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/fsnotify.h>
  15 #include <linux/security.h>
  16 #include "fat.h"
  17
  18 static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
  19 {
  20         u32 attr;
  21
  22         mutex_lock(&inode->i_mutex);
  23         attr = fat_make_attrs(inode);
  24         mutex_unlock(&inode->i_mutex);
  25
  26         return put_user(attr, user_attr);
  27 }
  28
  29 static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
  30 {
  31         struct inode *inode = file_inode(file);
  32         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
  33         int is_dir = S_ISDIR(inode->i_mode);
  34         u32 attr, oldattr;
  35         struct iattr ia;
  36         int err;
  37
  38         err = get_user(attr, user_attr);
  39         if (err)
  40                 goto out;
  41
  42         err = mnt_want_write_file(file);
  43         if (err)
  44                 goto out;
  45         mutex_lock(&inode->i_mutex);
  46
  47         /*
  48          * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
  49          * prevents the user from turning us into a VFAT
  50          * longname entry.  Also, we obviously can't set
  51          * any of the NTFS attributes in the high 24 bits.
  52          */
  53         attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);
  54         /* Merge in ATTR_VOLUME and ATTR_DIR */
  55         attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
  56                 (is_dir ? ATTR_DIR : 0);
  57         oldattr = fat_make_attrs(inode);
  58
  59         /* Equivalent to a chmod() */
  60         ia.ia_valid = ATTR_MODE | ATTR_CTIME;
  61         ia.ia_ctime = current_fs_time(inode->i_sb);
  62         if (is_dir)
  63                 ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
  64         else {
  65                 ia.ia_mode = fat_make_mode(sbi, attr,
  66                         S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));
  67         }
  68
  69         /* The root directory has no attributes */
  70         if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
  71                 err = -EINVAL;
  72                 goto out_unlock_inode;
  73         }
  74
  75         if (sbi->options.sys_immutable &&
  76             ((attr | oldattr) & ATTR_SYS) &&
  77             !capable(CAP_LINUX_IMMUTABLE)) {
  78                 err = -EPERM;
  79                 goto out_unlock_inode;
  80         }
  81
  82         /*
  83          * The security check is questionable...  We single
  84          * out the RO attribute for checking by the security
  85          * module, just because it maps to a file mode.
  86          */
  87         err = security_inode_setattr(file->f_path.dentry, &ia);
  88         if (err)
  89                 goto out_unlock_inode;
  90
  91         /* This MUST be done before doing anything irreversible... */
  92         err = fat_setattr(file->f_path.dentry, &ia);
  93         if (err)
  94                 goto out_unlock_inode;
  95
  96         fsnotify_change(file->f_path.dentry, ia.ia_valid);
  97         if (sbi->options.sys_immutable) {
  98                 if (attr & ATTR_SYS)
  99                         inode->i_flags |= S_IMMUTABLE;
 100                 else
 101                         inode->i_flags &= ~S_IMMUTABLE;
 102         }
 103
 104         fat_save_attrs(inode, attr);
 105         mark_inode_dirty(inode);
 106 out_unlock_inode:
 107         mutex_unlock(&inode->i_mutex);
 108         mnt_drop_write_file(file);
 109 out:
 110         return err;
 111 }
 112
 113 static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)
 114 {
 115         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 116         return put_user(sbi->vol_id, user_attr);
 117 }
 118
 119 long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 120 {
 121         struct inode *inode = file_inode(filp);
 122         u32 __user *user_attr = (u32 __user *)arg;
 123
 124         switch (cmd) {
 125         case FAT_IOCTL_GET_ATTRIBUTES:
 126                 return fat_ioctl_get_attributes(inode, user_attr);
 127         case FAT_IOCTL_SET_ATTRIBUTES:
 128                 return fat_ioctl_set_attributes(filp, user_attr);
 129         case FAT_IOCTL_GET_VOLUME_ID:
 130                 return fat_ioctl_get_volume_id(inode, user_attr);
 131         default:
 132                 return -ENOTTY; /* Inappropriate ioctl for device */
 133         }
 134 }
 135
 136 #ifdef CONFIG_COMPAT
 137 static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd,
 138                                       unsigned long arg)
 139
 140 {
 141         return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 142 }
 143 #endif
 144
 145 static int fat_file_release(struct inode *inode, struct file *filp)
 146 {
 147         if ((filp->f_mode & FMODE_WRITE) &&
 148              MSDOS_SB(inode->i_sb)->options.flush) {
 149                 fat_flush_inodes(inode->i_sb, inode, NULL);
 150                 congestion_wait(BLK_RW_ASYNC, HZ/10);
 151         }
 152         return 0;
 153 }
 154
 155 int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 156 {
 157         struct inode *inode = filp->f_mapping->host;
 158         int res, err;
 159
 160         res = generic_file_fsync(filp, start, end, datasync);
 161         err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
 162
 163         return res ? res : err;
 164 }
 165
 166
 167 const struct file_operations fat_file_operations = {
 168         .llseek         = generic_file_llseek,
 169         .read_iter      = generic_file_read_iter,
 170         .write_iter     = generic_file_write_iter,
 171         .mmap           = generic_file_mmap,
 172         .release        = fat_file_release,
 173         .unlocked_ioctl = fat_generic_ioctl,
 174 #ifdef CONFIG_COMPAT
 175         .compat_ioctl   = fat_generic_compat_ioctl,
 176 #endif
 177         .fsync          = fat_file_fsync,
 178         .splice_read    = generic_file_splice_read,
 179 };
 180
 181 static int fat_cont_expand(struct inode *inode, loff_t size)
 182 {
 183         struct address_space *mapping = inode->i_mapping;
 184         loff_t start = inode->i_size, count = size - inode->i_size;
 185         int err;
 186
 187         err = generic_cont_expand_simple(inode, size);
 188         if (err)
 189                 goto out;
 190
 191         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 192         mark_inode_dirty(inode);
 193         if (IS_SYNC(inode)) {
 194                 int err2;
 195
 196                 /*
 197                  * Opencode syncing since we don't have a file open to use
 198                  * standard fsync path.
