Message-Id: <20251022-tc_tunnel-v2-1-a44a0bd52902@bootlin.com>
Date: Wed, 22 Oct 2025 09:39:50 +0200
From: Alexis Lothoré (eBPF Foundation) <alexis.lothore@...tlin.com>
To: Alexei Starovoitov <ast@...nel.org>, 
 Daniel Borkmann <daniel@...earbox.net>, Andrii Nakryiko <andrii@...nel.org>, 
 Martin KaFai Lau <martin.lau@...ux.dev>, 
 Eduard Zingerman <eddyz87@...il.com>, Song Liu <song@...nel.org>, 
 Yonghong Song <yonghong.song@...ux.dev>, 
 John Fastabend <john.fastabend@...il.com>, KP Singh <kpsingh@...nel.org>, 
 Stanislav Fomichev <sdf@...ichev.me>, Hao Luo <haoluo@...gle.com>, 
 Jiri Olsa <jolsa@...nel.org>, Shuah Khan <shuah@...nel.org>
Cc: ebpf@...uxfoundation.org, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 Bastien Curutchet <bastien.curutchet@...tlin.com>, bpf@...r.kernel.org, 
 linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org, 
 Alexis Lothoré (eBPF Foundation) <alexis.lothore@...tlin.com>
Subject: [PATCH bpf-next v2 1/4] selftests/bpf: add tc helpers

The test_tunnel.c file defines small fonctions to easily attach eBPF
programs to tc hooks, either on egress, ingress or both.

Create a shared helper in network_helpers.c so that other tests can
benefit from it.

Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@...tlin.com>
---
Changes in v2:
- declare new TC API in network_helpers instead of a dedicated file
- only declare tc_prog_attach, not the intermediate
  "generic_attachigr_fd/egr_fd
- pass an interface name rather than an interface id
- update accordingly test_tunnel.c
---
 tools/testing/selftests/bpf/network_helpers.c      |  45 +++++++++
 tools/testing/selftests/bpf/network_helpers.h      |  16 +++
 .../testing/selftests/bpf/prog_tests/test_tunnel.c | 107 +++------------------
 3 files changed, 75 insertions(+), 93 deletions(-)

diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c
index cdf7b6641444..0998d71fe57a 100644
--- a/tools/testing/selftests/bpf/network_helpers.c
+++ b/tools/testing/selftests/bpf/network_helpers.c
@@ -766,6 +766,51 @@ int send_recv_data(int lfd, int fd, uint32_t total_bytes)
 	return err;
 }
 
+int tc_prog_attach(const char *dev, int ingress_fd, int egress_fd)
+{
+	int ifindex;
+
+	if (!ASSERT_TRUE(ingress_fd >= 0 || egress_fd >= 0,
+			 "at least one program fd is valid"))
+		return -1;
+
+	ifindex = if_nametoindex(dev);
+	if (!ASSERT_NEQ(ifindex, 0, "get ifindex"))
+		return -1;
+
+	DECLARE_LIBBPF_OPTS(bpf_tc_hook, hook, .ifindex = ifindex,
+			    .attach_point = BPF_TC_INGRESS | BPF_TC_EGRESS);
+	DECLARE_LIBBPF_OPTS(bpf_tc_opts, opts1, .handle = 1,
+			    .priority = 1, .prog_fd = ingress_fd);
+	DECLARE_LIBBPF_OPTS(bpf_tc_opts, opts2, .handle = 1,
+			    .priority = 1, .prog_fd = egress_fd);
+	int ret;
+
+	ret = bpf_tc_hook_create(&hook);
+	if (!ASSERT_OK(ret, "create tc hook"))
+		return ret;
+
+	if (ingress_fd >= 0) {
+		hook.attach_point = BPF_TC_INGRESS;
+		ret = bpf_tc_attach(&hook, &opts1);
+		if (!ASSERT_OK(ret, "bpf_tc_attach")) {
+			bpf_tc_hook_destroy(&hook);
+			return ret;
+		}
+	}
+
+	if (egress_fd >= 0) {
+		hook.attach_point = BPF_TC_EGRESS;
+		ret = bpf_tc_attach(&hook, &opts2);
+		if (!ASSERT_OK(ret, "bpf_tc_attach")) {
+			bpf_tc_hook_destroy(&hook);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
 #ifdef TRAFFIC_MONITOR
 struct tmonitor_ctx {
 	pcap_t *pcap;
diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h
index ef208eefd571..79a010c88e11 100644
--- a/tools/testing/selftests/bpf/network_helpers.h
+++ b/tools/testing/selftests/bpf/network_helpers.h
@@ -255,6 +255,22 @@ struct tmonitor_ctx;
 
