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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/open.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8#include <linux/string.h>
9#include <linux/mm.h>
10#include <linux/file.h>
11#include <linux/fdtable.h>
12#include <linux/fsnotify.h>
13#include <linux/module.h>
14#include <linux/tty.h>
15#include <linux/namei.h>
16#include <linux/backing-dev.h>
17#include <linux/capability.h>
18#include <linux/securebits.h>
19#include <linux/security.h>
20#include <linux/mount.h>
21#include <linux/fcntl.h>
22#include <linux/slab.h>
23#include <linux/uaccess.h>
24#include <linux/fs.h>
25#include <linux/personality.h>
26#include <linux/pagemap.h>
27#include <linux/syscalls.h>
28#include <linux/rcupdate.h>
29#include <linux/audit.h>
30#include <linux/falloc.h>
31#include <linux/fs_struct.h>
32#include <linux/ima.h>
33#include <linux/dnotify.h>
34#include <linux/compat.h>
35#include <linux/mnt_idmapping.h>
36#include <linux/filelock.h>
37
38#include "internal.h"
39
40int do_truncate(struct mnt_idmap *idmap, struct dentry *dentry,
41 loff_t length, unsigned int time_attrs, struct file *filp)
42{
43 int ret;
44 struct iattr newattrs;
45
46 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
47 if (length < 0)
48 return -EINVAL;
49
50 newattrs.ia_size = length;
51 newattrs.ia_valid = ATTR_SIZE | time_attrs;
52 if (filp) {
53 newattrs.ia_file = filp;
54 newattrs.ia_valid |= ATTR_FILE;
55 }
56
57 /* Remove suid, sgid, and file capabilities on truncate too */
58 ret = dentry_needs_remove_privs(idmap, dentry);
59 if (ret < 0)
60 return ret;
61 if (ret)
62 newattrs.ia_valid |= ret | ATTR_FORCE;
63
64 inode_lock(dentry->d_inode);
65 /* Note any delegations or leases have already been broken: */
66 ret = notify_change(idmap, dentry, &newattrs, NULL);
67 inode_unlock(dentry->d_inode);
68 return ret;
69}
70
71long vfs_truncate(const struct path *path, loff_t length)
72{
73 struct mnt_idmap *idmap;
74 struct inode *inode;
75 long error;
76
77 inode = path->dentry->d_inode;
78
79 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
80 if (S_ISDIR(inode->i_mode))
81 return -EISDIR;
82 if (!S_ISREG(inode->i_mode))
83 return -EINVAL;
84
85 error = mnt_want_write(path->mnt);
86 if (error)
87 goto out;
88
89 idmap = mnt_idmap(path->mnt);
90 error = inode_permission(idmap, inode, MAY_WRITE);
91 if (error)
92 goto mnt_drop_write_and_out;
93
94 error = -EPERM;
95 if (IS_APPEND(inode))
96 goto mnt_drop_write_and_out;
97
98 error = get_write_access(inode);
99 if (error)
100 goto mnt_drop_write_and_out;
101
102 /*
103 * Make sure that there are no leases. get_write_access() protects
104 * against the truncate racing with a lease-granting setlease().
105 */
106 error = break_lease(inode, O_WRONLY);
107 if (error)
108 goto put_write_and_out;
109
110 error = security_path_truncate(path);
111 if (!error)
112 error = do_truncate(idmap, 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 = security_file_truncate(f.file);
193 if (!error)
194 error = do_truncate(file_mnt_idmap(f.file), dentry, length,
195 ATTR_MTIME | ATTR_CTIME, f.file);
196 sb_end_write(inode->i_sb);
197out_putf:
198 fdput(f);
199out:
200 return error;
201}
202
203SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
204{
205 return do_sys_ftruncate(fd, length, 1);
206}
207
208#ifdef CONFIG_COMPAT
209COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
210{
211 return do_sys_ftruncate(fd, length, 1);
212}
213#endif
214
215/* LFS versions of truncate are only needed on 32 bit machines */
216#if BITS_PER_LONG == 32
217SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
218{
219 return do_sys_truncate(path, length);
220}
221
222SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
223{
224 return do_sys_ftruncate(fd, length, 0);
225}
226#endif /* BITS_PER_LONG == 32 */
227
228#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64)
229COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname,
230 compat_arg_u64_dual(length))
231{
232 return ksys_truncate(pathname, compat_arg_u64_glue(length));
233}
234#endif
235
236#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64)
237COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd,
238 compat_arg_u64_dual(length))
239{
240 return ksys_ftruncate(fd, compat_arg_u64_glue(length));
241}
242#endif
243
244int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
245{
246 struct inode *inode = file_inode(file);
247 long ret;
248
249 if (offset < 0 || len <= 0)
250 return -EINVAL;
251
252 /* Return error if mode is not supported */
253 if (mode & ~FALLOC_FL_SUPPORTED_MASK)
254 return -EOPNOTSUPP;
255
256 /* Punch hole and zero range are mutually exclusive */
257 if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
258 (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
259 return -EOPNOTSUPP;
260
261 /* Punch hole must have keep size set */
262 if ((mode & FALLOC_FL_PUNCH_HOLE) &&
263 !(mode & FALLOC_FL_KEEP_SIZE))
264 return -EOPNOTSUPP;
265
266 /* Collapse range should only be used exclusively. */
267 if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
268 (mode & ~FALLOC_FL_COLLAPSE_RANGE))
269 return -EINVAL;
270
271 /* Insert range should only be used exclusively. */
272 if ((mode & FALLOC_FL_INSERT_RANGE) &&
273 (mode & ~FALLOC_FL_INSERT_RANGE))
274 return -EINVAL;
275
276 /* Unshare range should only be used with allocate mode. */
277 if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
278 (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
279 return -EINVAL;
280
281 if (!(file->f_mode & FMODE_WRITE))
282 return -EBADF;
283
284 /*
285 * We can only allow pure fallocate on append only files
286 */
287 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
288 return -EPERM;
289
290 if (IS_IMMUTABLE(inode))
291 return -EPERM;
292
293 /*
294 * We cannot allow any fallocate operation on an active swapfile
295 */
296 if (IS_SWAPFILE(inode))
297 return -ETXTBSY;
298
299 /*
300 * Revalidate the write permissions, in case security policy has
301 * changed since the files were opened.
302 */
303 ret = security_file_permission(file, MAY_WRITE);
304 if (ret)
305 return ret;
306
307 ret = fsnotify_file_area_perm(file, MAY_WRITE, &offset, len);
308 if (ret)
309 return ret;
310
311 if (S_ISFIFO(inode->i_mode))
312 return -ESPIPE;
313
314 if (S_ISDIR(inode->i_mode))
315 return -EISDIR;
316
317 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
318 return -ENODEV;
319
320 /* Check for wrap through zero too */
321 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
322 return -EFBIG;
323
324 if (!file->f_op->fallocate)
325 return -EOPNOTSUPP;
326
327 file_start_write(file);
328 ret = file->f_op->fallocate(file, mode, offset, len);
329
330 /*
331 * Create inotify and fanotify events.
332 *
333 * To keep the logic simple always create events if fallocate succeeds.
334 * This implies that events are even created if the file size remains
335 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
336 */
337 if (ret == 0)
338 fsnotify_modify(file);
339
340 file_end_write(file);
341 return ret;
342}
343EXPORT_SYMBOL_GPL(vfs_fallocate);
344
345int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
346{
347 struct fd f = fdget(fd);
348 int error = -EBADF;
349
350 if (f.file) {
351 error = vfs_fallocate(f.file, mode, offset, len);
352 fdput(f);
353 }
354 return error;
355}
356
357SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
358{
359 return ksys_fallocate(fd, mode, offset, len);
360}
361
362#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE)
363COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset),
364 compat_arg_u64_dual(len))
365{
366 return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset),
367 compat_arg_u64_glue(len));
368}
369#endif
370
371/*
372 * access() needs to use the real uid/gid, not the effective uid/gid.
373 * We do this by temporarily clearing all FS-related capabilities and
374 * switching the fsuid/fsgid around to the real ones.
375 *
376 * Creating new credentials is expensive, so we try to skip doing it,
377 * which we can if the result would match what we already got.
378 */
379static bool access_need_override_creds(int flags)
380{
381 const struct cred *cred;
382
383 if (flags & AT_EACCESS)
384 return false;
385
386 cred = current_cred();
387 if (!uid_eq(cred->fsuid, cred->uid) ||
388 !gid_eq(cred->fsgid, cred->gid))
389 return true;
390
391 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
392 kuid_t root_uid = make_kuid(cred->user_ns, 0);
393 if (!uid_eq(cred->uid, root_uid)) {
394 if (!cap_isclear(cred->cap_effective))
395 return true;
396 } else {
397 if (!cap_isidentical(cred->cap_effective,
398 cred->cap_permitted))
399 return true;
400 }
401 }
402
403 return false;
404}
405
406static const struct cred *access_override_creds(void)
407{
408 const struct cred *old_cred;
409 struct cred *override_cred;
410
411 override_cred = prepare_creds();
412 if (!override_cred)
413 return NULL;
414
415 /*
416 * XXX access_need_override_creds performs checks in hopes of skipping
417 * this work. Make sure it stays in sync if making any changes in this
418 * routine.
419 */
420
421 override_cred->fsuid = override_cred->uid;
422 override_cred->fsgid = override_cred->gid;
423
424 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
425 /* Clear the capabilities if we switch to a non-root user */
426 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
427 if (!uid_eq(override_cred->uid, root_uid))
428 cap_clear(override_cred->cap_effective);
429 else
430 override_cred->cap_effective =
431 override_cred->cap_permitted;
432 }
433
434 /*
435 * The new set of credentials can *only* be used in
436 * task-synchronous circumstances, and does not need
437 * RCU freeing, unless somebody then takes a separate
438 * reference to it.
