From: Matthew Garrett <matthew.garrett@nebula.com>
Date: Mon, 9 Sep 2013 22:49:40 +0000 (-0700)
Subject: acpi: Limit access to custom_method if securelevel is set
X-Git-Tag: v4.1.12-92~310^2~9
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=3c7af10dc5281fbef68a2febb4af5e7ff88fd816;p=users%2Fjedix%2Flinux-maple.git

acpi: Limit access to custom_method if securelevel is set

Orabug: 21539498

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@nebula.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
---

diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c
index c68e72414a67a..359f45d54543a 100644
--- 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 *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))