Messages in this thread Patch in this message | | | From | David Howells <> | Subject | [PATCH 17/30] acpi: Disable ACPI table override if the kernel is locked down | Date | Thu, 9 Nov 2017 17:32:45 +0000 |
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From: Linn Crosetto <linn@hpe.com>
>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 <linn@hpe.com> Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: "Lee, Chun-Yi" <jlee@suse.com> cc: linux-acpi@vger.kernel.org ---
drivers/acpi/tables.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c index 80ce2a7d224b..5cc13c42daf9 100644 --- a/drivers/acpi/tables.c +++ b/drivers/acpi/tables.c @@ -526,6 +526,11 @@ 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);
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