net: accept UFOv6 packages in virtio_net_hdr_to_skb

Skb with skb->protocol 0 at the time of virtio_net_hdr_to_skb may have
a protocol inferred from virtio_net_hdr with virtio_net_hdr_set_proto.

Unlike TCP, UDP does not have separate types for IPv4 and IPv6. Type
VIRTIO_NET_HDR_GSO_UDP is guessed to be IPv4/UDP. As of the below
commit, UFOv6 packets are dropped due to not matching the protocol as
obtained from dev_parse_header_protocol.

Invert the test to take that L2 protocol field as starting point and
pass both UFOv4 and UFOv6 for VIRTIO_NET_HDR_GSO_UDP.

Fixes: 924a9bc362a5 ("net: check if protocol extracted by virtio_net_hdr_set_proto is correct")
Link: https://lore.kernel.org/netdev/CABcq3pG9GRCYqFDBAJ48H1vpnnX=41u+MhQnayF1ztLH4WX0Fw@mail.gmail.com/
Reported-by: Andrew Melnichenko <andrew@daynix.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20211220144901.2784030-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index 04e87f4..22dd48c 100644 (file)
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -7,6 +7,21 @@
 #include <uapi/linux/udp.h>
 #include <uapi/linux/virtio_net.h>
 
+static inline bool virtio_net_hdr_match_proto(__be16 protocol, __u8 gso_type)
+{
+       switch (gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
+       case VIRTIO_NET_HDR_GSO_TCPV4:
+               return protocol == cpu_to_be16(ETH_P_IP);
+       case VIRTIO_NET_HDR_GSO_TCPV6:
+               return protocol == cpu_to_be16(ETH_P_IPV6);
+       case VIRTIO_NET_HDR_GSO_UDP:
+               return protocol == cpu_to_be16(ETH_P_IP) ||
+                      protocol == cpu_to_be16(ETH_P_IPV6);
+       default:
+               return false;
+       }
+}
+
 static inline int virtio_net_hdr_set_proto(struct sk_buff *skb,
                                           const struct virtio_net_hdr *hdr)
 {
@@ -88,9 +103,12 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
                        if (!skb->protocol) {
                                __be16 protocol = dev_parse_header_protocol(skb);
 
-                               virtio_net_hdr_set_proto(skb, hdr);
-                               if (protocol && protocol != skb->protocol)
+                               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;
                        }
 retry:
                        if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,