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