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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 <linux/fileattr.h>
21#include "fat.h"
22
23static long fat_fallocate(struct file *file, int mode,
24 loff_t offset, loff_t len);
25
26static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
27{
28 u32 attr;
29
30 inode_lock_shared(inode);
31 attr = fat_make_attrs(inode);
32 inode_unlock_shared(inode);
33
34 return put_user(attr, user_attr);
35}
36
37static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
38{
39 struct inode *inode = file_inode(file);
40 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
41 int is_dir = S_ISDIR(inode->i_mode);
42 u32 attr, oldattr;
43 struct iattr ia;
44 int err;
45
46 err = get_user(attr, user_attr);
47 if (err)
48 goto out;
49
50 err = mnt_want_write_file(file);
51 if (err)
52 goto out;
53 inode_lock(inode);
54
55 /*
56 * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
57 * prevents the user from turning us into a VFAT
58 * longname entry. Also, we obviously can't set
59 * any of the NTFS attributes in the high 24 bits.
60 */
61 attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);
62 /* Merge in ATTR_VOLUME and ATTR_DIR */
63 attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
64 (is_dir ? ATTR_DIR : 0);
65 oldattr = fat_make_attrs(inode);
66
67 /* Equivalent to a chmod() */
68 ia.ia_valid = ATTR_MODE | ATTR_CTIME;
69 ia.ia_ctime = current_time(inode);
70 if (is_dir)
71 ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
72 else {
73 ia.ia_mode = fat_make_mode(sbi, attr,
74 S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));
75 }
76
77 /* The root directory has no attributes */
78 if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
79 err = -EINVAL;
80 goto out_unlock_inode;
81 }
82
83 if (sbi->options.sys_immutable &&
84 ((attr | oldattr) & ATTR_SYS) &&
85 !capable(CAP_LINUX_IMMUTABLE)) {
86 err = -EPERM;
87 goto out_unlock_inode;
88 }
89
90 /*
91 * The security check is questionable... We single
92 * out the RO attribute for checking by the security
93 * module, just because it maps to a file mode.
94 */
95 err = security_inode_setattr(file_mnt_idmap(file),
96 file->f_path.dentry, &ia);
97 if (err)
98 goto out_unlock_inode;
99
100 /* This MUST be done before doing anything irreversible... */
101 err = fat_setattr(file_mnt_idmap(file), file->f_path.dentry, &ia);
102 if (err)
103 goto out_unlock_inode;
104
105 fsnotify_change(file->f_path.dentry, ia.ia_valid);
106 if (sbi->options.sys_immutable) {
107 if (attr & ATTR_SYS)
108 inode->i_flags |= S_IMMUTABLE;
109 else
110 inode->i_flags &= ~S_IMMUTABLE;
111 }
112
113 fat_save_attrs(inode, attr);
114 mark_inode_dirty(inode);
115out_unlock_inode:
116 inode_unlock(inode);
117 mnt_drop_write_file(file);
118out:
119 return err;
120}
121
122static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)
123{
124 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
125 return put_user(sbi->vol_id, user_attr);
126}
127
128static int fat_ioctl_fitrim(struct inode *inode, unsigned long arg)
129{
130 struct super_block *sb = inode->i_sb;
131 struct fstrim_range __user *user_range;
132 struct fstrim_range range;
133 int err;
134
135 if (!capable(CAP_SYS_ADMIN))
136 return -EPERM;
137
138 if (!bdev_max_discard_sectors(sb->s_bdev))
139 return -EOPNOTSUPP;
140
141 user_range = (struct fstrim_range __user *)arg;
142 if (copy_from_user(&range, user_range, sizeof(range)))
143 return -EFAULT;
144
145 range.minlen = max(range.minlen, bdev_discard_granularity(sb->s_bdev));
146
147 err = fat_trim_fs(inode, &range);
148 if (err < 0)
149 return err;
150
151 if (copy_to_user(user_range, &range, sizeof(range)))
152 return -EFAULT;
153
154 return 0;
155}
156
157long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
158{
159 struct inode *inode = file_inode(filp);
160 u32 __user *user_attr = (u32 __user *)arg;
161
162 switch (cmd) {
163 case FAT_IOCTL_GET_ATTRIBUTES:
164 return fat_ioctl_get_attributes(inode, user_attr);
165 case FAT_IOCTL_SET_ATTRIBUTES:
