]>
Commit | Line | Data |
---|---|---|
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 | ||
34 | #include "internal.h" | |
35 | ||
36 | int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, | |
37 | struct file *filp) | |
38 | { | |
39 | int ret; | |
40 | struct iattr newattrs; | |
41 | ||
42 | /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */ | |
43 | if (length < 0) | |
44 | return -EINVAL; | |
45 | ||
46 | newattrs.ia_size = length; | |
47 | newattrs.ia_valid = ATTR_SIZE | time_attrs; | |
48 | if (filp) { | |
49 | newattrs.ia_file = filp; | |
50 | newattrs.ia_valid |= ATTR_FILE; | |
51 | } | |
52 | ||
53 | /* Remove suid/sgid on truncate too */ | |
54 | ret = should_remove_suid(dentry); | |
55 | if (ret) | |
56 | newattrs.ia_valid |= ret | ATTR_FORCE; | |
57 | ||
58 | mutex_lock(&dentry->d_inode->i_mutex); | |
59 | ret = notify_change(dentry, &newattrs); | |
60 | mutex_unlock(&dentry->d_inode->i_mutex); | |
61 | return ret; | |
62 | } | |
63 | ||
64 | static long do_sys_truncate(const char __user *pathname, loff_t length) | |
65 | { | |
66 | struct path path; | |
67 | struct inode *inode; | |
68 | int error; | |
69 | ||
70 | error = -EINVAL; | |
71 | if (length < 0) /* sorry, but loff_t says... */ | |
72 | goto out; | |
73 | ||
74 | error = user_path(pathname, &path); | |
75 | if (error) | |
76 | goto out; | |
77 | inode = path.dentry->d_inode; | |
78 | ||
79 | /* For directories it's -EISDIR, for other non-regulars - -EINVAL */ | |
80 | error = -EISDIR; | |
81 | if (S_ISDIR(inode->i_mode)) | |
82 | goto dput_and_out; | |
83 | ||
84 | error = -EINVAL; | |
85 | if (!S_ISREG(inode->i_mode)) | |
86 | goto dput_and_out; | |
87 | ||
88 | error = mnt_want_write(path.mnt); | |
89 | if (error) | |
90 | goto dput_and_out; | |
91 | ||
92 | error = inode_permission(inode, MAY_WRITE); | |
93 | if (error) | |
94 | goto mnt_drop_write_and_out; | |
95 | ||
96 | error = -EPERM; | |
97 | if (IS_APPEND(inode)) | |
98 | goto mnt_drop_write_and_out; | |
99 | ||
100 | error = get_write_access(inode); | |
101 | if (error) | |
102 | goto mnt_drop_write_and_out; | |
103 | ||
104 | /* | |
105 | * Make sure that there are no leases. get_write_access() protects | |
106 | * against the truncate racing with a lease-granting setlease(). | |
107 | */ | |
108 | error = break_lease(inode, O_WRONLY); | |
109 | if (error) | |
110 | goto put_write_and_out; | |
111 | ||
112 | error = locks_verify_truncate(inode, NULL, length); | |
113 | if (!error) | |
114 | error = security_path_truncate(&path); | |
115 | if (!error) | |
116 | error = do_truncate(path.dentry, length, 0, NULL); | |
117 | ||
118 | put_write_and_out: | |
119 | put_write_access(inode); | |
120 | mnt_drop_write_and_out: | |
121 | mnt_drop_write(path.mnt); | |
122 | dput_and_out: | |
123 | path_put(&path); | |
124 | out: | |
125 | return error; | |
126 | } | |
127 | ||
128 | SYSCALL_DEFINE2(truncate, const char __user *, path, long, length) | |
129 | { | |
130 | return do_sys_truncate(path, length); | |
131 | } | |
132 | ||
133 | static long do_sys_ftruncate(unsigned int fd, loff_t length, int small) | |
134 | { | |
135 | struct inode * inode; | |
136 | struct dentry *dentry; | |
137 | struct file * file; | |
138 | int error; | |
139 | ||
140 | error = -EINVAL; | |
141 | if (length < 0) | |
142 | goto out; | |
143 | error = -EBADF; | |
144 | file = fget(fd); | |
145 | if (!file) | |
146 | goto out; | |
147 | ||
148 | /* explicitly opened as large or we are on 64-bit box */ | |
149 | if (file->f_flags & O_LARGEFILE) | |
150 | small = 0; | |
151 | ||
152 | dentry = file->f_path.dentry; | |
153 | inode = dentry->d_inode; | |
154 | error = -EINVAL; | |
155 | if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE)) | |
156 | goto out_putf; | |
157 | ||
158 | error = -EINVAL; | |
159 | /* Cannot ftruncate over 2^31 bytes without large file support */ | |
160 | if (small && length > MAX_NON_LFS) | |
161 | goto out_putf; | |
162 | ||
163 | error = -EPERM; | |
164 | if (IS_APPEND(inode)) | |
165 | goto out_putf; | |
