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Date: Mon, 9 Sep 2013 11:49:40 -0400
From: Matthew Garrett <matthew.garrett@...ula.com>
To: linux-kernel@...r.kernel.org
Cc: keescook@...omium.org, gregkh@...uxfoundation.org, hpa@...or.com,
linux-efi@...r.kernel.org, jmorris@...ei.org,
linux-security-module@...r.kernel.org,
Matthew Garrett <matthew.garrett@...ula.com>
Subject: [PATCH 06/12] acpi: Limit access to custom_method if securelevel is set
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 <matthew.garrett@...ula.com>
---
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 <linux/kernel.h>
#include <linux/uaccess.h>
#include <linux/debugfs.h>
+#include <linux/security.h>
#include <acpi/acpi_drivers.h>
#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
--
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