Merge branch 'xfrm: some fixes for GSO with SW crypto'

Sabrina Dubroca says:

====================
This series fixes a few issues with GSO. Some recent patches made the
incorrect assumption that GSO is only used by offload. The first two
patches in this series restore the old behavior.

The final patch is in the UDP GSO code, but fixes an issue with IPsec
that is currently masked by the lack of GSO for SW crypto. With GSO,
VXLAN over IPsec doesn't get checksummed.
====================

Signed-off-by: Steffen Klassert <[email protected]>

Author: klassert

net/ipv4/udp_offload.c

@@ -217,7 +217,7 @@ static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
 	remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
 	skb->remcsum_offload = remcsum;
 
-	need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb));
+	need_ipsec = (skb_dst(skb) && dst_xfrm(skb_dst(skb))) || skb_sec_path(skb);
 	/* Try to offload checksum if possible */
 	offload_csum = !!(need_csum &&
 			  !need_ipsec &&

net/xfrm/xfrm_device.c

@@ -155,7 +155,8 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur
 		return skb;
 	}
 
-	if (skb_is_gso(skb) && unlikely(xmit_xfrm_check_overflow(skb))) {
+	if (skb_is_gso(skb) && (unlikely(x->xso.dev != dev) ||
+				unlikely(xmit_xfrm_check_overflow(skb)))) {
 		struct sk_buff *segs;
 
 		/* Packet got rerouted, fixup features and segment it. */
@@ -415,10 +416,12 @@ bool xfrm_dev_offload_ok(struct sk_buff *skb, struct xfrm_state *x)
 	struct net_device *dev = x->xso.dev;
 	bool check_tunnel_size;
 
-	if (x->xso.type == XFRM_DEV_OFFLOAD_UNSPECIFIED)
+	if (!x->type_offload ||
+	    (x->xso.type == XFRM_DEV_OFFLOAD_UNSPECIFIED && x->encap))
 		return false;
 
-	if ((dev == xfrm_dst_path(dst)->dev) && !xdst->child->xfrm) {
+	if ((!dev || dev == xfrm_dst_path(dst)->dev) &&
+	    !xdst->child->xfrm) {
 		mtu = xfrm_state_mtu(x, xdst->child_mtu_cached);
 		if (skb->len <= mtu)
 			goto ok;
@@ -430,6 +433,9 @@ bool xfrm_dev_offload_ok(struct sk_buff *skb, struct xfrm_state *x)
 	return false;
 
 ok:
+	if (!dev)
+		return true;
+
 	check_tunnel_size = x->xso.type == XFRM_DEV_OFFLOAD_PACKET &&
 			    x->props.mode == XFRM_MODE_TUNNEL;
 	switch (x->props.family) {