From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com Date: Tue, 2 Aug 2016 11:52:43 +0200 From: Peter Zijlstra Message-ID: <20160802095243.GD6862@twins.programming.kicks-ass.net> References: <1469630746-32279-1-git-send-email-jeffv@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1469630746-32279-1-git-send-email-jeffv@google.com> Subject: [kernel-hardening] Re: [PATCH 1/2] security, perf: allow further restriction of perf_event_open To: Jeff Vander Stoep Cc: kernel-hardening@lists.openwall.com, mingo@redhat.com, acme@kernel.org, alexander.shishkin@linux.intel.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org List-ID: On Wed, Jul 27, 2016 at 07:45:46AM -0700, Jeff Vander Stoep wrote: > When kernel.perf_event_paranoid is set to 3 (or greater), disallow > all access to performance events by users without CAP_SYS_ADMIN. > > This new level of restriction is intended to reduce the attack > surface of the kernel. Perf is a valuable tool for developers but > is generally unnecessary and unused on production systems. Perf may > open up an attack vector to vulnerable device-specific drivers as > recently demonstrated in CVE-2016-0805, CVE-2016-0819, > CVE-2016-0843, CVE-2016-3768, and CVE-2016-3843. We have bugs we fix them, we don't kill complete infrastructure because of them. > This new level of > restriction allows for a safe default to be set on production systems > while leaving a simple means for developers to grant access [1]. So the problem I have with this is that it will completely inhibit development of things like JITs that self-profile to re-compile frequently used code. I would much rather have an LSM hook where the security stuff can do more fine grained control of things. Allowing some apps perf usage while denying others.