From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com From: Dave Hansen In-Reply-To: <20110914131630.GA7001@albatros> References: <20110910164001.GA2342@albatros> <20110910164134.GA2442@albatros> <20110914131630.GA7001@albatros> Content-Type: text/plain; charset="UTF-8" Date: Wed, 14 Sep 2011 08:18:25 -0700 Message-ID: <1316013505.4478.50.camel@nimitz> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [kernel-hardening] Re: [RFC PATCH 2/2] mm: restrict access to /proc/slabinfo To: Vasiliy Kulikov Cc: kernel-hardening@lists.openwall.com, Andrew Morton , Cyrill Gorcunov , Al Viro , Christoph Lameter , Pekka Enberg , Matt Mackall , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dan Rosenberg , Theodore Tso , Alan Cox , Jesper Juhl , Linus Torvalds List-ID: On Wed, 2011-09-14 at 17:16 +0400, Vasiliy Kulikov wrote: > > World readable slabinfo simplifies kernel developers' job of debugging > > kernel bugs (e.g. memleaks), but I believe it does more harm than > > benefits. For most users 0444 slabinfo is an unreasonable attack vector. > > Please tell if anybody has complains about the restriction - whether it > forces someone besides kernel developers to do "chmod/chgrp". But if > someone want to debug the kernel, it shouldn't significantly influence > on common users, especially it shouldn't create security issues. Ubuntu ships today with a /etc/init/mounted-proc.conf that does: chmod 0400 "${MOUNTPOINT}"/slabinfo After cursing Kees's name a few times, I commented it out and it hasn't bothered me again. I expect that the folks that really care about this (and their distros) will probably have a similar mechanism. I guess the sword cuts both ways in this case: it obviously _works_ to have the distros do it, but it was a one-time inconvenience for me to override that. In other words, I dunno. If we do this in the kernel, can we at least do something like CONFIG_INSECURE to both track these kinds of things and make it easy to get them out of a developer's way? -- Dave