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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 | |
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 & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE)) |
227 | return -EOPNOTSUPP; |
228 | |
229 | /* Punch hole must have keep size set */ |
230 | if ((mode & FALLOC_FL_PUNCH_HOLE) && |
231 | !(mode & FALLOC_FL_KEEP_SIZE)) |
232 | return -EOPNOTSUPP; |
233 | |
234 | if (!(file->f_mode & FMODE_WRITE)) |
235 | return -EBADF; |
236 | |
237 | /* It's not possible punch hole on append only file */ |
238 | if (mode & FALLOC_FL_PUNCH_HOLE && IS_APPEND(inode)) |
239 | return -EPERM; |
240 | |
241 | if (IS_IMMUTABLE(inode)) |
242 | return -EPERM; |
243 | |
244 | /* |
245 | * Revalidate the write permissions, in case security policy has |
246 | * changed since the files were opened. |
247 | */ |
248 | ret = security_file_permission(file, MAY_WRITE); |
249 | if (ret) |
250 | return ret; |
251 | |
252 | if (S_ISFIFO(inode->i_mode)) |
253 | return -ESPIPE; |
254 | |
255 | /* |
256 | * Let individual file system decide if it supports preallocation |
257 | * for directories or not. |
258 | */ |
259 | if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) |
260 | return -ENODEV; |
261 | |
262 | /* Check for wrap through zero too */ |
263 | if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0)) |
264 | return -EFBIG; |
265 | |
266 | if (!file->f_op->fallocate) |
267 | return -EOPNOTSUPP; |
268 | |
269 | return file->f_op->fallocate(file, mode, offset, len); |
270 | } |
271 | |
272 | SYSCALL_DEFINE(fallocate)(int fd, int mode, loff_t offset, loff_t len) |
273 | { |
274 | struct file *file; |
275 | int error = -EBADF; |
276 | |
277 | file = fget(fd); |
278 | if (file) { |
279 | error = do_fallocate(file, mode, offset, len); |
280 | fput(file); |
281 | } |
282 | |
283 | return error; |
284 | } |
285 | |
286 | #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS |
287 | asmlinkage long SyS_fallocate(long fd, long mode, loff_t offset, loff_t len) |
288 | { |
289 | return SYSC_fallocate((int)fd, (int)mode, offset, len); |
290 | } |
291 | SYSCALL_ALIAS(sys_fallocate, SyS_fallocate); |
292 | #endif |
293 | |
294 | /* |
295 | * access() needs to use the real uid/gid, not the effective uid/gid. |
296 | * We do this by temporarily clearing all FS-related capabilities and |
297 | * switching the fsuid/fsgid around to the real ones. |
298 | */ |
299 | SYSCALL_DEFINE3(faccessat, int, dfd, const char __user *, filename, int, mode) |
300 | { |
301 | const struct cred *old_cred; |
302 | struct cred *override_cred; |
303 | struct path path; |
304 | struct inode *inode; |
305 | int res; |
306 | |
307 | if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ |
308 | return -EINVAL; |
309 | |
310 | override_cred = prepare_creds(); |
311 | if (!override_cred) |
312 | return -ENOMEM; |
313 | |
314 | override_cred->fsuid = override_cred->uid; |
315 | override_cred->fsgid = override_cred->gid; |
316 | |
317 | if (!issecure(SECURE_NO_SETUID_FIXUP)) { |
318 | /* Clear the capabilities if we switch to a non-root user */ |
319 | if (override_cred->uid) |
320 | cap_clear(override_cred->cap_effective); |
321 | else |
322 | override_cred->cap_effective = |
323 | override_cred->cap_permitted; |
324 | } |
325 | |
326 | old_cred = override_creds(override_cred); |
327 | |
328 | res = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path); |
329 | if (res) |
330 | goto out; |
331 | |
332 | inode = path.dentry->d_inode; |
333 | |
334 | if ((mode & MAY_EXEC) && S_ISREG(inode->i_mode)) { |
335 | /* |
