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 struct inode *fat_inode = MSDOS_SB(inode->i_sb)->fat_inode;
190 int err;
191
192 err = mmb_fsync_noflush(filp, &MSDOS_I(inode)->i_metadata_bhs,
193 start, end, datasync);
194 if (err)
195 return err;
196
197 err = mmb_sync(&MSDOS_I(fat_inode)->i_metadata_bhs);
198 if (err)
199 return err;
200
201 return blkdev_issue_flush(inode->i_sb->s_bdev);
202 }
203
204
205 const struct file_operations fat_file_operations = {
206 .llseek = generic_file_llseek,
207 .read_iter = generic_file_read_iter,
208 .write_iter = generic_file_write_iter,
209 .mmap_prepare = generic_file_mmap_prepare,
210 .release = fat_file_release,
211 .unlocked_ioctl = fat_generic_ioctl,
212 .compat_ioctl = compat_ptr_ioctl,
213 .fsync = fat_file_fsync,
214 .splice_read = filemap_splice_read,
215 .splice_write = iter_file_splice_write,
216 .fallocate = fat_fallocate,
217 .setlease = generic_setlease,
218 };
219
fat_cont_expand(struct inode * inode,loff_t size)220 static int fat_cont_expand(struct inode *inode, loff_t size)
221 {
222 struct address_space *mapping = inode->i_mapping;
223 loff_t start = inode->i_size, count = size - inode->i_size;
224 int err;
225
226 err = generic_cont_expand_simple(inode, size);
227 if (err)
228 goto out;
229
230 fat_truncate_time(inode, NULL, FAT_UPDATE_CMTIME);
231 mark_inode_dirty(inode);
232 if (IS_SYNC(inode)) {
233 int err2;
234
235 /*
236 * Opencode syncing since we don't have a file open to use
237 * standard fsync path.
238 */
239 err = filemap_fdatawrite_range(mapping, start,
240 start + count - 1);
241 err2 = mmb_sync(&MSDOS_I(inode)->i_metadata_bhs);
242 if (!err)
243 err = err2;
244 err2 = write_inode_now(inode, 1);
245 if (!err)
246 err = err2;
247 if (!err) {
248 err = filemap_fdatawait_range(mapping, start,
249 start + count - 1);
250 }
251 }
252 out:
253 return err;
254 }
255
256 /*
257 * Preallocate space for a file. This implements fat's fallocate file
258 * operation, which gets called from sys_fallocate system call. User
259 * space requests len bytes at offset. If FALLOC_FL_KEEP_SIZE is set
260 * we just allocate clusters without zeroing them out. Otherwise we
261 * allocate and zero out clusters via an expanding truncate.
262 */
fat_fallocate(struct file * file,int mode,loff_t offset,loff_t len)263 static long fat_fallocate(struct file *file, int mode,
264 loff_t offset, loff_t len)
265 {
266 int nr_cluster; /* Number of clusters to be allocated */
267 loff_t mm_bytes; /* Number of bytes to be allocated for file */
268 loff_t ondisksize; /* block aligned on-disk size in bytes*/
269 struct inode *inode = file->f_mapping->host;
270 struct super_block *sb = inode->i_sb;
271 struct msdos_sb_info *sbi = MSDOS_SB(sb);
272 int err = 0;
273
274 /* No support for hole punch or other fallocate flags. */
275 if (mode & ~FALLOC_FL_KEEP_SIZE)
276 return -EOPNOTSUPP;
277
278 /* No support for dir */
279 if (!S_ISREG(inode->i_mode))
280 return -EOPNOTSUPP;
281
282 inode_lock(inode);
283 if (mode & FALLOC_FL_KEEP_SIZE) {
284 ondisksize = inode->i_blocks << 9;
285 if ((offset + len) <= ondisksize)
286 goto error;
287
288 /* First compute the number of clusters to be allocated */
289 mm_bytes = offset + len - ondisksize;
290 nr_cluster = (mm_bytes + (sbi->cluster_size - 1)) >>
291 sbi->cluster_bits;
292
293 /* Start the allocation.We are not zeroing out the clusters */
294 while (nr_cluster-- > 0) {
295 err = fat_add_cluster(inode);
296 if (err)
297 goto error;
298 }
299 } else {
300 if ((offset + len) <= i_size_read(inode))
301 goto error;
302
303 /* This is just an expanding truncate */
304 err = fat_cont_expand(inode, (offset + len));
305 }
306
307 error:
308 inode_unlock(inode);
309 return err;
310 }
311
312 /* Free all clusters after the skip'th cluster. */
fat_free(struct inode * inode,int skip)313 static int fat_free(struct inode *inode, int skip)
314 {