166 | ||
167 | error = locks_verify_truncate(inode, file, length); | |
168 | if (!error) | |
169 | error = security_path_truncate(&file->f_path); | |
170 | if (!error) | |
171 | error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file); | |
172 | out_putf: | |
173 | fput(file); | |
174 | out: | |
175 | return error; | |
176 | } | |
177 | ||
178 | SYSCALL_DEFINE2(ftruncate, unsigned int, fd, unsigned long, length) | |
179 | { | |
180 | long ret = do_sys_ftruncate(fd, length, 1); | |
181 | /* avoid REGPARM breakage on x86: */ | |
182 | asmlinkage_protect(2, ret, fd, length); | |
183 | return ret; | |
184 | } | |
185 | ||
186 | /* LFS versions of truncate are only needed on 32 bit machines */ | |
187 | #if BITS_PER_LONG == 32 | |
188 | SYSCALL_DEFINE(truncate64)(const char __user * path, loff_t length) | |
189 | { | |
190 | return do_sys_truncate(path, length); | |
191 | } | |
192 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS | |
193 | asmlinkage long SyS_truncate64(long path, loff_t length) | |
194 | { | |
195 | return SYSC_truncate64((const char __user *) path, length); | |
196 | } | |
197 | SYSCALL_ALIAS(sys_truncate64, SyS_truncate64); | |
198 | #endif | |
199 | ||
200 | SYSCALL_DEFINE(ftruncate64)(unsigned int fd, loff_t length) | |
201 | { | |
202 | long ret = do_sys_ftruncate(fd, length, 0); | |
203 | /* avoid REGPARM breakage on x86: */ | |
204 | asmlinkage_protect(2, ret, fd, length); | |
205 | return ret; | |
206 | } | |
207 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS | |
208 | asmlinkage long SyS_ftruncate64(long fd, loff_t length) | |
209 | { | |
210 | return SYSC_ftruncate64((unsigned int) fd, length); | |
211 | } | |
212 | SYSCALL_ALIAS(sys_ftruncate64, SyS_ftruncate64); | |
213 | #endif | |
214 | #endif /* BITS_PER_LONG == 32 */ | |
215 | ||
216 | ||
217 | int do_fallocate(struct file *file, int mode, loff_t offset, loff_t len) | |
218 | { | |
219 | struct inode *inode = file->f_path.dentry->d_inode; | |
220 | long ret; | |
221 | ||
222 | if (offset < 0 || len <= 0) | |
223 | return -EINVAL; | |
224 | ||
225 | /* Return error if mode is not supported */ | |
226 | if (mode && !(mode & FALLOC_FL_KEEP_SIZE)) | |
227 | return -EOPNOTSUPP; | |
228 | ||
229 | if (!(file->f_mode & FMODE_WRITE)) | |
230 | return -EBADF; | |
231 | /* | |
232 | * Revalidate the write permissions, in case security policy has | |
233 | * changed since the files were opened. | |
234 | */ | |
235 | ret = security_file_permission(file, MAY_WRITE); | |
236 | if (ret) | |
237 | return ret; | |
238 | ||
239 | if (S_ISFIFO(inode->i_mode)) | |
240 | return -ESPIPE; | |
241 | ||
242 | /* | |
243 | * Let individual file system decide if it supports preallocation | |
244 | * for directories or not. | |
245 | */ | |
246 | if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) | |
247 | return -ENODEV; | |
248 | ||
249 | /* Check for wrap through zero too */ | |
250 | if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0)) | |
251 | return -EFBIG; | |
252 | ||
253 | if (!inode->i_op->fallocate) | |
254 | return -EOPNOTSUPP; | |
255 | ||
256 | return inode->i_op->fallocate(inode, mode, offset, len); | |
257 | } | |
258 | ||
259 | SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len) | |
260 | { | |
261 | struct file *file; | |
262 | int error = -EBADF; | |
263 | ||
264 | file = fget(fd); | |
265 | if (file) { | |
266 | error = do_fallocate(file, mode, offset, len); | |
267 | fput(file); | |
268 | } | |
269 | ||
270 | return error; | |
271 | } | |
272 | ||
273 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS | |
274 | asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len) | |
275 | { | |
276 | return SYSC_fallocate((int)fd, (int)mode, offset, len); | |
277 | } | |
278 | SYSCALL_ALIAS(sys_fallocate, SyS_fallocate); | |
279 | #endif | |
280 | ||
281 | /* | |
282 | * access() needs to use the real uid/gid, not the effective uid/gid. | |
283 | * We do this by temporarily clearing all FS-related capabilities and | |
