netfilter: nf_tables: skip dead set elements in netlink dump

Delete from packet path relies on the garbage collector to purge
elements with NFT_SET_ELEM_DEAD_BIT on.

Skip these dead elements from nf_tables_dump_setelem() path, I very
rarely see tests/shell/testcases/maps/typeof_maps_add_delete reports
[DUMP FAILED] showing a mismatch in the expected output with an element
that should not be there.

If the netlink dump happens before GC worker run, it might show dead
elements in the ruleset listing.

nft_rhash_get() already skips dead elements in nft_rhash_cmp(),
therefore, it already does not show the element when getting a single
element via netlink control plane.

Fixes: 5f68718b34a5 ("netfilter: nf_tables: GC transaction API to avoid race with control plane")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index e9fa4a32c09394a4b5b12b5577c36b04c3c9da52..88a6a858383b61fd8d45df47ad9c40696e6ab2bb 100644 (file)
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5718,7 +5718,7 @@ static int nf_tables_dump_setelem(const struct nft_ctx *ctx,
        const struct nft_set_ext *ext = nft_set_elem_ext(set, elem_priv);
        struct nft_set_dump_args *args;
 
-       if (nft_set_elem_expired(ext))
+       if (nft_set_elem_expired(ext) || nft_set_elem_is_dead(ext))
                return 0;
 
        args = container_of(iter, struct nft_set_dump_args, iter);