Commit b40c5f4f authored Apr 21, 2017 by Ansis Atteka Committed by David S. Miller Apr 24, 2017

udp: disable inner UDP checksum offloads in IPsec case



Otherwise, UDP checksum offloads could corrupt ESP packets by attempting
to calculate UDP checksum when this inner UDP packet is already protected
by IPsec.

One way to reproduce this bug is to have a VM with virtio_net driver (UFO
set to ON in the guest VM); and then encapsulate all guest's Ethernet
frames in Geneve; and then further encrypt Geneve with IPsec.  In this
case following symptoms are observed:
1. If using ixgbe NIC, then it will complain with following error message:
   ixgbe 0000:01:00.1: partial checksum but l4 proto=32!
2. Receiving IPsec stack will drop all the corrupted ESP packets and
   increase XfrmInStateProtoError counter in /proc/net/xfrm_stat.
3. iperf UDP test from the VM with packet sizes above MTU will not work at
   all.
4. iperf TCP test from the VM will get ridiculously low performance because.

Signed-off-by: Ansis Atteka <aatteka@ovn.org>
Co-authored-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 4d6fa57b

net/ipv4/udp_offload.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -29,6 +29,7 @@ static struct sk_buff __skb_udp_tunnel_segment(struct sk_buff skb,
		u16 mac_len = skb->mac_len;
		int udp_offset, outer_hlen;
		__wsum partial;
		bool need_ipsec;

		if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
		goto out;
		@@ -62,8 +63,10 @@ static struct sk_buff __skb_udp_tunnel_segment(struct sk_buff skb,

		ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);

		need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb));
		/* Try to offload checksum if possible */
		offload_csum = !!(need_csum &&
		!need_ipsec &&
		(skb->dev->features &
		(is_ipv6 ? (NETIF_F_HW_CSUM \| NETIF_F_IPV6_CSUM) :
		(NETIF_F_HW_CSUM \| NETIF_F_IP_CSUM))));

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