[PATCH v2 02/57][X] UBUNTU: SAUCE: (efi-lockdown) x86/mmiotrace: Lock down the testmmiotrace module

[Seth Forshee]

From: David Howells <dhowells at redhat.com>

BugLink: https://bugs.launchpad.net/bugs/1884159

The testmmiotrace module shouldn't be permitted when the kernel is locked
down as it can be used to arbitrarily read and write MMIO space.

Suggested-by: Thomas Gleixner <tglx at linutronix.de>
Signed-off-by: David Howells <dhowells at redhat.com
cc: Thomas Gleixner <tglx at linutronix.de>
cc: Steven Rostedt <rostedt at goodmis.org>
cc: Ingo Molnar <mingo at kernel.org>
cc: "H. Peter Anvin" <hpa at zytor.com>
cc: x86 at kernel.org
(backported from commit 64ce4fc1ef16d4dd818eca47701f803e58444ab2
 git://git.kernel.org/pub/scm/linux/kernel/git/jwboyer/fedora.git)
Signed-off-by: Seth Forshee <seth.forshee at canonical.com>
---
 arch/x86/mm/testmmiotrace.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c
index 38868adf07ea..dd2a4ce7b541 100644
--- a/arch/x86/mm/testmmiotrace.c
+++ b/arch/x86/mm/testmmiotrace.c
@@ -115,6 +115,9 @@ static int __init init(void)
 {
 	unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
 
+	if (secure_modules())
+		return -EPERM;
+
 	if (mmio_address == 0) {
 		pr_err("you have to use the module argument mmio_address.\n");
 		pr_err("DO NOT LOAD THIS MODULE UNLESS YOU REALLY KNOW WHAT YOU ARE DOING!\n");
-- 
2.27.0