linux-kernel - [PATCH 09/27] uswsusp: Disable when the kernel is locked down

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Message-ID: <150842470227.7923.15293760935442172683.stgit@warthog.procyon.org.uk>
Date:   Thu, 19 Oct 2017 15:51:42 +0100
From:   David Howells <dhowells@...hat.com>
To:     linux-security-module@...r.kernel.org
Cc:     gnomes@...rguk.ukuu.org.uk, linux-efi@...r.kernel.org,
        matthew.garrett@...ula.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, dhowells@...hat.com,
        jforbes@...hat.com
Subject: [PATCH 09/27] uswsusp: Disable when the kernel is locked down

From: Matthew Garrett <mjg59@...f.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: Matthew Garrett <mjg59@...f.ucam.org>
Signed-off-by: David Howells <dhowells@...hat.com>
cc: linux-pm@...r.kernel.org
---

 kernel/power/user.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/power/user.c b/kernel/power/user.c
index 22df9f7ff672..678ade9decfe 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)) {