[PATCH V34 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down

Matthew Garrett
2019-06-22T00:04:45Z

From: Josh Boyer <jwboyer@redhat.com>

This option allows userspace to pass the RSDP address to the kernel, which
makes it possible for a user to modify the workings of hardware . Reject
the option when the kernel is locked down.

Signed-off-by: Josh Boyer <jwboyer@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
cc: Dave Young <dyoung@redhat.com>
cc: linux-acpi@vger.kernel.org
---
drivers/acpi/osl.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index f29e427d0d1d..60cda8a0f36b 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -40,6 +40,7 @@
#include <linux/list.h>
#include <linux/jiffies.h>
#include <linux/semaphore.h>
+#include <linux/security.h>

#include <asm/io.h>
#include <linux/uaccess.h>
@@ -194,7 +195,7 @@ acpi_physical_address __init acpi_os_get_root_pointer(void)
acpi_physical_address pa;

#ifdef CONFIG_KEXEC
- if (acpi_rsdp)
+ if (acpi_rsdp && !security_locked_down(LOCKDOWN_ACPI_TABLES))
return acpi_rsdp;
#endif
pa = acpi_arch_get_root_pointer();
--
2.22.0.410.gd8fdbe21b5-goog