From: David Howells <dhowells@redhat.com>
Date: Wed, 8 Nov 2017 15:11:36 +0000 (+0000)
Subject: x86/mmiotrace: Lock down the testmmiotrace module
X-Git-Tag: archive/raspbian/4.18.10-2+rpi1^2~34
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=6e73e8aaeb091e4b60aeaceb6416fc09df0066cd;p=linux.git

x86/mmiotrace: Lock down the testmmiotrace module

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@linutronix.de>
Signed-off-by: David Howells <dhowells@redhat.com
cc: Thomas Gleixner <tglx@linutronix.de>
cc: Steven Rostedt <rostedt@goodmis.org>
cc: Ingo Molnar <mingo@kernel.org>
cc: "H. Peter Anvin" <hpa@zytor.com>
cc: x86@kernel.org

Gbp-Pq: Topic features/all/lockdown
Gbp-Pq: Name 0023-x86-mmiotrace-Lock-down-the-testmmiotrace-module.patch
---

diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c
index f6ae6830b34..bbaad357f5d 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 (kernel_is_locked_down("MMIO trace testing"))
+		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");