netfilter: nft_set_hash: mark set element as dead when deleting from packet path

JIRA: https://issues.redhat.com/browse/RHEL-1720
JIRA: https://issues.redhat.com/browse/RHEL-1721
Upstream Status: commit c92db30
CVE: CVE-2023-4244

commit c92db30
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date:   Wed Aug 9 15:00:06 2023 +0200

    netfilter: nft_set_hash: mark set element as dead when deleting from packet path

    Set on the NFT_SET_ELEM_DEAD_BIT flag on this element, instead of
    performing element removal which might race with an ongoing transaction.
    Enable gc when dynamic flag is set on since dynset deletion requires
    garbage collection after this patch.

    Fixes: d0a8d87 ("netfilter: nft_dynset: support for element deletion")
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Signed-off-by: Florian Westphal <fwestpha@redhat.com>

Author: fw-strlen

net/netfilter/nft_set_hash.c

@@ -249,7 +249,9 @@ static bool nft_rhash_delete(const struct nft_set *set,
 	if (he == NULL)
 		return false;
 
-	return rhashtable_remove_fast(&priv->ht, &he->node, nft_rhash_params) == 0;
+	nft_set_elem_dead(&he->ext);
+
+	return true;
 }
 
 static void nft_rhash_walk(const struct nft_ctx *ctx, struct nft_set *set,
@@ -412,7 +414,7 @@ static int nft_rhash_init(const struct nft_set *set,
 		return err;
 
 	INIT_DEFERRABLE_WORK(&priv->gc_work, nft_rhash_gc);
-	if (set->flags & NFT_SET_TIMEOUT)
+	if (set->flags & (NFT_SET_TIMEOUT | NFT_SET_EVAL))
 		nft_rhash_gc_init(set);
 
 	return 0;