284 | * switching the fsuid/fsgid around to the real ones. | |
285 | */ | |
286 | SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode) | |
287 | { | |
288 | const struct cred *old_cred; | |
289 | struct cred *override_cred; | |
290 | struct path path; | |
291 | struct inode *inode; | |
292 | int res; | |
293 | ||
294 | if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ | |
295 | return -EINVAL; | |
296 | ||
297 | override_cred = prepare_creds(); | |
298 | if (!override_cred) | |
299 | return -ENOMEM; | |
300 | ||
301 | override_cred->fsuid = override_cred->uid; | |
302 | override_cred->fsgid = override_cred->gid; | |
303 | ||
304 | if (!issecure(SECURE_NO_SETUID_FIXUP)) { | |
305 | /* Clear the capabilities if we switch to a non-root user */ | |
306 | if (override_cred->uid) | |
307 | cap_clear(override_cred->cap_effective); | |
308 | else | |
309 | override_cred->cap_effective = | |
310 | override_cred->cap_permitted; | |
311 | } | |
312 | ||
313 | old_cred = override_creds(override_cred); | |
314 | ||
315 | res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path); | |
316 | if (res) | |
317 | goto out; | |
318 | ||
319 | inode = path.dentry->d_inode; | |
320 | ||
321 | if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) { | |
322 | /* | |
323 | * MAY_EXEC on regular files is denied if the fs is mounted | |
324 | * with the "noexec" flag. | |
325 | */ | |
326 | res = -EACCES; | |
327 | if (path.mnt->mnt_flags & MNT_NOEXEC) | |
328 | goto out_path_release; | |
329 | } | |
330 | ||
331 | res = inode_permission(inode, mode | MAY_ACCESS); | |
332 | /* SuS v2 requires we report a read only fs too */ | |
333 | if (res || !(mode & S_IWOTH) || special_file(inode->i_mode)) | |
334 | goto out_path_release; | |
335 | /* | |
336 | * This is a rare case where using __mnt_is_readonly() | |
337 | * is OK without a mnt_want/drop_write() pair. Since | |
338 | * no actual write to the fs is performed here, we do | |
339 | * not need to telegraph to that to anyone. | |
340 | * | |
341 | * By doing this, we accept that this access is | |
342 | * inherently racy and know that the fs may change | |
343 | * state before we even see this result. | |
344 | */ | |
345 | if (__mnt_is_readonly(path.mnt)) | |
346 | res = -EROFS; | |
347 | ||
348 | out_path_release: | |
349 | path_put(&path); | |
350 | out: | |
351 | revert_creds(old_cred); | |
352 | put_cred(override_cred); | |
353 | return res; | |
354 | } | |
355 | ||
356 | SYSCALL_DEFINE2(access, const char __user *, filename, int, mode) | |
357 | { | |
358 | return sys_faccessat(AT_FDCWD, filename, mode); | |
359 | } | |
360 | ||
361 | SYSCALL_DEFINE1(chdir, const char __user *, filename) | |
362 | { | |
363 | struct path path; | |
364 | int error; | |
365 | ||
366 | error = user_path_dir(filename, &path); | |
367 | if (error) | |
368 | goto out; | |
369 | ||
370 | error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR); | |
371 | if (error) | |
372 | goto dput_and_out; | |
373 | ||
374 | set_fs_pwd(current->fs, &path); | |
375 | ||
376 | dput_and_out: | |
377 | path_put(&path); | |
378 | out: | |
379 | return error; | |
380 | } | |
381 | ||
382 | SYSCALL_DEFINE1(fchdir, unsigned int, fd) | |
383 | { | |
384 | struct file *file; | |
385 | struct inode *inode; | |
386 | int error; | |
387 | ||
388 | error = -EBADF; | |
389 | file = fget(fd); | |
390 | if (!file) | |
391 | goto out; | |
392 | ||
393 | inode = file->f_path.dentry->d_inode; | |
394 | ||
395 | error = -ENOTDIR; | |
396 | if (!S_ISDIR(inode->i_mode)) | |
397 | goto out_putf; | |
398 | ||
399 | error = inode_permission(inode, MAY_EXEC | MAY_CHDIR); | |
400 | if (!error) | |
401 | set_fs_pwd(current->fs, &file->f_path); | |
402 | out_putf: | |
403 | fput(file); | |
404 | out: | |
405 | return error; | |
406 | } | |
407 | ||
408 | SYSCALL_DEFINE1(chroot, const char __user *, filename) | |
409 | { | |
410 | struct path path; | |
411 | int error; | |
412 | ||
413 | error = user_path_dir(filename, &path); | |
414 | if (error) | |
415 | goto out; | |
416 | ||
