[PATCH 08/13] boot_verify: allow to force unsigned image to boot

Michael Olbrich m.olbrich at pengutronix.de
Sun Mar 26 01:25:58 PDT 2017


On Sun, Mar 26, 2017 at 04:44:59AM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> request confirmation before booting an unsigned image
> 
> with a default timeout
> 
> Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
> ---
>  commands/go.c         |  9 +++++++--
>  common/Kconfig        |  8 ++++++++
>  common/boot_verify.c  | 47 ++++++++++++++++++++++++++++++++++++++++++++---
>  common/bootm.c        |  6 ++++++
>  common/image-fit.c    |  1 +
>  common/uimage.c       |  1 +
>  include/boot_verify.h |  7 +++++++
>  7 files changed, 74 insertions(+), 5 deletions(-)
> 
> diff --git a/commands/go.c b/commands/go.c
> index e0385a977..919bcddc7 100644
> --- a/commands/go.c
> +++ b/commands/go.c
> @@ -38,8 +38,13 @@ static int do_go(int argc, char *argv[])
>  	if (argc < 2)
>  		return COMMAND_ERROR_USAGE;
>  
> -	if (boot_get_verify_mode() < BOOT_VERIFY_AVAILABLE)
> -		return -ESECVIOLATION;
> +	if (boot_get_verify_mode() < BOOT_VERIFY_AVAILABLE) {
> +		int is_sec;
> +
> +		is_sec = boot_can_start_unsigned();
> +		if (is_sec)
> +			return is_sec;
> +	}
>  
>  	if (!isdigit(*argv[1])) {
>  		fd = open(argv[1], O_RDONLY);
> diff --git a/common/Kconfig b/common/Kconfig
> index 00e98e859..2588651ae 100644
> --- a/common/Kconfig
> +++ b/common/Kconfig
> @@ -648,6 +648,14 @@ config BOOT_FORCE_SIGNED_IMAGES
>  	  are refused to boot. Effectively this means only Signed images can
>  	  be booted.
>  
> +config BOOT_FORCE_USER_SIGNED_IMAGES
> +	bool
> +	prompt "Force booting of signed images or confirm them"
> +	depends on HAS_SECURE_BOOT
> +	help
> +	  With this option enabled only signed images can be booted, unsigned images
> +	  need a user confirmation to boot.
> +
>  config BLSPEC
>  	depends on BLOCK
>  	depends on FLEXIBLE_BOOTARGS
> diff --git a/common/boot_verify.c b/common/boot_verify.c
> index 9cbeb7a65..07ae07e16 100644
> --- a/common/boot_verify.c
> +++ b/common/boot_verify.c
> @@ -1,9 +1,17 @@
> +/*
> + * Copyright (c) 2016 Sascha Hauer <s.hauer at pengutronix.de>, Pengutronix
> + * Copyright (c) 2017 Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
> + *
> + * Under GPLv2 Only
> + */

This belongs in the patch that introduces the file.

