selftests/bpf: Test that SO_REUSEPORT can be used with sk_assign helper

We use two programs to check that the new reuseport logic is executed
appropriately.

The first is a TC clsact program which bpf_sk_assigns
the skb to a UDP or TCP socket created by user space. Since the test
communicates via lo we see both directions of packets in the eBPF.
Traffic ingressing to the reuseport socket is identified by looking
at the destination port. For TCP, we additionally need to make sure
that we only assign the initial SYN packets towards our listening
socket. The network stack then creates a request socket which
transitions to ESTABLISHED after the 3WHS.

The second is a reuseport program which shares the fact that
it has been executed with user space. This tells us that the delayed
lookup mechanism is working.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Co-developed-by: Lorenz Bauer <lmb@isovalent.com>
Signed-off-by: Lorenz Bauer <lmb@isovalent.com>
Cc: Joe Stringer <joe@cilium.io>
Link: https://lore.kernel.org/r/20230720-so-reuseport-v6-8-7021b683cdae@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

1 files changed, 199 insertions, 0 deletions

diff --git a/tools/testing/selftests/bpf/prog_tests/assign_reuse.c b/tools/testing/selftests/bpf/prog_tests/assign_reuse.c
new file mode 100644
index 000000000000..989ee4d9785b
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/assign_reuse.c
@@ -0,0 +1,199 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2023 Isovalent */
+#include <uapi/linux/if_link.h>
+#include <test_progs.h>
+
+#include <netinet/tcp.h>
+#include <netinet/udp.h>
+
+#include "network_helpers.h"
+#include "test_assign_reuse.skel.h"
+
+#define NS_TEST "assign_reuse"
+#define LOOPBACK 1
+#define PORT 4443
+
+static int attach_reuseport(int sock_fd, int prog_fd)
+{
+	return setsockopt(sock_fd, SOL_SOCKET, SO_ATTACH_REUSEPORT_EBPF,
+			  &prog_fd, sizeof(prog_fd));
+}
+
+static __u64 cookie(int fd)
+{
+	__u64 cookie = 0;
+	socklen_t cookie_len = sizeof(cookie);
+	int ret;
+
+	ret = getsockopt(fd, SOL_SOCKET, SO_COOKIE, &cookie, &cookie_len);
+	ASSERT_OK(ret, "cookie");
+	ASSERT_GT(cookie, 0, "cookie_invalid");
+
+	return cookie;
+}
+
+static int echo_test_udp(int fd_sv)
+{
+	struct sockaddr_storage addr = {};
+	socklen_t len = sizeof(addr);
+	char buff[1] = {};
+	int fd_cl = -1, ret;
+
+	fd_cl = connect_to_fd(fd_sv, 100);
+	ASSERT_GT(fd_cl, 0, "create_client");
+	ASSERT_EQ(getsockname(fd_cl, (void *)&addr, &len), 0, "getsockname");
+
+	ASSERT_EQ(send(fd_cl, buff, sizeof(buff), 0), 1, "send_client");
+
+	ret = recv(fd_sv, buff, sizeof(buff), 0);
+	if (ret < 0) {
+		close(fd_cl);
+		return errno;
+	}
+
+	ASSERT_EQ(ret, 1, "recv_server");
+	ASSERT_EQ(sendto(fd_sv, buff, sizeof(buff), 0, (void *)&addr, len), 1, "send_server");
+	ASSERT_EQ(recv(fd_cl, buff, sizeof(buff), 0), 1, "recv_client");
+	close(fd_cl);
+	return 0;
+}
+
+static int echo_test_tcp(int fd_sv)
+{
+	char buff[1] = {};
+	int fd_cl = -1, fd_sv_cl = -1;
+
+	fd_cl = connect_to_fd(fd_sv, 100);
+	if (fd_cl < 0)
+		return errno;
+
+	fd_sv_cl = accept(fd_sv, NULL, NULL);
+	ASSERT_GE(fd_sv_cl, 0, "accept_fd");
+
+	ASSERT_EQ(send(fd_cl, buff, sizeof(buff), 0), 1, "send_client");
+	ASSERT_EQ(recv(fd_sv_cl, buff, sizeof(buff), 0), 1, "recv_server");
+	ASSERT_EQ(send(fd_sv_cl, buff, sizeof(buff), 0), 1, "send_server");
+	ASSERT_EQ(recv(fd_cl, buff, sizeof(buff), 0), 1, "recv_client");
+	close(fd_sv_cl);
+	close(fd_cl);
+	return 0;
+}
+
+void run_assign_reuse(int family, int sotype, const char *ip, __u16 port)
+{
+	DECLARE_LIBBPF_OPTS(bpf_tc_hook, tc_hook,
+		.ifindex = LOOPBACK,
+		.attach_point = BPF_TC_INGRESS,
+	);
+	DECLARE_LIBBPF_OPTS(bpf_tc_opts, tc_opts,
+		.handle = 1,
+		.priority = 1,
+	);
+	bool hook_created = false, tc_attached = false;
+	int ret, fd_tc, fd_accept, fd_drop, fd_map;
+	int *fd_sv = NULL;
+	__u64 fd_val;
+	struct test_assign_reuse *skel;
+	const int zero = 0;
+
+	skel = test_assign_reuse__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		goto cleanup;
+
+	skel->rodata->dest_port = port;
+
+	ret = test_assign_reuse__load(skel);
+	if (!ASSERT_OK(ret, "skel_load"))
+		goto cleanup;
+
+	ASSERT_EQ(skel->bss->sk_cookie_seen, 0, "cookie_init");
+
+	fd_tc = bpf_program__fd(skel->progs.tc_main);
+	fd_accept = bpf_program__fd(skel->progs.reuse_accept);
+	fd_drop = bpf_program__fd(skel->progs.reuse_drop);
+	fd_map = bpf_map__fd(skel->maps.sk_map);
+
+	fd_sv = start_reuseport_server(family, sotype, ip, port, 100, 1);
+	if (!ASSERT_NEQ(fd_sv, NULL, "start_reuseport_server"))
+		goto cleanup;
+
+	ret = attach_reuseport(*fd_sv, fd_drop);
+	if (!ASSERT_OK(ret, "attach_reuseport"))
+		goto cleanup;
+
+	fd_val = *fd_sv;
+	ret = bpf_map_update_elem(fd_map, &zero, &fd_val, BPF_NOEXIST);
+	if (!ASSERT_OK(ret, "bpf_sk_map"))
+		goto cleanup;
+
+	ret = bpf_tc_hook_create(&tc_hook);
+	if (ret == 0)
+		hook_created = true;
+	ret = ret == -EEXIST ? 0 : ret;
+	if (!ASSERT_OK(ret, "bpf_tc_hook_create"))
+		goto cleanup;
+
+	tc_opts.prog_fd = fd_tc;
+	ret = bpf_tc_attach(&tc_hook, &tc_opts);
+	if (!ASSERT_OK(ret, "bpf_tc_attach"))
+		goto cleanup;
+	tc_attached = true;
+
+	if (sotype == SOCK_STREAM)
+		ASSERT_EQ(echo_test_tcp(*fd_sv), ECONNREFUSED, "drop_tcp");
+	else
+		ASSERT_EQ(echo_test_udp(*fd_sv), EAGAIN, "drop_udp");
+	ASSERT_EQ(skel->bss->reuseport_executed, 1, "program executed once");
+
+	skel->bss->sk_cookie_seen = 0;
+	skel->bss->reuseport_executed = 0;
+	ASSERT_OK(attach_reuseport(*fd_sv, fd_accept), "attach_reuseport(accept)");
+
+	if (sotype == SOCK_STREAM)
+		ASSERT_EQ(echo_test_tcp(*fd_sv), 0, "echo_tcp");
+	else
+		ASSERT_EQ(echo_test_udp(*fd_sv), 0, "echo_udp");
+
+	ASSERT_EQ(skel->bss->sk_cookie_seen, cookie(*fd_sv),
+		  "cookie_mismatch");
+	ASSERT_EQ(skel->bss->reuseport_executed, 1, "program executed once");
+cleanup:
+	if (tc_attached) {
+		tc_opts.flags = tc_opts.prog_fd = tc_opts.prog_id = 0;
+		ret = bpf_tc_detach(&tc_hook, &tc_opts);
+		ASSERT_OK(ret, "bpf_tc_detach");
+	}
+	if (hook_created) {
+		tc_hook.attach_point = BPF_TC_INGRESS | BPF_TC_EGRESS;
+		bpf_tc_hook_destroy(&tc_hook);
+	}
+	test_assign_reuse__destroy(skel);
+	free_fds(fd_sv, 1);
+}
+
+void test_assign_reuse(void)
+{
+	struct nstoken *tok = NULL;
+
+	SYS(out, "ip netns add %s", NS_TEST);
+	SYS(cleanup, "ip -net %s link set dev lo up", NS_TEST);
+
+	tok = open_netns(NS_TEST);
+	if (!ASSERT_OK_PTR(tok, "netns token"))
+		return;
+
+	if (test__start_subtest("tcpv4"))
+		run_assign_reuse(AF_INET, SOCK_STREAM, "127.0.0.1", PORT);
+	if (test__start_subtest("tcpv6"))
+		run_assign_reuse(AF_INET6, SOCK_STREAM, "::1", PORT);
+	if (test__start_subtest("udpv4"))
+		run_assign_reuse(AF_INET, SOCK_DGRAM, "127.0.0.1", PORT);
+	if (test__start_subtest("udpv6"))
+		run_assign_reuse(AF_INET6, SOCK_DGRAM, "::1", PORT);
+
+cleanup:
+	close_netns(tok);
+	SYS_NOFAIL("ip netns delete %s", NS_TEST);
+out:
+	return;
+}