1 /*
2 * linux/fs/fat/file.c
3 *
4 * Written 1992,1993 by Werner Almesberger
5 *
6 * regular file handling primitives for fat-based filesystems
7 */
8
9 #include <linux/capability.h>
10 #include <linux/module.h>
11 #include <linux/compat.h>
12 #include <linux/mount.h>
13 #include <linux/time.h>
14 #include <linux/buffer_head.h>
15 #include <linux/writeback.h>
16 #include <linux/backing-dev.h>
17 #include <linux/blkdev.h>
18 #include <linux/fsnotify.h>
19 #include <linux/security.h>
20 #include "fat.h"
21
fat_ioctl_get_attributes(struct inode * inode,u32 __user * user_attr)22 static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
23 {
24 u32 attr;
25
26 mutex_lock(&inode->i_mutex);
27 attr = fat_make_attrs(inode);
28 mutex_unlock(&inode->i_mutex);
29
30 return put_user(attr, user_attr);
31 }
32
fat_ioctl_set_attributes(struct file * file,u32 __user * user_attr)33 static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
34 {
35 struct inode *inode = file->f_path.dentry->d_inode;
36 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
37 int is_dir = S_ISDIR(inode->i_mode);
38 u32 attr, oldattr;
39 struct iattr ia;
40 int err;
41
42 err = get_user(attr, user_attr);
43 if (err)
44 goto out;
45
46 mutex_lock(&inode->i_mutex);
47 err = mnt_want_write_file(file);
48 if (err)
49 goto out_unlock_inode;
50
51 /*
52 * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
53 * prevents the user from turning us into a VFAT
54 * longname entry. Also, we obviously can't set
55 * any of the NTFS attributes in the high 24 bits.
56 */
57 attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);
58 /* Merge in ATTR_VOLUME and ATTR_DIR */
59 attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
60 (is_dir ? ATTR_DIR : 0);
61 oldattr = fat_make_attrs(inode);
62
63 /* Equivalent to a chmod() */
64 ia.ia_valid = ATTR_MODE | ATTR_CTIME;
65 ia.ia_ctime = current_fs_time(inode->i_sb);
66 if (is_dir)
67 ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
68 else {
69 ia.ia_mode = fat_make_mode(sbi, attr,
70 S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));
71 }
72
73 /* The root directory has no attributes */
74 if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
75 err = -EINVAL;
76 goto out_drop_write;
77 }
78
79 if (sbi->options.sys_immutable &&
80 ((attr | oldattr) & ATTR_SYS) &&
81 !capable(CAP_LINUX_IMMUTABLE)) {
82 err = -EPERM;
83 goto out_drop_write;
84 }
85
86 /*
87 * The security check is questionable... We single
88 * out the RO attribute for checking by the security
89 * module, just because it maps to a file mode.
90 */
91 err = security_inode_setattr(file->f_path.dentry, &ia);
92 if (err)
93 goto out_drop_write;
94
95 /* This MUST be done before doing anything irreversible... */
96 err = fat_setattr(file->f_path.dentry, &ia);
97 if (err)
98 goto out_drop_write;
99
100 fsnotify_change(file->f_path.dentry, ia.ia_valid);
101 if (sbi->options.sys_immutable) {
102 if (attr & ATTR_SYS)
103 inode->i_flags |= S_IMMUTABLE;
104 else
105 inode->i_flags &= ~S_IMMUTABLE;
106 }
107
108 fat_save_attrs(inode, attr);
109 mark_inode_dirty(inode);
110 out_drop_write:
111 mnt_drop_write_file(file);
112 out_unlock_inode:
113 mutex_unlock(&inode->i_mutex);
114 out:
115 return err;
116 }
117
fat_generic_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)118 long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
119 {
120 struct inode *inode = filp->f_path.dentry->d_inode;
121 u32 __user *user_attr = (u32 __user *)arg;
122
123 switch (cmd) {
124 case FAT_IOCTL_GET_ATTRIBUTES:
125 return fat_ioctl_get_attributes(inode, user_attr);
126 case FAT_IOCTL_SET_ATTRIBUTES:
127 return fat_ioctl_set_attributes(filp, user_attr);
128 default:
129 return -ENOTTY; /* Inappropriate ioctl for device */
130 }
131 }
132
133 #ifdef CONFIG_COMPAT
fat_generic_compat_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)134 static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd,
135 unsigned long arg)
136
137 {
138 return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
139 }
140 #endif
141
fat_file_release(struct inode * inode,struct file * filp)142 static int fat_file_release(struct inode *inode, struct file *filp)
143 {
144 if ((filp->f_mode & FMODE_WRITE) &&
