linux-kernel - Re: [PATCH 2/2] file capabilities: turn on by default

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Message-ID: <20080922195647.GA25682@us.ibm.com>
Date:	Mon, 22 Sep 2008 14:56:47 -0500
From:	"Serge E. Hallyn" <serue@...ibm.com>
To:	Randy Dunlap <randy.dunlap@...cle.com>
Cc:	lkml <linux-kernel@...r.kernel.org>,
	linux-security-module@...r.kernel.org,
	James Morris <jmorris@...hat.com>,
	Andrew Morgan <morgan@...nel.org>,
	Andreas Gruenbacher <agruen@...e.de>,
	Andrew Morton <akpm@...l.org>,
	Chris Wright <chrisw@...s-sol.org>
Subject: Re: [PATCH 2/2] file capabilities: turn on by default

Quoting Randy Dunlap (randy.dunlap@...cle.com):
> On Mon, 22 Sep 2008 13:49:01 -0500 Serge E. Hallyn wrote:
> 
> > 
> > Now that file capabilities can be turned off at boot, go ahead
> > and compile them into the kernel by default by making
> > CONFIG_SECURITY_FILE_CAPABILITIES=y the default.
> 
> Hi,
> 
> How much code does this add to everyone's kernel?

Here are the sizes I get with Linus' plain tree and patched
with both of these patches:

master  with file capabilities: 6241626
master  w/o  file capabilities: 6241595

patched with file capabilities: 6241782
patched w/o  file capabilities: 6241595

So actually I don't like the added size.

> > Note that the boot flag no_file_caps must be specified to turn
> > file capabilities off, as by default they are on.  So the
> > default behavior is in fact changed.
> 
> If most people want this enable, using 'no_file_caps' makes
> some sense.  OTOH, if most people don't want/use it, then
> having a 'file_caps_on' option would make more sense.
> 
> Do you have any (unbiased :) ideas about this?

I'll sit this one out I guess :)

> Thanks.
> 
> > Signed-off-by: Serge Hallyn <serue@...ibm.com>
> > Acked-by: Andrew G. Morgan <morgan@...nel.org>
> > ---
> >  security/Kconfig |    7 +++++--
> >  1 files changed, 5 insertions(+), 2 deletions(-)
> > 
> > diff --git a/security/Kconfig b/security/Kconfig
> > index 5592939..6fbb233 100644
> > --- a/security/Kconfig
> > +++ b/security/Kconfig
> > @@ -75,12 +75,15 @@ config SECURITY_NETWORK_XFRM
> >  
> >  config SECURITY_FILE_CAPABILITIES
> >  	bool "File POSIX Capabilities"
> > -	default n
> > +	default y
> >  	help
> >  	  This enables filesystem capabilities, allowing you to give
> >  	  binaries a subset of root's powers without using setuid 0.
> >  
> > -	  If in doubt, answer N.
> > +	  You can still boot with the no_file_caps option to disable
> > +	  file capabilities.
> > +
> > +	  If in doubt, answer Y.
> >  
> >  config SECURITY_ROOTPLUG
> >  	bool "Root Plug Support"
> 
> 
> ---
> ~Randy
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