Hook into the autoboot flow as an alternative to the existing mechanisms.
Signed-off-by: Steffen Jaeckel jaeckel-floss@eyet-services.de Reviewed-by: Simon Glass sjg@chromium.org ---
(no changes since v1)
common/Kconfig.boot | 38 ++++++++++++++++++--- common/autoboot.c | 80 ++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 104 insertions(+), 14 deletions(-)
diff --git a/common/Kconfig.boot b/common/Kconfig.boot index 89a3161f1f..410d117cdd 100644 --- a/common/Kconfig.boot +++ b/common/Kconfig.boot @@ -811,10 +811,17 @@ config AUTOBOOT_ENCRYPTION depends on AUTOBOOT_KEYED help This option allows a string to be entered into U-Boot to stop the - autoboot. The string itself is hashed and compared against the hash - in the environment variable 'bootstopkeysha256'. If it matches then - boot stops and a command-line prompt is presented. - + autoboot. + The behavior depends whether CONFIG_CRYPT_PW from lib is enabled + or not. + In case CONFIG_CRYPT_PW is enabled, the string will be forwarded + to the crypt-based functionality and be compared against the + string in the environment variable 'bootstopkeycrypt'. + In case CONFIG_CRYPT_PW is disabled the string itself is hashed + and compared against the hash in the environment variable + 'bootstopkeysha256'. + If it matches in either case then boot stops and + a command-line prompt is presented. This provides a way to ship a secure production device which can also be accessed at the U-Boot command line.
@@ -852,9 +859,30 @@ config AUTOBOOT_KEYED_CTRLC Setting this variable provides an escape sequence from the limited "password" strings.
+config AUTOBOOT_STOP_STR_ENABLE + bool "Enable fixed string to stop autobooting" + depends on AUTOBOOT_KEYED && AUTOBOOT_ENCRYPTION + help + This option enables the feature to add a fixed stop + string that is defined at compile time. + In every case it will be tried to load the stop + string from the environment. + In case this is enabled and there is no stop string + in the environment, this will be used as default value. + +config AUTOBOOT_STOP_STR_CRYPT + string "Stop autobooting via crypt-hashed password" + depends on AUTOBOOT_STOP_STR_ENABLE && CRYPT_PW + help + This option adds the feature to only stop the autobooting, + and therefore boot into the U-Boot prompt, when the input + string / password matches a values that is hashed via + one of the supported crypt-style password hashing options + and saved in the environment variable "bootstopkeycrypt". + config AUTOBOOT_STOP_STR_SHA256 string "Stop autobooting via SHA256 encrypted password" - depends on AUTOBOOT_KEYED && AUTOBOOT_ENCRYPTION + depends on AUTOBOOT_STOP_STR_ENABLE help This option adds the feature to only stop the autobooting, and therefore boot into the U-Boot prompt, when the input diff --git a/common/autoboot.c b/common/autoboot.c index 0bb08e7a4c..d52f88dd54 100644 --- a/common/autoboot.c +++ b/common/autoboot.c @@ -23,6 +23,7 @@ #include <linux/delay.h> #include <u-boot/sha256.h> #include <bootcount.h> +#include <crypt.h>
DECLARE_GLOBAL_DATA_PTR;
@@ -38,18 +39,75 @@ DECLARE_GLOBAL_DATA_PTR; static int stored_bootdelay; static int menukey;
-#ifdef CONFIG_AUTOBOOT_ENCRYPTION -#define AUTOBOOT_STOP_STR_SHA256 CONFIG_AUTOBOOT_STOP_STR_SHA256 -#else -#define AUTOBOOT_STOP_STR_SHA256 "" +#if !defined(CONFIG_AUTOBOOT_STOP_STR_CRYPT) +#define CONFIG_AUTOBOOT_STOP_STR_CRYPT "" +#endif +#if !defined(CONFIG_AUTOBOOT_STOP_STR_SHA256) +#define CONFIG_AUTOBOOT_STOP_STR_SHA256 "" #endif - #ifdef CONFIG_USE_AUTOBOOT_MENUKEY #define AUTOBOOT_MENUKEY CONFIG_USE_AUTOBOOT_MENUKEY #else #define AUTOBOOT_MENUKEY 0 #endif
+/** + * passwd_abort_crypt() - check for a crypt-style hashed key sequence to abort booting + * + * This checks for the user entering a password within a given time. + * + * The entered password is hashed via one of the crypt-style hash methods + * and compared to the pre-defined value from either + * the environment variable "bootstopkeycrypt" + * or + * the config value CONFIG_AUTOBOOT_STOP_STR_CRYPT + * + * @etime: Timeout value ticks (stop when get_ticks() reachs this) + * @return 0 if autoboot should continue, 1 if it should stop + */ +static int passwd_abort_crypt(uint64_t etime) +{ + const char *crypt_env_str = env_get("bootstopkeycrypt"); + char presskey[MAX_DELAY_STOP_STR]; + u_int presskey_len = 0; + int abort = 0; + int err; + + if (IS_ENABLED(CONFIG_AUTOBOOT_STOP_STR_ENABLE) && !crypt_env_str) + crypt_env_str = CONFIG_AUTOBOOT_STOP_STR_CRYPT; + + if (!crypt_env_str) + return 0; + + /* We expect the stop-string to be newline-terminated */ + do { + if (tstc()) { + /* Check for input string overflow */ + if (presskey_len >= sizeof(presskey)) + return 0; + + presskey[presskey_len] = getchar(); + + if ((presskey[presskey_len] == '\r') || + (presskey[presskey_len] == '\n')) { + presskey[presskey_len] = '\0'; + err = crypt_compare(crypt_env_str, presskey, + &abort); + if (err) + debug_bootkeys( + "crypt_compare() failed with: %s\n", + errno_str(err)); + /* you had one chance */ + break; + } else { + presskey_len++; + } + } + } while (get_ticks() <= etime); + + return abort; +} + /* * Use a "constant-length" time compare function for this * hash compare: @@ -89,7 +147,7 @@ static int passwd_abort_sha256(uint64_t etime) int ret;
if (sha_env_str == NULL) - sha_env_str = AUTOBOOT_STOP_STR_SHA256; + sha_env_str = CONFIG_AUTOBOOT_STOP_STR_SHA256;
presskey = malloc_cache_aligned(MAX_DELAY_STOP_STR); c = strstr(sha_env_str, ":"); @@ -245,10 +303,14 @@ static int abortboot_key_sequence(int bootdelay) printf(CONFIG_AUTOBOOT_PROMPT, bootdelay); # endif
- if (IS_ENABLED(CONFIG_AUTOBOOT_ENCRYPTION)) - abort = passwd_abort_sha256(etime); - else + if (IS_ENABLED(CONFIG_AUTOBOOT_ENCRYPTION)) { + if (IS_ENABLED(CONFIG_CRYPT_PW)) + abort = passwd_abort_crypt(etime); + else + abort = passwd_abort_sha256(etime); + } else { abort = passwd_abort_key(etime); + } if (!abort) debug_bootkeys("key timeout\n");