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