[PATCH net 3/3] selftests: net: tun: test outer protocol of UDP tunnel GSO packets

[Eric Dumazet <edumazet@kernel.org>]

Add a tun_vnet_udptnl_proto fixture writing single 4in4 Geneve GSO
frames to a tap device with UDP tunnel offloads enabled:

- outer_proto_ok: an outer IPv4 header, with or without an 802.1Q tag,
  is accepted.
- outer_proto_bad: an outer ethertype that does not match the declared
  tunnel type (IPv6 on an IPv4 tunnel, or NSH, with or without a VLAN
  tag) is rejected with EINVAL.

Without the previous virtio_net patch, outer_proto_bad fails because
the kernel accepts the frames.

Signed-off-by: Eric Dumazet <edumazet@kernel.org>
---
 tools/testing/selftests/net/tun.c | 130 ++++++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)

diff --git a/tools/testing/selftests/net/tun.c b/tools/testing/selftests/net/tun.c
index 34de2580e32e..47a24b9c477b 100644
--- a/tools/testing/selftests/net/tun.c
+++ b/tools/testing/selftests/net/tun.c
@@ -683,6 +683,136 @@ TEST_F(tun_vnet_gso, vlan_tcpv4_gso_no_csum_64k)
 	ASSERT_EQ(ret, len);
 }
 
+#ifndef ETH_P_NSH
+#define ETH_P_NSH 0x894F
+#endif
+
+FIXTURE(tun_vnet_udptnl_proto)
+{
+	char ifname[IFNAMSIZ];
+	uint8_t *pkt;
+	int fd;
+};
+
+FIXTURE_SETUP(tun_vnet_udptnl_proto)
+{
+	int flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
+	int features = TUN_F_CSUM | TUN_F_UDP_TUNNEL_GSO |
+		       TUN_F_UDP_TUNNEL_GSO_CSUM | TUN_F_USO4 | TUN_F_USO6;
+
+	self->fd = -1;
+	if (unshare(CLONE_NEWNET))
+		SKIP(return, "Cannot create network namespace: %s",
+		     strerror(errno));
+
+	self->pkt = calloc(1, MAX_VNET_TUNNEL_PACKET_SZ);
+	ASSERT_NE(self->pkt, NULL);
+
+	memset(self->ifname, 0, sizeof(self->ifname));
+	self->fd = tun_open(self->ifname, flags, TUN_VNET_TNL_SIZE, features,
+			    param_hwaddr_outer_src);
+	ASSERT_GE(self->fd, 0);
+}
+
+FIXTURE_TEARDOWN(tun_vnet_udptnl_proto)
+{
+	if (self->fd >= 0)
+		close(self->fd);
+	free(self->pkt);
+}
+
+/* Build a 4in4 Geneve GSO frame whose outer ethertype is @l3proto,
+ * optionally behind an 802.1Q tag.
+ */
+static int build_udptnl_frame(uint8_t *buf, bool vlan, uint16_t l3proto,
+			      int payload_len)
+{
+	struct virtio_net_hdr_v1_hash_tunnel *vh = (void *)buf;
+	int vlan_len = vlan ? 4 : 0;
+	int hlen = ETH_HLEN + vlan_len + UDP_TUNNEL_GENEVE_4IN4_HDRLEN;
+	uint8_t *outer_udph, *cur = buf;
+	int pktlen;
+
+	cur += build_virtio_net_hdr_v1_hash_tunnel(cur, true, hlen, 1400,
+						   AF_INET, AF_INET);
+	vh->outer_th_offset += vlan_len;
+	vh->inner_nh_offset += vlan_len;
+	vh->hash_hdr.hdr.csum_start += vlan_len;
+
+	if (vlan) {
+		uint16_t vlan_tag[2] = { htons(100), htons(l3proto) };
+
+		cur += build_eth(cur, ETH_P_8021Q, param_hwaddr_outer_dst,
+				 param_hwaddr_outer_src);
+		memcpy(cur, vlan_tag, sizeof(vlan_tag));
+		cur += sizeof(vlan_tag);
+	} else {
+		cur += build_eth(cur, l3proto, param_hwaddr_outer_dst,
+				 param_hwaddr_outer_src);
+	}
+
+	pktlen = UDP_TUNNEL_GENEVE_4IN4_HDRLEN - sizeof(struct iphdr) +
+		 payload_len;
+	cur += build_ipv4_header(cur, IPPROTO_UDP, pktlen,
+				 &param_ipaddr4_outer_dst,
+				 &param_ipaddr4_outer_src);
+
+	outer_udph = cur;
+	cur += build_udp_header(cur, UDP_SRC_PORT, VN_PORT,
+				pktlen - sizeof(struct udphdr));
+	cur += build_geneve_header(cur, VN_ID);
+	cur += build_eth(cur, ETH_P_IP, param_hwaddr_inner_dst,
+			 param_hwaddr_inner_src);
+	cur += build_ipv4_header(cur, IPPROTO_UDP,
+				 sizeof(struct udphdr) + payload_len,
+				 &param_ipaddr4_inner_dst,
+				 &param_ipaddr4_inner_src);
+	cur += build_udp_packet(cur, UDP_DST_PORT, UDP_SRC_PORT, payload_len,
+				AF_INET, false);
+	build_udp_packet_csum(outer_udph, AF_INET, false);
+
+	return cur - buf;
+}
+
+TEST_F(tun_vnet_udptnl_proto, outer_proto_ok)
+{
+	uint8_t *pkt = self->pkt;
+	int len, ret;
+
+	len = build_udptnl_frame(pkt, false, ETH_P_IP, 2800);
+	ret = write(self->fd, pkt, len);
+	ASSERT_EQ(ret, len);
+
+	/* The outer IPv4 header can follow a VLAN tag. */
+	len = build_udptnl_frame(pkt, true, ETH_P_IP, 2800);
+	ret = write(self->fd, pkt, len);
+	ASSERT_EQ(ret, len);
+}
+
+TEST_F(tun_vnet_udptnl_proto, outer_proto_bad)
+{
+	uint8_t *pkt = self->pkt;
+	int len, ret;
+
+	/* Outer ethertype does not match the declared IPv4 tunnel. */
+	len = build_udptnl_frame(pkt, false, ETH_P_IPV6, 2800);
+	ret = write(self->fd, pkt, len);
+	ASSERT_EQ(ret, -1);
+	ASSERT_EQ(errno, EINVAL);
+
+	/* Outer header is not IP at all. */
+	len = build_udptnl_frame(pkt, false, ETH_P_NSH, 2800);
+	ret = write(self->fd, pkt, len);
+	ASSERT_EQ(ret, -1);
+	ASSERT_EQ(errno, EINVAL);
+
+	/* Same, behind a VLAN tag. */
+	len = build_udptnl_frame(pkt, true, ETH_P_NSH, 2800);
+	ret = write(self->fd, pkt, len);
+	ASSERT_EQ(ret, -1);
+	ASSERT_EQ(errno, EINVAL);
+}
+
 FIXTURE(tun_vnet_udptnl)
 {
 	char ifname[IFNAMSIZ];
-- 
2.53.0