1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/fs/open.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8#include <linux/string.h>
9#include <linux/mm.h>
10#include <linux/file.h>
11#include <linux/fdtable.h>
12#include <linux/fsnotify.h>
13#include <linux/module.h>
14#include <linux/tty.h>
15#include <linux/namei.h>
16#include <linux/backing-dev.h>
17#include <linux/capability.h>
18#include <linux/securebits.h>
19#include <linux/security.h>
20#include <linux/mount.h>
21#include <linux/fcntl.h>
22#include <linux/slab.h>
23#include <linux/uaccess.h>
24#include <linux/fs.h>
25#include <linux/personality.h>
26#include <linux/pagemap.h>
27#include <linux/syscalls.h>
28#include <linux/rcupdate.h>
29#include <linux/audit.h>
30#include <linux/falloc.h>
31#include <linux/fs_struct.h>
32#include <linux/dnotify.h>
33#include <linux/compat.h>
34#include <linux/mnt_idmapping.h>
35#include <linux/filelock.h>
36
37#include "internal.h"
38
39int do_truncate(struct mnt_idmap *idmap, struct dentry *dentry,
40 loff_t length, unsigned int time_attrs, struct file *filp)
41{
42 int ret;
43 struct iattr newattrs;
44
45 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
46 if (length < 0)
47 return -EINVAL;
48
49 newattrs.ia_size = length;
50 newattrs.ia_valid = ATTR_SIZE | time_attrs;
51 if (filp) {
52 newattrs.ia_file = filp;
53 newattrs.ia_valid |= ATTR_FILE;
54 }
55
56 /* Remove suid, sgid, and file capabilities on truncate too */
57 ret = dentry_needs_remove_privs(idmap, dentry);
58 if (ret < 0)
59 return ret;
60 if (ret)
61 newattrs.ia_valid |= ret | ATTR_FORCE;
62
63 ret = inode_lock_killable(inode: dentry->d_inode);
64 if (ret)
65 return ret;
66
67 /* Note any delegations or leases have already been broken: */
68 ret = notify_change(idmap, dentry, &newattrs, NULL);
69 inode_unlock(inode: dentry->d_inode);
70 return ret;
71}
72
73int vfs_truncate(const struct path *path, loff_t length)
74{
75 struct mnt_idmap *idmap;
76 struct inode *inode;
77 int error;
78
79 inode = path->dentry->d_inode;
80
81 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
82 if (S_ISDIR(inode->i_mode))
83 return -EISDIR;
84 if (!S_ISREG(inode->i_mode))
85 return -EINVAL;
86
87 idmap = mnt_idmap(mnt: path->mnt);
88 error = inode_permission(idmap, inode, MAY_WRITE);
89 if (error)
90 return error;
91
92 error = fsnotify_truncate_perm(path, length);
93 if (error)
94 return error;
95
96 error = mnt_want_write(mnt: path->mnt);
97 if (error)
98 return error;
99
100 error = -EPERM;
101 if (IS_APPEND(inode))
102 goto mnt_drop_write_and_out;
103
104 error = get_write_access(inode);
105 if (error)
106 goto mnt_drop_write_and_out;
107
108 /*
109 * Make sure that there are no leases. get_write_access() protects
110 * against the truncate racing with a lease-granting setlease().
111 */
112 error = break_lease(inode, O_WRONLY);
113 if (error)
114 goto put_write_and_out;
115
116 error = security_path_truncate(path);
117 if (!error)
118 error = do_truncate(idmap, dentry: path->dentry, length, time_attrs: 0, NULL);
119
120put_write_and_out:
121 put_write_access(inode);
122mnt_drop_write_and_out:
123 mnt_drop_write(mnt: path->mnt);
124
125 return error;
126}
127EXPORT_SYMBOL_GPL(vfs_truncate);
128
129int do_sys_truncate(const char __user *pathname, loff_t length)
130{
131 unsigned int lookup_flags = LOOKUP_FOLLOW;
132 struct path path;
133 int error;
134
135 if (length < 0) /* sorry, but loff_t says... */
136 return -EINVAL;
137
138retry:
139 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
140 if (!error) {
141 error = vfs_truncate(&path, length);
142 path_put(&path);
143 }
144 if (retry_estale(error, flags: lookup_flags)) {
145 lookup_flags |= LOOKUP_REVAL;
146 goto retry;
147 }
148 return error;
149}
150
151SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
152{
153 return do_sys_truncate(pathname: path, length);
154}
155
156#ifdef CONFIG_COMPAT
157COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
158{
159 return do_sys_truncate(pathname: path, length);
160}
161#endif
162
163int do_ftruncate(struct file *file, loff_t length, int small)
164{
165 struct inode *inode;
166 struct dentry *dentry;
167 int error;
168
169 /* explicitly opened as large or we are on 64-bit box */
170 if (file->f_flags & O_LARGEFILE)
171 small = 0;
172
173 dentry = file->f_path.dentry;
174 inode = dentry->d_inode;
175 if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
176 return -EINVAL;
177
178 /* Cannot ftruncate over 2^31 bytes without large file support */
179 if (small && length > MAX_NON_LFS)
180 return -EINVAL;
181
182 /* Check IS_APPEND on real upper inode */
183 if (IS_APPEND(file_inode(file)))
184 return -EPERM;
185
186 error = security_file_truncate(file);
187 if (error)
188 return error;
189
190 error = fsnotify_truncate_perm(path: &file->f_path, length);
191 if (error)
192 return error;
193
194 sb_start_write(sb: inode->i_sb);
195 error = do_truncate(idmap: file_mnt_idmap(file), dentry, length,
196 ATTR_MTIME | ATTR_CTIME, filp: file);
197 sb_end_write(sb: inode->i_sb);
198
199 return error;
200}
201
202int do_sys_ftruncate(unsigned int fd, loff_t length, int small)
203{
204 if (length < 0)
205 return -EINVAL;
206 CLASS(fd, f)(fd);
207 if (fd_empty(f))
208 return -EBADF;
209
210 return do_ftruncate(fd_file(f), length, small);
211}
212
213SYSCALL_DEFINE2(ftruncate, unsigned int, fd, off_t, length)
214{
215 return do_sys_ftruncate(fd, length, small: 1);
216}
217
218#ifdef CONFIG_COMPAT
219COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_off_t, length)
220{
221 return do_sys_ftruncate(fd, length, small: 1);
222}
223#endif
224
225/* LFS versions of truncate are only needed on 32 bit machines */
226#if BITS_PER_LONG == 32
227SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
228{
229 return do_sys_truncate(path, length);
230}
231
232SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
233{
234 return do_sys_ftruncate(fd, length, 0);
235}
236#endif /* BITS_PER_LONG == 32 */
237
238#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64)
239COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname,
240 compat_arg_u64_dual(length))
241{
242 return ksys_truncate(pathname, compat_arg_u64_glue(length));
243}
244#endif
245
246#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64)
247COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd,
248 compat_arg_u64_dual(length))
249{
250 return ksys_ftruncate(fd, compat_arg_u64_glue(length));
251}
252#endif
253
254int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
255{
256 struct inode *inode = file_inode(f: file);
257 int ret;
258 loff_t sum;
259
260 if (offset < 0 || len <= 0)
261 return -EINVAL;
262
263 if (mode & ~(FALLOC_FL_MODE_MASK | FALLOC_FL_KEEP_SIZE))
264 return -EOPNOTSUPP;
265
266 /*
267 * Modes are exclusive, even if that is not obvious from the encoding
268 * as bit masks and the mix with the flag in the same namespace.