417 | error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR); | |
418 | if (error) | |
419 | goto dput_and_out; | |
420 | ||
421 | error = -EPERM; | |
422 | if (!capable(CAP_SYS_CHROOT)) | |
423 | goto dput_and_out; | |
424 | error = security_path_chroot(&path); | |
425 | if (error) | |
426 | goto dput_and_out; | |
427 | ||
428 | set_fs_root(current->fs, &path); | |
429 | error = 0; | |
430 | dput_and_out: | |
431 | path_put(&path); | |
432 | out: | |
433 | return error; | |
434 | } | |
435 | ||
436 | SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode) | |
437 | { | |
438 | struct inode * inode; | |
439 | struct dentry * dentry; | |
440 | struct file * file; | |
441 | int err = -EBADF; | |
442 | struct iattr newattrs; | |
443 | ||
444 | file = fget(fd); | |
445 | if (!file) | |
446 | goto out; | |
447 | ||
448 | dentry = file->f_path.dentry; | |
449 | inode = dentry->d_inode; | |
450 | ||
451 | audit_inode(NULL, dentry); | |
452 | ||
453 | err = mnt_want_write_file(file); | |
454 | if (err) | |
455 | goto out_putf; | |
456 | mutex_lock(&inode->i_mutex); | |
457 | err = security_path_chmod(dentry, file->f_vfsmnt, mode); | |
458 | if (err) | |
459 | goto out_unlock; | |
460 | if (mode == (mode_t) -1) | |
461 | mode = inode->i_mode; | |
462 | newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); | |
463 | newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; | |
464 | err = notify_change(dentry, &newattrs); | |
465 | out_unlock: | |
466 | mutex_unlock(&inode->i_mutex); | |
467 | mnt_drop_write(file->f_path.mnt); | |
468 | out_putf: | |
469 | fput(file); | |
470 | out: | |
471 | return err; | |
472 | } | |
473 | ||
474 | SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode) | |
475 | { | |
476 | struct path path; | |
477 | struct inode *inode; | |
478 | int error; | |
479 | struct iattr newattrs; | |
480 | ||
481 | error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path); | |
482 | if (error) | |
483 | goto out; | |
484 | inode = path.dentry->d_inode; | |
485 | ||
486 | error = mnt_want_write(path.mnt); | |
487 | if (error) | |
488 | goto dput_and_out; | |
489 | mutex_lock(&inode->i_mutex); | |
490 | error = security_path_chmod(path.dentry, path.mnt, mode); | |
491 | if (error) | |
492 | goto out_unlock; | |
493 | if (mode == (mode_t) -1) | |
494 | mode = inode->i_mode; | |
495 | newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); | |
496 | newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; | |
497 | error = notify_change(path.dentry, &newattrs); | |
498 | out_unlock: | |
499 | mutex_unlock(&inode->i_mutex); | |
500 | mnt_drop_write(path.mnt); | |
501 | dput_and_out: | |
502 | path_put(&path); | |
503 | out: | |
504 | return error; | |
505 | } | |
506 | ||
507 | SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_t, mode) | |
508 | { | |
509 | return sys_fchmodat(AT_FDCWD, filename, mode); | |
510 | } | |
511 | ||
512 | static int chown_common(struct path *path, uid_t user, gid_t group) | |
513 | { | |
514 | struct inode *inode = path->dentry->d_inode; | |
515 | int error; | |
516 | struct iattr newattrs; | |
517 | ||
518 | newattrs.ia_valid = ATTR_CTIME; | |
519 | if (user != (uid_t) -1) { | |
520 | newattrs.ia_valid |= ATTR_UID; | |
521 | newattrs.ia_uid = user; | |
522 | } | |
523 | if (group != (gid_t) -1) { | |
524 | newattrs.ia_valid |= ATTR_GID; | |
525 | newattrs.ia_gid = group; | |
526 | } | |
527 | if (!S_ISDIR(inode->i_mode)) | |
528 | newattrs.ia_valid |= | |
529 | ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV; | |
530 | mutex_lock(&inode->i_mutex); | |
531 | error = security_path_chown(path, user, group); | |
532 | if (!error) | |
533 | error = notify_change(path->dentry, &newattrs); | |
534 | mutex_unlock(&inode->i_mutex); | |
535 | ||
536 | return error; | |
537 | } | |
538 | ||
539 | SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group) | |
540 | { | |
541 | struct path path; | |
542 | int error; | |
543 | ||
544 | error = user_path(filename, &path); | |
545 | if (error) | |