 typedef int (*tm_print_fn_t)(const char *format, va_list args);
 
+/**
+ * tc_prog_attach - attach BPF program(s) to an interface
+ *
+ * Takes file descriptors pointing to at least one, at most two BPF
+ * programs, and attach those programs to an interface ingress, egress or
+ * both.
+ *
+ * @dev: string containing the interface name
+ * @ingress_fd: file descriptor of the program to attach to interface ingress
+ * @egress_fd: file descriptor of the program to attach to interface egress
+ *
+ * Returns 0 on success, -1 if no valid file descriptor has been found, if
+ * the interface name is invalid or if an error ocurred during attach.
+ */
+int tc_prog_attach(const char *dev, int ingress_fd, int egress_fd);
+
 #ifdef TRAFFIC_MONITOR
 struct tmonitor_ctx *traffic_monitor_start(const char *netns, const char *test_name,
 					   const char *subtest_name);
diff --git a/tools/testing/selftests/bpf/prog_tests/test_tunnel.c b/tools/testing/selftests/bpf/prog_tests/test_tunnel.c
index bae0e9de277d..eb9309931272 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_tunnel.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_tunnel.c
@@ -534,85 +534,6 @@ static void ping6_dev1(void)
 	close_netns(nstoken);
 }
 
-static int attach_tc_prog(int ifindex, int igr_fd, int egr_fd)
-{
-	DECLARE_LIBBPF_OPTS(bpf_tc_hook, hook, .ifindex = ifindex,
-			    .attach_point = BPF_TC_INGRESS | BPF_TC_EGRESS);
-	DECLARE_LIBBPF_OPTS(bpf_tc_opts, opts1, .handle = 1,
-			    .priority = 1, .prog_fd = igr_fd);
-	DECLARE_LIBBPF_OPTS(bpf_tc_opts, opts2, .handle = 1,
-			    .priority = 1, .prog_fd = egr_fd);
-	int ret;
-
-	ret = bpf_tc_hook_create(&hook);
-	if (!ASSERT_OK(ret, "create tc hook"))
-		return ret;
-
-	if (igr_fd >= 0) {
-		hook.attach_point = BPF_TC_INGRESS;
-		ret = bpf_tc_attach(&hook, &opts1);
-		if (!ASSERT_OK(ret, "bpf_tc_attach")) {
-			bpf_tc_hook_destroy(&hook);
-			return ret;
-		}
-	}
-
-	if (egr_fd >= 0) {
-		hook.attach_point = BPF_TC_EGRESS;
-		ret = bpf_tc_attach(&hook, &opts2);
-		if (!ASSERT_OK(ret, "bpf_tc_attach")) {
-			bpf_tc_hook_destroy(&hook);
-			return ret;
-		}
-	}
-
-	return 0;
-}
-
-static int generic_attach(const char *dev, int igr_fd, int egr_fd)
-{
-	int ifindex;
-
-	if (!ASSERT_OK_FD(igr_fd, "check ingress fd"))
-		return -1;
-	if (!ASSERT_OK_FD(egr_fd, "check egress fd"))
-		return -1;
-
-	ifindex = if_nametoindex(dev);
-	if (!ASSERT_NEQ(ifindex, 0, "get ifindex"))
-		return -1;
-
-	return attach_tc_prog(ifindex, igr_fd, egr_fd);
-}
-
-static int generic_attach_igr(const char *dev, int igr_fd)
-{
-	int ifindex;
-
-	if (!ASSERT_OK_FD(igr_fd, "check ingress fd"))
-		return -1;
-
-	ifindex = if_nametoindex(dev);
-	if (!ASSERT_NEQ(ifindex, 0, "get ifindex"))
-		return -1;
-
-	return attach_tc_prog(ifindex, igr_fd, -1);
-}
-
-static int generic_attach_egr(const char *dev, int egr_fd)
-{
-	int ifindex;
-
-	if (!ASSERT_OK_FD(egr_fd, "check egress fd"))
-		return -1;
-
-	ifindex = if_nametoindex(dev);
-	if (!ASSERT_NEQ(ifindex, 0, "get ifindex"))
-		return -1;
-
-	return attach_tc_prog(ifindex, -1, egr_fd);
-}
-
 static void test_vxlan_tunnel(void)
 {
 	struct test_tunnel_kern *skel = NULL;
@@ -635,12 +556,12 @@ static void test_vxlan_tunnel(void)
 		goto done;
 	get_src_prog_fd = bpf_program__fd(skel->progs.vxlan_get_tunnel_src);
 	set_src_prog_fd = bpf_program__fd(skel->progs.vxlan_set_tunnel_src);
-	if (generic_attach(VXLAN_TUNL_DEV1, get_src_prog_fd, set_src_prog_fd))
+	if (tc_prog_attach(VXLAN_TUNL_DEV1, get_src_prog_fd, set_src_prog_fd))
 		goto done;
 
 	/* load and attach bpf prog to veth dev tc hook point */
 	set_dst_prog_fd = bpf_program__fd(skel->progs.veth_set_outer_dst);
-	if (generic_attach_igr("veth1", set_dst_prog_fd))
+	if (tc_prog_attach("veth1", set_dst_prog_fd, -1))
 		goto done;
 
 	/* load and attach prog set_md to tunnel dev tc hook point at_ns0 */
@@ -648,7 +569,7 @@ static void test_vxlan_tunnel(void)
 	if (!ASSERT_OK_PTR(nstoken, "setns src"))
 		goto done;
 	set_dst_prog_fd = bpf_program__fd(skel->progs.vxlan_set_tunnel_dst);
-	if (generic_attach_egr(VXLAN_TUNL_DEV0, set_dst_prog_fd))
+	if (tc_prog_attach(VXLAN_TUNL_DEV0, -1, set_dst_prog_fd))
 		goto done;
 	close_netns(nstoken);
 
@@ -695,7 +616,7 @@ static void test_ip6vxlan_tunnel(void)
 		goto done;
 	get_src_prog_fd = bpf_program__fd(skel->progs.ip6vxlan_get_tunnel_src);
 	set_src_prog_fd = bpf_program__fd(skel->progs.ip6vxlan_set_tunnel_src);
-	if (generic_attach(IP6VXLAN_TUNL_DEV1, get_src_prog_fd, set_src_prog_fd))
+	if (tc_prog_attach(IP6VXLAN_TUNL_DEV1, get_src_prog_fd, set_src_prog_fd))
 		goto done;
 
 	/* load and attach prog set_md to tunnel dev tc hook point at_ns0 */
@@ -703,7 +624,7 @@ static void test_ip6vxlan_tunnel(void)
 	if (!ASSERT_OK_PTR(nstoken, "setns src"))
 		goto done;
 	set_dst_prog_fd = bpf_program__fd(skel->progs.ip6vxlan_set_tunnel_dst);
-	if (generic_attach_egr(IP6VXLAN_TUNL_DEV0, set_dst_prog_fd))
+	if (tc_prog_attach(IP6VXLAN_TUNL_DEV0, -1, set_dst_prog_fd))
 		goto done;
 	close_netns(nstoken);
 
@@ -764,7 +685,7 @@ static void test_ipip_tunnel(enum ipip_encap encap)
 			skel->progs.ipip_set_tunnel);
 	}
 
-	if (generic_attach(IPIP_TUNL_DEV1, get_src_prog_fd, set_src_prog_fd))
+	if (tc_prog_attach(IPIP_TUNL_DEV1, get_src_prog_fd, set_src_prog_fd))
 		goto done;
 
 	ping_dev0();
@@ -797,7 +718,7 @@ static void test_xfrm_tunnel(void)
 