336 | * MAY_EXEC on regular files is denied if the fs is mounted |
337 | * with the "noexec" flag. |
338 | */ |
339 | res = -EACCES; |
340 | if (path.mnt->mnt_flags & MNT_NOEXEC) |
341 | goto out_path_release; |
342 | } |
343 | |
344 | res = inode_permission(inode, mode | MAY_ACCESS); |
345 | /* SuS v2 requires we report a read only fs too */ |
346 | if (res || !(mode & S_IWOTH) || special_file(inode->i_mode)) |
347 | goto out_path_release; |
348 | /* |
349 | * This is a rare case where using __mnt_is_readonly() |
350 | * is OK without a mnt_want/drop_write() pair. Since |
351 | * no actual write to the fs is performed here, we do |
352 | * not need to telegraph to that to anyone. |
353 | * |
354 | * By doing this, we accept that this access is |
355 | * inherently racy and know that the fs may change |
356 | * state before we even see this result. |
357 | */ |
358 | if (__mnt_is_readonly(path.mnt)) |
359 | res = -EROFS; |
360 | |
361 | out_path_release: |
362 | path_put(&path); |
363 | out: |
364 | revert_creds(old_cred); |
365 | put_cred(override_cred); |
366 | return res; |
367 | } |
368 | |
369 | SYSCALL_DEFINE2(access, const char __user *, filename, int, mode) |
370 | { |
371 | return sys_faccessat(AT_FDCWD, filename, mode); |
372 | } |
373 | |
374 | SYSCALL_DEFINE1(chdir, const char __user *, filename) |
375 | { |
376 | struct path path; |
377 | int error; |
378 | |
379 | error = user_path_dir(filename, &path); |
380 | if (error) |
381 | goto out; |
382 | |
383 | error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR); |
384 | if (error) |
385 | goto dput_and_out; |
386 | |
387 | set_fs_pwd(current->fs, &path); |
388 | |
389 | dput_and_out: |
390 | path_put(&path); |
391 | out: |
392 | return error; |
393 | } |
394 | |
395 | SYSCALL_DEFINE1(fchdir, unsigned int, fd) |
396 | { |
397 | struct file *file; |
398 | struct inode *inode; |
399 | int error; |
400 | |
401 | error = -EBADF; |
402 | file = fget(fd); |
403 | if (!file) |
404 | goto out; |
405 | |
406 | inode = file->f_path.dentry->d_inode; |
407 | |
408 | error = -ENOTDIR; |
409 | if (!S_ISDIR(inode->i_mode)) |
410 | goto out_putf; |
411 | |
412 | error = inode_permission(inode, MAY_EXEC | MAY_CHDIR); |
413 | if (!error) |
414 | set_fs_pwd(current->fs, &file->f_path); |
415 | out_putf: |
416 | fput(file); |
417 | out: |
418 | return error; |
419 | } |
420 | |
421 | SYSCALL_DEFINE1(chroot, const char __user *, filename) |
422 | { |
423 | struct path path; |
424 | int error; |
425 | |
426 | error = user_path_dir(filename, &path); |
427 | if (error) |
428 | goto out; |
429 | |
430 | error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR); |
431 | if (error) |
432 | goto dput_and_out; |
433 | |
434 | error = -EPERM; |
435 | if (!capable(CAP_SYS_CHROOT)) |
436 | goto dput_and_out; |
437 | error = security_path_chroot(&path); |
438 | if (error) |
439 | goto dput_and_out; |
440 | |
441 | set_fs_root(current->fs, &path); |
442 | error = 0; |
443 | dput_and_out: |
444 | path_put(&path); |
445 | out: |
446 | return error; |
447 | } |
448 | |
449 | SYSCALL_DEFINE2(fchmod, unsigned int, fd, mode_t, mode) |
450 | { |
451 | struct inode * inode; |
452 | struct dentry * dentry; |
453 | struct file * file; |
454 | int err = -EBADF; |
455 | struct iattr newattrs; |
456 | |
457 | file = fget(fd); |
458 | if (!file) |
459 | goto out; |
460 | |
461 | dentry = file->f_path.dentry; |
462 | inode = dentry->d_inode; |
463 | |
464 | audit_inode(NULL, dentry); |
465 | |
466 | err = mnt_want_write_file(file); |
467 | if (err) |
468 | goto out_putf; |
469 | mutex_lock(&inode->i_mutex); |
