linux-kernel - Re: [PATCH ghak124 v2] audit: log nftables configuration change events

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Message-ID: <20200602113417.kfrmwm57snkaiv3y@madcap2.tricolour.ca>
Date:   Tue, 2 Jun 2020 07:34:17 -0400
From:   Richard Guy Briggs <rgb@...hat.com>
To:     Paul Moore <paul@...l-moore.com>
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 v2] audit: log nftables configuration change
 events

On 2020-06-01 20:12, Paul Moore wrote:
> On Mon, Jun 1, 2020 at 6:58 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> > On 2020-06-01 12:10, Paul Moore wrote:
> > > On Thu, May 28, 2020 at 9:44 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> 
> ...
> 
> > > > diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> > > > index 4471393da6d8..7a386eca6e04 100644
> > > > --- a/net/netfilter/nf_tables_api.c
> > > > +++ b/net/netfilter/nf_tables_api.c
> > > > @@ -12,6 +12,7 @@
> > > >  #include <linux/netlink.h>
> > > >  #include <linux/vmalloc.h>
> > > >  #include <linux/rhashtable.h>
> > > > +#include <linux/audit.h>
> > > >  #include <linux/netfilter.h>
> > > >  #include <linux/netfilter/nfnetlink.h>
> > > >  #include <linux/netfilter/nf_tables.h>
> > > > @@ -693,6 +694,14 @@ static void nf_tables_table_notify(const struct nft_ctx *ctx, int event)
> > > >  {
> > > >         struct sk_buff *skb;
> > > >         int err;
> > > > +       char *buf = kasprintf(GFP_KERNEL, "%s:%llu;?:0",
> > > > +                             ctx->table->name, ctx->table->handle);
> > > > +
> > > > +       audit_log_nfcfg(buf,
> > > > +                       ctx->family,
> > > > +                       ctx->table->use,
> > > > +                       audit_nftcfgs[event].op);
> > >
> > > As an example, the below would work, yes?
> > >
> > > audit_log_nfcfg(...,
> > >  (event == NFT_MSG_NEWTABLE ?
> > >   AUDIT_NFT_OP_TABLE_REGISTER :
> > >   AUDIT_NFT_OP_TABLE_UNREGISTER)
> >
> > Ok, I see what you are getting at now...  Yes, it could be done this
> > way, but it seems noisier to me.
> 
> I'll admit it is not as clean, but it doesn't hide the mapping between
> the netfilter operation and the audit operation which hopefully makes
> it clear to those modifying the netfilter/nf_tables/etc. code that
> there is an audit impact.  I'm basically trying to make sure the code
> is as robust as possible in the face of subsystem changes beyond the
> audit subsystem.

Yup, I agree, a compile time check to make sure they aren't out of sync.

> paul moore

- 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