Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754911Ab3IIPw0 (ORCPT ); Mon, 9 Sep 2013 11:52:26 -0400 Received: from cavan.codon.org.uk ([93.93.128.6]:44980 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754582Ab3IIPwN (ORCPT ); Mon, 9 Sep 2013 11:52:13 -0400 From: Matthew Garrett To: linux-kernel@vger.kernel.org Cc: keescook@chromium.org, gregkh@linuxfoundation.org, hpa@zytor.com, linux-efi@vger.kernel.org, jmorris@namei.org, linux-security-module@vger.kernel.org, Matthew Garrett Subject: [PATCH 08/12] kexec: Disable at runtime if securelevel has been set. Date: Mon, 9 Sep 2013 11:49:42 -0400 Message-Id: <1378741786-18430-9-git-send-email-matthew.garrett@nebula.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1378741786-18430-1-git-send-email-matthew.garrett@nebula.com> References: <1378741786-18430-1-git-send-email-matthew.garrett@nebula.com> X-SA-Do-Not-Run: Yes X-SA-Exim-Connect-IP: 2001:470:1f07:1371:5d52:9ee3:3e84:6668 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: 1138 Lines: 39 kexec permits the loading and execution of arbitrary code in ring 0, which permits the modification of the running kernel. Prevent this if securelevel has been set. Signed-off-by: Matthew Garrett --- kernel/kexec.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/kexec.c b/kernel/kexec.c index 59f7b55..98db2a1 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include @@ -942,6 +943,9 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments, if (!capable(CAP_SYS_BOOT)) return -EPERM; + if (get_securelevel() > 0) + return -EPERM; + /* * Verify we have a legal set of flags * This leaves us room for future extensions. -- 1.8.3.1 -- 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/