470 | err = security_path_chmod(dentry, file->f_vfsmnt, mode); |
471 | if (err) |
472 | goto out_unlock; |
473 | if (mode == (mode_t) -1) |
474 | mode = inode->i_mode; |
475 | newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); |
476 | newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; |
477 | err = notify_change(dentry, &newattrs); |
478 | out_unlock: |
479 | mutex_unlock(&inode->i_mutex); |
480 | mnt_drop_write(file->f_path.mnt); |
481 | out_putf: |
482 | fput(file); |
483 | out: |
484 | return err; |
485 | } |
486 | |
487 | SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, mode_t, mode) |
488 | { |
489 | struct path path; |
490 | struct inode *inode; |
491 | int error; |
492 | struct iattr newattrs; |
493 | |
494 | error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path); |
495 | if (error) |
496 | goto out; |
497 | inode = path.dentry->d_inode; |
498 | |
499 | error = mnt_want_write(path.mnt); |
500 | if (error) |
501 | goto dput_and_out; |
502 | mutex_lock(&inode->i_mutex); |
503 | error = security_path_chmod(path.dentry, path.mnt, mode); |
504 | if (error) |
505 | goto out_unlock; |
506 | if (mode == (mode_t) -1) |
507 | mode = inode->i_mode; |
508 | newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); |
509 | newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; |
510 | error = notify_change(path.dentry, &newattrs); |
511 | out_unlock: |
512 | mutex_unlock(&inode->i_mutex); |
513 | mnt_drop_write(path.mnt); |
514 | dput_and_out: |
515 | path_put(&path); |
516 | out: |
517 | return error; |
518 | } |
519 | |
520 | SYSCALL_DEFINE2(chmod, const char __user *, filename, mode_t, mode) |
521 | { |
522 | return sys_fchmodat(AT_FDCWD, filename, mode); |
523 | } |
524 | |
525 | static int chown_common(struct path *path, uid_t user, gid_t group) |
526 | { |
527 | struct inode *inode = path->dentry->d_inode; |
528 | int error; |
529 | struct iattr newattrs; |
530 | |
531 | newattrs.ia_valid = ATTR_CTIME; |
532 | if (user != (uid_t) -1) { |
533 | newattrs.ia_valid |= ATTR_UID; |
534 | newattrs.ia_uid = user; |
535 | } |
536 | if (group != (gid_t) -1) { |
537 | newattrs.ia_valid |= ATTR_GID; |
538 | newattrs.ia_gid = group; |
539 | } |
540 | if (!S_ISDIR(inode->i_mode)) |
541 | newattrs.ia_valid |= |
542 | ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV; |
543 | mutex_lock(&inode->i_mutex); |
544 | error = security_path_chown(path, user, group); |
545 | if (!error) |
546 | error = notify_change(path->dentry, &newattrs); |
547 | mutex_unlock(&inode->i_mutex); |
548 | |
549 | return error; |
550 | } |
551 | |
552 | SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group) |
553 | { |
554 | struct path path; |
555 | int error; |
556 | |
557 | error = user_path(filename, &path); |
558 | if (error) |
559 | goto out; |
560 | error = mnt_want_write(path.mnt); |
561 | if (error) |
562 | goto out_release; |
563 | error = chown_common(&path, user, group); |
564 | mnt_drop_write(path.mnt); |
565 | out_release: |
566 | path_put(&path); |
567 | out: |
568 | return error; |
569 | } |
570 | |
571 | SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user, |
572 | gid_t, group, int, flag) |
573 | { |
574 | struct path path; |
575 | int error = -EINVAL; |
576 | int follow; |
577 | |
578 | if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0) |
579 | goto out; |
580 | |
581 | follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; |
582 | error = user_path_at(dfd, filename, follow, &path); |
583 | if (error) |
584 | goto out; |
585 | error = mnt_want_write(path.mnt); |
586 | if (error) |
