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authorMatthew Garrett <matthewgarrett@google.com>2019-08-19 17:18:04 -0700
committerJames Morris <jmorris@namei.org>2019-08-19 21:54:17 -0700
commit1957a85b0032a81e6482ca4aab883643b8dae06e (patch)
tree5adf9fd932190f269677c6a29090ebbec6569a6a /drivers/firmware
parentccbd54ff54e8b1880456b81c4aea352ebe208843 (diff)
efi: Restrict efivar_ssdt_load when the kernel is locked down
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> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Reviewed-by: Kees Cook <keescook@chromium.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: linux-efi@vger.kernel.org Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'drivers/firmware')
-rw-r--r--drivers/firmware/efi/efi.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 4b7cf7bc0ded..5f98374f77f4 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -30,6 +30,7 @@
#include <linux/acpi.h>
#include <linux/ucs2_string.h>
#include <linux/memblock.h>
+#include <linux/security.h>
#include <asm/early_ioremap.h>
@@ -241,6 +242,11 @@ 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