From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754113AbaI2RiO (ORCPT ); Mon, 29 Sep 2014 13:38:14 -0400 Received: from omr1.cc.vt.edu ([198.82.141.52]:59049 "EHLO omr1.cc.vt.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753249AbaI2RiM (ORCPT ); Mon, 29 Sep 2014 13:38:12 -0400 X-Mailer: exmh version 2.8.0 04/21/2012 with nmh-1.6+dev To: Andy Lutomirski Cc: Peter Zijlstra , Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo , "linux-kernel@vger.kernel.org" Subject: Re: Tightening up rdpmc permissions? In-Reply-To: Your message of "Mon, 29 Sep 2014 09:39:16 -0700." From: Valdis.Kletnieks@vt.edu References: Mime-Version: 1.0 Content-Type: multipart/signed; boundary="==_Exmh_1412012181_2318P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit Date: Mon, 29 Sep 2014 13:36:22 -0400 Message-ID: <9930.1412012182@turing-police.cc.vt.edu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --==_Exmh_1412012181_2318P Content-Type: text/plain; charset=us-ascii On Mon, 29 Sep 2014 09:39:16 -0700, Andy Lutomirski said: > Would it make sense to restrict rdpmc to tasks that are in mms that > have a perf_event mapping? After all, unless I misunderstand > something, user code can't reliably use rdpmc unless they've mapped a > perf_event object to check the rdpmc bit and figure out what ecx value > to use. Wouldn't that be trivially easy for an attacker to bypass? Just map a dummy perf_event object and then go to town? --==_Exmh_1412012181_2318P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 Comment: Exmh version 2.5 07/13/2001 iQIVAwUBVCmYlQdmEQWDXROgAQJyFA//enFNilqa4+HBkAK48ZG9i2YmyojtcGTL AXAuT3XHq979DYzlZcxnaKnWD4DV87fUZgig10Sk5ziAecLhzI7wRcSLpbje/aBN mPwyzD4Qt8DH2kw+4rkNliZQI163fcpGHhxMArHgs2U95PKkeP+1ZTdNqsiTamTp ziPf1wcdIxZqc87G/KwEgYALbjVb5Nzdj061FxFDbBOyEMLWmSQvLWhPMFNKljpp m1IB7udKHr1Z+suOrhwPkKLNBppEiE8FSjuxEJpgJKn1+bE037dB3kRi+P+/CKBS xUoOsO31d4Mp446tDlqBbZkp4aIR3lnTU7WcgYYvYmC2nF42y+5E5P0W558yXnJ1 gEF4m90o392/9EnVB3InTC0c6KxKHt1zNEoJIIB/TWSHXTxpzKVt+JkblK80T7WH JIDQTL2Xn21lMX7fGeEBm9wlvHKU29zAT/A8ISzPNUACtxKAyzcQJ2YIOjYZSSON uRUbufgIZdMF1uukp13g8XRedsfQ8aPc04B2PCe1WZoeRZNW/b93thdDeZPKU7ZB Svlip91Rd3AOMq1Ts0naMQfc4au44hnsHSap29iFRSNCGDJ0RAzC3sUjzoVSZw2O FHam8IW2tlphvf8fb6dkrlRWeQGMSOUFBoyENwCPhcTTQRiK093cj8kfWJJ48/1f oQmWlIkSfYs= =zAL1 -----END PGP SIGNATURE----- --==_Exmh_1412012181_2318P--