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,
Matthew Garrett <matthewgarrett@google.com>,
Matthew Garrett <mjg59@google.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
linux-efi@vger.kernel.org
Subject: [PATCH V34 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down
Date: Fri, 21 Jun 2019 17:03:57 -0700 [thread overview]
Message-ID: <20190622000358.19895-29-matthewgarrett@google.com> (raw)
In-Reply-To: <20190622000358.19895-1-matthewgarrett@google.com>
efivar_ssdt_load allows the kernel to import arbitrary ACPI code from an
EFI variable, which gives arbitrary code execution in ring 0. Prevent
that when the kernel is locked down.
Signed-off-by: Matthew Garrett <mjg59@google.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: linux-efi@vger.kernel.org
---
drivers/firmware/efi/efi.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 55b77c576c42..9f92a013ab27 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -31,6 +31,7 @@
#include <linux/acpi.h>
#include <linux/ucs2_string.h>
#include <linux/memblock.h>
+#include <linux/security.h>
#include <asm/early_ioremap.h>
@@ -242,6 +243,11 @@ static void generic_ops_unregister(void)
static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata;
static int __init efivar_ssdt_setup(char *str)
{
+ int ret = security_locked_down(LOCKDOWN_ACPI_TABLES);
+
+ if (ret)
+ return ret;
+
if (strlen(str) < sizeof(efivar_ssdt))
memcpy(efivar_ssdt, str, strlen(str));
else
--
2.22.0.410.gd8fdbe21b5-goog
next parent reply other threads:[~2019-06-22 0:05 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190622000358.19895-1-matthewgarrett@google.com>
2019-06-22 0:03 ` Matthew Garrett [this message]
2019-06-23 0:14 ` [PATCH V34 28/29] efi: Restrict efivar_ssdt_load when the kernel is locked down Kees Cook
2019-06-25 15:00 ` Ard Biesheuvel
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