1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * linux/fs/fat/file.c
4 *
5 * Written 1992,1993 by Werner Almesberger
6 *
7 * regular file handling primitives for fat-based filesystems
8 */
9
10 #include <linux/capability.h>
11 #include <linux/module.h>
12 #include <linux/compat.h>
13 #include <linux/mount.h>
14 #include <linux/blkdev.h>
15 #include <linux/backing-dev.h>
16 #include <linux/filelock.h>
17 #include <linux/fsnotify.h>
18 #include <linux/security.h>
19 #include <linux/falloc.h>
20 #include "fat.h"
21
22 static long fat_fallocate(struct file *file, int mode,
23 loff_t offset, loff_t len);
24
fat_ioctl_get_attributes(struct inode * inode,u32 __user * user_attr)25 static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
26 {
27 u32 attr;
28
29 inode_lock_shared(inode);
30 attr = fat_make_attrs(inode);
31 inode_unlock_shared(inode);
32
33 return put_user(attr, user_attr);
34 }
35
fat_ioctl_set_attributes(struct file * file,u32 __user * user_attr)36 static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
37 {
38 struct inode *inode = file_inode(file);
39 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
40 int is_dir = S_ISDIR(inode->i_mode);
41 u32 attr, oldattr;
42 struct iattr ia;
43 int err;
44
45 err = get_user(attr, user_attr);
46 if (err)
47 goto out;
48
49 err = mnt_want_write_file(file);
50 if (err)
51 goto out;
52 inode_lock(inode);
53
54 /*
55 * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
56 * prevents the user from turning us into a VFAT
57 * longname entry. Also, we obviously can't set
58 * any of the NTFS attributes in the high 24 bits.
59 */
60 attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);
61 /* Merge in ATTR_VOLUME and ATTR_DIR */
62 attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
63 (is_dir ? ATTR_DIR : 0);
64 oldattr = fat_make_attrs(inode);
65
66 /* Equivalent to a chmod() */
67 ia.ia_valid = ATTR_MODE | ATTR_CTIME;
68 ia.ia_ctime = current_time(inode);
69 if (is_dir)
70 ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
71 else {
72 ia.ia_mode = fat_make_mode(sbi, attr,
73 S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));
74 }
75
76 /* The root directory has no attributes */
77 if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
78 err = -EINVAL;
79 goto out_unlock_inode;
80 }
81
82 if (sbi->options.sys_immutable &&
83 ((attr | oldattr) & ATTR_SYS) &&
84 !capable(CAP_LINUX_IMMUTABLE)) {
85 err = -EPERM;
86 goto out_unlock_inode;
87 }
88
89 /*
90 * The security check is questionable... We single
91 * out the RO attribute for checking by the security
92 * module, just because it maps to a file mode.
93 */
94 err = security_inode_setattr(file_mnt_idmap(file),
95 file->f_path.dentry, &ia);
96 if (err)
97 goto out_unlock_inode;
98
99 /* This MUST be done before doing anything irreversible... */
100 err = fat_setattr(file_mnt_idmap(file), file->f_path.dentry, &ia);
101 if (err)
102 goto out_unlock_inode;
103
104 fsnotify_change(file->f_path.dentry, ia.ia_valid);
105 if (sbi->options.sys_immutable) {
106 if (attr & ATTR_SYS)
107 inode->i_flags |= S_IMMUTABLE;
108 else
109 inode->i_flags &= ~S_IMMUTABLE;
110 }
111
112 fat_save_attrs(inode, attr);
113 mark_inode_dirty(inode);
114 out_unlock_inode:
115 inode_unlock(inode);
116 mnt_drop_write_file(file);
117 out:
118 return err;
119 }
120
fat_ioctl_get_volume_id(struct inode * inode,u32 __user * user_attr)121 static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)
122 {
