Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934881AbcKWJaD (ORCPT ); Wed, 23 Nov 2016 04:30:03 -0500 Received: from mailout2.hostsharing.net ([83.223.90.233]:39799 "EHLO mailout2.hostsharing.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933152AbcKWJ36 (ORCPT ); Wed, 23 Nov 2016 04:29:58 -0500 Date: Wed, 23 Nov 2016 10:31:23 +0100 From: Lukas Wunner To: David Howells Cc: linux-efi@vger.kernel.org, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/6] efi: Get the secure boot status [ver #2] Message-ID: <20161123093122.GB2071@wunner.de> References: <147986054870.13790.8640536414645705863.stgit@warthog.procyon.org.uk> <147986057768.13790.3027173260868896792.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <147986057768.13790.3027173260868896792.stgit@warthog.procyon.org.uk> User-Agent: Mutt/1.6.1 (2016-04-27) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7749 Lines: 232 On Wed, Nov 23, 2016 at 12:22:57AM +0000, David Howells wrote: > Get the firmware's secure-boot status in the kernel boot wrapper and stash > it somewhere that the main kernel image can find. > > The efi_get_secureboot() function is extracted from the arm stub and (a) > generalised so that it can be called from x86 and (b) made to use > efi_call_runtime() so that it can be run in mixed-mode. > > Suggested-by: Lukas Wunner > Signed-off-by: David Howells > --- > > Documentation/x86/zero-page.txt | 2 + > arch/x86/boot/compressed/eboot.c | 2 + > arch/x86/include/uapi/asm/bootparam.h | 3 + > drivers/firmware/efi/libstub/Makefile | 2 - > drivers/firmware/efi/libstub/arm-stub.c | 46 ------------------- > drivers/firmware/efi/libstub/secureboot.c | 71 +++++++++++++++++++++++++++++ > include/linux/efi.h | 2 + > 7 files changed, 80 insertions(+), 48 deletions(-) > create mode 100644 drivers/firmware/efi/libstub/secureboot.c > > diff --git a/Documentation/x86/zero-page.txt b/Documentation/x86/zero-page.txt > index 95a4d34af3fd..b8527c6b7646 100644 > --- a/Documentation/x86/zero-page.txt > +++ b/Documentation/x86/zero-page.txt > @@ -31,6 +31,8 @@ Offset Proto Name Meaning > 1E9/001 ALL eddbuf_entries Number of entries in eddbuf (below) > 1EA/001 ALL edd_mbr_sig_buf_entries Number of entries in edd_mbr_sig_buffer > (below) > +1EB/001 ALL kbd_status Numlock is enabled > +1EC/001 ALL secure_boot Secure boot is enabled in the firmware > 1EF/001 ALL sentinel Used to detect broken bootloaders > 290/040 ALL edd_mbr_sig_buffer EDD MBR signatures > 2D0/A00 ALL e820_map E820 memory map table > diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c > index c8c32ebcdfdb..6023b0e6f2af 100644 > --- a/arch/x86/boot/compressed/eboot.c > +++ b/arch/x86/boot/compressed/eboot.c > @@ -1158,6 +1158,8 @@ struct boot_params *efi_main(struct efi_config *c, > else > setup_boot_services32(efi_early); > > + boot_params->secure_boot = (efi_get_secureboot(sys_table) == 1); > + It just occurred to me that the boot_params struct is populated in make_boot_params(), perhaps it makes sense to move this line there. Otherwise LGTM. Thanks, Lukas > setup_graphics(boot_params); > > setup_efi_pci(boot_params); > diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h > index b10bf319ed20..5138dacf8bb8 100644 > --- a/arch/x86/include/uapi/asm/bootparam.h > +++ b/arch/x86/include/uapi/asm/bootparam.h > @@ -135,7 +135,8 @@ struct boot_params { > __u8 eddbuf_entries; /* 0x1e9 */ > __u8 edd_mbr_sig_buf_entries; /* 0x1ea */ > __u8 kbd_status; /* 0x1eb */ > - __u8 _pad5[3]; /* 0x1ec */ > + __u8 secure_boot; /* 0x1ec */ > + __u8 _pad5[2]; /* 0x1ed */ > /* > * The sentinel is set to a nonzero value (0xff) in header.S. > * > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile > index 6621b13c370f..9af966863612 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -28,7 +28,7 @@ OBJECT_FILES_NON_STANDARD := y > # Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. > KCOV_INSTRUMENT := n > > -lib-y := efi-stub-helper.o gop.o > +lib-y := efi-stub-helper.o gop.o secureboot.o > > # include the stub's generic dependencies from lib/ when building for ARM/arm64 > arm-deps := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c fdt_empty_tree.c fdt_sw.c sort.c > diff --git a/drivers/firmware/efi/libstub/arm-stub.c b/drivers/firmware/efi/libstub/arm-stub.c > index b4f7d78f9e8b..552ee61ddbed 100644 > --- a/drivers/firmware/efi/libstub/arm-stub.c > +++ b/drivers/firmware/efi/libstub/arm-stub.c > @@ -20,52 +20,6 @@ > > bool __nokaslr; > > -static int efi_get_secureboot(efi_system_table_t *sys_table_arg) > -{ > - static efi_char16_t const sb_var_name[] = { > - 'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0 }; > - static efi_char16_t const sm_var_name[] = { > - 'S', 'e', 't', 'u', 'p', 'M', 'o', 'd', 'e', 0 }; > - > - efi_guid_t var_guid = EFI_GLOBAL_VARIABLE_GUID; > - efi_get_variable_t *f_getvar = sys_table_arg->runtime->get_variable; > - u8 val; > - unsigned long size = sizeof(val); > - efi_status_t status; > - > - status = f_getvar((efi_char16_t *)sb_var_name, (efi_guid_t *)&var_guid, > - NULL, &size, &val); > - > - if (status != EFI_SUCCESS) > - goto out_efi_err; > - > - if (val == 0) > - return 0; > - > - status = f_getvar((efi_char16_t *)sm_var_name, (efi_guid_t *)&var_guid, > - NULL, &size, &val); > - > - if (status != EFI_SUCCESS) > - goto out_efi_err; > - > - if (val == 1) > - return 0; > - > - return 1; > - > -out_efi_err: > - switch (status) { > - case EFI_NOT_FOUND: > - return 0; > - case EFI_DEVICE_ERROR: > - return -EIO; > - case EFI_SECURITY_VIOLATION: > - return -EACCES; > - default: > - return -EINVAL; > - } > -} > - > efi_status_t efi_open_volume(efi_system_table_t *sys_table_arg, > void *__image, void **__fh) > { > diff --git a/drivers/firmware/efi/libstub/secureboot.c b/drivers/firmware/efi/libstub/secureboot.c > new file mode 100644 > index 000000000000..466fe24f5866 > --- /dev/null > +++ b/drivers/firmware/efi/libstub/secureboot.c > @@ -0,0 +1,71 @@ > +/* > + * Secure boot handling. > + * > + * Copyright (C) 2013,2014 Linaro Limited > + * Roy Franz + * Copyright (C) 2013 Red Hat, Inc. > + * Mark Salter > + * > + * This file is part of the Linux kernel, and is made available under the > + * terms of the GNU General Public License version 2. > + * > + */ > + > +#include > +#include > + > +/* BIOS variables */ > +static const efi_guid_t efi_variable_guid = EFI_GLOBAL_VARIABLE_GUID; > +static const efi_char16_t const efi_SecureBoot_name[] = { > + 'S', 'e', 'c', 'u', 'r', 'e', 'B', 'o', 'o', 't', 0 > +}; > +static const efi_char16_t const efi_SetupMode_name[] = { > + 'S', 'e', 't', 'u', 'p', 'M', 'o', 'd', 'e', 0 > +}; > + > +#define get_efi_var(name, vendor, ...) \ > + efi_call_runtime(get_variable, \ > + (efi_char16_t *)(name), (efi_guid_t *)(vendor), \ > + __VA_ARGS__); > + > +/* > + * Determine whether we're in secure boot mode. > + */ > +int efi_get_secureboot(efi_system_table_t *sys_table_arg) > +{ > + u8 val; > + unsigned long size = sizeof(val); > + efi_status_t status; > + > + status = get_efi_var(efi_SecureBoot_name, &efi_variable_guid, > + NULL, &size, &val); > + > + if (status != EFI_SUCCESS) > + goto out_efi_err; > + > + if (val == 0) > + return 0; > + > + status = get_efi_var(efi_SetupMode_name, &efi_variable_guid, > + NULL, &size, &val); > + > + if (status != EFI_SUCCESS) > + goto out_efi_err; > + > + if (val == 1) > + return 0; > + > + return 1; > + > +out_efi_err: > + switch (status) { > + case EFI_NOT_FOUND: > + return 0; > + case EFI_DEVICE_ERROR: > + return -EIO; > + case EFI_SECURITY_VIOLATION: > + return -EACCES; > + default: > + return -EINVAL; > + } > +} > diff --git a/include/linux/efi.h b/include/linux/efi.h > index 24db4e5ec817..ff01ad6f2823 100644 > --- a/include/linux/efi.h > +++ b/include/linux/efi.h > @@ -1477,6 +1477,8 @@ efi_status_t efi_setup_gop(efi_system_table_t *sys_table_arg, > bool efi_runtime_disabled(void); > extern void efi_call_virt_check_flags(unsigned long flags, const char *call); > > +int efi_get_secureboot(efi_system_table_t *sys_table_arg); > + > /* > * Arch code can implement the following three template macros, avoiding > * reptition for the void/non-void return cases of {__,}efi_call_virt(): >