From: Matthew Garrett <mjg59@srcf.ucam.org>
Date: Tue, 3 Sep 2013 15:23:29 +0000 (-0400)
Subject: uswsusp: Disable when securelevel is set
X-Git-Tag: archive/raspbian/4.9.82-1+deb9u3+rpi1_jessie~10^2~42
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=349c09774a3803edbc18ec6ff67ca7786b9fe15f;p=linux-4.9.git

uswsusp: Disable when securelevel is set

uswsusp allows a user process to dump and then restore kernel state, which
makes it possible to modify the running kernel. Disable this if securelevel
has been set.

Signed-off-by: Matthew Garrett <mjg59@srcf.ucam.org>

Gbp-Pq: Topic features/all/securelevel
Gbp-Pq: Name uswsusp-disable-when-securelevel-is-set.patch
---

diff --git a/kernel/power/user.c b/kernel/power/user.c
index 35310b627388..d1b274d7c49d 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -24,6 +24,7 @@
 #include <linux/console.h>
 #include <linux/cpu.h>
 #include <linux/freezer.h>
+#include <linux/security.h>
 
 #include <asm/uaccess.h>
 
@@ -52,6 +53,9 @@ static int snapshot_open(struct inode *inode, struct file *filp)
 	if (!hibernation_available())
 		return -EPERM;
 
+	if (get_securelevel() > 0)
+		return -EPERM;
+
 	lock_system_sleep();
 
 	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {