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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/quotaops.h> | |
11 | #include <linux/fsnotify.h> | |
12 | #include <linux/module.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/tty.h> | |
15 | #include <linux/namei.h> | |
16 | #include <linux/backing-dev.h> | |
17 | #include <linux/capability.h> | |
18 | #include <linux/security.h> | |
19 | #include <linux/mount.h> | |
20 | #include <linux/vfs.h> | |
21 | #include <linux/fcntl.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 | ||
31 | int vfs_statfs(struct dentry *dentry, struct kstatfs *buf) | |
32 | { | |
33 | int retval = -ENODEV; | |
34 | ||
35 | if (dentry) { | |
36 | retval = -ENOSYS; | |
37 | if (dentry->d_sb->s_op->statfs) { | |
38 | memset(buf, 0, sizeof(*buf)); | |
39 | retval = security_sb_statfs(dentry); | |
40 | if (retval) | |
41 | return retval; | |
42 | retval = dentry->d_sb->s_op->statfs(dentry, buf); | |
43 | if (retval == 0 && buf->f_frsize == 0) | |
44 | buf->f_frsize = buf->f_bsize; | |
45 | } | |
46 | } | |
47 | return retval; | |
48 | } | |
49 | ||
50 | EXPORT_SYMBOL(vfs_statfs); | |
51 | ||
52 | static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf) | |
53 | { | |
54 | struct kstatfs st; | |
55 | int retval; | |
56 | ||
57 | retval = vfs_statfs(dentry, &st); | |
58 | if (retval) | |
59 | return retval; | |
60 | ||
61 | if (sizeof(*buf) == sizeof(st)) | |
62 | memcpy(buf, &st, sizeof(st)); | |
63 | else { | |
64 | if (sizeof buf->f_blocks == 4) { | |
65 | if ((st.f_blocks | st.f_bfree | st.f_bavail) & | |
66 | 0xffffffff00000000ULL) | |
67 | return -EOVERFLOW; | |
68 | /* | |
69 | * f_files and f_ffree may be -1; it's okay to stuff | |
70 | * that into 32 bits | |
71 | */ | |
72 | if (st.f_files != -1 && | |
73 | (st.f_files & 0xffffffff00000000ULL)) | |
74 | return -EOVERFLOW; | |
75 | if (st.f_ffree != -1 && | |
76 | (st.f_ffree & 0xffffffff00000000ULL)) | |
77 | return -EOVERFLOW; | |
78 | } | |
79 | ||
80 | buf->f_type = st.f_type; | |
81 | buf->f_bsize = st.f_bsize; | |
82 | buf->f_blocks = st.f_blocks; | |
83 | buf->f_bfree = st.f_bfree; | |
84 | buf->f_bavail = st.f_bavail; | |
85 | buf->f_files = st.f_files; | |
86 | buf->f_ffree = st.f_ffree; | |
87 | buf->f_fsid = st.f_fsid; | |
88 | buf->f_namelen = st.f_namelen; | |
89 | buf->f_frsize = st.f_frsize; | |
90 | memset(buf->f_spare, 0, sizeof(buf->f_spare)); | |
91 | } | |
92 | return 0; | |
93 | } | |
94 | ||
95 | static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf) | |
96 | { | |
97 | struct kstatfs st; | |
98 | int retval; | |
99 | ||
100 | retval = vfs_statfs(dentry, &st); | |
101 | if (retval) | |
102 | return retval; | |
103 | ||
104 | if (sizeof(*buf) == sizeof(st)) | |
105 | memcpy(buf, &st, sizeof(st)); | |
106 | else { | |
107 | buf->f_type = st.f_type; | |
108 | buf->f_bsize = st.f_bsize; | |
109 | buf->f_blocks = st.f_blocks; | |
110 | buf->f_bfree = st.f_bfree; | |
111 | buf->f_bavail = st.f_bavail; | |
112 | buf->f_files = st.f_files; | |
113 | buf->f_ffree = st.f_ffree; | |
114 | buf->f_fsid = st.f_fsid; | |
115 | buf->f_namelen = st.f_namelen; | |
116 | buf->f_frsize = st.f_frsize; | |
117 | memset(buf->f_spare, 0, sizeof(buf->f_spare)); | |
118 | } | |
119 | return 0; | |
120 | } | |
121 | ||
122 | asmlinkage long sys_statfs(const char __user * path, struct statfs __user * buf) | |
123 | { | |
124 | struct nameidata nd; | |
125 | int error; | |
126 | ||
127 | error = user_path_walk(path, &nd); | |
128 | if (!error) { | |
129 | struct statfs tmp; | |
130 | error = vfs_statfs_native(nd.path.dentry, &tmp); | |
131 | if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) | |
132 | error = -EFAULT; | |
133 | path_put(&nd.path); | |
134 | } | |
135 | return error; | |
136 | } | |
137 | ||
138 | ||
139 | asmlinkage long sys_statfs64(const char __user *path, size_t sz, struct statfs64 __user *buf) | |
140 | { | |
141 | struct nameidata nd; | |
142 | long error; | |
143 | ||
144 | if (sz != sizeof(*buf)) | |
145 | return -EINVAL; | |
146 | error = user_path_walk(path, &nd); | |
147 | if (!error) { | |
148 | struct statfs64 tmp; | |
149 | error = vfs_statfs64(nd.path.dentry, &tmp); | |
150 | if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) | |
151 | error = -EFAULT; | |
152 | path_put(&nd.path); | |
153 | } | |
154 | return error; | |
155 | } | |
156 | ||
157 | ||
158 | asmlinkage long sys_fstatfs(unsigned int fd, struct statfs __user * buf) | |
159 | { | |
160 | struct file * file; | |
161 | struct statfs tmp; | |
162 | int error; | |
163 | ||
164 | error = -EBADF; | |
165 | file = fget(fd); | |
166 | if (!file) | |
167 | goto out; | |
168 | error = vfs_statfs_native(file->f_path.dentry, &tmp); | |
169 | if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) | |
