LCOV - code coverage report
Current view: top level - lkbce/fs/fat - file.c (source / functions) Hit Total Coverage
Test: coverage.info Lines: 221 221 100.0 %
Date: 2017-01-25 Functions: 12 12 100.0 %

          Line data    Source code
       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/mount.h>
      12             : #include <linux/time.h>
      13             : #include <linux/buffer_head.h>
      14             : #include <linux/writeback.h>
      15             : #include <linux/backing-dev.h>
      16             : #include <linux/blkdev.h>
      17             : #include <linux/fsnotify.h>
      18             : #include <linux/security.h>
      19             : #include "fat.h"
      20             : 
      21             : static int fat_ioctl_get_attributes(struct inode *inode, u32 __user *user_attr)
      22             : {
      23           2 :         u32 attr;
      24           2 : 
      25           4 :         mutex_lock(&inode->i_mutex);
      26           8 :         attr = fat_make_attrs(inode);
      27           2 :         mutex_unlock(&inode->i_mutex);
      28             : 
      29          20 :         return put_user(attr, user_attr);
      30           2 : }
      31             : 
      32             : static int fat_ioctl_set_attributes(struct file *file, u32 __user *user_attr)
      33             : {
      34           4 :         struct inode *inode = file->f_path.dentry->d_inode;
      35           8 :         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
      36           6 :         int is_dir = S_ISDIR(inode->i_mode);
      37           2 :         u32 attr, oldattr;
      38           2 :         struct iattr ia;
      39           2 :         int err;
      40           2 : 
      41          22 :         err = get_user(attr, user_attr);
      42           8 :         if (err)
      43           4 :                 goto out;
      44           2 : 
      45           4 :         mutex_lock(&inode->i_mutex);
      46           4 :         err = mnt_want_write(file->f_path.mnt);
      47           6 :         if (err)
      48           4 :                 goto out_unlock_inode;
      49             : 
      50             :         /*
      51             :          * ATTR_VOLUME and ATTR_DIR cannot be changed; this also
      52             :          * prevents the user from turning us into a VFAT
      53             :          * longname entry.  Also, we obviously can't set
      54             :          * any of the NTFS attributes in the high 24 bits.
      55             :          */
      56           2 :         attr &= 0xff & ~(ATTR_VOLUME | ATTR_DIR);
      57             :         /* Merge in ATTR_VOLUME and ATTR_DIR */
      58          16 :         attr |= (MSDOS_I(inode)->i_attrs & ATTR_VOLUME) |
      59             :                 (is_dir ? ATTR_DIR : 0);
      60           6 :         oldattr = fat_make_attrs(inode);
      61             : 
      62             :         /* Equivalent to a chmod() */
      63           2 :         ia.ia_valid = ATTR_MODE | ATTR_CTIME;
      64           2 :         ia.ia_ctime = current_fs_time(inode->i_sb);
      65           4 :         if (is_dir)
      66           6 :                 ia.ia_mode = fat_make_mode(sbi, attr, S_IRWXUGO);
      67             :         else {
      68           8 :                 ia.ia_mode = fat_make_mode(sbi, attr,
      69             :                         S_IRUGO | S_IWUGO | (inode->i_mode & S_IXUGO));
      70             :         }
      71             : 
      72             :         /* The root directory has no attributes */
      73          16 :         if (inode->i_ino == MSDOS_ROOT_INO && attr != ATTR_DIR) {
      74           4 :                 err = -EINVAL;
      75           4 :                 goto out_drop_write;
      76             :         }
      77             : 
      78          28 :         if (sbi->options.sys_immutable &&
      79             :             ((attr | oldattr) & ATTR_SYS) &&
      80             :             !capable(CAP_LINUX_IMMUTABLE)) {
      81           4 :                 err = -EPERM;
      82           4 :                 goto out_drop_write;
      83             :         }
      84             : 
      85             :         /*
      86             :          * The security check is questionable...  We single
      87             :          * out the RO attribute for checking by the security
      88             :          * module, just because it maps to a file mode.
