From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754198AbbCIVUs (ORCPT ); Mon, 9 Mar 2015 17:20:48 -0400 Received: from mx2.parallels.com ([199.115.105.18]:58772 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753701AbbCIVUn (ORCPT ); Mon, 9 Mar 2015 17:20:43 -0400 Message-ID: <54FE0EA0.7030002@parallels.com> Date: Tue, 10 Mar 2015 00:20:32 +0300 From: Pavel Emelyanov User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: "Kirill A. Shutemov" , , , Andrew Morton , Linus Torvalds CC: "Kirill A. Shutemov" , "Konstantin Khlebnikov" , Mark Seaborn , Andy Lutomirski Subject: Re: [RFC, PATCH] pagemap: do not leak physical addresses to non-privileged userspace References: <1425935472-17949-1-git-send-email-kirill@shutemov.name> In-Reply-To: <1425935472-17949-1-git-send-email-kirill@shutemov.name> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Originating-IP: [40.139.179.11] X-ClientProxiedBy: US-EXCH.sw.swsoft.com (10.255.249.47) To US-EXCH.sw.swsoft.com (10.255.249.47) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/10/2015 12:11 AM, Kirill A. Shutemov wrote: > From: "Kirill A. Shutemov" > > As pointed by recent post[1] on exploiting DRAM physical imperfection, > /proc/PID/pagemap exposes sensitive information which can be used to do > attacks. > > This is RFC patch which disallow anybody without CAP_SYS_ADMIN to read > the pagemap. > > Any comments? If I'm not mistaken, the pagemap file is used by some userspace that does working-set size analysis. But this thing only needs the flags (referenced bit) from the PTE-s. Maybe it would be better not to lock this file completely, but instead report the PFN part as zero? Other than this, I don't mind :) Although we use this heavily in CRIU we anyway work only with the CAP_SYS_ADMIN, so adding the new one doesn't hurt. Thanks, Pavel > [1] http://googleprojectzero.blogspot.com/2015/03/exploiting-dram-rowhammer-bug-to-gain.html > > Signed-off-by: Kirill A. Shutemov > Cc: Pavel Emelyanov > Cc: Konstantin Khlebnikov > Cc: Andrew Morton > Cc: Linus Torvalds > Cc: Mark Seaborn > Cc: Andy Lutomirski > --- > fs/proc/task_mmu.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > index 246eae84b13b..b72b36e64286 100644 > --- a/fs/proc/task_mmu.c > +++ b/fs/proc/task_mmu.c > @@ -1322,6 +1322,9 @@ out: > > static int pagemap_open(struct inode *inode, struct file *file) > { > + /* do not disclose physical addresses: attack vector */ > + if (!capable(CAP_SYS_ADMIN)) > + return -EPERM; > pr_warn_once("Bits 55-60 of /proc/PID/pagemap entries are about " > "to stop being page-shift some time soon. See the " > "linux/Documentation/vm/pagemap.txt for details.\n"); >