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Message-ID: <20170526075903.GB15587@linux-l9pv.suse>
Date: Fri, 26 May 2017 15:59:03 +0800
From: joeyli <jlee@...e.com>
To: David Howells <dhowells@...hat.com>
Cc: ard.biesheuvel@...aro.org, matthew.garrett@...ula.com,
linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/5] efi: Move the x86 secure boot switch to generic code
Hi David,
On Wed, May 24, 2017 at 03:45:25PM +0100, David Howells wrote:
> Move the switch-statement in x86's setup_arch() that inteprets the
> secure_boot boot parameter to generic code.
>
> Suggested-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Signed-off-by: David Howells <dhowells@...hat.com>
I reviewed the context for this patch.
Reviewed-by: Joey Lee <jlee@...e.com>
Regards
Joey Lee
> ---
>
> arch/x86/kernel/setup.c | 14 +-------------
> drivers/firmware/efi/Kconfig | 23 +++++++++++++++++++++++
> drivers/firmware/efi/Makefile | 1 +
> drivers/firmware/efi/secureboot.c | 34 ++++++++++++++++++++++++++++++++++
> include/linux/efi.h | 6 ++++++
> 5 files changed, 65 insertions(+), 13 deletions(-)
> create mode 100644 drivers/firmware/efi/secureboot.c
>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 0b4d3c686b1e..8bffbd8d2c1c 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -1177,19 +1177,7 @@ void __init setup_arch(char **cmdline_p)
> /* Allocate bigger log buffer */
> setup_log_buf(1);
>
> - if (efi_enabled(EFI_BOOT)) {
> - switch (boot_params.secure_boot) {
> - case efi_secureboot_mode_disabled:
> - pr_info("Secure boot disabled\n");
> - break;
> - case efi_secureboot_mode_enabled:
> - pr_info("Secure boot enabled\n");
> - break;
> - default:
> - pr_info("Secure boot could not be determined\n");
> - break;
> - }
> - }
> + efi_set_secure_boot(boot_params.secure_boot);
>
> reserve_initrd();
>
> diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
> index 394db40ed374..c40fdeaf9a45 100644
> --- a/drivers/firmware/efi/Kconfig
> +++ b/drivers/firmware/efi/Kconfig
> @@ -84,6 +84,29 @@ config EFI_PARAMS_FROM_FDT
> config EFI_RUNTIME_WRAPPERS
> bool
>
> +config EFI_SECURE_BOOT
> + bool "Support UEFI Secure Boot and lock down the kernel in secure boot mode"
> + default n
> + help
> + UEFI Secure Boot provides a mechanism for ensuring that the firmware
> + will only load signed bootloaders and kernels. Secure boot mode may
> + be determined from EFI variables provided by the system firmware if
> + not indicated by the boot parameters.
> +
> + Enabling this option turns on support for UEFI secure boot in the
> + kernel. This will result in various kernel facilities being locked
> + away from userspace if the kernel detects that it has been booted in
> + secure boot mode. If it hasn't been booted in secure boot mode, or
> + this cannot be determined, the lock down doesn't occur.
> +
> + The kernel facilities that get locked down include:
> + - Viewing or changing the kernel's memory
> + - Directly accessing ioports
> + - Directly specifying ioports and other hardware parameters to drivers
> + - Storing the kernel image unencrypted for hibernation
> + - Loading unsigned modules
> + - Kexec'ing unsigned images
> +
> config EFI_ARMSTUB
> bool
>
> diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
> index 0329d319d89a..9dfd8530063f 100644
> --- a/drivers/firmware/efi/Makefile
> +++ b/drivers/firmware/efi/Makefile
> @@ -23,6 +23,7 @@ obj-$(CONFIG_EFI_FAKE_MEMMAP) += fake_mem.o
> obj-$(CONFIG_EFI_BOOTLOADER_CONTROL) += efibc.o
> obj-$(CONFIG_EFI_TEST) += test/
> obj-$(CONFIG_EFI_DEV_PATH_PARSER) += dev-path-parser.o
> +obj-$(CONFIG_EFI_SECURE_BOOT) += secureboot.o
> obj-$(CONFIG_APPLE_PROPERTIES) += apple-properties.o
>
> arm-obj-$(CONFIG_EFI) := arm-init.o arm-runtime.o
> diff --git a/drivers/firmware/efi/secureboot.c b/drivers/firmware/efi/secureboot.c
> new file mode 100644
> index 000000000000..cf5bccae15e8
> --- /dev/null
> +++ b/drivers/firmware/efi/secureboot.c
> @@ -0,0 +1,34 @@
> +/* Core kernel secure boot support.
> + *
> + * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells (dhowells@...hat.com)
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public Licence
> + * as published by the Free Software Foundation; either version
> + * 2 of the Licence, or (at your option) any later version.
> + */
> +
> +#include <linux/efi.h>
> +#include <linux/kernel.h>
> +#include <linux/printk.h>
> +
> +/*
> + * Decide what to do when UEFI secure boot mode is enabled.
> + */
> +void __init efi_set_secure_boot(enum efi_secureboot_mode mode)
> +{
> + if (efi_enabled(EFI_BOOT)) {
> + switch (mode) {
> + case efi_secureboot_mode_disabled:
> + pr_info("Secure boot disabled\n");
> + break;
> + case efi_secureboot_mode_enabled:
> + pr_info("Secure boot enabled\n");
> + break;
> + default:
> + pr_info("Secure boot could not be determined\n");
> + break;
> + }
> + }
> +}
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index 8269bcb8ccf7..e2f53edccf15 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -1497,6 +1497,12 @@ enum efi_secureboot_mode {
> };
> enum efi_secureboot_mode efi_get_secureboot(efi_system_table_t *sys_table);
>
> +#ifdef CONFIG_EFI_SECURE_BOOT
> +void __init efi_set_secure_boot(enum efi_secureboot_mode mode);
> +#else
> +static inline void efi_set_secure_boot(enum efi_secureboot_mode mode) {}
> +#endif
> +
> /*
> * Arch code can implement the following three template macros, avoiding
> * reptition for the void/non-void return cases of {__,}efi_call_virt():
>
> --
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