Re: [PATCH bpf-next v2 01/28] bpf: add new is_sys_admin_prog_type() helper

Song Liu
2022-03-04T23:12:41Z

On Fri, Mar 4, 2022 at 9:30 AM Benjamin Tissoires
<benjamin.tissoires@redhat.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@mess.org>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
>
> ---
>
> new in v2
> ---
> kernel/bpf/syscall.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index db402ebc5570..cc570891322b 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 +2201,17 @@ 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:
> + case BPF_PROG_TYPE_EXT: /* extends any prog */
> + return true;
> + default:
> + return false;
> + }
> +}

I am not sure whether we should do this. This is a behavior change, that may
break some user space. Also, BPF_PROG_TYPE_EXT is checked in
is_perfmon_prog_type(), and this change will make that case useless.

Thanks,
Song …