fs/fat/file.c

   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 static int fat_ioctl_fitrim(struct inode *inode, unsigned long arg)
 125 {
 126         struct super_block *sb = inode->i_sb;
 127         struct fstrim_range __user *user_range;
 128         struct fstrim_range range;
 129         struct request_queue *q = bdev_get_queue(sb->s_bdev);
 130         int err;
 131
 132         if (!capable(CAP_SYS_ADMIN))
 133                 return -EPERM;
 134
 135         if (!blk_queue_discard(q))
 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                              q->limits.discard_granularity);
 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 #ifdef CONFIG_COMPAT
 175 static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd,
 176                                       unsigned long arg)
 177
 178 {
 179         return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 180 }
 181 #endif
 182
 183 static int fat_file_release(struct inode *inode, struct file *filp)
 184 {
 185         if ((filp->f_mode & FMODE_WRITE) &&
 186              MSDOS_SB(inode->i_sb)->options.flush) {
 187                 fat_flush_inodes(inode->i_sb, inode, NULL);
 188                 congestion_wait(BLK_RW_ASYNC, HZ/10);
 189         }
 190         return 0;
 191 }
 192
 193 int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 194 {
 195         struct inode *inode = filp->f_mapping->host;
 196         int res, err;
 197
 198         res = generic_file_fsync(filp, start, end, datasync);
 199         err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
 200
 201         return res ? res : err;
 202 }
 203
 204
 205 const struct file_operations fat_file_operations = {
 206         .llseek         = generic_file_llseek,
 207         .read_iter      = generic_file_read_iter,
 208         .write_iter     = generic_file_write_iter,
 209         .mmap           = generic_file_mmap,
 210         .release        = fat_file_release,
 211         .unlocked_ioctl = fat_generic_ioctl,
 212 #ifdef CONFIG_COMPAT
 213         .compat_ioctl   = fat_generic_compat_ioctl,
 214 #endif
 215         .fsync          = fat_file_fsync,
 216         .splice_read    = generic_file_splice_read,
 217         .splice_write   = iter_file_splice_write,
 218         .fallocate      = fat_fallocate,
 219 };
 220
 221 static int fat_cont_expand(struct inode *inode, loff_t size)
 222 {
 223         struct address_space *mapping = inode->i_mapping;
 224         loff_t start = inode->i_size, count = size - inode->i_size;
 225         int err;
 226
 227         err = generic_cont_expand_simple(inode, size);
 228         if (err)
 229                 goto out;
 230
 231         fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
 232         mark_inode_dirty(inode);
 233         if (IS_SYNC(inode)) {
 234                 int err2;
 235
 236                 /*
 237                  * Opencode syncing since we don't have a file open to use
 238                  * standard fsync path.
 239                  */
 240                 err = filemap_fdatawrite_range(mapping, start,
 241                                                start + count - 1);
 242                 err2 = sync_mapping_buffers(mapping);
 243                 if (!err)
 244                         err = err2;
 245                 err2 = write_inode_now(inode, 1);
 246                 if (!err)
 247                         err = err2;
 248                 if (!err) {
 249                         err =  filemap_fdatawait_range(mapping, start,
 250                                                        start + count - 1);
 251                 }
 252         }
 253 out:
 254         return err;
 255 }
 256
 257 /*
 258  * Preallocate space for a file. This implements fat's fallocate file
 259  * operation, which gets called from sys_fallocate system call. User
 260  * space requests len bytes at offset. If FALLOC_FL_KEEP_SIZE is set
 261  * we just allocate clusters without zeroing them out. Otherwise we
 262  * allocate and zero out clusters via an expanding truncate.
