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

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Date:   Fri, 1 Nov 2019 12:02:25 +1100
From:   Duncan Roe <duncan_roe@...usnet.com.au>
To:     Steve Grubb <sgrubb@...hat.com>
Cc:     Richard Guy Briggs <rgb@...hat.com>,
        Paul Moore <paul@...l-moore.com>,
        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,
        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 Thu, Oct 31, 2019 at 10:50:57AM -0400, Steve Grubb wrote:
> Hello,
>
> TLDR;  I see a lot of benefit to switching away from procfs for setting auid &
> sessionid.
>
> On Wednesday, October 30, 2019 6:03:20 PM EDT Richard Guy Briggs wrote:
> > > Also, for the record, removing the audit loginuid from procfs is not
> > > something to take lightly, if at all; like it or not, it's part of the
> > > kernel API.
>
> It can also be used by tools to iterate processes related to one user or
> session. I use this in my Intrusion Prevention System which will land in
> audit user space at some point in the future.
>
>
> > Oh, I'm quite aware of how important this change is and it was discussed
> > with Steve Grubb who saw the concern and value of considering such a
> > disruptive change.
>
> Actually, I advocated for syscall. I think the gist of Eric's idea was that /
> proc is the intersection of many nasty problems. By relying on it, you can't
> simplify the API to reduce the complexity. Almost no program actually needs
                                             ^^^^^^ ^^ ^^^^^^^ ^^^^^^^^ ^^^^^
> access to /proc. ps does. But almost everything else is happy without it. For
> ^^^^^^ ^^ ^^^^^^ ^^ ^^^^^

Eh?? *top* needs /proc/ps, as do most of the programs in package procps-ng.
Then there's lsof, pgrep (which doesn't fail but can't find anything) and even
lilo (for Slackware ;)

> example, when you setup chroot jails, you may have to add /dev/random or /
> dev/null, but almost never /proc. What does force you to add /proc is any
> entry point daemon like sshd because it needs to set the loginuid. If we
> switch away from /proc, then sshd or crond will no longer /require/ procfs to
> be available which again simplifies the system design.
>
>
> > Removing proc support for auid/ses would be a
> > long-term deprecation if accepted.
>
> It might need to just be turned into readonly for a while. But then again,
> perhaps auid and session should be part of /proc/<pid>/status? Maybe this can
> be done independently and ahead of the container work so there is a migration
> path for things that read auid or session. TBH, maybe this should have been
> done from the beginning.
>
> -Steve
>
Cheers ... Duncan.