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 <lcrosetto@gmail.com>,
David Howells <dhowells@redhat.com>,
Matthew Garrett <mjg59@google.com>,
Kees Cook <keescook@chromium.org>,
linux-acpi@vger.kernel.org
Subject: [PATCH V37 16/29] acpi: Disable ACPI table override if the kernel is locked down
Date: Wed, 31 Jul 2019 15:16:04 -0700 [thread overview]
Message-ID: <20190731221617.234725-17-matthewgarrett@google.com> (raw)
In-Reply-To: <20190731221617.234725-1-matthewgarrett@google.com>
From: Linn Crosetto <lcrosetto@gmail.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 <lcrosetto@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
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 b32327759380..180ac4329763 100644
--- a/drivers/acpi/tables.c
+++ b/drivers/acpi/tables.c
@@ -20,6 +20,7 @@
#include <linux/memblock.h>
#include <linux/earlycpio.h>
#include <linux/initrd.h>
+#include <linux/security.h>
#include "internal.h"
#ifdef CONFIG_ACPI_CUSTOM_DSDT
@@ -578,6 +579,11 @@ 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);
--
2.22.0.770.g0f2c4a37fd-goog
prev parent reply other threads:[~2019-07-31 22:19 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190731221617.234725-1-matthewgarrett@google.com>
2019-07-31 22:16 ` [PATCH V37 14/29] ACPI: Limit access to custom_method when the kernel is locked down Matthew Garrett
2019-07-31 22:16 ` [PATCH V37 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-07-31 22:16 ` Matthew Garrett [this message]
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