123 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
124 return put_user(sbi->vol_id, user_attr);
125 }
126
fat_ioctl_fitrim(struct inode * inode,unsigned long arg)127 static int fat_ioctl_fitrim(struct inode *inode, unsigned long arg)
128 {
129 struct super_block *sb = inode->i_sb;
130 struct fstrim_range __user *user_range;
131 struct fstrim_range range;
132 int err;
133
134 if (!capable(CAP_SYS_ADMIN))
135 return -EPERM;
136
137 if (!bdev_max_discard_sectors(sb->s_bdev))
138 return -EOPNOTSUPP;
139
140 user_range = (struct fstrim_range __user *)arg;
141 if (copy_from_user(&range, user_range, sizeof(range)))
142 return -EFAULT;
143
144 range.minlen = max(range.minlen, bdev_discard_granularity(sb->s_bdev));
145
146 err = fat_trim_fs(inode, &range);
147 if (err < 0)
148 return err;
149
150 if (copy_to_user(user_range, &range, sizeof(range)))
151 return -EFAULT;
152
153 return 0;
154 }
155
fat_generic_ioctl(struct file * filp,unsigned int cmd,unsigned long arg)156 long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
157 {
158 struct inode *inode = file_inode(filp);
159 u32 __user *user_attr = (u32 __user *)arg;
160
161 switch (cmd) {
162 case FAT_IOCTL_GET_ATTRIBUTES:
163 return fat_ioctl_get_attributes(inode, user_attr);
164 case FAT_IOCTL_SET_ATTRIBUTES:
165 return fat_ioctl_set_attributes(filp, user_attr);
166 case FAT_IOCTL_GET_VOLUME_ID:
167 return fat_ioctl_get_volume_id(inode, user_attr);
168 case FITRIM:
169 return fat_ioctl_fitrim(inode, arg);
170 default:
171 return -ENOTTY; /* Inappropriate ioctl for device */
172 }
173 }
174
fat_file_release(struct inode * inode,struct file * filp)175 static int fat_file_release(struct inode *inode, struct file *filp)
176 {
177 if ((filp->f_mode & FMODE_WRITE) &&
178 MSDOS_SB(inode->i_sb)->options.flush) {
179 fat_flush_inodes(inode->i_sb, inode, NULL);
180 set_current_state(TASK_UNINTERRUPTIBLE);
181 io_schedule_timeout(HZ/10);
182 }
183 return 0;
184 }
185
fat_file_fsync(struct file * filp,loff_t start,loff_t end,int datasync)186 int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
187 {
188 struct inode *inode = filp->f_mapping->host;
189 int err;
190
191 err = __generic_file_fsync(filp, start, end, datasync);
192 if (err)
193 return err;
194
195 err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
196 if (err)
197 return err;
198
199 return blkdev_issue_flush(inode->i_sb->s_bdev);
200 }
201
202
203 const struct file_operations fat_file_operations = {
204 .llseek = generic_file_llseek,
205 .read_iter = generic_file_read_iter,
206 .write_iter = generic_file_write_iter,
207 .mmap_prepare = generic_file_mmap_prepare,
208 .release = fat_file_release,
209 .unlocked_ioctl = fat_generic_ioctl,
210 .compat_ioctl = compat_ptr_ioctl,
211 .fsync = fat_file_fsync,
212 .splice_read = filemap_splice_read,
213 .splice_write = iter_file_splice_write,
214 .fallocate = fat_fallocate,
215 .setlease = generic_setlease,
216 };
217
fat_cont_expand(struct inode * inode,loff_t size)218 static int fat_cont_expand(struct inode *inode, loff_t size)
219 {
220 struct address_space *mapping = inode->i_mapping;
221 loff_t start = inode->i_size, count = size - inode->i_size;
222 int err;
223
224 err = generic_cont_expand_simple(inode, size);
225 if (err)
226 goto out;
227
228 fat_truncate_time(inode, NULL, FAT_UPDATE_CMTIME);
229 mark_inode_dirty(inode);
230 if (IS_SYNC(inode)) {
231 int err2;
232
233 /*
234 * Opencode syncing since we don't have a file open to use
235 * standard fsync path.
