netfilter: disable defrag once its no longer needed

When I changed defrag hooks to no longer get registered by default I
intentionally made it so that registration can only be un-done by unloading
the nf_defrag_ipv4/6 module.

In hindsight this was too conservative; there is no reason to keep defrag
on while there is no feature dependency anymore.

Moreover, this won't work if user isn't allowed to remove nf_defrag module.

This adds the disable() functions for both ipv4 and ipv6 and calls them
from conntrack, TPROXY and the xtables socket module.

ipvs isn't converted here, it will behave as before this patch and
will need module removal.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 24 insertions, 0 deletions

diff --git a/net/netfilter/nft_tproxy.c b/net/netfilter/nft_tproxy.c
index 43a5a780a6d3..accef672088c 100644
--- a/net/netfilter/nft_tproxy.c
+++ b/net/netfilter/nft_tproxy.c
@@ -263,6 +263,29 @@ static int nft_tproxy_init(const struct nft_ctx *ctx,
 	return 0;
 }
 
+static void nft_tproxy_destroy(const struct nft_ctx *ctx,
+			       const struct nft_expr *expr)
+{
+	const struct nft_tproxy *priv = nft_expr_priv(expr);
+
+	switch (priv->family) {
+	case NFPROTO_IPV4:
+		nf_defrag_ipv4_disable(ctx->net);
+		break;
+#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
+	case NFPROTO_IPV6:
+		nf_defrag_ipv6_disable(ctx->net);
+		break;
+#endif
+	case NFPROTO_UNSPEC:
+		nf_defrag_ipv4_disable(ctx->net);
+#if IS_ENABLED(CONFIG_NF_TABLES_IPV6)
+		nf_defrag_ipv6_disable(ctx->net);
+#endif
+		break;
+	}
+}
+
 static int nft_tproxy_dump(struct sk_buff *skb,
 			   const struct nft_expr *expr)
 {
@@ -288,6 +311,7 @@ static const struct nft_expr_ops nft_tproxy_ops = {
 	.size		= NFT_EXPR_SIZE(sizeof(struct nft_tproxy)),
 	.eval		= nft_tproxy_eval,
 	.init		= nft_tproxy_init,
+	.destroy	= nft_tproxy_destroy,
 	.dump		= nft_tproxy_dump,
 };