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

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Tue, May 10, 2022 at 2:59 PM Mat Martineau
<mathew.j.martineau@linux.intel.com> wrote:
>
> 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.
>

Ilya actually already generated updated image, and after [0] it should
be used in CI runs. But we'll know for sure with your next MPTCP
submission.

  [0] https://github.com/libbpf/ci/pull/16

> 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