 263  */
 264 static long fat_fallocate(struct file *file, int mode,
 265                           loff_t offset, loff_t len)
 266 {
 267         int nr_cluster; /* Number of clusters to be allocated */
 268         loff_t mm_bytes; /* Number of bytes to be allocated for file */
 269         loff_t ondisksize; /* block aligned on-disk size in bytes*/
 270         struct inode *inode = file->f_mapping->host;
 271         struct super_block *sb = inode->i_sb;
 272         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 273         int err = 0;
 274
 275         /* No support for hole punch or other fallocate flags. */
 276         if (mode & ~FALLOC_FL_KEEP_SIZE)
 277                 return -EOPNOTSUPP;
 278
 279         /* No support for dir */
 280         if (!S_ISREG(inode->i_mode))
 281                 return -EOPNOTSUPP;
 282
 283         inode_lock(inode);
 284         if (mode & FALLOC_FL_KEEP_SIZE) {
 285                 ondisksize = inode->i_blocks << 9;
 286                 if ((offset + len) <= ondisksize)
 287                         goto error;
 288
 289                 /* First compute the number of clusters to be allocated */
 290                 mm_bytes = offset + len - ondisksize;
 291                 nr_cluster = (mm_bytes + (sbi->cluster_size - 1)) >>
 292                         sbi->cluster_bits;
 293
 294                 /* Start the allocation.We are not zeroing out the clusters */
 295                 while (nr_cluster-- > 0) {
 296                         err = fat_add_cluster(inode);
 297                         if (err)
 298                                 goto error;
 299                 }
 300         } else {
 301                 if ((offset + len) <= i_size_read(inode))
 302                         goto error;
 303
 304                 /* This is just an expanding truncate */
 305                 err = fat_cont_expand(inode, (offset + len));
 306         }
 307
 308 error:
 309         inode_unlock(inode);
 310         return err;
 311 }
 312
 313 /* Free all clusters after the skip'th cluster. */
 314 static int fat_free(struct inode *inode, int skip)
 315 {
 316         struct super_block *sb = inode->i_sb;
 317         int err, wait, free_start, i_start, i_logstart;
 318
 319         if (MSDOS_I(inode)->i_start == 0)
 320                 return 0;
 321
 322         fat_cache_inval_inode(inode);
 323
 324         wait = IS_DIRSYNC(inode);
 325         i_start = free_start = MSDOS_I(inode)->i_start;
 326         i_logstart = MSDOS_I(inode)->i_logstart;
 327
 328         /* First, we write the new file size. */
 329         if (!skip) {
 330                 MSDOS_I(inode)->i_start = 0;
 331                 MSDOS_I(inode)->i_logstart = 0;
 332         }
 333         MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 334         fat_truncate_time(inode, NULL, S_CTIME|S_MTIME);
 335         if (wait) {
 336                 err = fat_sync_inode(inode);
 337                 if (err) {
 338                         MSDOS_I(inode)->i_start = i_start;
 339                         MSDOS_I(inode)->i_logstart = i_logstart;
 340                         return err;
 341                 }
 342         } else
 343                 mark_inode_dirty(inode);
 344
 345         /* Write a new EOF, and get the remaining cluster chain for freeing. */
 346         if (skip) {
 347                 struct fat_entry fatent;
 348                 int ret, fclus, dclus;
 349
 350                 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
 351                 if (ret < 0)
 352                         return ret;
 353                 else if (ret == FAT_ENT_EOF)
 354                         return 0;
 355
 356                 fatent_init(&fatent);
 357                 ret = fat_ent_read(inode, &fatent, dclus);
 358                 if (ret == FAT_ENT_EOF) {
 359                         fatent_brelse(&fatent);
 360                         return 0;
 361                 } else if (ret == FAT_ENT_FREE) {
 362                         fat_fs_error(sb,
 363                                      "%s: invalid cluster chain (i_pos %lld)",
 364                                      __func__, MSDOS_I(inode)->i_pos);
 365                         ret = -EIO;
 366                 } else if (ret > 0) {
 367                         err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
 368                         if (err)
 369                                 ret = err;
 370                 }
 371                 fatent_brelse(&fatent);
 372                 if (ret < 0)
 373                         return ret;
 374
 375                 free_start = ret;
 376         }
 377         inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
 378
 379         /* Freeing the remained cluster chain */
 380         return fat_free_clusters(inode, free_start);
 381 }
 382
 383 void fat_truncate_blocks(struct inode *inode, loff_t offset)
 384 {
 385         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 386         const unsigned int cluster_size = sbi->cluster_size;
 387         int nr_clusters;
 388
 389         /*
 390          * This protects against truncating a file bigger than it was then
 391          * trying to write into the hole.
 392          */
 393         if (MSDOS_I(inode)->mmu_private > offset)
 394                 MSDOS_I(inode)->mmu_private = offset;
 395
 396         nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
 397
 398         fat_free(inode, nr_clusters);
 399         fat_flush_inodes(inode->i_sb, inode, NULL);
 400 }
 401
 402 int fat_getattr(const struct path *path, struct kstat *stat,
 403                 u32 request_mask, unsigned int flags)
 404 {
 405         struct inode *inode = d_inode(path->dentry);
 406         generic_fillattr(inode, stat);
 407         stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
 408
 409         if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
 410                 /* Use i_pos for ino. This is used as fileid of nfs. */
 411                 stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
 412         }
 413         return 0;
 414 }
 415 EXPORT_SYMBOL_GPL(fat_getattr);
 416
 417 static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
 418                              struct inode *inode, umode_t *mode_ptr)
 419 {
 420         umode_t mask, perm;
 421
 422         /*
 423          * Note, the basic check is already done by a caller of
 424          * (attr->ia_mode & ~FAT_VALID_MODE)
 425          */
 426
 427         if (S_ISREG(inode->i_mode))
 428                 mask = sbi->options.fs_fmask;
 429         else
 430                 mask = sbi->options.fs_dmask;
 431
 432         perm = *mode_ptr & ~(S_IFMT | mask);
 433
 434         /*
 435          * Of the r and x bits, all (subject to umask) must be present. Of the
 436          * w bits, either all (subject to umask) or none must be present.
 437          *
 438          * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
 439          */
 440         if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
 441                 return -EPERM;
 442         if (fat_mode_can_hold_ro(inode)) {
 443                 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
 444                         return -EPERM;
 445         } else {
 446                 if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
 447                         return -EPERM;
 448         }
 449
 450         *mode_ptr &= S_IFMT | perm;
 451
 452         return 0;
 453 }
 454
 455 static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
 456 {
 457         umode_t allow_utime = sbi->options.allow_utime;
 458
 459         if (!uid_eq(current_fsuid(), inode->i_uid)) {
 460                 if (in_group_p(inode->i_gid))
 461                         allow_utime >>= 3;
 462                 if (allow_utime & MAY_WRITE)
 463                         return 1;
 464         }
 465
 466         /* use a default check */
 467         return 0;
 468 }
 469
 470 #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
 471 /* valid file mode bits */
 472 #define FAT_VALID_MODE  (S_IFREG | S_IFDIR | S_IRWXUGO)
 473
 474 int fat_setattr(struct dentry *dentry, struct iattr *attr)
 475 {
 476         struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 477         struct inode *inode = d_inode(dentry);
 478         unsigned int ia_valid;
 479         int error;
 480
 481         /* Check for setting the inode time. */
 482         ia_valid = attr->ia_valid;
 483         if (ia_valid & TIMES_SET_FLAGS) {
 484                 if (fat_allow_set_time(sbi, inode))
 485                         attr->ia_valid &= ~TIMES_SET_FLAGS;
 486         }
 487
 488         error = setattr_prepare(dentry, attr);
 489         attr->ia_valid = ia_valid;
 490         if (error) {
 491                 if (sbi->options.quiet)
 492                         error = 0;
 493                 goto out;
 494         }
 495
 496         /*
 497          * Expand the file. Since inode_setattr() updates ->i_size
 498          * before calling the ->truncate(), but FAT needs to fill the
 499          * hole before it. XXX: this is no longer true with new truncate
 500          * sequence.
 501          */
 502         if (attr->ia_valid & ATTR_SIZE) {
 503                 inode_dio_wait(inode);
 504
 505                 if (attr->ia_size > inode->i_size) {
 506                         error = fat_cont_expand(inode, attr->ia_size);
 507                         if (error || attr->ia_valid == ATTR_SIZE)
 508                                 goto out;
 509                         attr->ia_valid &= ~ATTR_SIZE;
 510                 }
 511         }
 512
 513         if (((attr->ia_valid & ATTR_UID) &&
 514              (!uid_eq(attr->ia_uid, sbi->options.fs_uid))) ||
 515             ((attr->ia_valid & ATTR_GID) &&
 516              (!gid_eq(attr->ia_gid, sbi->options.fs_gid))) ||
 517             ((attr->ia_valid & ATTR_MODE) &&
 518              (attr->ia_mode & ~FAT_VALID_MODE)))
 519                 error = -EPERM;
 520
 521         if (error) {
 522                 if (sbi->options.quiet)
 523                         error = 0;
 524                 goto out;
 525         }
 526
 527         /*
 528          * We don't return -EPERM here. Yes, strange, but this is too
 529          * old behavior.
 530          */
 531         if (attr->ia_valid & ATTR_MODE) {
 532                 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
 533                         attr->ia_valid &= ~ATTR_MODE;
 534         }
 535
 536         if (attr->ia_valid & ATTR_SIZE) {
 537                 error = fat_block_truncate_page(inode, attr->ia_size);
 538                 if (error)
 539                         goto out;
 540                 down_write(&MSDOS_I(inode)->truncate_lock);
 541                 truncate_setsize(inode, attr->ia_size);
 542                 fat_truncate_blocks(inode, attr->ia_size);
 543                 up_write(&MSDOS_I(inode)->truncate_lock);
 544         }
 545
 546         /*
 547          * setattr_copy can't truncate these appropriately, so we'll
 548          * copy them ourselves
 549          */
 550         if (attr->ia_valid & ATTR_ATIME)
 551                 fat_truncate_time(inode, &attr->ia_atime, S_ATIME);
 552         if (attr->ia_valid & ATTR_CTIME)
 553                 fat_truncate_time(inode, &attr->ia_ctime, S_CTIME);
 554         if (attr->ia_valid & ATTR_MTIME)
 555                 fat_truncate_time(inode, &attr->ia_mtime, S_MTIME);
 556         attr->ia_valid &= ~(ATTR_ATIME|ATTR_CTIME|ATTR_MTIME);
 557
 558         setattr_copy(inode, attr);
 559         mark_inode_dirty(inode);
 560 out:
 561         return error;
 562 }
 563 EXPORT_SYMBOL_GPL(fat_setattr);
 564
 565 const struct inode_operations fat_file_inode_operations = {
 566         .setattr        = fat_setattr,
 567         .getattr        = fat_getattr,
 568         .update_time    = fat_update_time,
 569 };