Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753475AbaDYQKs (ORCPT ); Fri, 25 Apr 2014 12:10:48 -0400 Received: from mail-we0-f170.google.com ([74.125.82.170]:54977 "EHLO mail-we0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753430AbaDYQKn (ORCPT ); Fri, 25 Apr 2014 12:10:43 -0400 From: Leif Lindholm To: linux-kernel@vger.kernel.org, linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org Cc: matt.fleming@intel.com, catalin.marinas@arm.com, msalter@redhat.com, grant.likely@linaro.org, roy.franz@linaro.org, ard.biesheuvel@linaro.org, mark.rutland@arm.com, linux-doc@vger.kernel.org Subject: [PATCH v2 10/10] efi/arm64: ignore dtb= when UEFI SecureBoot is enabled Date: Fri, 25 Apr 2014 17:09:14 +0100 Message-Id: <1398442154-19974-11-git-send-email-leif.lindholm@linaro.org> X-Mailer: git-send-email 1.7.10.4 In-Reply-To: <1398442154-19974-1-git-send-email-leif.lindholm@linaro.org> References: <1398442154-19974-1-git-send-email-leif.lindholm@linaro.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ard Biesheuvel Loading unauthenticated FDT blobs directly from storage is a security hazard, so this should only be allowed when running with UEFI Secure Boot disabled. Signed-off-by: Ard Biesheuvel Signed-off-by: Leif Lindholm --- drivers/firmware/efi/arm-stub.c | 39 +++++++++++++++++++++++++++++++++++---- 1 file changed, 35 insertions(+), 4 deletions(-) diff --git a/drivers/firmware/efi/arm-stub.c b/drivers/firmware/efi/arm-stub.c index 19239a9..41114ce 100644 --- a/drivers/firmware/efi/arm-stub.c +++ b/drivers/firmware/efi/arm-stub.c @@ -12,6 +12,30 @@ * */ +static int __init efi_secureboot_enabled(efi_system_table_t *sys_table_arg) +{ + static efi_guid_t const var_guid __initconst = EFI_GLOBAL_VARIABLE_GUID; + static efi_char16_t const var_name[] __initconst = { + 'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0 }; + + efi_get_variable_t *f_getvar = sys_table_arg->runtime->get_variable; + unsigned long size = sizeof(u8); + efi_status_t status; + u8 val; + + status = f_getvar((efi_char16_t *)var_name, (efi_guid_t *)&var_guid, + NULL, &size, &val); + + switch (status) { + case EFI_SUCCESS: + return val; + case EFI_NOT_FOUND: + return 0; + default: + return 1; + } +} + static efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg, void *__image, void **__fh) { @@ -144,7 +168,7 @@ unsigned long __init efi_entry(void *handle, efi_system_table_t *sys_table, /* addr/point and size pairs for memory management*/ unsigned long initrd_addr; u64 initrd_size = 0; - unsigned long fdt_addr; /* Original DTB */ + unsigned long fdt_addr = 0; /* Original DTB */ u64 fdt_size = 0; /* We don't get size from configuration table */ char *cmdline_ptr = NULL; int cmdline_size = 0; @@ -196,9 +220,13 @@ unsigned long __init efi_entry(void *handle, efi_system_table_t *sys_table, goto fail_free_image; } - /* Load a device tree from the configuration table, if present. */ - fdt_addr = (uintptr_t)get_fdt(sys_table); - if (!fdt_addr) { + /* + * Unauthenticated device tree data is a security hazard, so + * ignore 'dtb=' unless UEFI Secure Boot is disabled. + */ + if (efi_secureboot_enabled(sys_table)) { + pr_efi(sys_table, "UEFI Secure Boot is enabled.\n"); + } else { status = handle_cmdline_files(sys_table, image, cmdline_ptr, "dtb=", ~0UL, (unsigned long *)&fdt_addr, @@ -209,6 +237,9 @@ unsigned long __init efi_entry(void *handle, efi_system_table_t *sys_table, goto fail_free_cmdline; } } + if (!fdt_addr) + /* Look for a device tree configuration table entry. */ + fdt_addr = (uintptr_t)get_fdt(sys_table); status = handle_cmdline_files(sys_table, image, cmdline_ptr, "initrd=", dram_base + SZ_512M, -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/