546 | goto out; | |
547 | error = mnt_want_write(path.mnt); | |
548 | if (error) | |
549 | goto out_release; | |
550 | error = chown_common(&path, user, group); | |
551 | mnt_drop_write(path.mnt); | |
552 | out_release: | |
553 | path_put(&path); | |
554 | out: | |
555 | return error; | |
556 | } | |
557 | ||
558 | SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user, | |
559 | gid_t, group, int, flag) | |
560 | { | |
561 | struct path path; | |
562 | int error = -EINVAL; | |
563 | int follow; | |
564 | ||
565 | if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0) | |
566 | goto out; | |
567 | ||
568 | follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; | |
569 | error = user_path_at(dfd, filename, follow, &path); | |
570 | if (error) | |
571 | goto out; | |
572 | error = mnt_want_write(path.mnt); | |
573 | if (error) | |
574 | goto out_release; | |
575 | error = chown_common(&path, user, group); | |
576 | mnt_drop_write(path.mnt); | |
577 | out_release: | |
578 | path_put(&path); | |
579 | out: | |
580 | return error; | |
581 | } | |
582 | ||
583 | SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group) | |
584 | { | |
585 | struct path path; | |
586 | int error; | |
587 | ||
588 | error = user_lpath(filename, &path); | |
589 | if (error) | |
590 | goto out; | |
591 | error = mnt_want_write(path.mnt); | |
592 | if (error) | |
593 | goto out_release; | |
594 | error = chown_common(&path, user, group); | |
595 | mnt_drop_write(path.mnt); | |
596 | out_release: | |
597 | path_put(&path); | |
598 | out: | |
599 | return error; | |
600 | } | |
601 | ||
602 | SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) | |
603 | { | |
604 | struct file * file; | |
605 | int error = -EBADF; | |
606 | struct dentry * dentry; | |
607 | ||
608 | file = fget(fd); | |
609 | if (!file) | |
610 | goto out; | |
611 | ||
612 | error = mnt_want_write_file(file); | |
613 | if (error) | |
614 | goto out_fput; | |
615 | dentry = file->f_path.dentry; | |
616 | audit_inode(NULL, dentry); | |
617 | error = chown_common(&file->f_path, user, group); | |
618 | mnt_drop_write(file->f_path.mnt); | |
619 | out_fput: | |
620 | fput(file); | |
621 | out: | |
622 | return error; | |
623 | } | |
624 | ||
625 | /* | |
626 | * You have to be very careful that these write | |
627 | * counts get cleaned up in error cases and | |
628 | * upon __fput(). This should probably never | |
629 | * be called outside of __dentry_open(). | |
630 | */ | |
631 | static inline int __get_file_write_access(struct inode *inode, | |
632 | struct vfsmount *mnt) | |
633 | { | |
634 | int error; | |
635 | error = get_write_access(inode); | |
636 | if (error) | |
637 | return error; | |
638 | /* | |
639 | * Do not take mount writer counts on | |
640 | * special files since no writes to | |
641 | * the mount itself will occur. | |
642 | */ | |
643 | if (!special_file(inode->i_mode)) { | |
644 | /* | |
645 | * Balanced in __fput() | |
646 | */ | |
647 | error = mnt_want_write(mnt); | |
648 | if (error) | |
649 | put_write_access(inode); | |
650 | } | |
651 | return error; | |
652 | } | |
653 | ||
654 | static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt, | |
655 | struct file *f, | |
656 | int (*open)(struct inode *, struct file *), | |
657 | const struct cred *cred) | |
658 | { | |
659 | struct inode *inode; | |
660 | int error; | |
661 | ||
662 | f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK | | |
663 | FMODE_PREAD | FMODE_PWRITE; | |
664 | inode = dentry->d_inode; | |
665 | if (f->f_mode & FMODE_WRITE) { | |
666 | error = __get_file_write_access(inode, mnt); | |
667 | if (error) | |
668 | goto cleanup_file; | |
669 | if (!special_file(inode->i_mode)) | |
670 | file_take_write(f); | |
671 | } | |
672 | ||
673 | f->f_mapping = inode->i_mapping; | |
674 | f->f_path.dentry = dentry; | |
675 | f->f_path.mnt = mnt; | |
676 | f->f_pos = 0; | |
677 | f->f_op = fops_get(inode->i_fop); | |
678 | file_sb_list_add(f, inode->i_sb); | |
679 | ||
680 | error = security_dentry_open(f, cred); | |
