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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 | static int chmod_common(struct path *path, umode_t mode) |
450 | { |
451 | struct inode *inode = path->dentry->d_inode; |
452 | struct iattr newattrs; |
453 | int error; |
454 | |
455 | error = mnt_want_write(path->mnt); |
456 | if (error) |
457 | return error; |
458 | mutex_lock(&inode->i_mutex); |
459 | error = security_path_chmod(path, mode); |
460 | if (error) |
461 | goto out_unlock; |
462 | newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); |
463 | newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; |
464 | error = notify_change(path->dentry, &newattrs); |
465 | out_unlock: |
466 | mutex_unlock(&inode->i_mutex); |
467 | mnt_drop_write(path->mnt); |
468 | return error; |
469 | } |
470 | |
471 | SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode) |
472 | { |
473 | struct file * file; |
474 | int err = -EBADF; |
475 | |
476 | file = fget(fd); |
477 | if (file) { |
478 | audit_inode(NULL, file->f_path.dentry); |
479 | err = chmod_common(&file->f_path, mode); |
480 | fput(file); |
481 | } |
482 | return err; |
483 | } |
484 | |
485 | SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode) |
486 | { |
487 | struct path path; |
488 | int error; |
489 | |
490 | error = user_path_at(dfd, filename, LOOKUP_FOLLOW, &path); |
491 | if (!error) { |
492 | error = chmod_common(&path, mode); |
493 | path_put(&path); |
494 | } |
495 | return error; |
496 | } |
497 | |
498 | SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode) |
499 | { |
500 | return sys_fchmodat(AT_FDCWD, filename, mode); |
501 | } |
502 | |
503 | static int chown_common(struct path *path, uid_t user, gid_t group) |
504 | { |
505 | struct inode *inode = path->dentry->d_inode; |
506 | int error; |
507 | struct iattr newattrs; |
508 | |
509 | newattrs.ia_valid = ATTR_CTIME; |
510 | if (user != (uid_t) -1) { |
511 | newattrs.ia_valid |= ATTR_UID; |
512 | newattrs.ia_uid = user; |
513 | } |
514 | if (group != (gid_t) -1) { |
515 | newattrs.ia_valid |= ATTR_GID; |
516 | newattrs.ia_gid = group; |
517 | } |
518 | if (!S_ISDIR(inode->i_mode)) |
519 | newattrs.ia_valid |= |
520 | ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV; |
521 | mutex_lock(&inode->i_mutex); |
522 | error = security_path_chown(path, user, group); |
523 | if (!error) |
524 | error = notify_change(path->dentry, &newattrs); |
525 | mutex_unlock(&inode->i_mutex); |
526 | |
527 | return error; |
528 | } |
529 | |
530 | SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group) |
531 | { |
532 | struct path path; |
533 | int error; |
534 | |
535 | error = user_path(filename, &path); |
536 | if (error) |
537 | goto out; |
538 | error = mnt_want_write(path.mnt); |
539 | if (error) |
540 | goto out_release; |
541 | error = chown_common(&path, user, group); |
542 | mnt_drop_write(path.mnt); |
543 | out_release: |
544 | path_put(&path); |
545 | out: |
546 | return error; |
547 | } |
548 | |
549 | SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user, |
550 | gid_t, group, int, flag) |
551 | { |
552 | struct path path; |
553 | int error = -EINVAL; |
554 | int lookup_flags; |
555 | |
556 | if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH)) != 0) |
557 | goto out; |
558 | |
559 | lookup_flags = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; |
560 | if (flag & AT_EMPTY_PATH) |
561 | lookup_flags |= LOOKUP_EMPTY; |
562 | error = user_path_at(dfd, filename, lookup_flags, &path); |
563 | if (error) |
564 | goto out; |
565 | error = mnt_want_write(path.mnt); |
