linux-kernel - Re: [PATCH 2/2] groups: Allow unprivileged processes to use setgroups to drop groups

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20141116034005.GC5507@thunk.org>
Date:	Sat, 15 Nov 2014 22:40:06 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	Josh Triplett <josh@...htriplett.org>
Cc:	Andy Lutomirski <luto@...capital.net>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kees Cook <keescook@...omium.org>,
	Michael Kerrisk-manpages <mtk.manpages@...il.com>,
	Linux API <linux-api@...r.kernel.org>,
	linux-man <linux-man@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] groups: Allow unprivileged processes to use
 setgroups to drop groups

On Sat, Nov 15, 2014 at 06:35:05PM -0800, Josh Triplett wrote:
> >So arbitrarily anyone to drop groups from their supplemental group
> >list will result in a change from both existing practice and legacy
> >Unix systems, and it could potentially lead to a security exposure.
> 
> As Andy pointed out, you can already do that with a user namespace,
> for any case not involving a setuid or setgid (or otherwise
> privilege-gaining) program.  And requiring no_new_privs handles
> that.

Well, it's no worse than what we can do already with the user
namespace, yes.  I'm still worried it's going to come as a surprise
for some configurations because it's a change from what was allowed
historically.  Then again, pretty much all of the tripwire and rootkit
scanners won't notice a "setuid" program that uses capabilities
instead of the traditional setuid bit, and most sysadmins won't think
to check for an executable with a forced capability mask, so this
isn't exactly a new problem....

							- Ted
							
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/