170 | error = -EFAULT; | |
171 | fput(file); | |
172 | out: | |
173 | return error; | |
174 | } | |
175 | ||
176 | asmlinkage long sys_fstatfs64(unsigned int fd, size_t sz, struct statfs64 __user *buf) | |
177 | { | |
178 | struct file * file; | |
179 | struct statfs64 tmp; | |
180 | int error; | |
181 | ||
182 | if (sz != sizeof(*buf)) | |
183 | return -EINVAL; | |
184 | ||
185 | error = -EBADF; | |
186 | file = fget(fd); | |
187 | if (!file) | |
188 | goto out; | |
189 | error = vfs_statfs64(file->f_path.dentry, &tmp); | |
190 | if (!error && copy_to_user(buf, &tmp, sizeof(tmp))) | |
191 | error = -EFAULT; | |
192 | fput(file); | |
193 | out: | |
194 | return error; | |
195 | } | |
196 | ||
197 | int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, | |
198 | struct file *filp) | |
199 | { | |
200 | int err; | |
201 | struct iattr newattrs; | |
202 | ||
203 | /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */ | |
204 | if (length < 0) | |
205 | return -EINVAL; | |
206 | ||
207 | newattrs.ia_size = length; | |
208 | newattrs.ia_valid = ATTR_SIZE | time_attrs; | |
209 | if (filp) { | |
210 | newattrs.ia_file = filp; | |
211 | newattrs.ia_valid |= ATTR_FILE; | |
212 | } | |
213 | ||
214 | /* Remove suid/sgid on truncate too */ | |
215 | newattrs.ia_valid |= should_remove_suid(dentry); | |
216 | ||
217 | mutex_lock(&dentry->d_inode->i_mutex); | |
218 | err = notify_change(dentry, &newattrs); | |
219 | mutex_unlock(&dentry->d_inode->i_mutex); | |
220 | return err; | |
221 | } | |
222 | ||
223 | static long do_sys_truncate(const char __user * path, loff_t length) | |
224 | { | |
225 | struct nameidata nd; | |
226 | struct inode * inode; | |
227 | int error; | |
228 | ||
229 | error = -EINVAL; | |
230 | if (length < 0) /* sorry, but loff_t says... */ | |
231 | goto out; | |
232 | ||
233 | error = user_path_walk(path, &nd); | |
234 | if (error) | |
235 | goto out; | |
236 | inode = nd.path.dentry->d_inode; | |
237 | ||
238 | /* For directories it's -EISDIR, for other non-regulars - -EINVAL */ | |
239 | error = -EISDIR; | |
240 | if (S_ISDIR(inode->i_mode)) | |
241 | goto dput_and_out; | |
242 | ||
243 | error = -EINVAL; | |
244 | if (!S_ISREG(inode->i_mode)) | |
245 | goto dput_and_out; | |
246 | ||
247 | error = mnt_want_write(nd.path.mnt); | |
248 | if (error) | |
249 | goto dput_and_out; | |
250 | ||
251 | error = vfs_permission(&nd, MAY_WRITE); | |
252 | if (error) | |
253 | goto mnt_drop_write_and_out; | |
254 | ||
255 | error = -EPERM; | |
256 | if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) | |
257 | goto mnt_drop_write_and_out; | |
258 | ||
259 | error = get_write_access(inode); | |
260 | if (error) | |
261 | goto mnt_drop_write_and_out; | |
262 | ||
263 | /* | |
264 | * Make sure that there are no leases. get_write_access() protects | |
265 | * against the truncate racing with a lease-granting setlease(). | |
266 | */ | |
267 | error = break_lease(inode, FMODE_WRITE); | |
268 | if (error) | |
269 | goto put_write_and_out; | |
270 | ||
271 | error = locks_verify_truncate(inode, NULL, length); | |
272 | if (!error) { | |
273 | DQUOT_INIT(inode); | |
274 | error = do_truncate(nd.path.dentry, length, 0, NULL); | |
275 | } | |
276 | ||
277 | put_write_and_out: | |
278 | put_write_access(inode); | |
279 | mnt_drop_write_and_out: | |
280 | mnt_drop_write(nd.path.mnt); | |
281 | dput_and_out: | |
282 | path_put(&nd.path); | |
283 | out: | |
284 | return error; | |
285 | } | |
286 | ||
287 | asmlinkage long sys_truncate(const char __user * path, unsigned long length) | |
288 | { | |
289 | /* on 32-bit boxen it will cut the range 2^31--2^32-1 off */ | |
290 | return do_sys_truncate(path, (long)length); | |
291 | } | |
292 | ||
293 | static long do_sys_ftruncate(unsigned int fd, loff_t length, int small) | |
294 | { | |
295 | struct inode * inode; | |
296 | struct dentry *dentry; | |
297 | struct file * file; | |
298 | int error; | |
299 | ||
300 | error = -EINVAL; | |
301 | if (length < 0) | |
302 | goto out; | |
303 | error = -EBADF; | |
304 | file = fget(fd); | |
305 | if (!file) | |
306 | goto out; | |
307 | ||
308 | /* explicitly opened as large or we are on 64-bit box */ | |
309 | if (file->f_flags & O_LARGEFILE) | |
310 | small = 0; | |
311 | ||
312 | dentry = file->f_path.dentry; | |
313 | inode = dentry->d_inode; | |
314 | error = -EINVAL; | |
315 | if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE)) | |
316 | goto out_putf; | |
317 | ||
318 | error = -EINVAL; | |
319 | /* Cannot ftruncate over 2^31 bytes without large file support */ | |
320 | if (small && length > MAX_NON_LFS) | |
321 | goto out_putf; | |
322 | ||
323 | error = -EPERM; | |
324 | if (IS_APPEND(inode)) | |
325 | goto out_putf; | |
326 | ||
327 | error = locks_verify_truncate(inode, file, length); | |
