Re: [PATCH V34 16/29] acpi: Disable ACPI table override if the kernel is locked down
From: Kees Cook <hidden>
Date: 2019-06-23 00:00:18
Also in:
linux-acpi, linux-api, lkml
On Fri, Jun 21, 2019 at 05:03:45PM -0700, Matthew Garrett wrote:
From: Linn Crosetto <redacted> 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 <redacted>
Reviewed-by: Kees Cook <redacted> -Kees
quoted hunk ↗ jump to hunk
Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Matthew Garrett <redacted> 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..41d9ccd0e075 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c@@ -34,6 +34,7 @@ #include <linux/memblock.h> #include <linux/earlycpio.h> #include <linux/initrd.h> +#include <linux/security.h> #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_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
-- Kees Cook