 	/* attach tc prog to tunnel dev */
 	tc_prog_fd = bpf_program__fd(skel->progs.xfrm_get_state);
-	if (generic_attach_igr("veth1", tc_prog_fd))
+	if (tc_prog_attach("veth1", tc_prog_fd, -1))
 		goto done;
 
 	/* attach xdp prog to tunnel dev */
@@ -870,7 +791,7 @@ static void test_gre_tunnel(enum gre_test test)
 	if (!ASSERT_OK(err, "add tunnel"))
 		goto done;
 
-	if (generic_attach(GRE_TUNL_DEV1, get_fd, set_fd))
+	if (tc_prog_attach(GRE_TUNL_DEV1, get_fd, set_fd))
 		goto done;
 
 	ping_dev0();
@@ -911,7 +832,7 @@ static void test_ip6gre_tunnel(enum ip6gre_test test)
 
 	set_fd = bpf_program__fd(skel->progs.ip6gretap_set_tunnel);
 	get_fd = bpf_program__fd(skel->progs.ip6gretap_get_tunnel);
-	if (generic_attach(IP6GRE_TUNL_DEV1, get_fd, set_fd))
+	if (tc_prog_attach(IP6GRE_TUNL_DEV1, get_fd, set_fd))
 		goto done;
 
 	ping6_veth0();
@@ -954,7 +875,7 @@ static void test_erspan_tunnel(enum erspan_test test)
 
 	set_fd = bpf_program__fd(skel->progs.erspan_set_tunnel);
 	get_fd = bpf_program__fd(skel->progs.erspan_get_tunnel);
-	if (generic_attach(ERSPAN_TUNL_DEV1, get_fd, set_fd))
+	if (tc_prog_attach(ERSPAN_TUNL_DEV1, get_fd, set_fd))
 		goto done;
 
 	ping_dev0();
@@ -990,7 +911,7 @@ static void test_ip6erspan_tunnel(enum erspan_test test)
 
 	set_fd = bpf_program__fd(skel->progs.ip4ip6erspan_set_tunnel);
 	get_fd = bpf_program__fd(skel->progs.ip4ip6erspan_get_tunnel);
-	if (generic_attach(IP6ERSPAN_TUNL_DEV1, get_fd, set_fd))
+	if (tc_prog_attach(IP6ERSPAN_TUNL_DEV1, get_fd, set_fd))
 		goto done;
 
 	ping6_veth0();
@@ -1017,7 +938,7 @@ static void test_geneve_tunnel(void)
 
 	set_fd = bpf_program__fd(skel->progs.geneve_set_tunnel);
 	get_fd = bpf_program__fd(skel->progs.geneve_get_tunnel);
-	if (generic_attach(GENEVE_TUNL_DEV1, get_fd, set_fd))
+	if (tc_prog_attach(GENEVE_TUNL_DEV1, get_fd, set_fd))
 		goto done;
 
 	ping_dev0();
@@ -1044,7 +965,7 @@ static void test_ip6geneve_tunnel(void)
 
 	set_fd = bpf_program__fd(skel->progs.ip6geneve_set_tunnel);
 	get_fd = bpf_program__fd(skel->progs.ip6geneve_get_tunnel);
-	if (generic_attach(IP6GENEVE_TUNL_DEV1, get_fd, set_fd))
+	if (tc_prog_attach(IP6GENEVE_TUNL_DEV1, get_fd, set_fd))
 		goto done;
 
 	ping_dev0();
@@ -1083,7 +1004,7 @@ static void test_ip6tnl_tunnel(enum ip6tnl_test test)
 		get_fd = bpf_program__fd(skel->progs.ip6ip6_get_tunnel);
 		break;
 	}
-	if (generic_attach(IP6TNL_TUNL_DEV1, get_fd, set_fd))
+	if (tc_prog_attach(IP6TNL_TUNL_DEV1, get_fd, set_fd))
 		goto done;
 
 	ping6_veth0();

-- 
2.51.1.dirty

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