566 | if (error) |
567 | goto out_release; |
568 | error = chown_common(&path, user, group); |
569 | mnt_drop_write(path.mnt); |
570 | out_release: |
571 | path_put(&path); |
572 | out: |
573 | return error; |
574 | } |
575 | |
576 | SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group) |
577 | { |
578 | struct path path; |
579 | int error; |
580 | |
581 | error = user_lpath(filename, &path); |
582 | if (error) |
583 | goto out; |
584 | error = mnt_want_write(path.mnt); |
585 | if (error) |
586 | goto out_release; |
587 | error = chown_common(&path, user, group); |
588 | mnt_drop_write(path.mnt); |
589 | out_release: |
590 | path_put(&path); |
591 | out: |
592 | return error; |
593 | } |
594 | |
595 | SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) |
596 | { |
597 | struct file * file; |
598 | int error = -EBADF; |
599 | struct dentry * dentry; |
600 | |
601 | file = fget(fd); |
602 | if (!file) |
603 | goto out; |
604 | |
605 | error = mnt_want_write_file(file); |
606 | if (error) |
607 | goto out_fput; |
608 | dentry = file->f_path.dentry; |
609 | audit_inode(NULL, dentry); |
610 | error = chown_common(&file->f_path, user, group); |
611 | mnt_drop_write_file(file); |
612 | out_fput: |
613 | fput(file); |
614 | out: |
615 | return error; |
616 | } |
617 | |
618 | /* |
619 | * You have to be very careful that these write |
620 | * counts get cleaned up in error cases and |
621 | * upon __fput(). This should probably never |
622 | * be called outside of __dentry_open(). |
623 | */ |
624 | static inline int __get_file_write_access(struct inode *inode, |
625 | struct vfsmount *mnt) |
626 | { |
627 | int error; |
628 | error = get_write_access(inode); |
629 | if (error) |
630 | return error; |
631 | /* |
632 | * Do not take mount writer counts on |
633 | * special files since no writes to |
634 | * the mount itself will occur. |
635 | */ |
636 | if (!special_file(inode->i_mode)) { |
637 | /* |
638 | * Balanced in __fput() |
639 | */ |
640 | error = mnt_want_write(mnt); |
641 | if (error) |
642 | put_write_access(inode); |
643 | } |
644 | return error; |
645 | } |
646 | |
647 | static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt, |
648 | struct file *f, |
649 | int (*open)(struct inode *, struct file *), |
650 | const struct cred *cred) |
651 | { |
652 | static const struct file_operations empty_fops = {}; |
653 | struct inode *inode; |
654 | int error; |
655 | |
656 | f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK | |
657 | FMODE_PREAD | FMODE_PWRITE; |
658 | |
659 | if (unlikely(f->f_flags & O_PATH)) |
660 | f->f_mode = FMODE_PATH; |
661 | |
662 | inode = dentry->d_inode; |
663 | if (f->f_mode & FMODE_WRITE) { |
664 | error = __get_file_write_access(inode, mnt); |
665 | if (error) |
666 | goto cleanup_file; |
667 | if (!special_file(inode->i_mode)) |
668 | file_take_write(f); |
669 | } |
670 | |
671 | f->f_mapping = inode->i_mapping; |
672 | f->f_path.dentry = dentry; |
673 | f->f_path.mnt = mnt; |
674 | f->f_pos = 0; |
675 | file_sb_list_add(f, inode->i_sb); |
676 | |
677 | if (unlikely(f->f_mode & FMODE_PATH)) { |
678 | f->f_op = &empty_fops; |
679 | return f; |
680 | } |
681 | |
682 | f->f_op = fops_get(inode->i_fop); |
683 | |
684 | error = security_dentry_open(f, cred); |
685 | if (error) |
686 | goto cleanup_all; |
687 | |
688 | error = break_lease(inode, f->f_flags); |
689 | if (error) |
690 | goto cleanup_all; |
691 | |
692 | if (!open && f->f_op) |
693 | open = f->f_op->open; |
694 | if (open) { |
695 | error = open(inode, f); |
696 | if (error) |
697 | goto cleanup_all; |
698 | } |
