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 "fat.h"
  18
  19 static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
  20 {
  21         u32 attr;
  22
  23         mutex_lock(&inode->i_mutex);
  24         attr = fat_make_attrs(inode);
  25         mutex_unlock(&inode->i_mutex);
  26
  27         return put_user(attr, user_attr);
  28 }
  29
  30 static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
  31 {
  32         struct inode *inode = file_inode(file);
  33         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
  34         int is_dir = S_ISDIR(inode->i_mode);
  35         u32 attr, oldattr;
  36         struct iattr ia;
  37         int err;
  38
  39         err = get_user(attr, user_attr);
  40         if (err)
  41                 goto out;
  42
  43         err = mnt_want_write_file(file);
  44         if (err)
  45                 goto out;
  46         mutex_lock(&inode->i_mutex);
  47
  48         /*
  49          * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
  50          * prevents the user from turning us into a VFAT
  51          * longname entry.  Also, we obviously can't set
  52          * any of the NTFS attributes in the high 24 bits.
  53          */
  54         attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);
  55         /* Merge in ATTR_VOLUME and ATTR_DIR */
  56         attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
  57                 (is_dir ? ATTR_DIR : 0);
  58         oldattr = fat_make_attrs(inode);
  59
  60         /* Equivalent to a chmod() */
  61         ia.ia_valid = ATTR_MODE | ATTR_CTIME;
  62         ia.ia_ctime = current_fs_time(inode->i_sb);
  63         if (is_dir)
  64                 ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
  65         else {
  66                 ia.ia_mode = fat_make_mode(sbi, attr,
  67                         S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));
  68         }
  69
  70         /* The root directory has no attributes */
  71         if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
  72                 err = -EINVAL;
  73                 goto out_unlock_inode;
  74         }
  75
  76         if (sbi->options.sys_immutable &&
  77             ((attr | oldattr) & ATTR_SYS) &&
  78             !capable(CAP_LINUX_IMMUTABLE)) {
  79                 err = -EPERM;
  80                 goto out_unlock_inode;
  81         }
  82
  83         /*
  84          * The security check is questionable...  We single
  85          * out the RO attribute for checking by the security
  86          * module, just because it maps to a file mode.
  87          */
  88         err = security_inode_setattr(file->f_path.dentry, &ia);
  89         if (err)
  90                 goto out_unlock_inode;
  91
  92         /* This MUST be done before doing anything irreversible... */
  93         err = fat_setattr(file->f_path.dentry, &ia);
  94         if (err)
  95                 goto out_unlock_inode;
  96
  97         fsnotify_change(file->f_path.dentry, ia.ia_valid);
  98         if (sbi->options.sys_immutable) {
  99                 if (attr & ATTR_SYS)
 100                         inode->i_flags |= S_IMMUTABLE;
 101                 else
 102                         inode->i_flags &= ~S_IMMUTABLE;
 103         }
 104
 105         fat_save_attrs(inode, attr);
 106         mark_inode_dirty(inode);
 107 out_unlock_inode:
 108         mutex_unlock(&inode->i_mutex);
 109         mnt_drop_write_file(file);
 110 out:
 111         return err;
 112 }
 113
 114 static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)
 115 {
 116         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 117         return put_user(sbi->vol_id, user_attr);
 118 }
 119
 120 long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 121 {
 122         struct inode *inode = file_inode(filp);
 123         u32 __user *user_attr = (u32 __user *)arg;
 124
 125         switch (cmd) {
 126         case FAT_IOCTL_GET_ATTRIBUTES:
 127                 return fat_ioctl_get_attributes(inode, user_attr);
 128         case FAT_IOCTL_SET_ATTRIBUTES:
 129                 return fat_ioctl_set_attributes(filp, user_attr);
 130         case FAT_IOCTL_GET_VOLUME_ID:
 131                 return fat_ioctl_get_volume_id(inode, user_attr);
 132         default:
 133                 return -ENOTTY; /* Inappropriate ioctl for device */
 134         }
 135 }
 136
 137 #ifdef CONFIG_COMPAT
 138 static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd,
 139                                       unsigned long arg)
 140
 141 {
 142         return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 143 }
 144 #endif
 145
 146 static int fat_file_release(struct inode *inode, struct file *filp)
 147 {
 148         if ((filp->f_mode & FMODE_WRITE) &&
 149              MSDOS_SB(inode->i_sb)->options.flush) {
 150                 fat_flush_inodes(inode->i_sb, inode, NULL);
 151                 congestion_wait(BLK_RW_ASYNC, HZ/10);
 152         }
 153         return 0;
 154 }
 155
 156 int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 157 {
 158         struct inode *inode = filp->f_mapping->host;
 159         int res, err;
 160
 161         res = generic_file_fsync(filp, start, end, datasync);
 162         err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
 163
 164         return res ? res : err;
 165 }
 166
 167
 168 const struct file_operations fat_file_operations = {
 169         .llseek         = generic_file_llseek,
 170         .read_iter      = generic_file_read_iter,
 171         .write_iter     = generic_file_write_iter,
 172         .mmap           = generic_file_mmap,
 173         .release        = fat_file_release,
 174         .unlocked_ioctl = fat_generic_ioctl,
 175 #ifdef CONFIG_COMPAT
 176         .compat_ioctl   = fat_generic_compat_ioctl,
 177 #endif
 178         .fsync          = fat_file_fsync,
 179         .splice_read    = generic_file_splice_read,
 180 };
 181
 182 static int fat_cont_expand(struct inode *inode, loff_t size)
 183 {
 184         struct address_space *mapping = inode->i_mapping;
 185         loff_t start = inode->i_size, count = size - inode->i_size;
 186         int err;
 187
 188         err = generic_cont_expand_simple(inode, size);
 189         if (err)
 190                 goto out;
 191
 192         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 193         mark_inode_dirty(inode);
 194         if (IS_SYNC(inode)) {
 195                 int err2;
 196
 197                 /*
 198                  * Opencode syncing since we don't have a file open to use
 199                  * standard fsync path.
