linux-kernel - Re: [RFC 2/5 v4] procfs: add hidepid= and gid= mount options

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: <20110620170600.GA25601@albatros>
Date:	Mon, 20 Jun 2011 21:06:01 +0400
From:	Vasiliy Kulikov <segoon@...nwall.com>
To:	James Morris <jmorris@...ei.org>
Cc:	kernel-hardening@...ts.openwall.com, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: Re: [RFC 2/5 v4] procfs: add hidepid= and gid= mount options

(cc'ed Eric)

On Mon, Jun 20, 2011 at 20:43 +1000, James Morris wrote:
> > > > hidepid=1 means users may not access any /proc/<pid>/ directories, but their
> > > > own.  Sensitive files like cmdline, io, sched*, status, wchan are now
> > > > protected against other users.  As permission checking done in
> > > > proc_pid_permission() and files' permissions are left untouched,
> > > > programs expecting specific files' permissions are not confused.
> > > 
> > > IMHO such programs are beyond broken and have voided their kernel 
> > > warranty.
> > 
> > Policykit, Debian's start-stop-daemon, util-linux use /proc/PID's uid.
> > procps use both /proc/PID's uid and gid.  Are all of them totally broken?
> 
> If they depend on specific permissions, yes.

Could you please then clarify why does this patch changes
pid_revalidate() behaviour:

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=99f895518368252ba862cc15ce4eb98ebbe1bec6

It changes files permissions to allow userspace apps to quickly stat
files, not looking into /proc/PID/status.  So, uid and gid are explicit
ABI.  Breaking procfs uid/gid attributes would break these apps.

Or am I missing something?


Thanks,

-- 
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
--
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/