Re: [PATCH bpf-next v3 6/8] selftests: bpf: verify token of struct mptcp_sock

[Mat Martineau <mathew.j.martineau@linux.intel.com>]

On Mon, 2 May 2022, Mat Martineau wrote:

> From: Geliang Tang <geliang.tang@suse.com>
>
> This patch verifies the struct member token of struct mptcp_sock. Add a
> new function get_msk_token() to parse the msk token from the output of
> the command 'ip mptcp monitor', and verify it in verify_msk().
>
> Acked-by: Matthieu Baerts <matthieu.baerts@tessares.net>
> Signed-off-by: Geliang Tang <geliang.tang@suse.com>
> Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
> ---
> .../testing/selftests/bpf/bpf_mptcp_helpers.h |  1 +
> .../testing/selftests/bpf/prog_tests/mptcp.c  | 66 +++++++++++++++++++
> .../testing/selftests/bpf/progs/mptcp_sock.c  |  5 ++
> 3 files changed, 72 insertions(+)
>
> diff --git a/tools/testing/selftests/bpf/bpf_mptcp_helpers.h b/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
> index 18da4cc65e89..87e15810997d 100644
> --- a/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
> +++ b/tools/testing/selftests/bpf/bpf_mptcp_helpers.h
> @@ -9,6 +9,7 @@
> struct mptcp_sock {
> 	struct inet_connection_sock	sk;
>
> +	__u32		token;
> } __attribute__((preserve_access_index));
>
> #endif
> diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/testing/selftests/bpf/prog_tests/mptcp.c
> index 4b40bbdaf91f..c5d96ba81e04 100644
> --- a/tools/testing/selftests/bpf/prog_tests/mptcp.c
> +++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c
> @@ -8,8 +8,11 @@
> struct mptcp_storage {
> 	__u32 invoked;
> 	__u32 is_mptcp;
> +	__u32 token;
> };
>
> +static char monitor_log_path[64];
> +
> static int verify_tsk(int map_fd, int client_fd)
> {
> 	char *msg = "plain TCP socket";
> @@ -36,11 +39,58 @@ static int verify_tsk(int map_fd, int client_fd)
> 	return err;
> }
>
> +/*
> + * Parse the token from the output of 'ip mptcp monitor':
> + *
> + * [       CREATED] token=3ca933d3 remid=0 locid=0 saddr4=127.0.0.1 ...
> + * [       CREATED] token=2ab57040 remid=0 locid=0 saddr4=127.0.0.1 ...
> + */
> +static __u32 get_msk_token(void)
> +{
> +	char *prefix = "[       CREATED] token=";
> +	char buf[BUFSIZ] = {};
> +	__u32 token = 0;
> +	ssize_t len;
> +	int fd;
> +
> +	sync();
> +
> +	fd = open(monitor_log_path, O_RDONLY);
> +	if (CHECK_FAIL(fd < 0)) {
> +		log_err("Failed to open %s", monitor_log_path);
> +		return token;
> +	}
> +
> +	len = read(fd, buf, sizeof(buf));
> +	if (CHECK_FAIL(len < 0)) {
> +		log_err("Failed to read %s", monitor_log_path);
> +		goto err;
> +	}
> +
> +	if (strncmp(buf, prefix, strlen(prefix))) {
> +		log_err("Invalid prefix %s", buf);
> +		goto err;
> +	}
> +
> +	token = strtol(buf + strlen(prefix), NULL, 16);
> +
> +err:
> +	close(fd);
> +	return token;
> +}
> +
> static int verify_msk(int map_fd, int client_fd)
> {
> 	char *msg = "MPTCP subflow socket";
> 	int err = 0, cfd = client_fd;
> 	struct mptcp_storage val;
> +	__u32 token;
> +
> +	token = get_msk_token();
> +	if (token <= 0) {
> +		log_err("Unexpected token %x", token);
> +		return -1;
> +	}
>
> 	if (CHECK_FAIL(bpf_map_lookup_elem(map_fd, &cfd, &val) < 0)) {
> 		perror("Failed to read socket storage");
> @@ -59,6 +109,12 @@ static int verify_msk(int map_fd, int client_fd)
> 		err++;
> 	}
>
> +	if (val.token != token) {
> +		log_err("Unexpected mptcp_sock.token %x != %x",
> +			val.token, token);
> +		err++;
> +	}
> +
> 	return err;
> }
>
> @@ -124,6 +180,7 @@ static int run_test(int cgroup_fd, int server_fd, bool is_mptcp)
>
> void test_base(void)
> {
> +	char cmd[256], tmp_dir[] = "/tmp/XXXXXX";
> 	int server_fd, cgroup_fd;
>
> 	cgroup_fd = test__join_cgroup("/mptcp");
> @@ -141,6 +198,13 @@ void test_base(void)
>
> with_mptcp:
> 	/* with MPTCP */

Geliang, could you add a check here that skips this test (instead of 
failing) if the 'ip mptcp monitor' command is not supported?

Checking the exit status of "ip mptcp help 2>&1 | grep monitor" should 
work.

Thanks,

Mat

> +	if (CHECK_FAIL(!mkdtemp(tmp_dir)))
> +		goto close_cgroup_fd;
> +	snprintf(monitor_log_path, sizeof(monitor_log_path),
> +		 "%s/ip_mptcp_monitor", tmp_dir);
> +	snprintf(cmd, sizeof(cmd), "ip mptcp monitor > %s &", monitor_log_path);
> +	if (CHECK_FAIL(system(cmd)))
> +		goto close_cgroup_fd;
> 	server_fd = start_mptcp_server(AF_INET, NULL, 0, 0);
> 	if (CHECK_FAIL(server_fd < 0))
> 		goto close_cgroup_fd;
> @@ -148,6 +212,8 @@ void test_base(void)
> 	CHECK_FAIL(run_test(cgroup_fd, server_fd, true));
>
> 	close(server_fd);
> +	snprintf(cmd, sizeof(cmd), "rm -rf %s", tmp_dir);
> +	system(cmd);
>
> close_cgroup_fd:
> 	close(cgroup_fd);
> diff --git a/tools/testing/selftests/bpf/progs/mptcp_sock.c b/tools/testing/selftests/bpf/progs/mptcp_sock.c
> index 7b6a25e37de8..c58c191d8416 100644
> --- a/tools/testing/selftests/bpf/progs/mptcp_sock.c
> +++ b/tools/testing/selftests/bpf/progs/mptcp_sock.c
> @@ -12,6 +12,7 @@ extern bool CONFIG_MPTCP __kconfig;
> struct mptcp_storage {
> 	__u32 invoked;
> 	__u32 is_mptcp;
> +	__u32 token;
> };
>
> struct {
> @@ -46,6 +47,8 @@ int _sockops(struct bpf_sock_ops *ctx)
> 					     BPF_SK_STORAGE_GET_F_CREATE);
> 		if (!storage)
> 			return 1;
> +
> +		storage->token = 0;
> 	} else {
> 		if (!CONFIG_MPTCP)
> 			return 1;
> @@ -58,6 +61,8 @@ int _sockops(struct bpf_sock_ops *ctx)
> 					     BPF_SK_STORAGE_GET_F_CREATE);
> 		if (!storage)
> 			return 1;
> +
> +		storage->token = msk->token;
> 	}
> 	storage->invoked++;
> 	storage->is_mptcp = tcp_sk->is_mptcp;
> -- 
> 2.36.0
>
>

--
Mat Martineau
Intel