ila: Perform only one translation in forwarding path

When setting up ILA in a router we noticed that the the encapsulation
is invoked twice: once in the route input path and again upon route
output. To resolve this we add a flag set_csum_neutral for the
ila_update_ipv6_locator. If this flag is set and the checksum
neutral bit is also set we assume that checksum-neutral translation
has already been performed and take no further action. The
flag is set only in ila_output path. The flag is not set for ila_input and
ila_xlat.

Tested:

Used 3 netns to set to emulate a router and two hosts. The router
translates SIR addresses between the two destinations in other two netns.
Verified ping and netperf are functional.

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

1 files changed, 4 insertions, 4 deletions

diff --git a/net/ipv6/ila/ila_xlat.c b/net/ipv6/ila/ila_xlat.c
index a90e57229c6c..e6eca5fdf4c9 100644
--- a/net/ipv6/ila/ila_xlat.c
+++ b/net/ipv6/ila/ila_xlat.c
@@ -210,14 +210,14 @@ static void ila_free_cb(void *ptr, void *arg)
 	}
 }
 
-static int ila_xlat_addr(struct sk_buff *skb);
+static int ila_xlat_addr(struct sk_buff *skb, bool set_csum_neutral);
 
 static unsigned int
 ila_nf_input(void *priv,
 	     struct sk_buff *skb,
 	     const struct nf_hook_state *state)
 {
-	ila_xlat_addr(skb);
+	ila_xlat_addr(skb, false);
 	return NF_ACCEPT;
 }
 
@@ -597,7 +597,7 @@ static struct pernet_operations ila_net_ops = {
 	.size = sizeof(struct ila_net),
 };
 
-static int ila_xlat_addr(struct sk_buff *skb)
+static int ila_xlat_addr(struct sk_buff *skb, bool set_csum_neutral)
 {
 	struct ila_map *ila;
 	struct ipv6hdr *ip6h = ipv6_hdr(skb);
@@ -616,7 +616,7 @@ static int ila_xlat_addr(struct sk_buff *skb)
 
 	ila = ila_lookup_wildcards(iaddr, skb->dev->ifindex, ilan);
 	if (ila)
-		ila_update_ipv6_locator(skb, &ila->xp.ip);
+		ila_update_ipv6_locator(skb, &ila->xp.ip, set_csum_neutral);
 
 	rcu_read_unlock();