587 | goto out_release; |
588 | error = chown_common(&path, user, group); |
589 | mnt_drop_write(path.mnt); |
590 | out_release: |
591 | path_put(&path); |
592 | out: |
593 | return error; |
594 | } |
595 | |
596 | SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group) |
597 | { |
598 | struct path path; |
599 | int error; |
600 | |
601 | error = user_lpath(filename, &path); |
602 | if (error) |
603 | goto out; |
604 | error = mnt_want_write(path.mnt); |
605 | if (error) |
606 | goto out_release; |
607 | error = chown_common(&path, user, group); |
608 | mnt_drop_write(path.mnt); |
609 | out_release: |
610 | path_put(&path); |
611 | out: |
612 | return error; |
613 | } |
614 | |
615 | SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) |
616 | { |
617 | struct file * file; |
618 | int error = -EBADF; |
619 | struct dentry * dentry; |
620 | |
621 | file = fget(fd); |
622 | if (!file) |
623 | goto out; |
624 | |
625 | error = mnt_want_write_file(file); |
626 | if (error) |
627 | goto out_fput; |
628 | dentry = file->f_path.dentry; |
629 | audit_inode(NULL, dentry); |
630 | error = chown_common(&file->f_path, user, group); |
631 | mnt_drop_write(file->f_path.mnt); |
632 | out_fput: |
633 | fput(file); |
634 | out: |
635 | return error; |
636 | } |
637 | |
638 | /* |
639 | * You have to be very careful that these write |
640 | * counts get cleaned up in error cases and |
641 | * upon __fput(). This should probably never |
642 | * be called outside of __dentry_open(). |
643 | */ |
644 | static inline int __get_file_write_access(struct inode *inode, |
645 | struct vfsmount *mnt) |
646 | { |
647 | int error; |
648 | error = get_write_access(inode); |
649 | if (error) |
650 | return error; |
651 | /* |
652 | * Do not take mount writer counts on |
653 | * special files since no writes to |
654 | * the mount itself will occur. |
655 | */ |
656 | if (!special_file(inode->i_mode)) { |
657 | /* |
658 | * Balanced in __fput() |
659 | */ |
660 | error = mnt_want_write(mnt); |
661 | if (error) |
662 | put_write_access(inode); |
663 | } |
664 | return error; |
665 | } |
666 | |
667 | static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt, |
668 | struct file *f, |
669 | int (*open)(struct inode *, struct file *), |
670 | const struct cred *cred) |
671 | { |
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 | inode = dentry->d_inode; |
678 | if (f->f_mode & FMODE_WRITE) { |
679 | error = __get_file_write_access(inode, mnt); |
680 | if (error) |
681 | goto cleanup_file; |
682 | if (!special_file(inode->i_mode)) |
683 | file_take_write(f); |
684 | } |
685 | |
686 | f->f_mapping = inode->i_mapping; |
687 | f->f_path.dentry = dentry; |
688 | f->f_path.mnt = mnt; |
689 | f->f_pos = 0; |
690 | f->f_op = fops_get(inode->i_fop); |
691 | file_sb_list_add(f, inode->i_sb); |
692 | |
693 | error = security_dentry_open(f, cred); |
694 | if (error) |
695 | goto cleanup_all; |
696 | |
697 | if (!open && f->f_op) |
698 | open = f->f_op->open; |
699 | if (open) { |
700 | error = open(inode, f); |
701 | if (error) |
702 | goto cleanup_all; |
703 | } |
704 | ima_counts_get(f); |
705 | |
706 | f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); |
707 | |
708 | file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); |
709 | |
710 | /* NB: we're sure to have correct a_ops only after f_op->open */ |
711 | if (f->f_flags & O_DIRECT) { |
712 | if (!f->f_mapping->a_ops || |
713 | ((!f->f_mapping->a_ops->direct_IO) && |
714 | (!f->f_mapping->a_ops->get_xip_mem))) { |
715 | fput(f); |
716 | f = ERR_PTR(-EINVAL); |
717 | } |
718 | } |
719 | |
720 | return f; |
