[PATCH AUTOSEL 4.20 179/304] ipv6: Fix handling of LLA with VRF and sockets bound to VRF

[Sasha Levin]

From: David Ahern <dsahern@xxxxxxxxx>

[ Upstream commit c2027d1e17582903e368abf5d4838b22a98f2b7b ]

A recent commit allows sockets bound to a VRF to receive ipv6 link local
packets. However, it only works for UDP and worse TCP connection attempts
to the LLA with the only listener bound to the VRF just hang where as
before the client gets a reset and connection refused. Fix by adjusting
ir_iif for LL addresses and packets received through a device enslaved
to a VRF.

Fixes: 6f12fa775530 ("vrf: mark skb for multicast or link-local as enslaved to VRF")
Reported-by: Donald Sharp <sharpd@xxxxxxxxxxxxxxxxxxx>
Cc: Mike Manning <mmanning@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David Ahern <dsahern@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/ipv6/tcp_ipv6.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 03e6b7a2bc53..f5c213001b05 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -734,6 +734,7 @@ static void tcp_v6_init_req(struct request_sock *req,
 			    const struct sock *sk_listener,
 			    struct sk_buff *skb)
 {
+	bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
 	struct inet_request_sock *ireq = inet_rsk(req);
 	const struct ipv6_pinfo *np = inet6_sk(sk_listener);
 
@@ -741,7 +742,7 @@ static void tcp_v6_init_req(struct request_sock *req,
 	ireq->ir_v6_loc_addr = ipv6_hdr(skb)->daddr;
 
 	/* So that link locals have meaning */
-	if (!sk_listener->sk_bound_dev_if &&
+	if ((!sk_listener->sk_bound_dev_if || l3_slave) &&
 	    ipv6_addr_type(&ireq->ir_v6_rmt_addr) & IPV6_ADDR_LINKLOCAL)
 		ireq->ir_iif = tcp_v6_iif(skb);
 
-- 
2.19.1