From c8fefbf41a90a24cf42b3465a35f8e6f0e8b8d06 Mon Sep 17 00:00:00 2001 From: Linn Crosetto Date: Mon, 18 Feb 2019 12:45:00 +0000 Subject: [PATCH] acpi: Disable ACPI table override if the kernel is locked down 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 securelevel is set, 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 Reviewed-by: "Lee, Chun-Yi" cc: linux-acpi@vger.kernel.org Gbp-Pq: Topic features/all/lockdown Gbp-Pq: Name 0017-acpi-Disable-ACPI-table-override-if-the-kernel-is-lo.patch --- drivers/acpi/tables.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index de974322a19..7445f3960f3 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c @@ -577,6 +577,11 @@ void __init acpi_table_upgrade(void) if (table_nr == 0) return; + if (kernel_is_locked_down("ACPI table override")) { + 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); -- 2.30.2