1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * linux/fs/open.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8 #include <linux/string.h>
9 #include <linux/mm.h>
10 #include <linux/file.h>
11 #include <linux/fdtable.h>
12 #include <linux/fsnotify.h>
13 #include <linux/module.h>
14 #include <linux/tty.h>
15 #include <linux/namei.h>
16 #include <linux/backing-dev.h>
17 #include <linux/capability.h>
18 #include <linux/securebits.h>
19 #include <linux/security.h>
20 #include <linux/mount.h>
21 #include <linux/fcntl.h>
22 #include <linux/slab.h>
23 #include <linux/uaccess.h>
24 #include <linux/fs.h>
25 #include <linux/personality.h>
26 #include <linux/pagemap.h>
27 #include <linux/syscalls.h>
28 #include <linux/rcupdate.h>
29 #include <linux/audit.h>
30 #include <linux/falloc.h>
31 #include <linux/fs_struct.h>
32 #include <linux/dnotify.h>
33 #include <linux/compat.h>
34 #include <linux/mnt_idmapping.h>
35 #include <linux/filelock.h>
36
37 #include "internal.h"
38
do_truncate(struct mnt_idmap * idmap,struct dentry * dentry,loff_t length,unsigned int time_attrs,struct file * filp)39 int do_truncate(struct mnt_idmap *idmap, struct dentry *dentry,
40 loff_t length, unsigned int time_attrs, struct file *filp)
41 {
42 int ret;
43 struct iattr newattrs;
44
45 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
46 if (length < 0)
47 return -EINVAL;
48
49 newattrs.ia_size = length;
50 newattrs.ia_valid = ATTR_SIZE | time_attrs;
51 if (filp) {
52 newattrs.ia_file = filp;
53 newattrs.ia_valid |= ATTR_FILE;
54 }
55
56 /* Remove suid, sgid, and file capabilities on truncate too */
57 ret = dentry_needs_remove_privs(idmap, dentry);
58 if (ret < 0)
59 return ret;
60 if (ret)
61 newattrs.ia_valid |= ret | ATTR_FORCE;
62
63 inode_lock(dentry->d_inode);
64 /* Note any delegations or leases have already been broken: */
65 ret = notify_change(idmap, dentry, &newattrs, NULL);
66 inode_unlock(dentry->d_inode);
67 return ret;
68 }
69
vfs_truncate(const struct path * path,loff_t length)70 long vfs_truncate(const struct path *path, loff_t length)
71 {
72 struct mnt_idmap *idmap;
73 struct inode *inode;
74 long error;
75
76 inode = path->dentry->d_inode;
77
78 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
79 if (S_ISDIR(inode->i_mode))
80 return -EISDIR;
81 if (!S_ISREG(inode->i_mode))
82 return -EINVAL;
83
84 idmap = mnt_idmap(path->mnt);
85 error = inode_permission(idmap, inode, MAY_WRITE);
86 if (error)
87 return error;
88
89 error = fsnotify_truncate_perm(path, length);
90 if (error)
91 return error;
92
93 error = mnt_want_write(path->mnt);
94 if (error)
95 return error;
96
97 error = -EPERM;
98 if (IS_APPEND(inode))
99 goto mnt_drop_write_and_out;
100
101 error = get_write_access(inode);
102 if (error)
103 goto mnt_drop_write_and_out;
104
105 /*
106 * Make sure that there are no leases. get_write_access() protects
107 * against the truncate racing with a lease-granting setlease().
108 */
109 error = break_lease(inode, O_WRONLY);
110 if (error)
111 goto put_write_and_out;
112
113 error = security_path_truncate(path);
114 if (!error)
115 error = do_truncate(idmap, path->dentry, length, 0, NULL);
116
117 put_write_and_out:
118 put_write_access(inode);
119 mnt_drop_write_and_out:
120 mnt_drop_write(path->mnt);
121
122 return error;
123 }
124 EXPORT_SYMBOL_GPL(vfs_truncate);
125
do_sys_truncate(const char __user * pathname,loff_t length)126 long do_sys_truncate(const char __user *pathname, loff_t length)
127 {
128 unsigned int lookup_flags = LOOKUP_FOLLOW;
129 struct path path;
130 int error;
131
132 if (length < 0) /* sorry, but loff_t says... */
133 return -EINVAL;
134
135 retry:
136 error = user_path_at(AT_FDCWD, pathname, lookup_flags, &path);
137 if (!error) {
138 error = vfs_truncate(&path, length);
139 path_put(&path);
140 }
141 if (retry_estale(error, lookup_flags)) {
142 lookup_flags |= LOOKUP_REVAL;
143 goto retry;
144 }
145 return error;
146 }
147
SYSCALL_DEFINE2(truncate,const char __user *,path,long,length)148 SYSCALL_DEFINE2(truncate, const char __user *, path, long, length)
149 {
150 return do_sys_truncate(path, length);
151 }
152
153 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(truncate,const char __user *,path,compat_off_t,length)154 COMPAT_SYSCALL_DEFINE2(truncate, const char __user *, path, compat_off_t, length)
155 {
156 return do_sys_truncate(path, length);
157 }
158 #endif
159
do_ftruncate(struct file * file,loff_t length,int small)160 long do_ftruncate(struct file *file, loff_t length, int small)
161 {
162 struct inode *inode;
163 struct dentry *dentry;
164 int error;
165
166 /* explicitly opened as large or we are on 64-bit box */
167 if (file->f_flags & O_LARGEFILE)
168 small = 0;
169
170 dentry = file->f_path.dentry;
171 inode = dentry->d_inode;
172 if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
173 return -EINVAL;
174
175 /* Cannot ftruncate over 2^31 bytes without large file support */
176 if (small && length > MAX_NON_LFS)
177 return -EINVAL;
178
179 /* Check IS_APPEND on real upper inode */
180 if (IS_APPEND(file_inode(file)))
181 return -EPERM;
182
183 error = security_file_truncate(file);
184 if (error)
185 return error;
186
187 error = fsnotify_truncate_perm(&file->f_path, length);
188 if (error)
189 return error;
190
191 sb_start_write(inode->i_sb);
192 error = do_truncate(file_mnt_idmap(file), dentry, length,
193 ATTR_MTIME | ATTR_CTIME, file);
194 sb_end_write(inode->i_sb);
195
196 return error;
197 }
198
do_sys_ftruncate(unsigned int fd,loff_t length,int small)199 long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
200 {
201 if (length < 0)
202 return -EINVAL;
203 CLASS(fd, f)(fd);
204 if (fd_empty(f))
205 return -EBADF;
206
207 return do_ftruncate(fd_file(f), length, small);
208 }
209
SYSCALL_DEFINE2(ftruncate,unsigned int,fd,off_t,length)210 SYSCALL_DEFINE2(ftruncate, unsigned int, fd, off_t, length)
211 {
212 return do_sys_ftruncate(fd, length, 1);
213 }
214
215 #ifdef CONFIG_COMPAT
COMPAT_SYSCALL_DEFINE2(ftruncate,unsigned int,fd,compat_off_t,length)216 COMPAT_SYSCALL_DEFINE2(ftruncate, unsigned int, fd, compat_off_t, length)
217 {
218 return do_sys_ftruncate(fd, length, 1);
219 }
220 #endif
221
222 /* LFS versions of truncate are only needed on 32 bit machines */
223 #if BITS_PER_LONG == 32
SYSCALL_DEFINE2(truncate64,const char __user *,path,loff_t,length)224 SYSCALL_DEFINE2(truncate64, const char __user *, path, loff_t, length)
225 {
226 return do_sys_truncate(path, length);
227 }
228
SYSCALL_DEFINE2(ftruncate64,unsigned int,fd,loff_t,length)229 SYSCALL_DEFINE2(ftruncate64, unsigned int, fd, loff_t, length)
230 {
231 return do_sys_ftruncate(fd, length, 0);
232 }
233 #endif /* BITS_PER_LONG == 32 */
234
235 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_TRUNCATE64)
COMPAT_SYSCALL_DEFINE3(truncate64,const char __user *,pathname,compat_arg_u64_dual (length))236 COMPAT_SYSCALL_DEFINE3(truncate64, const char __user *, pathname,
237 compat_arg_u64_dual(length))
238 {
239 return ksys_truncate(pathname, compat_arg_u64_glue(length));
240 }
241 #endif
242
243 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FTRUNCATE64)
COMPAT_SYSCALL_DEFINE3(ftruncate64,unsigned int,fd,compat_arg_u64_dual (length))244 COMPAT_SYSCALL_DEFINE3(ftruncate64, unsigned int, fd,
245 compat_arg_u64_dual(length))
246 {
247 return ksys_ftruncate(fd, compat_arg_u64_glue(length));
248 }
249 #endif
250
vfs_fallocate(struct file * file,int mode,loff_t offset,loff_t len)251 int vfs_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
252 {
253 struct inode *inode = file_inode(file);
254 long ret;
255 loff_t sum;
256
257 if (offset < 0 || len <= 0)
258 return -EINVAL;
259
260 if (mode & ~(FALLOC_FL_MODE_MASK | FALLOC_FL_KEEP_SIZE))
261 return -EOPNOTSUPP;
262
263 /*
264 * Modes are exclusive, even if that is not obvious from the encoding
265 * as bit masks and the mix with the flag in the same namespace.