328 | if (!error) | |
329 | error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file); | |
330 | out_putf: | |
331 | fput(file); | |
332 | out: | |
333 | return error; | |
334 | } | |
335 | ||
336 | asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length) | |
337 | { | |
338 | long ret = do_sys_ftruncate(fd, length, 1); | |
339 | /* avoid REGPARM breakage on x86: */ | |
340 | asmlinkage_protect(2, ret, fd, length); | |
341 | return ret; | |
342 | } | |
343 | ||
344 | /* LFS versions of truncate are only needed on 32 bit machines */ | |
345 | #if BITS_PER_LONG == 32 | |
346 | asmlinkage long sys_truncate64(const char __user * path, loff_t length) | |
347 | { | |
348 | return do_sys_truncate(path, length); | |
349 | } | |
350 | ||
351 | asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length) | |
352 | { | |
353 | long ret = do_sys_ftruncate(fd, length, 0); | |
354 | /* avoid REGPARM breakage on x86: */ | |
355 | asmlinkage_protect(2, ret, fd, length); | |
356 | return ret; | |
357 | } | |
358 | #endif | |
359 | ||
360 | asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len) | |
361 | { | |
362 | struct file *file; | |
363 | struct inode *inode; | |
364 | long ret = -EINVAL; | |
365 | ||
366 | if (offset < 0 || len <= 0) | |
367 | goto out; | |
368 | ||
369 | /* Return error if mode is not supported */ | |
370 | ret = -EOPNOTSUPP; | |
371 | if (mode && !(mode & FALLOC_FL_KEEP_SIZE)) | |
372 | goto out; | |
373 | ||
374 | ret = -EBADF; | |
375 | file = fget(fd); | |
376 | if (!file) | |
377 | goto out; | |
378 | if (!(file->f_mode & FMODE_WRITE)) | |
379 | goto out_fput; | |
380 | /* | |
381 | * Revalidate the write permissions, in case security policy has | |
382 | * changed since the files were opened. | |
383 | */ | |
384 | ret = security_file_permission(file, MAY_WRITE); | |
385 | if (ret) | |
386 | goto out_fput; | |
387 | ||
388 | inode = file->f_path.dentry->d_inode; | |
389 | ||
390 | ret = -ESPIPE; | |
391 | if (S_ISFIFO(inode->i_mode)) | |
392 | goto out_fput; | |
393 | ||
394 | ret = -ENODEV; | |
395 | /* | |
396 | * Let individual file system decide if it supports preallocation | |
397 | * for directories or not. | |
398 | */ | |
399 | if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) | |
400 | goto out_fput; | |
401 | ||
402 | ret = -EFBIG; | |
403 | /* Check for wrap through zero too */ | |
404 | if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0)) | |
405 | goto out_fput; | |
406 | ||
407 | if (inode->i_op && inode->i_op->fallocate) | |
408 | ret = inode->i_op->fallocate(inode, mode, offset, len); | |
409 | else | |
410 | ret = -EOPNOTSUPP; | |
411 | ||
412 | out_fput: | |
413 | fput(file); | |
414 | out: | |
415 | return ret; | |
416 | } | |
417 | ||
418 | /* | |
419 | * access() needs to use the real uid/gid, not the effective uid/gid. | |
420 | * We do this by temporarily clearing all FS-related capabilities and | |
421 | * switching the fsuid/fsgid around to the real ones. | |
422 | */ | |
423 | asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode) | |
424 | { | |
425 | struct nameidata nd; | |
426 | int old_fsuid, old_fsgid; | |
427 | kernel_cap_t old_cap; | |
428 | int res; | |
429 | ||
430 | if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */ | |
431 | return -EINVAL; | |
432 | ||
433 | old_fsuid = current->fsuid; | |
434 | old_fsgid = current->fsgid; | |
435 | old_cap = current->cap_effective; | |
436 | ||
437 | current->fsuid = current->uid; | |
438 | current->fsgid = current->gid; | |
439 | ||
440 | /* | |
441 | * Clear the capabilities if we switch to a non-root user | |
442 | * | |
443 | * FIXME: There is a race here against sys_capset. The | |
444 | * capabilities can change yet we will restore the old | |
445 | * value below. We should hold task_capabilities_lock, | |
446 | * but we cannot because user_path_walk can sleep. | |
447 | */ | |
448 | if (current->uid) | |
449 | cap_clear(current->cap_effective); | |
450 | else | |
451 | current->cap_effective = current->cap_permitted; | |
452 | ||
453 | res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd); | |
454 | if (res) | |
455 | goto out; | |
456 | ||
457 | res = vfs_permission(&nd, mode); | |
458 | /* SuS v2 requires we report a read only fs too */ | |
459 | if(res || !(mode & S_IWOTH) || | |
460 | special_file(nd.path.dentry->d_inode->i_mode)) | |
461 | goto out_path_release; | |
462 | /* | |
463 | * This is a rare case where using __mnt_is_readonly() | |
464 | * is OK without a mnt_want/drop_write() pair. Since | |
465 | * no actual write to the fs is performed here, we do | |
466 | * not need to telegraph to that to anyone. | |
467 | * | |
468 | * By doing this, we accept that this access is | |
469 | * inherently racy and know that the fs may change | |
