From: Matthew Garrett <matthewgarrett@google.com>
To: jmorris@namei.org
Cc: linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
Linn Crosetto <linn@hpe.com>, David Howells <dhowells@redhat.com>,
Matthew Garrett <mjg59@google.com>,
linux-acpi@vger.kernel.org
Subject: [PATCH V34 16/29] acpi: Disable ACPI table override if the kernel is locked down
Date: Fri, 21 Jun 2019 17:03:45 -0700 [thread overview]
Message-ID: <20190622000358.19895-17-matthewgarrett@google.com> (raw)
In-Reply-To: <20190622000358.19895-1-matthewgarrett@google.com>
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 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 <linn@hpe.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
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
next prev parent reply other threads:[~2019-06-22 0:06 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190622000358.19895-1-matthewgarrett@google.com>
2019-06-22 0:03 ` [PATCH V34 14/29] ACPI: Limit access to custom_method when the kernel is locked down Matthew Garrett
2019-06-22 23:59 ` Kees Cook
2019-06-22 0:03 ` [PATCH V34 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-06-22 23:59 ` Kees Cook
2019-06-22 0:03 ` Matthew Garrett [this message]
2019-06-23 0:00 ` [PATCH V34 16/29] acpi: Disable ACPI table override if the kernel is " Kees Cook
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