236 */
237 err = filemap_fdatawrite_range(mapping, start,
238 start + count - 1);
239 err2 = sync_mapping_buffers(mapping);
240 if (!err)
241 err = err2;
242 err2 = write_inode_now(inode, 1);
243 if (!err)
244 err = err2;
245 if (!err) {
246 err = filemap_fdatawait_range(mapping, start,
247 start + count - 1);
248 }
249 }
250 out:
251 return err;
252 }
253
254 /*
255 * Preallocate space for a file. This implements fat's fallocate file
256 * operation, which gets called from sys_fallocate system call. User
257 * space requests len bytes at offset. If FALLOC_FL_KEEP_SIZE is set
258 * we just allocate clusters without zeroing them out. Otherwise we
259 * allocate and zero out clusters via an expanding truncate.
260 */
fat_fallocate(struct file * file,int mode,loff_t offset,loff_t len)261 static long fat_fallocate(struct file *file, int mode,
262 loff_t offset, loff_t len)
263 {
264 int nr_cluster; /* Number of clusters to be allocated */
265 loff_t mm_bytes; /* Number of bytes to be allocated for file */
266 loff_t ondisksize; /* block aligned on-disk size in bytes*/
267 struct inode *inode = file->f_mapping->host;
268 struct super_block *sb = inode->i_sb;
269 struct msdos_sb_info *sbi = MSDOS_SB(sb);
270 int err = 0;
271
272 /* No support for hole punch or other fallocate flags. */
273 if (mode & ~FALLOC_FL_KEEP_SIZE)
274 return -EOPNOTSUPP;
275
276 /* No support for dir */
277 if (!S_ISREG(inode->i_mode))
278 return -EOPNOTSUPP;
279
280 inode_lock(inode);
281 if (mode & FALLOC_FL_KEEP_SIZE) {
282 ondisksize = inode->i_blocks << 9;
283 if ((offset + len) <= ondisksize)
284 goto error;
285
286 /* First compute the number of clusters to be allocated */
287 mm_bytes = offset + len - ondisksize;
288 nr_cluster = (mm_bytes + (sbi->cluster_size - 1)) >>
289 sbi->cluster_bits;
290
291 /* Start the allocation.We are not zeroing out the clusters */
292 while (nr_cluster-- > 0) {
293 err = fat_add_cluster(inode);
294 if (err)
295 goto error;
296 }
297 } else {
298 if ((offset + len) <= i_size_read(inode))
299 goto error;
300
301 /* This is just an expanding truncate */
302 err = fat_cont_expand(inode, (offset + len));
303 }
304
305 error:
306 inode_unlock(inode);
307 return err;
308 }
309
310 /* Free all clusters after the skip'th cluster. */
fat_free(struct inode * inode,int skip)311 static int fat_free(struct inode *inode, int skip)
312 {
313 struct super_block *sb = inode->i_sb;
314 int err, wait, free_start, i_start, i_logstart;
315
316 if (MSDOS_I(inode)->i_start == 0)
317 return 0;
318
319 fat_cache_inval_inode(inode);
320
321 wait = IS_DIRSYNC(inode);
322 i_start = free_start = MSDOS_I(inode)->i_start;
323 i_logstart = MSDOS_I(inode)->i_logstart;
324
325 /* First, we write the new file size. */
326 if (!skip) {
327 MSDOS_I(inode)->i_start = 0;
328 MSDOS_I(inode)->i_logstart = 0;
329 }
330 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
331 fat_truncate_time(inode, NULL, FAT_UPDATE_CMTIME);
332 if (wait) {
333 err = fat_sync_inode(inode);
334 if (err) {
335 MSDOS_I(inode)->i_start = i_start;
336 MSDOS_I(inode)->i_logstart = i_logstart;
337 return err;
338 }
339 } else
340 mark_inode_dirty(inode);
341
342 /* Write a new EOF, and get the remaining cluster chain for freeing. */
343 if (skip) {
344 struct fat_entry fatent;
345 int ret, fclus, dclus;
346
347 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
348 if (ret < 0)
349 return ret;
350 else if (ret == FAT_ENT_EOF)
351 return 0;
352
353 fatent_init(&fatent);
354 ret = fat_ent_read(inode, &fatent, dclus);
355 if (ret == FAT_ENT_EOF) {
356 fatent_brelse(&fatent);
357 return 0;
358 } else if (ret == FAT_ENT_FREE) {
359 fat_fs_error(sb,
360 "%s: invalid cluster chain (i_pos %lld)",
361 __func__, MSDOS_I(inode)->i_pos);
362 ret = -EIO;
363 } else if (ret > 0) {
364 err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
365 if (err)
366 ret = err;
367 }
368 fatent_brelse(&fatent);
369 if (ret < 0)
370 return ret;
371
372 free_start = ret;
373 }
374 inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
375
376 /* Freeing the remained cluster chain */
377 return fat_free_clusters(inode, free_start);
378 }
379
fat_truncate_blocks(struct inode * inode,loff_t offset)380 void fat_truncate_blocks(struct inode *inode, loff_t offset)
381 {
382 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
383 const unsigned int cluster_size = sbi->cluster_size;
384 int nr_clusters;
385
386 /*
387 * This protects against truncating a file bigger than it was then
388 * trying to write into the hole.
