linux-kernel - Re: [PATCH] don't raise all privs on setuid-root file with fE set (v2)

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Message-ID: <20090405035914.GA26896@hallyn.com>
Date:	Sat, 4 Apr 2009 22:59:15 -0500
From:	"Serge E. Hallyn" <serge@...lyn.com>
To:	"Andrew G. Morgan" <morgan@...nel.org>
Cc:	"Serge E. Hallyn" <serue@...ibm.com>,
	linux-security-module@...r.kernel.org,
	lkml <linux-kernel@...r.kernel.org>,
	James Morris <jmorris@...ei.org>,
	Casey Schaufler <casey@...aufler-ca.com>
Subject: Re: [PATCH] don't raise all privs on setuid-root file with fE set
	(v2)

> Serge E. Hallyn wrote:
> > Distributions face a backward compatibility problem with starting to use
> > file capabilities.  For instance, removing setuid root from ping and
> > doing setcap cap_net_raw=pe means that booting with an older kernel
> > or one compiled without file capabilities means ping won't work for
> > non-root users.
> > 
> > In order to replace the setuid root bit on a capability-unaware
> > program, one has to set the effective, or legacy, file capability,
> > which makes the capability effective immediately.  This patch
> > uses the legacy bit as a queue to not automatically add full
> 
> s/queue/cue/

Oops.

(I wonder whether this is worth resending?)

> > privilege to a setuid-root program.
> > 
> > So, with this patch, an ordinary setuid-root program will run with
> > privilege.  But if /bin/ping has both setuid-root and cap_net_raw in
> > fP and fE, then ping (when run by non-root user) will not run
> > with only cap_net_raw.
> 
> Acked-by: Andrew G. Morgan <morgan@...nel.org>

thanks,
-serge
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