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