266 *
267 * To make things even more complicated, FALLOC_FL_ALLOCATE_RANGE is
268 * encoded as no bit set.
269 */
270 switch (mode & FALLOC_FL_MODE_MASK) {
271 case FALLOC_FL_ALLOCATE_RANGE:
272 case FALLOC_FL_UNSHARE_RANGE:
273 case FALLOC_FL_ZERO_RANGE:
274 break;
275 case FALLOC_FL_PUNCH_HOLE:
276 if (!(mode & FALLOC_FL_KEEP_SIZE))
277 return -EOPNOTSUPP;
278 break;
279 case FALLOC_FL_COLLAPSE_RANGE:
280 case FALLOC_FL_INSERT_RANGE:
281 if (mode & FALLOC_FL_KEEP_SIZE)
282 return -EOPNOTSUPP;
283 break;
284 default:
285 return -EOPNOTSUPP;
286 }
287
288 if (!(file->f_mode & FMODE_WRITE))
289 return -EBADF;
290
291 /*
292 * On append-only files only space preallocation is supported.
293 */
294 if ((mode & ~FALLOC_FL_KEEP_SIZE) && IS_APPEND(inode))
295 return -EPERM;
296
297 if (IS_IMMUTABLE(inode))
298 return -EPERM;
299
300 /*
301 * We cannot allow any fallocate operation on an active swapfile
302 */
303 if (IS_SWAPFILE(inode))
304 return -ETXTBSY;
305
306 /*
307 * Revalidate the write permissions, in case security policy has
308 * changed since the files were opened.
309 */
310 ret = security_file_permission(file, MAY_WRITE);
311 if (ret)
312 return ret;
313
314 ret = fsnotify_file_area_perm(file, MAY_WRITE, &offset, len);
315 if (ret)
316 return ret;
317
318 if (S_ISFIFO(inode->i_mode))
319 return -ESPIPE;
320
321 if (S_ISDIR(inode->i_mode))
322 return -EISDIR;
323
324 if (!S_ISREG(inode->i_mode) && !S_ISBLK(inode->i_mode))
325 return -ENODEV;
326
327 /* Check for wraparound */
328 if (check_add_overflow(offset, len, &sum))
329 return -EFBIG;
330
331 if (sum > inode->i_sb->s_maxbytes)
332 return -EFBIG;
333
334 if (!file->f_op->fallocate)
335 return -EOPNOTSUPP;
336
337 file_start_write(file);
338 ret = file->f_op->fallocate(file, mode, offset, len);
339
340 /*
341 * Create inotify and fanotify events.
342 *
343 * To keep the logic simple always create events if fallocate succeeds.
344 * This implies that events are even created if the file size remains
345 * unchanged, e.g. when using flag FALLOC_FL_KEEP_SIZE.
346 */
347 if (ret == 0)
348 fsnotify_modify(file);
349
350 file_end_write(file);
351 return ret;
352 }
353 EXPORT_SYMBOL_GPL(vfs_fallocate);
354
ksys_fallocate(int fd,int mode,loff_t offset,loff_t len)355 int ksys_fallocate(int fd, int mode, loff_t offset, loff_t len)
356 {
357 CLASS(fd, f)(fd);
358
359 if (fd_empty(f))
360 return -EBADF;
361
362 return vfs_fallocate(fd_file(f), mode, offset, len);
363 }
364
SYSCALL_DEFINE4(fallocate,int,fd,int,mode,loff_t,offset,loff_t,len)365 SYSCALL_DEFINE4(fallocate, int, fd, int, mode, loff_t, offset, loff_t, len)
366 {
367 return ksys_fallocate(fd, mode, offset, len);
368 }
369
370 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FALLOCATE)
COMPAT_SYSCALL_DEFINE6(fallocate,int,fd,int,mode,compat_arg_u64_dual (offset),compat_arg_u64_dual (len))371 COMPAT_SYSCALL_DEFINE6(fallocate, int, fd, int, mode, compat_arg_u64_dual(offset),
372 compat_arg_u64_dual(len))
373 {
374 return ksys_fallocate(fd, mode, compat_arg_u64_glue(offset),
375 compat_arg_u64_glue(len));
376 }
377 #endif
378
379 /*
380 * access() needs to use the real uid/gid, not the effective uid/gid.
381 * We do this by temporarily clearing all FS-related capabilities and
382 * switching the fsuid/fsgid around to the real ones.
383 *
384 * Creating new credentials is expensive, so we try to skip doing it,
385 * which we can if the result would match what we already got.
386 */
access_need_override_creds(int flags)387 static bool access_need_override_creds(int flags)
388 {
389 const struct cred *cred;
390
391 if (flags & AT_EACCESS)
392 return false;
393
394 cred = current_cred();
395 if (!uid_eq(cred->fsuid, cred->uid) ||
396 !gid_eq(cred->fsgid, cred->gid))
397 return true;
398
399 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
400 kuid_t root_uid = make_kuid(cred->user_ns, 0);
401 if (!uid_eq(cred->uid, root_uid)) {
402 if (!cap_isclear(cred->cap_effective))
403 return true;
404 } else {
405 if (!cap_isidentical(cred->cap_effective,
406 cred->cap_permitted))
407 return true;
408 }
409 }
410
411 return false;
412 }
413
access_override_creds(void)414 static const struct cred *access_override_creds(void)
415 {
416 struct cred *override_cred;
417
418 override_cred = prepare_creds();
419 if (!override_cred)
420 return NULL;
421
422 /*
423 * XXX access_need_override_creds performs checks in hopes of skipping
424 * this work. Make sure it stays in sync if making any changes in this
425 * routine.