699 | if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ) |
700 | i_readcount_inc(inode); |
701 | |
702 | f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); |
703 | |
704 | file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); |
705 | |
706 | /* NB: we're sure to have correct a_ops only after f_op->open */ |
707 | if (f->f_flags & O_DIRECT) { |
708 | if (!f->f_mapping->a_ops || |
709 | ((!f->f_mapping->a_ops->direct_IO) && |
710 | (!f->f_mapping->a_ops->get_xip_mem))) { |
711 | fput(f); |
712 | f = ERR_PTR(-EINVAL); |
713 | } |
714 | } |
715 | |
716 | return f; |
717 | |
718 | cleanup_all: |
719 | fops_put(f->f_op); |
720 | if (f->f_mode & FMODE_WRITE) { |
721 | put_write_access(inode); |
722 | if (!special_file(inode->i_mode)) { |
723 | /* |
724 | * We don't consider this a real |
725 | * mnt_want/drop_write() pair |
726 | * because it all happenend right |
727 | * here, so just reset the state. |
728 | */ |
729 | file_reset_write(f); |
730 | mnt_drop_write(mnt); |
731 | } |
732 | } |
733 | file_sb_list_del(f); |
734 | f->f_path.dentry = NULL; |
735 | f->f_path.mnt = NULL; |
736 | cleanup_file: |
737 | put_filp(f); |
738 | dput(dentry); |
739 | mntput(mnt); |
740 | return ERR_PTR(error); |
741 | } |
742 | |
743 | /** |
744 | * lookup_instantiate_filp - instantiates the open intent filp |
745 | * @nd: pointer to nameidata |
746 | * @dentry: pointer to dentry |
747 | * @open: open callback |
748 | * |
749 | * Helper for filesystems that want to use lookup open intents and pass back |
750 | * a fully instantiated struct file to the caller. |
751 | * This function is meant to be called from within a filesystem's |
752 | * lookup method. |
753 | * Beware of calling it for non-regular files! Those ->open methods might block |
754 | * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo, |
755 | * leading to a deadlock, as nobody can open that fifo anymore, because |
756 | * another process to open fifo will block on locked parent when doing lookup). |
757 | * Note that in case of error, nd->intent.open.file is destroyed, but the |
758 | * path information remains valid. |
759 | * If the open callback is set to NULL, then the standard f_op->open() |
760 | * filesystem callback is substituted. |
761 | */ |
762 | struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry, |
763 | int (*open)(struct inode *, struct file *)) |
764 | { |
765 | const struct cred *cred = current_cred(); |
766 | |
767 | if (IS_ERR(nd->intent.open.file)) |
768 | goto out; |
769 | if (IS_ERR(dentry)) |
770 | goto out_err; |
771 | nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt), |
772 | nd->intent.open.file, |
773 | open, cred); |
774 | out: |
775 | return nd->intent.open.file; |
776 | out_err: |
777 | release_open_intent(nd); |
778 | nd->intent.open.file = ERR_CAST(dentry); |
779 | goto out; |
780 | } |
781 | EXPORT_SYMBOL_GPL(lookup_instantiate_filp); |
782 | |
783 | /** |
784 | * nameidata_to_filp - convert a nameidata to an open filp. |
785 | * @nd: pointer to nameidata |
786 | * @flags: open flags |
787 | * |
788 | * Note that this function destroys the original nameidata |
789 | */ |
790 | struct file *nameidata_to_filp(struct nameidata *nd) |
791 | { |
792 | const struct cred *cred = current_cred(); |
793 | struct file *filp; |
794 | |
795 | /* Pick up the filp from the open intent */ |
796 | filp = nd->intent.open.file; |
797 | nd->intent.open.file = NULL; |
798 | |
799 | /* Has the filesystem initialised the file for us? */ |
800 | if (filp->f_path.dentry == NULL) { |
801 | path_get(&nd->path); |