269 *
270 * To make things even more complicated, FALLOC_FL_ALLOCATE_RANGE is
271 * encoded as no bit set.
272 */
273 switch (mode & FALLOC_FL_MODE_MASK) {
274 case FALLOC_FL_ALLOCATE_RANGE:
275 case FALLOC_FL_UNSHARE_RANGE:
276 case FALLOC_FL_ZERO_RANGE:
277 break;
278 case FALLOC_FL_PUNCH_HOLE:
279 if (!(mode & FALLOC_FL_KEEP_SIZE))
280 return -EOPNOTSUPP;
281 break;
282 case FALLOC_FL_COLLAPSE_RANGE:
283 case FALLOC_FL_INSERT_RANGE:
284 if (mode & FALLOC_FL_KEEP_SIZE)
285 return -EOPNOTSUPP;
286 break;
287 default:
288 return -EOPNOTSUPP;
289 }
290
291 if (!(file->f_mode & FMODE_WRITE))
292 return -EBADF;
293
294 /*
295 * On append-only files only space preallocation is supported.
296 */
297 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
298 return -EPERM;
299
300 if (IS_IMMUTABLE(inode))
301 return -EPERM;
302
303 /*
304 * We cannot allow any fallocate operation on an active swapfile
305 */
306 if (IS_SWAPFILE(inode))
307 return -ETXTBSY;
308
309 /*
310 * Revalidate the write permissions, in case security policy has
311 * changed since the files were opened.
312 */
313 ret = security_file_permission(file, MAY_WRITE);
314 if (ret)
315 return ret;
316
317 ret = fsnotify_file_area_perm(file, MAY_WRITE, ppos: &offset, count: len);
318 if (ret)
319 return ret;
320
321 if (S_ISFIFO(inode->i_mode))
322 return -ESPIPE;
323
324 if (S_ISDIR(inode->i_mode))
325 return -EISDIR;
326
327 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
328 return -ENODEV;
329
330 /* Check for wraparound */
331 if (check_add_overflow(offset, len, &sum))
332 return -EFBIG;
333
334 if (sum > inode->i_sb->s_maxbytes)
335 return -EFBIG;
336
337 if (!file->f_op->fallocate)
338 return -EOPNOTSUPP;
339
340 file_start_write(file);
341 ret = file->f_op->fallocate(file, mode, offset, len);
342
343 /*
344 * Create inotify and fanotify events.
345 *
346 * To keep the logic simple always create events if fallocate succeeds.
347 * This implies that events are even created if the file size remains
348 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
349 */
350 if (ret == 0)
351 fsnotify_modify(file);
352
353 file_end_write(file);
354 return ret;
355}
356EXPORT_SYMBOL_GPL(vfs_fallocate);
357
358int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
359{
360 CLASS(fd, f)(fd);
361
362 if (fd_empty(f))
363 return -EBADF;
364
365 return vfs_fallocate(fd_file(f), mode, offset, len);
366}
367
368SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
369{
370 return ksys_fallocate(fd, mode, offset, len);
371}
372
373#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE)
374COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset),
375 compat_arg_u64_dual(len))
376{
377 return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset),
378 compat_arg_u64_glue(len));
379}
380#endif
381
382/*
383 * access() needs to use the real uid/gid, not the effective uid/gid.
384 * We do this by temporarily clearing all FS-related capabilities and
385 * switching the fsuid/fsgid around to the real ones.
386 *
387 * Creating new credentials is expensive, so we try to skip doing it,
388 * which we can if the result would match what we already got.
389 */
390static bool access_need_override_creds(int flags)
391{
392 const struct cred *cred;
393
394 if (flags & AT_EACCESS)
395 return false;
396
397 cred = current_cred();
398 if (!uid_eq(left: cred->fsuid, right: cred->uid) ||
399 !gid_eq(left: cred->fsgid, right: cred->gid))
400 return true;
401
402 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
403 kuid_t root_uid = make_kuid(from: cred->user_ns, uid: 0);
404 if (!uid_eq(left: cred->uid, right: root_uid)) {
405 if (!cap_isclear(a: cred->cap_effective))
406 return true;
407 } else {
408 if (!cap_isidentical(a: cred->cap_effective,
409 b: cred->cap_permitted))
410 return true;
411 }
412 }
413
414 return false;
415}
416
417static const struct cred *access_override_creds(void)
418{
419 struct cred *override_cred;
420
421 override_cred = prepare_creds();
422 if (!override_cred)
423 return NULL;
424
425 /*
426 * XXX access_need_override_creds performs checks in hopes of skipping
427 * this work. Make sure it stays in sync if making any changes in this
428 * routine.
