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_dynset.c b/net/netfilter/nft_dynset.c
index 07d4efd3d851..f1172f99752b 100644
--- a/net/netfilter/nft_dynset.c
+++ b/net/netfilter/nft_dynset.c
@@ -235,20 +235,17 @@ err1:
 	return err;
 }
 
-static void nft_dynset_activate(const struct nft_ctx *ctx,
-				const struct nft_expr *expr)
-{
-	struct nft_dynset *priv = nft_expr_priv(expr);
-
-	nf_tables_rebind_set(ctx, priv->set, &priv->binding);
-}
-
 static void nft_dynset_deactivate(const struct nft_ctx *ctx,
-				  const struct nft_expr *expr)
+				  const struct nft_expr *expr,
+				  enum nft_trans_phase phase)
 {
 	struct nft_dynset *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_dynset_destroy(const struct nft_ctx *ctx,
@@ -296,7 +293,6 @@ static const struct nft_expr_ops nft_dynset_ops = {
 	.eval		= nft_dynset_eval,
 	.init		= nft_dynset_init,
 	.destroy	= nft_dynset_destroy,
-	.activate	= nft_dynset_activate,
 	.deactivate	= nft_dynset_deactivate,
 	.dump		= nft_dynset_dump,
 };