linux-kernel - Re: [PATCH] per-process securebits

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Date:	Sat, 02 Feb 2008 22:01:51 -0800
From:	"Andrew G. Morgan" <morgan@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Linux Security Modules List 
	<linux-security-module@...r.kernel.org>,
	linux-kernel@...r.kernel.org, "Serge E. Hallyn" <serue@...ibm.com>
Subject: Re: [PATCH] per-process securebits

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Andrew Morton wrote:
| On Fri, 01 Feb 2008 00:11:37 -0800 "Andrew G. Morgan"
<morgan@...nel.org> wrote:
|
|> [This patch represents a no-op unless CONFIG_SECURITY_FILE_CAPABILITIES
|>  is enabled at configure time.]
|
| Patches like this scare the pants off me.

Nice to know I'm not being mediocre! :-D

| I'd have to recommend that distributors not enable this feature (if we
| merge it) until they have 100% convinced themselves that it is 100%
| correct.

FWIW I'm in complete agreement if you are referring to
CONFIG_SECURITY_FILE_CAPABILITIES and not just this patch...

As to the rest, the short version:

* The sendmail thing was a subtle problem trying to map setuid(non-0)
into a capability framework. The long and the short of it was that an
unprivileged user could prevent a privileged application from exercising
all of the privilege it needed and getting root access as a result.

* I'm saying setuid(0) apps will most definitely continue to be
supported by a kernel even with CONFIG_SECURITY_FILE_CAPABILITIES=y. All
the patch does is make it possible for a capable(CAP_SETPCAP) process to
declare itself as the parent of a process tree in which that is not the
case.

Here is the very very long version (which took some time to write, and I
thought was a bit much to spam these lists with):

http://userweb.kernel.org/~morgan/sendmail-capabilities-war-story.html

Cheers

Andrew

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