xfrm: Provide private skb extensions for segmented and hw offloaded ESP packets

Commit 94579ac3 ("xfrm: Fix double ESP trailer insertion in IPsec
crypto offload.") added a XFRM_XMIT flag to avoid duplicate ESP trailer
insertion on HW offload. This flag is set on the secpath that is shared
amongst segments. This lead to a situation where some segments are
not transformed correctly when segmentation happens at layer 3.

Fix this by using private skb extensions for segmented and hw offloaded
ESP packets.

Fixes: 94579ac3 ("xfrm: Fix double ESP trailer insertion in IPsec crypto offload.")
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

net/ipv4/esp4_offload.c

@@ -314,8 +314,17 @@ static int esp_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features_
 	ip_hdr(skb)->tot_len = htons(skb->len);
 	ip_send_check(ip_hdr(skb));
 
-	if (hw_offload)
+	if (hw_offload) {
+		if (!skb_ext_add(skb, SKB_EXT_SEC_PATH))
+			return -ENOMEM;
+
+		xo = xfrm_offload(skb);
+		if (!xo)
+			return -EINVAL;
+
+		xo->flags |= XFRM_XMIT;
 		return 0;
+	}
 
 	err = esp_output_tail(x, skb, &esp);
 	if (err)

net/ipv6/esp6_offload.c

@@ -348,8 +348,17 @@ static int esp6_xmit(struct xfrm_state *x, struct sk_buff *skb,  netdev_features
 
 	ipv6_hdr(skb)->payload_len = htons(len);
 
-	if (hw_offload)
+	if (hw_offload) {
+		if (!skb_ext_add(skb, SKB_EXT_SEC_PATH))
+			return -ENOMEM;
+
+		xo = xfrm_offload(skb);
+		if (!xo)
+			return -EINVAL;
+
+		xo->flags |= XFRM_XMIT;
 		return 0;
+	}
 
 	err = esp6_output_tail(x, skb, &esp);
 	if (err)

net/xfrm/xfrm_device.c

@@ -134,8 +134,6 @@ struct sk_buff *validate_xmit_xfrm(struct sk_buff *skb, netdev_features_t featur
 		return skb;
 	}
 
-	xo->flags |= XFRM_XMIT;
-
 	if (skb_is_gso(skb) && unlikely(x->xso.dev != dev)) {
 		struct sk_buff *segs;