426 */
427
428 override_cred->fsuid = override_cred->uid;
429 override_cred->fsgid = override_cred->gid;
430
431 if (!issecure(SECURE_NO_SETUID_FIXUP)) {
432 /* Clear the capabilities if we switch to a non-root user */
433 kuid_t root_uid = make_kuid(override_cred->user_ns, 0);
434 if (!uid_eq(override_cred->uid, root_uid))
435 cap_clear(override_cred->cap_effective);
436 else
437 override_cred->cap_effective =
438 override_cred->cap_permitted;
439 }
440
441 /*
442 * The new set of credentials can *only* be used in
443 * task-synchronous circumstances, and does not need
444 * RCU freeing, unless somebody then takes a separate
445 * reference to it.
446 *
447 * NOTE! This is _only_ true because this credential
448 * is used purely for override_creds() that installs
449 * it as the subjective cred. Other threads will be
450 * accessing ->real_cred, not the subjective cred.
451 *
452 * If somebody _does_ make a copy of this (using the
453 * 'get_current_cred()' function), that will clear the
454 * non_rcu field, because now that other user may be
455 * expecting RCU freeing. But normal thread-synchronous
456 * cred accesses will keep things non-racy to avoid RCU
457 * freeing.
458 */
459 override_cred->non_rcu = 1;
460 return override_creds(override_cred);
461 }
462
do_faccessat(int dfd,const char __user * filename,int mode,int flags)463 static long do_faccessat(int dfd, const char __user *filename, int mode, int flags)
464 {
465 struct path path;
466 struct inode *inode;
467 int res;
468 unsigned int lookup_flags = LOOKUP_FOLLOW;
469 const struct cred *old_cred = NULL;
470
471 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
472 return -EINVAL;
473
474 if (flags & ~(AT_EACCESS | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH))
475 return -EINVAL;
476
477 if (flags & AT_SYMLINK_NOFOLLOW)
478 lookup_flags &= ~LOOKUP_FOLLOW;
479 if (flags & AT_EMPTY_PATH)
480 lookup_flags |= LOOKUP_EMPTY;
481
482 if (access_need_override_creds(flags)) {
483 old_cred = access_override_creds();
484 if (!old_cred)
485 return -ENOMEM;
486 }
487
488 retry:
489 res = user_path_at(dfd, filename, lookup_flags, &path);
490 if (res)
491 goto out;
492
493 inode = d_backing_inode(path.dentry);
494
495 if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) {
496 /*
497 * MAY_EXEC on regular files is denied if the fs is mounted
498 * with the "noexec" flag.
499 */
500 res = -EACCES;
501 if (path_noexec(&path))
502 goto out_path_release;
503 }
504
505 res = inode_permission(mnt_idmap(path.mnt), inode, mode | MAY_ACCESS);
506 /* SuS v2 requires we report a read only fs too */
507 if (res || !(mode & S_IWOTH) || special_file(inode->i_mode))
508 goto out_path_release;
509 /*
510 * This is a rare case where using __mnt_is_readonly()
511 * is OK without a mnt_want/drop_write() pair. Since
512 * no actual write to the fs is performed here, we do
513 * not need to telegraph to that to anyone.
514 *
515 * By doing this, we accept that this access is
516 * inherently racy and know that the fs may change
517 * state before we even see this result.
518 */
519 if (__mnt_is_readonly(path.mnt))
520 res = -EROFS;
521
522 out_path_release:
523 path_put(&path);
524 if (retry_estale(res, lookup_flags)) {
525 lookup_flags |= LOOKUP_REVAL;
526 goto retry;
527 }
528 out:
529 if (old_cred)
530 put_cred(revert_creds(old_cred));
531
532 return res;
533 }
534
SYSCALL_DEFINE3(faccessat,int,dfd,const char __user *,filename,int,mode)535 SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode)
536 {
537 return do_faccessat(dfd, filename, mode, 0);
538 }
539
SYSCALL_DEFINE4(faccessat2,int,dfd,const char __user *,filename,int,mode,int,flags)540 SYSCALL_DEFINE4(faccessat2, int, dfd, const char __user *, filename, int, mode,
541 int, flags)
542 {
543 return do_faccessat(dfd, filename, mode, flags);
544 }
545
SYSCALL_DEFINE2(access,const char __user *,filename,int,mode)546 SYSCALL_DEFINE2(access, const char __user *, filename, int, mode)
547 {
548 return do_faccessat(AT_FDCWD, filename, mode, 0);
549 }
550
SYSCALL_DEFINE1(chdir,const char __user *,filename)551 SYSCALL_DEFINE1(chdir, const char __user *, filename)
552 {
553 struct path path;
554 int error;
555 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
556 retry:
557 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
558 if (error)
559 goto out;
560
561 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
562 if (error)
563 goto dput_and_out;
564
565 set_fs_pwd(current->fs, &path);
566
567 dput_and_out:
568 path_put(&path);
569 if (retry_estale(error, lookup_flags)) {
570 lookup_flags |= LOOKUP_REVAL;
571 goto retry;
572 }
573 out:
574 return error;
575 }
576
SYSCALL_DEFINE1(fchdir,unsigned int,fd)577 SYSCALL_DEFINE1(fchdir, unsigned int, fd)
578 {
579 CLASS(fd_raw, f)(fd);
580 int error;
581
582 if (fd_empty(f))
583 return -EBADF;
584
585 if (!d_can_lookup(fd_file(f)->f_path.dentry))
586 return -ENOTDIR;
587
588 error = file_permission(fd_file(f), MAY_EXEC | MAY_CHDIR);
589 if (!error)
590 set_fs_pwd(current->fs, &fd_file(f)->f_path);
591 return error;
592 }
593
SYSCALL_DEFINE1(chroot,const char __user *,filename)594 SYSCALL_DEFINE1(chroot, const char __user *, filename)
595 {
596 struct path path;
597 int error;
598 unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_DIRECTORY;
599 retry:
600 error = user_path_at(AT_FDCWD, filename, lookup_flags, &path);
601 if (error)
602 goto out;
603
604 error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
605 if (error)
606 goto dput_and_out;
607
608 error = -EPERM;
609 if (!ns_capable(current_user_ns(), CAP_SYS_CHROOT))
610 goto dput_and_out;
611 error = security_path_chroot(&path);
612 if (error)
613 goto dput_and_out;
614
615 set_fs_root(current->fs, &path);
616 error = 0;
617 dput_and_out:
618 path_put(&path);
619 if (retry_estale(error, lookup_flags)) {
620 lookup_flags |= LOOKUP_REVAL;
621 goto retry;
622 }
623 out:
624 return error;
625 }
626
chmod_common(const struct path * path,umode_t mode)627 int chmod_common(const struct path *path, umode_t mode)
628 {
629 struct inode *inode = path->dentry->d_inode;
630 struct inode *delegated_inode = NULL;
631 struct iattr newattrs;
632 int error;
633
634 error = mnt_want_write(path->mnt);
635 if (error)
636 return error;
637 retry_deleg:
638 inode_lock(inode);
639 error = security_path_chmod(path, mode);
640 if (error)
641 goto out_unlock;
642 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
643 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