681 | if (error) | |
682 | goto cleanup_all; | |
683 | ||
684 | if (!open && f->f_op) | |
685 | open = f->f_op->open; | |
686 | if (open) { | |
687 | error = open(inode, f); | |
688 | if (error) | |
689 | goto cleanup_all; | |
690 | } | |
691 | ima_counts_get(f); | |
692 | ||
693 | f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); | |
694 | ||
695 | file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); | |
696 | ||
697 | /* NB: we're sure to have correct a_ops only after f_op->open */ | |
698 | if (f->f_flags & O_DIRECT) { | |
699 | if (!f->f_mapping->a_ops || | |
700 | ((!f->f_mapping->a_ops->direct_IO) && | |
701 | (!f->f_mapping->a_ops->get_xip_mem))) { | |
702 | fput(f); | |
703 | f = ERR_PTR(-EINVAL); | |
704 | } | |
705 | } | |
706 | ||
707 | return f; | |
708 | ||
709 | cleanup_all: | |
710 | fops_put(f->f_op); | |
711 | if (f->f_mode & FMODE_WRITE) { | |
712 | put_write_access(inode); | |
713 | if (!special_file(inode->i_mode)) { | |
714 | /* | |
715 | * We don't consider this a real | |
716 | * mnt_want/drop_write() pair | |
717 | * because it all happenend right | |
718 | * here, so just reset the state. | |
719 | */ | |
720 | file_reset_write(f); | |
721 | mnt_drop_write(mnt); | |
722 | } | |
723 | } | |
724 | file_sb_list_del(f); | |
725 | f->f_path.dentry = NULL; | |
726 | f->f_path.mnt = NULL; | |
727 | cleanup_file: | |
728 | put_filp(f); | |
729 | dput(dentry); | |
730 | mntput(mnt); | |
731 | return ERR_PTR(error); | |
732 | } | |
733 | ||
734 | /** | |
735 | * lookup_instantiate_filp - instantiates the open intent filp | |
736 | * @nd: pointer to nameidata | |
737 | * @dentry: pointer to dentry | |
738 | * @open: open callback | |
739 | * | |
740 | * Helper for filesystems that want to use lookup open intents and pass back | |
741 | * a fully instantiated struct file to the caller. | |
742 | * This function is meant to be called from within a filesystem's | |
743 | * lookup method. | |
744 | * Beware of calling it for non-regular files! Those ->open methods might block | |
745 | * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo, | |
746 | * leading to a deadlock, as nobody can open that fifo anymore, because | |
747 | * another process to open fifo will block on locked parent when doing lookup). | |
748 | * Note that in case of error, nd->intent.open.file is destroyed, but the | |
749 | * path information remains valid. | |
750 | * If the open callback is set to NULL, then the standard f_op->open() | |
751 | * filesystem callback is substituted. | |
752 | */ | |
753 | struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry, | |
754 | int (*open)(struct inode *, struct file *)) | |
755 | { | |
756 | const struct cred *cred = current_cred(); | |
757 | ||
758 | if (IS_ERR(nd->intent.open.file)) | |
759 | goto out; | |
760 | if (IS_ERR(dentry)) | |
761 | goto out_err; | |
762 | nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt), | |
763 | nd->intent.open.file, | |
764 | open, cred); | |
765 | out: | |
766 | return nd->intent.open.file; | |
767 | out_err: | |
768 | release_open_intent(nd); | |
769 | nd->intent.open.file = (struct file *)dentry; | |
770 | goto out; | |
771 | } | |
772 | EXPORT_SYMBOL_GPL(lookup_instantiate_filp); | |
773 | ||
774 | /** | |
775 | * nameidata_to_filp - convert a nameidata to an open filp. | |
776 | * @nd: pointer to nameidata | |
777 | * @flags: open flags | |
778 | * | |
779 | * Note that this function destroys the original nameidata | |
780 | */ | |
781 | struct file *nameidata_to_filp(struct nameidata *nd) | |
782 | { | |
783 | const struct cred *cred = current_cred(); | |
784 | struct file *filp; | |
785 | ||
786 | /* Pick up the filp from the open intent */ | |
787 | filp = nd->intent.open.file; | |
788 | /* Has the filesystem initialised the file for us? */ | |
789 | if (filp->f_path.dentry == NULL) { | |
790 | path_get(&nd->path); | |
791 | filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp, | |
792 | NULL, cred); | |
793 | } | |
794 | return filp; | |
