netdev - [PATCH bpf-next 1/2] bpf: update skb->protocol in bpf_skb_net

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Message-Id: <20190422145059.125561-2-willemdebruijn.kernel@gmail.com>
Date:   Mon, 22 Apr 2019 10:50:58 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     netdev@...r.kernel.org
Cc:     ast@...nel.org, daniel@...earbox.net, alan.maguire@...cle.com,
        Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH bpf-next 1/2] bpf: update skb->protocol in bpf_skb_net_grow

From: Willem de Bruijn <willemb@...gle.com>

Some tunnels, like sit, change the network protocol of packet.
If so, update skb->protocol to match the new type.

Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
 net/core/filter.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/core/filter.c b/net/core/filter.c
index 1833926a63fc1..bd4d498fabfa4 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -3047,6 +3047,14 @@ static int bpf_skb_net_grow(struct sk_buff *skb, u32 off, u32 len_diff,
 
 			skb_set_transport_header(skb, mac_len + nh_len);
 		}
+
+		/* Match skb->protocol to new outer l3 protocol */
+		if (skb->protocol == htons(ETH_P_IP) &&
+		    flags & BPF_F_ADJ_ROOM_ENCAP_L3_IPV6)
+			skb->protocol = htons(ETH_P_IPV6);
+		else if (skb->protocol == htons(ETH_P_IPV6) &&
+			 flags & BPF_F_ADJ_ROOM_ENCAP_L3_IPV4)
+			skb->protocol = htons(ETH_P_IP);
 	}
 
 	if (skb_is_gso(skb)) {
-- 
2.21.0.593.g511ec345e18-goog