From 592c6e9402304c7f6aa5d594dae53c01778eaca7 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <mjg59@srcf.ucam.org>
Date: Fri, 9 Mar 2012 08:39:37 -0500
Subject: [PATCH 06/16] acpi: Limit access to custom_method if securelevel is
set
Patch-mainline: Queued in subsystem maintainer repository
Git-repo: https://github.com/mjg59/linux
Git-commit: 592c6e9402304c7f6aa5d594dae53c01778eaca7
References: fate#320387
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 <mjg59@srcf.ucam.org>
Acked-by: Lee, Chun-Yi <jlee@suse.com>
---
drivers/acpi/custom_method.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/drivers/acpi/custom_method.c
+++ b/drivers/acpi/custom_method.c
@@ -8,6 +8,7 @@
#include <linux/uaccess.h>
#include <linux/debugfs.h>
#include <linux/acpi.h>
+#include <linux/security.h>
#include "internal.h"
@@ -29,6 +30,9 @@ static ssize_t cm_write(struct file *fil
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))