From: David Howells <dhowells@xxxxxxxxxx> 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 <tglx@xxxxxxxxxxxxx> Signed-off-by: David Howells <dhowells@xxxxxxxxxx Signed-off-by: Matthew Garrett <mjg59@xxxxxxxxxx> cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> cc: Steven Rostedt <rostedt@xxxxxxxxxxx> cc: Ingo Molnar <mingo@xxxxxxxxxx> cc: "H. Peter Anvin" <hpa@xxxxxxxxx> cc: x86@xxxxxxxxxx --- 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