ext3: add block bitmap validation
When a new block bitmap is read from disk in read_block_bitmap() there are a few bits that should ALWAYS be set. In particular, the blocks given corresponding to block bitmap, inode bitmap and inode tables. Validate the block bitmap against these blocks. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -80,13 +80,57 @@ struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
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return desc + offset;
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}
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static int ext3_valid_block_bitmap(struct super_block *sb,
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struct ext3_group_desc *desc,
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unsigned int block_group,
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struct buffer_head *bh)
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{
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ext3_grpblk_t offset;
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ext3_grpblk_t next_zero_bit;
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ext3_fsblk_t bitmap_blk;
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ext3_fsblk_t group_first_block;
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group_first_block = ext3_group_first_block_no(sb, block_group);
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/* check whether block bitmap block number is set */
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bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
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offset = bitmap_blk - group_first_block;
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if (!ext3_test_bit(offset, bh->b_data))
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/* bad block bitmap */
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goto err_out;
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/* check whether the inode bitmap block number is set */
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bitmap_blk = le32_to_cpu(desc->bg_inode_bitmap);
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offset = bitmap_blk - group_first_block;
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if (!ext3_test_bit(offset, bh->b_data))
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/* bad block bitmap */
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goto err_out;
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/* check whether the inode table block number is set */
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bitmap_blk = le32_to_cpu(desc->bg_inode_table);
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offset = bitmap_blk - group_first_block;
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next_zero_bit = ext3_find_next_zero_bit(bh->b_data,
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offset + EXT3_SB(sb)->s_itb_per_group,
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offset);
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if (next_zero_bit >= offset + EXT3_SB(sb)->s_itb_per_group)
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/* good bitmap for inode tables */
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return 1;
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err_out:
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ext3_error(sb, __FUNCTION__,
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"Invalid block bitmap - "
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"block_group = %d, block = %lu",
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block_group, bitmap_blk);
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return 0;
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}
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/**
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* read_block_bitmap()
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* @sb: super block
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* @block_group: given block group
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*
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* Read the bitmap for a given block_group, reading into the specified
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* slot in the superblock's bitmap cache.
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* Read the bitmap for a given block_group,and validate the
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* bits for block/inode/inode tables are set in the bitmaps
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*
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* Return buffer_head on success or NULL in case of failure.
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*/
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@ -95,17 +139,35 @@ read_block_bitmap(struct super_block *sb, unsigned int block_group)
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{
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struct ext3_group_desc * desc;
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struct buffer_head * bh = NULL;
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ext3_fsblk_t bitmap_blk;
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desc = ext3_get_group_desc (sb, block_group, NULL);
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desc = ext3_get_group_desc(sb, block_group, NULL);
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if (!desc)
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goto error_out;
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bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
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if (!bh)
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ext3_error (sb, "read_block_bitmap",
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return NULL;
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bitmap_blk = le32_to_cpu(desc->bg_block_bitmap);
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bh = sb_getblk(sb, bitmap_blk);
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if (unlikely(!bh)) {
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ext3_error(sb, __FUNCTION__,
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"Cannot read block bitmap - "
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"block_group = %d, block_bitmap = %u",
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block_group, le32_to_cpu(desc->bg_block_bitmap));
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error_out:
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return NULL;
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}
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if (likely(bh_uptodate_or_lock(bh)))
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return bh;
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if (bh_submit_read(bh) < 0) {
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brelse(bh);
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ext3_error(sb, __FUNCTION__,
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"Cannot read block bitmap - "
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"block_group = %d, block_bitmap = %u",
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block_group, le32_to_cpu(desc->bg_block_bitmap));
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return NULL;
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}
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if (!ext3_valid_block_bitmap(sb, desc, block_group, bh)) {
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brelse(bh);
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return NULL;
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}
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return bh;
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}
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/*
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