selftests/bpf: add ipv4 and dual ipv4/ipv6 support in btf_skc_cls_ingress

btf_skc_cls_ingress test currently checks that syncookie and
bpf_sk_assign/release helpers behave correctly in multiple scenarios,
but only with ipv6 socket.

Increase those helpers coverage by adding testing support for IPv4
sockets and IPv4/IPv6 sockets. The rework is mostly based on features
brought earlier in test_tcp_check_syncookie.sh to cover some fixes
performed on those helpers, but test_tcp_check_syncookie.sh is not
integrated in test_progs. The most notable changes linked to this are:
- some rework in the corresponding eBPF program to support both types of
traffic
- the switch from start_server to start_server_str to allow to check
some socket options
- the introduction of new subtests for ipv4 and ipv4/ipv6

Signed-off-by: Alexis Lothoré (eBPF Foundation) <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Martin KaFai Lau <[e-mail]>

tools/testing/selftests/bpf/prog_tests/btf_skc_cls_ingress.c

···
 
 #define TEST_NS "skc_cls_ingress"
 
+#define BIT(n)		(1 << (n))
+#define TEST_MODE_IPV4	BIT(0)
+#define TEST_MODE_IPV6	BIT(1)
+#define TEST_MODE_DUAL	(TEST_MODE_IPV4 | TEST_MODE_IPV6)
+
+#define SERVER_ADDR_IPV4	"127.0.0.1"
+#define SERVER_ADDR_IPV6	"::1"
+#define SERVER_ADDR_DUAL	"::0"
+
 static struct netns_obj *prepare_netns(struct test_btf_skc_cls_ingress *skel)
 {
 	LIBBPF_OPTS(bpf_tc_hook, qdisc_lo, .attach_point = BPF_TC_INGRESS);
···
 
 static void reset_test(struct test_btf_skc_cls_ingress *skel)
 {
+	memset(&skel->bss->srv_sa4, 0, sizeof(skel->bss->srv_sa4));
 	memset(&skel->bss->srv_sa6, 0, sizeof(skel->bss->srv_sa6));
 	skel->bss->listen_tp_sport = 0;
 	skel->bss->req_sk_sport = 0;
···
 		printf("bpf prog error at line %u\n", skel->bss->linum);
 }
 
-static void run_test(struct test_btf_skc_cls_ingress *skel, bool gen_cookies)
+static int v6only_true(int fd, void *opts)
+{
+	int mode = true;
+
+	return setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &mode, sizeof(mode));
+}
+
+static int v6only_false(int fd, void *opts)
+{
+	int mode = false;
+
+	return setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &mode, sizeof(mode));
+}
+
+static void run_test(struct test_btf_skc_cls_ingress *skel, bool gen_cookies,
+		     int ip_mode)
 {
 	const char *tcp_syncookies = gen_cookies ? "2" : "1";
 	int listen_fd = -1, cli_fd = -1, srv_fd = -1, err;
+	struct network_helper_opts opts = { 0 };
+	struct sockaddr_storage *addr;
 	struct sockaddr_in6 srv_sa6;
-	socklen_t addrlen = sizeof(srv_sa6);
+	struct sockaddr_in srv_sa4;
+	socklen_t addr_len;
+	int sock_family;
+	char *srv_addr;
 	int srv_port;
+
+	switch (ip_mode) {
+	case TEST_MODE_IPV4:
+		sock_family = AF_INET;
+		srv_addr = SERVER_ADDR_IPV4;
+		addr = (struct sockaddr_storage *)&srv_sa4;
+		addr_len = sizeof(srv_sa4);
+		break;
+	case TEST_MODE_IPV6:
+		opts.post_socket_cb = v6only_true;
+		sock_family = AF_INET6;
+		srv_addr = SERVER_ADDR_IPV6;
+		addr = (struct sockaddr_storage *)&srv_sa6;
+		addr_len = sizeof(srv_sa6);
+		break;
+	case TEST_MODE_DUAL:
+		opts.post_socket_cb = v6only_false;
+		sock_family = AF_INET6;
+		srv_addr = SERVER_ADDR_DUAL;
+		addr = (struct sockaddr_storage *)&srv_sa6;
+		addr_len = sizeof(srv_sa6);
+		break;
+	default:
+		PRINT_FAIL("Unknown IP mode %d", ip_mode);
+		return;
+	}
 
 	if (write_sysctl("/proc/sys/net/ipv4/tcp_syncookies", tcp_syncookies))
 		return;
 
