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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 && !(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 | filp = __dentry_open(nd->path.dentry, nd->path.mnt, filp, |
791 | NULL, cred); |
792 | else |
793 | path_put(&nd->path); |
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); |
1045 |
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