linux-kernel - Re: [PATCH ghak90 V7 20/21] audit: add capcontid to set contid outside init_user

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Message-ID: <CAHC9VhRdNXsY4neJpSoNyJoAVEoiEc2oW5kSscF99tjmoQAxFA@mail.gmail.com>
Date:   Mon, 21 Oct 2019 17:43:21 -0400
From:   Paul Moore <paul@...l-moore.com>
To:     Richard Guy Briggs <rgb@...hat.com>
Cc:     containers@...ts.linux-foundation.org, linux-api@...r.kernel.org,
        Linux-Audit Mailing List <linux-audit@...hat.com>,
        linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        netdev@...r.kernel.org, netfilter-devel@...r.kernel.org,
        sgrubb@...hat.com, omosnace@...hat.com, dhowells@...hat.com,
        simo@...hat.com, Eric Paris <eparis@...isplace.org>,
        Serge Hallyn <serge@...lyn.com>, ebiederm@...ssion.com,
        nhorman@...driver.com, Dan Walsh <dwalsh@...hat.com>,
        mpatel@...hat.com
Subject: Re: [PATCH ghak90 V7 20/21] audit: add capcontid to set contid
 outside init_user_ns

On Mon, Oct 21, 2019 at 5:38 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> On 2019-10-21 15:53, Paul Moore wrote:
> > On Fri, Oct 18, 2019 at 9:39 PM Richard Guy Briggs <rgb@...hat.com> wrote:
> > > On 2019-09-18 21:22, Richard Guy Briggs wrote:
> > > > Provide a mechanism similar to CAP_AUDIT_CONTROL to explicitly give a
> > > > process in a non-init user namespace the capability to set audit
> > > > container identifiers.
> > > >
> > > > Use audit netlink message types AUDIT_GET_CAPCONTID 1027 and
> > > > AUDIT_SET_CAPCONTID 1028.  The message format includes the data
> > > > structure:
> > > > struct audit_capcontid_status {
> > > >         pid_t   pid;
> > > >         u32     enable;
> > > > };
> > >
> > > Paul, can I get a review of the general idea here to see if you're ok
> > > with this way of effectively extending CAP_AUDIT_CONTROL for the sake of
> > > setting contid from beyond the init user namespace where capable() can't
> > > reach and ns_capable() is meaningless for these purposes?
> >
> > I think my previous comment about having both the procfs and netlink
> > interfaces apply here.  I don't see why we need two different APIs at
> > the start; explain to me why procfs isn't sufficient.  If the argument
> > is simply the desire to avoid mounting procfs in the container, how
> > many container orchestrators can function today without a valid /proc?
>
> Ok, sorry, I meant to address that question from a previous patch
> comment at the same time.
>
> It was raised by Eric Biederman that the proc filesystem interface for
> audit had its limitations and he had suggested an audit netlink
> interface made more sense.

I'm sure you've got it handy, so I'm going to be lazy and ask: archive
pointer to Eric's comments?  Just a heads-up, I'm really *not* a fan
of using the netlink interface for this, so unless Eric presents a
super compelling reason for why we shouldn't use procfs I'm inclined
to stick with /proc.

> The intent was to switch to the audit netlink interface for contid,
> capcontid and to add the audit netlink interface for loginuid and
> sessionid while deprecating the proc interface for loginuid and
> sessionid.  This was alluded to in the cover letter, but not very clear,
> I'm afraid.  I have patches to remove the contid and loginuid/sessionid
> interfaces in another tree which is why I had forgotten to outline that
> plan more explicitly in the cover letter.

-- 
paul moore
www.paul-moore.com