netdev - Re: [bpf-next PATCH v3 4/5] bpf: selftests, add sk

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Date:   Thu, 21 May 2020 11:51:51 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     John Fastabend <john.fastabend@...il.com>
Cc:     Yonghong Song <yhs@...com>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Lorenz Bauer <lmb@...udflare.com>, bpf <bpf@...r.kernel.org>,
        Jakub Sitnicki <jakub@...udflare.com>,
        Networking <netdev@...r.kernel.org>
Subject: Re: [bpf-next PATCH v3 4/5] bpf: selftests, add sk_msg helpers load
 and attach test

On Thu, May 21, 2020 at 7:36 AM John Fastabend <john.fastabend@...il.com> wrote:
>
> The test itself is not particularly useful but it encodes a common
> pattern we have.
>
> Namely do a sk storage lookup then depending on data here decide if
> we need to do more work or alternatively allow packet to PASS. Then
> if we need to do more work consult task_struct for more information
> about the running task. Finally based on this additional information
> drop or pass the data. In this case the suspicious check is not so
> realisitic but it encodes the general pattern and uses the helpers
> so we test the workflow.
>
> This is a load test to ensure verifier correctly handles this case.
>
> Signed-off-by: John Fastabend <john.fastabend@...il.com>
> ---
>  .../selftests/bpf/prog_tests/sockmap_basic.c       |   57 ++++++++++++++++++++
>  .../selftests/bpf/progs/test_skmsg_load_helpers.c  |   48 +++++++++++++++++
>  2 files changed, 105 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/progs/test_skmsg_load_helpers.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> index aa43e0b..cacb4ad 100644
> --- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
> @@ -1,13 +1,46 @@
>  // SPDX-License-Identifier: GPL-2.0
>  // Copyright (c) 2020 Cloudflare
> +#include <error.h>
>
>  #include "test_progs.h"
> +#include "test_skmsg_load_helpers.skel.h"
>
>  #define TCP_REPAIR             19      /* TCP sock is under repair right now */
>
>  #define TCP_REPAIR_ON          1
>  #define TCP_REPAIR_OFF_NO_WP   -1      /* Turn off without window probes */
>
> +#define _FAIL(errnum, fmt...)                                                  \
> +       ({                                                                     \
> +               error_at_line(0, (errnum), __func__, __LINE__, fmt);           \
> +               CHECK_FAIL(true);                                              \
> +       })
> +#define FAIL(fmt...) _FAIL(0, fmt)
> +#define FAIL_ERRNO(fmt...) _FAIL(errno, fmt)
> +#define FAIL_LIBBPF(err, msg)                                                  \
> +       ({                                                                     \
> +               char __buf[MAX_STRERR_LEN];                                    \
> +               libbpf_strerror((err), __buf, sizeof(__buf));                  \
> +               FAIL("%s: %s", (msg), __buf);                                  \
> +       })
> +
> +#define xbpf_prog_attach(prog, target, type, flags)                            \
> +       ({                                                                     \
> +               int __ret =                                                    \
> +                       bpf_prog_attach((prog), (target), (type), (flags));    \
> +               if (__ret == -1)                                               \
> +                       FAIL_ERRNO("prog_attach(" #type ")");                  \
> +               __ret;                                                         \
> +       })
> +
> +#define xbpf_prog_detach2(prog, target, type)                                  \
> +       ({                                                                     \
> +               int __ret = bpf_prog_detach2((prog), (target), (type));        \
> +               if (__ret == -1)                                               \
> +                       FAIL_ERRNO("prog_detach2(" #type ")");                 \
> +               __ret;                                                         \
> +       })

I'm not convinced we need these macro, can you please just use CHECKs?
I'd rather not learn each specific test's custom macros.

> +
>  static int connected_socket_v4(void)
>  {
>         struct sockaddr_in addr = {
> @@ -70,10 +103,34 @@ static void test_sockmap_create_update_free(enum bpf_map_type map_type)
>         close(s);
>  }
>
> +static void test_skmsg_helpers(enum bpf_map_type map_type)
> +{
> +       struct test_skmsg_load_helpers *skel;
> +       int err, map, verdict;
> +
> +       skel = test_skmsg_load_helpers__open_and_load();
> +       if (!skel) {
> +               FAIL("skeleton open/load failed");
> +               return;
> +       }
> +
> +       verdict = bpf_program__fd(skel->progs.prog_msg_verdict);
> +       map = bpf_map__fd(skel->maps.sock_map);
> +
> +       err = xbpf_prog_attach(verdict, map, BPF_SK_MSG_VERDICT, 0);
> +       if (err)
> +               return;
> +       xbpf_prog_detach2(verdict, map, BPF_SK_MSG_VERDICT);

no cleanup in this test, at all

> +}
> +

[...]

> +
> +int _version SEC("version") = 1;

version not needed

> +char _license[] SEC("license") = "GPL";
>