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