linux-kernel - Re: [PATCH ghak124 v3] audit: log nftables configuration change events

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Message-ID: <20210212204828.GL3141668@madcap2.tricolour.ca>
Date:   Fri, 12 Feb 2021 15:48:28 -0500
From:   Richard Guy Briggs <rgb@...hat.com>
To:     Paul Moore <paul@...l-moore.com>
Cc:     Phil Sutter <phil@....cc>,
        Linux-Audit Mailing List <linux-audit@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        netfilter-devel@...r.kernel.org, sgrubb@...hat.com,
        Ondrej Mosnacek <omosnace@...hat.com>, fw@...len.de,
        twoerner@...hat.com, Eric Paris <eparis@...isplace.org>,
        tgraf@...radead.org
Subject: Re: [PATCH ghak124 v3] audit: log nftables configuration change
 events

On 2021-02-11 15:26, Richard Guy Briggs wrote:
> On 2021-02-11 11:29, Paul Moore wrote:
> > On Thu, Feb 11, 2021 at 10:16 AM Phil Sutter <phil@....cc> wrote:
> > > Hi,
> > >
> > > On Thu, Jun 04, 2020 at 09:20:49AM -0400, Richard Guy Briggs wrote:
> > > > iptables, ip6tables, arptables and ebtables table registration,
> > > > replacement and unregistration configuration events are logged for the
> > > > native (legacy) iptables setsockopt api, but not for the
> > > > nftables netlink api which is used by the nft-variant of iptables in
> > > > addition to nftables itself.
> > > >
> > > > Add calls to log the configuration actions in the nftables netlink api.
> > >
> > > As discussed offline already, these audit notifications are pretty hefty
> > > performance-wise. In an internal report, 300% restore time of a ruleset
> > > containing 70k set elements is measured.
> > 
> > If you're going to reference offline/off-list discussions in a post to
> > a public list, perhaps the original discussion shouldn't have been
> > off-list ;)  If you don't involve us in the discussion, we have to
> > waste a lot of time getting caught up.
> 
> Here's part of that discussion:
> 	https://bugzilla.redhat.com/show_bug.cgi?id=1918013

Here's the rest:
	 https://bugzilla.redhat.com/show_bug.cgi?id=1921624

> > > If I'm not mistaken, iptables emits a single audit log per table, ipset
> > > doesn't support audit at all. So I wonder how much audit logging is
> > > required at all (for certification or whatever reason). How much
> > > granularity is desired?
> > 
> > That's a question for the people who track these certification
> > requirements, which is thankfully not me at the moment.  Unless
> > somebody else wants to speak up, Steve Grubb is probably the only
> > person who tracks that sort of stuff and comments here.
> > 
> > I believe the netfilter auditing was mostly a nice-to-have bit of
> > functionality to help add to the completeness of the audit logs, but I
> > could very easily be mistaken.  Richard put together those patches, he
> > can probably provide the background/motivation for the effort.
> 
> It was added because an audit test that normally produced records from
> iptables on one distro stopped producing any records on another.
> Investigation led to the fact that on the first it was using
> iptables-legacy API and on the other it was using iptables-nft API.
> 
> > > I personally would notify once per transaction. This is easy and quick.
> 
> This was the goal.  iptables was atomic.  nftables appears to no longer
> be so.  If I have this wrong, please show how that works.
> 
> > > Once per table or chain should be acceptable, as well. At the very
> > > least, we should not have to notify once per each element. This is the
> > > last resort of fast ruleset adjustments. If we lose it, people are
> > > better off with ipset IMHO.
> > >
> > > Unlike nft monitor, auditd is not designed to be disabled "at will". So
> > > turning it off for performance-critical workloads is no option.
> 
> If it were to be disabled "at will" it would defeat the purpose of
> audit.  Those records can already be filtered, or audit can be disabled,
> but let us look at rationalizing the current nftables records first.
> 
> > Patches are always welcome, but it might be wise to get to the bottom
> > of the certification requirements first.
> > 
> > paul moore
> 
> - RGB

- RGB

--
Richard Guy Briggs <rgb@...hat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635