wireguard: receive: use tunnel helpers for decapsulating ECN markings

WireGuard currently only propagates ECN markings on tunnel decap according
to the old RFC3168 specification. However, the spec has since been updated
in RFC6040 to recommend slightly different decapsulation semantics. This
was implemented in the kernel as a set of common helpers for ECN
decapsulation, so let's just switch over WireGuard to using those, so it
can benefit from this enhancement and any future tweaks. We do not drop
packets with invalid ECN marking combinations, because WireGuard is
frequently used to work around broken ISPs, which could be doing that.

Fixes: e7096c131e ("net: WireGuard secure network tunnel")
Reported-by: Olivier Tilmans <olivier.tilmans@nokia-bell-labs.com>
Cc: Dave Taht <dave.taht@gmail.com>
Cc: Rodney W. Grimes <ietf@gndrsh.dnsmgr.net>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Toke Høiland-Jørgensen 2020-04-29 14:59:22 -06:00 committed by David S. Miller
parent 130c586061
commit eebabcb26e

View File

@ -393,13 +393,11 @@ static void wg_packet_consume_data_done(struct wg_peer *peer,
len = ntohs(ip_hdr(skb)->tot_len);
if (unlikely(len < sizeof(struct iphdr)))
goto dishonest_packet_size;
if (INET_ECN_is_ce(PACKET_CB(skb)->ds))
IP_ECN_set_ce(ip_hdr(skb));
INET_ECN_decapsulate(skb, PACKET_CB(skb)->ds, ip_hdr(skb)->tos);
} else if (skb->protocol == htons(ETH_P_IPV6)) {
len = ntohs(ipv6_hdr(skb)->payload_len) +
sizeof(struct ipv6hdr);
if (INET_ECN_is_ce(PACKET_CB(skb)->ds))
IP6_ECN_set_ce(skb, ipv6_hdr(skb));
INET_ECN_decapsulate(skb, PACKET_CB(skb)->ds, ipv6_get_dsfield(ipv6_hdr(skb)));
} else {
goto dishonest_packet_type;
}