      89             :          */
      90           8 :         err = security_inode_setattr(file->f_path.dentry, &ia);
      91           4 :         if (err)
      92           2 :                 goto out_drop_write;
      93             : 
      94             :         /* This MUST be done before doing anything irreversible... */
      95          10 :         err = fat_setattr(file->f_path.dentry, &ia);
      96           4 :         if (err)
      97           2 :                 goto out_drop_write;
      98             : 
      99           6 :         fsnotify_change(file->f_path.dentry, ia.ia_valid);
     100           4 :         if (sbi->options.sys_immutable) {
     101           4 :                 if (attr & ATTR_SYS)
     102           2 :                         inode->i_flags |= S_IMMUTABLE;
     103             :                 else
     104           2 :                         inode->i_flags &= ~S_IMMUTABLE;
     105             :         }
     106             : 
     107           6 :         fat_save_attrs(inode, attr);
     108           4 :         mark_inode_dirty(inode);
     109             : out_drop_write:
     110          12 :         mnt_drop_write(file->f_path.mnt);
     111             : out_unlock_inode:
     112          22 :         mutex_unlock(&inode->i_mutex);
     113             : out:
     114          24 :         return err;
     115             : }
     116             : 
     117             : int fat_generic_ioctl(struct inode *inode, struct file *filp,
     118             :                       unsigned int cmd, unsigned long arg)
     119             : {
     120           4 :         u32 __user *user_attr = (u32 __user *)arg;
     121           2 : 
     122           2 :         switch (cmd) {
     123           6 :         case FAT_IOCTL_GET_ATTRIBUTES:
     124           6 :                 return fat_ioctl_get_attributes(inode, user_attr);
     125           8 :         case FAT_IOCTL_SET_ATTRIBUTES:
     126          16 :                 return fat_ioctl_set_attributes(filp, user_attr);
     127           4 :         default:
     128           4 :                 return -ENOTTY; /* Inappropriate ioctl for device */
     129             :         }
     130             : }
     131             : 
     132             : static int fat_file_release(struct inode *inode, struct file *filp)
     133             : {
     134           7 :         if ((filp->f_mode & FMODE_WRITE) &&
     135             :              MSDOS_SB(inode->i_sb)->options.flush) {
     136           4 :                 fat_flush_inodes(inode->i_sb, inode, NULL);
     137           1 :                 congestion_wait(BLK_RW_ASYNC, HZ/10);
     138             :         }
     139           3 :         return 0;
     140             : }
     141             : 
     142             : int fat_file_fsync(struct file *filp, struct dentry *dentry, int datasync)
     143             : {
     144           4 :         struct inode *inode = dentry->d_inode;
     145           2 :         int res, err;
     146           2 : 
     147           4 :         res = simple_fsync(filp, dentry, datasync);
     148           6 :         err = sync_mapping_buffers(MSDOS_SB(inode->i_sb)->fat_inode->i_mapping);
     149             : 
     150          12 :         return res ? res : err;
     151             : }
     152             : 
     153             : 
     154           1 : const struct file_operations fat_file_operations = {
     155             :         .llseek         = generic_file_llseek,
     156             :         .read           = do_sync_read,
     157             :         .write          = do_sync_write,
     158             :         .aio_read       = generic_file_aio_read,
     159             :         .aio_write      = generic_file_aio_write,
     160             :         .mmap           = generic_file_mmap,
     161             :         .release        = fat_file_release,
     162             :         .ioctl          = fat_generic_ioctl,
     163             :         .fsync          = fat_file_fsync,
     164             :         .splice_read    = generic_file_splice_read,
     165             : };
     166             : 
     167             : static int fat_cont_expand(struct inode *inode, loff_t size)
     168             : {
     169           6 :         struct address_space *mapping = inode->i_mapping;
     170           9 :         loff_t start = inode->i_size, count = size - inode->i_size;
     171           3 :         int err;
     172           3 : 
     173           6 :         err = generic_cont_expand_simple(inode, size);
     174           9 :         if (err)
     175           6 :                 goto out;
     176           3 : 
     177          18 :         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
     178           6 :         mark_inode_dirty(inode);
     179          15 :         if (IS_SYNC(inode)) {
     180             :                 int err2;
     181             : 
     182             :                 /*
     183             :                  * Opencode syncing since we don't have a file open to use
     184             :                  * standard fsync path.
     185             :                  */
     186           3 :                 err = filemap_fdatawrite_range(mapping, start,
     187             :                                                start + count - 1);
     188           3 :                 err2 = sync_mapping_buffers(mapping);
     189           6 :                 if (!err)
     190           3 :                         err = err2;
     191           3 :                 err2 = write_inode_now(inode, 1);
     192           6 :                 if (!err)
     193           3 :                         err = err2;
     194           6 :                 if (!err) {
     195           3 :                         err =  filemap_fdatawait_range(mapping, start,
     196             :                                                        start + count - 1);
     197             :                 }
     198             :         }
     199             : out:
     200           6 :         return err;
     201             : }
     202             : 
     203           3 : /* Free all clusters after the skip'th cluster. */
     204             : static int fat_free(struct inode *inode, int skip)
     205             : {
     206           8 :         struct super_block *sb = inode->i_sb;
     207           4 :         int err, wait, free_start, i_start, i_logstart;
     208           4 : 
     209          20 :         if (MSDOS_I(inode)->i_start == 0)
     210           8 :                 return 0;
     211           4 : 
     212          12 :         fat_cache_inval_inode(inode);
     213           4 : 
     214          28 :         wait = IS_DIRSYNC(inode);
     215          20 :         i_start = free_start = MSDOS_I(inode)->i_start;
     216          16 :         i_logstart = MSDOS_I(inode)->i_logstart;
     217           4 : 
     218           4 :         /* First, we write the new file size. */
     219          12 :         if (!skip) {
     220          16 :                 MSDOS_I(inode)->i_start = 0;
     221          16 :                 MSDOS_I(inode)->i_logstart = 0;
     222           4 :         }
     223          24 :         MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
     224          28 :         inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
     225          12 :         if (wait) {
     226          12 :                 err = fat_sync_inode(inode);
     227          12 :                 if (err) {
     228          16 :                         MSDOS_I(inode)->i_start = i_start;
     229          16 :                         MSDOS_I(inode)->i_logstart = i_logstart;
     230           4 :                         return err;
     231             :                 }
     232             :         } else
     233           8 :                 mark_inode_dirty(inode);
     234             : 
     235             :         /* Write a new EOF, and get the remaining cluster chain for freeing. */
     236          16 :         if (skip) {
     237             :                 struct fat_entry fatent;
     238             :                 int ret, fclus, dclus;
     239             : 
     240          24 :                 ret = fat_get_cluster(inode, skip - 1, &fclus, &dclus);
     241           8 :                 if (ret < 0)
     242           4 :                         return ret;
     243           8 :                 else if (ret == FAT_ENT_EOF)
     244           4 :                         return 0;
     245             : 
     246           8 :                 fatent_init(&fatent);
     247          16 :                 ret = fat_ent_read(inode, &fatent, dclus);
     248           8 :                 if (ret == FAT_ENT_EOF) {
     249           8 :                         fatent_brelse(&fatent);
     250           4 :                         return 0;
     251           8 :                 } else if (ret == FAT_ENT_FREE) {
     252          16 :                         fat_fs_error(sb,
     253             :                                      "%s: invalid cluster chain (i_pos %lld)",
     254             :                                      __func__, MSDOS_I(inode)->i_pos);
     255           4 :                         ret = -EIO;
     256           8 :                 } else if (ret > 0) {
     257          12 :                         err = fat_ent_write(inode, &fatent, FAT_ENT_EOF, wait);
     258           8 :                         if (err)
     259           4 :                                 ret = err;
     260             :                 }
     261          24 :                 fatent_brelse(&fatent);
     262           8 :                 if (ret < 0)
     263           4 :                         return ret;
     264             : 
     265           4 :                 free_start = ret;
     266             :         }
     267          32 :         inode->i_blocks = skip << (MSDOS_SB(sb)->cluster_bits - 9);
     268             : 
     269             :         /* Freeing the remained cluster chain */
     270          12 :         return fat_free_clusters(inode, free_start);
     271             : }
     272             : 
     273             : void fat_truncate(struct inode *inode)
     274             : {
     275           8 :         struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
     276           4 :         const unsigned int cluster_size = sbi->cluster_size;
     277           2 :         int nr_clusters;
     278           2 : 
     279           2 :         /*
     280           2 :          * This protects against truncating a file bigger than it was then
     281             :          * trying to write into the hole.
     282             :          */
     283           8 :         if (MSDOS_I(inode)->mmu_private > inode->i_size)
     284           6 :                 MSDOS_I(inode)->mmu_private = inode->i_size;
     285             : 
     286           8 :         nr_clusters = (inode->i_size + (cluster_size - 1)) >> sbi->cluster_bits;
     287             : 
     288          28 :         fat_free(inode, nr_clusters);
     289           8 :         fat_flush_inodes(inode->i_sb, inode, NULL);
     290           2 : }
     291             : 
     292             : int fat_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
     293             : {
     294           2 :         struct inode *inode = dentry->d_inode;
     295           2 :         generic_fillattr(inode, stat);
     296           4 :         stat->blksize = MSDOS_SB(inode->i_sb)->cluster_size;
     297           1 :         return 0;
     298             : }
     299             : EXPORT_SYMBOL_GPL(fat_getattr);
     300             : 
     301             : static int fat_sanitize_mode(const struct msdos_sb_info *sbi,
     302             :                              struct inode *inode, umode_t *mode_ptr)
     303             : {
     304           9 :         mode_t mask, perm;
     305           9 : 
     306           9 :         /*
     307             :          * Note, the basic check is already done by a caller of
     308             :          * (attr->ia_mode & ~FAT_VALID_MODE)
     309             :          */
     310             : 
     311          27 :         if (S_ISREG(inode->i_mode))
     312           9 :                 mask = sbi->options.fs_fmask;
     313             :         else
     314           9 :                 mask = sbi->options.fs_dmask;
     315             : 
     316           9 :         perm = *mode_ptr & ~(S_IFMT | mask);
     317             : 
     318             :         /*
     319             :          * Of the r and x bits, all (subject to umask) must be present. Of the
     320             :          * w bits, either all (subject to umask) or none must be present.
     321             :          *
     322             :          * If fat_mode_can_hold_ro(inode) is false, can't change w bits.
     323             :          */
     324          27 :         if ((perm & (S_IRUGO | S_IXUGO)) != (inode->i_mode & (S_IRUGO|S_IXUGO)))
     325           9 :                 return -EPERM;
     326          36 :         if (fat_mode_can_hold_ro(inode)) {
     327          36 :                 if ((perm & S_IWUGO) && ((perm & S_IWUGO) != (S_IWUGO & ~mask)))
     328           9 :                         return -EPERM;
     329             :         } else {
     330          18 :                 if ((perm & S_IWUGO) != (S_IWUGO & ~mask))
     331           9 :                         return -EPERM;
     332             :         }
     333             : 
     334           9 :         *mode_ptr &= S_IFMT | perm;
     335             : 
     336           9 :         return 0;
     337             : }
     338             : 
     339             : static int fat_allow_set_time(struct msdos_sb_info *sbi, struct inode *inode)
     340             : {
     341          12 :         mode_t allow_utime = sbi->options.allow_utime;
     342           6 : 
     343          36 :         if (current_fsuid() != inode->i_uid) {
     344          18 :                 if (in_group_p(inode->i_gid))
     345           6 :                         allow_utime >>= 3;
     346          12 :                 if (allow_utime & MAY_WRITE)
     347           6 :                         return 1;
     348             :         }
     349             : 
     350             :         /* use a default check */
     351           6 :         return 0;
     352             : }
     353             : 
     354             : #define TIMES_SET_FLAGS (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)
     355             : /* valid file mode bits */
     356             : #define FAT_VALID_MODE  (S_IFREG | S_IFDIR | S_IRWXUGO)
     357             : 
     358             : int fat_setattr(struct dentry *dentry, struct iattr *attr)
     359             : {
     360          12 :         struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb);
     361           6 :         struct inode *inode = dentry->d_inode;
     362           3 :         unsigned int ia_valid;
     363           3 :         int error;
     364           3 : 
     365           3 :         /*
     366           3 :          * Expand the file. Since inode_setattr() updates ->i_size
     367             :          * before calling the ->truncate(), but FAT needs to fill the
     368             :          * hole before it.
     369             :          */
     370           6 :         if (attr->ia_valid & ATTR_SIZE) {
     371           6 :                 if (attr->ia_size > inode->i_size) {
     372           9 :                         error = fat_cont_expand(inode, attr->ia_size);
     373          12 :                         if (error || attr->ia_valid == ATTR_SIZE)
     374           3 :                                 goto out;
     375           3 :                         attr->ia_valid &= ~ATTR_SIZE;
     376             :                 }
     377             :         }
     378             : 
     379             :         /* Check for setting the inode time. */
     380           6 :         ia_valid = attr->ia_valid;
     381          12 :         if (ia_valid & TIMES_SET_FLAGS) {
     382          18 :                 if (fat_allow_set_time(sbi, inode))
     383           3 :                         attr->ia_valid &= ~TIMES_SET_FLAGS;
     384             :         }
     385             : 
     386           9 :         error = inode_change_ok(inode, attr);
     387           9 :         attr->ia_valid = ia_valid;
     388          18 :         if (error) {
     389          18 :                 if (sbi->options.quiet)
     390           9 :                         error = 0;
     391           9 :                 goto out;
     392             :         }
     393             : 
     394         126 :         if (((attr->ia_valid & ATTR_UID) &&
     395             :              (attr->ia_uid != sbi->options.fs_uid)) ||
     396             :             ((attr->ia_valid & ATTR_GID) &&
     397             :              (attr->ia_gid != sbi->options.fs_gid)) ||
     398             :             ((attr->ia_valid & ATTR_MODE) &&
     399             :              (attr->ia_mode & ~FAT_VALID_MODE)))
     400           9 :                 error = -EPERM;
     401             : 
     402          18 :         if (error) {
     403          18 :                 if (sbi->options.quiet)
     404           9 :                         error = 0;
     405           9 :                 goto out;
     406             :         }
     407             : 
     408             :         /*
     409             :          * We don't return -EPERM here. Yes, strange, but this is too
     410             :          * old behavior.
     411             :          */
     412          27 :         if (attr->ia_valid & ATTR_MODE) {
     413          33 :                 if (fat_sanitize_mode(sbi, inode, &attr->ia_mode) < 0)
     414           3 :                         attr->ia_valid &= ~ATTR_MODE;
     415             :         }
     416             : 
     417          24 :         if (attr->ia_valid)
     418          12 :                 error = inode_setattr(inode, attr);
     419             : out:
     420          12 :         return error;
     421             : }
     422             : EXPORT_SYMBOL_GPL(fat_setattr);
     423          12 : 
     424           1 : const struct inode_operations fat_file_inode_operations = {
     425             :         .truncate       = fat_truncate,
     426             :         .setattr        = fat_setattr,
     427             :         .getattr        = fat_getattr,
     428             : };

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