644 error = notify_change(mnt_idmap(path->mnt), path->dentry,
645 &newattrs, &delegated_inode);
646 out_unlock:
647 inode_unlock(inode);
648 if (delegated_inode) {
649 error = break_deleg_wait(&delegated_inode);
650 if (!error)
651 goto retry_deleg;
652 }
653 mnt_drop_write(path->mnt);
654 return error;
655 }
656
vfs_fchmod(struct file * file,umode_t mode)657 int vfs_fchmod(struct file *file, umode_t mode)
658 {
659 audit_file(file);
660 return chmod_common(&file->f_path, mode);
661 }
662
SYSCALL_DEFINE2(fchmod,unsigned int,fd,umode_t,mode)663 SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
664 {
665 CLASS(fd, f)(fd);
666
667 if (fd_empty(f))
668 return -EBADF;
669
670 return vfs_fchmod(fd_file(f), mode);
671 }
672
do_fchmodat(int dfd,const char __user * filename,umode_t mode,unsigned int flags)673 static int do_fchmodat(int dfd, const char __user *filename, umode_t mode,
674 unsigned int flags)
675 {
676 struct path path;
677 int error;
678 unsigned int lookup_flags;
679
680 if (unlikely(flags & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)))
681 return -EINVAL;
682
683 lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
684 if (flags & AT_EMPTY_PATH)
685 lookup_flags |= LOOKUP_EMPTY;
686
687 retry:
688 error = user_path_at(dfd, filename, lookup_flags, &path);
689 if (!error) {
690 error = chmod_common(&path, mode);
691 path_put(&path);
692 if (retry_estale(error, lookup_flags)) {
693 lookup_flags |= LOOKUP_REVAL;
694 goto retry;
695 }
696 }
697 return error;
698 }
699
SYSCALL_DEFINE4(fchmodat2,int,dfd,const char __user *,filename,umode_t,mode,unsigned int,flags)700 SYSCALL_DEFINE4(fchmodat2, int, dfd, const char __user *, filename,
701 umode_t, mode, unsigned int, flags)
702 {
703 return do_fchmodat(dfd, filename, mode, flags);
704 }
705
SYSCALL_DEFINE3(fchmodat,int,dfd,const char __user *,filename,umode_t,mode)706 SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
707 umode_t, mode)
708 {
709 return do_fchmodat(dfd, filename, mode, 0);
710 }
711
SYSCALL_DEFINE2(chmod,const char __user *,filename,umode_t,mode)712 SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
713 {
714 return do_fchmodat(AT_FDCWD, filename, mode, 0);
715 }
716
717 /*
718 * Check whether @kuid is valid and if so generate and set vfsuid_t in
719 * ia_vfsuid.
720 *
721 * Return: true if @kuid is valid, false if not.
722 */
setattr_vfsuid(struct iattr * attr,kuid_t kuid)723 static inline bool setattr_vfsuid(struct iattr *attr, kuid_t kuid)
724 {
725 if (!uid_valid(kuid))
726 return false;
727 attr->ia_valid |= ATTR_UID;
728 attr->ia_vfsuid = VFSUIDT_INIT(kuid);
729 return true;
730 }
731
732 /*
733 * Check whether @kgid is valid and if so generate and set vfsgid_t in
734 * ia_vfsgid.
735 *
736 * Return: true if @kgid is valid, false if not.
737 */
setattr_vfsgid(struct iattr * attr,kgid_t kgid)738 static inline bool setattr_vfsgid(struct iattr *attr, kgid_t kgid)
739 {
740 if (!gid_valid(kgid))
741 return false;
742 attr->ia_valid |= ATTR_GID;
743 attr->ia_vfsgid = VFSGIDT_INIT(kgid);
744 return true;
745 }
746
chown_common(const struct path * path,uid_t user,gid_t group)747 int chown_common(const struct path *path, uid_t user, gid_t group)
748 {
749 struct mnt_idmap *idmap;
750 struct user_namespace *fs_userns;
751 struct inode *inode = path->dentry->d_inode;
752 struct inode *delegated_inode = NULL;
753 int error;
754 struct iattr newattrs;
755 kuid_t uid;
756 kgid_t gid;
757
758 uid = make_kuid(current_user_ns(), user);
759 gid = make_kgid(current_user_ns(), group);
760
761 idmap = mnt_idmap(path->mnt);
762 fs_userns = i_user_ns(inode);
763
764 retry_deleg:
765 newattrs.ia_vfsuid = INVALID_VFSUID;
766 newattrs.ia_vfsgid = INVALID_VFSGID;
767 newattrs.ia_valid = ATTR_CTIME;
768 if ((user != (uid_t)-1) && !setattr_vfsuid(&newattrs, uid))
769 return -EINVAL;
770 if ((group != (gid_t)-1) && !setattr_vfsgid(&newattrs, gid))
771 return -EINVAL;
772 inode_lock(inode);
773 if (!S_ISDIR(inode->i_mode))
774 newattrs.ia_valid |= ATTR_KILL_SUID | ATTR_KILL_PRIV |
775 setattr_should_drop_sgid(idmap, inode);
776 /* Continue to send actual fs values, not the mount values. */
777 error = security_path_chown(
778 path,
779 from_vfsuid(idmap, fs_userns, newattrs.ia_vfsuid),
780 from_vfsgid(idmap, fs_userns, newattrs.ia_vfsgid));
781 if (!error)
782 error = notify_change(idmap, path->dentry, &newattrs,
783 &delegated_inode);
784 inode_unlock(inode);
785 if (delegated_inode) {
786 error = break_deleg_wait(&delegated_inode);
787 if (!error)
788 goto retry_deleg;
789 }
790 return error;
791 }
792
do_fchownat(int dfd,const char __user * filename,uid_t user,gid_t group,int flag)793 int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
794 int flag)
795 {
796 struct path path;
797 int error = -EINVAL;
798 int lookup_flags;
799
800 if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0)
801 goto out;
802
803 lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
804 if (flag & AT_EMPTY_PATH)
805 lookup_flags |= LOOKUP_EMPTY;
806 retry:
807 error = user_path_at(dfd, filename, lookup_flags, &path);
808 if (error)
809 goto out;
810 error = mnt_want_write(path.mnt);
811 if (error)
812 goto out_release;
813 error = chown_common(&path, user, group);
814 mnt_drop_write(path.mnt);
815 out_release:
816 path_put(&path);
817 if (retry_estale(error, lookup_flags)) {
818 lookup_flags |= LOOKUP_REVAL;
819 goto retry;
820 }
821 out:
822 return error;
823 }
824
SYSCALL_DEFINE5(fchownat,int,dfd,const char __user *,filename,uid_t,user,gid_t,group,int,flag)825 SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
826 gid_t, group, int, flag)
827 {
828 return do_fchownat(dfd, filename, user, group, flag);
829 }
830
SYSCALL_DEFINE3(chown,const char __user *,filename,uid_t,user,gid_t,group)831 SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
832 {
833 return do_fchownat(AT_FDCWD, filename, user, group, 0);
834 }
835
SYSCALL_DEFINE3(lchown,const char __user *,filename,uid_t,user,gid_t,group)836 SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
837 {
838 return do_fchownat(AT_FDCWD, filename, user, group,
839 AT_SYMLINK_NOFOLLOW);
840 }
841
vfs_fchown(struct file * file,uid_t user,gid_t group)842 int vfs_fchown(struct file *file, uid_t user, gid_t group)
843 {
844 int error;
845
846 error = mnt_want_write_file(file);
847 if (error)
848 return error;
849 audit_file(file);
850 error = chown_common(&file->f_path, user, group);
851 mnt_drop_write_file(file);