802 | filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp, |
803 | NULL, cred); |
804 | } |
805 | return filp; |
806 | } |
807 | |
808 | /* |
809 | * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an |
810 | * error. |
811 | */ |
812 | struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags, |
813 | const struct cred *cred) |
814 | { |
815 | int error; |
816 | struct file *f; |
817 | |
818 | validate_creds(cred); |
819 | |
820 | /* We must always pass in a valid mount pointer. */ |
821 | BUG_ON(!mnt); |
822 | |
823 | error = -ENFILE; |
824 | f = get_empty_filp(); |
825 | if (f == NULL) { |
826 | dput(dentry); |
827 | mntput(mnt); |
828 | return ERR_PTR(error); |
829 | } |
830 | |
831 | f->f_flags = flags; |
832 | return __dentry_open(dentry, mnt, f, NULL, cred); |
833 | } |
834 | EXPORT_SYMBOL(dentry_open); |
835 | |
836 | static void __put_unused_fd(struct files_struct *files, unsigned int fd) |
837 | { |
838 | struct fdtable *fdt = files_fdtable(files); |
839 | __clear_open_fd(fd, fdt); |
840 | if (fd < files->next_fd) |
841 | files->next_fd = fd; |
842 | } |
843 | |
844 | void put_unused_fd(unsigned int fd) |
845 | { |
846 | struct files_struct *files = current->files; |
847 | spin_lock(&files->file_lock); |
848 | __put_unused_fd(files, fd); |
849 | spin_unlock(&files->file_lock); |
850 | } |
851 | |
852 | EXPORT_SYMBOL(put_unused_fd); |
853 | |
854 | /* |
855 | * Install a file pointer in the fd array. |
856 | * |
857 | * The VFS is full of places where we drop the files lock between |
858 | * setting the open_fds bitmap and installing the file in the file |
859 | * array. At any such point, we are vulnerable to a dup2() race |
860 | * installing a file in the array before us. We need to detect this and |
861 | * fput() the struct file we are about to overwrite in this case. |
862 | * |
863 | * It should never happen - if we allow dup2() do it, _really_ bad things |
864 | * will follow. |
865 | */ |
866 | |
867 | void fd_install(unsigned int fd, struct file *file) |
868 | { |
869 | struct files_struct *files = current->files; |
870 | struct fdtable *fdt; |
871 | spin_lock(&files->file_lock); |
872 | fdt = files_fdtable(files); |
873 | BUG_ON(fdt->fd[fd] != NULL); |
874 | rcu_assign_pointer(fdt->fd[fd], file); |
875 | spin_unlock(&files->file_lock); |
876 | } |
877 | |
878 | EXPORT_SYMBOL(fd_install); |
879 | |
880 | static inline int build_open_flags(int flags, umode_t mode, struct open_flags *op) |
881 | { |
882 | int lookup_flags = 0; |
883 | int acc_mode; |
884 | |
885 | if (!(flags & O_CREAT)) |
886 | mode = 0; |
887 | op->mode = mode; |
888 | |
889 | /* Must never be set by userspace */ |
890 | flags &= ~FMODE_NONOTIFY; |
891 | |
892 | /* |
893 | * O_SYNC is implemented as __O_SYNC|O_DSYNC. As many places only |
894 | * check for O_DSYNC if the need any syncing at all we enforce it's |
895 | * always set instead of having to deal with possibly weird behaviour |
896 | * for malicious applications setting only __O_SYNC. |
897 | */ |
898 | if (flags & __O_SYNC) |
899 | flags |= O_DSYNC; |
900 | |
901 | /* |
902 | * If we have O_PATH in the open flag. Then we |
903 | * cannot have anything other than the below set of flags |
904 | */ |
905 | if (flags & O_PATH) { |
906 | flags &= O_DIRECTORY | O_NOFOLLOW | O_PATH; |
907 | acc_mode = 0; |
908 | } else { |
909 | acc_mode = MAY_OPEN | ACC_MODE(flags); |
910 | } |
911 | |
912 | op->open_flag = flags; |
913 | |
914 | /* O_TRUNC implies we need access checks for write permissions */ |
915 | if (flags & O_TRUNC) |
916 | acc_mode |= MAY_WRITE; |
917 | |
918 | /* Allow the LSM permission hook to distinguish append |
