x86/mmiotrace: Lock down the testmmiotrace module (906357f7) · Commits · 戴 / test

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@linutronix.de> Signed-off-by:

David Howells <dhowells@redhat.com> Signed-off-by:

Matthew Garrett <mjg59@google.com> Acked-by:

Steven Rostedt (VMware) <rostedt@goodmis.org> Reviewed-by:

Kees Cook <keescook@chromium.org> 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 Signed-off-by:

James Morris <jmorris@namei.org>

arch/x86/mm/testmmiotrace.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -8,6 +8,7 @@
		#include <linux/module.h>
		#include <linux/io.h>
		#include <linux/mmiotrace.h>
		#include <linux/security.h>

		static unsigned long mmio_address;
		module_param_hw(mmio_address, ulong, iomem, 0);
		@@ -115,6 +116,10 @@ static void do_test_bulk_ioremapping(void)
		static int __init init(void)
		{
		unsigned long size = (read_far) ? (8 << 20) : (16 << 10);
		int ret = security_locked_down(LOCKDOWN_MMIOTRACE);

		if (ret)
		return ret;

		if (mmio_address == 0) {
		pr_err("you have to use the module argument mmio_address.\n");

include/linux/security.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -114,6 +114,7 @@ enum lockdown_reason {
		LOCKDOWN_PCMCIA_CIS,
		LOCKDOWN_TIOCSSERIAL,
		LOCKDOWN_MODULE_PARAMETERS,
		LOCKDOWN_MMIOTRACE,
		LOCKDOWN_INTEGRITY_MAX,
		LOCKDOWN_CONFIDENTIALITY_MAX,
		};

security/lockdown/lockdown.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -29,6 +29,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
		[LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
		[LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
		[LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
		[LOCKDOWN_MMIOTRACE] = "unsafe mmio",
		[LOCKDOWN_INTEGRITY_MAX] = "integrity",
		[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
		};

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