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Commit | Line | Data |
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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 | }; |