From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Matthew Garrett <matthewgarrett@google.com>
Cc: jmorris@namei.org, 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: Re: [PATCH V40 16/29] acpi: Disable ACPI table override if the kernel is locked down
Date: Wed, 21 Aug 2019 00:08:48 +0200 [thread overview]
Message-ID: <18886542.jEbjgeBmpC@kreacher> (raw)
In-Reply-To: <20190820001805.241928-17-matthewgarrett@google.com>
On Tuesday, August 20, 2019 2:17:52 AM CEST Matthew Garrett wrote:
> 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
> Signed-off-by: James Morris <jmorris@namei.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
> drivers/acpi/tables.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
> index de974322a197..b7c29a11c0c1 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
> @@ -577,6 +578,11 @@ 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);
>
prev parent reply other threads:[~2019-08-20 22:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190820001805.241928-1-matthewgarrett@google.com>
2019-08-20 0:17 ` [PATCH V40 14/29] ACPI: Limit access to custom_method when the kernel is locked down Matthew Garrett
2019-08-20 22:07 ` Rafael J. Wysocki
2019-08-20 0:17 ` [PATCH V40 15/29] acpi: Ignore acpi_rsdp kernel param when the kernel has been " Matthew Garrett
2019-08-20 22:08 ` Rafael J. Wysocki
2019-08-20 0:17 ` [PATCH V40 16/29] acpi: Disable ACPI table override if the kernel is " Matthew Garrett
2019-08-20 22:08 ` Rafael J. Wysocki [this message]
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