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References: <20201126170212.1749137-1-revest@google.com> <20201126170212.1749137-2-revest@google.com>
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From:   Andrii Nakryiko <andrii.nakryiko@gmail.com>
Date:   Tue, 1 Dec 2020 17:01:10 -0800
Message-ID: <CAEf4Bzb+u4S7toVi64=LKBAhe1K6-+G3S1MYE+mq_TnpDoCg8A@mail.gmail.com>
Subject: Re: [PATCH bpf-next 2/2] bpf: Add a selftest for the tracing bpf_get_socket_cookie
To:     Florent Revest <revest@chromium.org>
Cc:     bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
        Daniel Borkmann <daniel@iogearbox.net>,
        Andrii Nakryiko <andrii@kernel.org>,
        KP Singh <kpsingh@chromium.org>,
        Florent Revest <revest@google.com>,
        open list <linux-kernel@vger.kernel.org>
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On Thu, Nov 26, 2020 at 9:02 AM 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@google.com>
> ---
>  .../selftests/bpf/progs/socket_cookie_prog.c  | 41 ++++++++++++++++---
>  .../selftests/bpf/test_socket_cookie.c        | 18 +++++---
>  2 files changed, 49 insertions(+), 10 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/progs/socket_cookie_prog.c b/tools/testing/selftests/bpf/progs/socket_cookie_prog.c
> index 0cb5656a22b0..a11026aeaaf1 100644
> --- a/tools/testing/selftests/bpf/progs/socket_cookie_prog.c
> +++ b/tools/testing/selftests/bpf/progs/socket_cookie_prog.c
> @@ -1,11 +1,13 @@
>  // SPDX-License-Identifier: GPL-2.0
>  // Copyright (c) 2018 Facebook
>
> -#include <linux/bpf.h>
> -#include <sys/socket.h>
> +#include "vmlinux.h"
>
>  #include <bpf/bpf_helpers.h>
>  #include <bpf/bpf_endian.h>
> +#include <bpf/bpf_tracing.h>
> +
> +#define AF_INET6 10
>
>  struct socket_cookie {
>         __u64 cookie_key;
> @@ -19,6 +21,14 @@ struct {
>         __type(value, struct socket_cookie);
>  } socket_cookies SEC(".maps");
>
> +/*
> + * These three programs get executed in a row on connect() syscalls. The
> + * userspace side of the test creates a client socket, issues a connect() on it
> + * and then checks that the local storage associated with this socket has:
> + * cookie_value == local_port << 8 | 0xFF
> + * The different parts of this cookie_value are appended by those hooks if they
> + * all agree on the output of bpf_get_socket_cookie().
> + */
>  SEC("cgroup/connect6")
>  int set_cookie(struct bpf_sock_addr *ctx)
>  {
> @@ -32,14 +42,14 @@ int set_cookie(struct bpf_sock_addr *ctx)
>         if (!p)
>                 return 1;
>
> -       p->cookie_value = 0xFF;
> +       p->cookie_value = 0xF;
>         p->cookie_key = bpf_get_socket_cookie(ctx);
>
>         return 1;
>  }
>
>  SEC("sockops")
> -int update_cookie(struct bpf_sock_ops *ctx)
> +int update_cookie_sockops(struct bpf_sock_ops *ctx)
>  {
>         struct bpf_sock *sk;
>         struct socket_cookie *p;
> @@ -60,11 +70,32 @@ int update_cookie(struct bpf_sock_ops *ctx)
>         if (p->cookie_key != bpf_get_socket_cookie(ctx))
>                 return 1;
>
> -       p->cookie_value = (ctx->local_port << 8) | p->cookie_value;
> +       p->cookie_value |= (ctx->local_port << 8);
>
>         return 1;
>  }
>
> +SEC("fexit/inet_stream_connect")
> +int BPF_PROG(update_cookie_tracing, struct socket *sock,
> +            struct sockaddr *uaddr, int addr_len, int flags)
> +{
> +       struct socket_cookie *p;
> +
> +       if (uaddr->sa_family != AF_INET6)
> +               return 0;
> +
> +       p = bpf_sk_storage_get(&socket_cookies, sock->sk, 0, 0);
> +       if (!p)
> +               return 0;
> +
> +       if (p->cookie_key != bpf_get_socket_cookie(sock->sk))
> +               return 0;
> +
> +       p->cookie_value |= 0xF0;
> +
> +       return 0;
> +}
> +
>  int _version SEC("version") = 1;

please remove this, while you are at it

>
>  char _license[] SEC("license") = "GPL";
> diff --git a/tools/testing/selftests/bpf/test_socket_cookie.c b/tools/testing/selftests/bpf/test_socket_cookie.c
> index ca7ca87e91aa..0d955c65a4f8 100644
> --- a/tools/testing/selftests/bpf/test_socket_cookie.c
> +++ b/tools/testing/selftests/bpf/test_socket_cookie.c
> @@ -133,6 +133,7 @@ static int run_test(int cgfd)
>         struct bpf_prog_load_attr attr;
>         struct bpf_program *prog;
>         struct bpf_object *pobj;
> +       struct bpf_link *link;
>         const char *prog_name;
>         int server_fd = -1;
>         int client_fd = -1;
> @@ -153,11 +154,18 @@ static int run_test(int cgfd)
>         bpf_object__for_each_program(prog, pobj) {
>                 prog_name = bpf_program__section_name(prog);
>
> -               if (libbpf_attach_type_by_name(prog_name, &attach_type))
> -                       goto err;
> -
> -               err = bpf_prog_attach(bpf_program__fd(prog), cgfd, attach_type,
> -                                     BPF_F_ALLOW_OVERRIDE);
> +               if (bpf_program__is_tracing(prog)) {
> +                       link = bpf_program__attach(prog);
> +                       err = !link;

link is a pointer, so use libbpf_get_error()

> +                       continue;
> +               } else {

else branch is not really necessary, just adds indentation unnecessarily

> +                       if (libbpf_attach_type_by_name(prog_name, &attach_type))
> +                               goto err;
> +
> +                       err = bpf_prog_attach(bpf_program__fd(prog), cgfd,
> +                                             attach_type,
> +                                             BPF_F_ALLOW_OVERRIDE);
> +               }
>                 if (err) {
>                         log_err("Failed to attach prog %s", prog_name);
>                         goto out;
> --
> 2.29.2.454.gaff20da3a2-goog
>