From b0d3311bdba8183d94670473d980bd49a28f974d 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] 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 2bee072268d9..891477dbfee0 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -36,6 +36,7 @@
#include <linux/syscore_ops.h>
#include <linux/compiler.h>
#include <linux/hugetlb.h>
+#include <linux/module.h>
#include <asm/page.h>
#include <asm/uaccess.h>
@@ -1251,6 +1252,13 @@ 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.
*/
--
1.9.3