On Thu, Aug 10, 2017 at 02:30:10PM -0700, Eric Sandeen wrote:
> xfs_metadump attempts to zero out unused regions of metadata
> blocks to prevent data leaks when sharing metadata images.
>
> However, Stefan Ring reported a significant number of leaked
> strings when dumping his 1T filesystem. Based on a reduced
> metadata set, I was able to identify "leaf" directories
> (with XFS_DIR2_LEAF1_MAGIC magic) as the primary culprit;
> the region between the end of the entries array and the start
> of the bests array was not getting zeroed out. This patch
> seems to remedy that problem.
>
> Reported-by: Stefan Ring <stefanrin@xxxxxxxxx>
> Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
> ---
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
>
> V2:
>
> - factor into new function, process_dir_leaf_block
> - add DIR3_LEAF1_MAGIC
> - don't add count+stale; count includes stale entries
> - move ltp into code block
>
> diff --git a/db/metadump.c b/db/metadump.c
> index 3967df6..a8756d6 100644
> --- a/db/metadump.c
> +++ b/db/metadump.c
> @@ -1442,6 +1442,37 @@ process_sf_attr(
> }
>
> static void
> +process_dir_leaf_block(
> + char *block)
> +{
> + struct xfs_dir2_leaf *leaf;
> + struct xfs_dir3_icleaf_hdr leafhdr;
> +
> + if (!zero_stale_data)
> + return;
> +
> + /* Yes, this works for dir2 & dir3. Difference is padding. */
> + leaf = (struct xfs_dir2_leaf *)block;
> + M_DIROPS(mp)->leaf_hdr_from_disk(&leafhdr, leaf);
> +
> + /* Zero out space from end of ents[] to bests */
> + if (leafhdr.magic == XFS_DIR2_LEAF1_MAGIC ||
> + leafhdr.magic == XFS_DIR3_LEAF1_MAGIC) {
> + struct xfs_dir2_leaf_tail *ltp;
> + __be16 *lbp;
> + struct xfs_dir2_leaf_entry *ents;
> + char *free; /* end of ents */
> +
> + ents = M_DIROPS(mp)->leaf_ents_p(leaf);
> + free = (char *)&ents[leafhdr.count];
> + ltp = xfs_dir2_leaf_tail_p(mp->m_dir_geo, leaf);
> + lbp = xfs_dir2_leaf_bests_p(ltp);
> + memset(free, 0, (char *)lbp - free);
> + iocur_top->need_crc = 1;
> + }
> +}
> +
> +static void
> process_dir_data_block(
> char *block,
> xfs_fileoff_t offset,
> @@ -1801,11 +1832,15 @@ process_single_fsb_objects(
> dp = iocur_top->data;
> switch (btype) {
> case TYP_DIR2:
> - if (o >= mp->m_dir_geo->leafblk)
> + if (o >= mp->m_dir_geo->freeblk) {
> + /* TODO, zap any stale data */
> break;
> -
> - process_dir_data_block(dp, o,
> + } else if (o >= mp->m_dir_geo->leafblk) {
> + process_dir_leaf_block(dp);
> + } else {
> + process_dir_data_block(dp, o,
> last == mp->m_dir_geo->fsbcount);
> + }
> iocur_top->need_crc = 1;
> break;
> case TYP_SYMLINK:
>
> --
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