selftests/bpf: Add tests for bpf_redirect_peer with BPF_F_EGRESS

Extend redirect tests to cover bpf_redirect_peer(BPF_F_EGRESS). SRC
redirects to DST using bpf_redirect_peer(BPF_F_EGRESS) then traffic is
hairpinned into DST using bpf_redirect.

Signed-off-by: Jordan Rife <jordan@jrife.io>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Paul Chaignon <paul.chaignon@gmail.com>
Link: https://lore.kernel.org/r/20260618182035.43811-3-jordan@jrife.io
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 90 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/tc_redirect.c b/tools/testing/selftests/bpf/prog_tests/tc_redirect.c
index 64fbda082309..af8968b89ad7 100644
--- a/tools/testing/selftests/bpf/prog_tests/tc_redirect.c
+++ b/tools/testing/selftests/bpf/prog_tests/tc_redirect.c
@@ -192,6 +192,8 @@ static int create_netkit(int mode, char *prim, char *peer)
 	req.n.nlmsg_len += sizeof(struct ifinfomsg);
 	addattr_l(&req.n, sizeof(req), IFLA_IFNAME, peer, strlen(peer));
 	addattr_nest_end(&req.n, peer_info);
+	addattr32(&req.n, sizeof(req), IFLA_NETKIT_SCRUB,
+		  NETKIT_SCRUB_NONE);
 	addattr_nest_end(&req.n, data);
 	addattr_nest_end(&req.n, linkinfo);
 
@@ -405,6 +407,24 @@ fail:
 	return -1;
 }
 
+static struct bpf_link *netns_attach_nk(const char *ns, int ifindex,
+					struct bpf_program *prog)
+{
+	LIBBPF_OPTS(bpf_netkit_opts, optl);
+	struct nstoken *nstoken = NULL;
+	struct bpf_link *link = NULL;
+
+	nstoken = open_netns(ns);
+	if (!ASSERT_OK_PTR(nstoken, "setns"))
+		goto cleanup;
+
+	link = bpf_program__attach_netkit(prog, ifindex, &optl);
+cleanup:
+	if (nstoken)
+		close_netns(nstoken);
+	return link;
+}
+
 static void test_tcp(int family, const char *addr, __u16 port)
 {
 	int listen_fd = -1, accept_fd = -1, client_fd = -1;
@@ -1082,6 +1102,53 @@ done:
 	close_netns(nstoken);
 }
 
+static void test_tc_redirect_peer_ing(struct netns_setup_result *setup_result)
+{
+	struct test_tc_peer *skel;
+	struct nstoken *nstoken;
+	int err;
+
+	nstoken = open_netns(NS_FWD);
+	if (!ASSERT_OK_PTR(nstoken, "setns fwd"))
+		return;
+
+	skel = test_tc_peer__open();
+	if (!ASSERT_OK_PTR(skel, "test_tc_peer__open"))
+		goto done;
+
+	skel->rodata->IFINDEX_SRC = setup_result->ifindex_src_fwd;
+	skel->rodata->IFINDEX_DST = setup_result->ifindex_dst_fwd;
+	ASSERT_EQ(bpf_program__set_expected_attach_type(skel->progs.tc_src_ing,
+		  BPF_NETKIT_PRIMARY), 0, "src_prog_attach_type");
+	ASSERT_EQ(bpf_program__set_expected_attach_type(skel->progs.tc_dst_ing,
+		  BPF_NETKIT_PRIMARY), 0, "dst_prog_attach_type");
+
+	err = test_tc_peer__load(skel);
+	if (!ASSERT_OK(err, "test_tc_peer__load"))
+		goto done;
+
+	skel->links.tc_src_ing = netns_attach_nk(NS_SRC,
+						 setup_result->ifindex_src,
+						 skel->progs.tc_src_ing);
+	if (!ASSERT_OK_PTR(skel->links.tc_src_ing, "attach_src"))
+		goto done;
+	skel->links.tc_dst_ing = netns_attach_nk(NS_DST,
+						 setup_result->ifindex_dst,
+						 skel->progs.tc_dst_ing);
+	if (!ASSERT_OK_PTR(skel->links.tc_dst_ing, "attach_dst"))
+		goto done;
+
+	if (!ASSERT_OK(set_forwarding(false), "disable forwarding"))
+		goto done;
+
+	test_connectivity();
+
+done:
+	if (skel)
+		test_tc_peer__destroy(skel);
+	close_netns(nstoken);
+}
+
 static int tun_open(char *name)
 {
 	struct ifreq ifr;
@@ -1280,6 +1347,7 @@ static void *test_tc_redirect_run_tests(void *arg)
 
 	RUN_TEST(tc_redirect_peer, MODE_VETH);
 	RUN_TEST(tc_redirect_peer, MODE_NETKIT);
+	RUN_TEST(tc_redirect_peer_ing, MODE_NETKIT);
 	RUN_TEST(tc_redirect_peer_l3, MODE_VETH);
 	RUN_TEST(tc_redirect_peer_l3, MODE_NETKIT);
 	RUN_TEST(tc_redirect_neigh, MODE_VETH);
diff --git a/tools/testing/selftests/bpf/progs/test_tc_peer.c b/tools/testing/selftests/bpf/progs/test_tc_peer.c
index 365eacb5dc34..cfb9ef7f467c 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_peer.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_peer.c
@@ -35,6 +35,28 @@ int tc_src(struct __sk_buff *skb)
 }
 
 SEC("tc")
+int tc_dst_ing(struct __sk_buff *skb)
+{
+	if (!skb->mark) {
+		skb->mark = 0x1;
+		return bpf_redirect_peer(IFINDEX_SRC, BPF_F_EGRESS);
+	}
+
+	return bpf_redirect(IFINDEX_DST, 0);
+}
+
+SEC("tc")
+int tc_src_ing(struct __sk_buff *skb)
+{
+	if (!skb->mark) {
+		skb->mark = 0x1;
+		return bpf_redirect_peer(IFINDEX_DST, BPF_F_EGRESS);
+	}
+
+	return bpf_redirect(IFINDEX_SRC, 0);
+}
+
+SEC("tc")
 int tc_dst_l3(struct __sk_buff *skb)
 {
 	return bpf_redirect(IFINDEX_SRC, 0);