166 return fat_ioctl_set_attributes(filp, user_attr);
167 case FAT_IOCTL_GET_VOLUME_ID:
168 return fat_ioctl_get_volume_id(inode, user_attr);
169 case FITRIM:
170 return fat_ioctl_fitrim(inode, arg);
171 default:
172 return -ENOTTY; /* Inappropriate ioctl for device */
173 }
174}
175
176static int fat_file_release(struct inode *inode, struct file *filp)
177{
178 if ((filp->f_mode & FMODE_WRITE) &&
179 MSDOS_SB(inode->i_sb)->options.flush) {
180 fat_flush_inodes(inode->i_sb, inode, NULL);
181 set_current_state(TASK_UNINTERRUPTIBLE);
182 io_schedule_timeout(HZ/10);
183 }
184 return 0;
185}
186
187int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
188{
189 struct inode *inode = filp->f_mapping->host;
190 struct inode *fat_inode = MSDOS_SB(inode->i_sb)->fat_inode;
191 int err;
192
193 err = simple_fsync_noflush(filp, 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
205const 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
220static 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 }
252out:
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 */
263static 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
307error:
308 inode_unlock(inode);
309 return err;
310}
311
312/* Free all clusters after the skip'th cluster. */
313static 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 mark_inode_dirty(inode);
335 if (wait) {
336 err = sync_inode_metadata(inode, 1);
337 if (err) {
338 MSDOS_I(inode)->i_start = i_start;
339 MSDOS_I(inode)->i_logstart = i_logstart;
340 return err;
341 }
342 }
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
382void 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
401int fat_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
402{
403 struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
404 bool case_sensitive;
405
406 /*
407 * FAT filesystems are case-insensitive by default. VFAT
408 * becomes case-sensitive when mounted with 'check=strict',
409 * which installs vfat_dentry_ops. MSDOS has no such option;
410 * its 'nocase' mount option selects case-sensitive matching.
411 *
412 * VFAT long filename entries preserve case. Without VFAT, only
413 * uppercased 8.3 short names are stored. MSDOS with 'nocase'
414 * also preserves case.
415 */
416 if (sbi->options.isvfat)
417 case_sensitive = sbi->options.name_check == 's';
418 else
419 case_sensitive = sbi->options.nocase;
420
421 if (!case_sensitive) {
422 fa->fsx_xflags |= FS_XFLAG_CASEFOLD;
423 fa->flags |= FS_CASEFOLD_FL;
424 if (!sbi->options.isvfat)
425 fa->fsx_xflags |= FS_XFLAG_CASENONPRESERVING;
426 }
427 if (d_inode(dentry)->i_flags & S_IMMUTABLE) {
428 fa->fsx_xflags |= FS_XFLAG_IMMUTABLE;
429 fa->flags |= FS_IMMUTABLE_FL;
430 }
431 return 0;
432}
433EXPORT_SYMBOL_GPL(fat_fileattr_get);
434
435int fat_getattr(const struct mnt_idmap *idmap, const struct path *path,
436 struct kstat *stat, u32 request_mask, unsigned int flags)
437{
438 struct inode *inode = d_inode(path->dentry);
439 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
440
441 generic_fillattr(idmap, request_mask, inode, stat);
442 stat->blksize = sbi->cluster_size;
443
444 if (sbi->options.nfs == FAT_NFS_NOSTALE_RO) {
445 /* Use i_pos for ino. This is used as fileid of nfs. */
446 stat->ino = fat_i_pos_read(sbi, inode);
447 }
448
449 if (sbi->options.isvfat && request_mask & STATX_BTIME) {
450 stat->result_mask |= STATX_BTIME;
451 stat->btime = MSDOS_I(inode)->i_crtime;
452 }
453
454 return 0;
455}
456EXPORT_SYMBOL_GPL(fat_getattr);
457
458static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
459 struct inode *inode, umode_t *mode_ptr)
460{
461 umode_t mask, perm;
462
463 /*
464 * Note, the basic check is already done by a caller of
465 * (attr->ia_mode & ~FAT_VALID_MODE)
466 */
467
468 if (S_ISREG(inode->i_mode))
469 mask = sbi->options.fs_fmask;
470 else
471 mask = sbi->options.fs_dmask;
472
473 perm = *mode_ptr & ~(S_IFMT | mask);
474
475 /*
476 * Of the r and x bits, all (subject to umask) must be present. Of the
477 * w bits, either all (subject to umask) or none must be present.
