ipv6: Consolidate route lookup sequences.

Route lookups follow a general pattern in the ipv6 code wherein
we first find the non-IPSEC route, potentially override the
flow destination address due to ipv6 options settings, and then
finally make an IPSEC search using either xfrm_lookup() or
__xfrm_lookup().

__xfrm_lookup() is used when we want to generate a blackhole route
if the key manager needs to resolve the IPSEC rules (in this case
-EREMOTE is returned and the original 'dst' is left unchanged).

Otherwise plain xfrm_lookup() is used and when asynchronous IPSEC
resolution is necessary, we simply fail the lookup completely.

All of these cases are encapsulated into two routines,
ip6_dst_lookup_flow and ip6_sk_dst_lookup_flow.  The latter of which
handles unconnected UDP datagram sockets.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 11 deletions

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index a419a78..d86d7f6 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -1125,18 +1125,11 @@ do_udp_sendmsg:
 
 	security_sk_classify_flow(sk, &fl);
 
-	err = ip6_sk_dst_lookup(sk, &dst, &fl);
-	if (err)
+	dst = ip6_sk_dst_lookup_flow(sk, &fl, final_p, true);
+	if (IS_ERR(dst)) {
+		err = PTR_ERR(dst);
+		dst = NULL;
 		goto out;
-	if (final_p)
-		ipv6_addr_copy(&fl.fl6_dst, final_p);
-
-	err = __xfrm_lookup(sock_net(sk), &dst, &fl, sk, XFRM_LOOKUP_WAIT);
-	if (err < 0) {
-		if (err == -EREMOTE)
-			err = ip6_dst_blackhole(sk, &dst, &fl);
-		if (err < 0)
-			goto out;
 	}
 
 	if (hlimit < 0) {