From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com Sender: Vasiliy Kulikov Date: Mon, 20 Jun 2011 21:06:01 +0400 From: Vasiliy Kulikov Message-ID: <20110620170600.GA25601@albatros> References: <20110620103917.GA5230@albatros> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: [kernel-hardening] Re: [RFC 2/5 v4] procfs: add hidepid= and gid= mount options To: James Morris Cc: kernel-hardening@lists.openwall.com, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, "Eric W. Biederman" List-ID: (cc'ed Eric) On Mon, Jun 20, 2011 at 20:43 +1000, James Morris wrote: > > > > hidepid=1 means users may not access any /proc// 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