[PATCH 21/27] x86/mmiotrace: Lock down the testmmiotrace module
From: Matthew Garrett <hidden>
Date: 2019-03-07 00:00:58
Also in:
lkml
Subsystem:
the rest, tracing mmio accesses (mmiotrace), x86 architecture (32-bit and 64-bit), x86 mm · Maintainers:
Linus Torvalds, Steven Rostedt, Masami Hiramatsu, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra
From: David Howells <dhowells@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. Suggested-by: Thomas Gleixner <redacted> Signed-off-by: David Howells <dhowells@redhat.com cc: Thomas Gleixner <redacted> cc: Steven Rostedt <rostedt@goodmis.org> cc: Ingo Molnar <mingo@kernel.org> cc: "H. Peter Anvin" <hpa@zytor.com> cc: x86@kernel.org Signed-off-by: Matthew Garrett <redacted> --- 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..bbaad357f5d7 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");
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2.21.0.352.gf09ad66450-goog