Re: [PATCH bpf-next v5 4/4] selftests/bpf: Add a selftest for the tracing bpf_get_socket_cookie

[Florent Revest <revest@chromium.org>]

On Wed, Jan 20, 2021 at 8:04 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Wed, Jan 20, 2021 at 9:08 AM KP Singh <kpsingh@kernel.org> wrote:
> >
> > On Tue, Jan 19, 2021 at 5:00 PM Florent Revest <revest@chromium.org> wrote:
> > >
> > > This builds up on the existing socket cookie test which checks whether
> > > the bpf_get_socket_cookie helpers provide the same value in
> > > cgroup/connect6 and sockops programs for a socket created by the
> > > userspace part of the test.
> > >
> > > Adding a tracing program to the existing objects requires a different
> > > attachment strategy and different headers.
> > >
> > > Signed-off-by: Florent Revest <revest@chromium.org>
> >
> > Acked-by: KP Singh <kpsingh@kernel.org>
> >
> > (one minor note, doesn't really need fixing as a part of this though)
> >
> > > ---
> > >  .../selftests/bpf/prog_tests/socket_cookie.c  | 24 +++++++----
> > >  .../selftests/bpf/progs/socket_cookie_prog.c  | 41 ++++++++++++++++---
> > >  2 files changed, 52 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/tools/testing/selftests/bpf/prog_tests/socket_cookie.c b/tools/testing/selftests/bpf/prog_tests/socket_cookie.c
> > > index 53d0c44e7907..e5c5e2ea1deb 100644
> > > --- a/tools/testing/selftests/bpf/prog_tests/socket_cookie.c
> > > +++ b/tools/testing/selftests/bpf/prog_tests/socket_cookie.c
> > > @@ -15,8 +15,8 @@ struct socket_cookie {
> > >
> > >  void test_socket_cookie(void)
> > >  {
> > > +       struct bpf_link *set_link, *update_sockops_link, *update_tracing_link;
> > >         socklen_t addr_len = sizeof(struct sockaddr_in6);
> > > -       struct bpf_link *set_link, *update_link;
> > >         int server_fd, client_fd, cgroup_fd;
> > >         struct socket_cookie_prog *skel;
> > >         __u32 cookie_expected_value;
> > > @@ -39,15 +39,21 @@ void test_socket_cookie(void)
> > >                   PTR_ERR(set_link)))
> > >                 goto close_cgroup_fd;
> > >
> > > -       update_link = bpf_program__attach_cgroup(skel->progs.update_cookie,
> > > -                                                cgroup_fd);
> > > -       if (CHECK(IS_ERR(update_link), "update-link-cg-attach", "err %ld\n",
> > > -                 PTR_ERR(update_link)))
> > > +       update_sockops_link = bpf_program__attach_cgroup(
> > > +               skel->progs.update_cookie_sockops, cgroup_fd);
> > > +       if (CHECK(IS_ERR(update_sockops_link), "update-sockops-link-cg-attach",
> > > +                 "err %ld\n", PTR_ERR(update_sockops_link)))
> > >                 goto free_set_link;
> > >
> > > +       update_tracing_link = bpf_program__attach(
> > > +               skel->progs.update_cookie_tracing);
> > > +       if (CHECK(IS_ERR(update_tracing_link), "update-tracing-link-attach",
> > > +                 "err %ld\n", PTR_ERR(update_tracing_link)))
> > > +               goto free_update_sockops_link;
> > > +
> > >         server_fd = start_server(AF_INET6, SOCK_STREAM, "::1", 0, 0);
> > >         if (CHECK(server_fd < 0, "start_server", "errno %d\n", errno))
> > > -               goto free_update_link;
> > > +               goto free_update_tracing_link;
> > >
> > >         client_fd = connect_to_fd(server_fd, 0);
> > >         if (CHECK(client_fd < 0, "connect_to_fd", "errno %d\n", errno))
> > > @@ -71,8 +77,10 @@ void test_socket_cookie(void)
> > >         close(client_fd);
> > >  close_server_fd:
> > >         close(server_fd);
> > > -free_update_link:
> > > -       bpf_link__destroy(update_link);
> > > +free_update_tracing_link:
> > > +       bpf_link__destroy(update_tracing_link);
> >
> > I don't think this need to block submission unless there are other
> > issues but the
> > bpf_link__destroy can just be called in a single cleanup label because
> > it handles null or
> > erroneous inputs:
> >
> > int bpf_link__destroy(struct bpf_link *link)
> > {
> >     int err = 0;
> >
> >     if (IS_ERR_OR_NULL(link))
> >          return 0;
> > [...]
>
> +1 to KP's point.
>
> Also Florent, how did you test it?
> This test fails in CI and in my manual run:
> ./test_progs -t cook
> libbpf: load bpf program failed: Permission denied
> libbpf: -- BEGIN DUMP LOG ---
> libbpf:
> ; int update_cookie_sockops(struct bpf_sock_ops *ctx)
> 0: (bf) r6 = r1
> ; if (ctx->family != AF_INET6)
> 1: (61) r1 = *(u32 *)(r6 +20)
> ; if (ctx->family != AF_INET6)
> 2: (56) if w1 != 0xa goto pc+21
>  R1_w=inv10 R6_w=ctx(id=0,off=0,imm=0) R10=fp0
> ; if (ctx->op != BPF_SOCK_OPS_TCP_CONNECT_CB)
> 3: (61) r1 = *(u32 *)(r6 +0)
> ; if (ctx->op != BPF_SOCK_OPS_TCP_CONNECT_CB)
> 4: (56) if w1 != 0x3 goto pc+19
>  R1_w=inv3 R6_w=ctx(id=0,off=0,imm=0) R10=fp0
> ; if (!ctx->sk)
> 5: (79) r1 = *(u64 *)(r6 +184)
> ; if (!ctx->sk)
> 6: (15) if r1 == 0x0 goto pc+17
>  R1_w=sock(id=0,ref_obj_id=0,off=0,imm=0) R6_w=ctx(id=0,off=0,imm=0) R10=fp0
> ; p = bpf_sk_storage_get(&socket_cookies, ctx->sk, 0, 0);
> 7: (79) r2 = *(u64 *)(r6 +184)
> ; p = bpf_sk_storage_get(&socket_cookies, ctx->sk, 0, 0);
> 8: (18) r1 = 0xffff888106e41400
> 10: (b7) r3 = 0
> 11: (b7) r4 = 0
> 12: (85) call bpf_sk_storage_get#107
> R2 type=sock_or_null expected=sock_common, sock, tcp_sock, xdp_sock, ptr_
> processed 12 insns (limit 1000000) max_states_per_insn 0 total_states
> 0 peak_states 0 mark_read 0
>
> libbpf: -- END LOG --
> libbpf: failed to load program 'update_cookie_sockops'
> libbpf: failed to load object 'socket_cookie_prog'
> libbpf: failed to load BPF skeleton 'socket_cookie_prog': -4007
> test_socket_cookie:FAIL:socket_cookie_prog__open_and_load skeleton
> open_and_load failed
> #95 socket_cookie:FAIL
> Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED

Oh :| I must have missed something in the rebase, I will fix this and
address KP's comment then. Thanks for the review and sorry for the
waste of time :)