919 | access from general write access. */ |
920 | if (flags & O_APPEND) |
921 | acc_mode |= MAY_APPEND; |
922 | |
923 | op->acc_mode = acc_mode; |
924 | |
925 | op->intent = flags & O_PATH ? 0 : LOOKUP_OPEN; |
926 | |
927 | if (flags & O_CREAT) { |
928 | op->intent |= LOOKUP_CREATE; |
929 | if (flags & O_EXCL) |
930 | op->intent |= LOOKUP_EXCL; |
931 | } |
932 | |
933 | if (flags & O_DIRECTORY) |
934 | lookup_flags |= LOOKUP_DIRECTORY; |
935 | if (!(flags & O_NOFOLLOW)) |
936 | lookup_flags |= LOOKUP_FOLLOW; |
937 | return lookup_flags; |
938 | } |
939 | |
940 | /** |
941 | * filp_open - open file and return file pointer |
942 | * |
943 | * @filename: path to open |
944 | * @flags: open flags as per the open(2) second argument |
945 | * @mode: mode for the new file if O_CREAT is set, else ignored |
946 | * |
947 | * This is the helper to open a file from kernelspace if you really |
948 | * have to. But in generally you should not do this, so please move |
949 | * along, nothing to see here.. |
950 | */ |
951 | struct file *filp_open(const char *filename, int flags, umode_t mode) |
952 | { |
953 | struct open_flags op; |
954 | int lookup = build_open_flags(flags, mode, &op); |
955 | return do_filp_open(AT_FDCWD, filename, &op, lookup); |
956 | } |
957 | EXPORT_SYMBOL(filp_open); |
958 | |
959 | struct file *file_open_root(struct dentry *dentry, struct vfsmount *mnt, |
960 | const char *filename, int flags) |
961 | { |
962 | struct open_flags op; |
963 | int lookup = build_open_flags(flags, 0, &op); |
964 | if (flags & O_CREAT) |
965 | return ERR_PTR(-EINVAL); |
966 | if (!filename && (flags & O_DIRECTORY)) |
967 | if (!dentry->d_inode->i_op->lookup) |
968 | return ERR_PTR(-ENOTDIR); |
969 | return do_file_open_root(dentry, mnt, filename, &op, lookup); |
970 | } |
971 | EXPORT_SYMBOL(file_open_root); |
972 | |
973 | long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode) |
974 | { |
975 | struct open_flags op; |
976 | int lookup = build_open_flags(flags, mode, &op); |
977 | char *tmp = getname(filename); |
978 | int fd = PTR_ERR(tmp); |
979 | |
980 | if (!IS_ERR(tmp)) { |
981 | fd = get_unused_fd_flags(flags); |
982 | if (fd >= 0) { |
983 | struct file *f = do_filp_open(dfd, tmp, &op, lookup); |
984 | if (IS_ERR(f)) { |
985 | put_unused_fd(fd); |
986 | fd = PTR_ERR(f); |
987 | } else { |
988 | fsnotify_open(f); |
989 | fd_install(fd, f); |
990 | } |
991 | } |
992 | putname(tmp); |
993 | } |
994 | return fd; |
995 | } |
996 | |
997 | SYSCALL_DEFINE3(open, const char __user *, filename, int, flags, umode_t, mode) |
998 | { |
999 | long ret; |
1000 | |
1001 | if (force_o_largefile()) |
1002 | flags |= O_LARGEFILE; |
1003 | |
1004 | ret = do_sys_open(AT_FDCWD, filename, flags, mode); |
1005 | /* avoid REGPARM breakage on x86: */ |
1006 | asmlinkage_protect(3, ret, filename, flags, mode); |
1007 | return ret; |
1008 | } |
1009 | |
1010 | SYSCALL_DEFINE4(openat, int, dfd, const char __user *, filename, int, flags, |
1011 | umode_t, mode) |
1012 | { |
1013 | long ret; |
1014 | |
1015 | if (force_o_largefile()) |
1016 | flags |= O_LARGEFILE; |
1017 | |
1018 | ret = do_sys_open(dfd, filename, flags, mode); |
1019 | /* avoid REGPARM breakage on x86: */ |
1020 | asmlinkage_protect(4, ret, dfd, filename, flags, mode); |
1021 | return ret; |
1022 | } |
1023 | |
1024 | #ifndef __alpha__ |
1025 | |
1026 | /* |
1027 | * For backward compatibility? Maybe this should be moved |
1028 | * into arch/i386 instead? |
1029 | */ |
1030 | SYSCALL_DEFINE2(creat, const char __user *, pathname, umode_t, mode) |
1031 | { |
