lwt: Add support to redirect dst.input

This patch adds the capability to redirect dst input in the same way
that dst output is redirected by LWT.

Also, save the original dst.input and and dst.out when setting up
lwtunnel redirection. These can be called by the client as a pass-
through.

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 69 insertions, 2 deletions

diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
index 5d6d8e3d450a..3331585174d9 100644
--- a/net/core/lwtunnel.c
+++ b/net/core/lwtunnel.c
@@ -241,3 +241,58 @@ int lwtunnel_output(struct sock *sk, struct sk_buff *skb)
 	return __lwtunnel_output(sk, skb, lwtstate);
 }
 EXPORT_SYMBOL(lwtunnel_output);
+
+int __lwtunnel_input(struct sk_buff *skb,
+		     struct lwtunnel_state *lwtstate)
+{
+	const struct lwtunnel_encap_ops *ops;
+	int ret = -EINVAL;
+
+	if (!lwtstate)
+		goto drop;
+
+	if (lwtstate->type == LWTUNNEL_ENCAP_NONE ||
+	    lwtstate->type > LWTUNNEL_ENCAP_MAX)
+		return 0;
+
+	ret = -EOPNOTSUPP;
+	rcu_read_lock();
+	ops = rcu_dereference(lwtun_encaps[lwtstate->type]);
+	if (likely(ops && ops->input))
+		ret = ops->input(skb);
+	rcu_read_unlock();
+
+	if (ret == -EOPNOTSUPP)
+		goto drop;
+
+	return ret;
+
+drop:
+	kfree_skb(skb);
+
+	return ret;
+}
+
+int lwtunnel_input6(struct sk_buff *skb)
+{
+	struct rt6_info *rt = (struct rt6_info *)skb_dst(skb);
+	struct lwtunnel_state *lwtstate = NULL;
+
+	if (rt)
+		lwtstate = rt->rt6i_lwtstate;
+
+	return __lwtunnel_input(skb, lwtstate);
+}
+EXPORT_SYMBOL(lwtunnel_input6);
+
+int lwtunnel_input(struct sk_buff *skb)
+{
+	struct rtable *rt = (struct rtable *)skb_dst(skb);
+	struct lwtunnel_state *lwtstate = NULL;
+
+	if (rt)
+		lwtstate = rt->rt_lwtstate;
+
+	return __lwtunnel_input(skb, lwtstate);
+}
+EXPORT_SYMBOL(lwtunnel_input);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 2c89d294b669..2403e85107f0 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -1631,8 +1631,14 @@ static int __mkroute_input(struct sk_buff *skb,
 	rth->dst.output = ip_output;
 
 	rt_set_nexthop(rth, daddr, res, fnhe, res->fi, res->type, itag);
-	if (lwtunnel_output_redirect(rth->rt_lwtstate))
+	if (lwtunnel_output_redirect(rth->rt_lwtstate)) {
+		rth->rt_lwtstate->orig_output = rth->dst.output;
 		rth->dst.output = lwtunnel_output;
+	}
+	if (lwtunnel_input_redirect(rth->rt_lwtstate)) {
+		rth->rt_lwtstate->orig_input = rth->dst.input;
+		rth->dst.input = lwtunnel_input;
+	}
 	skb_dst_set(skb, &rth->dst);
 out:
 	err = 0;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 1c0217e61357..c3733049715e 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1785,8 +1785,14 @@ int ip6_route_add(struct fib6_config *cfg)
 		if (err)
 			goto out;
 		rt->rt6i_lwtstate = lwtstate_get(lwtstate);
-		if (lwtunnel_output_redirect(rt->rt6i_lwtstate))
+		if (lwtunnel_output_redirect(rt->rt6i_lwtstate)) {
+			rt->rt6i_lwtstate->orig_output = rt->dst.output;
 			rt->dst.output = lwtunnel_output6;
+		}
+		if (lwtunnel_input_redirect(rt->rt6i_lwtstate)) {
+			rt->rt6i_lwtstate->orig_input = rt->dst.input;
+			rt->dst.input = lwtunnel_input6;
+		}
 	}
 
 	ipv6_addr_prefix(&rt->rt6i_dst.addr, &cfg->fc_dst, cfg->fc_dst_len);