478 *
479 * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
480 */
481 if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
482 return -EPERM;
483 if (fat_mode_can_hold_ro(inode)) {
484 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
485 return -EPERM;
486 } else {
487 if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
488 return -EPERM;
489 }
490
491 *mode_ptr &= S_IFMT | perm;
492
493 return 0;
494}
495
496static int fat_allow_set_time(const struct mnt_idmap *idmap,
497 struct msdos_sb_info *sbi, struct inode *inode)
498{
499 umode_t allow_utime = sbi->options.allow_utime;
500
501 if (!vfsuid_eq_kuid(i_uid_into_vfsuid(idmap, inode),
502 current_fsuid())) {
503 if (vfsgid_in_group_p(i_gid_into_vfsgid(idmap, inode)))
504 allow_utime >>= 3;
505 if (allow_utime & MAY_WRITE)
506 return 1;
507 }
508
509 /* use a default check */
510 return 0;
511}
512
513#define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
514/* valid file mode bits */
515#define FAT_VALID_MODE (S_IFREG | S_IFDIR | S_IRWXUGO)
516
517int fat_setattr(const struct mnt_idmap *idmap, struct dentry *dentry,
518 struct iattr *attr)
519{
520 struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
521 struct inode *inode = d_inode(dentry);
522 unsigned int ia_valid;
523 int error;
524
525 /* Check for setting the inode time. */
526 ia_valid = attr->ia_valid;
527 if (ia_valid & TIMES_SET_FLAGS) {
528 if (fat_allow_set_time(idmap, sbi, inode))
529 attr->ia_valid &= ~TIMES_SET_FLAGS;
530 }
531
532 error = setattr_prepare(idmap, dentry, attr);
533 attr->ia_valid = ia_valid;
534 if (error) {
535 if (sbi->options.quiet)
536 error = 0;
537 goto out;
538 }
539
540 /*
541 * Expand the file. Since inode_setattr() updates ->i_size
542 * before calling the ->truncate(), but FAT needs to fill the
543 * hole before it. XXX: this is no longer true with new truncate
544 * sequence.
545 */
546 if (attr->ia_valid & ATTR_SIZE) {
547 inode_dio_wait(inode);
548
549 if (attr->ia_size > inode->i_size) {
550 error = fat_cont_expand(inode, attr->ia_size);
551 if (error || attr->ia_valid == ATTR_SIZE)
552 goto out;
553 attr->ia_valid &= ~ATTR_SIZE;
554 }
555 }
556
557 if (((attr->ia_valid & ATTR_UID) &&
558 (!uid_eq(from_vfsuid(idmap, i_user_ns(inode), attr->ia_vfsuid),
559 sbi->options.fs_uid))) ||
560 ((attr->ia_valid & ATTR_GID) &&
561 (!gid_eq(from_vfsgid(idmap, i_user_ns(inode), attr->ia_vfsgid),
562 sbi->options.fs_gid))) ||
563 ((attr->ia_valid & ATTR_MODE) &&
564 (attr->ia_mode & ~FAT_VALID_MODE)))
565 error = -EPERM;
566
567 if (error) {
568 if (sbi->options.quiet)
569 error = 0;
570 goto out;
571 }
572
573 /*
574 * We don't return -EPERM here. Yes, strange, but this is too
575 * old behavior.
576 */
577 if (attr->ia_valid & ATTR_MODE) {
578 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
579 attr->ia_valid &= ~ATTR_MODE;
580 }
581
582 if (attr->ia_valid & ATTR_SIZE) {
583 error = fat_block_truncate_page(inode, attr->ia_size);
584 if (error)
585 goto out;
586 down_write(&MSDOS_I(inode)->truncate_lock);
587 truncate_setsize(inode, attr->ia_size);
588 fat_truncate_blocks(inode, attr->ia_size);
589 up_write(&MSDOS_I(inode)->truncate_lock);
590 }
591
592 /*
593 * setattr_copy can't truncate these appropriately, so we'll copy them
594 * ourselves. See fat_truncate_time for the c/mtime logic on fat.
595 */
596 if (attr->ia_valid & ATTR_ATIME)
597 fat_truncate_time(inode, &attr->ia_atime, FAT_UPDATE_ATIME);
598 if (attr->ia_valid & ATTR_MTIME)
599 fat_truncate_time(inode, &attr->ia_mtime, FAT_UPDATE_CMTIME);
600 attr->ia_valid &= ~(ATTR_ATIME|ATTR_CTIME|ATTR_MTIME);
601
602 setattr_copy(idmap, inode, attr);
603 mark_inode_dirty(inode);
604out:
605 return error;
606}
607EXPORT_SYMBOL_GPL(fat_setattr);
608
609const struct inode_operations fat_file_inode_operations = {
610 .setattr = fat_setattr,
611 .getattr = fat_getattr,
612 .fileattr_get = fat_fileattr_get,
613 .update_time = fat_update_time,
614};