852 return error;
853 }
854
ksys_fchown(unsigned int fd,uid_t user,gid_t group)855 int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
856 {
857 CLASS(fd, f)(fd);
858
859 if (fd_empty(f))
860 return -EBADF;
861
862 return vfs_fchown(fd_file(f), user, group);
863 }
864
SYSCALL_DEFINE3(fchown,unsigned int,fd,uid_t,user,gid_t,group)865 SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
866 {
867 return ksys_fchown(fd, user, group);
868 }
869
file_get_write_access(struct file * f)870 static inline int file_get_write_access(struct file *f)
871 {
872 int error;
873
874 error = get_write_access(f->f_inode);
875 if (unlikely(error))
876 return error;
877 error = mnt_get_write_access(f->f_path.mnt);
878 if (unlikely(error))
879 goto cleanup_inode;
880 if (unlikely(f->f_mode & FMODE_BACKING)) {
881 error = mnt_get_write_access(backing_file_user_path(f)->mnt);
882 if (unlikely(error))
883 goto cleanup_mnt;
884 }
885 return 0;
886
887 cleanup_mnt:
888 mnt_put_write_access(f->f_path.mnt);
889 cleanup_inode:
890 put_write_access(f->f_inode);
891 return error;
892 }
893
do_dentry_open(struct file * f,int (* open)(struct inode *,struct file *))894 static int do_dentry_open(struct file *f,
895 int (*open)(struct inode *, struct file *))
896 {
897 static const struct file_operations empty_fops = {};
898 struct inode *inode = f->f_path.dentry->d_inode;
899 int error;
900
901 path_get(&f->f_path);
902 f->f_inode = inode;
903 f->f_mapping = inode->i_mapping;
904 f->f_wb_err = filemap_sample_wb_err(f->f_mapping);
905 f->f_sb_err = file_sample_sb_err(f);
906
907 if (unlikely(f->f_flags & O_PATH)) {
908 f->f_mode = FMODE_PATH | FMODE_OPENED;
909 file_set_fsnotify_mode(f, FMODE_NONOTIFY);
910 f->f_op = &empty_fops;
911 return 0;
912 }
913
914 if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) {
915 i_readcount_inc(inode);
916 } else if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
917 error = file_get_write_access(f);
918 if (unlikely(error))
919 goto cleanup_file;
920 f->f_mode |= FMODE_WRITER;
921 }
922
923 /* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
924 if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
925 f->f_mode |= FMODE_ATOMIC_POS;
926
927 f->f_op = fops_get(inode->i_fop);
928 if (WARN_ON(!f->f_op)) {
929 error = -ENODEV;
930 goto cleanup_all;
931 }
932
933 error = security_file_open(f);
934 if (error)
935 goto cleanup_all;
936
937 /*
938 * Set FMODE_NONOTIFY_* bits according to existing permission watches.
939 * If FMODE_NONOTIFY mode was already set for an fanotify fd or for a
940 * pseudo file, this call will not change the mode.
941 */
942 file_set_fsnotify_mode_from_watchers(f);
943 error = fsnotify_open_perm(f);
944 if (error)
945 goto cleanup_all;
946
947 error = break_lease(file_inode(f), f->f_flags);
948 if (error)
949 goto cleanup_all;
950
951 /* normally all 3 are set; ->open() can clear them if needed */
952 f->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
953 if (!open)
954 open = f->f_op->open;
955 if (open) {
956 error = open(inode, f);
957 if (error)
958 goto cleanup_all;
959 }
960 f->f_mode |= FMODE_OPENED;
961 if ((f->f_mode & FMODE_READ) &&
962 likely(f->f_op->read || f->f_op->read_iter))
963 f->f_mode |= FMODE_CAN_READ;
964 if ((f->f_mode & FMODE_WRITE) &&
965 likely(f->f_op->write || f->f_op->write_iter))
966 f->f_mode |= FMODE_CAN_WRITE;
967 if ((f->f_mode & FMODE_LSEEK) && !f->f_op->llseek)
968 f->f_mode &= ~FMODE_LSEEK;
969 if (f->f_mapping->a_ops && f->f_mapping->a_ops->direct_IO)
970 f->f_mode |= FMODE_CAN_ODIRECT;
971
972 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
973 f->f_iocb_flags = iocb_flags(f);
974
975 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
976
977 if ((f->f_flags & O_DIRECT) && !(f->f_mode & FMODE_CAN_ODIRECT))
978 return -EINVAL;
979
980 /*
981 * XXX: Huge page cache doesn't support writing yet. Drop all page
982 * cache for this file before processing writes.
983 */
984 if (f->f_mode & FMODE_WRITE) {
985 /*
986 * Depends on full fence from get_write_access() to synchronize
987 * against collapse_file() regarding i_writecount and nr_thps
988 * updates. Ensures subsequent insertion of THPs into the page
989 * cache will fail.
990 */
991 if (filemap_nr_thps(inode->i_mapping)) {
992 struct address_space *mapping = inode->i_mapping;
993
994 filemap_invalidate_lock(inode->i_mapping);
995 /*
996 * unmap_mapping_range just need to be called once
997 * here, because the private pages is not need to be
998 * unmapped mapping (e.g. data segment of dynamic
999 * shared libraries here).
1000 */
1001 unmap_mapping_range(mapping, 0, 0, 0);
1002 truncate_inode_pages(mapping, 0);
1003 filemap_invalidate_unlock(inode->i_mapping);
1004 }
1005 }
1006
1007 return 0;
1008
1009 cleanup_all:
1010 if (WARN_ON_ONCE(error > 0))
1011 error = -EINVAL;
1012 fops_put(f->f_op);
1013 put_file_access(f);
1014 cleanup_file:
1015 path_put(&f->f_path);
1016 f->f_path.mnt = NULL;
1017 f->f_path.dentry = NULL;
1018 f->f_inode = NULL;
1019 return error;
1020 }
1021
1022 /**
1023 * finish_open - finish opening a file
1024 * @file: file pointer
1025 * @dentry: pointer to dentry
1026 * @open: open callback
1027 *
1028 * This can be used to finish opening a file passed to i_op->atomic_open().
1029 *
1030 * If the open callback is set to NULL, then the standard f_op->open()
1031 * filesystem callback is substituted.
1032 *
1033 * NB: the dentry reference is _not_ consumed. If, for example, the dentry is
1034 * the return value of d_splice_alias(), then the caller needs to perform dput()
1035 * on it after finish_open().
1036 *
1037 * Returns zero on success or -errno if the open failed.
1038 */
finish_open(struct file * file,struct dentry * dentry,int (* open)(struct inode *,struct file *))1039 int finish_open(struct file *file, struct dentry *dentry,
1040 int (*open)(struct inode *, struct file *))
1041 {
1042 BUG_ON(file->f_mode & FMODE_OPENED); /* once it's opened, it's opened */
1043
1044 file->f_path.dentry = dentry;
1045 return do_dentry_open(file, open);
1046 }
1047 EXPORT_SYMBOL(finish_open);
1048
1049 /**
1050 * finish_no_open - finish ->atomic_open() without opening the file
1051 *
1052 * @file: file pointer
1053 * @dentry: dentry or NULL (as returned from ->lookup())
1054 *
1055 * This can be used to set the result of a successful lookup in ->atomic_open().
1056 *
1057 * NB: unlike finish_open() this function does consume the dentry reference and
1058 * the caller need not dput() it.
