bpf.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Lorenz Bauer <lmb@cloudflare.com>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>,
	kernel-team <kernel-team@cloudflare.com>,
	Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Jakub Sitnicki <jakub@cloudflare.com>
Subject: Re: [PATCH 0/5] Return fds from privileged sockhash/sockmap lookup
Date: Fri, 13 Mar 2020 10:48:57 +0000	[thread overview]
Message-ID: <CACAyw98cp2we2w_L=YgEj+BbCqA5_3HvSML1VZzyNeF8mVfEEQ@mail.gmail.com> (raw)
In-Reply-To: <20200312175828.xenznhgituyi25kj@ast-mbp>

On Thu, 12 Mar 2020 at 17:58, Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
> but there it goes through ptrace checks and lsm hoooks, whereas here similar
> security model cannot be enforced. bpf prog can put any socket into sockmap and
> from bpf_lookup_elem side there is no way to figure out the owner task of the
> socket to do ptrace checks. Just doing it all under CAP_NET_ADMIN is not a
> great security answer.

Reading between the lines, you're concerned about something like a sock ops
program "stealing" the socket and putting it in a sockmap, to be retrieved by an
attacker later on?

How is that different than BPF_MAP_GET_FD_BY_ID, except that it's CAP_SYS_ADMIN?

> but bpf side may still need to insert them into old.
> you gonna solve it with a flag for the prog to stop doing its job?
> Or the prog will know that it needs to put sockets into second map now?
> It's really the same problem as with classic so_reuseport
> which was solved with BPF_MAP_TYPE_REUSEPORT_SOCKARRAY.

We don't modify the sockmap from eBPF:
   receive a packet -> lookup sk in sockmap based on packet -> redirect

Why do you think we'll have to insert sockets from BPF?

> I think sockmap needs a redesign. Consider that today all sockets can be in any
> number of sk_local_storage pseudo maps. They are 'defragmented' and resizable.
> I think plugging socket redirect to use sk_local_storage-like infra is the
> answer.

Maybe Jakub can speak more to this but I don't see how this solves our problem.
We need a way to get at struct sk * from an eBPF program that runs on
an skb context,
to make BPF socket dispatch feasible. How would we use
sk_local_storage if we don't
have a sk?

Lorenz Bauer  |  Systems Engineer
6th Floor, County Hall/The Riverside Building, SE1 7PB, UK


  parent reply	other threads:[~2020-03-13 10:49 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-10 17:47 [PATCH 0/5] Return fds from privileged sockhash/sockmap lookup Lorenz Bauer
2020-03-10 17:47 ` [PATCH 1/5] bpf: add map_copy_value hook Lorenz Bauer
2020-03-10 17:47 ` [PATCH 2/5] bpf: convert queue and stack map to map_copy_value Lorenz Bauer
2020-03-11 14:00   ` Jakub Sitnicki
2020-03-11 22:31     ` John Fastabend
2020-03-10 17:47 ` [PATCH 3/5] bpf: convert sock map and hash " Lorenz Bauer
2020-03-11 13:55   ` Jakub Sitnicki
2020-03-10 17:47 ` [PATCH 4/5] bpf: sockmap, sockhash: return file descriptors from privileged lookup Lorenz Bauer
2020-03-11 23:27   ` John Fastabend
2020-03-17 10:17     ` Lorenz Bauer
2020-03-17 15:18   ` Jakub Sitnicki
2020-03-17 18:16     ` John Fastabend
2020-03-10 17:47 ` [PATCH 5/5] bpf: sockmap, sockhash: test looking up fds Lorenz Bauer
2020-03-11 13:52   ` Jakub Sitnicki
2020-03-11 17:24     ` Lorenz Bauer
2020-03-11 13:44 ` [PATCH 0/5] Return fds from privileged sockhash/sockmap lookup Jakub Sitnicki
2020-03-11 22:40   ` John Fastabend
2020-03-12  1:58 ` Alexei Starovoitov
2020-03-12  9:16   ` Lorenz Bauer
2020-03-12 17:58     ` Alexei Starovoitov
2020-03-12 19:32       ` John Fastabend
2020-03-13 11:03         ` Lorenz Bauer
2020-03-13 10:48       ` Lorenz Bauer [this message]
2020-03-14  2:58         ` Alexei Starovoitov
2020-03-17  9:55           ` Lorenz Bauer
2020-03-17 19:05             ` John Fastabend
2020-03-20 15:12               ` Lorenz Bauer
2020-04-07  3:08                 ` Alexei Starovoitov

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:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CACAyw98cp2we2w_L=YgEj+BbCqA5_3HvSML1VZzyNeF8mVfEEQ@mail.gmail.com' \
    --to=lmb@cloudflare.com \
    --cc=alexei.starovoitov@gmail.com \
    --cc=bpf@vger.kernel.org \
    --cc=daniel@iogearbox.net \
    --cc=jakub@cloudflare.com \
    --cc=kernel-team@cloudflare.com \
    --cc=netdev@vger.kernel.org \


* 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).