Re: [PATCH v3 7/8] common: add support to fallback to plain SHA256

On Mon, 21 Jun 2021 at 14:24, Steffen Jaeckel jaeckel-floss@eyet-services.de wrote:

In case crypt-based hashing is enabled this will be the default mechanism that is used. If a user wants to have support for both, the environment variable `bootstopusesha256` can be set to `true` to allow plain SHA256 based hashing of the password.

Signed-off-by: Steffen Jaeckel jaeckel-floss@eyet-services.de

(no changes since v1)

common/Kconfig.boot | 8 ++++++++ common/autoboot.c | 22 +++++++++++++++++++++- 2 files changed, 29 insertions(+), 1 deletion(-)

Reviewed-by: Simon Glass sjg@chromium.org

nits below

diff --git a/common/Kconfig.boot b/common/Kconfig.boot index d19bc32836..b04a6c98e5 100644 --- a/common/Kconfig.boot +++ b/common/Kconfig.boot @@ -834,6 +834,14 @@ config AUTOBOOT_ENCRYPTION This provides a way to ship a secure production device which can also be accessed at the U-Boot command line.

+config AUTOBOOT_SHA256_FALLBACK_ENABLE

Drop _ENABLE

•   bool "Allow fallback from crypt-hashed password to sha256"
  

•   depends on AUTOBOOT_ENCRYPTION && CRYPT_PW
  

•   help
  

•     This option adds support to fall back from crypt-hashed
  

•     passwords to checking a SHA256 hashed password in case the
  

•     'bootstopusesha256' environment variable is set to 'true'.
  

config AUTOBOOT_DELAY_STR string "Delay autobooting via specific input key / string" depends on AUTOBOOT_KEYED && !AUTOBOOT_ENCRYPTION diff --git a/common/autoboot.c b/common/autoboot.c index 1eeabf0b1a..c6f550b8a7 100644 --- a/common/autoboot.c +++ b/common/autoboot.c @@ -305,6 +305,26 @@ static void flush_stdin(void) (void)getchar(); }

+/**

• • fallback_to_sha256() - check whether we should fall back to sha256

• •                    password checking
    

• • This checks for the environment variable `bootstopusesha256` in case
• • sha256-fallback has been enabled via the config setting
• • `AUTOBOOT_SHA256_FALLBACK_ENABLE`.
• • @return 0 if we must not fall-back, 1 if plain sha256 should be tried

false / true

• */

+static int fallback_to_sha256(void)

bool

+{

•   if (IS_ENABLED(CONFIG_AUTOBOOT_SHA256_FALLBACK_ENABLE))
  

•           return env_get_yesno("bootstopusesha256") == 1;
  

•   else if (IS_ENABLED(CONFIG_CRYPT_PW))
  

•           return 0;
  

false

•   else
  

•           return 1;
  

true

+}

/***************************************************************************

• Watch for 'delay' seconds for autoboot stop or autoboot delay string.
• returns: 0 - no key string, allow autoboot 1 - got key string, abort

@@ -325,7 +345,7 @@ static int abortboot_key_sequence(int bootdelay) # endif

    if (IS_ENABLED(CONFIG_AUTOBOOT_ENCRYPTION)) {

•           if (IS_ENABLED(CONFIG_CRYPT_PW))
  

•           if (IS_ENABLED(CONFIG_CRYPT_PW) && !fallback_to_sha256())
                    abort = passwd_abort_crypt(etime);
            else
                    abort = passwd_abort_sha256(etime);
  

-- 2.31.1

Regards, Simon