1059 *
1060 * Returns "0" which must be the return value of ->atomic_open() after having
1061 * called this function.
1062 */
finish_no_open(struct file * file,struct dentry * dentry)1063 int finish_no_open(struct file *file, struct dentry *dentry)
1064 {
1065 file->f_path.dentry = dentry;
1066 return 0;
1067 }
1068 EXPORT_SYMBOL(finish_no_open);
1069
file_path(struct file * filp,char * buf,int buflen)1070 char *file_path(struct file *filp, char *buf, int buflen)
1071 {
1072 return d_path(&filp->f_path, buf, buflen);
1073 }
1074 EXPORT_SYMBOL(file_path);
1075
1076 /**
1077 * vfs_open - open the file at the given path
1078 * @path: path to open
1079 * @file: newly allocated file with f_flag initialized
1080 */
vfs_open(const struct path * path,struct file * file)1081 int vfs_open(const struct path *path, struct file *file)
1082 {
1083 int ret;
1084
1085 file->f_path = *path;
1086 ret = do_dentry_open(file, NULL);
1087 if (!ret) {
1088 /*
1089 * Once we return a file with FMODE_OPENED, __fput() will call
1090 * fsnotify_close(), so we need fsnotify_open() here for
1091 * symmetry.
1092 */
1093 fsnotify_open(file);
1094 }
1095 return ret;
1096 }
1097
dentry_open(const struct path * path,int flags,const struct cred * cred)1098 struct file *dentry_open(const struct path *path, int flags,
1099 const struct cred *cred)
1100 {
1101 int error;
1102 struct file *f;
1103
1104 /* We must always pass in a valid mount pointer. */
1105 BUG_ON(!path->mnt);
1106
1107 f = alloc_empty_file(flags, cred);
1108 if (!IS_ERR(f)) {
1109 error = vfs_open(path, f);
1110 if (error) {
1111 fput(f);
1112 f = ERR_PTR(error);
1113 }
1114 }
1115 return f;
1116 }
1117 EXPORT_SYMBOL(dentry_open);
1118
dentry_open_nonotify(const struct path * path,int flags,const struct cred * cred)1119 struct file *dentry_open_nonotify(const struct path *path, int flags,
1120 const struct cred *cred)
1121 {
1122 struct file *f = alloc_empty_file(flags, cred);
1123 if (!IS_ERR(f)) {
1124 int error;
1125
1126 file_set_fsnotify_mode(f, FMODE_NONOTIFY);
1127 error = vfs_open(path, f);
1128 if (error) {
1129 fput(f);
1130 f = ERR_PTR(error);
1131 }
1132 }
1133 return f;
1134 }
1135
1136 /**
1137 * dentry_create - Create and open a file
1138 * @path: path to create
1139 * @flags: O_ flags
1140 * @mode: mode bits for new file
1141 * @cred: credentials to use
1142 *
1143 * Caller must hold the parent directory's lock, and have prepared
1144 * a negative dentry, placed in @path->dentry, for the new file.
1145 *
1146 * Caller sets @path->mnt to the vfsmount of the filesystem where
1147 * the new file is to be created. The parent directory and the
1148 * negative dentry must reside on the same filesystem instance.
1149 *
1150 * On success, returns a "struct file *". Otherwise a ERR_PTR
1151 * is returned.
1152 */
dentry_create(const struct path * path,int flags,umode_t mode,const struct cred * cred)1153 struct file *dentry_create(const struct path *path, int flags, umode_t mode,
1154 const struct cred *cred)
1155 {
1156 struct file *f;
1157 int error;
1158
1159 f = alloc_empty_file(flags, cred);
1160 if (IS_ERR(f))
1161 return f;
1162
1163 error = vfs_create(mnt_idmap(path->mnt),
1164 d_inode(path->dentry->d_parent),
1165 path->dentry, mode, true);
1166 if (!error)
1167 error = vfs_open(path, f);
1168
1169 if (unlikely(error)) {
1170 fput(f);
1171 return ERR_PTR(error);
1172 }
1173 return f;
1174 }
1175 EXPORT_SYMBOL(dentry_create);
1176
1177 /**
1178 * kernel_file_open - open a file for kernel internal use
1179 * @path: path of the file to open
1180 * @flags: open flags
1181 * @cred: credentials for open
1182 *
1183 * Open a file for use by in-kernel consumers. The file is not accounted
1184 * against nr_files and must not be installed into the file descriptor
1185 * table.
1186 *
1187 * Return: Opened file on success, an error pointer on failure.
1188 */
kernel_file_open(const struct path * path,int flags,const struct cred * cred)1189 struct file *kernel_file_open(const struct path *path, int flags,
1190 const struct cred *cred)
1191 {
1192 struct file *f;
1193 int error;
1194
1195 f = alloc_empty_file_noaccount(flags, cred);
1196 if (IS_ERR(f))
1197 return f;
1198
1199 f->f_path = *path;
1200 error = do_dentry_open(f, NULL);
1201 if (error) {
1202 fput(f);
1203 return ERR_PTR(error);
1204 }
1205
1206 fsnotify_open(f);
1207 return f;
1208 }
1209 EXPORT_SYMBOL_GPL(kernel_file_open);
1210
1211 #define WILL_CREATE(flags) (flags & (O_CREAT | __O_TMPFILE))
1212 #define O_PATH_FLAGS (O_DIRECTORY | O_NOFOLLOW | O_PATH | O_CLOEXEC)
1213
build_open_how(int flags,umode_t mode)1214 inline struct open_how build_open_how(int flags, umode_t mode)
1215 {
1216 struct open_how how = {
1217 .flags = flags & VALID_OPEN_FLAGS,
1218 .mode = mode & S_IALLUGO,
1219 };
1220
1221 /* O_PATH beats everything else. */
1222 if (how.flags & O_PATH)
1223 how.flags &= O_PATH_FLAGS;
1224 /* Modes should only be set for create-like flags. */
1225 if (!WILL_CREATE(how.flags))
1226 how.mode = 0;
1227 return how;
1228 }
1229
build_open_flags(const struct open_how * how,struct open_flags * op)1230 inline int build_open_flags(const struct open_how *how, struct open_flags *op)
1231 {
1232 u64 flags = how->flags;
1233 u64 strip = O_CLOEXEC;
1234 int lookup_flags = 0;
1235 int acc_mode = ACC_MODE(flags);
1236
1237 BUILD_BUG_ON_MSG(upper_32_bits(VALID_OPEN_FLAGS),
1238 "struct open_flags doesn't yet handle flags > 32 bits");
1239
1240 /*
1241 * Strip flags that aren't relevant in determining struct open_flags.
1242 */
1243 flags &= ~strip;
1244
1245 /*
1246 * Older syscalls implicitly clear all of the invalid flags or argument
1247 * values before calling build_open_flags(), but openat2(2) checks all
1248 * of its arguments.
1249 */
1250 if (flags & ~VALID_OPEN_FLAGS)
1251 return -EINVAL;
1252 if (how->resolve & ~VALID_RESOLVE_FLAGS)
1253 return -EINVAL;
1254
1255 /* Scoping flags are mutually exclusive. */
1256 if ((how->resolve & RESOLVE_BENEATH) && (how->resolve & RESOLVE_IN_ROOT))
1257 return -EINVAL;
1258
1259 /* Deal with the mode. */
1260 if (WILL_CREATE(flags)) {
1261 if (how->mode & ~S_IALLUGO)
1262 return -EINVAL;
1263 op->mode = how->mode | S_IFREG;
1264 } else {
1265 if (how->mode != 0)
1266 return -EINVAL;
1267 op->mode = 0;
1268 }
1269
1270 /*
1271 * Block bugs where O_DIRECTORY | O_CREAT created regular files.
