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From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrey Ignatov <rdna@fb.com>, Andrii Nakryiko <andriin@fb.com>,
	bpf <bpf@vger.kernel.org>, Networking <netdev@vger.kernel.org>,
	Alexei Starovoitov <ast@fb.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH v3 bpf-next 1/4] bpf: implement bpf_link-based cgroup BPF program attachment
Date: Mon, 30 Mar 2020 18:06:14 -0700	[thread overview]
Message-ID: <CAEf4BzZ2-a+m_wV2sffKMQ1Zi7wREvV=mkBmQC4ExQsi9zpbww@mail.gmail.com> (raw)
In-Reply-To: <20200331003833.2cimhnn5scfroyv7@ast-mbp>

On Mon, Mar 30, 2020 at 5:38 PM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Mon, Mar 30, 2020 at 05:05:13PM -0700, Andrey Ignatov wrote:
> > >
> > > +#define BPF_LINK_CREATE_LAST_FIELD link_create.flags
> > > +static int link_create(union bpf_attr *attr)
> > > +{
> >
> > From what I see this function does not check any capability whether the
> > existing bpf_prog_attach() checks for CAP_NET_ADMIN.
>
> Great catch! It's a bug.
> I fixed it up.

Thanks!

>
> > This is pretty importnant difference but I don't see it clarified in the
> > commit message or discussed (or I missed it?).

Yeah, not intentional, thanks for catching!

> >
> > Having a way to attach cgroup bpf prog by non-priv users is actually
> > helpful in some use-cases, e.g. systemd required patching in the past to
> > make it work with user (non-priv) sessions, see [0].
> >
> > But in other cases it's also useful to limit the ability to attach
> > programs to a cgroup while using bpf_link so that only the thing that
> > controls cgroup setup can attach but not any non-priv process running in
> > that cgroup. How is this use-case covered in BPF_LINK_CREATE?
> >
> >
> > [0] https://github.com/systemd/systemd/pull/12745
>
> yeah. we need to resurrect the discussion around CAP_BPF.
>
> PS
> pls trim your replies.

  reply	other threads:[~2020-03-31  1:06 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-30  2:59 [PATCH v3 bpf-next 0/4] Add support for cgroup bpf_link Andrii Nakryiko
2020-03-30  2:59 ` [PATCH v3 bpf-next 1/4] bpf: implement bpf_link-based cgroup BPF program attachment Andrii Nakryiko
2020-03-31  0:05   ` Andrey Ignatov
2020-03-31  0:38     ` Alexei Starovoitov
2020-03-31  1:06       ` Andrii Nakryiko [this message]
2020-03-30  2:59 ` [PATCH v3 bpf-next 2/4] bpf: implement bpf_prog replacement for an active bpf_cgroup_link Andrii Nakryiko
2020-03-30  3:00 ` [PATCH v3 bpf-next 3/4] libbpf: add support for bpf_link-based cgroup attachment Andrii Nakryiko
2020-03-30  3:00 ` [PATCH v3 bpf-next 4/4] selftests/bpf: test FD-based " Andrii Nakryiko
2020-03-30 14:49 ` [PATCH v3 bpf-next 0/4] Add support for cgroup bpf_link David Ahern
2020-03-30 20:20   ` Andrii Nakryiko
2020-03-30 20:45     ` David Ahern
2020-03-30 20:50       ` Alexei Starovoitov
2020-03-30 22:50       ` Alexei Starovoitov
2020-03-30 23:43         ` David Ahern
2020-03-31  0:32           ` Alexei Starovoitov
2020-03-31  0:57             ` David Ahern
2020-03-31  1:17               ` Alexei Starovoitov
2020-04-01  1:42                 ` David Ahern
2020-04-01  2:04                   ` Alexei Starovoitov
2020-03-31  3:54               ` Andrii Nakryiko
2020-03-31 16:54                 ` David Ahern
2020-03-31 17:03                   ` Andrii Nakryiko
2020-03-31 17:11                   ` Alexei Starovoitov
2020-03-31 21:51                 ` Edward Cree
2020-03-31 22:44                   ` David Ahern
2020-04-01  0:45                     ` Andrii Nakryiko
2020-04-01  0:22                   ` Andrii Nakryiko
2020-04-01 14:26                     ` Edward Cree
2020-04-01 17:39                       ` Andrii Nakryiko

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