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->f_path.dentry->d_inode; 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 mutex_lock(&inode->i_mutex); 47 err = mnt_want_write_file(file); 48 if (err) 49 goto out_unlock_inode; 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_drop_write; 77 } 78 79 if (sbi->options.sys_immutable && 80 ((attr | oldattr) & ATTR_SYS) && 81 !capable(CAP_LINUX_IMMUTABLE)) { 82 err = -EPERM; 83 goto out_drop_write; 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_drop_write; 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_drop_write; 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_drop_write: 111 mnt_drop_write_file(file); 112 out_unlock_inode: 113 mutex_unlock(&inode->i_mutex); 114 out: 115 return err; 116 } 117 118 long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) 119 { 120 struct inode *inode = filp->f_path.dentry->d_inode; 121 u32 __user *user_attr = (u32 __user *)arg; 122 123 switch (cmd) { 124 case FAT_IOCTL_GET_ATTRIBUTES: 125 return fat_ioctl_get_attributes(inode, user_attr); 126 case FAT_IOCTL_SET_ATTRIBUTES: 127 return fat_ioctl_set_attributes(filp, user_attr); 128 default: 129 return -ENOTTY; /* Inappropriate ioctl for device */ 130 } 131 } 132 133 #ifdef CONFIG_COMPAT 134 static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd, 135 unsigned long arg) 136 137 { 138 return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg)); 139 } 140 #endif 141 142 static int fat_file_release(struct inode *inode, struct file *filp) 143 { 144 if ((filp->f_mode & FMODE_WRITE) && 145 MSDOS_SB(inode->i_sb)->options.flush) { 146 fat_flush_inodes(inode->i_sb, inode, NULL); 147 congestion_wait(BLK_RW_ASYNC, HZ/10); 148 } 149 return 0; 150 } 151 152 int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync) 153 { 154 struct inode *inode = filp->f_mapping->host; 155 int res, err; 156 157 res = generic_file_fsync(filp, start, end, datasync); 158 err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping); 159 160 return res ? res : err; 161 } 162 163 164 const struct file_operations fat_file_operations = { 165 .llseek = generic_file_llseek, 166 .read = do_sync_read, 167 .write = do_sync_write, 168 .aio_read = generic_file_aio_read, 169 .aio_write = generic_file_aio_write, 170 .mmap = generic_file_mmap, 171 .release = fat_file_release, 172 .unlocked_ioctl = fat_generic_ioctl, 173 #ifdef CONFIG_COMPAT 174 .compat_ioctl = fat_generic_compat_ioctl, 175 #endif 176 .fsync = fat_file_fsync, 177 .splice_read = generic_file_splice_read, 178 }; 179 180 static int fat_cont_expand(struct inode *inode, loff_t size) 181 { 182 struct address_space *mapping = inode->i_mapping; 183 loff_t start = inode->i_size, count = size - inode->i_size; 184 int err; 185 186 err = generic_cont_expand_simple(inode, size); 187 if (err) 188 goto out; 189 190 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; 191 mark_inode_dirty(inode); 192 if (IS_SYNC(inode)) { 193 int err2; 194 195 /* 196 * Opencode syncing since we don't have a file open to use 197 * standard fsync path. 198 */ 199 err = filemap_fdatawrite_range(mapping, start, 200 start + count - 1); 201 err2 = sync_mapping_buffers(mapping); 202 if (!err) 203 err = err2; 204 err2 = write_inode_now(inode, 1); 205 if (!err) 206 err = err2; 207 if (!err) { 208 err = filemap_fdatawait_range(mapping, start, 209 start + count - 1); 210 } 211 } 212 out: 213 return err; 214 } 215 216 /* Free all clusters after the skip'th cluster. */ 217 static int fat_free(struct inode *inode, int skip) 218 { 219 struct super_block *sb = inode->i_sb; 220 int err, wait, free_start, i_start, i_logstart; 221 222 if (MSDOS_I(inode)->i_start == 0) 223 return 0; 224 225 fat_cache_inval_inode(inode); 226 227 wait = IS_DIRSYNC(inode); 228 i_start = free_start = MSDOS_I(inode)->i_start; 229 i_logstart = MSDOS_I(inode)->i_logstart; 230 231 /* First, we write the new file size. */ 232 if (!skip) { 233 MSDOS_I(inode)->i_start = 0; 234 MSDOS_I(inode)->i_logstart = 0; 235 } 236 MSDOS_I(inode)->i_attrs |= ATTR_ARCH; 237 inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; 238 if (wait) { 239 err = fat_sync_inode(inode); 240 if (err) { 241 MSDOS_I(inode)->i_start = i_start; 242 MSDOS_I(inode)->i_logstart = i_logstart; 243 return err; 244 } 245 } else 246 mark_inode_dirty(inode); 247 248 /* Write a new EOF, and get the remaining cluster chain for freeing. */ 249 if (skip) { 250 struct fat_entry fatent; 251 int ret, fclus, dclus; 252 253 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus); 254 if (ret < 0) 255 return ret; 256 else if (ret == FAT_ENT_EOF) 257 return 0; 258 259 fatent_init(&fatent); 260 ret = fat_ent_read(inode, &fatent, dclus); 261 if (ret == FAT_ENT_EOF) { 262 fatent_brelse(&fatent); 263 return 0; 264 } else if (ret == FAT_ENT_FREE) { 265 fat_fs_error(sb, 266 "%s: invalid cluster chain (i_pos %lld)", 267 __func__, MSDOS_I(inode)->i_pos); 268 ret = -EIO; 269 } else if (ret > 0) { 270 err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait); 271 if (err) 272 ret = err; 273 } 274 fatent_brelse(&fatent); 275 if (ret < 0) 276 return ret; 277 278 free_start = ret; 279 } 280 inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9); 281 282 /* Freeing the remained cluster chain */ 283 return fat_free_clusters(inode, free_start); 284 } 285 286 void fat_truncate_blocks(struct inode *inode, loff_t offset) 287 { 288 struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); 289 const unsigned int cluster_size = sbi->cluster_size; 290 int nr_clusters; 291 292 /* 293 * This protects against truncating a file bigger than it was then 294 * trying to write into the hole. 295 */ 296 if (MSDOS_I(inode)->mmu_private > offset) 297 MSDOS_I(inode)->mmu_private = offset; 298 299 nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits; 300 301 fat_free(inode, nr_clusters); 302 fat_flush_inodes(inode->i_sb, inode, NULL); 303 } 304 305 int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat) 306 { 307 struct inode *inode = dentry->d_inode; 308 generic_fillattr(inode, stat); 309 stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size; 310 return 0; 311 } 312 EXPORT_SYMBOL_GPL(fat_getattr); 313 314 static int fat_sanitize_mode(const struct msdos_sb_info *sbi, 315 struct inode *inode, umode_t *mode_ptr) 316 { 317 umode_t mask, perm; 318 319 /* 320 * Note, the basic check is already done by a caller of 321 * (attr->ia_mode & ~FAT_VALID_MODE) 322 */ 323 324 if (S_ISREG(inode->i_mode)) 325 mask = sbi->options.fs_fmask; 326 else 327 mask = sbi->options.fs_dmask; 328 329 perm = *mode_ptr & ~(S_IFMT | mask); 330 331 /* 332 * Of the r and x bits, all (subject to umask) must be present. Of the 333 * w bits, either all (subject to umask) or none must be present. 334 * 335 * If fat_mode_can_hold_ro(inode) is false, can't change w bits. 336 */ 337 if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO))) 338 return -EPERM; 339 if (fat_mode_can_hold_ro(inode)) { 340 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask))) 341 return -EPERM; 342 } else { 343 if ((perm & S_IWUGO) != (S_IWUGO & ~mask)) 344 return -EPERM; 345 } 346 347 *mode_ptr &= S_IFMT | perm; 348 349 return 0; 350 } 351 352 static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode) 353 { 354 umode_t allow_utime = sbi->options.allow_utime; 355 356 if (current_fsuid() != inode->i_uid) { 357 if (in_group_p(inode->i_gid)) 358 allow_utime >>= 3; 359 if (allow_utime & MAY_WRITE) 360 return 1; 361 } 362 363 /* use a default check */ 364 return 0; 365 } 366 367 #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET) 368 /* valid file mode bits */ 369 #define FAT_VALID_MODE (S_IFREG | S_IFDIR | S_IRWXUGO) 370 371 int fat_setattr(struct dentry *dentry, struct iattr *attr) 372 { 373 struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb); 374 struct inode *inode = dentry->d_inode; 375 unsigned int ia_valid; 376 int error; 377 378 /* Check for setting the inode time. */ 379 ia_valid = attr->ia_valid; 380 if (ia_valid & TIMES_SET_FLAGS) { 381 if (fat_allow_set_time(sbi, inode)) 382 attr->ia_valid &= ~TIMES_SET_FLAGS; 383 } 384 385 error = inode_change_ok(inode, attr); 386 attr->ia_valid = ia_valid; 387 if (error) { 388 if (sbi->options.quiet) 389 error = 0; 390 goto out; 391 } 392 393 /* 394 * Expand the file. Since inode_setattr() updates ->i_size 395 * before calling the ->truncate(), but FAT needs to fill the 396 * hole before it. XXX: this is no longer true with new truncate 397 * sequence. 398 */ 399 if (attr->ia_valid & ATTR_SIZE) { 400 inode_dio_wait(inode); 401 402 if (attr->ia_size > inode->i_size) { 403 error = fat_cont_expand(inode, attr->ia_size); 404 if (error || attr->ia_valid == ATTR_SIZE) 405 goto out; 406 attr->ia_valid &= ~ATTR_SIZE; 407 } 408 } 409 410 if (((attr->ia_valid & ATTR_UID) && 411 (attr->ia_uid != sbi->options.fs_uid)) || 412 ((attr->ia_valid & ATTR_GID) && 413 (attr->ia_gid != sbi->options.fs_gid)) || 414 ((attr->ia_valid & ATTR_MODE) && 415 (attr->ia_mode & ~FAT_VALID_MODE))) 416 error = -EPERM; 417 418 if (error) { 419 if (sbi->options.quiet) 420 error = 0; 421 goto out; 422 } 423 424 /* 425 * We don't return -EPERM here. Yes, strange, but this is too 426 * old behavior. 427 */ 428 if (attr->ia_valid & ATTR_MODE) { 429 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0) 430 attr->ia_valid &= ~ATTR_MODE; 431 } 432 433 if (attr->ia_valid & ATTR_SIZE) { 434 down_write(&MSDOS_I(inode)->truncate_lock); 435 truncate_setsize(inode, attr->ia_size); 436 fat_truncate_blocks(inode, attr->ia_size); 437 up_write(&MSDOS_I(inode)->truncate_lock); 438 } 439 440 setattr_copy(inode, attr); 441 mark_inode_dirty(inode); 442 out: 443 return error; 444 } 445 EXPORT_SYMBOL_GPL(fat_setattr); 446 447 const struct inode_operations fat_file_inode_operations = { 448 .setattr = fat_setattr, 449 .getattr = fat_getattr, 450 }; 451