439 *
440 * NOTE! This is _only_ true because this credential
441 * is used purely for override_creds() that installs
442 * it as the subjective cred. Other threads will be
443 * accessing ->real_cred, not the subjective cred.
444 *
445 * If somebody _does_ make a copy of this (using the
446 * 'get_current_cred()' function), that will clear the
447 * non_rcu field, because now that other user may be
448 * expecting RCU freeing. But normal thread-synchronous
449 * cred accesses will keep things non-racy to avoid RCU
450 * freeing.
451 */
452 override_cred->non_rcu = 1;
453
454 old_cred = override_creds(override_cred);
455
456 /* override_cred() gets its own ref */
457 put_cred(override_cred);
458
459 return old_cred;
460}
461
462static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
463{
464 struct path path;
465 struct inode *inode;
466 int res;
467 unsigned int lookup_flags = LOOKUP_FOLLOW;
468 const struct cred *old_cred = NULL;
469
470 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
471 return -EINVAL;
472
473 if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
474 return -EINVAL;
475
476 if (flags & AT_SYMLINK_NOFOLLOW)
477 lookup_flags &= ~LOOKUP_FOLLOW;
478 if (flags & AT_EMPTY_PATH)
479 lookup_flags |= LOOKUP_EMPTY;
480
481 if (access_need_override_creds(flags)) {
482 old_cred = access_override_creds();
483 if (!old_cred)
484 return -ENOMEM;
485 }
486
487retry:
488 res = user_path_at(dfd, filename, lookup_flags, &path);
489 if (res)
490 goto out;
491
492 inode = d_backing_inode(path.dentry);
493
494 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
495 /*
496 * MAY_EXEC on regular files is denied if the fs is mounted
497 * with the "noexec" flag.
498 */
499 res = -EACCES;
500 if (path_noexec(&path))
501 goto out_path_release;
502 }
503
504 res = inode_permission(mnt_idmap(path.mnt), inode, mode | MAY_ACCESS);
505 /* SuS v2 requires we report a read only fs too */
506 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
507 goto out_path_release;
508 /*
509 * This is a rare case where using __mnt_is_readonly()
510 * is OK without a mnt_want/drop_write() pair. Since
511 * no actual write to the fs is performed here, we do
512 * not need to telegraph to that to anyone.
513 *
514 * By doing this, we accept that this access is
515 * inherently racy and know that the fs may change
516 * state before we even see this result.
517 */
518 if (__mnt_is_readonly(path.mnt))
519 res = -EROFS;
520
521out_path_release:
522 path_put(&path);
523 if (retry_estale(res, lookup_flags)) {
524 lookup_flags |= LOOKUP_REVAL;
525 goto retry;
526 }
527out:
528 if (old_cred)
529 revert_creds(old_cred);
530
531 return res;
532}
533
534SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
535{
536 return do_faccessat(dfd, filename, mode, 0);
537}
538
539SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
540 int, flags)
541{
542 return do_faccessat(dfd, filename, mode, flags);
543}
544
545SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
546{
547 return do_faccessat(AT_FDCWD, filename, mode, 0);
548}
549
550SYSCALL_DEFINE1(chdir, const char __user *, filename)
551{
552 struct path path;
553 int error;
554 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
555retry:
556 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
557 if (error)
558 goto out;
559
560 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
561 if (error)
562 goto dput_and_out;
563
564 set_fs_pwd(current->fs, &path);
565
566dput_and_out:
567 path_put(&path);
568 if (retry_estale(error, lookup_flags)) {
569 lookup_flags |= LOOKUP_REVAL;
570 goto retry;
571 }
572out:
573 return error;
574}
575
576SYSCALL_DEFINE1(fchdir, unsigned int, fd)
577{
578 struct fd f = fdget_raw(fd);
579 int error;
580
581 error = -EBADF;
582 if (!f.file)
583 goto out;
584
585 error = -ENOTDIR;
586 if (!d_can_lookup(f.file->f_path.dentry))
587 goto out_putf;
588
589 error = file_permission(f.file, MAY_EXEC | MAY_CHDIR);
590 if (!error)
591 set_fs_pwd(current->fs, &f.file->f_path);
592out_putf:
593 fdput(f);
594out:
595 return error;
596}
597
598SYSCALL_DEFINE1(chroot, const char __user *, filename)
599{
600 struct path path;
601 int error;
602 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
603retry:
604 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
605 if (error)
606 goto out;
607
608 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
609 if (error)
610 goto dput_and_out;
611
612 error = -EPERM;
613 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
614 goto dput_and_out;
615 error = security_path_chroot(&path);
616 if (error)
617 goto dput_and_out;
618
619 set_fs_root(current->fs, &path);
620 error = 0;
621dput_and_out:
622 path_put(&path);
623 if (retry_estale(error, lookup_flags)) {
624 lookup_flags |= LOOKUP_REVAL;
625 goto retry;
626 }
627out:
628 return error;
629}
630
631int chmod_common(const struct path *path, umode_t mode)
632{
633 struct inode *inode = path->dentry->d_inode;
634 struct inode *delegated_inode = NULL;
635 struct iattr newattrs;
636 int error;
637
638 error = mnt_want_write(path->mnt);
639 if (error)
640 return error;
641retry_deleg:
642 inode_lock(inode);
643 error = security_path_chmod(path, mode);
644 if (error)
645 goto out_unlock;
646 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
647 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
648 error = notify_change(mnt_idmap(path->mnt), path->dentry,
649 &newattrs, &delegated_inode);
650out_unlock:
651 inode_unlock(inode);
652 if (delegated_inode) {
653 error = break_deleg_wait(&delegated_inode);
654 if (!error)
655 goto retry_deleg;
656 }
657 mnt_drop_write(path->mnt);
658 return error;
659}
660
661int vfs_fchmod(struct file *file, umode_t mode)
662{
663 audit_file(file);
664 return chmod_common(&file->f_path, mode);
665}
666
667SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
668{
669 struct fd f = fdget(fd);
670 int err = -EBADF;
671
672 if (f.file) {
673 err = vfs_fchmod(f.file, mode);
674 fdput(f);
675 }
676 return err;
677}
678
679static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
680 unsigned int flags)
681{
682 struct path path;
683 int error;
684 unsigned int lookup_flags;
685
686 if (unlikely(flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)))
687 return -EINVAL;
688
689 lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
690 if (flags & AT_EMPTY_PATH)
691 lookup_flags |= LOOKUP_EMPTY;
692
693retry:
694 error = user_path_at(dfd, filename, lookup_flags, &path);
695 if (!error) {
696 error = chmod_common(&path, mode);
697 path_put(&path);
698 if (retry_estale(error, lookup_flags)) {
699 lookup_flags |= LOOKUP_REVAL;
700 goto retry;
701 }
702 }
703 return error;
704}
705
706SYSCALL_DEFINE4(fchmodat2, int, dfd, const char __user *, filename,
707 umode_t, mode, unsigned int, flags)
708{
709 return do_fchmodat(dfd, filename, mode, flags);
710}
711
712SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
713 umode_t, mode)
714{
715 return do_fchmodat(dfd, filename, mode, 0);
716}
717
718SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
719{
720 return do_fchmodat(AT_FDCWD, filename, mode, 0);
721}
722
723/*
724 * Check whether @kuid is valid and if so generate and set vfsuid_t in
725 * ia_vfsuid.
726 *
727 * Return: true if @kuid is valid, false if not.
728 */
729static inline bool setattr_vfsuid(struct iattr *attr, kuid_t kuid)
730{
731 if (!uid_valid(kuid))
732 return false;
733 attr->ia_valid |= ATTR_UID;
734 attr->ia_vfsuid = VFSUIDT_INIT(kuid);
735 return true;
736}
737
738/*
739 * Check whether @kgid is valid and if so generate and set vfsgid_t in
740 * ia_vfsgid.
741 *
742 * Return: true if @kgid is valid, false if not.
743 */
744static inline bool setattr_vfsgid(struct iattr *attr, kgid_t kgid)
745{
746 if (!gid_valid(kgid))
747 return false;
748 attr->ia_valid |= ATTR_GID;
749 attr->ia_vfsgid = VFSGIDT_INIT(kgid);
750 return true;
751}
752
753int chown_common(const struct path *path, uid_t user, gid_t group)
754{
755 struct mnt_idmap *idmap;
756 struct user_namespace *fs_userns;
757 struct inode *inode = path->dentry->d_inode;
758 struct inode *delegated_inode = NULL;
759 int error;
760 struct iattr newattrs;
761 kuid_t uid;
762 kgid_t gid;
763
764 uid = make_kuid(current_user_ns(), user);
765 gid = make_kgid(current_user_ns(), group);
766
767 idmap = mnt_idmap(path->mnt);
768 fs_userns = i_user_ns(inode);
769
770retry_deleg:
771 newattrs.ia_vfsuid = INVALID_VFSUID;
772 newattrs.ia_vfsgid = INVALID_VFSGID;
773 newattrs.ia_valid = ATTR_CTIME;
774 if ((user != (uid_t)-1) && !setattr_vfsuid(&newattrs, uid))
775 return -EINVAL;
776 if ((group != (gid_t)-1) && !setattr_vfsgid(&newattrs, gid))
777 return -EINVAL;
778 inode_lock(inode);
779 if (!S_ISDIR(inode->i_mode))
780 newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV |
781 setattr_should_drop_sgid(idmap, inode);
782 /* Continue to send actual fs values, not the mount values. */
783 error = security_path_chown(
784 path,
785 from_vfsuid(idmap, fs_userns, newattrs.ia_vfsuid),
786 from_vfsgid(idmap, fs_userns, newattrs.ia_vfsgid));
787 if (!error)
788 error = notify_change(idmap, path->dentry, &newattrs,
789 &delegated_inode);
790 inode_unlock(inode);
791 if (delegated_inode) {
792 error = break_deleg_wait(&delegated_inode);
793 if (!error)
794 goto retry_deleg;
795 }
796 return error;
797}
798
799int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
800 int flag)
801{
802 struct path path;
803 int error = -EINVAL;
804 int lookup_flags;
805
806 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
807 goto out;
808
809 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
810 if (flag & AT_EMPTY_PATH)
811 lookup_flags |= LOOKUP_EMPTY;
812retry:
813 error = user_path_at(dfd, filename, lookup_flags, &path);
814 if (error)
815 goto out;
816 error = mnt_want_write(path.mnt);
817 if (error)
818 goto out_release;
819 error = chown_common(&path, user, group);
820 mnt_drop_write(path.mnt);
821out_release:
822 path_put(&path);
823 if (retry_estale(error, lookup_flags)) {
824 lookup_flags |= LOOKUP_REVAL;
825 goto retry;
826 }
827out:
828 return error;
829}
830
831SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
832 gid_t, group, int, flag)
833{
834 return do_fchownat(dfd, filename, user, group, flag);
835}
836
837SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
838{
839 return do_fchownat(AT_FDCWD, filename, user, group, 0);
840}
841
842SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
843{
844 return do_fchownat(AT_FDCWD, filename, user, group,
845 AT_SYMLINK_NOFOLLOW);
846}
847
848int vfs_fchown(struct file *file, uid_t user, gid_t group)
849{
850 int error;
851
852 error = mnt_want_write_file(file);
853 if (error)
854 return error;
855 audit_file(file);
856 error = chown_common(&file->f_path, user, group);
857 mnt_drop_write_file(file);
858 return error;
859}
860
861int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
862{
863 struct fd f = fdget(fd);
864 int error = -EBADF;
865
866 if (f.file) {
867 error = vfs_fchown(f.file, user, group);
868 fdput(f);
869 }
870 return error;
871}
872
873SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
874{
875 return ksys_fchown(fd, user, group);
876}
877
878static inline int file_get_write_access(struct file *f)
879{
880 int error;
881
882 error = get_write_access(f->f_inode);
883 if (unlikely(error))
884 return error;
885 error = mnt_get_write_access(f->f_path.mnt);
886 if (unlikely(error))
887 goto cleanup_inode;
888 if (unlikely(f->f_mode & FMODE_BACKING)) {
889 error = mnt_get_write_access(backing_file_user_path(f)->mnt);
890 if (unlikely(error))
891 goto cleanup_mnt;
892 }
893 return 0;
894
895cleanup_mnt:
896 mnt_put_write_access(f->f_path.mnt);
897cleanup_inode:
898 put_write_access(f->f_inode);
899 return error;
900}
901
902static int do_dentry_open(struct file *f,
903 struct inode *inode,
904 int (*open)(struct inode *, struct file *))
905{
906 static const struct file_operations empty_fops = {};
907 int error;
908
909 path_get(&f->f_path);
910 f->f_inode = inode;
911 f->f_mapping = inode->i_mapping;
912 f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
913 f->f_sb_err = file_sample_sb_err(f);
914
915 if (unlikely(f->f_flags & O_PATH)) {
916 f->f_mode = FMODE_PATH | FMODE_OPENED;
917 f->f_op = &empty_fops;
918 return 0;
919 }
920
921 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
922 i_readcount_inc(inode);
923 } else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
924 error = file_get_write_access(f);
925 if (unlikely(error))
926 goto cleanup_file;
927 f->f_mode |= FMODE_WRITER;
928 }
929
930 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
931 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
932 f->f_mode |= FMODE_ATOMIC_POS;
933
934 f->f_op = fops_get(inode->i_fop);
935 if (WARN_ON(!f->f_op)) {
936 error = -ENODEV;
937 goto cleanup_all;
938 }
939
940 error = security_file_open(f);
941 if (error)
942 goto cleanup_all;
943
944 error = break_lease(file_inode(f), f->f_flags);
945 if (error)
946 goto cleanup_all;
947
948 /* normally all 3 are set; ->open() can clear them if needed */
949 f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
950 if (!open)
951 open = f->f_op->open;
952 if (open) {
953 error = open(inode, f);
954 if (error)
955 goto cleanup_all;
956 }
957 f->f_mode |= FMODE_OPENED;
958 if ((f->f_mode & FMODE_READ) &&
959 likely(f->f_op->read || f->f_op->read_iter))
960 f->f_mode |= FMODE_CAN_READ;
961 if ((f->f_mode & FMODE_WRITE) &&
962 likely(f->f_op->write || f->f_op->write_iter))
963 f->f_mode |= FMODE_CAN_WRITE;
964 if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek)
965 f->f_mode &= ~FMODE_LSEEK;
966 if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO)
967 f->f_mode |= FMODE_CAN_ODIRECT;
968
969 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
970 f->f_iocb_flags = iocb_flags(f);
971
972 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
973
974 if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT))
975 return -EINVAL;
976
977 /*
978 * XXX: Huge page cache doesn't support writing yet. Drop all page
979 * cache for this file before processing writes.
980 */
981 if (f->f_mode & FMODE_WRITE) {
982 /*
983 * Paired with smp_mb() in collapse_file() to ensure nr_thps
984 * is up to date and the update to i_writecount by
985 * get_write_access() is visible. Ensures subsequent insertion
986 * of THPs into the page cache will fail.
987 */
988 smp_mb();
989 if (filemap_nr_thps(inode->i_mapping)) {
990 struct address_space *mapping = inode->i_mapping;
991
992 filemap_invalidate_lock(inode->i_mapping);
993 /*
994 * unmap_mapping_range just need to be called once
995 * here, because the private pages is not need to be
996 * unmapped mapping (e.g. data segment of dynamic
997 * shared libraries here).
998 */
999 unmap_mapping_range(mapping, 0, 0, 0);
1000 truncate_inode_pages(mapping, 0);
1001 filemap_invalidate_unlock(inode->i_mapping);
1002 }
1003 }
1004
1005 /*
1006 * Once we return a file with FMODE_OPENED, __fput() will call
1007 * fsnotify_close(), so we need fsnotify_open() here for symmetry.
1008 */
1009 fsnotify_open(f);
1010 return 0;
1011
1012cleanup_all:
1013 if (WARN_ON_ONCE(error > 0))
1014 error = -EINVAL;
1015 fops_put(f->f_op);
1016 put_file_access(f);
1017cleanup_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 */
1042int 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, d_backing_inode(dentry), open);
1049}
1050EXPORT_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 "0" which must be the return value of ->atomic_open() after having
1064 * called this function.
1065 */
1066int finish_no_open(struct file *file, struct dentry *dentry)
1067{
1068 file->f_path.dentry = dentry;
1069 return 0;
1070}
1071EXPORT_SYMBOL(finish_no_open);
1072
1073char *file_path(struct file *filp, char *buf, int buflen)
1074{
1075 return d_path(&filp->f_path, buf, buflen);
1076}
1077EXPORT_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 */
1084int vfs_open(const struct path *path, struct file *file)
1085{
1086 file->f_path = *path;
1087 return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
1088}
1089
1090struct file *dentry_open(const struct path *path, int flags,
1091 const struct cred *cred)
1092{
1093 int error;
1094 struct file *f;
1095
1096 /* We must always pass in a valid mount pointer. */
1097 BUG_ON(!path->mnt);
1098
1099 f = alloc_empty_file(flags, cred);
1100 if (!IS_ERR(f)) {
1101 error = vfs_open(path, f);
1102 if (error) {
1103 fput(f);
1104 f = ERR_PTR(error);
1105 }
1106 }
1107 return f;
1108}
1109EXPORT_SYMBOL(dentry_open);
1110
1111/**
1112 * dentry_create - Create and open a file
1113 * @path: path to create
1114 * @flags: O_ flags
1115 * @mode: mode bits for new file
1116 * @cred: credentials to use
1117 *
1118 * Caller must hold the parent directory's lock, and have prepared
1119 * a negative dentry, placed in @path->dentry, for the new file.
1120 *
1121 * Caller sets @path->mnt to the vfsmount of the filesystem where
1122 * the new file is to be created. The parent directory and the
1123 * negative dentry must reside on the same filesystem instance.
1124 *
1125 * On success, returns a "struct file *". Otherwise a ERR_PTR
1126 * is returned.
1127 */
1128struct file *dentry_create(const struct path *path, int flags, umode_t mode,
1129 const struct cred *cred)
1130{
1131 struct file *f;
1132 int error;
1133
1134 f = alloc_empty_file(flags, cred);
1135 if (IS_ERR(f))
1136 return f;
1137
1138 error = vfs_create(mnt_idmap(path->mnt),
1139 d_inode(path->dentry->d_parent),
1140 path->dentry, mode, true);
1141 if (!error)
1142 error = vfs_open(path, f);
1143
1144 if (unlikely(error)) {
1145 fput(f);
1146 return ERR_PTR(error);
1147 }
1148 return f;
1149}
1150EXPORT_SYMBOL(dentry_create);
1151
1152/**
1153 * kernel_file_open - open a file for kernel internal use
1154 * @path: path of the file to open
1155 * @flags: open flags
1156 * @inode: the inode
1157 * @cred: credentials for open
1158 *
1159 * Open a file for use by in-kernel consumers. The file is not accounted
1160 * against nr_files and must not be installed into the file descriptor
1161 * table.
1162 *
1163 * Return: Opened file on success, an error pointer on failure.
1164 */
1165struct file *kernel_file_open(const struct path *path, int flags,
1166 struct inode *inode, const struct cred *cred)
1167{
1168 struct file *f;
1169 int error;
1170
1171 f = alloc_empty_file_noaccount(flags, cred);
1172 if (IS_ERR(f))
1173 return f;
1174
1175 f->f_path = *path;
1176 error = do_dentry_open(f, inode, NULL);
1177 if (error) {
1178 fput(f);
1179 f = ERR_PTR(error);
1180 }
1181 return f;
1182}
1183EXPORT_SYMBOL_GPL(kernel_file_open);
1184
1185#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE))
1186#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
1187
1188inline struct open_how build_open_how(int flags, umode_t mode)
1189{
1190 struct open_how how = {
1191 .flags = flags & VALID_OPEN_FLAGS,
1192 .mode = mode & S_IALLUGO,
1193 };
1194
1195 /* O_PATH beats everything else. */
1196 if (how.flags & O_PATH)
1197 how.flags &= O_PATH_FLAGS;
1198 /* Modes should only be set for create-like flags. */
1199 if (!WILL_CREATE(how.flags))
1200 how.mode = 0;
1201 return how;
1202}
1203
1204inline int build_open_flags(const struct open_how *how, struct open_flags *op)
1205{
1206 u64 flags = how->flags;
1207 u64 strip = __FMODE_NONOTIFY | O_CLOEXEC;
1208 int lookup_flags = 0;
1209 int acc_mode = ACC_MODE(flags);
1210
1211 BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
1212 "struct open_flags doesn't yet handle flags > 32 bits");
1213
1214 /*
1215 * Strip flags that either shouldn't be set by userspace like
1216 * FMODE_NONOTIFY or that aren't relevant in determining struct
1217 * open_flags like O_CLOEXEC.
1218 */
1219 flags &= ~strip;
1220
1221 /*
1222 * Older syscalls implicitly clear all of the invalid flags or argument
1223 * values before calling build_open_flags(), but openat2(2) checks all
1224 * of its arguments.
1225 */
1226 if (flags & ~VALID_OPEN_FLAGS)
1227 return -EINVAL;
1228 if (how->resolve & ~VALID_RESOLVE_FLAGS)
1229 return -EINVAL;
1230
1231 /* Scoping flags are mutually exclusive. */
1232 if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
1233 return -EINVAL;
1234
1235 /* Deal with the mode. */
1236 if (WILL_CREATE(flags)) {
1237 if (how->mode & ~S_IALLUGO)
1238 return -EINVAL;
1239 op->mode = how->mode | S_IFREG;
1240 } else {
1241 if (how->mode != 0)
1242 return -EINVAL;
1243 op->mode = 0;
1244 }
1245
1246 /*
1247 * Block bugs where O_DIRECTORY | O_CREAT created regular files.
1248 * Note, that blocking O_DIRECTORY | O_CREAT here also protects
1249 * O_TMPFILE below which requires O_DIRECTORY being raised.
1250 */
1251 if ((flags & (O_DIRECTORY | O_CREAT)) == (O_DIRECTORY | O_CREAT))
1252 return -EINVAL;
1253
1254 /* Now handle the creative implementation of O_TMPFILE. */
1255 if (flags & __O_TMPFILE) {
1256 /*
1257 * In order to ensure programs get explicit errors when trying
1258 * to use O_TMPFILE on old kernels we enforce that O_DIRECTORY
1259 * is raised alongside __O_TMPFILE.
1260 */
1261 if (!(flags & O_DIRECTORY))
1262 return -EINVAL;
1263 if (!(acc_mode & MAY_WRITE))
1264 return -EINVAL;
1265 }
1266 if (flags & O_PATH) {
1267 /* O_PATH only permits certain other flags to be set. */
1268 if (flags & ~O_PATH_FLAGS)
1269 return -EINVAL;
1270 acc_mode = 0;
1271 }
1272
1273 /*
1274 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1275 * check for O_DSYNC if the need any syncing at all we enforce it's
1276 * always set instead of having to deal with possibly weird behaviour
1277 * for malicious applications setting only __O_SYNC.
1278 */
1279 if (flags & __O_SYNC)
1280 flags |= O_DSYNC;
1281
1282 op->open_flag = flags;
1283
1284 /* O_TRUNC implies we need access checks for write permissions */
1285 if (flags & O_TRUNC)
1286 acc_mode |= MAY_WRITE;
1287
1288 /* Allow the LSM permission hook to distinguish append
1289 access from general write access. */
1290 if (flags & O_APPEND)
1291 acc_mode |= MAY_APPEND;
1292
1293 op->acc_mode = acc_mode;
1294
1295 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1296
1297 if (flags & O_CREAT) {
1298 op->intent |= LOOKUP_CREATE;
1299 if (flags & O_EXCL) {
1300 op->intent |= LOOKUP_EXCL;
1301 flags |= O_NOFOLLOW;
1302 }
1303 }
1304
1305 if (flags & O_DIRECTORY)
1306 lookup_flags |= LOOKUP_DIRECTORY;
1307 if (!(flags & O_NOFOLLOW))
1308 lookup_flags |= LOOKUP_FOLLOW;
1309
1310 if (how->resolve & RESOLVE_NO_XDEV)
1311 lookup_flags |= LOOKUP_NO_XDEV;
1312 if (how->resolve & RESOLVE_NO_MAGICLINKS)
1313 lookup_flags |= LOOKUP_NO_MAGICLINKS;
1314 if (how->resolve & RESOLVE_NO_SYMLINKS)
1315 lookup_flags |= LOOKUP_NO_SYMLINKS;
1316 if (how->resolve & RESOLVE_BENEATH)
1317 lookup_flags |= LOOKUP_BENEATH;
1318 if (how->resolve & RESOLVE_IN_ROOT)
1319 lookup_flags |= LOOKUP_IN_ROOT;
1320 if (how->resolve & RESOLVE_CACHED) {
1321 /* Don't bother even trying for create/truncate/tmpfile open */
1322 if (flags & (O_TRUNC | O_CREAT | __O_TMPFILE))
1323 return -EAGAIN;
1324 lookup_flags |= LOOKUP_CACHED;
1325 }
1326
1327 op->lookup_flags = lookup_flags;
1328 return 0;
1329}
1330
1331/**
1332 * file_open_name - open file and return file pointer
1333 *
1334 * @name: struct filename containing path to open
1335 * @flags: open flags as per the open(2) second argument
1336 * @mode: mode for the new file if O_CREAT is set, else ignored
1337 *
1338 * This is the helper to open a file from kernelspace if you really
1339 * have to. But in generally you should not do this, so please move
1340 * along, nothing to see here..
1341 */
1342struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1343{
1344 struct open_flags op;
1345 struct open_how how = build_open_how(flags, mode);
1346 int err = build_open_flags(&how, &op);
1347 if (err)
1348 return ERR_PTR(err);
1349 return do_filp_open(AT_FDCWD, name, &op);
1350}
1351
1352/**
1353 * filp_open - open file and return file pointer
1354 *
1355 * @filename: path to open
1356 * @flags: open flags as per the open(2) second argument
1357 * @mode: mode for the new file if O_CREAT is set, else ignored
1358 *
1359 * This is the helper to open a file from kernelspace if you really
1360 * have to. But in generally you should not do this, so please move
1361 * along, nothing to see here..
1362 */
1363struct file *filp_open(const char *filename, int flags, umode_t mode)
1364{
1365 struct filename *name = getname_kernel(filename);
1366 struct file *file = ERR_CAST(name);
1367
1368 if (!IS_ERR(name)) {
1369 file = file_open_name(name, flags, mode);
1370 putname(name);
1371 }
1372 return file;
1373}
1374EXPORT_SYMBOL(filp_open);
1375
1376struct file *file_open_root(const struct path *root,
1377 const char *filename, int flags, umode_t mode)
1378{
1379 struct open_flags op;
1380 struct open_how how = build_open_how(flags, mode);
1381 int err = build_open_flags(&how, &op);
1382 if (err)
1383 return ERR_PTR(err);
1384 return do_file_open_root(root, filename, &op);
1385}
1386EXPORT_SYMBOL(file_open_root);
1387
1388static long do_sys_openat2(int dfd, const char __user *filename,
1389 struct open_how *how)
1390{
1391 struct open_flags op;
1392 int fd = build_open_flags(how, &op);
1393 struct filename *tmp;
1394
1395 if (fd)
1396 return fd;
1397
1398 tmp = getname(filename);
1399 if (IS_ERR(tmp))
1400 return PTR_ERR(tmp);
1401
1402 fd = get_unused_fd_flags(how->flags);
1403 if (fd >= 0) {
1404 struct file *f = do_filp_open(dfd, tmp, &op);
1405 if (IS_ERR(f)) {
1406 put_unused_fd(fd);
1407 fd = PTR_ERR(f);
1408 } else {
1409 fd_install(fd, f);
1410 }
1411 }
1412 putname(tmp);
1413 return fd;
1414}
1415
1416long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1417{
1418 struct open_how how = build_open_how(flags, mode);
1419 return do_sys_openat2(dfd, filename, &how);
1420}
1421
1422
1423SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1424{
1425 if (force_o_largefile())
1426 flags |= O_LARGEFILE;
1427 return do_sys_open(AT_FDCWD, filename, flags, mode);
1428}
1429
1430SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1431 umode_t, mode)
1432{
1433 if (force_o_largefile())
1434 flags |= O_LARGEFILE;
1435 return do_sys_open(dfd, filename, flags, mode);
1436}
1437
1438SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1439 struct open_how __user *, how, size_t, usize)
1440{
1441 int err;
1442 struct open_how tmp;
1443
1444 BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1445 BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1446
1447 if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1448 return -EINVAL;
1449
1450 err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
1451 if (err)
1452 return err;
1453
1454 audit_openat2_how(&tmp);
1455
1456 /* O_LARGEFILE is only allowed for non-O_PATH. */
1457 if (!(tmp.flags & O_PATH) && force_o_largefile())
1458 tmp.flags |= O_LARGEFILE;
1459
1460 return do_sys_openat2(dfd, filename, &tmp);
1461}
1462
1463#ifdef CONFIG_COMPAT
1464/*
1465 * Exactly like sys_open(), except that it doesn't set the
1466 * O_LARGEFILE flag.
1467 */
1468COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1469{
1470 return do_sys_open(AT_FDCWD, filename, flags, mode);
1471}
1472
1473/*
1474 * Exactly like sys_openat(), except that it doesn't set the
1475 * O_LARGEFILE flag.
1476 */
1477COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1478{
1479 return do_sys_open(dfd, filename, flags, mode);
1480}
1481#endif
1482
1483#ifndef __alpha__
1484
1485/*
1486 * For backward compatibility? Maybe this should be moved
1487 * into arch/i386 instead?
1488 */
1489SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1490{
1491 int flags = O_CREAT | O_WRONLY | O_TRUNC;
1492
1493 if (force_o_largefile())
1494 flags |= O_LARGEFILE;
1495 return do_sys_open(AT_FDCWD, pathname, flags, mode);
1496}
1497#endif
1498
1499/*
1500 * "id" is the POSIX thread ID. We use the
1501 * files pointer for this..
1502 */
1503static int filp_flush(struct file *filp, fl_owner_t id)
1504{
1505 int retval = 0;
1506
1507 if (CHECK_DATA_CORRUPTION(file_count(filp) == 0,
1508 "VFS: Close: file count is 0 (f_op=%ps)",
1509 filp->f_op)) {
1510 return 0;
1511 }
1512
1513 if (filp->f_op->flush)
1514 retval = filp->f_op->flush(filp, id);
1515
1516 if (likely(!(filp->f_mode & FMODE_PATH))) {
1517 dnotify_flush(filp, id);
1518 locks_remove_posix(filp, id);
1519 }
1520 return retval;
1521}
1522
1523int filp_close(struct file *filp, fl_owner_t id)
1524{
1525 int retval;
1526
1527 retval = filp_flush(filp, id);
1528 fput(filp);
1529
1530 return retval;
1531}
1532EXPORT_SYMBOL(filp_close);
1533
1534/*
1535 * Careful here! We test whether the file pointer is NULL before
1536 * releasing the fd. This ensures that one clone task can't release
1537 * an fd while another clone is opening it.
1538 */
1539SYSCALL_DEFINE1(close, unsigned int, fd)
1540{
1541 int retval;
1542 struct file *file;
1543
1544 file = file_close_fd(fd);
1545 if (!file)
1546 return -EBADF;
1547
1548 retval = filp_flush(file, current->files);
1549
1550 /*
1551 * We're returning to user space. Don't bother
1552 * with any delayed fput() cases.
1553 */
1554 __fput_sync(file);
1555
1556 /* can't restart close syscall because file table entry was cleared */
1557 if (unlikely(retval == -ERESTARTSYS ||
1558 retval == -ERESTARTNOINTR ||
1559 retval == -ERESTARTNOHAND ||
1560 retval == -ERESTART_RESTARTBLOCK))
1561 retval = -EINTR;
1562
1563 return retval;
1564}
1565
1566/**
1567 * sys_close_range() - Close all file descriptors in a given range.
1568 *
1569 * @fd: starting file descriptor to close
1570 * @max_fd: last file descriptor to close
1571 * @flags: reserved for future extensions
1572 *
1573 * This closes a range of file descriptors. All file descriptors
1574 * from @fd up to and including @max_fd are closed.
1575 * Currently, errors to close a given file descriptor are ignored.
1576 */
1577SYSCALL_DEFINE3(close_range, unsigned int, fd, unsigned int, max_fd,
1578 unsigned int, flags)
1579{
1580 return __close_range(fd, max_fd, flags);
1581}
1582
1583/*
1584 * This routine simulates a hangup on the tty, to arrange that users
1585 * are given clean terminals at login time.
1586 */
1587SYSCALL_DEFINE0(vhangup)
1588{
1589 if (capable(CAP_SYS_TTY_CONFIG)) {
1590 tty_vhangup_self();
1591 return 0;
1592 }
1593 return -EPERM;
1594}
1595
1596/*
1597 * Called when an inode is about to be open.
1598 * We use this to disallow opening large files on 32bit systems if
1599 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1600 * on this flag in sys_open.
1601 */
1602int generic_file_open(struct inode * inode, struct file * filp)
1603{
1604 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1605 return -EOVERFLOW;
1606 return 0;
1607}
1608
1609EXPORT_SYMBOL(generic_file_open);
1610
1611/*
1612 * This is used by subsystems that don't want seekable
1613 * file descriptors. The function is not supposed to ever fail, the only
1614 * reason it returns an 'int' and not 'void' is so that it can be plugged
1615 * directly into file_operations structure.
1616 */
1617int nonseekable_open(struct inode *inode, struct file *filp)
1618{
1619 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1620 return 0;
1621}
1622
1623EXPORT_SYMBOL(nonseekable_open);
1624
1625/*
1626 * stream_open is used by subsystems that want stream-like file descriptors.
1627 * Such file descriptors are not seekable and don't have notion of position
1628 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1629 * Contrary to file descriptors of other regular files, .read() and .write()
1630 * can run simultaneously.
1631 *
1632 * stream_open never fails and is marked to return int so that it could be
1633 * directly used as file_operations.open .
1634 */
1635int stream_open(struct inode *inode, struct file *filp)
1636{
1637 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1638 filp->f_mode |= FMODE_STREAM;
1639 return 0;
1640}
1641
1642EXPORT_SYMBOL(stream_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 dentry *dentry, loff_t length, unsigned int time_attrs,
39 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(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 inode *inode;
72 long error;
73
74 inode = path->dentry->d_inode;
75
76 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
77 if (S_ISDIR(inode->i_mode))
78 return -EISDIR;
79 if (!S_ISREG(inode->i_mode))
80 return -EINVAL;
81
82 error = mnt_want_write(path->mnt);
83 if (error)
84 goto out;
85
86 error = inode_permission(inode, MAY_WRITE);
87 if (error)
88 goto mnt_drop_write_and_out;
89
90 error = -EPERM;
91 if (IS_APPEND(inode))
92 goto mnt_drop_write_and_out;
93
94 error = get_write_access(inode);
95 if (error)
96 goto mnt_drop_write_and_out;
97
98 /*
99 * Make sure that there are no leases. get_write_access() protects
100 * against the truncate racing with a lease-granting setlease().
101 */
102 error = break_lease(inode, O_WRONLY);
103 if (error)
104 goto put_write_and_out;
105
106 error = locks_verify_truncate(inode, NULL, length);
107 if (!error)
108 error = security_path_truncate(path);
109 if (!error)
110 error = do_truncate(path->dentry, length, 0, NULL);
111
112put_write_and_out:
113 put_write_access(inode);
114mnt_drop_write_and_out:
115 mnt_drop_write(path->mnt);
116out:
117 return error;
118}
119EXPORT_SYMBOL_GPL(vfs_truncate);
120
121long do_sys_truncate(const char __user *pathname, loff_t length)
122{
123 unsigned int lookup_flags = LOOKUP_FOLLOW;
124 struct path path;
125 int error;
126
127 if (length < 0) /* sorry, but loff_t says... */
128 return -EINVAL;
129
130retry:
131 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
132 if (!error) {
133 error = vfs_truncate(&path, length);
134 path_put(&path);
135 }
136 if (retry_estale(error, lookup_flags)) {
137 lookup_flags |= LOOKUP_REVAL;
138 goto retry;
139 }
140 return error;
141}
142
143SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
144{
145 return do_sys_truncate(path, length);
146}
147
148#ifdef CONFIG_COMPAT
149COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
150{
151 return do_sys_truncate(path, length);
152}
153#endif
154
155long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
156{
157 struct inode *inode;
158 struct dentry *dentry;
159 struct fd f;
160 int error;
161
162 error = -EINVAL;
163 if (length < 0)
164 goto out;
165 error = -EBADF;
166 f = fdget(fd);
167 if (!f.file)
168 goto out;
169
170 /* explicitly opened as large or we are on 64-bit box */
171 if (f.file->f_flags & O_LARGEFILE)
172 small = 0;
173
174 dentry = f.file->f_path.dentry;
175 inode = dentry->d_inode;
176 error = -EINVAL;
177 if (!S_ISREG(inode->i_mode) || !(f.file->f_mode & FMODE_WRITE))
178 goto out_putf;
179
180 error = -EINVAL;
181 /* Cannot ftruncate over 2^31 bytes without large file support */
182 if (small && length > MAX_NON_LFS)
183 goto out_putf;
184
185 error = -EPERM;
186 /* Check IS_APPEND on real upper inode */
187 if (IS_APPEND(file_inode(f.file)))
188 goto out_putf;
189
190 sb_start_write(inode->i_sb);
191 error = locks_verify_truncate(inode, f.file, length);
192 if (!error)
193 error = security_path_truncate(&f.file->f_path);
194 if (!error)
195 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, f.file);
196 sb_end_write(inode->i_sb);
197out_putf:
198 fdput(f);
199out:
200 return error;
201}
202
203SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length)
204{
205 return do_sys_ftruncate(fd, length, 1);
206}
207
208#ifdef CONFIG_COMPAT
209COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_ulong_t, length)
210{
211 return do_sys_ftruncate(fd, length, 1);
212}
213#endif
214
215/* LFS versions of truncate are only needed on 32 bit machines */
216#if BITS_PER_LONG == 32
217SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
218{
219 return do_sys_truncate(path, length);
220}
221
222SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
223{
224 return do_sys_ftruncate(fd, length, 0);
225}
226#endif /* BITS_PER_LONG == 32 */
227
228
229int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
230{
231 struct inode *inode = file_inode(file);
232 long ret;
233
234 if (offset < 0 || len <= 0)
235 return -EINVAL;
236
237 /* Return error if mode is not supported */
238 if (mode & ~FALLOC_FL_SUPPORTED_MASK)
239 return -EOPNOTSUPP;
240
241 /* Punch hole and zero range are mutually exclusive */
242 if ((mode & (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE)) ==
243 (FALLOC_FL_PUNCH_HOLE | FALLOC_FL_ZERO_RANGE))
244 return -EOPNOTSUPP;
245
246 /* Punch hole must have keep size set */
247 if ((mode & FALLOC_FL_PUNCH_HOLE) &&
248 !(mode & FALLOC_FL_KEEP_SIZE))
249 return -EOPNOTSUPP;
250
251 /* Collapse range should only be used exclusively. */
252 if ((mode & FALLOC_FL_COLLAPSE_RANGE) &&
253 (mode & ~FALLOC_FL_COLLAPSE_RANGE))
254 return -EINVAL;
255
256 /* Insert range should only be used exclusively. */
257 if ((mode & FALLOC_FL_INSERT_RANGE) &&
258 (mode & ~FALLOC_FL_INSERT_RANGE))
259 return -EINVAL;
260
261 /* Unshare range should only be used with allocate mode. */
262 if ((mode & FALLOC_FL_UNSHARE_RANGE) &&
263 (mode & ~(FALLOC_FL_UNSHARE_RANGE | FALLOC_FL_KEEP_SIZE)))
264 return -EINVAL;
265
266 if (!(file->f_mode & FMODE_WRITE))
267 return -EBADF;
268
269 /*
270 * We can only allow pure fallocate on append only files
271 */
272 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
273 return -EPERM;
274
275 if (IS_IMMUTABLE(inode))
276 return -EPERM;
277
278 /*
279 * We cannot allow any fallocate operation on an active swapfile
280 */
281 if (IS_SWAPFILE(inode))
282 return -ETXTBSY;
283
284 /*
285 * Revalidate the write permissions, in case security policy has
286 * changed since the files were opened.
287 */
288 ret = security_file_permission(file, MAY_WRITE);
289 if (ret)
290 return ret;
291
292 if (S_ISFIFO(inode->i_mode))
293 return -ESPIPE;
294
295 if (S_ISDIR(inode->i_mode))
296 return -EISDIR;
297
298 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
299 return -ENODEV;
300
301 /* Check for wrap through zero too */
302 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
303 return -EFBIG;
304
305 if (!file->f_op->fallocate)
306 return -EOPNOTSUPP;
307
308 file_start_write(file);
309 ret = file->f_op->fallocate(file, mode, offset, len);
310
311 /*
312 * Create inotify and fanotify events.
313 *
314 * To keep the logic simple always create events if fallocate succeeds.
315 * This implies that events are even created if the file size remains
316 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
317 */
318 if (ret == 0)
319 fsnotify_modify(file);
320
321 file_end_write(file);
322 return ret;
323}
324EXPORT_SYMBOL_GPL(vfs_fallocate);
325
326int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
327{
328 struct fd f = fdget(fd);
329 int error = -EBADF;
330
331 if (f.file) {
332 error = vfs_fallocate(f.file, mode, offset, len);
333 fdput(f);
334 }
335 return error;
336}
337
338SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
339{
340 return ksys_fallocate(fd, mode, offset, len);
341}
342
343/*
344 * access() needs to use the real uid/gid, not the effective uid/gid.
345 * We do this by temporarily clearing all FS-related capabilities and
346 * switching the fsuid/fsgid around to the real ones.
347 */
348long do_faccessat(int dfd, const char __user *filename, int mode)
349{
350 const struct cred *old_cred;
351 struct cred *override_cred;
352 struct path path;
353 struct inode *inode;
354 int res;
355 unsigned int lookup_flags = LOOKUP_FOLLOW;
356
357 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
358 return -EINVAL;
359
360 override_cred = prepare_creds();
361 if (!override_cred)
362 return -ENOMEM;
363
364 override_cred->fsuid = override_cred->uid;
365 override_cred->fsgid = override_cred->gid;
366
367 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
368 /* Clear the capabilities if we switch to a non-root user */
369 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
370 if (!uid_eq(override_cred->uid, root_uid))
371 cap_clear(override_cred->cap_effective);
372 else
373 override_cred->cap_effective =
374 override_cred->cap_permitted;
375 }
376
377 /*
378 * The new set of credentials can *only* be used in
379 * task-synchronous circumstances, and does not need
380 * RCU freeing, unless somebody then takes a separate
381 * reference to it.
382 *
383 * NOTE! This is _only_ true because this credential
384 * is used purely for override_creds() that installs
385 * it as the subjective cred. Other threads will be
386 * accessing ->real_cred, not the subjective cred.
387 *
388 * If somebody _does_ make a copy of this (using the
389 * 'get_current_cred()' function), that will clear the
390 * non_rcu field, because now that other user may be
391 * expecting RCU freeing. But normal thread-synchronous
392 * cred accesses will keep things non-RCY.
393 */
394 override_cred->non_rcu = 1;
395
396 old_cred = override_creds(override_cred);
397retry:
398 res = user_path_at(dfd, filename, lookup_flags, &path);
399 if (res)
400 goto out;
401
402 inode = d_backing_inode(path.dentry);
403
404 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
405 /*
406 * MAY_EXEC on regular files is denied if the fs is mounted
407 * with the "noexec" flag.
408 */
409 res = -EACCES;
410 if (path_noexec(&path))
411 goto out_path_release;
412 }
413
414 res = inode_permission(inode, mode | MAY_ACCESS);
415 /* SuS v2 requires we report a read only fs too */
416 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
417 goto out_path_release;
418 /*
419 * This is a rare case where using __mnt_is_readonly()
420 * is OK without a mnt_want/drop_write() pair. Since
421 * no actual write to the fs is performed here, we do
422 * not need to telegraph to that to anyone.
423 *
424 * By doing this, we accept that this access is
425 * inherently racy and know that the fs may change
426 * state before we even see this result.
427 */
428 if (__mnt_is_readonly(path.mnt))
429 res = -EROFS;
430
431out_path_release:
432 path_put(&path);
433 if (retry_estale(res, lookup_flags)) {
434 lookup_flags |= LOOKUP_REVAL;
435 goto retry;
436 }
437out:
438 revert_creds(old_cred);
439 put_cred(override_cred);
440 return res;
441}
442
443SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
444{
445 return do_faccessat(dfd, filename, mode);
446}
447
448SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
449{
450 return do_faccessat(AT_FDCWD, filename, mode);
451}
452
453int ksys_chdir(const char __user *filename)
454{
455 struct path path;
456 int error;
457 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
458retry:
459 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
460 if (error)
461 goto out;
462
463 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
464 if (error)
465 goto dput_and_out;
466
467 set_fs_pwd(current->fs, &path);
468
469dput_and_out:
470 path_put(&path);
471 if (retry_estale(error, lookup_flags)) {
472 lookup_flags |= LOOKUP_REVAL;
473 goto retry;
474 }
475out:
476 return error;
477}
478
479SYSCALL_DEFINE1(chdir, const char __user *, filename)
480{
481 return ksys_chdir(filename);
482}
483
484SYSCALL_DEFINE1(fchdir, unsigned int, fd)
485{
486 struct fd f = fdget_raw(fd);
487 int error;
488
489 error = -EBADF;
490 if (!f.file)
491 goto out;
492
493 error = -ENOTDIR;
494 if (!d_can_lookup(f.file->f_path.dentry))
495 goto out_putf;
496
497 error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
498 if (!error)
499 set_fs_pwd(current->fs, &f.file->f_path);
500out_putf:
501 fdput(f);
502out:
503 return error;
504}
505
506int ksys_chroot(const char __user *filename)
507{
508 struct path path;
509 int error;
510 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
511retry:
512 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
513 if (error)
514 goto out;
515
516 error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
517 if (error)
518 goto dput_and_out;
519
520 error = -EPERM;
521 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
522 goto dput_and_out;
523 error = security_path_chroot(&path);
524 if (error)
525 goto dput_and_out;
526
527 set_fs_root(current->fs, &path);
528 error = 0;
529dput_and_out:
530 path_put(&path);
531 if (retry_estale(error, lookup_flags)) {
532 lookup_flags |= LOOKUP_REVAL;
533 goto retry;
534 }
535out:
536 return error;
537}
538
539SYSCALL_DEFINE1(chroot, const char __user *, filename)
540{
541 return ksys_chroot(filename);
542}
543
544static int chmod_common(const struct path *path, umode_t mode)
545{
546 struct inode *inode = path->dentry->d_inode;
547 struct inode *delegated_inode = NULL;
548 struct iattr newattrs;
549 int error;
550
551 error = mnt_want_write(path->mnt);
552 if (error)
553 return error;
554retry_deleg:
555 inode_lock(inode);
556 error = security_path_chmod(path, mode);
557 if (error)
558 goto out_unlock;
559 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
560 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
561 error = notify_change(path->dentry, &newattrs, &delegated_inode);
562out_unlock:
563 inode_unlock(inode);
564 if (delegated_inode) {
565 error = break_deleg_wait(&delegated_inode);
566 if (!error)
567 goto retry_deleg;
568 }
569 mnt_drop_write(path->mnt);
570 return error;
571}
572
573int ksys_fchmod(unsigned int fd, umode_t mode)
574{
575 struct fd f = fdget(fd);
576 int err = -EBADF;
577
578 if (f.file) {
579 audit_file(f.file);
580 err = chmod_common(&f.file->f_path, mode);
581 fdput(f);
582 }
583 return err;
584}
585
586SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
587{
588 return ksys_fchmod(fd, mode);
589}
590
591int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
592{
593 struct path path;
594 int error;
595 unsigned int lookup_flags = LOOKUP_FOLLOW;
596retry:
597 error = user_path_at(dfd, filename, lookup_flags, &path);
598 if (!error) {
599 error = chmod_common(&path, mode);
600 path_put(&path);
601 if (retry_estale(error, lookup_flags)) {
602 lookup_flags |= LOOKUP_REVAL;
603 goto retry;
604 }
605 }
606 return error;
607}
608
609SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
610 umode_t, mode)
611{
612 return do_fchmodat(dfd, filename, mode);
613}
614
615SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
616{
617 return do_fchmodat(AT_FDCWD, filename, mode);
618}
619
620static int chown_common(const struct path *path, uid_t user, gid_t group)
621{
622 struct inode *inode = path->dentry->d_inode;
623 struct inode *delegated_inode = NULL;
624 int error;
625 struct iattr newattrs;
626 kuid_t uid;
627 kgid_t gid;
628
629 uid = make_kuid(current_user_ns(), user);
630 gid = make_kgid(current_user_ns(), group);
631
632retry_deleg:
633 newattrs.ia_valid = ATTR_CTIME;
634 if (user != (uid_t) -1) {
635 if (!uid_valid(uid))
636 return -EINVAL;
637 newattrs.ia_valid |= ATTR_UID;
638 newattrs.ia_uid = uid;
639 }
640 if (group != (gid_t) -1) {
641 if (!gid_valid(gid))
642 return -EINVAL;
643 newattrs.ia_valid |= ATTR_GID;
644 newattrs.ia_gid = gid;
645 }
646 if (!S_ISDIR(inode->i_mode))
647 newattrs.ia_valid |=
648 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
649 inode_lock(inode);
650 error = security_path_chown(path, uid, gid);
651 if (!error)
652 error = notify_change(path->dentry, &newattrs, &delegated_inode);
653 inode_unlock(inode);
654 if (delegated_inode) {
655 error = break_deleg_wait(&delegated_inode);
656 if (!error)
657 goto retry_deleg;
658 }
659 return error;
660}
661
662int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
663 int flag)
664{
665 struct path path;
666 int error = -EINVAL;
667 int lookup_flags;
668
669 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
670 goto out;
671
672 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
673 if (flag & AT_EMPTY_PATH)
674 lookup_flags |= LOOKUP_EMPTY;
675retry:
676 error = user_path_at(dfd, filename, lookup_flags, &path);
677 if (error)
678 goto out;
679 error = mnt_want_write(path.mnt);
680 if (error)
681 goto out_release;
682 error = chown_common(&path, user, group);
683 mnt_drop_write(path.mnt);
684out_release:
685 path_put(&path);
686 if (retry_estale(error, lookup_flags)) {
687 lookup_flags |= LOOKUP_REVAL;
688 goto retry;
689 }
690out:
691 return error;
692}
693
694SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
695 gid_t, group, int, flag)
696{
697 return do_fchownat(dfd, filename, user, group, flag);
698}
699
700SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
701{
702 return do_fchownat(AT_FDCWD, filename, user, group, 0);
703}
704
705SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
706{
707 return do_fchownat(AT_FDCWD, filename, user, group,
708 AT_SYMLINK_NOFOLLOW);
709}
710
711int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
712{
713 struct fd f = fdget(fd);
714 int error = -EBADF;
715
716 if (!f.file)
717 goto out;
718
719 error = mnt_want_write_file(f.file);
720 if (error)
721 goto out_fput;
722 audit_file(f.file);
723 error = chown_common(&f.file->f_path, user, group);
724 mnt_drop_write_file(f.file);
725out_fput:
726 fdput(f);
727out:
728 return error;
729}
730
731SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
732{
733 return ksys_fchown(fd, user, group);
734}
735
736static int do_dentry_open(struct file *f,
737 struct inode *inode,
738 int (*open)(struct inode *, struct file *))
739{
740 static const struct file_operations empty_fops = {};
741 int error;
742
743 path_get(&f->f_path);
744 f->f_inode = inode;
745 f->f_mapping = inode->i_mapping;
746
747 /* Ensure that we skip any errors that predate opening of the file */
748 f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
749
750 if (unlikely(f->f_flags & O_PATH)) {
751 f->f_mode = FMODE_PATH | FMODE_OPENED;
752 f->f_op = &empty_fops;
753 return 0;
754 }
755
756 /* Any file opened for execve()/uselib() has to be a regular file. */
757 if (unlikely(f->f_flags & FMODE_EXEC && !S_ISREG(inode->i_mode))) {
758 error = -EACCES;
759 goto cleanup_file;
760 }
761
762 if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
763 error = get_write_access(inode);
764 if (unlikely(error))
765 goto cleanup_file;
766 error = __mnt_want_write(f->f_path.mnt);
767 if (unlikely(error)) {
768 put_write_access(inode);
769 goto cleanup_file;
770 }
771 f->f_mode |= FMODE_WRITER;
772 }
773
774 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
775 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
776 f->f_mode |= FMODE_ATOMIC_POS;
777
778 f->f_op = fops_get(inode->i_fop);
779 if (WARN_ON(!f->f_op)) {
780 error = -ENODEV;
781 goto cleanup_all;
782 }
783
784 error = security_file_open(f);
785 if (error)
786 goto cleanup_all;
787
788 error = break_lease(locks_inode(f), f->f_flags);
789 if (error)
790 goto cleanup_all;
791
792 /* normally all 3 are set; ->open() can clear them if needed */
793 f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
794 if (!open)
795 open = f->f_op->open;
796 if (open) {
797 error = open(inode, f);
798 if (error)
799 goto cleanup_all;
800 }
801 f->f_mode |= FMODE_OPENED;
802 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
803 i_readcount_inc(inode);
804 if ((f->f_mode & FMODE_READ) &&
805 likely(f->f_op->read || f->f_op->read_iter))
806 f->f_mode |= FMODE_CAN_READ;
807 if ((f->f_mode & FMODE_WRITE) &&
808 likely(f->f_op->write || f->f_op->write_iter))
809 f->f_mode |= FMODE_CAN_WRITE;
810
811 f->f_write_hint = WRITE_LIFE_NOT_SET;
812 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
813
814 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
815
816 /* NB: we're sure to have correct a_ops only after f_op->open */
817 if (f->f_flags & O_DIRECT) {
818 if (!f->f_mapping->a_ops || !f->f_mapping->a_ops->direct_IO)
819 return -EINVAL;
820 }
821
822 /*
823 * XXX: Huge page cache doesn't support writing yet. Drop all page
824 * cache for this file before processing writes.
825 */
826 if ((f->f_mode & FMODE_WRITE) && filemap_nr_thps(inode->i_mapping))
827 truncate_pagecache(inode, 0);
828
829 return 0;
830
831cleanup_all:
832 if (WARN_ON_ONCE(error > 0))
833 error = -EINVAL;
834 fops_put(f->f_op);
835 if (f->f_mode & FMODE_WRITER) {
836 put_write_access(inode);
837 __mnt_drop_write(f->f_path.mnt);
838 }
839cleanup_file:
840 path_put(&f->f_path);
841 f->f_path.mnt = NULL;
842 f->f_path.dentry = NULL;
843 f->f_inode = NULL;
844 return error;
845}
846
847/**
848 * finish_open - finish opening a file
849 * @file: file pointer
850 * @dentry: pointer to dentry
851 * @open: open callback
852 * @opened: state of open
853 *
854 * This can be used to finish opening a file passed to i_op->atomic_open().
855 *
856 * If the open callback is set to NULL, then the standard f_op->open()
857 * filesystem callback is substituted.
858 *
859 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
860 * the return value of d_splice_alias(), then the caller needs to perform dput()
861 * on it after finish_open().
862 *
863 * On successful return @file is a fully instantiated open file. After this, if
864 * an error occurs in ->atomic_open(), it needs to clean up with fput().
865 *
866 * Returns zero on success or -errno if the open failed.
867 */
868int finish_open(struct file *file, struct dentry *dentry,
869 int (*open)(struct inode *, struct file *))
870{
871 BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
872
873 file->f_path.dentry = dentry;
874 return do_dentry_open(file, d_backing_inode(dentry), open);
875}
876EXPORT_SYMBOL(finish_open);
877
878/**
879 * finish_no_open - finish ->atomic_open() without opening the file
880 *
881 * @file: file pointer
882 * @dentry: dentry or NULL (as returned from ->lookup())
883 *
884 * This can be used to set the result of a successful lookup in ->atomic_open().
885 *
886 * NB: unlike finish_open() this function does consume the dentry reference and
887 * the caller need not dput() it.
888 *
889 * Returns "0" which must be the return value of ->atomic_open() after having
890 * called this function.
891 */
892int finish_no_open(struct file *file, struct dentry *dentry)
893{
894 file->f_path.dentry = dentry;
895 return 0;
896}
897EXPORT_SYMBOL(finish_no_open);
898
899char *file_path(struct file *filp, char *buf, int buflen)
900{
901 return d_path(&filp->f_path, buf, buflen);
902}
903EXPORT_SYMBOL(file_path);
904
905/**
906 * vfs_open - open the file at the given path
907 * @path: path to open
908 * @file: newly allocated file with f_flag initialized
909 * @cred: credentials to use
910 */
911int vfs_open(const struct path *path, struct file *file)
912{
913 file->f_path = *path;
914 return do_dentry_open(file, d_backing_inode(path->dentry), NULL);
915}
916
917struct file *dentry_open(const struct path *path, int flags,
918 const struct cred *cred)
919{
920 int error;
921 struct file *f;
922
923 validate_creds(cred);
924
925 /* We must always pass in a valid mount pointer. */
926 BUG_ON(!path->mnt);
927
928 f = alloc_empty_file(flags, cred);
929 if (!IS_ERR(f)) {
930 error = vfs_open(path, f);
931 if (error) {
932 fput(f);
933 f = ERR_PTR(error);
934 }
935 }
936 return f;
937}
938EXPORT_SYMBOL(dentry_open);
939
940struct file *open_with_fake_path(const struct path *path, int flags,
941 struct inode *inode, const struct cred *cred)
942{
943 struct file *f = alloc_empty_file_noaccount(flags, cred);
944 if (!IS_ERR(f)) {
945 int error;
946
947 f->f_path = *path;
948 error = do_dentry_open(f, inode, NULL);
949 if (error) {
950 fput(f);
951 f = ERR_PTR(error);
952 }
953 }
954 return f;
955}
956EXPORT_SYMBOL(open_with_fake_path);
957
958static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op)
959{
960 int lookup_flags = 0;
961 int acc_mode = ACC_MODE(flags);
962
963 /*
964 * Clear out all open flags we don't know about so that we don't report
965 * them in fcntl(F_GETFD) or similar interfaces.
