kernel/kexec-Disable-at-runtime-if-the-kernel-enforces-modu.patch

From 85968a9f0b3f05c56d4ac4002748f3412a9baab0 Mon Sep 17 00:00:00 2001
From: Matthew Garrett <matthew.garrett@nebula.com>
Date: Fri, 9 Aug 2013 03:33:56 -0400
Subject: [PATCH 08/20] kexec: Disable at runtime if the kernel enforces module
 loading restrictions

kexec permits the loading and execution of arbitrary code in ring 0, which
is something that module signing enforcement is meant to prevent. It makes
sense to disable kexec in this situation.

Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
---
 kernel/kexec.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/kexec.c b/kernel/kexec.c
index 980936a90ee6..fce28bf7d5d7 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -12,6 +12,7 @@
 #include <linux/mm.h>
 #include <linux/file.h>
 #include <linux/kexec.h>
+#include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/list.h>
 #include <linux/syscalls.h>
@@ -194,6 +195,13 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
 		return -EPERM;
 
 	/*
+	 * kexec can be used to circumvent module loading restrictions, so
+	 * prevent loading in that case
+	 */
+	if (secure_modules())
+		return -EPERM;
+
+	/*
 	 * Verify we have a legal set of flags
 	 * This leaves us room for future extensions.
 	 */
-- 
2.9.3