429 */
430
431 override_cred->fsuid = override_cred->uid;
432 override_cred->fsgid = override_cred->gid;
433
434 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
435 /* Clear the capabilities if we switch to a non-root user */
436 kuid_t root_uid = make_kuid(from: override_cred->user_ns, uid: 0);
437 if (!uid_eq(left: override_cred->uid, right: root_uid))
438 cap_clear(override_cred->cap_effective);
439 else
440 override_cred->cap_effective =
441 override_cred->cap_permitted;
442 }
443
444 /*
445 * The new set of credentials can *only* be used in
446 * task-synchronous circumstances, and does not need
447 * RCU freeing, unless somebody then takes a separate
448 * reference to it.
449 *
450 * NOTE! This is _only_ true because this credential
451 * is used purely for override_creds() that installs
452 * it as the subjective cred. Other threads will be
453 * accessing ->real_cred, not the subjective cred.
454 *
455 * If somebody _does_ make a copy of this (using the
456 * 'get_current_cred()' function), that will clear the
457 * non_rcu field, because now that other user may be
458 * expecting RCU freeing. But normal thread-synchronous
459 * cred accesses will keep things non-racy to avoid RCU
460 * freeing.
461 */
462 override_cred->non_rcu = 1;
463 return override_creds(override_cred);
464}
465
466static int do_faccessat(int dfd, const char __user *filename, int mode, int flags)
467{
468 struct path path;
469 struct inode *inode;
470 int res;
471 unsigned int lookup_flags = LOOKUP_FOLLOW;
472 const struct cred *old_cred = NULL;
473
474 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
475 return -EINVAL;
476
477 if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
478 return -EINVAL;
479
480 if (flags & AT_SYMLINK_NOFOLLOW)
481 lookup_flags &= ~LOOKUP_FOLLOW;
482 if (flags & AT_EMPTY_PATH)
483 lookup_flags |= LOOKUP_EMPTY;
484
485 if (access_need_override_creds(flags)) {
486 old_cred = access_override_creds();
487 if (!old_cred)
488 return -ENOMEM;
489 }
490
491retry:
492 res = user_path_at(dfd, filename, lookup_flags, &path);
493 if (res)
494 goto out;
495
496 inode = d_backing_inode(upper: path.dentry);
497
498 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
499 /*
500 * MAY_EXEC on regular files is denied if the fs is mounted
501 * with the "noexec" flag.
502 */
503 res = -EACCES;
504 if (path_noexec(path: &path))
505 goto out_path_release;
506 }
507
508 res = inode_permission(mnt_idmap(mnt: path.mnt), inode, mode | MAY_ACCESS);
509 /* SuS v2 requires we report a read only fs too */
510 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
511 goto out_path_release;
512 /*
513 * This is a rare case where using __mnt_is_readonly()
514 * is OK without a mnt_want/drop_write() pair. Since
515 * no actual write to the fs is performed here, we do
516 * not need to telegraph to that to anyone.
517 *
518 * By doing this, we accept that this access is
519 * inherently racy and know that the fs may change
520 * state before we even see this result.
521 */
522 if (__mnt_is_readonly(mnt: path.mnt))
523 res = -EROFS;
524
525out_path_release:
526 path_put(&path);
527 if (retry_estale(error: res, flags: lookup_flags)) {
528 lookup_flags |= LOOKUP_REVAL;
529 goto retry;
530 }
531out:
532 if (old_cred)
533 put_cred(cred: revert_creds(revert_cred: old_cred));
534
535 return res;
536}
537
538SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
539{
540 return do_faccessat(dfd, filename, mode, flags: 0);
541}
542
543SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
544 int, flags)
545{
546 return do_faccessat(dfd, filename, mode, flags);
547}
548
549SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
550{
551 return do_faccessat(AT_FDCWD, filename, mode, flags: 0);
552}
553
554SYSCALL_DEFINE1(chdir, const char __user *, filename)
555{
556 struct path path;
557 int error;
558 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
559retry:
560 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
561 if (error)
562 goto out;
563
564 error = path_permission(path: &path, MAY_EXEC | MAY_CHDIR);
565 if (error)
566 goto dput_and_out;
567
568 set_fs_pwd(current->fs, &path);
569
570dput_and_out:
571 path_put(&path);
572 if (retry_estale(error, flags: lookup_flags)) {
573 lookup_flags |= LOOKUP_REVAL;
574 goto retry;
575 }
576out:
577 return error;
578}
579
580SYSCALL_DEFINE1(fchdir, unsigned int, fd)
581{
582 CLASS(fd_raw, f)(fd);
583 int error;
584
585 if (fd_empty(f))
586 return -EBADF;
587
588 if (!d_can_lookup(fd_file(f)->f_path.dentry))
589 return -ENOTDIR;
590
591 error = file_permission(fd_file(f), MAY_EXEC | MAY_CHDIR);
592 if (!error)
593 set_fs_pwd(current->fs, &fd_file(f)->f_path);
594 return error;
595}
596
597SYSCALL_DEFINE1(chroot, const char __user *, filename)
598{
599 struct path path;
600 int error;
601 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
602retry:
603 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
604 if (error)
605 goto out;
606
607 error = path_permission(path: &path, MAY_EXEC | MAY_CHDIR);
608 if (error)
609 goto dput_and_out;
610
611 error = -EPERM;
612 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
613 goto dput_and_out;
614 error = security_path_chroot(path: &path);
615 if (error)
616 goto dput_and_out;
617
618 set_fs_root(current->fs, &path);
619 error = 0;
620dput_and_out:
621 path_put(&path);
622 if (retry_estale(error, flags: lookup_flags)) {
623 lookup_flags |= LOOKUP_REVAL;
624 goto retry;
625 }
626out:
627 return error;
628}
629
630int chmod_common(const struct path *path, umode_t mode)
631{
632 struct inode *inode = path->dentry->d_inode;
633 struct inode *delegated_inode = NULL;
634 struct iattr newattrs;
635 int error;
636
637 error = mnt_want_write(mnt: path->mnt);
638 if (error)
639 return error;
640retry_deleg:
