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 long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 118 { 119 struct inode *inode = file_inode(filp); 120 u32 __user *user_attr = (u32 __user *)arg; 121 122 switch (cmd) { 123 case FAT_IOCTL_GET_ATTRIBUTES: 124 return fat_ioctl_get_attributes(inode, user_attr); 125 case FAT_IOCTL_SET_ATTRIBUTES: 126 return fat_ioctl_set_attributes(filp, user_attr); 127 default: 128 return -ENOTTY; /* Inappropriate ioctl for device */ 129 } 130 } 131 132 #ifdef CONFIG_COMPAT 133 static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd, 134 unsigned long arg) 135 136 { 137 return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg)); 138 } 139 #endif 140 141 static int fat_file_release(struct inode *inode, struct file *filp) 142 { 143 if ((filp->f_mode & FMODE_WRITE) && 144 MSDOS_SB(inode->i_sb)->options.flush) { 145 fat_flush_inodes(inode->i_sb, inode, NULL); 146 congestion_wait(BLK_RW_ASYNC, HZ/10); 147 } 148 return 0; 149 } 150 151 int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync) 152 { 153 struct inode *inode = filp->f_mapping->host; 154 int res, err; 155 156 res = generic_file_fsync(filp, start, end, datasync); 157 err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping); 158 159 return res ? res : err; 160 } 161 162 163 const struct file_operations fat_file_operations = { 164 .llseek = generic_file_llseek, 165 .read = do_sync_read, 166 .write = do_sync_write, 167 .aio_read = generic_file_aio_read, 168 .aio_write = generic_file_aio_write, 169 .mmap = generic_file_mmap, 170 .release = fat_file_release, 171 .unlocked_ioctl = fat_generic_ioctl, 172 #ifdef CONFIG_COMPAT 173 .compat_ioctl = fat_generic_compat_ioctl, 174 #endif 175 .fsync = fat_file_fsync, 176 .splice_read = generic_file_splice_read, 177 }; 178 179 static int fat_cont_expand(struct inode *inode, loff_t size) 180 { 181 struct address_space *mapping = inode->i_mapping; 182 loff_t start = inode->i_size, count = size - inode->i_size; 183 int err; 184 185 err = generic_cont_expand_simple(inode, size); 186 if (err) 187 goto out; 188 189 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; 190 mark_inode_dirty(inode); 191 if (IS_SYNC(inode)) { 192 int err2; 193 194 /* 195 * Opencode syncing since we don't have a file open to use 196 * standard fsync path. 197 */ 198 err = filemap_fdatawrite_range(mapping, start, 199 start + count - 1); 200 err2 = sync_mapping_buffers(mapping); 201 if (!err) 202 err = err2; 203 err2 = write_inode_now(inode, 1); 204 if (!err) 205 err = err2; 206 if (!err) { 207 err = filemap_fdatawait_range(mapping, start, 208 start + count - 1); 209 } 210 } 211 out: 212 return err; 213 } 214 215 /* Free all clusters after the skip'th cluster. */ 216 static int fat_free(struct inode *inode, int skip) 217 { 218 struct super_block *sb = inode->i_sb; 219 int err, wait, free_start, i_start, i_logstart; 220 221 if (MSDOS_I(inode)->i_start == 0) 222 return 0; 223 224 fat_cache_inval_inode(inode); 225 226 wait = IS_DIRSYNC(inode); 227 i_start = free_start = MSDOS_I(inode)->i_start; 228 i_logstart = MSDOS_I(inode)->i_logstart; 229 230 /* First, we write the new file size. */ 231 if (!skip) { 232 MSDOS_I(inode)->i_start = 0; 233 MSDOS_I(inode)->i_logstart = 0; 234 } 235 MSDOS_I(inode)->i_attrs |= ATTR_ARCH; 236 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; 237 if (wait) { 238 err = fat_sync_inode(inode); 239 if (err) { 240 MSDOS_I(inode)->i_start = i_start; 241 MSDOS_I(inode)->i_logstart = i_logstart; 242 return err; 243 } 244 } else 245 mark_inode_dirty(inode); 246 247 /* Write a new EOF, and get the remaining cluster chain for freeing. */ 248 if (skip) { 249 struct fat_entry fatent; 250 int ret, fclus, dclus; 251 252 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus); 253 if (ret < 0) 254 return ret; 255 else if (ret == FAT_ENT_EOF) 256 return 0; 257 258 fatent_init(&fatent); 259 ret = fat_ent_read(inode, &fatent, dclus); 260 if (ret == FAT_ENT_EOF) { 261 fatent_brelse(&fatent); 262 return 0; 263 } else if (ret == FAT_ENT_FREE) { 264 fat_fs_error(sb, 265 "%s: invalid cluster chain (i_pos %lld)", 266 __func__, MSDOS_I(inode)->i_pos); 267 ret = -EIO; 268 } else if (ret > 0) { 269 err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait); 270 if (err) 271 ret = err; 272 } 273 fatent_brelse(&fatent); 274 if (ret < 0) 275 return ret; 276 277 free_start = ret; 278 } 279 inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9); 280 281 /* Freeing the remained cluster chain */ 282 return fat_free_clusters(inode, free_start); 283 } 284 285 void fat_truncate_blocks(struct inode *inode, loff_t offset) 286 { 287 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 288 const unsigned int cluster_size = sbi->cluster_size; 289 int nr_clusters; 290 291 /* 292 * This protects against truncating a file bigger than it was then 293 * trying to write into the hole. 294 */ 295 if (MSDOS_I(inode)->mmu_private > offset) 296 MSDOS_I(inode)->mmu_private = offset; 297 298 nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits; 299 300 fat_free(inode, nr_clusters); 301 fat_flush_inodes(inode->i_sb, inode, NULL); 302 } 303 304 int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) 305 { 306 struct inode *inode = dentry->d_inode; 307 generic_fillattr(inode, stat); 308 stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size; 309 310 if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) { 311 /* Use i_pos for ino. This is used as fileid of nfs. */ 312 stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode); 313 } 314 return 0; 315 } 316 EXPORT_SYMBOL_GPL(fat_getattr); 317 318 static int fat_sanitize_mode(const struct msdos_sb_info *sbi, 319 struct inode *inode, umode_t *mode_ptr) 320 { 321 umode_t mask, perm; 322 323 /* 324 * Note, the basic check is already done by a caller of 325 * (attr->ia_mode & ~FAT_VALID_MODE) 326 */ 327 328 if (S_ISREG(inode->i_mode)) 329 mask = sbi->options.fs_fmask; 330 else 331 mask = sbi->options.fs_dmask; 332 333 perm = *mode_ptr & ~(S_IFMT | mask); 334 335 /* 336 * Of the r and x bits, all (subject to umask) must be present. Of the 337 * w bits, either all (subject to umask) or none must be present. 338 * 339 * If fat_mode_can_hold_ro(inode) is false, can't change w bits. 340 */ 341 if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO))) 342 return -EPERM; 343 if (fat_mode_can_hold_ro(inode)) { 344 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask))) 345 return -EPERM; 346 } else { 347 if ((perm & S_IWUGO) != (S_IWUGO & ~mask)) 348 return -EPERM; 349 } 350 351 *mode_ptr &= S_IFMT | perm; 352 353 return 0; 354 } 355 356 static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode) 357 { 358 umode_t allow_utime = sbi->options.allow_utime; 359 360 if (!uid_eq(current_fsuid(), inode->i_uid)) { 361 if (in_group_p(inode->i_gid)) 362 allow_utime >>= 3; 363 if (allow_utime & MAY_WRITE) 364 return 1; 365 } 366 367 /* use a default check */ 368 return 0; 369 } 370 371 #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET) 372 /* valid file mode bits */ 373 #define FAT_VALID_MODE (S_IFREG | S_IFDIR | S_IRWXUGO) 374 375 int fat_setattr(struct dentry *dentry, struct iattr *attr) 376 { 377 struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb); 378 struct inode *inode = dentry->d_inode; 379 unsigned int ia_valid; 380 int error; 381 382 /* Check for setting the inode time. */ 383 ia_valid = attr->ia_valid; 384 if (ia_valid & TIMES_SET_FLAGS) { 385 if (fat_allow_set_time(sbi, inode)) 386 attr->ia_valid &= ~TIMES_SET_FLAGS; 387 } 388 389 error = inode_change_ok(inode, attr); 390 attr->ia_valid = ia_valid; 391 if (error) { 392 if (sbi->options.quiet) 393 error = 0; 394 goto out; 395 } 396 397 /* 398 * Expand the file. Since inode_setattr() updates ->i_size 399 * before calling the ->truncate(), but FAT needs to fill the 400 * hole before it. XXX: this is no longer true with new truncate 401 * sequence. 402 */ 403 if (attr->ia_valid & ATTR_SIZE) { 404 inode_dio_wait(inode); 405 406 if (attr->ia_size > inode->i_size) { 407 error = fat_cont_expand(inode, attr->ia_size); 408 if (error || attr->ia_valid == ATTR_SIZE) 409 goto out; 410 attr->ia_valid &= ~ATTR_SIZE; 411 } 412 } 413 414 if (((attr->ia_valid & ATTR_UID) && 415 (!uid_eq(attr->ia_uid, sbi->options.fs_uid))) || 416 ((attr->ia_valid & ATTR_GID) && 417 (!gid_eq(attr->ia_gid, sbi->options.fs_gid))) || 418 ((attr->ia_valid & ATTR_MODE) && 419 (attr->ia_mode & ~FAT_VALID_MODE))) 420 error = -EPERM; 421 422 if (error) { 423 if (sbi->options.quiet) 424 error = 0; 425 goto out; 426 } 427 428 /* 429 * We don't return -EPERM here. Yes, strange, but this is too 430 * old behavior. 431 */ 432 if (attr->ia_valid & ATTR_MODE) { 433 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0) 434 attr->ia_valid &= ~ATTR_MODE; 435 } 436 437 if (attr->ia_valid & ATTR_SIZE) { 438 down_write(&MSDOS_I(inode)->truncate_lock); 439 truncate_setsize(inode, attr->ia_size); 440 fat_truncate_blocks(inode, attr->ia_size); 441 up_write(&MSDOS_I(inode)->truncate_lock); 442 } 443 444 setattr_copy(inode, attr); 445 mark_inode_dirty(inode); 446 out: 447 return error; 448 } 449 EXPORT_SYMBOL_GPL(fat_setattr); 450 451 const struct inode_operations fat_file_inode_operations = { 452 .setattr = fat_setattr, 453 .getattr = fat_getattr, 454 }; 455