315 struct super_block *sb = inode->i_sb;
316 int err, wait, free_start, i_start, i_logstart;
317
318 if (MSDOS_I(inode)->i_start == 0)
319 return 0;
320
321 fat_cache_inval_inode(inode);
322
323 wait = IS_DIRSYNC(inode);
324 i_start = free_start = MSDOS_I(inode)->i_start;
325 i_logstart = MSDOS_I(inode)->i_logstart;
326
327 /* First, we write the new file size. */
328 if (!skip) {
329 MSDOS_I(inode)->i_start = 0;
330 MSDOS_I(inode)->i_logstart = 0;
331 }
332 MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
333 fat_truncate_time(inode, NULL, FAT_UPDATE_CMTIME);
334 if (wait) {
335 err = fat_sync_inode(inode);
336 if (err) {
337 MSDOS_I(inode)->i_start = i_start;
338 MSDOS_I(inode)->i_logstart = i_logstart;
339 return err;
340 }
341 } else
342 mark_inode_dirty(inode);
343
344 /* Write a new EOF, and get the remaining cluster chain for freeing. */
345 if (skip) {
346 struct fat_entry fatent;
347 int ret, fclus, dclus;
348
349 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
350 if (ret < 0)
351 return ret;
352 else if (ret == FAT_ENT_EOF)
353 return 0;
354
355 fatent_init(&fatent);
356 ret = fat_ent_read(inode, &fatent, dclus);
357 if (ret == FAT_ENT_EOF) {
358 fatent_brelse(&fatent);
359 return 0;
360 } else if (ret == FAT_ENT_FREE) {
361 fat_fs_error(sb,
362 "%s: invalid cluster chain (i_pos %lld)",
363 __func__, MSDOS_I(inode)->i_pos);
364 ret = -EIO;
365 } else if (ret > 0) {
366 err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
367 if (err)
368 ret = err;
369 }
370 fatent_brelse(&fatent);
371 if (ret < 0)
372 return ret;
373
374 free_start = ret;
375 }
376 inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
377
378 /* Freeing the remained cluster chain */
379 return fat_free_clusters(inode, free_start);
380 }
381
fat_truncate_blocks(struct inode * inode,loff_t offset)382 void fat_truncate_blocks(struct inode *inode, loff_t offset)
383 {
384 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
385 const unsigned int cluster_size = sbi->cluster_size;
386 int nr_clusters;
387
388 /*
389 * This protects against truncating a file bigger than it was then
390 * trying to write into the hole.
391 */
392 if (MSDOS_I(inode)->mmu_private > offset)
393 MSDOS_I(inode)->mmu_private = offset;
394
395 nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
396
397 fat_free(inode, nr_clusters);
398 fat_flush_inodes(inode->i_sb, inode, NULL);
399 }
400
fat_getattr(struct mnt_idmap * idmap,const struct path * path,struct kstat * stat,u32 request_mask,unsigned int flags)401 int fat_getattr(struct mnt_idmap *idmap, const struct path *path,
402 struct kstat *stat, u32 request_mask, unsigned int flags)
403 {
404 struct inode *inode = d_inode(path->dentry);
405 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
406
407 generic_fillattr(idmap, request_mask, inode, stat);
408 stat->blksize = sbi->cluster_size;
409
410 if (sbi->options.nfs == FAT_NFS_NOSTALE_RO) {
411 /* Use i_pos for ino. This is used as fileid of nfs. */
412 stat->ino = fat_i_pos_read(sbi, inode);
413 }
414
415 if (sbi->options.isvfat && request_mask & STATX_BTIME) {
416 stat->result_mask |= STATX_BTIME;
417 stat->btime = MSDOS_I(inode)->i_crtime;
418 }
419
420 return 0;
421 }
422 EXPORT_SYMBOL_GPL(fat_getattr);
423
fat_sanitize_mode(const struct msdos_sb_info * sbi,struct inode * inode,umode_t * mode_ptr)424 static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
425 struct inode *inode, umode_t *mode_ptr)
426 {
427 umode_t mask, perm;
428
429 /*
430 * Note, the basic check is already done by a caller of
431 * (attr->ia_mode & ~FAT_VALID_MODE)
432 */
433
434 if (S_ISREG(inode->i_mode))
435 mask = sbi->options.fs_fmask;
436 else
437 mask = sbi->options.fs_dmask;
438
439 perm = *mode_ptr & ~(S_IFMT | mask);
440
441 /*
442 * Of the r and x bits, all (subject to umask) must be present. Of the
443 * w bits, either all (subject to umask) or none must be present.
