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