795 | } | |
796 | ||
797 | /* | |
798 | * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an | |
799 | * error. | |
800 | */ | |
801 | struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags, | |
802 | const struct cred *cred) | |
803 | { | |
804 | int error; | |
805 | struct file *f; | |
806 | ||
807 | validate_creds(cred); | |
808 | ||
809 | /* | |
810 | * We must always pass in a valid mount pointer. Historically | |
811 | * callers got away with not passing it, but we must enforce this at | |
812 | * the earliest possible point now to avoid strange problems deep in the | |
813 | * filesystem stack. | |
814 | */ | |
815 | if (!mnt) { | |
816 | printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__); | |
817 | dump_stack(); | |
818 | return ERR_PTR(-EINVAL); | |
819 | } | |
820 | ||
821 | error = -ENFILE; | |
822 | f = get_empty_filp(); | |
823 | if (f == NULL) { | |
824 | dput(dentry); | |
825 | mntput(mnt); | |
826 | return ERR_PTR(error); | |
827 | } | |
828 | ||
829 | f->f_flags = flags; | |
830 | return __dentry_open(dentry, mnt, f, NULL, cred); | |
831 | } | |
832 | EXPORT_SYMBOL(dentry_open); | |
833 | ||
834 | static void __put_unused_fd(struct files_struct *files, unsigned int fd) | |
835 | { | |
836 | struct fdtable *fdt = files_fdtable(files); | |
837 | __FD_CLR(fd, fdt->open_fds); | |
838 | if (fd < files->next_fd) | |
839 | files->next_fd = fd; | |
840 | } | |
841 | ||
842 | void put_unused_fd(unsigned int fd) | |
843 | { | |
844 | struct files_struct *files = current->files; | |
845 | spin_lock(&files->file_lock); | |
846 | __put_unused_fd(files, fd); | |
847 | spin_unlock(&files->file_lock); | |
848 | } | |
849 | ||
850 | EXPORT_SYMBOL(put_unused_fd); | |
851 | ||
852 | /* | |
853 | * Install a file pointer in the fd array. | |
854 | * | |
855 | * The VFS is full of places where we drop the files lock between | |
856 | * setting the open_fds bitmap and installing the file in the file | |
857 | * array. At any such point, we are vulnerable to a dup2() race | |
858 | * installing a file in the array before us. We need to detect this and | |
859 | * fput() the struct file we are about to overwrite in this case. | |
860 | * | |
861 | * It should never happen - if we allow dup2() do it, _really_ bad things | |
862 | * will follow. | |
863 | */ | |
864 | ||
865 | void fd_install(unsigned int fd, struct file *file) | |
866 | { | |
867 | struct files_struct *files = current->files; | |
868 | struct fdtable *fdt; | |
869 | spin_lock(&files->file_lock); | |
870 | fdt = files_fdtable(files); | |
871 | BUG_ON(fdt->fd[fd] != NULL); | |
872 | rcu_assign_pointer(fdt->fd[fd], file); | |
873 | spin_unlock(&files->file_lock); | |
874 | } | |
875 | ||
876 | EXPORT_SYMBOL(fd_install); | |
877 | ||
878 | long do_sys_open(int dfd, const char __user *filename, int flags, int mode) | |
879 | { | |
880 | char *tmp = getname(filename); | |
881 | int fd = PTR_ERR(tmp); | |
882 | ||
883 | if (!IS_ERR(tmp)) { | |
884 | fd = get_unused_fd_flags(flags); | |
885 | if (fd >= 0) { | |
886 | struct file *f = do_filp_open(dfd, tmp, flags, mode, 0); | |
887 | if (IS_ERR(f)) { | |
888 | put_unused_fd(fd); | |
889 | fd = PTR_ERR(f); | |
890 | } else { | |
891 | fsnotify_open(f); | |
892 | fd_install(fd, f); | |
893 | } | |
894 | } | |
895 | putname(tmp); | |
896 | } | |
897 | return fd; | |
898 | } | |
899 | ||
900 | SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, mode) | |
901 | { | |
902 | long ret; | |
903 | ||
904 | if (force_o_largefile()) | |
905 | flags |= O_LARGEFILE; | |
906 | ||
907 | ret = do_sys_open(AT_FDCWD, filename, flags, mode); | |
908 | /* avoid REGPARM breakage on x86: */ | |
909 | asmlinkage_protect(3, ret, filename, flags, mode); | |
910 | return ret; | |
911 | } | |
912 | ||
913 | SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, | |
914 | int, mode) | |
915 | { | |
916 | long ret; | |
917 | ||
918 | if (force_o_largefile()) | |
919 | flags |= O_LARGEFILE; | |
920 | ||
921 | ret = do_sys_open(dfd, filename, flags, mode); | |
