[PATCH bpf-next 5/8] selftests/bpf: Test ksock connect/send combinations

[Mahe Tardy <mahe.tardy@gmail.com>]

Tests more consistently that calling bpf_ksock_send() from unconnected
ksock socket fails and that bpf_ksock_connect() can be called from the
SYSCALL program creating the socket or from the LSM program also calling
bpf_ksock_send().

Signed-off-by: Mahe Tardy <mahe.tardy@gmail.com>
---
 .../testing/selftests/bpf/prog_tests/ksock.c  | 53 +++++++++++++++----
 tools/testing/selftests/bpf/progs/ksock_lsm.c | 32 ++++++++---
 2 files changed, 68 insertions(+), 17 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/ksock.c b/tools/testing/selftests/bpf/prog_tests/ksock.c
index dd6b167623d9..78677bfffdf3 100644
--- a/tools/testing/selftests/bpf/prog_tests/ksock.c
+++ b/tools/testing/selftests/bpf/prog_tests/ksock.c
@@ -17,6 +17,12 @@ struct ksock_test_env {
 	int rfd;
 };

+struct ksock_test_case {
+	const char *name;
+	bool connect_in_syscall;
+	bool connect_in_lsm;
+};
+
 static bool ksock_test_env_setup(struct ksock_test_env *env)
 {
 	struct sockaddr_in addr = {
@@ -55,16 +61,18 @@ static bool ksock_test_env_setup(struct ksock_test_env *env)
 	return false;
 }

-void test_ksock_lsm(void)
+static void test_ksock_lsm_case(const struct ksock_test_case *test)
 {
 	LIBBPF_OPTS(bpf_test_run_opts, opts);
-	struct ksock_test_env env;
 	struct sockaddr_in trigger_addr = {
 		.sin_family = AF_INET,
 		.sin_addr.s_addr = htonl(INADDR_LOOPBACK),
 	};
+	struct ksock_test_env env;
 	struct ksock_lsm *skel;
 	char recv_data[sizeof(skel->data->send_data)] = {};
+	bool connected = test->connect_in_syscall || test->connect_in_lsm;
+	int expected_send_ret = connected ? (int)sizeof(skel->data->send_data) : -EDESTADDRREQ;
 	ssize_t n;
 	int tfd = -1;
 	int err;
@@ -79,6 +87,8 @@ void test_ksock_lsm(void)
 	/* Step 1: Run the setup SYSCALL prog to create the ksock */
 	skel->bss->ipv4_remote = htonl(INADDR_LOOPBACK);
 	skel->bss->remote_port = RECV_PORT;
+	skel->bss->connect_in_syscall = test->connect_in_syscall;
+	skel->bss->connect_in_lsm = test->connect_in_lsm;
 	err = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.ksock_setup),
 				     &opts);
 	if (!ASSERT_OK(err, "ksock_setup run"))
@@ -103,15 +113,25 @@ void test_ksock_lsm(void)
 	if (!ASSERT_OK(err, "trigger bind"))
 		goto fail;

-	/* Step 3: Verify the LSM hook sent the notification */
-	if (!ASSERT_EQ(skel->data->send_ret, sizeof(skel->data->send_data),
-		       "LSM send bytes"))
+	/* Step 3: Verify the operations and received notification, if any. */
+	if (!ASSERT_EQ(skel->data->connect_ret, connected ? 0 : -1, "connect retval"))
+		goto fail;
+
+	if (!ASSERT_EQ(skel->data->send_ret, expected_send_ret, "LSM send retval"))
+		goto fail;
+
+	n = recvfrom(env.rfd, recv_data, sizeof(recv_data),
+		     connected ? 0 : MSG_DONTWAIT, NULL, NULL);
+	if (!connected) {
+		if (ASSERT_EQ(n, -1, "no datagram"))
+			ASSERT_EQ(errno, EAGAIN, "recvfrom errno");
 		goto fail;
+	}

-	n = recvfrom(env.rfd, recv_data, sizeof(recv_data), 0, NULL, NULL);
-	if (ASSERT_EQ(n, sizeof(recv_data), "recvfrom len"))
-		ASSERT_MEMEQ(recv_data, skel->data->send_data, sizeof(recv_data),
-			     "payload match");
+	if (!ASSERT_EQ(n, sizeof(recv_data), "recvfrom len") ||
+	    !ASSERT_MEMEQ(recv_data, skel->data->send_data, sizeof(recv_data),
+			  "payload match"))
+		goto fail;

 fail:
 	if (tfd >= 0)
@@ -124,6 +144,21 @@ void test_ksock_lsm(void)
 	ksock_lsm__destroy(skel);
 }

+void test_ksock_lsm(void)
+{
+	static const struct ksock_test_case tests[] = {
+		{ .name = "unconnected_send" },
+		{ .name = "syscall_connect_send", .connect_in_syscall = true },
+		{ .name = "lsm_connect_send", .connect_in_lsm = true },
+	};
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(tests); i++) {
+		if (test__start_subtest(tests[i].name))
+			test_ksock_lsm_case(&tests[i]);
+	}
+}
+
 void test_ksock_lsm_verifier(void)
 {
 	RUN_TESTS(ksock_lsm_verifier);
diff --git a/tools/testing/selftests/bpf/progs/ksock_lsm.c b/tools/testing/selftests/bpf/progs/ksock_lsm.c
index 9808451098ef..944398ce2852 100644
--- a/tools/testing/selftests/bpf/progs/ksock_lsm.c
+++ b/tools/testing/selftests/bpf/progs/ksock_lsm.c
@@ -13,6 +13,9 @@ char send_data[32] = "hello from bpf ksock";
 __be32 ipv4_remote;
 __u16 remote_port;
 int target_pid;
+bool connect_in_syscall;
+bool connect_in_lsm;
+int connect_ret = -1;
 int send_ret = -1;

 SEC("syscall")
@@ -31,14 +34,15 @@ int ksock_setup(void *ctx)
 	if (!ks)
 		return err;

-	addr.sin.sin_family = AF_INET;
-	addr.sin.sin_port = bpf_htons(remote_port);
-	addr.sin.sin_addr.s_addr = ipv4_remote;
-
-	err = bpf_ksock_connect(ks, &addr, sizeof(addr));
-	if (err) {
-		bpf_ksock_release(ks);
-		return err;
+	if (connect_in_syscall) {
+		addr.sin.sin_family = AF_INET;
+		addr.sin.sin_port = bpf_htons(remote_port);
+		addr.sin.sin_addr.s_addr = ipv4_remote;
+		connect_ret = bpf_ksock_connect(ks, &addr, sizeof(addr));
+		if (connect_ret) {
+			bpf_ksock_release(ks);
+			return connect_ret;
+		}
 	}

 	err = ksock_ctx_insert(ks);
@@ -51,6 +55,7 @@ SEC("lsm.s/socket_bind")
 int BPF_PROG(ksock_socket_bind, struct socket *sock, struct sockaddr *address,
 	     int addrlen, int ret)
 {
+	union bpf_ksock_addr addr = {};
 	struct bpf_ksock *ks;
 	u32 pid = bpf_get_current_pid_tgid() >> 32;

@@ -63,7 +68,18 @@ int BPF_PROG(ksock_socket_bind, struct socket *sock, struct sockaddr *address,
 		return ret;
 	}

+	addr.sin.sin_family = AF_INET;
+	addr.sin.sin_port = bpf_htons(remote_port);
+	addr.sin.sin_addr.s_addr = ipv4_remote;
+
+	if (connect_in_lsm) {
+		connect_ret = bpf_ksock_connect(ks, &addr, sizeof(addr));
+		if (connect_ret)
+			goto out;
+	}
+
 	send_ret = bpf_ksock_send(ks, send_data, sizeof(send_data));
+out:
 	bpf_ksock_release(ks);

 	return ret;
--
2.43.0