389 */
390 if (MSDOS_I(inode)->mmu_private > offset)
391 MSDOS_I(inode)->mmu_private = offset;
392
393 nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
394
395 fat_free(inode, nr_clusters);
396 fat_flush_inodes(inode->i_sb, inode, NULL);
397 }
398
fat_getattr(struct mnt_idmap * idmap,const struct path * path,struct kstat * stat,u32 request_mask,unsigned int flags)399 int fat_getattr(struct mnt_idmap *idmap, const struct path *path,
400 struct kstat *stat, u32 request_mask, unsigned int flags)
401 {
402 struct inode *inode = d_inode(path->dentry);
403 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
404
405 generic_fillattr(idmap, request_mask, inode, stat);
406 stat->blksize = sbi->cluster_size;
407
408 if (sbi->options.nfs == FAT_NFS_NOSTALE_RO) {
409 /* Use i_pos for ino. This is used as fileid of nfs. */
410 stat->ino = fat_i_pos_read(sbi, inode);
411 }
412
413 if (sbi->options.isvfat && request_mask & STATX_BTIME) {
414 stat->result_mask |= STATX_BTIME;
415 stat->btime = MSDOS_I(inode)->i_crtime;
416 }
417
418 return 0;
419 }
420 EXPORT_SYMBOL_GPL(fat_getattr);
421
fat_sanitize_mode(const struct msdos_sb_info * sbi,struct inode * inode,umode_t * mode_ptr)422 static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
423 struct inode *inode, umode_t *mode_ptr)
424 {
425 umode_t mask, perm;
426
427 /*
428 * Note, the basic check is already done by a caller of
429 * (attr->ia_mode & ~FAT_VALID_MODE)
430 */
431
432 if (S_ISREG(inode->i_mode))
433 mask = sbi->options.fs_fmask;
434 else
435 mask = sbi->options.fs_dmask;
436
437 perm = *mode_ptr & ~(S_IFMT | mask);
438
439 /*
440 * Of the r and x bits, all (subject to umask) must be present. Of the
441 * w bits, either all (subject to umask) or none must be present.