922 | /* avoid REGPARM breakage on x86: */ | |
923 | asmlinkage_protect(4, ret, dfd, filename, flags, mode); | |
924 | return ret; | |
925 | } | |
926 | ||
927 | #ifndef __alpha__ | |
928 | ||
929 | /* | |
930 | * For backward compatibility? Maybe this should be moved | |
931 | * into arch/i386 instead? | |
932 | */ | |
933 | SYSCALL_DEFINE2(creat, const char __user *, pathname, int, mode) | |
934 | { | |
935 | return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode); | |
936 | } | |
937 | ||
938 | #endif | |
939 | ||
940 | /* | |
941 | * "id" is the POSIX thread ID. We use the | |
942 | * files pointer for this.. | |
943 | */ | |
944 | int filp_close(struct file *filp, fl_owner_t id) | |
945 | { | |
946 | int retval = 0; | |
947 | ||
948 | if (!file_count(filp)) { | |
949 | printk(KERN_ERR "VFS: Close: file count is 0\n"); | |
950 | return 0; | |
951 | } | |
952 | ||
953 | if (filp->f_op && filp->f_op->flush) | |
954 | retval = filp->f_op->flush(filp, id); | |
955 | ||
956 | dnotify_flush(filp, id); | |
957 | locks_remove_posix(filp, id); | |
958 | fput(filp); | |
959 | return retval; | |
960 | } | |
961 | ||
962 | EXPORT_SYMBOL(filp_close); | |
963 | ||
964 | /* | |
965 | * Careful here! We test whether the file pointer is NULL before | |
966 | * releasing the fd. This ensures that one clone task can't release | |
967 | * an fd while another clone is opening it. | |
968 | */ | |
969 | SYSCALL_DEFINE1(close, unsigned int, fd) | |
970 | { | |
971 | struct file * filp; | |
972 | struct files_struct *files = current->files; | |
973 | struct fdtable *fdt; | |
974 | int retval; | |
975 | ||
976 | spin_lock(&files->file_lock); | |
977 | fdt = files_fdtable(files); | |
978 | if (fd >= fdt->max_fds) | |
979 | goto out_unlock; | |
980 | filp = fdt->fd[fd]; | |
981 | if (!filp) | |
982 | goto out_unlock; | |
983 | rcu_assign_pointer(fdt->fd[fd], NULL); | |
984 | FD_CLR(fd, fdt->close_on_exec); | |
985 | __put_unused_fd(files, fd); | |
986 | spin_unlock(&files->file_lock); | |
987 | retval = filp_close(filp, files); | |
988 | ||
989 | /* can't restart close syscall because file table entry was cleared */ | |
990 | if (unlikely(retval == -ERESTARTSYS || | |
991 | retval == -ERESTARTNOINTR || | |
992 | retval == -ERESTARTNOHAND || | |
993 | retval == -ERESTART_RESTARTBLOCK)) | |
994 | retval = -EINTR; | |
995 | ||
996 | return retval; | |
997 | ||
998 | out_unlock: | |
999 | spin_unlock(&files->file_lock); | |
1000 | return -EBADF; | |
1001 | } | |
1002 | EXPORT_SYMBOL(sys_close); | |
1003 | ||
1004 | /* | |
1005 | * This routine simulates a hangup on the tty, to arrange that users | |
1006 | * are given clean terminals at login time. | |
1007 | */ | |
1008 | SYSCALL_DEFINE0(vhangup) | |
1009 | { | |
1010 | if (capable(CAP_SYS_TTY_CONFIG)) { | |
1011 | tty_vhangup_self(); | |
1012 | return 0; | |
1013 | } | |
1014 | return -EPERM; | |
1015 | } | |
1016 | ||
1017 | /* | |
1018 | * Called when an inode is about to be open. | |
1019 | * We use this to disallow opening large files on 32bit systems if | |
1020 | * the caller didn't specify O_LARGEFILE. On 64bit systems we force | |
1021 | * on this flag in sys_open. | |
1022 | */ | |
1023 | int generic_file_open(struct inode * inode, struct file * filp) | |
1024 | { | |
1025 | if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS) | |
1026 | return -EOVERFLOW; | |
1027 | return 0; | |
1028 | } | |
1029 | ||
1030 | EXPORT_SYMBOL(generic_file_open); | |
1031 | ||
1032 | /* | |
1033 | * This is used by subsystems that don't want seekable | |
1034 | * file descriptors. The function is not supposed to ever fail, the only | |
1035 | * reason it returns an 'int' and not 'void' is so that it can be plugged | |
1036 | * directly into file_operations structure. | |
1037 | */ | |
1038 | int nonseekable_open(struct inode *inode, struct file *filp) | |
1039 | { | |
1040 | filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE); | |
1041 | return 0; | |
1042 | } | |
1043 | ||
1044 | EXPORT_SYMBOL(nonseekable_open); |