470 | * state before we even see this result. | |
471 | */ | |
472 | if (__mnt_is_readonly(nd.path.mnt)) | |
473 | res = -EROFS; | |
474 | ||
475 | out_path_release: | |
476 | path_put(&nd.path); | |
477 | out: | |
478 | current->fsuid = old_fsuid; | |
479 | current->fsgid = old_fsgid; | |
480 | current->cap_effective = old_cap; | |
481 | ||
482 | return res; | |
483 | } | |
484 | ||
485 | asmlinkage long sys_access(const char __user *filename, int mode) | |
486 | { | |
487 | return sys_faccessat(AT_FDCWD, filename, mode); | |
488 | } | |
489 | ||
490 | asmlinkage long sys_chdir(const char __user * filename) | |
491 | { | |
492 | struct nameidata nd; | |
493 | int error; | |
494 | ||
495 | error = __user_walk(filename, | |
496 | LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd); | |
497 | if (error) | |
498 | goto out; | |
499 | ||
500 | error = vfs_permission(&nd, MAY_EXEC); | |
501 | if (error) | |
502 | goto dput_and_out; | |
503 | ||
504 | set_fs_pwd(current->fs, &nd.path); | |
505 | ||
506 | dput_and_out: | |
507 | path_put(&nd.path); | |
508 | out: | |
509 | return error; | |
510 | } | |
511 | ||
512 | asmlinkage long sys_fchdir(unsigned int fd) | |
513 | { | |
514 | struct file *file; | |
515 | struct inode *inode; | |
516 | int error; | |
517 | ||
518 | error = -EBADF; | |
519 | file = fget(fd); | |
520 | if (!file) | |
521 | goto out; | |
522 | ||
523 | inode = file->f_path.dentry->d_inode; | |
524 | ||
525 | error = -ENOTDIR; | |
526 | if (!S_ISDIR(inode->i_mode)) | |
527 | goto out_putf; | |
528 | ||
529 | error = file_permission(file, MAY_EXEC); | |
530 | if (!error) | |
531 | set_fs_pwd(current->fs, &file->f_path); | |
532 | out_putf: | |
533 | fput(file); | |
534 | out: | |
535 | return error; | |
536 | } | |
537 | ||
538 | asmlinkage long sys_chroot(const char __user * filename) | |
539 | { | |
540 | struct nameidata nd; | |
541 | int error; | |
542 | ||
543 | error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd); | |
544 | if (error) | |
545 | goto out; | |
546 | ||
547 | error = vfs_permission(&nd, MAY_EXEC); | |
548 | if (error) | |
549 | goto dput_and_out; | |
550 | ||
551 | error = -EPERM; | |
552 | if (!capable(CAP_SYS_CHROOT)) | |
553 | goto dput_and_out; | |
554 | ||
555 | set_fs_root(current->fs, &nd.path); | |
556 | set_fs_altroot(); | |
557 | error = 0; | |
558 | dput_and_out: | |
559 | path_put(&nd.path); | |
560 | out: | |
561 | return error; | |
562 | } | |
563 | ||
564 | asmlinkage long sys_fchmod(unsigned int fd, mode_t mode) | |
565 | { | |
566 | struct inode * inode; | |
567 | struct dentry * dentry; | |
568 | struct file * file; | |
569 | int err = -EBADF; | |
570 | struct iattr newattrs; | |
571 | ||
572 | file = fget(fd); | |
573 | if (!file) | |
574 | goto out; | |
575 | ||
576 | dentry = file->f_path.dentry; | |
577 | inode = dentry->d_inode; | |
578 | ||
579 | audit_inode(NULL, dentry); | |
580 | ||
581 | err = mnt_want_write(file->f_path.mnt); | |
582 | if (err) | |
583 | goto out_putf; | |
584 | err = -EPERM; | |
585 | if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) | |
586 | goto out_drop_write; | |
587 | mutex_lock(&inode->i_mutex); | |
588 | if (mode == (mode_t) -1) | |
589 | mode = inode->i_mode; | |
590 | newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); | |
591 | newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; | |
592 | err = notify_change(dentry, &newattrs); | |
593 | mutex_unlock(&inode->i_mutex); | |
594 | ||
595 | out_drop_write: | |
596 | mnt_drop_write(file->f_path.mnt); | |
597 | out_putf: | |
598 | fput(file); | |
599 | out: | |
600 | return err; | |
601 | } | |
602 | ||
603 | asmlinkage long sys_fchmodat(int dfd, const char __user *filename, | |
604 | mode_t mode) | |
605 | { | |
606 | struct nameidata nd; | |
607 | struct inode * inode; | |
608 | int error; | |
609 | struct iattr newattrs; | |
610 | ||
611 | error = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd); | |
612 | if (error) | |
613 | goto out; | |
614 | inode = nd.path.dentry->d_inode; | |
615 | ||
616 | error = mnt_want_write(nd.path.mnt); | |
617 | if (error) | |
618 | goto dput_and_out; | |
619 | ||
620 | error = -EPERM; | |
621 | if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) | |
622 | goto out_drop_write; | |
623 | ||
624 | mutex_lock(&inode->i_mutex); | |
625 | if (mode == (mode_t) -1) | |
626 | mode = inode->i_mode; | |
627 | newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO); | |
628 | newattrs.ia_valid = ATTR_MODE | ATTR_CTIME; | |
629 | error = notify_change(nd.path.dentry, &newattrs); | |
630 | mutex_unlock(&inode->i_mutex); | |
631 | ||
632 | out_drop_write: | |
633 | mnt_drop_write(nd.path.mnt); | |
634 | dput_and_out: | |
635 | path_put(&nd.path); | |
636 | out: | |
637 | return error; | |
638 | } | |
