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