 }
1316
1317 if (flags & O_DIRECTORY)
1318 lookup_flags |= LOOKUP_DIRECTORY;
1319 if (!(flags & O_NOFOLLOW))
1320 lookup_flags |= LOOKUP_FOLLOW;
1321
1322 if (how->resolve & RESOLVE_NO_XDEV)
1323 lookup_flags |= LOOKUP_NO_XDEV;
1324 if (how->resolve & RESOLVE_NO_MAGICLINKS)
1325 lookup_flags |= LOOKUP_NO_MAGICLINKS;
1326 if (how->resolve & RESOLVE_NO_SYMLINKS)
1327 lookup_flags |= LOOKUP_NO_SYMLINKS;
1328 if (how->resolve & RESOLVE_BENEATH)
1329 lookup_flags |= LOOKUP_BENEATH;
1330 if (how->resolve & RESOLVE_IN_ROOT)
1331 lookup_flags |= LOOKUP_IN_ROOT;
1332 if (how->resolve & RESOLVE_CACHED) {
1333 /* Don't bother even trying for create/truncate/tmpfile open */
1334 if (flags & (O_TRUNC | O_CREAT | __O_TMPFILE))
1335 return -EAGAIN;
1336 lookup_flags |= LOOKUP_CACHED;
1337 }
1338
1339 op->lookup_flags = lookup_flags;
1340 return 0;
1341 }
1342
1343 /**
1344 * file_open_name - open file and return file pointer
1345 *
1346 * @name: struct filename containing path to open
1347 * @flags: open flags as per the open(2) second argument
1348 * @mode: mode for the new file if O_CREAT is set, else ignored
1349 *
1350 * This is the helper to open a file from kernelspace if you really
1351 * have to. But in generally you should not do this, so please move
1352 * along, nothing to see here..
1353 */
1354 struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1355 {
1356 struct open_flags op;
1357 struct open_how how = build_open_how(flags, mode);
1358 int err = build_open_flags(&how, &op);
1359 if (err)
1360 return ERR_PTR(err);
1361 return do_filp_open(AT_FDCWD, name, &op);
1362 }
1363
1364 /**
1365 * filp_open - open file and return file pointer
1366 *
1367 * @filename: path to open
1368 * @flags: open flags as per the open(2) second argument
1369 * @mode: mode for the new file if O_CREAT is set, else ignored
1370 *
1371 * This is the helper to open a file from kernelspace if you really
1372 * have to. But in generally you should not do this, so please move
1373 * along, nothing to see here..
1374 */
1375 struct file *filp_open(const char *filename, int flags, umode_t mode)
1376 {
1377 struct filename *name = getname_kernel(filename);
1378 struct file *file = ERR_CAST(name);
1379
1380 if (!IS_ERR(name)) {
1381 file = file_open_name(name, flags, mode);
1382 putname(name);
1383 }
1384 return file;
1385 }
1386 EXPORT_SYMBOL(filp_open);
1387
1388 struct file *file_open_root(const struct path *root,
1389 const char *filename, int flags, umode_t mode)
1390 {
1391 struct open_flags op;
1392 struct open_how how = build_open_how(flags, mode);
1393 int err = build_open_flags(&how, &op);
1394 if (err)
1395 return ERR_PTR(err);
1396 return do_file_open_root(root, filename, &op);
1397 }
1398 EXPORT_SYMBOL(file_open_root);
1399
1400 static long do_sys_openat2(int dfd, const char __user *filename,
1401 struct open_how *how)
1402 {
1403 struct open_flags op;
1404 int fd = build_open_flags(how, &op);
1405 struct filename *tmp;
1406
1407 if (fd)
1408 return fd;
1409
1410 tmp = getname(filename);
1411 if (IS_ERR(tmp))
1412 return PTR_ERR(tmp);
1413
1414 fd = get_unused_fd_flags(how->flags);
1415 if (fd >= 0) {
1416 struct file *f = do_filp_open(dfd, tmp, &op);
1417 if (IS_ERR(f)) {
1418 put_unused_fd(fd);
1419 fd = PTR_ERR(f);
1420 } else {
1421 fd_install(fd, f);
1422 }
1423 }
1424 putname(tmp);
1425 return fd;
1426 }
1427
1428 long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1429 {
1430 struct open_how how = build_open_how(flags, mode);
1431 return do_sys_openat2(dfd, filename, &how);
1432 }
1433
1434
1435 SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1436 {
1437 if (force_o_largefile())
1438 flags |= O_LARGEFILE;
1439 return do_sys_open(AT_FDCWD, filename, flags, mode);
1440 }
1441
1442 SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1443 umode_t, mode)
1444 {
1445 if (force_o_largefile())
1446 flags |= O_LARGEFILE;
1447 return do_sys_open(dfd, filename, flags, mode);
1448 }
1449
1450 SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1451 struct open_how __user *, how, size_t, usize)
1452 {
1453 int err;
1454 struct open_how tmp;
1455
1456 BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1457 BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1458
1459 if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1460 return -EINVAL;
1461
1462 err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
1463 if (err)
1464 return err;
1465
1466 audit_openat2_how(&tmp);
1467
1468 /* O_LARGEFILE is only allowed for non-O_PATH. */
1469 if (!(tmp.flags & O_PATH) && force_o_largefile())
1470 tmp.flags |= O_LARGEFILE;
1471
1472 return do_sys_openat2(dfd, filename, &tmp);
1473 }
1474
1475 #ifdef CONFIG_COMPAT
1476 /*
1477 * Exactly like sys_open(), except that it doesn't set the
1478 * O_LARGEFILE flag.
