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