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Commit 7a7ffbab authored by Wei-Chun Chao's avatar Wei-Chun Chao Committed by David S. Miller
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ipv4: fix tunneled VM traffic over hw VXLAN/GRE GSO NIC 



VM to VM GSO traffic is broken if it goes through VXLAN or GRE
tunnel and the physical NIC on the host supports hardware VXLAN/GRE
GSO offload (e.g. bnx2x and next-gen mlx4).

Two issues -
(VXLAN) VM traffic has SKB_GSO_DODGY and SKB_GSO_UDP_TUNNEL with
SKB_GSO_TCP/UDP set depending on the inner protocol. GSO header
integrity check fails in udp4_ufo_fragment if inner protocol is
TCP. Also gso_segs is calculated incorrectly using skb->len that
includes tunnel header. Fix: robust check should only be applied
to the inner packet.

(VXLAN & GRE) Once GSO header integrity check passes, NULL segs
is returned and the original skb is sent to hardware. However the
tunnel header is already pulled. Fix: tunnel header needs to be
restored so that hardware can perform GSO properly on the original
packet.

Signed-off-by: default avatarWei-Chun Chao <weichunc@plumgrid.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 619a60ee

include/linux/netdevice.h

+13 −0
Original line number Diff line number Diff line
@@ -3017,6 +3017,19 @@ static inline void netif_set_gso_max_size(struct net_device *dev, 
	dev->gso_max_size = size;

}



static inline void skb_gso_error_unwind(struct sk_buff *skb, __be16 protocol,

					int pulled_hlen, u16 mac_offset,

					int mac_len)

{

	skb->protocol = protocol;

	skb->encapsulation = 1;

	skb_push(skb, pulled_hlen);

	skb_reset_transport_header(skb);

	skb->mac_header = mac_offset;

	skb->network_header = skb->mac_header + mac_len;

	skb->mac_len = mac_len;

}



static inline bool netif_is_macvlan(struct net_device *dev)

{

	return dev->priv_flags & IFF_MACVLAN;

net/ipv4/gre_offload.c

+7 −4
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb, 
	netdev_features_t enc_features;

	int ghl = GRE_HEADER_SECTION;

	struct gre_base_hdr *greh;

	u16 mac_offset = skb->mac_header;

	int mac_len = skb->mac_len;

	__be16 protocol = skb->protocol;

	int tnl_hlen;
@@ -58,13 +59,13 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb, 
	} else

		csum = false;



	if (unlikely(!pskb_may_pull(skb, ghl)))

		goto out;



	/* setup inner skb. */

	skb->protocol = greh->protocol;

	skb->encapsulation = 0;



	if (unlikely(!pskb_may_pull(skb, ghl)))

		goto out;



	__skb_pull(skb, ghl);

	skb_reset_mac_header(skb);

	skb_set_network_header(skb, skb_inner_network_offset(skb));
@@ -73,8 +74,10 @@ static struct sk_buff *gre_gso_segment(struct sk_buff *skb, 
	/* segment inner packet. */

	enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);

	segs = skb_mac_gso_segment(skb, enc_features);

	if (!segs || IS_ERR(segs))

	if (!segs || IS_ERR(segs)) {

		skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);

		goto out;

	}



	skb = segs;

	tnl_hlen = skb_tnl_header_len(skb);

net/ipv4/udp.c

+5 −1
Original line number Diff line number Diff line
@@ -2478,6 +2478,7 @@ struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb, 
				       netdev_features_t features)

{

	struct sk_buff *segs = ERR_PTR(-EINVAL);

	u16 mac_offset = skb->mac_header;

	int mac_len = skb->mac_len;

	int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);

	__be16 protocol = skb->protocol;
@@ -2497,8 +2498,11 @@ struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb, 
	/* segment inner packet. */

	enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);

	segs = skb_mac_gso_segment(skb, enc_features);

	if (!segs || IS_ERR(segs))

	if (!segs || IS_ERR(segs)) {

		skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,

				     mac_len);

		goto out;

	}



	outer_hlen = skb_tnl_header_len(skb);

	skb = segs;

net/ipv4/udp_offload.c

+19 −18
Original line number Diff line number Diff line
@@ -41,6 +41,14 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, 
{

	struct sk_buff *segs = ERR_PTR(-EINVAL);

	unsigned int mss;

	int offset;

	__wsum csum;



	if (skb->encapsulation &&

	    skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL) {

		segs = skb_udp_tunnel_segment(skb, features);

		goto out;

	}



	mss = skb_shinfo(skb)->gso_size;

	if (unlikely(skb->len <= mss))
@@ -63,15 +71,6 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, 
		goto out;

	}



	/* Fragment the skb. IP headers of the fragments are updated in

	 * inet_gso_segment()

	 */

	if (skb->encapsulation && skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL)

		segs = skb_udp_tunnel_segment(skb, features);

	else {

		int offset;

		__wsum csum;



	/* Do software UFO. Complete and fill in the UDP checksum as

	 * HW cannot do checksum of UDP packets sent as multiple

	 * IP fragments.
@@ -82,8 +81,10 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb, 
	*(__sum16 *)(skb->data + offset) = csum_fold(csum);

	skb->ip_summed = CHECKSUM_NONE;



	/* Fragment the skb. IP headers of the fragments are updated in

	 * inet_gso_segment()

	 */

	segs = skb_segment(skb, features);

	}

out:

	return segs;

}