Re: [PATCH bpf-next v7 2/5] bpf: Expose bpf_get_socket_cookie to tracing programs

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

On Wed, Feb 10, 2021 at 3:14 AM Florent Revest <revest@chromium.org> wrote:
>
> This needs a new helper that:
> - can work in a sleepable context (using sock_gen_cookie)
> - takes a struct sock pointer and checks that it's not NULL
>
> Signed-off-by: Florent Revest <revest@chromium.org>
> Acked-by: KP Singh <kpsingh@kernel.org>
> ---

It's customary to send cover letter with patch sets of 2 or more
related patches. It's a good place to explain the motivation of a
patch set. And a good place to ack all patches in one go ;)

Acked-by: Andrii Nakryiko <andrii@kernel.org>


>  include/linux/bpf.h            |  1 +
>  include/uapi/linux/bpf.h       |  8 ++++++++
>  kernel/trace/bpf_trace.c       |  2 ++
>  net/core/filter.c              | 12 ++++++++++++
>  tools/include/uapi/linux/bpf.h |  8 ++++++++
>  5 files changed, 31 insertions(+)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 321966fc35db..d212ae7d9731 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1888,6 +1888,7 @@ extern const struct bpf_func_proto bpf_per_cpu_ptr_proto;
>  extern const struct bpf_func_proto bpf_this_cpu_ptr_proto;
>  extern const struct bpf_func_proto bpf_ktime_get_coarse_ns_proto;
>  extern const struct bpf_func_proto bpf_sock_from_file_proto;
> +extern const struct bpf_func_proto bpf_get_socket_ptr_cookie_proto;
>
>  const struct bpf_func_proto *bpf_tracing_func_proto(
>         enum bpf_func_id func_id, const struct bpf_prog *prog);
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index 0b735c2729b2..a8d9ad543300 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -1673,6 +1673,14 @@ union bpf_attr {
>   *     Return
>   *             A 8-byte long unique number.
>   *
> + * u64 bpf_get_socket_cookie(struct sock *sk)
> + *     Description
> + *             Equivalent to **bpf_get_socket_cookie**\ () helper that accepts
> + *             *sk*, but gets socket from a BTF **struct sock**. This helper
> + *             also works for sleepable programs.
> + *     Return
> + *             A 8-byte long unique number or 0 if *sk* is NULL.
> + *
>   * u32 bpf_get_socket_uid(struct sk_buff *skb)
>   *     Return
>   *             The owner UID of the socket associated to *skb*. If the socket
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 6c0018abe68a..845b2168e006 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1760,6 +1760,8 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
>                 return &bpf_sk_storage_delete_tracing_proto;
>         case BPF_FUNC_sock_from_file:
>                 return &bpf_sock_from_file_proto;
> +       case BPF_FUNC_get_socket_cookie:
> +               return &bpf_get_socket_ptr_cookie_proto;
>  #endif
>         case BPF_FUNC_seq_printf:
>                 return prog->expected_attach_type == BPF_TRACE_ITER ?
> diff --git a/net/core/filter.c b/net/core/filter.c
> index e15d4741719a..57aaed478362 100644
> --- a/net/core/filter.c
> +++ b/net/core/filter.c
> @@ -4631,6 +4631,18 @@ static const struct bpf_func_proto bpf_get_socket_cookie_sock_proto = {
>         .arg1_type      = ARG_PTR_TO_CTX,
>  };
>
> +BPF_CALL_1(bpf_get_socket_ptr_cookie, struct sock *, sk)
> +{
> +       return sk ? sock_gen_cookie(sk) : 0;
> +}
> +
> +const struct bpf_func_proto bpf_get_socket_ptr_cookie_proto = {
> +       .func           = bpf_get_socket_ptr_cookie,
> +       .gpl_only       = false,
> +       .ret_type       = RET_INTEGER,
> +       .arg1_type      = ARG_PTR_TO_BTF_ID_SOCK_COMMON,
> +};
> +
>  BPF_CALL_1(bpf_get_socket_cookie_sock_ops, struct bpf_sock_ops_kern *, ctx)
>  {
>         return __sock_gen_cookie(ctx->sk);
> diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
> index 0b735c2729b2..a8d9ad543300 100644
> --- a/tools/include/uapi/linux/bpf.h
> +++ b/tools/include/uapi/linux/bpf.h
> @@ -1673,6 +1673,14 @@ union bpf_attr {
>   *     Return
>   *             A 8-byte long unique number.
>   *
> + * u64 bpf_get_socket_cookie(struct sock *sk)
> + *     Description
> + *             Equivalent to **bpf_get_socket_cookie**\ () helper that accepts
> + *             *sk*, but gets socket from a BTF **struct sock**. This helper
> + *             also works for sleepable programs.
> + *     Return
> + *             A 8-byte long unique number or 0 if *sk* is NULL.
> + *
>   * u32 bpf_get_socket_uid(struct sk_buff *skb)
>   *     Return
>   *             The owner UID of the socket associated to *skb*. If the socket
> --
> 2.30.0.478.g8a0d178c01-goog
>