639 | ||
640 | asmlinkage long sys_chmod(const char __user *filename, mode_t mode) | |
641 | { | |
642 | return sys_fchmodat(AT_FDCWD, filename, mode); | |
643 | } | |
644 | ||
645 | static int chown_common(struct dentry * dentry, uid_t user, gid_t group) | |
646 | { | |
647 | struct inode * inode; | |
648 | int error; | |
649 | struct iattr newattrs; | |
650 | ||
651 | error = -ENOENT; | |
652 | if (!(inode = dentry->d_inode)) { | |
653 | printk(KERN_ERR "chown_common: NULL inode\n"); | |
654 | goto out; | |
655 | } | |
656 | error = -EPERM; | |
657 | if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) | |
658 | goto out; | |
659 | newattrs.ia_valid = ATTR_CTIME; | |
660 | if (user != (uid_t) -1) { | |
661 | newattrs.ia_valid |= ATTR_UID; | |
662 | newattrs.ia_uid = user; | |
663 | } | |
664 | if (group != (gid_t) -1) { | |
665 | newattrs.ia_valid |= ATTR_GID; | |
666 | newattrs.ia_gid = group; | |
667 | } | |
668 | if (!S_ISDIR(inode->i_mode)) | |
669 | newattrs.ia_valid |= | |
670 | ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV; | |
671 | mutex_lock(&inode->i_mutex); | |
672 | error = notify_change(dentry, &newattrs); | |
673 | mutex_unlock(&inode->i_mutex); | |
674 | out: | |
675 | return error; | |
676 | } | |
677 | ||
678 | asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group) | |
679 | { | |
680 | struct nameidata nd; | |
681 | int error; | |
682 | ||
683 | error = user_path_walk(filename, &nd); | |
684 | if (error) | |
685 | goto out; | |
686 | error = mnt_want_write(nd.path.mnt); | |
687 | if (error) | |
688 | goto out_release; | |
689 | error = chown_common(nd.path.dentry, user, group); | |
690 | mnt_drop_write(nd.path.mnt); | |
691 | out_release: | |
692 | path_put(&nd.path); | |
693 | out: | |
694 | return error; | |
695 | } | |
696 | ||
697 | asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user, | |
698 | gid_t group, int flag) | |
699 | { | |
700 | struct nameidata nd; | |
701 | int error = -EINVAL; | |
702 | int follow; | |
703 | ||
704 | if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0) | |
705 | goto out; | |
706 | ||
707 | follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW; | |
708 | error = __user_walk_fd(dfd, filename, follow, &nd); | |
709 | if (error) | |
710 | goto out; | |
711 | error = mnt_want_write(nd.path.mnt); | |
712 | if (error) | |
713 | goto out_release; | |
714 | error = chown_common(nd.path.dentry, user, group); | |
715 | mnt_drop_write(nd.path.mnt); | |
716 | out_release: | |
717 | path_put(&nd.path); | |
718 | out: | |
719 | return error; | |
720 | } | |
721 | ||
722 | asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group) | |
723 | { | |
724 | struct nameidata nd; | |
725 | int error; | |
726 | ||
727 | error = user_path_walk_link(filename, &nd); | |
728 | if (error) | |
729 | goto out; | |
730 | error = mnt_want_write(nd.path.mnt); | |
731 | if (error) | |
732 | goto out_release; | |
733 | error = chown_common(nd.path.dentry, user, group); | |
734 | mnt_drop_write(nd.path.mnt); | |
735 | out_release: | |
736 | path_put(&nd.path); | |
737 | out: | |
738 | return error; | |
739 | } | |
740 | ||
741 | ||
742 | asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group) | |
743 | { | |
744 | struct file * file; | |
745 | int error = -EBADF; | |
746 | struct dentry * dentry; | |
747 | ||
748 | file = fget(fd); | |
749 | if (!file) | |
750 | goto out; | |
751 | ||
752 | error = mnt_want_write(file->f_path.mnt); | |
753 | if (error) | |
754 | goto out_fput; | |
755 | dentry = file->f_path.dentry; | |
756 | audit_inode(NULL, dentry); | |
757 | error = chown_common(dentry, user, group); | |
758 | mnt_drop_write(file->f_path.mnt); | |
759 | out_fput: | |
760 | fput(file); | |
761 | out: | |
762 | return error; | |
763 | } | |
764 | ||
765 | /* | |
766 | * You have to be very careful that these write | |
767 | * counts get cleaned up in error cases and | |
768 | * upon __fput(). This should probably never | |
769 | * be called outside of __dentry_open(). | |
770 | */ | |
771 | static inline int __get_file_write_access(struct inode *inode, | |
772 | struct vfsmount *mnt) | |
773 | { | |
774 | int error; | |
775 | error = get_write_access(inode); | |
776 | if (error) | |
777 | return error; | |
778 | /* | |
779 | * Do not take mount writer counts on | |
780 | * special files since no writes to | |
781 | * the mount itself will occur. | |
782 | */ | |
783 | if (!special_file(inode->i_mode)) { | |
784 | /* | |
785 | * Balanced in __fput() | |
786 | */ | |
787 | error = mnt_want_write(mnt); | |
788 | if (error) | |
789 | put_write_access(inode); | |
790 | } | |
791 | return error; | |
792 | } | |
793 | ||
794 | static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt, | |
795 | int flags, struct file *f, | |