641 error = inode_lock_killable(inode);
642 if (error)
643 goto out_mnt_unlock;
644 error = security_path_chmod(path, mode);
645 if (error)
646 goto out_unlock;
647 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
648 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
649 error = notify_change(mnt_idmap(mnt: path->mnt), path->dentry,
650 &newattrs, &delegated_inode);
651out_unlock:
652 inode_unlock(inode);
653 if (delegated_inode) {
654 error = break_deleg_wait(delegated_inode: &delegated_inode);
655 if (!error)
656 goto retry_deleg;
657 }
658out_mnt_unlock:
659 mnt_drop_write(mnt: path->mnt);
660 return error;
661}
662
663int vfs_fchmod(struct file *file, umode_t mode)
664{
665 audit_file(file);
666 return chmod_common(path: &file->f_path, mode);
667}
668
669SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
670{
671 CLASS(fd, f)(fd);
672
673 if (fd_empty(f))
674 return -EBADF;
675
676 return vfs_fchmod(fd_file(f), mode);
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: &path, mode);
697 path_put(&path);
698 if (retry_estale(error, flags: 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, flags: 0);
716}
717
718SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
719{
720 return do_fchmodat(AT_FDCWD, filename, mode, flags: 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(uid: 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(gid: 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(), uid: user);
765 gid = make_kgid(current_user_ns(), gid: group);
766
767 idmap = mnt_idmap(mnt: 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(attr: &newattrs, kuid: uid))
775 return -EINVAL;
776 if ((group != (gid_t)-1) && !setattr_vfsgid(attr: &newattrs, kgid: gid))
777 return -EINVAL;
778 error = inode_lock_killable(inode);
779 if (error)
780 return error;
781 if (!S_ISDIR(inode->i_mode))
782 newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV |
783 setattr_should_drop_sgid(idmap, inode);
784 /* Continue to send actual fs values, not the mount values. */
785 error = security_path_chown(
786 path,
787 uid: from_vfsuid(idmap, fs_userns, vfsuid: newattrs.ia_vfsuid),
788 gid: from_vfsgid(idmap, fs_userns, vfsgid: newattrs.ia_vfsgid));
789 if (!error)
790 error = notify_change(idmap, path->dentry, &newattrs,
791 &delegated_inode);
792 inode_unlock(inode);
793 if (delegated_inode) {
794 error = break_deleg_wait(delegated_inode: &delegated_inode);
795 if (!error)
796 goto retry_deleg;
797 }
798 return error;
799}
800
801int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
802 int flag)
803{
804 struct path path;
805 int error = -EINVAL;
806 int lookup_flags;
807
808 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
809 goto out;
810
811 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
812 if (flag & AT_EMPTY_PATH)
813 lookup_flags |= LOOKUP_EMPTY;
814retry:
815 error = user_path_at(dfd, filename, lookup_flags, &path);
816 if (error)
817 goto out;
818 error = mnt_want_write(mnt: path.mnt);
819 if (error)
820 goto out_release;
821 error = chown_common(path: &path, user, group);
822 mnt_drop_write(mnt: path.mnt);
823out_release:
824 path_put(&path);
825 if (retry_estale(error, flags: lookup_flags)) {
826 lookup_flags |= LOOKUP_REVAL;
827 goto retry;
828 }
829out:
830 return error;
831}
832
833SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
834 gid_t, group, int, flag)
835{
836 return do_fchownat(dfd, filename, user, group, flag);
837}
838
839SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
840{
841 return do_fchownat(AT_FDCWD, filename, user, group, flag: 0);
842}
843
844SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
845{
846 return do_fchownat(AT_FDCWD, filename, user, group,
847 AT_SYMLINK_NOFOLLOW);
848}
849
850int vfs_fchown(struct file *file, uid_t user, gid_t group)
851{
852 int error;
853
854 error = mnt_want_write_file(file);
855 if (error)
856 return error;
857 audit_file(file);
858 error = chown_common(path: &file->f_path, user, group);
859 mnt_drop_write_file(file);
860 return error;
861}
862
863int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
864{
865 CLASS(fd, f)(fd);
866
867 if (fd_empty(f))
868 return -EBADF;
869
870 return vfs_fchown(fd_file(f), user, group);
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(inode: f->f_inode);
883 if (unlikely(error))
884 return error;
885 error = mnt_get_write_access(mnt: 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(mnt: 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(mnt: f->f_path.mnt);
897cleanup_inode:
898 put_write_access(inode: f->f_inode);
899 return error;
900}
901
902static int do_dentry_open(struct file *f,
903 int (*open)(struct inode *, struct file *))
904{
905 static const struct file_operations empty_fops = {};
906 struct inode *inode = f->f_path.dentry->d_inode;
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(mapping: f->f_mapping);
913 f->f_sb_err = file_sample_sb_err(file: f);
914
915 if (unlikely(f->f_flags & O_PATH)) {
916 f->f_mode = FMODE_PATH | FMODE_OPENED;
917 file_set_fsnotify_mode(file: f, FMODE_NONOTIFY);
918 f->f_op = &empty_fops;
919 return 0;
920 }
921
922 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
923 i_readcount_inc(inode);
924 } else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
925 error = file_get_write_access(f);
926 if (unlikely(error))
927 goto cleanup_file;
928 f->f_mode |= FMODE_WRITER;
929 }
930
931 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
932 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
933 f->f_mode |= FMODE_ATOMIC_POS;
934
935 f->f_op = fops_get(inode->i_fop);
936 if (WARN_ON(!f->f_op)) {
937 error = -ENODEV;
938 goto cleanup_all;
939 }
940
941 error = security_file_open(file: f);
942 if (error)
943 goto cleanup_all;
944
945 /*
946 * Set FMODE_NONOTIFY_* bits according to existing permission watches.
947 * If FMODE_NONOTIFY mode was already set for an fanotify fd or for a
948 * pseudo file, this call will not change the mode.
949 */
950 file_set_fsnotify_mode_from_watchers(file: f);
951 error = fsnotify_open_perm(file: f);
952 if (error)
953 goto cleanup_all;
954
955 error = break_lease(inode: file_inode(f), mode: f->f_flags);
956 if (error)
957 goto cleanup_all;
958
959 /* normally all 3 are set; ->open() can clear them if needed */
960 f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
961 if (!open)
962 open = f->f_op->open;
963 if (open) {
964 error = open(inode, f);
965 if (error)
966 goto cleanup_all;
967 }
968 f->f_mode |= FMODE_OPENED;
969 if ((f->f_mode & FMODE_READ) &&
970 likely(f->f_op->read || f->f_op->read_iter))
971 f->f_mode |= FMODE_CAN_READ;
972 if ((f->f_mode & FMODE_WRITE) &&
973 likely(f->f_op->write || f->f_op->write_iter))
974 f->f_mode |= FMODE_CAN_WRITE;
975 if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek)
976 f->f_mode &= ~FMODE_LSEEK;
977 if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO)
978 f->f_mode |= FMODE_CAN_ODIRECT;
979
980 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
981 f->f_iocb_flags = iocb_flags(file: f);
982
983 file_ra_state_init(ra: &f->f_ra, mapping: f->f_mapping->host->i_mapping);
984
985 if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT))
986 return -EINVAL;
987
988 /*
989 * XXX: Huge page cache doesn't support writing yet. Drop all page
990 * cache for this file before processing writes.
991 */
992 if (f->f_mode & FMODE_WRITE) {
993 /*
994 * Depends on full fence from get_write_access() to synchronize
995 * against collapse_file() regarding i_writecount and nr_thps
996 * updates. Ensures subsequent insertion of THPs into the page
997 * cache will fail.
998 */
999 if (filemap_nr_thps(mapping: inode->i_mapping)) {
1000 struct address_space *mapping = inode->i_mapping;
1001
1002 filemap_invalidate_lock(mapping: inode->i_mapping);
1003 /*
1004 * unmap_mapping_range just need to be called once
1005 * here, because the private pages is not need to be
1006 * unmapped mapping (e.g. data segment of dynamic
1007 * shared libraries here).
1008 */
1009 unmap_mapping_range(mapping, holebegin: 0, holelen: 0, even_cows: 0);
1010 truncate_inode_pages(mapping, 0);
1011 filemap_invalidate_unlock(mapping: inode->i_mapping);
1012 }
1013 }
1014
1015 return 0;
1016
1017cleanup_all:
1018 if (WARN_ON_ONCE(error > 0))
1019 error = -EINVAL;
1020 fops_put(f->f_op);
1021 put_file_access(file: f);
1022cleanup_file:
1023 path_put(&f->f_path);
1024 f->f_path.mnt = NULL;
1025 f->f_path.dentry = NULL;
1026 f->f_inode = NULL;
1027 return error;
1028}
1029
1030/**
1031 * finish_open - finish opening a file
1032 * @file: file pointer
1033 * @dentry: pointer to dentry
1034 * @open: open callback
1035 *
1036 * This can be used to finish opening a file passed to i_op->atomic_open().
1037 *
1038 * If the open callback is set to NULL, then the standard f_op->open()
1039 * filesystem callback is substituted.
1040 *
1041 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
1042 * the return value of d_splice_alias(), then the caller needs to perform dput()
1043 * on it after finish_open().
1044 *
1045 * Returns zero on success or -errno if the open failed.
1046 */
1047int finish_open(struct file *file, struct dentry *dentry,
1048 int (*open)(struct inode *, struct file *))
1049{
1050 BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
1051
1052 file->f_path.dentry = dentry;
1053 return do_dentry_open(f: file, open);
1054}
1055EXPORT_SYMBOL(finish_open);
1056
1057/**
1058 * finish_no_open - finish ->atomic_open() without opening the file
1059 *
1060 * @file: file pointer
1061 * @dentry: dentry or NULL (as returned from ->lookup())
1062 *
1063 * This can be used to set the result of a successful lookup in ->atomic_open().
1064 *
1065 * NB: unlike finish_open() this function does consume the dentry reference and
1066 * the caller need not dput() it.
1067 *
1068 * Returns "0" which must be the return value of ->atomic_open() after having
1069 * called this function.
1070 */
1071int finish_no_open(struct file *file, struct dentry *dentry)
1072{
1073 file->f_path.dentry = dentry;
1074 return 0;
1075}
1076EXPORT_SYMBOL(finish_no_open);
1077
1078char *file_path(struct file *filp, char *buf, int buflen)
1079{
1080 return d_path(&filp->f_path, buf, buflen);
1081}
1082EXPORT_SYMBOL(file_path);
1083
1084/**
1085 * vfs_open - open the file at the given path
1086 * @path: path to open
1087 * @file: newly allocated file with f_flag initialized
1088 */
1089int vfs_open(const struct path *path, struct file *file)
1090{
1091 int ret;
1092
1093 file->f_path = *path;
1094 ret = do_dentry_open(f: file, NULL);
1095 if (!ret) {
1096 /*
1097 * Once we return a file with FMODE_OPENED, __fput() will call
1098 * fsnotify_close(), so we need fsnotify_open() here for
1099 * symmetry.
1100 */
1101 fsnotify_open(file);
1102 }
1103 return ret;
1104}
1105
1106struct file *dentry_open(const struct path *path, int flags,
1107 const struct cred *cred)
1108{
1109 int error;
1110 struct file *f;
1111
1112 /* We must always pass in a valid mount pointer. */
1113 BUG_ON(!path->mnt);
1114
1115 f = alloc_empty_file(flags, cred);
1116 if (!IS_ERR(ptr: f)) {
1117 error = vfs_open(path, file: f);
1118 if (error) {
1119 fput(f);
1120 f = ERR_PTR(error);
1121 }
1122 }
1123 return f;
1124}
1125EXPORT_SYMBOL(dentry_open);
1126
1127struct file *dentry_open_nonotify(const struct path *path, int flags,
1128 const struct cred *cred)
1129{
1130 struct file *f = alloc_empty_file(flags, cred);
1131 if (!IS_ERR(ptr: f)) {
1132 int error;
1133
1134 file_set_fsnotify_mode(file: f, FMODE_NONOTIFY);
1135 error = vfs_open(path, file: f);
1136 if (error) {
1137 fput(f);
1138 f = ERR_PTR(error);
1139 }
1140 }
1141 return f;
1142}
1143
1144/**
1145 * dentry_create - Create and open a file
1146 * @path: path to create
1147 * @flags: O_ flags
1148 * @mode: mode bits for new file
1149 * @cred: credentials to use
1150 *
1151 * Caller must hold the parent directory's lock, and have prepared
1152 * a negative dentry, placed in @path->dentry, for the new file.
1153 *
1154 * Caller sets @path->mnt to the vfsmount of the filesystem where
1155 * the new file is to be created. The parent directory and the
1156 * negative dentry must reside on the same filesystem instance.
1157 *
1158 * On success, returns a "struct file *". Otherwise a ERR_PTR
1159 * is returned.
1160 */
1161struct file *dentry_create(const struct path *path, int flags, umode_t mode,
1162 const struct cred *cred)
1163{
1164 struct file *f;
1165 int error;
1166
1167 f = alloc_empty_file(flags, cred);
1168 if (IS_ERR(ptr: f))
1169 return f;
1170
1171 error = vfs_create(mnt_idmap(mnt: path->mnt),
1172 d_inode(dentry: path->dentry->d_parent),
1173 path->dentry, mode, true);
1174 if (!error)
1175 error = vfs_open(path, file: f);
1176
1177 if (unlikely(error)) {
1178 fput(f);
1179 return ERR_PTR(error);
1180 }
1181 return f;
1182}
1183EXPORT_SYMBOL(dentry_create);
1184
1185/**
1186 * kernel_file_open - open a file for kernel internal use
1187 * @path: path of the file to open
1188 * @flags: open flags
1189 * @cred: credentials for open
1190 *
1191 * Open a file for use by in-kernel consumers. The file is not accounted
1192 * against nr_files and must not be installed into the file descriptor
1193 * table.
1194 *
1195 * Return: Opened file on success, an error pointer on failure.
1196 */
1197struct file *kernel_file_open(const struct path *path, int flags,
1198 const struct cred *cred)
1199{
1200 struct file *f;
1201 int error;
1202
1203 f = alloc_empty_file_noaccount(flags, cred);
1204 if (IS_ERR(ptr: f))
1205 return f;
1206
1207 f->f_path = *path;
1208 error = do_dentry_open(f, NULL);
1209 if (error) {
1210 fput(f);
1211 return ERR_PTR(error);
1212 }
1213
1214 fsnotify_open(file: f);
1215 return f;
1216}
1217EXPORT_SYMBOL_GPL(kernel_file_open);
1218
1219#define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE))
1220#define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
1221
1222inline struct open_how build_open_how(int flags, umode_t mode)
1223{
1224 struct open_how how = {
1225 .flags = flags & VALID_OPEN_FLAGS,
1226 .mode = mode & S_IALLUGO,
1227 };
1228
1229 /* O_PATH beats everything else. */
1230 if (how.flags & O_PATH)
1231 how.flags &= O_PATH_FLAGS;
1232 /* Modes should only be set for create-like flags. */
1233 if (!WILL_CREATE(how.flags))
1234 how.mode = 0;
1235 return how;
1236}
1237
1238inline int build_open_flags(const struct open_how *how, struct open_flags *op)
1239{
1240 u64 flags = how->flags;
1241 u64 strip = O_CLOEXEC;
1242 int lookup_flags = 0;
1243 int acc_mode = ACC_MODE(flags);
1244
1245 BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
1246 "struct open_flags doesn't yet handle flags > 32 bits");
1247
1248 /*
1249 * Strip flags that aren't relevant in determining struct open_flags.
1250 */
1251 flags &= ~strip;
1252
1253 /*
1254 * Older syscalls implicitly clear all of the invalid flags or argument
1255 * values before calling build_open_flags(), but openat2(2) checks all
1256 * of its arguments.
1257 */
1258 if (flags & ~VALID_OPEN_FLAGS)
1259 return -EINVAL;
1260 if (how->resolve & ~VALID_RESOLVE_FLAGS)
1261 return -EINVAL;
1262
1263 /* Scoping flags are mutually exclusive. */
1264 if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
1265 return -EINVAL;
1266
1267 /* Deal with the mode. */
1268 if (WILL_CREATE(flags)) {
1269 if (how->mode & ~S_IALLUGO)
1270 return -EINVAL;
1271 op->mode = how->mode | S_IFREG;
1272 } else {
1273 if (how->mode != 0)
1274 return -EINVAL;
1275 op->mode = 0;
1276 }
1277
1278 /*
1279 * Block bugs where O_DIRECTORY | O_CREAT created regular files.
1280 * Note, that blocking O_DIRECTORY | O_CREAT here also protects
1281 * O_TMPFILE below which requires O_DIRECTORY being raised.
1282 */
1283 if ((flags & (O_DIRECTORY | O_CREAT)) == (O_DIRECTORY | O_CREAT))
1284 return -EINVAL;
1285
1286 /* Now handle the creative implementation of O_TMPFILE. */
1287 if (flags & __O_TMPFILE) {
1288 /*
1289 * In order to ensure programs get explicit errors when trying
1290 * to use O_TMPFILE on old kernels we enforce that O_DIRECTORY
1291 * is raised alongside __O_TMPFILE.
