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

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Date:	Sat, 04 Apr 2009 11:04:10 -0700
From:	"Andrew G. Morgan" <morgan@...nel.org>
To:	"Serge E. Hallyn" <serue@...ibm.com>
CC:	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)

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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/

> 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>

Cheers

Andrew
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