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