1479 */
1480 COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1481 {
1482 return do_sys_open(AT_FDCWD, filename, flags, mode);
1483 }
1484
1485 /*
1486 * Exactly like sys_openat(), except that it doesn't set the
1487 * O_LARGEFILE flag.
1488 */
1489 COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1490 {
1491 return do_sys_open(dfd, filename, flags, mode);
1492 }
1493 #endif
1494
1495 #ifndef __alpha__
1496
1497 /*
1498 * For backward compatibility? Maybe this should be moved
1499 * into arch/i386 instead?
1500 */
1501 SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1502 {
1503 int flags = O_CREAT | O_WRONLY | O_TRUNC;
1504
1505 if (force_o_largefile())
1506 flags |= O_LARGEFILE;
1507 return do_sys_open(AT_FDCWD, pathname, flags, mode);
1508 }
1509 #endif
1510
1511 /*
1512 * "id" is the POSIX thread ID. We use the
1513 * files pointer for this..
1514 */
1515 static int filp_flush(struct file *filp, fl_owner_t id)
1516 {
1517 int retval = 0;
1518
1519 if (CHECK_DATA_CORRUPTION(file_count(filp) == 0,
1520 "VFS: Close: file count is 0 (f_op=%ps)",
1521 filp->f_op)) {
1522 return 0;
1523 }
1524
1525 if (filp->f_op->flush)
1526 retval = filp->f_op->flush(filp, id);
1527
1528 if (likely(!(filp->f_mode & FMODE_PATH))) {
1529 dnotify_flush(filp, id);
1530 locks_remove_posix(filp, id);
1531 }
1532 return retval;
1533 }
1534
1535 int filp_close(struct file *filp, fl_owner_t id)
1536 {
1537 int retval;
1538
1539 retval = filp_flush(filp, id);
1540 fput(filp);
1541
1542 return retval;
1543 }
1544 EXPORT_SYMBOL(filp_close);
1545
1546 /*
1547 * Careful here! We test whether the file pointer is NULL before
1548 * releasing the fd. This ensures that one clone task can't release
1549 * an fd while another clone is opening it.
1550 */
1551 SYSCALL_DEFINE1(close, unsigned int, fd)
1552 {
1553 int retval;
1554 struct file *file;
1555
1556 file = file_close_fd(fd);
1557 if (!file)
1558 return -EBADF;
1559
1560 retval = filp_flush(file, current->files);
1561
1562 /*
1563 * We're returning to user space. Don't bother
1564 * with any delayed fput() cases.
1565 */
1566 __fput_sync(file);
1567
1568 /* can't restart close syscall because file table entry was cleared */
1569 if (unlikely(retval == -ERESTARTSYS ||
1570 retval == -ERESTARTNOINTR ||
1571 retval == -ERESTARTNOHAND ||
1572 retval == -ERESTART_RESTARTBLOCK))
1573 retval = -EINTR;
1574
1575 return retval;
1576 }
1577
1578 /**
1579 * sys_close_range() - Close all file descriptors in a given range.
1580 *
1581 * @fd: starting file descriptor to close
1582 * @max_fd: last file descriptor to close
1583 * @flags: reserved for future extensions
1584 *
1585 * This closes a range of file descriptors. All file descriptors
1586 * from @fd up to and including @max_fd are closed.
1587 * Currently, errors to close a given file descriptor are ignored.
1588 */
1589 SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
1590 unsigned int, flags)
1591 {
1592 return __close_range(fd, max_fd, flags);
1593 }
1594
1595 /*
1596 * This routine simulates a hangup on the tty, to arrange that users
1597 * are given clean terminals at login time.
1598 */
1599 SYSCALL_DEFINE0(vhangup)
1600 {
1601 if (!ccs_capable(CCS_SYS_VHANGUP))
1602 return -EPERM;
1603 if (capable(CAP_SYS_TTY_CONFIG)) {
1604 tty_vhangup_self();
1605 return 0;
1606 }
1607 return -EPERM;
1608 }
1609
1610 /*
1611 * Called when an inode is about to be open.
1612 * We use this to disallow opening large files on 32bit systems if
1613 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1614 * on this flag in sys_open.
1615 */
1616 int generic_file_open(struct inode * inode, struct file * filp)
1617 {
1618 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1619 return -EOVERFLOW;
1620 return 0;
1621 }
1622
1623 EXPORT_SYMBOL(generic_file_open);
1624
1625 /*
1626 * This is used by subsystems that don't want seekable
1627 * file descriptors. The function is not supposed to ever fail, the only
1628 * reason it returns an 'int' and not 'void' is so that it can be plugged
1629 * directly into file_operations structure.
1630 */
1631 int nonseekable_open(struct inode *inode, struct file *filp)
1632 {
1633 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1634 return 0;
1635 }
1636
1637 EXPORT_SYMBOL(nonseekable_open);
1638
1639 /*
1640 * stream_open is used by subsystems that want stream-like file descriptors.
1641 * Such file descriptors are not seekable and don't have notion of position
1642 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1643 * Contrary to file descriptors of other regular files, .read() and .write()
1644 * can run simultaneously.
1645 *
1646 * stream_open never fails and is marked to return int so that it could be
1647 * directly used as file_operations.open .
1648 */
1649 int stream_open(struct inode *inode, struct file *filp)
1650 {
1651 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1652 filp->f_mode |= FMODE_STREAM;
1653 return 0;
1654 }
1655
1656 EXPORT_SYMBOL(stream_open);
1657
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