721 | |
722 | cleanup_all: |
723 | fops_put(f->f_op); |
724 | if (f->f_mode & FMODE_WRITE) { |
725 | put_write_access(inode); |
726 | if (!special_file(inode->i_mode)) { |
727 | /* |
728 | * We don't consider this a real |
729 | * mnt_want/drop_write() pair |
730 | * because it all happenend right |
731 | * here, so just reset the state. |
732 | */ |
733 | file_reset_write(f); |
734 | mnt_drop_write(mnt); |
735 | } |
736 | } |
737 | file_sb_list_del(f); |
738 | f->f_path.dentry = NULL; |
739 | f->f_path.mnt = NULL; |
740 | cleanup_file: |
741 | put_filp(f); |
742 | dput(dentry); |
743 | mntput(mnt); |
744 | return ERR_PTR(error); |
745 | } |
746 | |
747 | /** |
748 | * lookup_instantiate_filp - instantiates the open intent filp |
749 | * @nd: pointer to nameidata |
750 | * @dentry: pointer to dentry |
751 | * @open: open callback |
752 | * |
753 | * Helper for filesystems that want to use lookup open intents and pass back |
754 | * a fully instantiated struct file to the caller. |
755 | * This function is meant to be called from within a filesystem's |
756 | * lookup method. |
757 | * Beware of calling it for non-regular files! Those ->open methods might block |
758 | * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo, |
759 | * leading to a deadlock, as nobody can open that fifo anymore, because |
760 | * another process to open fifo will block on locked parent when doing lookup). |
761 | * Note that in case of error, nd->intent.open.file is destroyed, but the |
762 | * path information remains valid. |
763 | * If the open callback is set to NULL, then the standard f_op->open() |
764 | * filesystem callback is substituted. |
765 | */ |
766 | struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry, |
767 | int (*open)(struct inode *, struct file *)) |
768 | { |
769 | const struct cred *cred = current_cred(); |
770 | |
771 | if (IS_ERR(nd->intent.open.file)) |
772 | goto out; |
773 | if (IS_ERR(dentry)) |
774 | goto out_err; |
775 | nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt), |
776 | nd->intent.open.file, |
777 | open, cred); |
778 | out: |
779 | return nd->intent.open.file; |
780 | out_err: |
781 | release_open_intent(nd); |
782 | nd->intent.open.file = (struct file *)dentry; |
783 | goto out; |
784 | } |
785 | EXPORT_SYMBOL_GPL(lookup_instantiate_filp); |
786 | |
787 | /** |
788 | * nameidata_to_filp - convert a nameidata to an open filp. |
789 | * @nd: pointer to nameidata |
790 | * @flags: open flags |
791 | * |
792 | * Note that this function destroys the original nameidata |
793 | */ |
794 | struct file *nameidata_to_filp(struct nameidata *nd) |
795 | { |
796 | const struct cred *cred = current_cred(); |
797 | struct file *filp; |
798 | |
799 | /* Pick up the filp from the open intent */ |
800 | filp = nd->intent.open.file; |
801 | nd->intent.open.file = NULL; |
802 | |
803 | /* Has the filesystem initialised the file for us? */ |
804 | if (filp->f_path.dentry == NULL) { |
805 | path_get(&nd->path); |
806 | filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp, |
807 | NULL, cred); |
808 | } |
809 | return filp; |
810 | } |
811 | |
812 | /* |
813 | * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an |
814 | * error. |
815 | */ |
816 | struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags, |
817 | const struct cred *cred) |
818 | { |
819 | int error; |
820 | struct file *f; |
821 | |
822 | validate_creds(cred); |
823 | |
824 | /* |
825 | * We must always pass in a valid mount pointer. Historically |
826 | * callers got away with not passing it, but we must enforce this at |
