From patchwork Mon Mar 18 21:32:32 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Garrett X-Patchwork-Id: 2296451 X-Patchwork-Delegate: bhelgaas@google.com Return-Path: X-Original-To: patchwork-linux-pci@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id AF67FE00E6 for ; Mon, 18 Mar 2013 21:38:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933253Ab3CRVie (ORCPT ); Mon, 18 Mar 2013 17:38:34 -0400 Received: from cavan.codon.org.uk ([93.93.128.6]:36047 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933659Ab3CRVic (ORCPT ); Mon, 18 Mar 2013 17:38:32 -0400 Received: from [2001:470:1f07:1371:e0f4:3a1:9c35:d688] (helo=x230.mview.int.nebula.com) by cavan.codon.org.uk with esmtpsa (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.72) (envelope-from ) id 1UHhfx-0006Ez-48; Mon, 18 Mar 2013 21:33:01 +0000 From: Matthew Garrett To: linux-kernel@vger.kernel.org Cc: linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, Kees Cook , Matthew Garrett Subject: [PATCH 11/12] x86: Require CAP_COMPROMISE_KERNEL for MSR writing Date: Mon, 18 Mar 2013 17:32:32 -0400 Message-Id: <1363642353-30749-11-git-send-email-matthew.garrett@nebula.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1363642353-30749-1-git-send-email-matthew.garrett@nebula.com> References: <1363642353-30749-1-git-send-email-matthew.garrett@nebula.com> X-SA-Do-Not-Run: Yes X-SA-Exim-Connect-IP: 2001:470:1f07:1371:e0f4:3a1:9c35:d688 X-SA-Exim-Mail-From: matthew.garrett@nebula.com X-SA-Exim-Scanned: No (on cavan.codon.org.uk); SAEximRunCond expanded to false Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Kees Cook Writing to MSRs should not be allowed unless CAP_COMPROMISE_KERNEL is set since it could lead to execution of arbitrary code in kernel mode. Signed-off-by: Kees Cook Signed-off-by: Matthew Garrett --- arch/x86/kernel/msr.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c index ce13049..fa4dc6c 100644 --- a/arch/x86/kernel/msr.c +++ b/arch/x86/kernel/msr.c @@ -103,6 +103,9 @@ static ssize_t msr_write(struct file *file, const char __user *buf, int err = 0; ssize_t bytes = 0; + if (!capable(CAP_COMPROMISE_KERNEL)) + return -EPERM; + if (count % 8) return -EINVAL; /* Invalid chunk size */ @@ -150,6 +153,10 @@ static long msr_ioctl(struct file *file, unsigned int ioc, unsigned long arg) err = -EBADF; break; } + if (!capable(CAP_COMPROMISE_KERNEL)) { + err = -EPERM; + break; + } if (copy_from_user(®s, uregs, sizeof regs)) { err = -EFAULT; break;