-	listen_fd = start_server(AF_INET6, SOCK_STREAM, "::1", 0, 0);
+	listen_fd = start_server_str(sock_family, SOCK_STREAM, srv_addr,  0,
+				     &opts);
 	if (!ASSERT_OK_FD(listen_fd, "start server"))
 		return;
 
-	err = getsockname(listen_fd, (struct sockaddr *)&srv_sa6, &addrlen);
+	err = getsockname(listen_fd, (struct sockaddr *)addr, &addr_len);
 	if (!ASSERT_OK(err, "getsockname(listen_fd)"))
 		goto done;
-	memcpy(&skel->bss->srv_sa6, &srv_sa6, sizeof(srv_sa6));
-	srv_port = ntohs(srv_sa6.sin6_port);
+
+	switch (ip_mode) {
+	case TEST_MODE_IPV4:
+		memcpy(&skel->bss->srv_sa4, &srv_sa4, sizeof(srv_sa4));
+		srv_port = ntohs(srv_sa4.sin_port);
+		break;
+	case TEST_MODE_IPV6:
+	case TEST_MODE_DUAL:
+		memcpy(&skel->bss->srv_sa6, &srv_sa6, sizeof(srv_sa6));
+		srv_port = ntohs(srv_sa6.sin6_port);
+		break;
+	default:
+		goto done;
+	}
 
 	cli_fd = connect_to_fd(listen_fd, 0);
 	if (!ASSERT_OK_FD(cli_fd, "connect client"))
···
 		close(srv_fd);
 }
 
-static void test_conn(struct test_btf_skc_cls_ingress *skel)
+static void test_conn_ipv4(struct test_btf_skc_cls_ingress *skel)
 {
-	run_test(skel, false);
+	run_test(skel, false, TEST_MODE_IPV4);
 }
 
-static void test_syncookie(struct test_btf_skc_cls_ingress *skel)
+static void test_conn_ipv6(struct test_btf_skc_cls_ingress *skel)
 {
-	run_test(skel, true);
+	run_test(skel, false, TEST_MODE_IPV6);
+}
+
+static void test_conn_dual(struct test_btf_skc_cls_ingress *skel)
+{
+	run_test(skel, false, TEST_MODE_DUAL);
+}
+
+static void test_syncookie_ipv4(struct test_btf_skc_cls_ingress *skel)
+{
+	run_test(skel, true, TEST_MODE_IPV4);
+}
+
+static void test_syncookie_ipv6(struct test_btf_skc_cls_ingress *skel)
+{
+	run_test(skel, true, TEST_MODE_IPV6);
+}
+
+static void test_syncookie_dual(struct test_btf_skc_cls_ingress *skel)
+{
+	run_test(skel, true, TEST_MODE_DUAL);
 }
 
 struct test {
···
 
 #define DEF_TEST(name) { #name, test_##name }
 static struct test tests[] = {
-	DEF_TEST(conn),
-	DEF_TEST(syncookie),
+	DEF_TEST(conn_ipv4),
+	DEF_TEST(conn_ipv6),
+	DEF_TEST(conn_dual),
+	DEF_TEST(syncookie_ipv4),
+	DEF_TEST(syncookie_ipv6),
+	DEF_TEST(syncookie_dual),
 };
 
 void test_btf_skc_cls_ingress(void)

tools/testing/selftests/bpf/progs/test_btf_skc_cls_ingress.c

···
 #endif
 
 struct sockaddr_in6 srv_sa6 = {};
+struct sockaddr_in srv_sa4 = {};
 __u16 listen_tp_sport = 0;
 __u16 req_sk_sport = 0;
 __u32 recv_cookie = 0;
···
 
 #define LOG() ({ if (!linum) linum = __LINE__; })
 
-static void test_syncookie_helper(struct ipv6hdr *ip6h, struct tcphdr *th,
-				  struct tcp_sock *tp,
+static void test_syncookie_helper(void *iphdr, int iphdr_size,
+				  struct tcphdr *th, struct tcp_sock *tp,
 				  struct __sk_buff *skb)
 {
 	if (th->syn) {
···
 			return;
 		}
 
