linux-kernel - Re: [PATCH bpf-next v3 01/17] bpf: add new is_sys_admin_prog

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Message-ID: <CAPhsuW5QMRrvJ_8=RpOv09je180PUHDDy_BciqCKhhKz0Utfsw@mail.gmail.com>
Date:   Fri, 18 Mar 2022 11:07:00 -0700
From:   Song Liu <song@...nel.org>
To:     Benjamin Tissoires <benjamin.tissoires@...hat.com>
Cc:     Greg KH <gregkh@...uxfoundation.org>,
        Jiri Kosina <jikos@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andrii@...nel.org>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...nel.org>, Shuah Khan <shuah@...nel.org>,
        Dave Marchevsky <davemarchevsky@...com>,
        Joe Stringer <joe@...ium.io>, Jonathan Corbet <corbet@....net>,
        Tero Kristo <tero.kristo@...ux.intel.com>,
        open list <linux-kernel@...r.kernel.org>,
        "open list:HID CORE LAYER" <linux-input@...r.kernel.org>,
        Networking <netdev@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        linux-kselftest@...r.kernel.org,
        Linux Doc Mailing List <linux-doc@...r.kernel.org>,
        Sean Young <sean@...s.org>
Subject: Re: [PATCH bpf-next v3 01/17] bpf: add new is_sys_admin_prog_type() helper

On Fri, Mar 18, 2022 at 9:16 AM Benjamin Tissoires
<benjamin.tissoires@...hat.com> wrote:
>
> LIRC_MODE2 does not really need net_admin capability, but only sys_admin.
>
> Extract a new helper for it, it will be also used for the HID bpf
> implementation.
>
> Cc: Sean Young <sean@...s.org>
> Acked-by: Sean Young <sean@...s.org>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>

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

>
> ---
>
> changes in v3:
> - dropped BPF_PROG_TYPE_EXT from the new helper
>
> new in v2
> ---
>  kernel/bpf/syscall.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 9beb585be5a6..b88688264ad0 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2165,7 +2165,6 @@ static bool is_net_admin_prog_type(enum bpf_prog_type prog_type)
>         case BPF_PROG_TYPE_LWT_SEG6LOCAL:
>         case BPF_PROG_TYPE_SK_SKB:
>         case BPF_PROG_TYPE_SK_MSG:
> -       case BPF_PROG_TYPE_LIRC_MODE2:
>         case BPF_PROG_TYPE_FLOW_DISSECTOR:
>         case BPF_PROG_TYPE_CGROUP_DEVICE:
>         case BPF_PROG_TYPE_CGROUP_SOCK:
> @@ -2202,6 +2201,16 @@ static bool is_perfmon_prog_type(enum bpf_prog_type prog_type)
>         }
>  }
>
> +static bool is_sys_admin_prog_type(enum bpf_prog_type prog_type)
> +{
> +       switch (prog_type) {
> +       case BPF_PROG_TYPE_LIRC_MODE2:
> +               return true;
> +       default:
> +               return false;
> +       }
> +}
> +
>  /* last field in 'union bpf_attr' used by this command */
>  #define        BPF_PROG_LOAD_LAST_FIELD core_relo_rec_size
>
> @@ -2252,6 +2261,8 @@ static int bpf_prog_load(union bpf_attr *attr, bpfptr_t uattr)
>                 return -EPERM;
>         if (is_perfmon_prog_type(type) && !perfmon_capable())
>                 return -EPERM;
> +       if (is_sys_admin_prog_type(type) && !capable(CAP_SYS_ADMIN))
> +               return -EPERM;
>
>         /* attach_prog_fd/attach_btf_obj_fd can specify fd of either bpf_prog
>          * or btf, we need to check which one it is
> --
> 2.35.1
>