1272 * Note, that blocking O_DIRECTORY | O_CREAT here also protects
1273 * O_TMPFILE below which requires O_DIRECTORY being raised.
1274 */
1275 if ((flags & (O_DIRECTORY | O_CREAT)) == (O_DIRECTORY | O_CREAT))
1276 return -EINVAL;
1277
1278 /* Now handle the creative implementation of O_TMPFILE. */
1279 if (flags & __O_TMPFILE) {
1280 /*
1281 * In order to ensure programs get explicit errors when trying
1282 * to use O_TMPFILE on old kernels we enforce that O_DIRECTORY
1283 * is raised alongside __O_TMPFILE.
1284 */
1285 if (!(flags & O_DIRECTORY))
1286 return -EINVAL;
1287 if (!(acc_mode & MAY_WRITE))
1288 return -EINVAL;
1289 }
1290 if (flags & O_PATH) {
1291 /* O_PATH only permits certain other flags to be set. */
1292 if (flags & ~O_PATH_FLAGS)
1293 return -EINVAL;
1294 acc_mode = 0;
1295 }
1296
1297 /*
1298 * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only
1299 * check for O_DSYNC if the need any syncing at all we enforce it's
1300 * always set instead of having to deal with possibly weird behaviour
1301 * for malicious applications setting only __O_SYNC.
1302 */
1303 if (flags & __O_SYNC)
1304 flags |= O_DSYNC;
1305
1306 op->open_flag = flags;
1307
1308 /* O_TRUNC implies we need access checks for write permissions */
1309 if (flags & O_TRUNC)
1310 acc_mode |= MAY_WRITE;
1311
1312 /* Allow the LSM permission hook to distinguish append
1313 access from general write access. */
1314 if (flags & O_APPEND)
1315 acc_mode |= MAY_APPEND;
1316
1317 op->acc_mode = acc_mode;
1318
1319 op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN;
1320
1321 if (flags & O_CREAT) {
1322 op->intent |= LOOKUP_CREATE;
1323 if (flags & O_EXCL) {
1324 op->intent |= LOOKUP_EXCL;
1325 flags |= O_NOFOLLOW;
1326 }
1327 }
1328
1329 if (flags & O_DIRECTORY)
1330 lookup_flags |= LOOKUP_DIRECTORY;
1331 if (!(flags & O_NOFOLLOW))
1332 lookup_flags |= LOOKUP_FOLLOW;
1333
1334 if (how->resolve & RESOLVE_NO_XDEV)
1335 lookup_flags |= LOOKUP_NO_XDEV;
1336 if (how->resolve & RESOLVE_NO_MAGICLINKS)
1337 lookup_flags |= LOOKUP_NO_MAGICLINKS;
1338 if (how->resolve & RESOLVE_NO_SYMLINKS)
1339 lookup_flags |= LOOKUP_NO_SYMLINKS;
1340 if (how->resolve & RESOLVE_BENEATH)
1341 lookup_flags |= LOOKUP_BENEATH;
1342 if (how->resolve & RESOLVE_IN_ROOT)
1343 lookup_flags |= LOOKUP_IN_ROOT;
1344 if (how->resolve & RESOLVE_CACHED) {
1345 /* Don't bother even trying for create/truncate/tmpfile open */
1346 if (flags & (O_TRUNC | O_CREAT | __O_TMPFILE))
1347 return -EAGAIN;
1348 lookup_flags |= LOOKUP_CACHED;
1349 }
1350
1351 op->lookup_flags = lookup_flags;
1352 return 0;
1353 }
1354
1355 /**
1356 * file_open_name - open file and return file pointer
1357 *
1358 * @name: struct filename containing path to open
1359 * @flags: open flags as per the open(2) second argument
1360 * @mode: mode for the new file if O_CREAT is set, else ignored
1361 *
1362 * This is the helper to open a file from kernelspace if you really
1363 * have to. But in generally you should not do this, so please move
1364 * along, nothing to see here..
1365 */
file_open_name(struct filename * name,int flags,umode_t mode)1366 struct file *file_open_name(struct filename *name, int flags, umode_t mode)
1367 {
1368 struct open_flags op;
1369 struct open_how how = build_open_how(flags, mode);
1370 int err = build_open_flags(&how, &op);
1371 if (err)
1372 return ERR_PTR(err);
1373 return do_filp_open(AT_FDCWD, name, &op);
1374 }
1375
1376 /**
1377 * filp_open - open file and return file pointer
1378 *
1379 * @filename: path to open
1380 * @flags: open flags as per the open(2) second argument
1381 * @mode: mode for the new file if O_CREAT is set, else ignored
1382 *
1383 * This is the helper to open a file from kernelspace if you really
1384 * have to. But in generally you should not do this, so please move
1385 * along, nothing to see here..
1386 */
filp_open(const char * filename,int flags,umode_t mode)1387 struct file *filp_open(const char *filename, int flags, umode_t mode)
1388 {
1389 struct filename *name = getname_kernel(filename);
1390 struct file *file = ERR_CAST(name);
1391
1392 if (!IS_ERR(name)) {
1393 file = file_open_name(name, flags, mode);
1394 putname(name);
1395 }
1396 return file;
1397 }
1398 EXPORT_SYMBOL(filp_open);
1399
file_open_root(const struct path * root,const char * filename,int flags,umode_t mode)1400 struct file *file_open_root(const struct path *root,
1401 const char *filename, int flags, umode_t mode)
1402 {
1403 struct open_flags op;
1404 struct open_how how = build_open_how(flags, mode);
1405 int err = build_open_flags(&how, &op);
1406 if (err)
1407 return ERR_PTR(err);
1408 return do_file_open_root(root, filename, &op);
1409 }
1410 EXPORT_SYMBOL(file_open_root);
1411
do_sys_openat2(int dfd,const char __user * filename,struct open_how * how)1412 static long do_sys_openat2(int dfd, const char __user *filename,
1413 struct open_how *how)
1414 {
1415 struct open_flags op;
1416 int fd = build_open_flags(how, &op);
1417 struct filename *tmp;
1418
1419 if (fd)
1420 return fd;
1421
1422 tmp = getname(filename);
1423 if (IS_ERR(tmp))
1424 return PTR_ERR(tmp);
1425
1426 fd = get_unused_fd_flags(how->flags);
1427 if (fd >= 0) {
1428 struct file *f = do_filp_open(dfd, tmp, &op);
1429 if (IS_ERR(f)) {
1430 put_unused_fd(fd);
1431 fd = PTR_ERR(f);
1432 } else {
1433 fd_install(fd, f);
1434 }
1435 }
1436 putname(tmp);
1437 return fd;
1438 }
1439
do_sys_open(int dfd,const char __user * filename,int flags,umode_t mode)1440 long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
1441 {
1442 struct open_how how = build_open_how(flags, mode);
1443 return do_sys_openat2(dfd, filename, &how);
1444 }
1445
1446
SYSCALL_DEFINE3(open,const char __user *,filename,int,flags,umode_t,mode)1447 SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1448 {
1449 if (force_o_largefile())
1450 flags |= O_LARGEFILE;
1451 return do_sys_open(AT_FDCWD, filename, flags, mode);
1452 }
1453
SYSCALL_DEFINE4(openat,int,dfd,const char __user *,filename,int,flags,umode_t,mode)1454 SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags,
1455 umode_t, mode)
1456 {
1457 if (force_o_largefile())
1458 flags |= O_LARGEFILE;
1459 return do_sys_open(dfd, filename, flags, mode);
1460 }
1461
SYSCALL_DEFINE4(openat2,int,dfd,const char __user *,filename,struct open_how __user *,how,size_t,usize)1462 SYSCALL_DEFINE4(openat2, int, dfd, const char __user *, filename,
1463 struct open_how __user *, how, size_t, usize)
1464 {
1465 int err;
1466 struct open_how tmp;
1467
1468 BUILD_BUG_ON(sizeof(struct open_how) < OPEN_HOW_SIZE_VER0);
1469 BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_LATEST);
1470
1471 if (unlikely(usize < OPEN_HOW_SIZE_VER0))
1472 return -EINVAL;
1473 if (unlikely(usize > PAGE_SIZE))
1474 return -E2BIG;
1475
1476 err = copy_struct_from_user(&tmp, sizeof(tmp), how, usize);
1477 if (err)
1478 return err;
1479
1480 audit_openat2_how(&tmp);
1481
1482 /* O_LARGEFILE is only allowed for non-O_PATH. */
1483 if (!(tmp.flags & O_PATH) && force_o_largefile())
1484 tmp.flags |= O_LARGEFILE;
1485
1486 return do_sys_openat2(dfd, filename, &tmp);
1487 }
1488
1489 #ifdef CONFIG_COMPAT
1490 /*
1491 * Exactly like sys_open(), except that it doesn't set the
1492 * O_LARGEFILE flag.
