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 static int fat_ioctl_get_volume_id(struct inode *inode, u32 __user *user_attr)
 118 {
 119         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 120         return put_user(sbi->vol_id, user_attr);
 121 }
 122
 123 long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 124 {
 125         struct inode *inode = file_inode(filp);
 126         u32 __user *user_attr = (u32 __user *)arg;
 127
 128         switch (cmd) {
 129         case FAT_IOCTL_GET_ATTRIBUTES:
 130                 return fat_ioctl_get_attributes(inode, user_attr);
 131         case FAT_IOCTL_SET_ATTRIBUTES:
 132                 return fat_ioctl_set_attributes(filp, user_attr);
 133         case FAT_IOCTL_GET_VOLUME_ID:
 134                 return fat_ioctl_get_volume_id(inode, user_attr);
 135         default:
 136                 return -ENOTTY; /* Inappropriate ioctl for device */
 137         }
 138 }
 139
 140 #ifdef CONFIG_COMPAT
 141 static long fat_generic_compat_ioctl(struct file *filp, unsigned int cmd,
 142                                       unsigned long arg)
 143
 144 {
 145         return fat_generic_ioctl(filp, cmd, (unsigned long)compat_ptr(arg));
 146 }
 147 #endif
 148
 149 static int fat_file_release(struct inode *inode, struct file *filp)
 150 {
 151         if ((filp->f_mode & FMODE_WRITE) &&
 152              MSDOS_SB(inode->i_sb)->options.flush) {
 153                 fat_flush_inodes(inode->i_sb, inode, NULL);
 154                 congestion_wait(BLK_RW_ASYNC, HZ/10);
 155         }
 156         return 0;
 157 }
 158
 159 int fat_file_fsync(struct file *filp, loff_t start, loff_t end, int datasync)
 160 {
 161         struct inode *inode = filp->f_mapping->host;
 162         int res, err;
 163
 164         res = generic_file_fsync(filp, start, end, datasync);
 165         err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
 166
 167         return res ? res : err;
 168 }
 169
 170
 171 const struct file_operations fat_file_operations = {
 172         .llseek         = generic_file_llseek,
 173         .read           = new_sync_read,
 174         .write          = new_sync_write,
 175         .read_iter      = generic_file_read_iter,
 176         .write_iter     = generic_file_write_iter,
 177         .mmap           = generic_file_mmap,
 178         .release        = fat_file_release,
 179         .unlocked_ioctl = fat_generic_ioctl,
 180 #ifdef CONFIG_COMPAT
 181         .compat_ioctl   = fat_generic_compat_ioctl,
 182 #endif
 183         .fsync          = fat_file_fsync,
 184         .splice_read    = generic_file_splice_read,
 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_SEC;
 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 /* Free all clusters after the skip'th cluster. */
 224 static int fat_free(struct inode *inode, int skip)
 225 {
 226         struct super_block *sb = inode->i_sb;
 227         int err, wait, free_start, i_start, i_logstart;
 228
 229         if (MSDOS_I(inode)->i_start == 0)
 230                 return 0;
 231
 232         fat_cache_inval_inode(inode);
 233
 234         wait = IS_DIRSYNC(inode);
 235         i_start = free_start = MSDOS_I(inode)->i_start;
 236         i_logstart = MSDOS_I(inode)->i_logstart;
 237
 238         /* First, we write the new file size. */
 239         if (!skip) {
 240                 MSDOS_I(inode)->i_start = 0;
 241                 MSDOS_I(inode)->i_logstart = 0;
 242         }
 243         MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
 244         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 245         if (wait) {
 246                 err = fat_sync_inode(inode);
 247                 if (err) {
 248                         MSDOS_I(inode)->i_start = i_start;
 249                         MSDOS_I(inode)->i_logstart = i_logstart;
 250                         return err;
 251                 }
 252         } else
 253                 mark_inode_dirty(inode);
 254
 255         /* Write a new EOF, and get the remaining cluster chain for freeing. */
 256         if (skip) {
 257                 struct fat_entry fatent;
 258                 int ret, fclus, dclus;
 259
 260                 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
 261                 if (ret < 0)
 262                         return ret;
 263                 else if (ret == FAT_ENT_EOF)
 264                         return 0;
 265
 266                 fatent_init(&fatent);
 267                 ret = fat_ent_read(inode, &fatent, dclus);
 268                 if (ret == FAT_ENT_EOF) {
 269                         fatent_brelse(&fatent);
 270                         return 0;
 271                 } else if (ret == FAT_ENT_FREE) {
 272                         fat_fs_error(sb,
 273                                      "%s: invalid cluster chain (i_pos %lld)",
 274                                      __func__, MSDOS_I(inode)->i_pos);
 275                         ret = -EIO;
 276                 } else if (ret > 0) {
 277                         err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
 278                         if (err)
 279                                 ret = err;
 280                 }
 281                 fatent_brelse(&fatent);
 282                 if (ret < 0)
 283                         return ret;
 284
 285                 free_start = ret;
 286         }
 287         inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
 288
 289         /* Freeing the remained cluster chain */
 290         return fat_free_clusters(inode, free_start);
 291 }
 292
 293 void fat_truncate_blocks(struct inode *inode, loff_t offset)
 294 {
 295         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
 296         const unsigned int cluster_size = sbi->cluster_size;
 297         int nr_clusters;
 298
 299         /*
 300          * This protects against truncating a file bigger than it was then
 301          * trying to write into the hole.
 302          */
 303         if (MSDOS_I(inode)->mmu_private > offset)
 304                 MSDOS_I(inode)->mmu_private = offset;
 305
 306         nr_clusters = (offset + (cluster_size - 1)) >> sbi->cluster_bits;
 307
 308         fat_free(inode, nr_clusters);
 309         fat_flush_inodes(inode->i_sb, inode, NULL);
 310 }
 311
 312 int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
 313 {
 314         struct inode *inode = dentry->d_inode;
 315         generic_fillattr(inode, stat);
 316         stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
 317
 318         if (MSDOS_SB(inode->i_sb)->options.nfs == FAT_NFS_NOSTALE_RO) {
 319                 /* Use i_pos for ino. This is used as fileid of nfs. */
 320                 stat->ino = fat_i_pos_read(MSDOS_SB(inode->i_sb), inode);
 321         }
 322         return 0;
 323 }
 324 EXPORT_SYMBOL_GPL(fat_getattr);
 325
 326 static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
 327                              struct inode *inode, umode_t *mode_ptr)
 328 {
 329         umode_t mask, perm;
 330
 331         /*
 332          * Note, the basic check is already done by a caller of
 333          * (attr->ia_mode & ~FAT_VALID_MODE)
 334          */
 335
 336         if (S_ISREG(inode->i_mode))
 337                 mask = sbi->options.fs_fmask;
 338         else
 339                 mask = sbi->options.fs_dmask;
 340
 341         perm = *mode_ptr & ~(S_IFMT | mask);
 342
 343         /*
 344          * Of the r and x bits, all (subject to umask) must be present. Of the
 345          * w bits, either all (subject to umask) or none must be present.
 346          *
 347          * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
 348          */
 349         if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
 350                 return -EPERM;
 351         if (fat_mode_can_hold_ro(inode)) {
 352                 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
 353                         return -EPERM;
 354         } else {
 355                 if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
 356                         return -EPERM;
 357         }
 358
 359         *mode_ptr &= S_IFMT | perm;
 360
 361         return 0;
 362 }
 363
 364 static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
 365 {
 366         umode_t allow_utime = sbi->options.allow_utime;
 367
 368         if (!uid_eq(current_fsuid(), inode->i_uid)) {
 369                 if (in_group_p(inode->i_gid))
 370                         allow_utime >>= 3;
 371                 if (allow_utime & MAY_WRITE)
 372                         return 1;
 373         }
 374
 375         /* use a default check */
 376         return 0;
 377 }
 378
 379 #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
 380 /* valid file mode bits */
 381 #define FAT_VALID_MODE  (S_IFREG | S_IFDIR | S_IRWXUGO)
 382
 383 int fat_setattr(struct dentry *dentry, struct iattr *attr)
 384 {
 385         struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
 386         struct inode *inode = dentry->d_inode;
 387         unsigned int ia_valid;
 388         int error;
 389
 390         /* Check for setting the inode time. */
 391         ia_valid = attr->ia_valid;
 392         if (ia_valid & TIMES_SET_FLAGS) {
 393                 if (fat_allow_set_time(sbi, inode))
 394                         attr->ia_valid &= ~TIMES_SET_FLAGS;
 395         }
 396
 397         error = inode_change_ok(inode, attr);
 398         attr->ia_valid = ia_valid;
 399         if (error) {
 400                 if (sbi->options.quiet)
 401                         error = 0;
 402                 goto out;
 403         }
 404
 405         /*
 406          * Expand the file. Since inode_setattr() updates ->i_size
 407          * before calling the ->truncate(), but FAT needs to fill the
 408          * hole before it. XXX: this is no longer true with new truncate
 409          * sequence.
 410          */
 411         if (attr->ia_valid & ATTR_SIZE) {
 412                 inode_dio_wait(inode);
 413
 414                 if (attr->ia_size > inode->i_size) {
 415                         error = fat_cont_expand(inode, attr->ia_size);
 416                         if (error || attr->ia_valid == ATTR_SIZE)
 417                                 goto out;
 418                         attr->ia_valid &= ~ATTR_SIZE;
 419                 }
 420         }
 421
 422         if (((attr->ia_valid & ATTR_UID) &&
 423              (!uid_eq(attr->ia_uid, sbi->options.fs_uid))) ||
 424             ((attr->ia_valid & ATTR_GID) &&
 425              (!gid_eq(attr->ia_gid, sbi->options.fs_gid))) ||
 426             ((attr->ia_valid & ATTR_MODE) &&
 427              (attr->ia_mode & ~FAT_VALID_MODE)))
 428                 error = -EPERM;
 429
 430         if (error) {
 431                 if (sbi->options.quiet)
 432                         error = 0;
 433                 goto out;
 434         }
 435
 436         /*
 437          * We don't return -EPERM here. Yes, strange, but this is too
 438          * old behavior.
 439          */
 440         if (attr->ia_valid & ATTR_MODE) {
 441                 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
 442                         attr->ia_valid &= ~ATTR_MODE;
 443         }
 444
 445         if (attr->ia_valid & ATTR_SIZE) {
 446                 down_write(&MSDOS_I(inode)->truncate_lock);
 447                 truncate_setsize(inode, attr->ia_size);
 448                 fat_truncate_blocks(inode, attr->ia_size);
 449                 up_write(&MSDOS_I(inode)->truncate_lock);
 450         }
 451
 452         setattr_copy(inode, attr);
 453         mark_inode_dirty(inode);
 454 out:
 455         return error;
 456 }
 457 EXPORT_SYMBOL_GPL(fat_setattr);
 458
 459 const struct inode_operations fat_file_inode_operations = {
 460         .setattr        = fat_setattr,
 461         .getattr        = fat_getattr,
 462 };