[PATCH v3 net 2/3] net: always dissect GSO packets in __virtio_net_hdr_to_skb()

@@ -209,6 +209,7 @@ static int raw_verify_header(
 	if ((vheader->flags & VIRTIO_NET_HDR_F_DATA_VALID) > 0)
 		return 1;
 
+	skb_set_network_header(skb, ETH_HLEN);
 	virtio_net_hdr_to_skb(skb, vheader, virtio_legacy_is_little_endian());
 	return 0;
 }

@@ -1897,12 +1897,7 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 		}
 	}
 
-	if (tun_vnet_hdr_tnl_to_skb(tun->flags, features, skb, &hdr)) {
-		atomic_long_inc(&tun->rx_frame_errors);
-		err = -EINVAL;
-		goto free_skb;
-	}
-
+	skb->dev = tun->dev;
 	switch (tun->flags & TUN_TYPE_MASK) {
 	case IFF_TUN:
 		if (tun->flags & IFF_NO_PI) {

@@ -1927,9 +1922,8 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 			}
 		}
 
-		skb_reset_mac_header(skb);
+		skb_reset_network_header(skb);
 		skb->protocol = pi.proto;
-		skb->dev = tun->dev;
 		break;
 	case IFF_TAP:
 		if (!pskb_may_pull(skb, ETH_HLEN)) {

@@ -1937,10 +1931,19 @@ static ssize_t tun_get_user(struct tun_struct *tun, struct tun_file *tfile,
 			drop_reason = SKB_DROP_REASON_HDR_TRUNC;
 			goto drop;
 		}
-		skb->protocol = eth_type_trans(skb, tun->dev);
+		skb_set_network_header(skb, ETH_HLEN);
 		break;
 	}
 
+	if (tun_vnet_hdr_tnl_to_skb(tun->flags, features, skb, &hdr)) {
+		atomic_long_inc(&tun->rx_frame_errors);
+		err = -EINVAL;
+		goto free_skb;
+	}
+
+	if ((tun->flags & TUN_TYPE_MASK) == IFF_TAP)
+		skb->protocol = eth_type_trans(skb, tun->dev);
+
 	/* copy skb_ubuf_info for callback when skb has no error */
 	if (zerocopy) {
 		skb_zcopy_init(skb, msg_control);

@@ -2600,6 +2603,8 @@ static int tun_xdp_one(struct tun_struct *tun,
 
 	features = tun_vnet_hdr_guest_features(READ_ONCE(tun->vnet_hdr_sz));
 	tnl_hdr = (struct virtio_net_hdr_v1_hash_tunnel *)gso;
+	skb->dev = tun->dev;
+	skb_set_network_header(skb, ETH_HLEN);
 	if (tun_vnet_hdr_tnl_to_skb(tun->flags, features, skb, tnl_hdr)) {
 		atomic_long_inc(&tun->rx_frame_errors);
 		kfree_skb(skb);

@@ -2515,6 +2515,8 @@ static void virtnet_receive_done(struct virtnet_info *vi, struct receive_queue *
 		goto frame_err;
 	}
 
+	skb->dev = dev;
+	skb_set_network_header(skb, ETH_HLEN);
 	if (virtio_net_hdr_tnl_to_skb(skb, &hdr->tnl_hdr, vi->rx_tnl,
 				      vi->rx_tnl_csum,
 				      virtio_is_little_endian(vi->vdev))) {

@@ -111,48 +111,38 @@ static inline int __virtio_net_hdr_to_skb(struct sk_buff *skb,
 		p_off = nh_min_len + thlen;
 		if (!pskb_may_pull(skb, p_off))
 			return -EINVAL;
-	} else {
+	} else if (gso_type) {
 		/* gso packets without NEEDS_CSUM do not set transport_offset.
 		 * probe and drop if does not match one of the above types.
 		 */
-		if (gso_type && skb->network_header) {
-			struct flow_keys_basic keys;
-
-			if (!skb->protocol) {
-				__be16 protocol = dev_parse_header_protocol(skb);
-
-				if (!protocol)
-					virtio_net_hdr_set_proto(skb, hdr);
-				else if (!virtio_net_hdr_match_proto(protocol,
-								 hdr_gso_type))
-					return -EINVAL;
-				else
-					skb->protocol = protocol;
-			}
+		struct flow_keys_basic keys;
+
+		if (!skb->protocol) {
+			skb->protocol = dev_parse_header_protocol(skb);
+			if (!skb->protocol)
+				virtio_net_hdr_set_proto(skb, hdr);
+		}
 retry:
-			if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,
-							      NULL, 0, 0, 0,
-							      0)) {
-				/* UFO does not specify ipv4 or 6: try both */
-				if (gso_type & SKB_GSO_UDP &&
-				    skb->protocol == htons(ETH_P_IP)) {
-					skb->protocol = htons(ETH_P_IPV6);
-					goto retry;
-				}
-				return -EINVAL;
+		if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,
+						      NULL, 0, 0, 0,
+						      0)) {
+			/* UFO does not specify ipv4 or 6: try both */
+			if (gso_type & SKB_GSO_UDP &&
+			    skb->protocol == htons(ETH_P_IP)) {
+				skb->protocol = htons(ETH_P_IPV6);
+				goto retry;
 			}
+			return -EINVAL;
+		}
 
-			p_off = keys.control.thoff + thlen;
-			if (!pskb_may_pull(skb, p_off) ||
-			    keys.basic.ip_proto != ip_proto)
-				return -EINVAL;
+		p_off = keys.control.thoff + thlen;
+		if (!pskb_may_pull(skb, p_off) ||
+		    keys.basic.ip_proto != ip_proto ||
+		    !virtio_net_hdr_match_proto(keys.basic.n_proto,
+						hdr_gso_type))
+			return -EINVAL;
 
-			skb_set_transport_header(skb, keys.control.thoff);
-		} else if (gso_type) {
-			p_off = nh_min_len + thlen;
-			if (!pskb_may_pull(skb, p_off))
-				return -EINVAL;
-		}
+		skb_set_transport_header(skb, keys.control.thoff);
 	}
 
 	if (hdr_gso_type != VIRTIO_NET_HDR_GSO_NONE) {