145 MSDOS_SB(inode->i_sb)->options.flush) {
146 fat_flush_inodes(inode->i_sb, inode, NULL);
147 congestion_wait(BLK_RW_ASYNC, HZ/10);
148 }
149 return 0;
150 }
151
fat_file_fsync(struct file * filp,loff_t start,loff_t end,int datasync)152 int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
153 {
154 struct inode *inode = filp->f_mapping->host;
155 int res, err;
156
157 res = generic_file_fsync(filp, start, end, datasync);
158 err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
159
160 return res ? res : err;
161 }
162
163
164 const struct file_operations fat_file_operations = {
165 .llseek = generic_file_llseek,
166 .read = do_sync_read,
167 .write = do_sync_write,
168 .aio_read = generic_file_aio_read,
169 .aio_write = generic_file_aio_write,
170 .mmap = generic_file_mmap,
171 .release = fat_file_release,
172 .unlocked_ioctl = fat_generic_ioctl,
173 #ifdef CONFIG_COMPAT
174 .compat_ioctl = fat_generic_compat_ioctl,
175 #endif
176 .fsync = fat_file_fsync,
177 .splice_read = generic_file_splice_read,
178 };
179
fat_cont_expand(struct inode * inode,loff_t size)180 static int fat_cont_expand(struct inode *inode, loff_t size)
181 {
182 struct address_space *mapping = inode->i_mapping;
183 loff_t start = inode->i_size, count = size - inode->i_size;
184 int err;
185
186 err = generic_cont_expand_simple(inode, size);
187 if (err)
188 goto out;
189
190 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
191 mark_inode_dirty(inode);
192 if (IS_SYNC(inode)) {
193 int err2;
194
195 /*
196 * Opencode syncing since we don't have a file open to use
197 * standard fsync path.
198 */
199 err = filemap_fdatawrite_range(mapping, start,
200 start + count - 1);
201 err2 = sync_mapping_buffers(mapping);
202 if (!err)
203 err = err2;
204 err2 = write_inode_now(inode, 1);
205 if (!err)
206 err = err2;
207 if (!err) {
208 err = filemap_fdatawait_range(mapping, start,
209 start + count - 1);
210 }
211 }
212 out:
213 return err;
214 }
215
216 /* Free all clusters after the skip'th cluster. */
fat_free(struct inode * inode,int skip)217 static int fat_free(struct inode *inode, int skip)
218 {
219 struct super_block *sb = inode->i_sb;
220 int err, wait, free_start, i_start, i_logstart;
221
222 if (MSDOS_I(inode)->i_start == 0)
223 return 0;
224
225 fat_cache_inval_inode(inode);
226
227 wait = IS_DIRSYNC(inode);
228 i_start = free_start = MSDOS_I(inode)->i_start;
229 i_logstart = MSDOS_I(inode)->i_logstart;
230
231 /* First, we write the new file size. */
232 if (!skip) {
233 MSDOS_I(inode)->i_start = 0;
234 MSDOS_I(inode)->i_logstart = 0;
235 }
236 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
237 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
238 if (wait) {
239 err = fat_sync_inode(inode);
240 if (err) {
241 MSDOS_I(inode)->i_start = i_start;
242 MSDOS_I(inode)->i_logstart = i_logstart;
243 return err;
244 }
245 } else
246 mark_inode_dirty(inode);
247
248 /* Write a new EOF, and get the remaining cluster chain for freeing. */
249 if (skip) {
250 struct fat_entry fatent;
251 int ret, fclus, dclus;
252
253 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
254 if (ret < 0)
255 return ret;
256 else if (ret == FAT_ENT_EOF)
257 return 0;
258
259 fatent_init(&fatent);
260 ret = fat_ent_read(inode, &fatent, dclus);
261 if (ret == FAT_ENT_EOF) {
262 fatent_brelse(&fatent);
263 return 0;
264 } else if (ret == FAT_ENT_FREE) {
265 fat_fs_error(sb,
266 "%s: invalid cluster chain (i_pos %lld)",
267 __func__, MSDOS_I(inode)->i_pos);
268 ret = -EIO;
269 } else if (ret > 0) {
270 err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
271 if (err)
272 ret = err;
273 }
274 fatent_brelse(&fatent);
275 if (ret < 0)
276 return ret;
277
278 free_start = ret;
279 }
280 inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
281
282 /* Freeing the remained cluster chain */
283 return fat_free_clusters(inode, free_start);
284 }
285
fat_truncate_blocks(struct inode * inode,loff_t offset)286 void fat_truncate_blocks(struct inode *inode, loff_t offset)
287 {
288 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
289 const unsigned int cluster_size = sbi->cluster_size;
290 int nr_clusters;
291
292 /*
293 * This protects against truncating a file bigger than it was then
294 * trying to write into the hole.
