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