827 | * the earliest possible point now to avoid strange problems deep in the |
828 | * filesystem stack. |
829 | */ |
830 | if (!mnt) { |
831 | printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__); |
832 | dump_stack(); |
833 | return ERR_PTR(-EINVAL); |
834 | } |
835 | |
836 | error = -ENFILE; |
837 | f = get_empty_filp(); |
838 | if (f == NULL) { |
839 | dput(dentry); |
840 | mntput(mnt); |
841 | return ERR_PTR(error); |
842 | } |
843 | |
844 | f->f_flags = flags; |
845 | return __dentry_open(dentry, mnt, f, NULL, cred); |
846 | } |
847 | EXPORT_SYMBOL(dentry_open); |
848 | |
849 | static void __put_unused_fd(struct files_struct *files, unsigned int fd) |
850 | { |
851 | struct fdtable *fdt = files_fdtable(files); |
852 | __FD_CLR(fd, fdt->open_fds); |
853 | if (fd < files->next_fd) |
854 | files->next_fd = fd; |
855 | } |
856 | |
857 | void put_unused_fd(unsigned int fd) |
858 | { |
859 | struct files_struct *files = current->files; |
860 | spin_lock(&files->file_lock); |
861 | __put_unused_fd(files, fd); |
862 | spin_unlock(&files->file_lock); |
863 | } |
864 | |
865 | EXPORT_SYMBOL(put_unused_fd); |
866 | |
867 | /* |
868 | * Install a file pointer in the fd array. |
869 | * |
870 | * The VFS is full of places where we drop the files lock between |
871 | * setting the open_fds bitmap and installing the file in the file |
872 | * array. At any such point, we are vulnerable to a dup2() race |
873 | * installing a file in the array before us. We need to detect this and |
874 | * fput() the struct file we are about to overwrite in this case. |
875 | * |
876 | * It should never happen - if we allow dup2() do it, _really_ bad things |
877 | * will follow. |
878 | */ |
879 | |
880 | void fd_install(unsigned int fd, struct file *file) |
881 | { |
882 | struct files_struct *files = current->files; |
883 | struct fdtable *fdt; |
884 | spin_lock(&files->file_lock); |
885 | fdt = files_fdtable(files); |
886 | BUG_ON(fdt->fd[fd] != NULL); |
887 | rcu_assign_pointer(fdt->fd[fd], file); |
888 | spin_unlock(&files->file_lock); |
889 | } |
890 | |
891 | EXPORT_SYMBOL(fd_install); |
892 | |
893 | long do_sys_open(int dfd, const char __user *filename, int flags, int mode) |
894 | { |
895 | char *tmp = getname(filename); |
896 | int fd = PTR_ERR(tmp); |
897 | |
898 | if (!IS_ERR(tmp)) { |
899 | fd = get_unused_fd_flags(flags); |
900 | if (fd >= 0) { |
901 | struct file *f = do_filp_open(dfd, tmp, flags, mode, 0); |
902 | if (IS_ERR(f)) { |
903 | put_unused_fd(fd); |
904 | fd = PTR_ERR(f); |
905 | } else { |
906 | fsnotify_open(f); |
907 | fd_install(fd, f); |
908 | } |
909 | } |
910 | putname(tmp); |
911 | } |
912 | return fd; |
913 | } |
914 | |
915 | SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, int, mode) |
916 | { |
917 | long ret; |
918 | |
919 | if (force_o_largefile()) |
920 | flags |= O_LARGEFILE; |
921 | |
922 | ret = do_sys_open(AT_FDCWD, filename, flags, mode); |
923 | /* avoid REGPARM breakage on x86: */ |
924 | asmlinkage_protect(3, ret, filename, flags, mode); |
925 | return ret; |
926 | } |
927 | |
928 | SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, |
929 | int, mode) |
930 | { |
931 | long ret; |
932 | |
933 | if (force_o_largefile()) |
934 | flags |= O_LARGEFILE; |
935 | |
936 | ret = do_sys_open(dfd, filename, flags, mode); |
937 | /* avoid REGPARM breakage on x86: */ |
938 | asmlinkage_protect(4, ret, dfd, filename, flags, mode); |
939 | return ret; |
940 | } |
941 | |
942 | #ifndef __alpha__ |
943 | |
944 | /* |
945 | * For backward compatibility? Maybe this should be moved |
946 | * into arch/i386 instead? |
