Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933673Ab3CRVif (ORCPT ); Mon, 18 Mar 2013 17:38:35 -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 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-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1307 Lines: 44 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; -- 1.8.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/