-		mss_cookie = bpf_tcp_gen_syncookie(tp, ip6h, sizeof(*ip6h),
+		mss_cookie = bpf_tcp_gen_syncookie(tp, iphdr, iphdr_size,
 						   th, 40);
 		if (mss_cookie < 0) {
 			if (mss_cookie != -ENOENT)
···
 		}
 	} else if (gen_cookie) {
 		/* It was in cookie mode */
-		int ret = bpf_tcp_check_syncookie(tp, ip6h, sizeof(*ip6h),
+		int ret = bpf_tcp_check_syncookie(tp, iphdr, iphdr_size,
 						  th, sizeof(*th));
 
 		if (ret < 0) {
···
 	}
 }
 
-static int handle_ip6_tcp(struct ipv6hdr *ip6h, struct __sk_buff *skb)
+static int handle_ip_tcp(struct ethhdr *eth, struct __sk_buff *skb)
 {
-	struct bpf_sock_tuple *tuple;
+	struct bpf_sock_tuple *tuple = NULL;
+	unsigned int tuple_len = 0;
 	struct bpf_sock *bpf_skc;
-	unsigned int tuple_len;
+	void *data_end, *iphdr;
+	struct ipv6hdr *ip6h;
+	struct iphdr *ip4h;
 	struct tcphdr *th;
-	void *data_end;
+	int iphdr_size;
 
 	data_end = (void *)(long)(skb->data_end);
 
-	th = (struct tcphdr *)(ip6h + 1);
-	if (th + 1 > data_end)
+	switch (eth->h_proto) {
+	case bpf_htons(ETH_P_IP):
+		ip4h = (struct iphdr *)(eth + 1);
+		if (ip4h + 1 > data_end)
+			return TC_ACT_OK;
+		if (ip4h->protocol != IPPROTO_TCP)
+			return TC_ACT_OK;
+		th = (struct tcphdr *)(ip4h + 1);
+		if (th + 1 > data_end)
+			return TC_ACT_OK;
+		/* Is it the testing traffic? */
+		if (th->dest != srv_sa4.sin_port)
+			return TC_ACT_OK;
+		tuple_len = sizeof(tuple->ipv4);
+		tuple = (struct bpf_sock_tuple *)&ip4h->saddr;
+		iphdr = ip4h;
+		iphdr_size = sizeof(*ip4h);
+		break;
+	case bpf_htons(ETH_P_IPV6):
+		ip6h = (struct ipv6hdr *)(eth + 1);
+		if (ip6h + 1 > data_end)
+			return TC_ACT_OK;
+		if (ip6h->nexthdr != IPPROTO_TCP)
+			return TC_ACT_OK;
+		th = (struct tcphdr *)(ip6h + 1);
+		if (th + 1 > data_end)
+			return TC_ACT_OK;
+		/* Is it the testing traffic? */
+		if (th->dest != srv_sa6.sin6_port)
+			return TC_ACT_OK;
+		tuple_len = sizeof(tuple->ipv6);
+		tuple = (struct bpf_sock_tuple *)&ip6h->saddr;
+		iphdr = ip6h;
+		iphdr_size = sizeof(*ip6h);
+		break;
+	default:
 		return TC_ACT_OK;
+	}
 
-	/* Is it the testing traffic? */
-	if (th->dest != srv_sa6.sin6_port)
-		return TC_ACT_OK;
-
-	tuple_len = sizeof(tuple->ipv6);
-	tuple = (struct bpf_sock_tuple *)&ip6h->saddr;
 	if ((void *)tuple + tuple_len > data_end) {
 		LOG();
 		return TC_ACT_OK;
···
 
 		listen_tp_sport = tp->inet_conn.icsk_inet.sk.__sk_common.skc_num;
 
-		test_syncookie_helper(ip6h, th, tp, skb);
+		test_syncookie_helper(iphdr, iphdr_size, th, tp, skb);
 		bpf_sk_release(tp);
 		return TC_ACT_OK;
 	}
···
 SEC("tc")
 int cls_ingress(struct __sk_buff *skb)
 {
-	struct ipv6hdr *ip6h;
 	struct ethhdr *eth;
 	void *data_end;
 
···
 	if (eth + 1 > data_end)
 		return TC_ACT_OK;
 
-	if (eth->h_proto != bpf_htons(ETH_P_IPV6))
+	if (eth->h_proto != bpf_htons(ETH_P_IP) &&
+	    eth->h_proto != bpf_htons(ETH_P_IPV6))
 		return TC_ACT_OK;
 
-	ip6h = (struct ipv6hdr *)(eth + 1);
-	if (ip6h + 1 > data_end)
-		return TC_ACT_OK;
-
-	if (ip6h->nexthdr == IPPROTO_TCP)
-		return handle_ip6_tcp(ip6h, skb);
-
-	return TC_ACT_OK;
+	return handle_ip_tcp(eth, skb);
 }
 
 char _license[] SEC("license") = "GPL";