 200                  */
 201                 err = filemap_fdatawrite_range(mapping, start,
 202                                                start + count - 1);
 203                 err2 = sync_mapping_buffers(mapping);
 204                 if (!err)
 205                         err = err2;
 206                 err2 = write_inode_now(inode, 1);
 207                 if (!err)
 208                         err = err2;
 209                 if (!err) {
 210                         err =  filemap_fdatawait_range(mapping, start,
 211                                                        start + count - 1);
 212                 }
 213         }
 214 out:
 215         return err;
 216 }
 217
 218 /* Free all clusters after the skip'th cluster. */
 219 static int fat_free(struct inode *inode, int skip)
 220 {
 221         struct super_block *sb = inode->i_sb;
 222         int err, wait, free_start, i_start, i_logstart;
 223
 224         if (MSDOS_I(inode)->i_start == 0)
 225                 return 0;
 226
 227         fat_cache_inval_inode(inode);
 228
 229         wait = IS_DIRSYNC(inode);
 230         i_start = free_start = MSDOS_I(inode)->i_start;
 231         i_logstart = MSDOS_I(inode)->i_logstart;
 232
 233         /* First, we write the new file size. */
 234         if (!skip) {
 235                 MSDOS_I(inode)->i_start = 0;
 236                 MSDOS_I(inode)->i_logstart = 0;
 237         }
 238         MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 239         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 240         if (wait) {
 241                 err = fat_sync_inode(inode);
 242                 if (err) {
 243                         MSDOS_I(inode)->i_start = i_start;
 244                         MSDOS_I(inode)->i_logstart = i_logstart;
 245                         return err;
 246                 }
 247         } else
 248                 mark_inode_dirty(inode);
 249
 250         /* Write a new EOF, and get the remaining cluster chain for freeing. */
 251         if (skip) {
 252                 struct fat_entry fatent;
 253                 int ret, fclus, dclus;
 254
 255                 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
 256                 if (ret < 0)
 257                         return ret;
 258                 else if (ret == FAT_ENT_EOF)
 259                         return 0;
 260
 261                 fatent_init(&fatent);
 262                 ret = fat_ent_read(inode, &fatent, dclus);
 263                 if (ret == FAT_ENT_EOF) {
 264                         fatent_brelse(&fatent);
 265                         return 0;
 266                 } else if (ret == FAT_ENT_FREE) {
 267                         fat_fs_error(sb,
 268                                      "%s: invalid cluster chain (i_pos %lld)",
 269                                      __func__, MSDOS_I(inode)->i_pos);
 270                         ret = -EIO;
 271                 } else if (ret > 0) {
 272                         err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
 273                         if (err)
 274                                 ret = err;
 275                 }
 276                 fatent_brelse(&fatent);
 277                 if (ret < 0)
 278                         return ret;
 279
 280                 free_start = ret;
 281         }
 282         inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
 283
 284         /* Freeing the remained cluster chain */
 285         return fat_free_clusters(inode, free_start);
 286 }
 287
 288 void fat_truncate_blocks(struct inode *inode, loff_t offset)
 289 {
 290         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 291         const unsigned int cluster_size = sbi->cluster_size;
 292         int nr_clusters;
 293
 294         /*
 295          * This protects against truncating a file bigger than it was then
 296          * trying to write into the hole.
 297          */
 298         if (MSDOS_I(inode)->mmu_private > offset)
 299                 MSDOS_I(inode)->mmu_private = offset;
 300
 301         nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
 302
 303         fat_free(inode, nr_clusters);
 304         fat_flush_inodes(inode->i_sb, inode, NULL);
 305 }
 306
 307 int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 308 {
 309         struct inode *inode = d_inode(dentry);
 310         generic_fillattr(inode, stat);
 311         stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
 312
 313         if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
 314                 /* Use i_pos for ino. This is used as fileid of nfs. */
 315                 stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
 316         }
 317         return 0;
 318 }
 319 EXPORT_SYMBOL_GPL(fat_getattr);
 320
 321 static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
 322                              struct inode *inode, umode_t *mode_ptr)
 323 {
 324         umode_t mask, perm;
 325
 326         /*
 327          * Note, the basic check is already done by a caller of
 328          * (attr->ia_mode & ~FAT_VALID_MODE)
 329          */
 330
 331         if (S_ISREG(inode->i_mode))
 332                 mask = sbi->options.fs_fmask;
 333         else
 334                 mask = sbi->options.fs_dmask;
 335
 336         perm = *mode_ptr & ~(S_IFMT | mask);
 337
 338         /*
 339          * Of the r and x bits, all (subject to umask) must be present. Of the
 340          * w bits, either all (subject to umask) or none must be present.
 341          *
 342          * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
 343          */
 344         if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
 345                 return -EPERM;
 346         if (fat_mode_can_hold_ro(inode)) {
 347                 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
 348                         return -EPERM;
 349         } else {
 350                 if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
 351                         return -EPERM;
 352         }
 353
 354         *mode_ptr &= S_IFMT | perm;
 355
 356         return 0;
 357 }
 358
 359 static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
 360 {
 361         umode_t allow_utime = sbi->options.allow_utime;
 362
 363         if (!uid_eq(current_fsuid(), inode->i_uid)) {
 364                 if (in_group_p(inode->i_gid))
 365                         allow_utime >>= 3;
 366                 if (allow_utime & MAY_WRITE)
 367                         return 1;
 368         }
 369
 370         /* use a default check */
 371         return 0;
 372 }
 373
 374 #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
 375 /* valid file mode bits */
 376 #define FAT_VALID_MODE  (S_IFREG | S_IFDIR | S_IRWXUGO)
 377
 378 int fat_setattr(struct dentry *dentry, struct iattr *attr)
 379 {
 380         struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 381         struct inode *inode = d_inode(dentry);
 382         unsigned int ia_valid;
 383         int error;
 384
 385         /* Check for setting the inode time. */
 386         ia_valid = attr->ia_valid;
 387         if (ia_valid & TIMES_SET_FLAGS) {
 388                 if (fat_allow_set_time(sbi, inode))
 389                         attr->ia_valid &= ~TIMES_SET_FLAGS;
 390         }
 391
 392         error = inode_change_ok(inode, attr);
 393         attr->ia_valid = ia_valid;
 394         if (error) {
 395                 if (sbi->options.quiet)
 396                         error = 0;
 397                 goto out;
 398         }
 399
 400         /*
 401          * Expand the file. Since inode_setattr() updates ->i_size
 402          * before calling the ->truncate(), but FAT needs to fill the
 403          * hole before it. XXX: this is no longer true with new truncate
 404          * sequence.
 405          */
 406         if (attr->ia_valid & ATTR_SIZE) {
 407                 inode_dio_wait(inode);
 408
 409                 if (attr->ia_size > inode->i_size) {
 410                         error = fat_cont_expand(inode, attr->ia_size);
 411                         if (error || attr->ia_valid == ATTR_SIZE)
 412                                 goto out;
 413                         attr->ia_valid &= ~ATTR_SIZE;
 414                 }
 415         }
 416
 417         if (((attr->ia_valid & ATTR_UID) &&
 418              (!uid_eq(attr->ia_uid, sbi->options.fs_uid))) ||
 419             ((attr->ia_valid & ATTR_GID) &&
 420              (!gid_eq(attr->ia_gid, sbi->options.fs_gid))) ||
 421             ((attr->ia_valid & ATTR_MODE) &&
 422              (attr->ia_mode & ~FAT_VALID_MODE)))
 423                 error = -EPERM;
 424
 425         if (error) {
 426                 if (sbi->options.quiet)
 427                         error = 0;
 428                 goto out;
 429         }
 430
 431         /*
 432          * We don't return -EPERM here. Yes, strange, but this is too
 433          * old behavior.
 434          */
 435         if (attr->ia_valid & ATTR_MODE) {
 436                 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
 437                         attr->ia_valid &= ~ATTR_MODE;
 438         }
 439
 440         if (attr->ia_valid & ATTR_SIZE) {
 441                 error = fat_block_truncate_page(inode, attr->ia_size);
 442                 if (error)
 443                         goto out;
 444                 down_write(&MSDOS_I(inode)->truncate_lock);
 445                 truncate_setsize(inode, attr->ia_size);
 446                 fat_truncate_blocks(inode, attr->ia_size);
 447                 up_write(&MSDOS_I(inode)->truncate_lock);
 448         }
 449
 450         setattr_copy(inode, attr);
 451         mark_inode_dirty(inode);
 452 out:
 453         return error;
 454 }
 455 EXPORT_SYMBOL_GPL(fat_setattr);
 456
 457 const struct inode_operations fat_file_inode_operations = {
 458         .setattr        = fat_setattr,
 459         .getattr        = fat_getattr,
 460 };