From: Matthew Garrett <mjg59@srcf.ucam.org>
Date: Wed, 8 Nov 2017 15:11:33 +0000 (+0000)
Subject: uswsusp: Disable when the kernel is locked down
X-Git-Tag: archive/raspbian/4.16.16-2+rpi1^2~38
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=7a8c347eb90c9613f9053e7d808c7587aa65705a;p=linux.git

uswsusp: Disable when the kernel is locked down

uswsusp allows a user process to dump and then restore kernel state, which
makes it possible to modify the running kernel.  Disable this if the kernel
is locked down.

Signed-off-by: Matthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com>
Reviewed-by: James Morris <james.l.morris@oracle.com>
cc: linux-pm@vger.kernel.org

Gbp-Pq: Topic features/all/lockdown
Gbp-Pq: Name 0010-uswsusp-Disable-when-the-kernel-is-locked-down.patch
---

diff --git a/kernel/power/user.c b/kernel/power/user.c
index 22df9f7ff67..678ade9decf 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -52,6 +52,9 @@ static int snapshot_open(struct inode *inode, struct file *filp)
 	if (!hibernation_available())
 		return -EPERM;
 
+	if (kernel_is_locked_down("/dev/snapshot"))
+		return -EPERM;
+
 	lock_system_sleep();
 
 	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {