fs/ntfs3: Do not update primary boot in ntfs_init_from_boot()

'cause it may be faked boot.
Let ntfs to be mounted and update boot later.

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>

diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
index ecf899d..2b48b45 100644 (file)
--- a/fs/ntfs3/super.c
+++ b/fs/ntfs3/super.c
@@ -711,9 +711,16 @@ static u32 true_sectors_per_clst(const struct NTFS_BOOT *boot)
 
 /*
  * ntfs_init_from_boot - Init internal info from on-disk boot sector.
+ *
+ * NTFS mount begins from boot - special formatted 512 bytes.
+ * There are two boots: the first and the last 512 bytes of volume.
+ * The content of boot is not changed during ntfs life.
+ *
+ * NOTE: ntfs.sys checks only first (primary) boot.
+ * chkdsk checks both boots.
  */
 static int ntfs_init_from_boot(struct super_block *sb, u32 sector_size,
-                              u64 dev_size)
+                              u64 dev_size, struct NTFS_BOOT **boot2)
 {
        struct ntfs_sb_info *sbi = sb->s_fs_info;
        int err;
@@ -937,23 +944,11 @@ check_boot:
 
        if (bh->b_blocknr && !sb_rdonly(sb)) {
                /*
-                * Alternative boot is ok but primary is not ok.
-                * Update primary boot.
-                */
-               struct buffer_head *bh0 = sb_getblk(sb, 0);
-               if (bh0) {
-                       if (buffer_locked(bh0))
-                               __wait_on_buffer(bh0);
-
-                       lock_buffer(bh0);
-                       memcpy(bh0->b_data, boot, sizeof(*boot));
-                       set_buffer_uptodate(bh0);
-                       mark_buffer_dirty(bh0);
-                       unlock_buffer(bh0);
-                       if (!sync_dirty_buffer(bh0))
-                               ntfs_warn(sb, "primary boot is updated");
-                       put_bh(bh0);
-               }
+            * Alternative boot is ok but primary is not ok.
+            * Do not update primary boot here 'cause it may be faked boot.
+            * Let ntfs to be mounted and update boot later.
+            */
+               *boot2 = kmemdup(boot, sizeof(*boot), GFP_NOFS | __GFP_NOWARN);
        }
 
 out:
@@ -1000,6 +995,7 @@ static int ntfs_fill_super(struct super_block *sb, struct fs_context *fc)
        u16 *shared;
        struct MFT_REF ref;
        bool ro = sb_rdonly(sb);
+       struct NTFS_BOOT *boot2 = NULL;
 
        ref.high = 0;
 
@@ -1030,7 +1026,7 @@ static int ntfs_fill_super(struct super_block *sb, struct fs_context *fc)
 
        /* Parse boot. */
        err = ntfs_init_from_boot(sb, bdev_logical_block_size(bdev),
-                                 bdev_nr_bytes(bdev));
+                                 bdev_nr_bytes(bdev), &boot2);
        if (err)
                goto out;
 
@@ -1412,6 +1408,29 @@ load_root:
                goto put_inode_out;
        }
 
+       if (boot2) {
+               /*
+            * Alternative boot is ok but primary is not ok.
+            * Volume is recognized as NTFS. Update primary boot.
+            */
+               struct buffer_head *bh0 = sb_getblk(sb, 0);
+               if (bh0) {
+                       if (buffer_locked(bh0))
+                               __wait_on_buffer(bh0);
+
+                       lock_buffer(bh0);
+                       memcpy(bh0->b_data, boot2, sizeof(*boot2));
+                       set_buffer_uptodate(bh0);
+                       mark_buffer_dirty(bh0);
+                       unlock_buffer(bh0);
+                       if (!sync_dirty_buffer(bh0))
+                               ntfs_warn(sb, "primary boot is updated");
+                       put_bh(bh0);
+               }
+
+               kfree(boot2);
+       }
+
        return 0;
 
 put_inode_out:
@@ -1424,6 +1443,7 @@ out:
        put_mount_options(sbi->options);
        put_ntfs(sbi);
        sb->s_fs_info = NULL;
+       kfree(boot2);
 
        return err;
 }