xfrm: Fix inner mode lookup in tunnel mode GSO segmentation

Commit 61fafbee6cfe ("xfrm: Determine inner GSO type from packet inner
protocol") attempted to fix GSO segmentation by reading the inner
protocol from XFRM_MODE_SKB_CB(skb)->protocol. This was incorrect
because the field holds the inner L4 protocol (TCP/UDP) instead of the
required tunnel protocol. Also, the memory location (shared by
XFRM_SKB_CB(skb) which could be overwritten by xfrm_replay_overflow())
is prone to corruption. This combination caused the kernel to select
the wrong inner mode and get the wrong address family.

The correct value is in xfrm_offload(skb)->proto, which is set from
the outer tunnel header's protocol field by esp[4|6]_gso_encap(). It
is initialized by xfrm[4|6]_tunnel_encap_add() to either IPPROTO_IPIP
or IPPROTO_IPV6, using xfrm_af2proto() and correctly reflects the
inner packet's address family.

Fixes: 61fafbee6cfe ("xfrm: Determine inner GSO type from packet inner protocol")
Signed-off-by: Jianbo Liu <jianbol@nvidia.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

diff --git a/net/ipv4/esp4_offload.c b/net/ipv4/esp4_offload.c
index 05828d4cb6cdbbad8cf2e67718eefe6101d31cd9..abd77162f5e75ec01d5e66693f20a80a78af9e50 100644 (file)
--- a/net/ipv4/esp4_offload.c
+++ b/net/ipv4/esp4_offload.c
@@ -122,8 +122,8 @@ static struct sk_buff *xfrm4_tunnel_gso_segment(struct xfrm_state *x,
                                                struct sk_buff *skb,
                                                netdev_features_t features)
 {
-       const struct xfrm_mode *inner_mode = xfrm_ip2inner_mode(x,
-                                       XFRM_MODE_SKB_CB(skb)->protocol);
+       struct xfrm_offload *xo = xfrm_offload(skb);
+       const struct xfrm_mode *inner_mode = xfrm_ip2inner_mode(x, xo->proto);
        __be16 type = inner_mode->family == AF_INET6 ? htons(ETH_P_IPV6)
                                                     : htons(ETH_P_IP);
 

diff --git a/net/ipv6/esp6_offload.c b/net/ipv6/esp6_offload.c
index 22410243ebe88dbd2931be9b53bb2d49239e2a5b..22895521a57d09acfe091927f20188764f33f91b 100644 (file)
--- a/net/ipv6/esp6_offload.c
+++ b/net/ipv6/esp6_offload.c
@@ -158,8 +158,8 @@ static struct sk_buff *xfrm6_tunnel_gso_segment(struct xfrm_state *x,
                                                struct sk_buff *skb,
                                                netdev_features_t features)
 {
-       const struct xfrm_mode *inner_mode = xfrm_ip2inner_mode(x,
-                                       XFRM_MODE_SKB_CB(skb)->protocol);
+       struct xfrm_offload *xo = xfrm_offload(skb);
+       const struct xfrm_mode *inner_mode = xfrm_ip2inner_mode(x, xo->proto);
        __be16 type = inner_mode->family == AF_INET ? htons(ETH_P_IP)
                                                    : htons(ETH_P_IPV6);