linux-kernel - [PATCH 08/10] kexec: Disable at runtime if the kernel enforces module loading restrictions

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Message-Id: <1376928619-3775-8-git-send-email-matthew.garrett@nebula.com>
Date:	Mon, 19 Aug 2013 12:10:17 -0400
From:	Matthew Garrett <matthew.garrett@...ula.com>
To:	linux-kernel@...r.kernel.org
Cc:	linux-efi@...r.kernel.org, jwboyer@...hat.com,
	keescook@...omium.org, Matthew Garrett <matthew.garrett@...ula.com>
Subject: [PATCH 08/10] 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@...ula.com>
---
 kernel/kexec.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/kexec.c b/kernel/kexec.c
index 59f7b55..1a7690f 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -32,6 +32,7 @@
 #include <linux/vmalloc.h>
 #include <linux/swap.h>
 #include <linux/syscore_ops.h>
+#include <linux/module.h>
 
 #include <asm/page.h>
 #include <asm/uaccess.h>
@@ -1645,6 +1646,9 @@ int kernel_kexec(void)
 		goto Unlock;
 	}
 
+	if (secure_modules())
+		return -EPERM;
+
 #ifdef CONFIG_KEXEC_JUMP
 	if (kexec_image->preserve_context) {
 		lock_system_sleep();
-- 
1.8.3.1

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