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Message-ID: <4B0B0DDB.4070504@oracle.com>
Date: Mon, 23 Nov 2009 14:34:03 -0800
From: Randy Dunlap <randy.dunlap@...cle.com>
To: "Serge E. Hallyn" <serue@...ibm.com>
CC: James Morris <jmorris@...ei.org>,
lkml <linux-kernel@...r.kernel.org>,
"Andrew G. Morgan" <morgan@...nel.org>,
Steve Grubb <sgrubb@...hat.com>,
linux-security-module@...r.kernel.org,
Kees Cook <kees.cook@...onical.com>,
Andreas Gruenbacher <agruen@...e.de>,
Michael Kerrisk <mtk.manpages@...il.com>,
George Wilson <gcwilson@...ibm.com>,
KaiGai Kohei <kaigai@...gai.gr.jp>
Subject: Re: [PATCH] remove CONFIG_SECURITY_FILE_CAPABILITIES compile option
Serge E. Hallyn wrote:
> As far as I know, all distros currently ship kernels with default
> CONFIG_SECURITY_FILE_CAPABILITIES=y. Since having the option on
> leaves a 'no_file_caps' option to boot without file capabilities,
> the main reason to keep the option is that turning it off saves
> you (on my s390x partition) 5k. In particular, vmlinux sizes
> came to:
>
> without patch fscaps=n: 53598392
> without patch fscaps=y: 53603406
> with this patch applied: 53603342
>
> with the security-next tree.
>
> Against this we must weigh the fact that there is no simple way for
> userspace to figure out whether file capabilities are supported,
> while things like per-process securebits, capability bounding
> sets, and adding bits to pI if CAP_SETPCAP is in pE are not supported
> with SECURITY_FILE_CAPABILITIES=n, leaving a bit of a problem for
> applications wanting to know whether they can use them and/or why
> something failed.
>
> It also adds another subtly different set of semantics which we must
> maintain at the risk of severe security regressions.
Hi,
This is or is not the same security option that is referred to in
(new:) http://bugzilla.kernel.org/show_bug.cgi?id=14675 ?
> So this patch removes the SECURITY_FILE_CAPABILITIES compile
> option. It drops the kernel size by about 50k over the stock
> SECURITY_FILE_CAPABILITIES=y kernel, by removing the
> cap_limit_ptraced_target() function.
>
> Changelog:
> Nov 20: remove cap_limit_ptraced_target() as it's logic
> was ifndef'ed.
>
> Signed-off-by: Serge E. Hallyn <serue@...ibm.com>
> Acked-by: Andrew G. Morgan" <morgan@...nel.org>
> ---
> include/linux/capability.h | 2 -
> include/linux/init_task.h | 4 --
> kernel/capability.c | 2 -
> security/Kconfig | 9 -----
> security/commoncap.c | 72 +------------------------------------------
> 5 files changed, 2 insertions(+), 87 deletions(-)
--
~Randy
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