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Message-ID: <2a2666256b330348437cde92a6bff24ae70e2b46.1763345426.git.xudu@redhat.com>
Date: Mon, 17 Nov 2025 14:25:02 +0800
From: xu du <xudu@...hat.com>
To: davem@...emloft.net,
edumazet@...gle.com,
kuba@...nel.org,
pabeni@...hat.com
Cc: netdev@...r.kernel.org
Subject: [PATCH net-next 6/8] selftest: tun: Add test for sending gso packet into tun
The test constructs a raw packet, prepends a virtio_net_hdr,
and writes the result to the TUN device. This mimics the behavior
of a vm forwarding a guest's packet to the host networking stack.
Signed-off-by: xu du <xudu@...hat.com>
---
tools/testing/selftests/net/tun.c | 149 ++++++++++++++++++++++++++++--
1 file changed, 140 insertions(+), 9 deletions(-)
diff --git a/tools/testing/selftests/net/tun.c b/tools/testing/selftests/net/tun.c
index 8f0188ccb9fb..870697a0d9e8 100644
--- a/tools/testing/selftests/net/tun.c
+++ b/tools/testing/selftests/net/tun.c
@@ -75,6 +75,31 @@ static struct in6_addr param_ipaddr6_inner_src = {
#define TUN_VNET_TNL_SIZE sizeof(struct virtio_net_hdr_v1_hash_tunnel)
+#define MAX_VNET_TUNNEL_PACKET_SZ (TUN_VNET_TNL_SIZE + ETH_HLEN + ETH_MAX_MTU)
+
+#define UDP_TUNNEL_VXLAN_4IN4_HDRLEN \
+ (ETH_HLEN + 2 * sizeof(struct iphdr) + 8 + 2 * sizeof(struct udphdr))
+#define UDP_TUNNEL_VXLAN_6IN6_HDRLEN \
+ (ETH_HLEN + 2 * sizeof(struct ipv6hdr) + 8 + 2 * sizeof(struct udphdr))
+#define UDP_TUNNEL_VXLAN_4IN6_HDRLEN \
+ (ETH_HLEN + sizeof(struct iphdr) + sizeof(struct ipv6hdr) + 8 + \
+ 2 * sizeof(struct udphdr))
+#define UDP_TUNNEL_VXLAN_6IN4_HDRLEN \
+ (ETH_HLEN + sizeof(struct ipv6hdr) + sizeof(struct iphdr) + 8 + \
+ 2 * sizeof(struct udphdr))
+
+#define UDP_TUNNEL_HDRLEN(type) \
+ ((type) == UDP_TUNNEL_VXLAN_4IN4 ? UDP_TUNNEL_VXLAN_4IN4_HDRLEN : \
+ (type) == UDP_TUNNEL_VXLAN_6IN4 ? UDP_TUNNEL_VXLAN_6IN4_HDRLEN : \
+ (type) == UDP_TUNNEL_VXLAN_4IN6 ? UDP_TUNNEL_VXLAN_4IN6_HDRLEN : \
+ (type) == UDP_TUNNEL_VXLAN_6IN6 ? UDP_TUNNEL_VXLAN_6IN6_HDRLEN : \
+ 0)
+
+#define UDP_TUNNEL_MSS(type) (ETH_DATA_LEN - UDP_TUNNEL_HDRLEN(type))
+
+#define UDP_TUNNEL_MAX(type, is_tap) \
+ (ETH_MAX_MTU - UDP_TUNNEL_HDRLEN(type) - ((is_tap) ? ETH_HLEN : 0))
+
union vxlan_addr {
struct sockaddr_in sin;
struct sockaddr_in6 sin6;
@@ -384,15 +409,23 @@ FIXTURE(tun_vnet_udptnl)
FIXTURE_VARIANT(tun_vnet_udptnl)
{
int tunnel_type;
- bool is_tap;
+ int gso_size;
+ int data_size;
+ int r_num_mss;
+ bool is_tap, no_gso;
};
/* clang-format off */
#define TUN_VNET_UDPTNL_VARIANT_ADD(type, desc) \
- FIXTURE_VARIANT_ADD(tun_vnet_udptnl, desc##udptnl) { \
+ FIXTURE_VARIANT_ADD(tun_vnet_udptnl, desc##_1mss) { \
+ /* send a single MSS: fall back to no GSO */ \
.tunnel_type = type, \
+ .gso_size = UDP_TUNNEL_MSS(type), \
+ .data_size = UDP_TUNNEL_MSS(type), \
+ .r_num_mss = 1, \
.is_tap = true, \
- }
+ .no_gso = true, \
+ };
/* clang-format on */
TUN_VNET_UDPTNL_VARIANT_ADD(UDP_TUNNEL_VXLAN_4IN4, 4in4);
@@ -510,14 +543,112 @@ FIXTURE_TEARDOWN(tun_vnet_udptnl)
EXPECT_EQ(ret, 0);
}
-TEST_F(tun_vnet_udptnl, basic)
+static int build_gso_packet_into_tun(const FIXTURE_VARIANT(tun_vnet_udptnl) *
+ variant,
