netdev - Re: [PATCH bpf-next 3/7] bpf/flow_dissector: support flags in BPF_PROG_TEST

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Date:   Wed, 24 Jul 2019 15:33:09 -0700
From:   Song Liu <liu.song.a23@...il.com>
To:     Stanislav Fomichev <sdf@...gle.com>
Cc:     Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        "David S . Miller" <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Willem de Bruijn <willemb@...gle.com>,
        Petar Penkov <ppenkov@...gle.com>
Subject: Re: [PATCH bpf-next 3/7] bpf/flow_dissector: support flags in BPF_PROG_TEST_RUN

On Wed, Jul 24, 2019 at 10:11 AM Stanislav Fomichev <sdf@...gle.com> wrote:
>
> This will allow us to write tests for those flags.
>
> Cc: Willem de Bruijn <willemb@...gle.com>
> Cc: Petar Penkov <ppenkov@...gle.com>
> Signed-off-by: Stanislav Fomichev <sdf@...gle.com>

Acked-by: Song Liu <songliubraving@...com>

> ---
>  net/bpf/test_run.c | 39 +++++++++++++++++++++++++++++++++++----
>  1 file changed, 35 insertions(+), 4 deletions(-)
>
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index 4e41d15a1098..444a7baed791 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -377,6 +377,22 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
>         return ret;
>  }
>
> +static int verify_user_bpf_flow_keys(struct bpf_flow_keys *ctx)
> +{
> +       /* make sure the fields we don't use are zeroed */
> +       if (!range_is_zero(ctx, 0, offsetof(struct bpf_flow_keys, flags)))
> +               return -EINVAL;
> +
> +       /* flags is allowed */
> +
> +       if (!range_is_zero(ctx, offsetof(struct bpf_flow_keys, flags) +
> +                          FIELD_SIZEOF(struct bpf_flow_keys, flags),
> +                          sizeof(struct bpf_flow_keys)))
> +               return -EINVAL;
> +
> +       return 0;
> +}
> +
>  int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
>                                      const union bpf_attr *kattr,
>                                      union bpf_attr __user *uattr)
> @@ -384,9 +400,11 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
>         u32 size = kattr->test.data_size_in;
>         struct bpf_flow_dissector ctx = {};
>         u32 repeat = kattr->test.repeat;
> +       struct bpf_flow_keys *user_ctx;
>         struct bpf_flow_keys flow_keys;
>         u64 time_start, time_spent = 0;
>         const struct ethhdr *eth;
> +       unsigned int flags = 0;
>         u32 retval, duration;
>         void *data;
>         int ret;
> @@ -395,9 +413,6 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
>         if (prog->type != BPF_PROG_TYPE_FLOW_DISSECTOR)
>                 return -EINVAL;
>
> -       if (kattr->test.ctx_in || kattr->test.ctx_out)
> -               return -EINVAL;
> -
>         if (size < ETH_HLEN)
>                 return -EINVAL;
>
> @@ -410,6 +425,18 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
>         if (!repeat)
>                 repeat = 1;
>
> +       user_ctx = bpf_ctx_init(kattr, sizeof(struct bpf_flow_keys));
> +       if (IS_ERR(user_ctx)) {
> +               kfree(data);
> +               return PTR_ERR(user_ctx);
> +       }
> +       if (user_ctx) {
> +               ret = verify_user_bpf_flow_keys(user_ctx);
> +               if (ret)
> +                       goto out;
> +               flags = user_ctx->flags;
> +       }
> +
>         ctx.flow_keys = &flow_keys;
>         ctx.data = data;
>         ctx.data_end = (__u8 *)data + size;
> @@ -419,7 +446,7 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
>         time_start = ktime_get_ns();
>         for (i = 0; i < repeat; i++) {
>                 retval = bpf_flow_dissect(prog, &ctx, eth->h_proto, ETH_HLEN,
> -                                         size, 0);
> +                                         size, flags);
>
>                 if (signal_pending(current)) {
>                         preempt_enable();
> @@ -450,8 +477,12 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
>
>         ret = bpf_test_finish(kattr, uattr, &flow_keys, sizeof(flow_keys),
>                               retval, duration);
> +       if (!ret)
> +               ret = bpf_ctx_finish(kattr, uattr, user_ctx,
> +                                    sizeof(struct bpf_flow_keys));
>
>  out:
>         kfree(data);
> +       kfree(user_ctx);

nit: it is not really necessary now, but maybe put kfree(user_ctx)
before kfree(data).

>         return ret;
>  }
> --
> 2.22.0.657.g960e92d24f-goog
>