1292 */
1293 if (!(flags & O_DIRECTORY))
1294 return -EINVAL;
1295 if (!(acc_mode & MAY_WRITE))
1296 return -EINVAL;
1297 }
1298 if (flags & O_PATH) {
1299 /* O_PATH only permits certain other flags to be set. */
1300 if (flags & ~O_PATH_FLAGS)
1301 return -EINVAL;
1302 acc_mode = 0;
1303 }
1304
1305 /*
1306 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1307 * check for O_DSYNC if the need any syncing at all we enforce it's
1308 * always set instead of having to deal with possibly weird behaviour
1309 * for malicious applications setting only __O_SYNC.
1310 */
1311 if (flags & __O_SYNC)
1312 flags |= O_DSYNC;
1313
1314 op->open_flag = flags;
1315
1316 /* O_TRUNC implies we need access checks for write permissions */
1317 if (flags & O_TRUNC)
1318 acc_mode |= MAY_WRITE;
1319
1320 /* Allow the LSM permission hook to distinguish append
1321 access from general write access. */
1322 if (flags & O_APPEND)
1323 acc_mode |= MAY_APPEND;
1324
1325 op->acc_mode = acc_mode;
1326
1327 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1328
1329 if (flags & O_CREAT) {
1330 op->intent |= LOOKUP_CREATE;
1331 if (flags & O_EXCL) {
1332 op->intent |= LOOKUP_EXCL;
1333 flags |= O_NOFOLLOW;
1334 }
1335 }
1336
1337 if (flags & O_DIRECTORY)
1338 lookup_flags |= LOOKUP_DIRECTORY;
1339 if (!(flags & O_NOFOLLOW))
1340 lookup_flags |= LOOKUP_FOLLOW;
1341
1342 if (how->resolve & RESOLVE_NO_XDEV)
1343 lookup_flags |= LOOKUP_NO_XDEV;
1344 if (how->resolve & RESOLVE_NO_MAGICLINKS)
1345 lookup_flags |= LOOKUP_NO_MAGICLINKS;
1346 if (how->resolve & RESOLVE_NO_SYMLINKS)
1347 lookup_flags |= LOOKUP_NO_SYMLINKS;
1348 if (how->resolve & RESOLVE_BENEATH)
1349 lookup_flags |= LOOKUP_BENEATH;
1350 if (how->resolve & RESOLVE_IN_ROOT)
1351 lookup_flags |= LOOKUP_IN_ROOT;
1352 if (how->resolve & RESOLVE_CACHED) {
1353 /* Don't bother even trying for create/truncate/tmpfile open */
1354 if (flags & (O_TRUNC | O_CREAT | __O_TMPFILE))
1355 return -EAGAIN;
1356 lookup_flags |= LOOKUP_CACHED;
1357 }
1358
1359 op->lookup_flags = lookup_flags;
1360 return 0;
1361}
1362
1363/**
1364 * file_open_name - open file and return file pointer
1365 *
1366 * @name: struct filename containing path to open
1367 * @flags: open flags as per the open(2) second argument
1368 * @mode: mode for the new file if O_CREAT is set, else ignored
1369 *
1370 * This is the helper to open a file from kernelspace if you really
1371 * have to. But in generally you should not do this, so please move
1372 * along, nothing to see here..
1373 */
1374struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1375{
1376 struct open_flags op;
1377 struct open_how how = build_open_how(flags, mode);
1378 int err = build_open_flags(how: &how, op: &op);
1379 if (err)
1380 return ERR_PTR(error: err);
1381 return do_filp_open(AT_FDCWD, pathname: name, op: &op);
1382}
1383
1384/**
1385 * filp_open - open file and return file pointer
1386 *
1387 * @filename: path to open
1388 * @flags: open flags as per the open(2) second argument
1389 * @mode: mode for the new file if O_CREAT is set, else ignored
1390 *
1391 * This is the helper to open a file from kernelspace if you really
1392 * have to. But in generally you should not do this, so please move
1393 * along, nothing to see here..
1394 */
1395struct file *filp_open(const char *filename, int flags, umode_t mode)
1396{
1397 struct filename *name = getname_kernel(filename);
1398 struct file *file = ERR_CAST(ptr: name);
1399
1400 if (!IS_ERR(ptr: name)) {
1401 file = file_open_name(name, flags, mode);
1402 putname(name);
1403 }
1404 return file;
1405}
1406EXPORT_SYMBOL(filp_open);
1407
1408struct file *file_open_root(const struct path *root,
1409 const char *filename, int flags, umode_t mode)
1410{
1411 struct open_flags op;
1412 struct open_how how = build_open_how(flags, mode);
1413 int err = build_open_flags(how: &how, op: &op);
1414 if (err)
1415 return ERR_PTR(error: err);
1416 return do_file_open_root(root, filename, &op);
1417}
1418EXPORT_SYMBOL(file_open_root);
1419
1420static int do_sys_openat2(int dfd, const char __user *filename,
1421 struct open_how *how)
1422{
1423 struct open_flags op;
1424 struct filename *tmp;
1425 int err, fd;
1426
1427 err = build_open_flags(how, op: &op);
1428 if (unlikely(err))
1429 return err;
1430
1431 tmp = getname(name: filename);
1432 if (IS_ERR(ptr: tmp))
1433 return PTR_ERR(ptr: tmp);
1434
1435 fd = get_unused_fd_flags(flags: how->flags);
1436 if (likely(fd >= 0)) {
1437 struct file *f = do_filp_open(dfd, pathname: tmp, op: &op);
1438 if (IS_ERR(ptr: f)) {
1439 put_unused_fd(fd);
1440 fd = PTR_ERR(ptr: f);
1441 } else {
1442 fd_install(fd, file: f);
1443 }
1444 }
1445 putname(name: tmp);
1446 return fd;
1447}
1448
1449int do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1450{
1451 struct open_how how = build_open_how(flags, mode);
1452 return do_sys_openat2(dfd, filename, how: &how);
1453}
1454
1455
1456SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1457{
1458 if (force_o_largefile())
1459 flags |= O_LARGEFILE;
1460 return do_sys_open(AT_FDCWD, filename, flags, mode);
1461}
1462
1463SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1464 umode_t, mode)
1465{
1466 if (force_o_largefile())
1467 flags |= O_LARGEFILE;
1468 return do_sys_open(dfd, filename, flags, mode);
1469}
1470
1471SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1472 struct open_how __user *, how, size_t, usize)
1473{
1474 int err;
1475 struct open_how tmp;
1476
1477 BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1478 BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1479
1480 if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1481 return -EINVAL;
1482 if (unlikely(usize > PAGE_SIZE))
1483 return -E2BIG;
1484
1485 err = copy_struct_from_user(dst: &tmp, ksize: sizeof(tmp), src: how, usize);
1486 if (err)
1487 return err;
1488
1489 audit_openat2_how(how: &tmp);
1490
1491 /* O_LARGEFILE is only allowed for non-O_PATH. */
1492 if (!(tmp.flags & O_PATH) && force_o_largefile())
1493 tmp.flags |= O_LARGEFILE;
1494
1495 return do_sys_openat2(dfd, filename, how: &tmp);
1496}
1497
1498#ifdef CONFIG_COMPAT
1499/*
1500 * Exactly like sys_open(), except that it doesn't set the
1501 * O_LARGEFILE flag.
1502 */
1503COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1504{
1505 return do_sys_open(AT_FDCWD, filename, flags, mode);
1506}
1507
1508/*
1509 * Exactly like sys_openat(), except that it doesn't set the
1510 * O_LARGEFILE flag.
1511 */
1512COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1513{
1514 return do_sys_open(dfd, filename, flags, mode);
1515}
1516#endif
1517
1518#ifndef __alpha__
1519
1520/*
1521 * For backward compatibility? Maybe this should be moved
1522 * into arch/i386 instead?
1523 */
1524SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1525{
1526 int flags = O_CREAT | O_WRONLY | O_TRUNC;
1527
1528 if (force_o_largefile())
1529 flags |= O_LARGEFILE;
1530 return do_sys_open(AT_FDCWD, filename: pathname, flags, mode);
1531}
1532#endif
1533
1534/*
1535 * "id" is the POSIX thread ID. We use the
1536 * files pointer for this..
1537 */
1538static int filp_flush(struct file *filp, fl_owner_t id)
1539{
1540 int retval = 0;
1541
1542 if (CHECK_DATA_CORRUPTION(file_count(filp) == 0, filp,
1543 "VFS: Close: file count is 0 (f_op=%ps)",
1544 filp->f_op)) {
1545 return 0;
1546 }
1547
1548 if (filp->f_op->flush)
1549 retval = filp->f_op->flush(filp, id);
1550
1551 if (likely(!(filp->f_mode & FMODE_PATH))) {
1552 dnotify_flush(filp, id);
1553 locks_remove_posix(filp, id);
1554 }
1555 return retval;
1556}
1557
1558int filp_close(struct file *filp, fl_owner_t id)
1559{
1560 int retval;
1561
1562 retval = filp_flush(filp, id);
1563 fput_close(filp);
1564
1565 return retval;
1566}
1567EXPORT_SYMBOL(filp_close);
1568
1569/*
1570 * Careful here! We test whether the file pointer is NULL before
1571 * releasing the fd. This ensures that one clone task can't release
1572 * an fd while another clone is opening it.
1573 */
1574SYSCALL_DEFINE1(close, unsigned int, fd)
1575{
1576 int retval;
1577 struct file *file;
1578
1579 file = file_close_fd(fd);
1580 if (!file)
1581 return -EBADF;
1582
1583 retval = filp_flush(filp: file, current->files);
1584
1585 /*
1586 * We're returning to user space. Don't bother
1587 * with any delayed fput() cases.
1588 */
1589 fput_close_sync(file);
1590
1591 if (likely(retval == 0))
1592 return 0;
1593
1594 /* can't restart close syscall because file table entry was cleared */
1595 if (retval == -ERESTARTSYS ||
1596 retval == -ERESTARTNOINTR ||
1597 retval == -ERESTARTNOHAND ||
1598 retval == -ERESTART_RESTARTBLOCK)
1599 retval = -EINTR;
1600
1601 return retval;
1602}
1603
1604/*
1605 * This routine simulates a hangup on the tty, to arrange that users
1606 * are given clean terminals at login time.
1607 */
1608SYSCALL_DEFINE0(vhangup)
1609{
1610 if (capable(CAP_SYS_TTY_CONFIG)) {
1611 tty_vhangup_self();
1612 return 0;
1613 }
1614 return -EPERM;
1615}
1616
1617/*
1618 * Called when an inode is about to be open.
1619 * We use this to disallow opening large files on 32bit systems if
1620 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1621 * on this flag in sys_open.
1622 */
1623int generic_file_open(struct inode * inode, struct file * filp)
1624{
1625 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1626 return -EOVERFLOW;
1627 return 0;
1628}
1629
1630EXPORT_SYMBOL(generic_file_open);
1631
1632/*
1633 * This is used by subsystems that don't want seekable
1634 * file descriptors. The function is not supposed to ever fail, the only
1635 * reason it returns an 'int' and not 'void' is so that it can be plugged
1636 * directly into file_operations structure.
1637 */
1638int nonseekable_open(struct inode *inode, struct file *filp)
1639{
1640 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1641 return 0;
1642}
1643
1644EXPORT_SYMBOL(nonseekable_open);
1645
1646/*
1647 * stream_open is used by subsystems that want stream-like file descriptors.
1648 * Such file descriptors are not seekable and don't have notion of position
1649 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1650 * Contrary to file descriptors of other regular files, .read() and .write()
1651 * can run simultaneously.
1652 *
1653 * stream_open never fails and is marked to return int so that it could be
1654 * directly used as file_operations.open .
1655 */
1656int stream_open(struct inode *inode, struct file *filp)
1657{
1658 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1659 filp->f_mode |= FMODE_STREAM;
1660 return 0;
1661}
1662
1663EXPORT_SYMBOL(stream_open);
1664

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source code of linux/fs/open.c