Michael

>  #include <common.h>
>  #include <boot_verify.h>
> +#include <console_countdown.h>
>  #include <globalvar.h>
>  #include <magicvar.h>
>  #include <init.h>
>  
> +static unsigned int boot_verify_confirm_timeout = 10;
>  static enum boot_verify boot_verify_mode = BOOT_VERIFY_HASH;
>  
>  enum boot_verify boot_get_verify_mode(void)
> @@ -14,6 +22,7 @@ enum boot_verify boot_get_verify_mode(void)
>  /* keep it for the most secure to the less */
>  static const char * const boot_verify_names[] = {
>  	[BOOT_VERIFY_SIGNATURE] = "signature",
> +	[BOOT_VERIFY_SIGNATURE_USER] = "signature-user",
>  	[BOOT_VERIFY_AVAILABLE] = "available",
>  	[BOOT_VERIFY_HASH] = "hash",
>  	[BOOT_VERIFY_NONE] = "none",
> @@ -40,6 +49,29 @@ void boot_set_is_secure_mode(int (*fn)(void))
>  	__is_secure_mode = fn;
>  }
>  
> +int boot_can_start_unsigned(void)
> +{
> +	int ret;
> +	char c;
> +	int timeout = boot_verify_confirm_timeout;
> +
> +	if (!is_secure_mode())
> +		return 0;
> +
> +	if (boot_verify_mode != BOOT_VERIFY_SIGNATURE_USER)
> +		return -ESECVIOLATION;
> +
> +	printf("Are you sure you wish to run an unsigned binary\n");
> +	printf("in a secure environment?\n");
> +	printf("press y to confirm\n");
> +
> +	ret = console_countdown(timeout, CONSOLE_COUNTDOWN_ANYKEY, &c);
> +	if (ret != -EINTR)
> +		return -ESECVIOLATION;
> +
> +	return c == 'y' ? 0 : -ESECVIOLATION;
> +}
> +
>  static int init_boot_verify(void)
>  {
>  	int size;
> @@ -47,16 +79,25 @@ static int init_boot_verify(void)
>  	if (IS_ENABLED(CONFIG_BOOT_FORCE_SIGNED_IMAGES))
>  		boot_verify_mode = BOOT_VERIFY_SIGNATURE;
>  
> -	if (is_secure_mode())
> -		size = 1;
> -	else
> +	if (is_secure_mode()) {
> +		if (IS_ENABLED(CONFIG_BOOT_FORCE_USER_SIGNED_IMAGES))
> +			size = 2;
> +		else
> +			size = 1;
> +	} else {
>  		size = ARRAY_SIZE(boot_verify_names);
> +	}
>  
>  	globalvar_add_simple_enum("boot.verify", (unsigned int *)&boot_verify_mode,
>  				  boot_verify_names, size);
>  
> +	globalvar_add_simple_int("boot.verify_confirm_timeout",
> +				 &boot_verify_confirm_timeout, "%u");
> +
>  	return 0;
>  }
>  late_initcall(init_boot_verify);
>  
>  BAREBOX_MAGICVAR_NAMED(global_boot_verify, global.boot.verify, "boot default verify level");
> +BAREBOX_MAGICVAR_NAMED(global_boot_verify_confirm_timeout, global.boot.verify_confirm_timeout,
> +		"Secure Boot Comfirm timeout in seconds before booting an unsigned image");
> diff --git a/common/bootm.c b/common/bootm.c
> index 1558f3c5d..73a3a99dd 100644
> --- a/common/bootm.c
> +++ b/common/bootm.c
> @@ -579,6 +579,12 @@ int bootm_boot(struct bootm_data *bootm_data)
>  		printf("Passing control to %s handler\n", handler->name);
>  	}
>  
> +	if (!handler->is_secure_supported && is_secure_mode()) {
> +		ret = boot_can_start_unsigned();
> +		if (ret)
> +			goto err_out;
> +	}
> +
>  	ret = handler->bootm(data);
>  	if (data->dryrun)
>  		printf("Dryrun. Aborted\n");
> diff --git a/common/image-fit.c b/common/image-fit.c
> index 53f3173fc..0df735062 100644
> --- a/common/image-fit.c
> +++ b/common/image-fit.c
> @@ -465,6 +465,7 @@ static int fit_config_verify_signature(struct fit_handle *handle, struct device_
>  	case BOOT_VERIFY_HASH:
>  		return 0;
>  	case BOOT_VERIFY_SIGNATURE:
> +	case BOOT_VERIFY_SIGNATURE_USER:
>  		ret = -EINVAL;
>  		break;
>  	case BOOT_VERIFY_AVAILABLE:
> diff --git a/common/uimage.c b/common/uimage.c
> index d1947aa11..f25341c15 100644
> --- a/common/uimage.c
> +++ b/common/uimage.c
> @@ -30,6 +30,7 @@
>  #include <rtc.h>
>  #include <filetype.h>
>  #include <memory.h>
> +#include <bootm.h>
>  
>  static inline int uimage_is_multi_image(struct uimage_handle *handle)
>  {
> diff --git a/include/boot_verify.h b/include/boot_verify.h
> index ee830bf5c..12dcfbfdc 100644
> --- a/include/boot_verify.h
> +++ b/include/boot_verify.h
> @@ -3,6 +3,7 @@
>  
>  enum boot_verify {
>  	BOOT_VERIFY_SIGNATURE,
> +	BOOT_VERIFY_SIGNATURE_USER,
>  	BOOT_VERIFY_AVAILABLE,
>  	BOOT_VERIFY_HASH,
>  	BOOT_VERIFY_NONE,
> @@ -19,10 +20,16 @@ static int inline is_secure_mode(void)
>  	return 0;
>  }
>  
> +static int inline boot_can_start_unsigned(void)
> +{
> +	return 0;
> +}
> +
>  static void inline boot_set_is_secure_mode(int (*fn)(void)) {}
>  #else
>  enum boot_verify boot_get_verify_mode(void);
>  int is_secure_mode(void);
> +int boot_can_start_unsigned(void);
>  void boot_set_is_secure_mode(int (*fn)(void));
>  #endif
>  
> -- 
> 2.11.0
> 
> 
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-- 
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