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

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Message-ID: <20210219062651.GR2015948@madcap2.tricolour.ca>
Date:   Fri, 19 Feb 2021 01:26:51 -0500
From:   Richard Guy Briggs <rgb@...hat.com>
To:     Florian Westphal <fw@...len.de>
Cc:     Phil Sutter <phil@....cc>, LKML <linux-kernel@...r.kernel.org>,
        Linux-Audit Mailing List <linux-audit@...hat.com>,
        netfilter-devel@...r.kernel.org, twoerner@...hat.com,
        Eric Paris <eparis@...isplace.org>, tgraf@...radead.org
Subject: Re: [PATCH ghak124 v3] audit: log nftables configuration change
 events

On 2021-02-18 23:42, Florian Westphal wrote:
> Richard Guy Briggs <rgb@...hat.com> wrote:
> > > If they appear in a batch tehy will be ignored, if the batch consists of
> > > such non-modifying ops only then nf_tables_commit() returns early
> > > because the transaction list is empty (nothing to do/change).
> > 
> > Ok, one little inconvenient question: what about GETOBJ_RESET?  That
> > looks like a hybrid that modifies kernel table counters and reports
> > synchronously.  That could be a special case call in
> > nf_tables_dump_obj() and nf_tables_getobj().  Will that cause a storm
> > per commit?
> 
> No, since they can't be part of a commit (they don't implement the
> 'call_batch' function).

Ok, good, so they should be safe (but still needs the gfp param to
audit_log_nfcfg() for atomic alloc in that obj reset callback).

> I'm not sure GETOBJ_RESET should be reported in the first place:
> RESET only affects expr internal state, and that state changes all the time
> anyway in response to network traffic.

We report audit lost messages reset as a config change since it affects
the view that an admin has about a system.  An unaccounted for reset
could mislead an administrator into thinking things are alright when
some messages were lost and there was nothing to show for it.  I could
see similar situations with network entity counters.

- 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