966 */
967 flags &= VALID_OPEN_FLAGS;
968
969 if (flags & (O_CREAT | __O_TMPFILE))
970 op->mode = (mode & S_IALLUGO) | S_IFREG;
971 else
972 op->mode = 0;
973
974 /* Must never be set by userspace */
975 flags &= ~FMODE_NONOTIFY & ~O_CLOEXEC;
976
977 /*
978 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
979 * check for O_DSYNC if the need any syncing at all we enforce it's
980 * always set instead of having to deal with possibly weird behaviour
981 * for malicious applications setting only __O_SYNC.
982 */
983 if (flags & __O_SYNC)
984 flags |= O_DSYNC;
985
986 if (flags & __O_TMPFILE) {
987 if ((flags & O_TMPFILE_MASK) != O_TMPFILE)
988 return -EINVAL;
989 if (!(acc_mode & MAY_WRITE))
990 return -EINVAL;
991 } else if (flags & O_PATH) {
992 /*
993 * If we have O_PATH in the open flag. Then we
994 * cannot have anything other than the below set of flags
995 */
996 flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH;
997 acc_mode = 0;
998 }
999
1000 op->open_flag = flags;
1001
1002 /* O_TRUNC implies we need access checks for write permissions */
1003 if (flags & O_TRUNC)
1004 acc_mode |= MAY_WRITE;
1005
1006 /* Allow the LSM permission hook to distinguish append
1007 access from general write access. */
1008 if (flags & O_APPEND)
1009 acc_mode |= MAY_APPEND;
1010
1011 op->acc_mode = acc_mode;
1012
1013 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1014
1015 if (flags & O_CREAT) {
1016 op->intent |= LOOKUP_CREATE;
1017 if (flags & O_EXCL)
1018 op->intent |= LOOKUP_EXCL;
1019 }
1020
1021 if (flags & O_DIRECTORY)
1022 lookup_flags |= LOOKUP_DIRECTORY;
1023 if (!(flags & O_NOFOLLOW))
1024 lookup_flags |= LOOKUP_FOLLOW;
1025 op->lookup_flags = lookup_flags;
1026 return 0;
1027}
1028
1029/**
1030 * file_open_name - open file and return file pointer
1031 *
1032 * @name: struct filename containing path to open
1033 * @flags: open flags as per the open(2) second argument
1034 * @mode: mode for the new file if O_CREAT is set, else ignored
1035 *
1036 * This is the helper to open a file from kernelspace if you really
1037 * have to. But in generally you should not do this, so please move
1038 * along, nothing to see here..
1039 */
1040struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1041{
1042 struct open_flags op;
1043 int err = build_open_flags(flags, mode, &op);
1044 return err ? ERR_PTR(err) : do_filp_open(AT_FDCWD, name, &op);
1045}
1046
1047/**
1048 * filp_open - open file and return file pointer
1049 *
1050 * @filename: path to open
1051 * @flags: open flags as per the open(2) second argument
1052 * @mode: mode for the new file if O_CREAT is set, else ignored
1053 *
1054 * This is the helper to open a file from kernelspace if you really
1055 * have to. But in generally you should not do this, so please move
1056 * along, nothing to see here..
1057 */
1058struct file *filp_open(const char *filename, int flags, umode_t mode)
1059{
1060 struct filename *name = getname_kernel(filename);
1061 struct file *file = ERR_CAST(name);
1062
1063 if (!IS_ERR(name)) {
1064 file = file_open_name(name, flags, mode);
1065 putname(name);
1066 }
1067 return file;
1068}
1069EXPORT_SYMBOL(filp_open);
1070
1071struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt,
1072 const char *filename, int flags, umode_t mode)
1073{
1074 struct open_flags op;
1075 int err = build_open_flags(flags, mode, &op);
1076 if (err)
1077 return ERR_PTR(err);
1078 return do_file_open_root(dentry, mnt, filename, &op);
1079}
1080EXPORT_SYMBOL(file_open_root);
1081
1082long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1083{
1084 struct open_flags op;
1085 int fd = build_open_flags(flags, mode, &op);
1086 struct filename *tmp;
1087
1088 if (fd)
1089 return fd;
1090
1091 tmp = getname(filename);
1092 if (IS_ERR(tmp))
1093 return PTR_ERR(tmp);
1094
1095 fd = get_unused_fd_flags(flags);
1096 if (fd >= 0) {
1097 struct file *f = do_filp_open(dfd, tmp, &op);
1098 if (IS_ERR(f)) {
1099 put_unused_fd(fd);
1100 fd = PTR_ERR(f);
1101 } else {
1102 fsnotify_open(f);
1103 fd_install(fd, f);
1104 }
1105 }
1106 putname(tmp);
1107 return fd;
1108}
1109
1110SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1111{
1112 if (force_o_largefile())
1113 flags |= O_LARGEFILE;
1114
1115 return do_sys_open(AT_FDCWD, filename, flags, mode);
1116}
1117
1118SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1119 umode_t, mode)
1120{
1121 if (force_o_largefile())
1122 flags |= O_LARGEFILE;
1123
1124 return do_sys_open(dfd, filename, flags, mode);
1125}
1126
1127#ifdef CONFIG_COMPAT
1128/*
1129 * Exactly like sys_open(), except that it doesn't set the
1130 * O_LARGEFILE flag.
1131 */
1132COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1133{
1134 return do_sys_open(AT_FDCWD, filename, flags, mode);
1135}
1136
1137/*
1138 * Exactly like sys_openat(), except that it doesn't set the
1139 * O_LARGEFILE flag.
1140 */
1141COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1142{
1143 return do_sys_open(dfd, filename, flags, mode);
1144}
1145#endif
1146
1147#ifndef __alpha__
1148
1149/*
1150 * For backward compatibility? Maybe this should be moved
1151 * into arch/i386 instead?
1152 */
1153SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1154{
1155 return ksys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1156}
1157
1158#endif
1159
1160/*
1161 * "id" is the POSIX thread ID. We use the
1162 * files pointer for this..
1163 */
1164int filp_close(struct file *filp, fl_owner_t id)
1165{
1166 int retval = 0;
1167
1168 if (!file_count(filp)) {
1169 printk(KERN_ERR "VFS: Close: file count is 0\n");
1170 return 0;
1171 }
1172
1173 if (filp->f_op->flush)
1174 retval = filp->f_op->flush(filp, id);
1175
1176 if (likely(!(filp->f_mode & FMODE_PATH))) {
1177 dnotify_flush(filp, id);
1178 locks_remove_posix(filp, id);
1179 }
1180 fput(filp);
1181 return retval;
1182}
1183
1184EXPORT_SYMBOL(filp_close);
1185
1186/*
1187 * Careful here! We test whether the file pointer is NULL before
1188 * releasing the fd. This ensures that one clone task can't release
1189 * an fd while another clone is opening it.
1190 */
1191SYSCALL_DEFINE1(close, unsigned int, fd)
1192{
1193 int retval = __close_fd(current->files, fd);
1194
1195 /* can't restart close syscall because file table entry was cleared */
1196 if (unlikely(retval == -ERESTARTSYS ||
1197 retval == -ERESTARTNOINTR ||
1198 retval == -ERESTARTNOHAND ||
1199 retval == -ERESTART_RESTARTBLOCK))
1200 retval = -EINTR;
1201
1202 return retval;
1203}
1204
1205/*
1206 * This routine simulates a hangup on the tty, to arrange that users
1207 * are given clean terminals at login time.
1208 */
1209SYSCALL_DEFINE0(vhangup)
1210{
1211 if (capable(CAP_SYS_TTY_CONFIG)) {
1212 tty_vhangup_self();
1213 return 0;
1214 }
1215 return -EPERM;
1216}
1217
1218/*
1219 * Called when an inode is about to be open.
1220 * We use this to disallow opening large files on 32bit systems if
1221 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1222 * on this flag in sys_open.
1223 */
1224int generic_file_open(struct inode * inode, struct file * filp)
1225{
1226 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1227 return -EOVERFLOW;
1228 return 0;
1229}
1230
1231EXPORT_SYMBOL(generic_file_open);
1232
1233/*
1234 * This is used by subsystems that don't want seekable
1235 * file descriptors. The function is not supposed to ever fail, the only
1236 * reason it returns an 'int' and not 'void' is so that it can be plugged
1237 * directly into file_operations structure.
1238 */
1239int nonseekable_open(struct inode *inode, struct file *filp)
1240{
1241 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1242 return 0;
1243}
1244
1245EXPORT_SYMBOL(nonseekable_open);
1246
1247/*
1248 * stream_open is used by subsystems that want stream-like file descriptors.
1249 * Such file descriptors are not seekable and don't have notion of position
1250 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1251 * Contrary to file descriptors of other regular files, .read() and .write()
1252 * can run simultaneously.
1253 *
1254 * stream_open never fails and is marked to return int so that it could be
1255 * directly used as file_operations.open .
1256 */
1257int stream_open(struct inode *inode, struct file *filp)
1258{
1259 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1260 filp->f_mode |= FMODE_STREAM;
1261 return 0;
1262}
1263
1264EXPORT_SYMBOL(stream_open);