796 | int (*open)(struct inode *, struct file *)) | |
797 | { | |
798 | struct inode *inode; | |
799 | int error; | |
800 | ||
801 | f->f_flags = flags; | |
802 | f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK | | |
803 | FMODE_PREAD | FMODE_PWRITE; | |
804 | inode = dentry->d_inode; | |
805 | if (f->f_mode & FMODE_WRITE) { | |
806 | error = __get_file_write_access(inode, mnt); | |
807 | if (error) | |
808 | goto cleanup_file; | |
809 | } | |
810 | ||
811 | f->f_mapping = inode->i_mapping; | |
812 | f->f_path.dentry = dentry; | |
813 | f->f_path.mnt = mnt; | |
814 | f->f_pos = 0; | |
815 | f->f_op = fops_get(inode->i_fop); | |
816 | file_move(f, &inode->i_sb->s_files); | |
817 | ||
818 | error = security_dentry_open(f); | |
819 | if (error) | |
820 | goto cleanup_all; | |
821 | ||
822 | if (!open && f->f_op) | |
823 | open = f->f_op->open; | |
824 | if (open) { | |
825 | error = open(inode, f); | |
826 | if (error) | |
827 | goto cleanup_all; | |
828 | } | |
829 | ||
830 | f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC); | |
831 | ||
832 | file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping); | |
833 | ||
834 | /* NB: we're sure to have correct a_ops only after f_op->open */ | |
835 | if (f->f_flags & O_DIRECT) { | |
836 | if (!f->f_mapping->a_ops || | |
837 | ((!f->f_mapping->a_ops->direct_IO) && | |
838 | (!f->f_mapping->a_ops->get_xip_page))) { | |
839 | fput(f); | |
840 | f = ERR_PTR(-EINVAL); | |
841 | } | |
842 | } | |
843 | ||
844 | return f; | |
845 | ||
846 | cleanup_all: | |
847 | fops_put(f->f_op); | |
848 | if (f->f_mode & FMODE_WRITE) { | |
849 | put_write_access(inode); | |
850 | if (!special_file(inode->i_mode)) | |
851 | mnt_drop_write(mnt); | |
852 | } | |
853 | file_kill(f); | |
854 | f->f_path.dentry = NULL; | |
855 | f->f_path.mnt = NULL; | |
856 | cleanup_file: | |
857 | put_filp(f); | |
858 | dput(dentry); | |
859 | mntput(mnt); | |
860 | return ERR_PTR(error); | |
861 | } | |
862 | ||
863 | /** | |
864 | * lookup_instantiate_filp - instantiates the open intent filp | |
865 | * @nd: pointer to nameidata | |
866 | * @dentry: pointer to dentry | |
867 | * @open: open callback | |
868 | * | |
869 | * Helper for filesystems that want to use lookup open intents and pass back | |
870 | * a fully instantiated struct file to the caller. | |
871 | * This function is meant to be called from within a filesystem's | |
872 | * lookup method. | |
873 | * Beware of calling it for non-regular files! Those ->open methods might block | |
874 | * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo, | |
875 | * leading to a deadlock, as nobody can open that fifo anymore, because | |
876 | * another process to open fifo will block on locked parent when doing lookup). | |
877 | * Note that in case of error, nd->intent.open.file is destroyed, but the | |
878 | * path information remains valid. | |
879 | * If the open callback is set to NULL, then the standard f_op->open() | |
880 | * filesystem callback is substituted. | |
881 | */ | |
882 | struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry, | |
883 | int (*open)(struct inode *, struct file *)) | |
884 | { | |
885 | if (IS_ERR(nd->intent.open.file)) | |
886 | goto out; | |
887 | if (IS_ERR(dentry)) | |
888 | goto out_err; | |
889 | nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->path.mnt), | |
890 | nd->intent.open.flags - 1, | |
891 | nd->intent.open.file, | |
892 | open); | |
893 | out: | |
894 | return nd->intent.open.file; | |
895 | out_err: | |
896 | release_open_intent(nd); | |
897 | nd->intent.open.file = (struct file *)dentry; | |
898 | goto out; | |
899 | } | |
900 | EXPORT_SYMBOL_GPL(lookup_instantiate_filp); | |
901 | ||
902 | /** | |
903 | * nameidata_to_filp - convert a nameidata to an open filp. | |
904 | * @nd: pointer to nameidata | |
905 | * @flags: open flags | |
906 | * | |
907 | * Note that this function destroys the original nameidata | |
908 | */ | |
909 | struct file *nameidata_to_filp(struct nameidata *nd, int flags) | |
910 | { | |
911 | struct file *filp; | |
912 | ||
913 | /* Pick up the filp from the open intent */ | |
914 | filp = nd->intent.open.file; | |
915 | /* Has the filesystem initialised the file for us? */ | |
916 | if (filp->f_path.dentry == NULL) | |
917 | filp = __dentry_open(nd->path.dentry, nd->path.mnt, flags, filp, | |
918 | NULL); | |
919 | else | |
920 | path_put(&nd->path); | |
921 | return filp; | |
922 | } | |
923 | ||
924 | /* | |
925 | * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an | |
926 | * error. | |
927 | */ | |
928 | struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags) | |
929 | { | |
930 | int error; | |
931 | struct file *f; | |
932 | ||
933 | /* | |
934 | * We must always pass in a valid mount pointer. Historically | |