+ uint8_t *buf)
{
- int ret;
- char cmd[256] = { 0 };
+ int tunnel_type = variant->tunnel_type;
+ int payload_len = variant->data_size;
+ int gso_size = variant->gso_size;
+ int inner_family, outer_family;
+ bool is_tap = variant->is_tap;
+ uint8_t *outer_udph = NULL;
+ uint8_t *cur = buf;
+ int len, proto;
+
+ len = (is_tap ? ETH_HLEN : 0) + UDP_TUNNEL_HDRLEN(tunnel_type);
+ inner_family = (tunnel_type & UDP_TUNNEL_INNER_IPV4) ? AF_INET :
+ AF_INET6;
+ outer_family = (tunnel_type & UDP_TUNNEL_OUTER_IPV4) ? AF_INET :
+ AF_INET6;
+
+ cur += build_virtio_net_hdr_v1_hash_tunnel(cur, is_tap, len, gso_size,
+ outer_family, inner_family);
+
+ if (is_tap) {
+ proto = outer_family == AF_INET ? ETH_P_IP : ETH_P_IPV6;
+ cur += build_eth(cur, proto, param_hwaddr_outer_dst,
+ param_hwaddr_outer_src);
+ len -= ETH_HLEN;
+ }
- sprintf(cmd, "ip addr show %s > /dev/null 2>&1", param_dev_vxlan_name);
- ret = system(cmd);
- ASSERT_EQ(ret, 0);
+ if (outer_family == AF_INET) {
+ len = len - sizeof(struct iphdr) + payload_len;
+ cur += build_ipv4_header(cur, IPPROTO_UDP, len,
+ ¶m_ipaddr4_outer_dst,
+ ¶m_ipaddr4_outer_src);
+ } else {
+ len = len - sizeof(struct ipv6hdr) + payload_len;
+ cur += build_ipv6_header(cur, IPPROTO_UDP, 0, len,
+ ¶m_ipaddr6_outer_dst,
+ ¶m_ipaddr6_outer_src);
+ }
+
+ outer_udph = cur;
+ len -= sizeof(struct udphdr);
+ proto = inner_family == AF_INET ? ETH_P_IP : ETH_P_IPV6;
+ cur += build_udp_header(cur, UDP_SRC_PORT, VN_PORT, len);
+ cur += build_vxlan_header(cur, VN_ID);
+ cur += build_eth(cur, proto, param_hwaddr_inner_dst,
+ param_hwaddr_inner_src);
+
+ len = sizeof(struct udphdr) + payload_len;
+ if (inner_family == AF_INET) {
+ cur += build_ipv4_header(cur, IPPROTO_UDP, len,
+ ¶m_ipaddr4_inner_dst,
+ ¶m_ipaddr4_inner_src);
+ } else {
+ cur += build_ipv6_header(cur, IPPROTO_UDP, 0, len,
+ ¶m_ipaddr6_inner_dst,
+ ¶m_ipaddr6_inner_src);
+ }
+
+ cur += build_udp_packet(cur, UDP_DST_PORT, UDP_SRC_PORT, payload_len,
+ inner_family, false);
+
+ build_udp_packet_csum(outer_udph, outer_family, false);
+
+ return cur - buf;
+}
+
+static int
+recieve_gso_packet_from_tunnel(FIXTURE_DATA(tun_vnet_udptnl) * self,
+ const FIXTURE_VARIANT(tun_vnet_udptnl) * variant,
+ int *r_num_mss)
+{
+ uint8_t packet_buf[MAX_VNET_TUNNEL_PACKET_SZ];
+ int len, total_len = 0, socket = self->sock;
+ int payload_len = variant->data_size;
+
+ while (total_len < payload_len) {
+ len = recv(socket, packet_buf, sizeof(packet_buf), 0);
+ if (len < 0) {
+ if (errno != EAGAIN && errno != EWOULDBLOCK)
+ perror("recv");
+ return total_len;
+ }
+
+ (*r_num_mss)++;
+ total_len += len;
+ }
+
+ return total_len;
+}
+
+TEST_F(tun_vnet_udptnl, send_gso_packet)
+{
+ uint8_t pkt[MAX_VNET_TUNNEL_PACKET_SZ];
+ int r_num_mss = 0;
+ int ret, off;
+
+ memset(pkt, 0, sizeof(pkt));
+ off = build_gso_packet_into_tun(variant, pkt);
+ ret = write(self->fd, pkt, off);
+ ASSERT_EQ(ret, off);
+
+ ret = recieve_gso_packet_from_tunnel(self, variant, &r_num_mss);
+ ASSERT_EQ(ret, variant->data_size);
+ ASSERT_EQ(r_num_mss, variant->r_num_mss);
}
TEST_HARNESS_MAIN
--
2.49.0
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