From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Garrett Subject: [PATCH V33 30/30] efi: Restrict efivar_ssdt_load when the kernel is locked down Date: Thu, 20 Jun 2019 18:19:41 -0700 Message-ID: <20190621011941.186255-31-matthewgarrett@google.com> References: <20190621011941.186255-1-matthewgarrett@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20190621011941.186255-1-matthewgarrett@google.com> Sender: linux-kernel-owner@vger.kernel.org To: jmorris@namei.org Cc: linux-security@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Matthew Garrett , Matthew Garrett , Ard Biesheuvel , linux-efi@vger.kernel.org List-Id: linux-api@vger.kernel.org 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 Cc: Ard Biesheuvel Cc: linux-efi@vger.kernel.org --- drivers/firmware/efi/efi.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 55b77c576c42..a9ea649e0512 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -31,6 +31,7 @@ #include #include #include +#include #include @@ -242,6 +243,9 @@ static void generic_ops_unregister(void) static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata; static int __init efivar_ssdt_setup(char *str) { + if (security_is_locked_down(LOCKDOWN_ACPI_TABLES)) + return -EPERM; + if (strlen(str) < sizeof(efivar_ssdt)) memcpy(efivar_ssdt, str, strlen(str)); else -- 2.22.0.410.gd8fdbe21b5-goog