netfilter: nf_tables: unbind set in rule from commit path

Anonymous sets that are bound to rules from the same transaction trigger
a kernel splat from the abort path due to double set list removal and
double free.

This patch updates the logic to search for the transaction that is
responsible for creating the set and disable the set list removal and
release, given the rule is now responsible for this. Lookup is reverse
since the transaction that adds the set is likely to be at the tail of
the list.

Moreover, this patch adds the unbind step to deliver the event from the
commit path.  This should not be done from the worker thread, since we
have no guarantees of in-order delivery to the listener.

This patch removes the assumption that both activate and deactivate
callbacks need to be provided.

Fixes: cd5125d8f518 ("netfilter: nf_tables: split set destruction in deactivate and destroy phase")
Reported-by: Mikhail Morfikov <mmorfikov@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 7 insertions, 11 deletions

diff --git a/net/netfilter/nft_objref.c b/net/netfilter/nft_objref.c
index a3185ca2a3a9..ae178e914486 100644
--- a/net/netfilter/nft_objref.c
+++ b/net/netfilter/nft_objref.c
@@ -155,20 +155,17 @@ nla_put_failure:
 	return -1;
 }
 
-static void nft_objref_map_activate(const struct nft_ctx *ctx,
-				    const struct nft_expr *expr)
-{
-	struct nft_objref_map *priv = nft_expr_priv(expr);
-
-	nf_tables_rebind_set(ctx, priv->set, &priv->binding);
-}
-
 static void nft_objref_map_deactivate(const struct nft_ctx *ctx,
-				      const struct nft_expr *expr)
+				      const struct nft_expr *expr,
+				      enum nft_trans_phase phase)
 {
 	struct nft_objref_map *priv = nft_expr_priv(expr);
 
-	nf_tables_unbind_set(ctx, priv->set, &priv->binding);
+	if (phase == NFT_TRANS_PREPARE)
+		return;
+
+	nf_tables_unbind_set(ctx, priv->set, &priv->binding,
+			     phase == NFT_TRANS_COMMIT);
 }
 
 static void nft_objref_map_destroy(const struct nft_ctx *ctx,
@@ -185,7 +182,6 @@ static const struct nft_expr_ops nft_objref_map_ops = {
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_objref_map)),
 	.eval		= nft_objref_map_eval,
 	.init		= nft_objref_map_init,
-	.activate	= nft_objref_map_activate,
 	.deactivate	= nft_objref_map_deactivate,
 	.destroy	= nft_objref_map_destroy,
 	.dump		= nft_objref_map_dump,