From: "Maciej Żenczykowski" <zenczykowski@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: BPF Mailing List <bpf@vger.kernel.org>,
John Stultz <john.stultz@linaro.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>
Subject: Re: capable_bpf_net_admin()
Date: Thu, 18 Jun 2020 03:19:49 -0700 [thread overview]
Message-ID: <CAHo-Ooz4smKgTDTit4NAnaasUDLJLkX7iRcYouv4KY=AG5SUaA@mail.gmail.com> (raw)
In-Reply-To: <CAADnVQKXbd986SrW2u4nxY-0nNuC7VoVM29=3LeD9potOJTdZQ@mail.gmail.com>
John has all the details. I'm just guessing.
But having actually looked at the code, commit 2c78ee898d8f1 ie.
kernel/bpf/syscall.c: bpf_prog_load()
+ if (is_net_admin_prog_type(type) && !capable(CAP_NET_ADMIN))
+ return -EPERM;
looks fishy, since our bpfloader only has CHOWN SYS_ADMIN, and the
maps/programs it creates/loads are used by netd which only has
NET_ADMIN (but not SYS_ADMIN). Furthermore I don't really want to
grant it NET_ADMIN.
I think this should again be either NET_ADMIN or SYS_ADMIN.
On Thu, Jun 18, 2020 at 12:01 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Wed, Jun 17, 2020 at 11:43 PM Maciej Żenczykowski
> <zenczykowski@gmail.com> wrote:
> >
> > is
> > (SYS_ADMIN || BPF) && NET_ADMIN
> >
> > should this not be
> > SYS_ADMIN || (BPF && NET_ADMIN)
> >
> > ?
>
> capable_bpf_net_admin doesn't exist.
>
> > Won't this cause a just SYS_ADMIN process to fail to load network bpf progs?
>
> if the process has cap_sys_admin it has all privs.
>
> > (I haven't debugged this at all, but John is reporting 5.8-rc1 fails
> > to load bpf progs from Android's bpfloader with EPERM error)
> >
> > Or are we okay with this user space visible behavioural change?
>
> What kind of change? Could you please be more specific?
next prev parent reply other threads:[~2020-06-18 10:20 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-18 6:43 capable_bpf_net_admin() Maciej Żenczykowski
2020-06-18 7:01 ` capable_bpf_net_admin() Alexei Starovoitov
2020-06-18 10:19 ` Maciej Żenczykowski [this message]
2020-06-18 19:03 ` capable_bpf_net_admin() John Stultz
2020-06-18 19:21 ` capable_bpf_net_admin() Maciej Żenczykowski
2020-06-18 19:59 ` [PATCH] restore behaviour of CAP_SYS_ADMIN allowing the loading of net bpf program Maciej Żenczykowski
2020-06-18 21:02 ` Alexei Starovoitov
2020-06-20 21:26 ` [PATCH bpf v2] restore behaviour of CAP_SYS_ADMIN allowing the loading of networking bpf programs Maciej Żenczykowski
2020-06-22 19:44 ` John Stultz
2020-06-24 0:54 ` Alexei Starovoitov
2020-07-06 20:11 ` John Stultz
2020-07-06 20:15 ` Daniel Borkmann
2020-07-06 20:36 ` John Stultz
2020-06-20 1:59 ` capable_bpf_net_admin() John Stultz
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