 199                  */
 200                 err = filemap_fdatawrite_range(mapping, start,
 201                                                start + count - 1);
 202                 err2 = sync_mapping_buffers(mapping);
 203                 if (!err)
 204                         err = err2;
 205                 err2 = write_inode_now(inode, 1);
 206                 if (!err)
 207                         err = err2;
 208                 if (!err) {
 209                         err =  filemap_fdatawait_range(mapping, start,
 210                                                        start + count - 1);
 211                 }
 212         }
 213 out:
 214         return err;
 215 }
 216
 217 /* Free all clusters after the skip'th cluster. */
 218 static int fat_free(struct inode *inode, int skip)
 219 {
 220         struct super_block *sb = inode->i_sb;
 221         int err, wait, free_start, i_start, i_logstart;
 222
 223         if (MSDOS_I(inode)->i_start == 0)
 224                 return 0;
 225
 226         fat_cache_inval_inode(inode);
 227
 228         wait = IS_DIRSYNC(inode);
 229         i_start = free_start = MSDOS_I(inode)->i_start;
 230         i_logstart = MSDOS_I(inode)->i_logstart;
 231
 232         /* First, we write the new file size. */
 233         if (!skip) {
 234                 MSDOS_I(inode)->i_start = 0;
 235                 MSDOS_I(inode)->i_logstart = 0;
 236         }
 237         MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 238         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 239         if (wait) {
 240                 err = fat_sync_inode(inode);
 241                 if (err) {
 242                         MSDOS_I(inode)->i_start = i_start;
 243                         MSDOS_I(inode)->i_logstart = i_logstart;
 244                         return err;
 245                 }
 246         } else
 247                 mark_inode_dirty(inode);
 248
 249         /* Write a new EOF, and get the remaining cluster chain for freeing. */
 250         if (skip) {
 251                 struct fat_entry fatent;
 252                 int ret, fclus, dclus;
 253
 254                 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
 255                 if (ret < 0)
 256                         return ret;
 257                 else if (ret == FAT_ENT_EOF)
 258                         return 0;
 259
 260                 fatent_init(&fatent);
 261                 ret = fat_ent_read(inode, &fatent, dclus);
 262                 if (ret == FAT_ENT_EOF) {
 263                         fatent_brelse(&fatent);
 264                         return 0;
 265                 } else if (ret == FAT_ENT_FREE) {
 266                         fat_fs_error(sb,
 267                                      "%s: invalid cluster chain (i_pos %lld)",
 268                                      __func__, MSDOS_I(inode)->i_pos);
 269                         ret = -EIO;
 270                 } else if (ret > 0) {
 271                         err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
 272                         if (err)
 273                                 ret = err;
 274                 }
 275                 fatent_brelse(&fatent);
 276                 if (ret < 0)
 277                         return ret;
 278
 279                 free_start = ret;
 280         }
 281         inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
 282
 283         /* Freeing the remained cluster chain */
 284         return fat_free_clusters(inode, free_start);
 285 }
 286
 287 void fat_truncate_blocks(struct inode *inode, loff_t offset)
 288 {
 289         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 290         const unsigned int cluster_size = sbi->cluster_size;
 291         int nr_clusters;
 292
 293         /*
 294          * This protects against truncating a file bigger than it was then
 295          * trying to write into the hole.
