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