From f474e1486b78ac15322f8a1cda48a32a1deff9d3 Mon Sep 17 00:00:00 2001 From: Matthew Garrett Date: Mon, 19 Aug 2019 17:17:50 -0700 Subject: ACPI: Limit access to custom_method when the kernel is locked down custom_method effectively allows arbitrary access to system memory, making it possible for an attacker to circumvent restrictions on module loading. Disable it if the kernel is locked down. Signed-off-by: Matthew Garrett Signed-off-by: David Howells Reviewed-by: Kees Cook cc: linux-acpi@vger.kernel.org Signed-off-by: James Morris --- drivers/acpi/custom_method.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'drivers') diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c index b2ef4c2ec955..7031307becd7 100644 --- a/drivers/acpi/custom_method.c +++ b/drivers/acpi/custom_method.c @@ -9,6 +9,7 @@ #include #include #include +#include #include "internal.h" @@ -29,6 +30,11 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf, struct acpi_table_header table; acpi_status status; + int ret; + + ret = security_locked_down(LOCKDOWN_ACPI_TABLES); + if (ret) + return ret; if (!(*ppos)) { /* parse the table header to get the table length */ -- cgit v1.2.3-59-g8ed1b