1493 */
COMPAT_SYSCALL_DEFINE3(open,const char __user *,filename,int,flags,umode_t,mode)1494 COMPAT_SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode)
1495 {
1496 return do_sys_open(AT_FDCWD, filename, flags, mode);
1497 }
1498
1499 /*
1500 * Exactly like sys_openat(), except that it doesn't set the
1501 * O_LARGEFILE flag.
1502 */
COMPAT_SYSCALL_DEFINE4(openat,int,dfd,const char __user *,filename,int,flags,umode_t,mode)1503 COMPAT_SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, umode_t, mode)
1504 {
1505 return do_sys_open(dfd, filename, flags, mode);
1506 }
1507 #endif
1508
1509 #ifndef __alpha__
1510
1511 /*
1512 * For backward compatibility? Maybe this should be moved
1513 * into arch/i386 instead?
1514 */
SYSCALL_DEFINE2(creat,const char __user *,pathname,umode_t,mode)1515 SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode)
1516 {
1517 int flags = O_CREAT | O_WRONLY | O_TRUNC;
1518
1519 if (force_o_largefile())
1520 flags |= O_LARGEFILE;
1521 return do_sys_open(AT_FDCWD, pathname, flags, mode);
1522 }
1523 #endif
1524
1525 /*
1526 * "id" is the POSIX thread ID. We use the
1527 * files pointer for this..
1528 */
filp_flush(struct file * filp,fl_owner_t id)1529 static int filp_flush(struct file *filp, fl_owner_t id)
1530 {
1531 int retval = 0;
1532
1533 if (CHECK_DATA_CORRUPTION(file_count(filp) == 0, filp,
1534 "VFS: Close: file count is 0 (f_op=%ps)",
1535 filp->f_op)) {
1536 return 0;
1537 }
1538
1539 if (filp->f_op->flush)
1540 retval = filp->f_op->flush(filp, id);
1541
1542 if (likely(!(filp->f_mode & FMODE_PATH))) {
1543 dnotify_flush(filp, id);
1544 locks_remove_posix(filp, id);
1545 }
1546 return retval;
1547 }
1548
filp_close(struct file * filp,fl_owner_t id)1549 int filp_close(struct file *filp, fl_owner_t id)
1550 {
1551 int retval;
1552
1553 retval = filp_flush(filp, id);
1554 fput(filp);
1555
1556 return retval;
1557 }
1558 EXPORT_SYMBOL(filp_close);
1559
1560 /*
1561 * Careful here! We test whether the file pointer is NULL before
1562 * releasing the fd. This ensures that one clone task can't release
1563 * an fd while another clone is opening it.
1564 */
SYSCALL_DEFINE1(close,unsigned int,fd)1565 SYSCALL_DEFINE1(close, unsigned int, fd)
1566 {
1567 int retval;
1568 struct file *file;
1569
1570 file = file_close_fd(fd);
1571 if (!file)
1572 return -EBADF;
1573
1574 retval = filp_flush(file, current->files);
1575
1576 /*
1577 * We're returning to user space. Don't bother
1578 * with any delayed fput() cases.
1579 */
1580 __fput_sync(file);
1581
1582 /* can't restart close syscall because file table entry was cleared */
1583 if (unlikely(retval == -ERESTARTSYS ||
1584 retval == -ERESTARTNOINTR ||
1585 retval == -ERESTARTNOHAND ||
1586 retval == -ERESTART_RESTARTBLOCK))
1587 retval = -EINTR;
1588
1589 return retval;
1590 }
1591
1592 /*
1593 * This routine simulates a hangup on the tty, to arrange that users
1594 * are given clean terminals at login time.
1595 */
SYSCALL_DEFINE0(vhangup)1596 SYSCALL_DEFINE0(vhangup)
1597 {
1598 if (capable(CAP_SYS_TTY_CONFIG)) {
1599 tty_vhangup_self();
1600 return 0;
1601 }
1602 return -EPERM;
1603 }
1604
1605 /*
1606 * Called when an inode is about to be open.
1607 * We use this to disallow opening large files on 32bit systems if
1608 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1609 * on this flag in sys_open.
1610 */
generic_file_open(struct inode * inode,struct file * filp)1611 int generic_file_open(struct inode * inode, struct file * filp)
1612 {
1613 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1614 return -EOVERFLOW;
1615 return 0;
1616 }
1617
1618 EXPORT_SYMBOL(generic_file_open);
1619
1620 /*
1621 * This is used by subsystems that don't want seekable
1622 * file descriptors. The function is not supposed to ever fail, the only
1623 * reason it returns an 'int' and not 'void' is so that it can be plugged
1624 * directly into file_operations structure.
1625 */
nonseekable_open(struct inode * inode,struct file * filp)1626 int nonseekable_open(struct inode *inode, struct file *filp)
1627 {
1628 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1629 return 0;
1630 }
1631
1632 EXPORT_SYMBOL(nonseekable_open);
1633
1634 /*
1635 * stream_open is used by subsystems that want stream-like file descriptors.
1636 * Such file descriptors are not seekable and don't have notion of position
1637 * (file.f_pos is always 0 and ppos passed to .read()/.write() is always NULL).
1638 * Contrary to file descriptors of other regular files, .read() and .write()
1639 * can run simultaneously.
1640 *
1641 * stream_open never fails and is marked to return int so that it could be
1642 * directly used as file_operations.open .
1643 */
stream_open(struct inode * inode,struct file * filp)1644 int stream_open(struct inode *inode, struct file *filp)
1645 {
1646 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE | FMODE_ATOMIC_POS);
1647 filp->f_mode |= FMODE_STREAM;
1648 return 0;
1649 }
1650
1651 EXPORT_SYMBOL(stream_open);
1652