295 */
296 if (MSDOS_I(inode)->mmu_private > offset)
297 MSDOS_I(inode)->mmu_private = offset;
298
299 nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
300
301 fat_free(inode, nr_clusters);
302 fat_flush_inodes(inode->i_sb, inode, NULL);
303 }
304
fat_getattr(struct vfsmount * mnt,struct dentry * dentry,struct kstat * stat)305 int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
306 {
307 struct inode *inode = dentry->d_inode;
308 generic_fillattr(inode, stat);
309 stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
310 return 0;
311 }
312 EXPORT_SYMBOL_GPL(fat_getattr);
313
fat_sanitize_mode(const struct msdos_sb_info * sbi,struct inode * inode,umode_t * mode_ptr)314 static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
315 struct inode *inode, umode_t *mode_ptr)
316 {
317 umode_t mask, perm;
318
319 /*
320 * Note, the basic check is already done by a caller of
321 * (attr->ia_mode & ~FAT_VALID_MODE)
322 */
323
324 if (S_ISREG(inode->i_mode))
325 mask = sbi->options.fs_fmask;
326 else
327 mask = sbi->options.fs_dmask;
328
329 perm = *mode_ptr & ~(S_IFMT | mask);
330
331 /*
332 * Of the r and x bits, all (subject to umask) must be present. Of the
333 * w bits, either all (subject to umask) or none must be present.
334 *
335 * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
336 */
337 if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
338 return -EPERM;
339 if (fat_mode_can_hold_ro(inode)) {
340 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
341 return -EPERM;
342 } else {
343 if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
344 return -EPERM;
345 }
346
347 *mode_ptr &= S_IFMT | perm;
348
349 return 0;
350 }
351
fat_allow_set_time(struct msdos_sb_info * sbi,struct inode * inode)352 static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
353 {
354 umode_t allow_utime = sbi->options.allow_utime;
355
356 if (current_fsuid() != inode->i_uid) {
357 if (in_group_p(inode->i_gid))
358 allow_utime >>= 3;
359 if (allow_utime & MAY_WRITE)
360 return 1;
361 }
362
363 /* use a default check */
364 return 0;
365 }
366
367 #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
368 /* valid file mode bits */
369 #define FAT_VALID_MODE (S_IFREG | S_IFDIR | S_IRWXUGO)
370
fat_setattr(struct dentry * dentry,struct iattr * attr)371 int fat_setattr(struct dentry *dentry, struct iattr *attr)
372 {
373 struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
374 struct inode *inode = dentry->d_inode;
375 unsigned int ia_valid;
376 int error;
377
378 /* Check for setting the inode time. */
379 ia_valid = attr->ia_valid;
380 if (ia_valid & TIMES_SET_FLAGS) {
381 if (fat_allow_set_time(sbi, inode))
382 attr->ia_valid &= ~TIMES_SET_FLAGS;
383 }
384
385 error = inode_change_ok(inode, attr);
386 attr->ia_valid = ia_valid;
387 if (error) {
388 if (sbi->options.quiet)
389 error = 0;
390 goto out;
391 }
392
393 /*
394 * Expand the file. Since inode_setattr() updates ->i_size
395 * before calling the ->truncate(), but FAT needs to fill the
396 * hole before it. XXX: this is no longer true with new truncate
397 * sequence.
398 */
399 if (attr->ia_valid & ATTR_SIZE) {
400 inode_dio_wait(inode);
401
402 if (attr->ia_size > inode->i_size) {
403 error = fat_cont_expand(inode, attr->ia_size);
404 if (error || attr->ia_valid == ATTR_SIZE)
405 goto out;
406 attr->ia_valid &= ~ATTR_SIZE;
407 }
408 }
409
410 if (((attr->ia_valid & ATTR_UID) &&
411 (attr->ia_uid != sbi->options.fs_uid)) ||
412 ((attr->ia_valid & ATTR_GID) &&
413 (attr->ia_gid != sbi->options.fs_gid)) ||
414 ((attr->ia_valid & ATTR_MODE) &&
415 (attr->ia_mode & ~FAT_VALID_MODE)))
416 error = -EPERM;
417
418 if (error) {
419 if (sbi->options.quiet)
420 error = 0;
421 goto out;
422 }
423
424 /*
425 * We don't return -EPERM here. Yes, strange, but this is too
426 * old behavior.
427 */
428 if (attr->ia_valid & ATTR_MODE) {
429 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
430 attr->ia_valid &= ~ATTR_MODE;
431 }
432
433 if (attr->ia_valid & ATTR_SIZE) {
434 down_write(&MSDOS_I(inode)->truncate_lock);
435 truncate_setsize(inode, attr->ia_size);
436 fat_truncate_blocks(inode, attr->ia_size);
437 up_write(&MSDOS_I(inode)->truncate_lock);
438 }
439
440 setattr_copy(inode, attr);
441 mark_inode_dirty(inode);
442 out:
443 return error;
444 }
445 EXPORT_SYMBOL_GPL(fat_setattr);
446
447 const struct inode_operations fat_file_inode_operations = {
448 .setattr = fat_setattr,
449 .getattr = fat_getattr,
450 };
451