netdev - Re: [PATCH v4 bpf-next 3/5] bpf: Add bpf_copy_from

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Date:   Mon, 29 Jun 2020 18:18:37 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Daniel Borkmann <daniel@...earbox.net>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH v4 bpf-next 3/5] bpf: Add bpf_copy_from_user() helper.

On Mon, Jun 29, 2020 at 5:35 PM Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
>
> From: Alexei Starovoitov <ast@...nel.org>
>
> Sleepable BPF programs can now use copy_from_user() to access user memory.
>
> Signed-off-by: Alexei Starovoitov <ast@...nel.org>
> ---
>  include/linux/bpf.h            |  1 +
>  include/uapi/linux/bpf.h       | 11 ++++++++++-
>  kernel/bpf/helpers.c           | 22 ++++++++++++++++++++++
>  kernel/trace/bpf_trace.c       |  2 ++
>  tools/include/uapi/linux/bpf.h | 11 ++++++++++-
>  5 files changed, 45 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index e2b1581b2195..c9f27d5fdb7c 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1657,6 +1657,7 @@ extern const struct bpf_func_proto bpf_skc_to_tcp_sock_proto;
>  extern const struct bpf_func_proto bpf_skc_to_tcp_timewait_sock_proto;
>  extern const struct bpf_func_proto bpf_skc_to_tcp_request_sock_proto;
>  extern const struct bpf_func_proto bpf_skc_to_udp6_sock_proto;
> +extern const struct bpf_func_proto bpf_copy_from_user_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 73f9e3f84b77..6b347454dedc 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -3293,6 +3293,13 @@ union bpf_attr {
>   *             Dynamically cast a *sk* pointer to a *udp6_sock* pointer.
>   *     Return
>   *             *sk* if casting is valid, or NULL otherwise.
> + *
> + * long bpf_copy_from_user(void *dst, u32 size, const void *user_ptr)
> + *     Description
> + *             Read *size* bytes from user space address *user_ptr* and store
> + *             the data in *dst*. This is a wrapper of copy_from_user().
> + *     Return
> + *             0 on success, or a negative error in case of failure.
>   */
>  #define __BPF_FUNC_MAPPER(FN)          \
>         FN(unspec),                     \
> @@ -3435,7 +3442,9 @@ union bpf_attr {
>         FN(skc_to_tcp_sock),            \
>         FN(skc_to_tcp_timewait_sock),   \
>         FN(skc_to_tcp_request_sock),    \
> -       FN(skc_to_udp6_sock),
> +       FN(skc_to_udp6_sock),           \
> +       FN(copy_from_user),             \
> +       /* */

Thank you for this! Those trivial merge conflicts due to '\' were
really annoying.

Acked-by: Andrii Nakryiko <andriin@...com>

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