From: David Howells <dhowe...@redhat.com>
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. This is
a runtime check rather than buildtime in order to allow configurations
where the same kernel may be run in both locked down or permissive modes
depending on local policy.
Suggested-by: Thomas Gleixner <t...@linutronix.de>
Signed-off-by: David Howells <dhowe...@redhat.com
Signed-off-by: Matthew Garrett <mj...@google.com>
cc: Thomas Gleixner <t...@linutronix.de>
cc: Steven Rostedt <rost...@goodmis.org>
cc: Ingo Molnar <mi...@kernel.org>
cc: "H. Peter Anvin" <h...@zytor.com>
cc: x...@kernel.org
---
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 f6ae6830b341..9e8ad665f354 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", LOCKDOWN_INTEGRITY))
+ 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");
--
2.21.0.392.gf8f6787159e-goog
