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 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 };