 296          */
 297         if (MSDOS_I(inode)->mmu_private > offset)
 298                 MSDOS_I(inode)->mmu_private = offset;
 299
 300         nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
 301
 302         fat_free(inode, nr_clusters);
 303         fat_flush_inodes(inode->i_sb, inode, NULL);
 304 }
 305
 306 int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 307 {
 308         struct inode *inode = dentry->d_inode;
 309         generic_fillattr(inode, stat);
 310         stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
 311
 312         if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
 313                 /* Use i_pos for ino. This is used as fileid of nfs. */
 314                 stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
 315         }
 316         return 0;
 317 }
 318 EXPORT_SYMBOL_GPL(fat_getattr);
 319
 320 static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
 321                              struct inode *inode, umode_t *mode_ptr)
 322 {
 323         umode_t mask, perm;
 324
 325         /*
 326          * Note, the basic check is already done by a caller of
 327          * (attr->ia_mode & ~FAT_VALID_MODE)
 328          */
 329
 330         if (S_ISREG(inode->i_mode))
 331                 mask = sbi->options.fs_fmask;
 332         else
 333                 mask = sbi->options.fs_dmask;
 334
 335         perm = *mode_ptr & ~(S_IFMT | mask);
 336
 337         /*
 338          * Of the r and x bits, all (subject to umask) must be present. Of the
 339          * w bits, either all (subject to umask) or none must be present.
 340          *
 341          * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
 342          */
 343         if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
 344                 return -EPERM;
 345         if (fat_mode_can_hold_ro(inode)) {
 346                 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
 347                         return -EPERM;
 348         } else {
 349                 if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
 350                         return -EPERM;
 351         }
 352
 353         *mode_ptr &= S_IFMT | perm;
 354
 355         return 0;
 356 }
 357
 358 static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
 359 {
 360         umode_t allow_utime = sbi->options.allow_utime;
 361
 362         if (!uid_eq(current_fsuid(), inode->i_uid)) {
 363                 if (in_group_p(inode->i_gid))
 364                         allow_utime >>= 3;
 365                 if (allow_utime & MAY_WRITE)
 366                         return 1;
 367         }
 368
 369         /* use a default check */
 370         return 0;
 371 }
 372
 373 #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
 374 /* valid file mode bits */
 375 #define FAT_VALID_MODE  (S_IFREG | S_IFDIR | S_IRWXUGO)
 376
 377 int fat_setattr(struct dentry *dentry, struct iattr *attr)
 378 {
 379         struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 380         struct inode *inode = dentry->d_inode;
 381         unsigned int ia_valid;
 382         int error;
 383
 384         /* Check for setting the inode time. */
 385         ia_valid = attr->ia_valid;
 386         if (ia_valid & TIMES_SET_FLAGS) {
 387                 if (fat_allow_set_time(sbi, inode))
 388                         attr->ia_valid &= ~TIMES_SET_FLAGS;
 389         }
 390
 391         error = inode_change_ok(inode, attr);
 392         attr->ia_valid = ia_valid;
 393         if (error) {
 394                 if (sbi->options.quiet)
 395                         error = 0;
 396                 goto out;
 397         }
 398
 399         /*
 400          * Expand the file. Since inode_setattr() updates ->i_size
 401          * before calling the ->truncate(), but FAT needs to fill the
 402          * hole before it. XXX: this is no longer true with new truncate
 403          * sequence.
 404          */
 405         if (attr->ia_valid & ATTR_SIZE) {
 406                 inode_dio_wait(inode);
 407
 408                 if (attr->ia_size > inode->i_size) {
 409                         error = fat_cont_expand(inode, attr->ia_size);
 410                         if (error || attr->ia_valid == ATTR_SIZE)
 411                                 goto out;
 412                         attr->ia_valid &= ~ATTR_SIZE;
 413                 }
 414         }
 415
 416         if (((attr->ia_valid & ATTR_UID) &&
 417              (!uid_eq(attr->ia_uid, sbi->options.fs_uid))) ||
 418             ((attr->ia_valid & ATTR_GID) &&
 419              (!gid_eq(attr->ia_gid, sbi->options.fs_gid))) ||
 420             ((attr->ia_valid & ATTR_MODE) &&
 421              (attr->ia_mode & ~FAT_VALID_MODE)))
 422                 error = -EPERM;
 423
 424         if (error) {
 425                 if (sbi->options.quiet)
 426                         error = 0;
 427                 goto out;
 428         }
 429
 430         /*
 431          * We don't return -EPERM here. Yes, strange, but this is too
 432          * old behavior.
 433          */
 434         if (attr->ia_valid & ATTR_MODE) {
 435                 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
 436                         attr->ia_valid &= ~ATTR_MODE;
 437         }
 438
 439         if (attr->ia_valid & ATTR_SIZE) {
 440                 error = fat_block_truncate_page(inode, attr->ia_size);
 441                 if (error)
 442                         goto out;
 443                 down_write(&MSDOS_I(inode)->truncate_lock);
 444                 truncate_setsize(inode, attr->ia_size);
 445                 fat_truncate_blocks(inode, attr->ia_size);
 446                 up_write(&MSDOS_I(inode)->truncate_lock);
 447         }
 448
 449         setattr_copy(inode, attr);
 450         mark_inode_dirty(inode);
 451 out:
 452         return error;
 453 }
 454 EXPORT_SYMBOL_GPL(fat_setattr);
 455
 456 const struct inode_operations fat_file_inode_operations = {
 457         .setattr        = fat_setattr,
 458         .getattr        = fat_getattr,
 459 };