444 *
445 * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
446 */
447 if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
448 return -EPERM;
449 if (fat_mode_can_hold_ro(inode)) {
450 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
451 return -EPERM;
452 } else {
453 if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
454 return -EPERM;
455 }
456
457 *mode_ptr &= S_IFMT | perm;
458
459 return 0;
460 }
461
fat_allow_set_time(struct mnt_idmap * idmap,struct msdos_sb_info * sbi,struct inode * inode)462 static int fat_allow_set_time(struct mnt_idmap *idmap,
463 struct msdos_sb_info *sbi, struct inode *inode)
464 {
465 umode_t allow_utime = sbi->options.allow_utime;
466
467 if (!vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode),
468 current_fsuid())) {
469 if (vfsgid_in_group_p(i_gid_into_vfsgid(idmap, inode)))
470 allow_utime >>= 3;
471 if (allow_utime & MAY_WRITE)
472 return 1;
473 }
474
475 /* use a default check */
476 return 0;
477 }
478
479 #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
480 /* valid file mode bits */
481 #define FAT_VALID_MODE (S_IFREG | S_IFDIR | S_IRWXUGO)
482
fat_setattr(struct mnt_idmap * idmap,struct dentry * dentry,struct iattr * attr)483 int fat_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
484 struct iattr *attr)
485 {
486 struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
487 struct inode *inode = d_inode(dentry);
488 unsigned int ia_valid;
489 int error;
490
491 /* Check for setting the inode time. */
492 ia_valid = attr->ia_valid;
493 if (ia_valid & TIMES_SET_FLAGS) {
494 if (fat_allow_set_time(idmap, sbi, inode))
495 attr->ia_valid &= ~TIMES_SET_FLAGS;
496 }
497
498 error = setattr_prepare(idmap, dentry, attr);
499 attr->ia_valid = ia_valid;
500 if (error) {
501 if (sbi->options.quiet)
502 error = 0;
503 goto out;
504 }
505
506 /*
507 * Expand the file. Since inode_setattr() updates ->i_size
508 * before calling the ->truncate(), but FAT needs to fill the
509 * hole before it. XXX: this is no longer true with new truncate
510 * sequence.
511 */
512 if (attr->ia_valid & ATTR_SIZE) {
513 inode_dio_wait(inode);
514
515 if (attr->ia_size > inode->i_size) {
516 error = fat_cont_expand(inode, attr->ia_size);
517 if (error || attr->ia_valid == ATTR_SIZE)
518 goto out;
519 attr->ia_valid &= ~ATTR_SIZE;
520 }
521 }
522
523 if (((attr->ia_valid & ATTR_UID) &&
524 (!uid_eq(from_vfsuid(idmap, i_user_ns(inode), attr->ia_vfsuid),
525 sbi->options.fs_uid))) ||
526 ((attr->ia_valid & ATTR_GID) &&
527 (!gid_eq(from_vfsgid(idmap, i_user_ns(inode), attr->ia_vfsgid),
528 sbi->options.fs_gid))) ||
529 ((attr->ia_valid & ATTR_MODE) &&
530 (attr->ia_mode & ~FAT_VALID_MODE)))
531 error = -EPERM;
532
533 if (error) {
534 if (sbi->options.quiet)
535 error = 0;
536 goto out;
537 }
538
539 /*
540 * We don't return -EPERM here. Yes, strange, but this is too
541 * old behavior.
542 */
543 if (attr->ia_valid & ATTR_MODE) {
544 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
545 attr->ia_valid &= ~ATTR_MODE;
546 }
547
548 if (attr->ia_valid & ATTR_SIZE) {
549 error = fat_block_truncate_page(inode, attr->ia_size);
550 if (error)
551 goto out;
552 down_write(&MSDOS_I(inode)->truncate_lock);
553 truncate_setsize(inode, attr->ia_size);
554 fat_truncate_blocks(inode, attr->ia_size);
555 up_write(&MSDOS_I(inode)->truncate_lock);
556 }
557
558 /*
559 * setattr_copy can't truncate these appropriately, so we'll copy them
560 * ourselves. See fat_truncate_time for the c/mtime logic on fat.
561 */
562 if (attr->ia_valid & ATTR_ATIME)
563 fat_truncate_time(inode, &attr->ia_atime, FAT_UPDATE_ATIME);
564 if (attr->ia_valid & ATTR_MTIME)
565 fat_truncate_time(inode, &attr->ia_mtime, FAT_UPDATE_CMTIME);
566 attr->ia_valid &= ~(ATTR_ATIME|ATTR_CTIME|ATTR_MTIME);
567
568 setattr_copy(idmap, inode, attr);
569 mark_inode_dirty(inode);
570 out:
571 return error;
572 }
573 EXPORT_SYMBOL_GPL(fat_setattr);
574
575 const struct inode_operations fat_file_inode_operations = {
576 .setattr = fat_setattr,
577 .getattr = fat_getattr,
578 .update_time = fat_update_time,
579 };
580