On Tue, Aug 01, 2017 at 09:35:27PM -0500, 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>
> ---
>
> I may have missed some handy macro to work out some of the
> math below, if so I'd be perfectly happy to hear about it ;)
>
Looks good to me. A couple nits...
> diff --git a/db/metadump.c b/db/metadump.c
> index 96641e0..6d77d61 100644
> --- a/db/metadump.c
> +++ b/db/metadump.c
> @@ -1459,6 +1459,37 @@ process_dir_data_block(
> int wantmagic;
> struct xfs_dir2_data_hdr *datahdr;
>
> + if (offset >= mp->m_dir_geo->freeblk) {
> + /* TODO */
> + return;
TODO what exactly? Zero from the end of the bests array to the end of
the block? We could at least add the if (!zero_stale_data) check here
too.
> + } else if (offset >= mp->m_dir_geo->leafblk) {
> + struct xfs_dir2_leaf *leaf;
> + struct xfs_dir2_leaf_tail *ltp;
> + struct xfs_dir3_icleaf_hdr leafhdr;
> +
> + if (!zero_stale_data)
> + return;
> +
> + leaf = (struct xfs_dir2_leaf *)block;
> + ltp = xfs_dir2_leaf_tail_p(mp->m_dir_geo, leaf);
ltp isn't used until the block of code below (which already has locally
scoped vars).
Brian
> + 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) {
> + struct xfs_dir2_leaf_entry *ents;
> + __be16 *lbp;
> + char *start; /* end of ents */
> +
> + ents = M_DIROPS(mp)->leaf_ents_p(leaf);
> + start = (char *)&ents[leafhdr.count + leafhdr.stale];
> + lbp = xfs_dir2_leaf_bests_p(ltp);
> + memset(start, 0, (char *)lbp - start);
> + iocur_top->need_crc = 1;
> + }
> + return;
> + }
> +
> + /* It's a data block. */
> datahdr = (struct xfs_dir2_data_hdr *)block;
>
> if (is_block_format) {
> @@ -1800,9 +1831,6 @@ process_single_fsb_objects(
> dp = iocur_top->data;
> switch (btype) {
> case TYP_DIR2:
> - if (o >= mp->m_dir_geo->leafblk)
> - break;
> -
> process_dir_data_block(dp, o,
> last == mp->m_dir_geo->fsbcount);
> iocur_top->need_crc = 1;
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