947 | */ |
948 | SYSCALL_DEFINE2(creat, const char __user *, pathname, int, mode) |
949 | { |
950 | return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode); |
951 | } |
952 | |
953 | #endif |
954 | |
955 | /* |
956 | * "id" is the POSIX thread ID. We use the |
957 | * files pointer for this.. |
958 | */ |
959 | int filp_close(struct file *filp, fl_owner_t id) |
960 | { |
961 | int retval = 0; |
962 | |
963 | if (!file_count(filp)) { |
964 | printk(KERN_ERR "VFS: Close: file count is 0\n"); |
965 | return 0; |
966 | } |
967 | |
968 | if (filp->f_op && filp->f_op->flush) |
969 | retval = filp->f_op->flush(filp, id); |
970 | |
971 | dnotify_flush(filp, id); |
972 | locks_remove_posix(filp, id); |
973 | fput(filp); |
974 | return retval; |
975 | } |
976 | |
977 | EXPORT_SYMBOL(filp_close); |
978 | |
979 | /* |
980 | * Careful here! We test whether the file pointer is NULL before |
981 | * releasing the fd. This ensures that one clone task can't release |
982 | * an fd while another clone is opening it. |
983 | */ |
984 | SYSCALL_DEFINE1(close, unsigned int, fd) |
985 | { |
986 | struct file * filp; |
987 | struct files_struct *files = current->files; |
988 | struct fdtable *fdt; |
989 | int retval; |
990 | |
991 | spin_lock(&files->file_lock); |
992 | fdt = files_fdtable(files); |
993 | if (fd >= fdt->max_fds) |
994 | goto out_unlock; |
995 | filp = fdt->fd[fd]; |
996 | if (!filp) |
997 | goto out_unlock; |
998 | rcu_assign_pointer(fdt->fd[fd], NULL); |
999 | FD_CLR(fd, fdt->close_on_exec); |
1000 | __put_unused_fd(files, fd); |
1001 | spin_unlock(&files->file_lock); |
1002 | retval = filp_close(filp, files); |
1003 | |
1004 | /* can't restart close syscall because file table entry was cleared */ |
1005 | if (unlikely(retval == -ERESTARTSYS || |
1006 | retval == -ERESTARTNOINTR || |
1007 | retval == -ERESTARTNOHAND || |
1008 | retval == -ERESTART_RESTARTBLOCK)) |
1009 | retval = -EINTR; |
1010 | |
1011 | return retval; |
1012 | |
1013 | out_unlock: |
1014 | spin_unlock(&files->file_lock); |
1015 | return -EBADF; |
1016 | } |
1017 | EXPORT_SYMBOL(sys_close); |
1018 | |
1019 | /* |
1020 | * This routine simulates a hangup on the tty, to arrange that users |
1021 | * are given clean terminals at login time. |
1022 | */ |
1023 | SYSCALL_DEFINE0(vhangup) |
1024 | { |
1025 | if (capable(CAP_SYS_TTY_CONFIG)) { |
1026 | tty_vhangup_self(); |
1027 | return 0; |
1028 | } |
1029 | return -EPERM; |
1030 | } |
1031 | |
1032 | /* |
1033 | * Called when an inode is about to be open. |
1034 | * We use this to disallow opening large files on 32bit systems if |
1035 | * the caller didn't specify O_LARGEFILE. On 64bit systems we force |
1036 | * on this flag in sys_open. |
1037 | */ |
1038 | int generic_file_open(struct inode * inode, struct file * filp) |
1039 | { |
1040 | if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS) |
1041 | return -EOVERFLOW; |
1042 | return 0; |
1043 | } |
1044 | |
1045 | EXPORT_SYMBOL(generic_file_open); |
1046 | |
1047 | /* |
1048 | * This is used by subsystems that don't want seekable |
1049 | * file descriptors. The function is not supposed to ever fail, the only |
1050 | * reason it returns an 'int' and not 'void' is so that it can be plugged |
1051 | * directly into file_operations structure. |
1052 | */ |
1053 | int nonseekable_open(struct inode *inode, struct file *filp) |
1054 | { |
1055 | filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE); |
1056 | return 0; |
1057 | } |
1058 | |
1059 | EXPORT_SYMBOL(nonseekable_open); |
1060 |
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