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Date:   Thu, 20 Jun 2019 18:19:22 -0700
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Subject: [PATCH V33 11/30] uswsusp: Disable when the kernel is locked down
From:   Matthew Garrett <matthewgarrett@google.com>
To:     jmorris@namei.org
Cc:     linux-security@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-api@vger.kernel.org, Matthew Garrett <mjg59@srcf.ucam.org>,
        David Howells <dhowells@redhat.com>,
        Matthew Garrett <mjg59@google.com>, linux-pm@vger.kernel.org,
        pavel@ucw.cz, rjw@rjwysocki.net
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Sender: linux-kernel-owner@vger.kernel.org
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From: Matthew Garrett <mjg59@srcf.ucam.org>

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: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
cc: linux-pm@vger.kernel.org
Cc: pavel@ucw.cz
Cc: rjw@rjwysocki.net
---
 kernel/power/user.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/power/user.c b/kernel/power/user.c
index 2d8b60a3c86b..8a8d7f1c8fbb 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 <linux/uaccess.h>
 
@@ -52,6 +53,9 @@ static int snapshot_open(struct inode *inode, struct file *filp)
 	if (!hibernation_available())
 		return -EPERM;
 
+	if (security_is_locked_down(LOCKDOWN_HIBERNATION))
+		return -EPERM;
+
 	lock_system_sleep();
 
 	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
-- 
2.22.0.410.gd8fdbe21b5-goog