935 | * callers got away with not passing it, but we must enforce this at | |
936 | * the earliest possible point now to avoid strange problems deep in the | |
937 | * filesystem stack. | |
938 | */ | |
939 | if (!mnt) { | |
940 | printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__); | |
941 | dump_stack(); | |
942 | return ERR_PTR(-EINVAL); | |
943 | } | |
944 | ||
945 | error = -ENFILE; | |
946 | f = get_empty_filp(); | |
947 | if (f == NULL) { | |
948 | dput(dentry); | |
949 | mntput(mnt); | |
950 | return ERR_PTR(error); | |
951 | } | |
952 | ||
953 | return __dentry_open(dentry, mnt, flags, f, NULL); | |
954 | } | |
955 | EXPORT_SYMBOL(dentry_open); | |
956 | ||
957 | /* | |
958 | * Find an empty file descriptor entry, and mark it busy. | |
959 | */ | |
960 | int get_unused_fd_flags(int flags) | |
961 | { | |
962 | struct files_struct * files = current->files; | |
963 | int fd, error; | |
964 | struct fdtable *fdt; | |
965 | ||
966 | error = -EMFILE; | |
967 | spin_lock(&files->file_lock); | |
968 | ||
969 | repeat: | |
970 | fdt = files_fdtable(files); | |
971 | fd = find_next_zero_bit(fdt->open_fds->fds_bits, fdt->max_fds, | |
972 | files->next_fd); | |
973 | ||
974 | /* | |
975 | * N.B. For clone tasks sharing a files structure, this test | |
976 | * will limit the total number of files that can be opened. | |
977 | */ | |
978 | if (fd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur) | |
979 | goto out; | |
980 | ||
981 | /* Do we need to expand the fd array or fd set? */ | |
982 | error = expand_files(files, fd); | |
983 | if (error < 0) | |
984 | goto out; | |
985 | ||
986 | if (error) { | |
987 | /* | |
988 | * If we needed to expand the fs array we | |
989 | * might have blocked - try again. | |
990 | */ | |
991 | error = -EMFILE; | |
992 | goto repeat; | |
993 | } | |
994 | ||
995 | FD_SET(fd, fdt->open_fds); | |
996 | if (flags & O_CLOEXEC) | |
997 | FD_SET(fd, fdt->close_on_exec); | |
998 | else | |
999 | FD_CLR(fd, fdt->close_on_exec); | |
1000 | files->next_fd = fd + 1; | |
1001 | #if 1 | |
1002 | /* Sanity check */ | |
1003 | if (fdt->fd[fd] != NULL) { | |
1004 | printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd); | |
1005 | fdt->fd[fd] = NULL; | |
1006 | } | |
1007 | #endif | |
1008 | error = fd; | |
1009 | ||
1010 | out: | |
1011 | spin_unlock(&files->file_lock); | |
1012 | return error; | |
1013 | } | |
1014 | ||
1015 | int get_unused_fd(void) | |
1016 | { | |
1017 | return get_unused_fd_flags(0); | |
1018 | } | |
1019 | ||
1020 | EXPORT_SYMBOL(get_unused_fd); | |
1021 | ||
1022 | static void __put_unused_fd(struct files_struct *files, unsigned int fd) | |
1023 | { | |
1024 | struct fdtable *fdt = files_fdtable(files); | |
1025 | __FD_CLR(fd, fdt->open_fds); | |
1026 | if (fd < files->next_fd) | |
1027 | files->next_fd = fd; | |
1028 | } | |
1029 | ||
1030 | void put_unused_fd(unsigned int fd) | |
1031 | { | |
1032 | struct files_struct *files = current->files; | |
1033 | spin_lock(&files->file_lock); | |
1034 | __put_unused_fd(files, fd); | |
1035 | spin_unlock(&files->file_lock); | |
1036 | } | |
1037 | ||
1038 | EXPORT_SYMBOL(put_unused_fd); | |
1039 | ||
1040 | /* | |
1041 | * Install a file pointer in the fd array. | |
1042 | * | |
1043 | * The VFS is full of places where we drop the files lock between | |
1044 | * setting the open_fds bitmap and installing the file in the file | |
1045 | * array. At any such point, we are vulnerable to a dup2() race | |
1046 | * installing a file in the array before us. We need to detect this and | |
1047 | * fput() the struct file we are about to overwrite in this case. | |
1048 | * | |
1049 | * It should never happen - if we allow dup2() do it, _really_ bad things | |
1050 | * will follow. | |
1051 | */ | |
1052 | ||
1053 | void fd_install(unsigned int fd, struct file *file) | |
1054 | { | |
1055 | struct files_struct *files = current->files; | |
1056 | struct fdtable *fdt; | |
1057 | spin_lock(&files->file_lock); | |
1058 | fdt = files_fdtable(files); | |
1059 | BUG_ON(fdt->fd[fd] != NULL); | |
1060 | rcu_assign_pointer(fdt->fd[fd], file); | |
1061 | spin_unlock(&files->file_lock); | |
1062 | } | |
1063 | ||
1064 | EXPORT_SYMBOL(fd_install); | |
1065 | ||
1066 | long do_sys_open(int dfd, const char __user *filename, int flags, int mode) | |
1067 | { | |
1068 | char *tmp = getname(filename); | |
1069 | int fd = PTR_ERR(tmp); | |
1070 | ||
1071 | if (!IS_ERR(tmp)) { | |
1072 | fd = get_unused_fd_flags(flags); | |
1073 | if (fd >= 0) { | |
1074 | struct file *f = do_filp_open(dfd, tmp, flags, mode); | |
1075 | if (IS_ERR(f)) { | |
1076 | put_unused_fd(fd); | |
1077 | fd = PTR_ERR(f); | |
1078 | } else { | |
1079 | fsnotify_open(f->f_path.dentry); | |
1080 | fd_install(fd, f); | |
1081 | } | |
1082 | } | |
1083 | putname(tmp); | |
1084 | } | |
1085 | return fd; | |
1086 | } | |
1087 | ||
1088 | asmlinkage long sys_open(const char __user *filename, int flags, int mode) | |
1089 | { | |
1090 | long ret; | |
1091 | ||
1092 | if (force_o_largefile()) | |
1093 | flags |= O_LARGEFILE; | |
1094 | ||
1095 | ret = do_sys_open(AT_FDCWD, filename, flags, mode); | |
1096 | /* avoid REGPARM breakage on x86: */ | |
1097 | asmlinkage_protect(3, ret, filename, flags, mode); | |
1098 | return ret; | |
1099 | } | |
1100 | ||
1101 | asmlinkage long sys_openat(int dfd, const char __user *filename, int flags, | |
1102 | int mode) | |
1103 | { | |
1104 | long ret; | |
1105 | ||
1106 | if (force_o_largefile()) | |
1107 | flags |= O_LARGEFILE; | |
1108 | ||
1109 | ret = do_sys_open(dfd, filename, flags, mode); | |
1110 | /* avoid REGPARM breakage on x86: */ | |
1111 | asmlinkage_protect(4, ret, dfd, filename, flags, mode); | |
1112 | return ret; | |
1113 | } | |
1114 | ||
1115 | #ifndef __alpha__ | |
1116 | ||
1117 | /* | |
1118 | * For backward compatibility? Maybe this should be moved | |
1119 | * into arch/i386 instead? | |
1120 | */ | |
1121 | asmlinkage long sys_creat(const char __user * pathname, int mode) | |
1122 | { | |
1123 | return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode); | |
1124 | } | |
1125 | ||
1126 | #endif | |
1127 | ||
1128 | /* | |
1129 | * "id" is the POSIX thread ID. We use the | |
1130 | * files pointer for this.. | |
1131 | */ | |
1132 | int filp_close(struct file *filp, fl_owner_t id) | |
1133 | { | |
1134 | int retval = 0; | |
1135 | ||
1136 | if (!file_count(filp)) { | |
1137 | printk(KERN_ERR "VFS: Close: file count is 0\n"); | |
1138 | return 0; | |
1139 | } | |
1140 | ||
1141 | if (filp->f_op && filp->f_op->flush) | |
1142 | retval = filp->f_op->flush(filp, id); | |
1143 | ||
1144 | dnotify_flush(filp, id); | |
1145 | locks_remove_posix(filp, id); | |
1146 | fput(filp); | |
1147 | return retval; | |
1148 | } | |
1149 | ||
1150 | EXPORT_SYMBOL(filp_close); | |
1151 | ||
1152 | /* | |
1153 | * Careful here! We test whether the file pointer is NULL before | |
1154 | * releasing the fd. This ensures that one clone task can't release | |
1155 | * an fd while another clone is opening it. | |
1156 | */ | |
1157 | asmlinkage long sys_close(unsigned int fd) | |
1158 | { | |
1159 | struct file * filp; | |
1160 | struct files_struct *files = current->files; | |
1161 | struct fdtable *fdt; | |
1162 | int retval; | |
1163 | ||
1164 | spin_lock(&files->file_lock); | |
1165 | fdt = files_fdtable(files); | |
1166 | if (fd >= fdt->max_fds) | |
1167 | goto out_unlock; | |
1168 | filp = fdt->fd[fd]; | |
1169 | if (!filp) | |
1170 | goto out_unlock; | |
1171 | rcu_assign_pointer(fdt->fd[fd], NULL); | |
1172 | FD_CLR(fd, fdt->close_on_exec); | |
1173 | __put_unused_fd(files, fd); | |
1174 | spin_unlock(&files->file_lock); | |
1175 | retval = filp_close(filp, files); | |
1176 | ||
1177 | /* can't restart close syscall because file table entry was cleared */ | |
1178 | if (unlikely(retval == -ERESTARTSYS || | |
1179 | retval == -ERESTARTNOINTR || | |
1180 | retval == -ERESTARTNOHAND || | |
1181 | retval == -ERESTART_RESTARTBLOCK)) | |
1182 | retval = -EINTR; | |
1183 | ||
1184 | return retval; | |
1185 | ||
1186 | out_unlock: | |
1187 | spin_unlock(&files->file_lock); | |
1188 | return -EBADF; | |
1189 | } | |
1190 | ||
1191 | EXPORT_SYMBOL(sys_close); | |
1192 | ||
1193 | /* | |
1194 | * This routine simulates a hangup on the tty, to arrange that users | |
1195 | * are given clean terminals at login time. | |
1196 | */ | |
1197 | asmlinkage long sys_vhangup(void) | |
1198 | { | |
1199 | if (capable(CAP_SYS_TTY_CONFIG)) { | |
1200 | /* XXX: this needs locking */ | |
1201 | tty_vhangup(current->signal->tty); | |
1202 | return 0; | |
1203 | } | |
1204 | return -EPERM; | |
1205 | } | |
1206 | ||
1207 | /* | |
1208 | * Called when an inode is about to be open. | |
1209 | * We use this to disallow opening large files on 32bit systems if | |
1210 | * the caller didn't specify O_LARGEFILE. On 64bit systems we force | |
1211 | * on this flag in sys_open. | |
1212 | */ | |
1213 | int generic_file_open(struct inode * inode, struct file * filp) | |
1214 | { | |
1215 | if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS) | |
1216 | return -EOVERFLOW; | |
1217 | return 0; | |
1218 | } | |
1219 | ||
1220 | EXPORT_SYMBOL(generic_file_open); | |
1221 | ||
1222 | /* | |
1223 | * This is used by subsystems that don't want seekable | |
1224 | * file descriptors | |
1225 | */ | |
1226 | int nonseekable_open(struct inode *inode, struct file *filp) | |
1227 | { | |
1228 | filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE); | |
1229 | return 0; | |
1230 | } | |
1231 | ||
1232 | EXPORT_SYMBOL(nonseekable_open); |