Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754735Ab3IIPwT (ORCPT ); Mon, 9 Sep 2013 11:52:19 -0400 Received: from cavan.codon.org.uk ([93.93.128.6]:44968 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754573Ab3IIPwL (ORCPT ); Mon, 9 Sep 2013 11:52:11 -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 06/12] acpi: Limit access to custom_method if securelevel is set Date: Mon, 9 Sep 2013 11:49:40 -0400 Message-Id: <1378741786-18430-7-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: 1254 Lines: 39 custom_method effectively allows arbitrary access to system memory, making it possible for an attacker to modify the kernel at runtime. Prevent this if securelevel has been set. Signed-off-by: Matthew Garrett --- drivers/acpi/custom_method.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c index 12b62f2..8b881db 100644 --- a/drivers/acpi/custom_method.c +++ b/drivers/acpi/custom_method.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include "internal.h" @@ -29,6 +30,9 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf, struct acpi_table_header table; acpi_status status; + if (get_securelevel() > 0) + return -EPERM; + if (!(*ppos)) { /* parse the table header to get the table length */ if (count <= sizeof(struct acpi_table_header)) -- 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/