1032 | return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode); |
1033 | } |
1034 | |
1035 | #endif |
1036 | |
1037 | /* |
1038 | * "id" is the POSIX thread ID. We use the |
1039 | * files pointer for this.. |
1040 | */ |
1041 | int filp_close(struct file *filp, fl_owner_t id) |
1042 | { |
1043 | int retval = 0; |
1044 | |
1045 | if (!file_count(filp)) { |
1046 | printk(KERN_ERR "VFS: Close: file count is 0\n"); |
1047 | return 0; |
1048 | } |
1049 | |
1050 | if (filp->f_op && filp->f_op->flush) |
1051 | retval = filp->f_op->flush(filp, id); |
1052 | |
1053 | if (likely(!(filp->f_mode & FMODE_PATH))) { |
1054 | dnotify_flush(filp, id); |
1055 | locks_remove_posix(filp, id); |
1056 | } |
1057 | fput(filp); |
1058 | return retval; |
1059 | } |
1060 | |
1061 | EXPORT_SYMBOL(filp_close); |
1062 | |
1063 | /* |
1064 | * Careful here! We test whether the file pointer is NULL before |
1065 | * releasing the fd. This ensures that one clone task can't release |
1066 | * an fd while another clone is opening it. |
1067 | */ |
1068 | SYSCALL_DEFINE1(close, unsigned int, fd) |
1069 | { |
1070 | struct file * filp; |
1071 | struct files_struct *files = current->files; |
1072 | struct fdtable *fdt; |
1073 | int retval; |
1074 | |
1075 | spin_lock(&files->file_lock); |
1076 | fdt = files_fdtable(files); |
1077 | if (fd >= fdt->max_fds) |
1078 | goto out_unlock; |
1079 | filp = fdt->fd[fd]; |
1080 | if (!filp) |
1081 | goto out_unlock; |
1082 | rcu_assign_pointer(fdt->fd[fd], NULL); |
1083 | __clear_close_on_exec(fd, fdt); |
1084 | __put_unused_fd(files, fd); |
1085 | spin_unlock(&files->file_lock); |
1086 | retval = filp_close(filp, files); |
1087 | |
1088 | /* can't restart close syscall because file table entry was cleared */ |
1089 | if (unlikely(retval == -ERESTARTSYS || |
1090 | retval == -ERESTARTNOINTR || |
1091 | retval == -ERESTARTNOHAND || |
1092 | retval == -ERESTART_RESTARTBLOCK)) |
1093 | retval = -EINTR; |
1094 | |
1095 | return retval; |
1096 | |
1097 | out_unlock: |
1098 | spin_unlock(&files->file_lock); |
1099 | return -EBADF; |
1100 | } |
1101 | EXPORT_SYMBOL(sys_close); |
1102 | |
1103 | /* |
1104 | * This routine simulates a hangup on the tty, to arrange that users |
1105 | * are given clean terminals at login time. |
1106 | */ |
1107 | SYSCALL_DEFINE0(vhangup) |
1108 | { |
1109 | if (capable(CAP_SYS_TTY_CONFIG)) { |
1110 | tty_vhangup_self(); |
1111 | return 0; |
1112 | } |
1113 | return -EPERM; |
1114 | } |
1115 | |
1116 | /* |
1117 | * Called when an inode is about to be open. |
1118 | * We use this to disallow opening large files on 32bit systems if |
1119 | * the caller didn't specify O_LARGEFILE. On 64bit systems we force |
1120 | * on this flag in sys_open. |
1121 | */ |
1122 | int generic_file_open(struct inode * inode, struct file * filp) |
1123 | { |
1124 | if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS) |
1125 | return -EOVERFLOW; |
1126 | return 0; |
1127 | } |
1128 | |
1129 | EXPORT_SYMBOL(generic_file_open); |
1130 | |
1131 | /* |
1132 | * This is used by subsystems that don't want seekable |
1133 | * file descriptors. The function is not supposed to ever fail, the only |
1134 | * reason it returns an 'int' and not 'void' is so that it can be plugged |
1135 | * directly into file_operations structure. |
1136 | */ |
1137 | int nonseekable_open(struct inode *inode, struct file *filp) |
1138 | { |
1139 | filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE); |
1140 | return 0; |
1141 | } |
1142 | |
1143 | EXPORT_SYMBOL(nonseekable_open); |
1144 |
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