From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: [PATCH V33 17/30] acpi: Disable ACPI table override if the kernel is locked down Date: Thu, 20 Jun 2019 18:19:28 -0700 Message-ID: <20190621011941.186255-18-matthewgarrett@google.com> References: <20190621011941.186255-1-matthewgarrett@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20190621011941.186255-1-matthewgarrett@google.com> Sender: linux-kernel-owner@vger.kernel.org To: jmorris@namei.org Cc: linux-security@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Linn Crosetto , David Howells , Matthew Garrett , linux-acpi@vger.kernel.org List-Id: linux-api@vger.kernel.org From: Linn Crosetto >>From the kernel documentation (initrd_table_override.txt): If the ACPI_INITRD_TABLE_OVERRIDE compile option is true, it is possible to override nearly any ACPI table provided by the BIOS with an instrumented, modified one. When lockdown is enabled, the kernel should disallow any unauthenticated changes to kernel space. ACPI tables contain code invoked by the kernel, so do not allow ACPI tables to be overridden if the kernel is locked down. Signed-off-by: Linn Crosetto Signed-off-by: David Howells Signed-off-by: Matthew Garrett cc: linux-acpi@vger.kernel.org --- drivers/acpi/tables.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index 8fccbe49612a..f8e7d70f07ee 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c @@ -34,6 +34,7 @@ #include #include #include +#include #include "internal.h" #ifdef CONFIG_ACPI_CUSTOM_DSDT @@ -539,6 +540,11 @@ void __init acpi_table_upgrade(void) if (table_nr == 0) return; + if (security_is_locked_down(LOCKDOWN_ACPI_TABLES)) { + pr_notice("kernel is locked down, ignoring table override\n"); + return; + } + acpi_tables_addr = memblock_find_in_range(0, ACPI_TABLE_UPGRADE_MAX_PHYS, all_tables_size, PAGE_SIZE); -- 2.22.0.410.gd8fdbe21b5-goog