From: Marek Majkowski <marek@cloudflare.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: David Miller <davem@davemloft.net>,
Daniel Borkmann <daniel@iogearbox.net>,
network dev <netdev@vger.kernel.org>,
bpf@vger.kernel.org, kernel-team@fb.com,
linux-security-module@vger.kernel.org, acme@redhat.com,
jamorris@linux.microsoft.com, Jann Horn <jannh@google.com>,
kpsingh@google.com, kernel-team <kernel-team@cloudflare.com>
Subject: Re: [PATCH v6 bpf-next 0/3] Introduce CAP_BPF
Date: Wed, 13 May 2020 11:50:42 +0100 [thread overview]
Message-ID: <CAJPywT+c8uvi2zgUD_jObmi9T6j50THzjQHg-mudNrEC2HuJvg@mail.gmail.com> (raw)
In-Reply-To: <20200513031930.86895-1-alexei.starovoitov@gmail.com>
On Wed, May 13, 2020 at 4:19 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> CAP_BPF solves three main goals:
> 1. provides isolation to user space processes that drop CAP_SYS_ADMIN and switch to CAP_BPF.
> More on this below. This is the major difference vs v4 set back from Sep 2019.
> 2. makes networking BPF progs more secure, since CAP_BPF + CAP_NET_ADMIN
> prevents pointer leaks and arbitrary kernel memory access.
> 3. enables fuzzers to exercise all of the verifier logic. Eventually finding bugs
> and making BPF infra more secure. Currently fuzzers run in unpriv.
> They will be able to run with CAP_BPF.
>
Alexei, looking at this from a user point of view, this looks fine.
I'm slightly worried about REUSEPORT_EBPF. Currently without your
patch, as far as I understand it:
- You can load SOCKET_FILTER and SO_ATTACH_REUSEPORT_EBPF without any
permissions
- For loading BPF_PROG_TYPE_SK_REUSEPORT program and for SOCKARRAY map
creation CAP_SYS_ADMIN is needed. But again, no permissions check for
SO_ATTACH_REUSEPORT_EBPF later.
If I read the patchset correctly, the former SOCKET_FILTER case
remains as it is and is not affected in any way by presence or absence
of CAP_BPF.
The latter case is different. Presence of CAP_BPF is sufficient for
map creation, but not sufficient for loading SK_REUSEPORT program. It
still requires CAP_SYS_ADMIN. I think it's a good opportunity to relax
this CAP_SYS_ADMIN requirement. I think the presence of CAP_BPF should
be sufficient for loading BPF_PROG_TYPE_SK_REUSEPORT.
Our specific use case is simple - we want an application program -
like nginx - to control REUSEPORT programs. We will grant it CAP_BPF,
but we don't want to grant it CAP_SYS_ADMIN.
Marek
next prev parent reply other threads:[~2020-05-13 10:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-13 3:19 [PATCH v6 bpf-next 0/3] Introduce CAP_BPF Alexei Starovoitov
2020-05-13 3:19 ` [PATCH v6 bpf-next 1/3] bpf, capability: " Alexei Starovoitov
2020-05-13 3:19 ` [PATCH v6 bpf-next 2/3] bpf: implement CAP_BPF Alexei Starovoitov
2020-05-13 3:19 ` [PATCH v6 bpf-next 3/3] selftests/bpf: use CAP_BPF and CAP_PERFMON in tests Alexei Starovoitov
2020-05-13 10:50 ` Marek Majkowski [this message]
2020-05-13 17:53 ` [PATCH v6 bpf-next 0/3] Introduce CAP_BPF Alexei Starovoitov
2020-05-13 18:30 ` Marek Majkowski
2020-05-13 18:54 ` Alexei Starovoitov
2020-05-13 21:14 ` Marek Majkowski
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CAJPywT+c8uvi2zgUD_jObmi9T6j50THzjQHg-mudNrEC2HuJvg@mail.gmail.com \
--to=marek@cloudflare.com \
--cc=acme@redhat.com \
--cc=alexei.starovoitov@gmail.com \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=davem@davemloft.net \
--cc=jamorris@linux.microsoft.com \
--cc=jannh@google.com \
--cc=kernel-team@cloudflare.com \
--cc=kernel-team@fb.com \
--cc=kpsingh@google.com \
--cc=linux-security-module@vger.kernel.org \
--cc=netdev@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).