442 *
443 * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
444 */
445 if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
446 return -EPERM;
447 if (fat_mode_can_hold_ro(inode)) {
448 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
449 return -EPERM;
450 } else {
451 if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
452 return -EPERM;
453 }
454
455 *mode_ptr &= S_IFMT | perm;
456
457 return 0;
458 }
459
fat_allow_set_time(struct mnt_idmap * idmap,struct msdos_sb_info * sbi,struct inode * inode)460 static int fat_allow_set_time(struct mnt_idmap *idmap,
461 struct msdos_sb_info *sbi, struct inode *inode)
462 {
463 umode_t allow_utime = sbi->options.allow_utime;
464
465 if (!vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode),
466 current_fsuid())) {
467 if (vfsgid_in_group_p(i_gid_into_vfsgid(idmap, inode)))
468 allow_utime >>= 3;
469 if (allow_utime & MAY_WRITE)
470 return 1;
471 }
472
473 /* use a default check */
474 return 0;
475 }
476
477 #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
478 /* valid file mode bits */
479 #define FAT_VALID_MODE (S_IFREG | S_IFDIR | S_IRWXUGO)
480
fat_setattr(struct mnt_idmap * idmap,struct dentry * dentry,struct iattr * attr)481 int fat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
482 struct iattr *attr)
483 {
484 struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
485 struct inode *inode = d_inode(dentry);
486 unsigned int ia_valid;
487 int error;
488
489 /* Check for setting the inode time. */
490 ia_valid = attr->ia_valid;
491 if (ia_valid & TIMES_SET_FLAGS) {
492 if (fat_allow_set_time(idmap, sbi, inode))
493 attr->ia_valid &= ~TIMES_SET_FLAGS;
494 }
495
496 error = setattr_prepare(idmap, dentry, attr);
497 attr->ia_valid = ia_valid;
498 if (error) {
499 if (sbi->options.quiet)
500 error = 0;
501 goto out;
502 }
503
504 /*
505 * Expand the file. Since inode_setattr() updates ->i_size
506 * before calling the ->truncate(), but FAT needs to fill the
507 * hole before it. XXX: this is no longer true with new truncate
508 * sequence.
509 */
510 if (attr->ia_valid & ATTR_SIZE) {
511 inode_dio_wait(inode);
512
513 if (attr->ia_size > inode->i_size) {
514 error = fat_cont_expand(inode, attr->ia_size);
515 if (error || attr->ia_valid == ATTR_SIZE)
516 goto out;
517 attr->ia_valid &= ~ATTR_SIZE;
518 }
519 }
520
521 if (((attr->ia_valid & ATTR_UID) &&
522 (!uid_eq(from_vfsuid(idmap, i_user_ns(inode), attr->ia_vfsuid),
523 sbi->options.fs_uid))) ||
524 ((attr->ia_valid & ATTR_GID) &&
525 (!gid_eq(from_vfsgid(idmap, i_user_ns(inode), attr->ia_vfsgid),
526 sbi->options.fs_gid))) ||
527 ((attr->ia_valid & ATTR_MODE) &&
528 (attr->ia_mode & ~FAT_VALID_MODE)))
529 error = -EPERM;
530
531 if (error) {
532 if (sbi->options.quiet)
533 error = 0;
534 goto out;
535 }
536
537 /*
538 * We don't return -EPERM here. Yes, strange, but this is too
539 * old behavior.
540 */
541 if (attr->ia_valid & ATTR_MODE) {
542 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
543 attr->ia_valid &= ~ATTR_MODE;
544 }
545
546 if (attr->ia_valid & ATTR_SIZE) {
547 error = fat_block_truncate_page(inode, attr->ia_size);
548 if (error)
549 goto out;
550 down_write(&MSDOS_I(inode)->truncate_lock);
551 truncate_setsize(inode, attr->ia_size);
552 fat_truncate_blocks(inode, attr->ia_size);
553 up_write(&MSDOS_I(inode)->truncate_lock);
554 }
555
556 /*
557 * setattr_copy can't truncate these appropriately, so we'll copy them
558 * ourselves. See fat_truncate_time for the c/mtime logic on fat.
559 */
560 if (attr->ia_valid & ATTR_ATIME)
561 fat_truncate_time(inode, &attr->ia_atime, FAT_UPDATE_ATIME);
562 if (attr->ia_valid & ATTR_MTIME)
563 fat_truncate_time(inode, &attr->ia_mtime, FAT_UPDATE_CMTIME);
564 attr->ia_valid &= ~(ATTR_ATIME|ATTR_CTIME|ATTR_MTIME);
565
566 setattr_copy(idmap, inode, attr);
567 mark_inode_dirty(inode);
568 out:
569 return error;
570 }
571 EXPORT_SYMBOL_GPL(fat_setattr);
572
573 const struct inode_operations fat_file_inode_operations = {
574 .setattr = fat_setattr,
575 .getattr = fat_getattr,
576 .update_time = fat_update_time,
577 };
578