Hook into the autoboot flow as an alternative to the existing
mechanisms.
Signed-off-by: Steffen Jaeckel <jaeckel-fl...@eyet-services.de>
---
common/Kconfig.boot | 23 +++++++++++++---
common/autoboot.c | 67 +++++++++++++++++++++++++++++++++++++++------
2 files changed, 77 insertions(+), 13 deletions(-)
diff --git a/common/Kconfig.boot b/common/Kconfig.boot
index 9c335f4f8c..59fec48c5d 100644
--- a/common/Kconfig.boot
+++ b/common/Kconfig.boot
@@ -802,10 +802,16 @@ 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 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.
@@ -843,6 +849,15 @@ config AUTOBOOT_KEYED_CTRLC
Setting this variable provides an escape sequence from the
limited "password" strings.
+config AUTOBOOT_STOP_STR_CRYPT
+ string "Stop autobooting via crypt-hashed password"
+ depends on AUTOBOOT_KEYED && AUTOBOOT_ENCRYPTION
+ 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 support crypt options and saved in the environment.
+
config AUTOBOOT_STOP_STR_SHA256
string "Stop autobooting via SHA256 encrypted password"
depends on AUTOBOOT_KEYED && AUTOBOOT_ENCRYPTION
diff --git a/common/autoboot.c b/common/autoboot.c
index 0bb08e7a4c..732a01d0e5 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 +39,62 @@ 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_ENCRYPTION)
+#if defined(CONFIG_CRYPT_PW) && defined(CONFIG_AUTOBOOT_STOP_STR_CRYPT)
+#define AUTOBOOT_STOP_STR_ENC CONFIG_AUTOBOOT_STOP_STR_CRYPT
+#define HAS_STOP_STR_CRYPT 1
+#elif defined(CONFIG_AUTOBOOT_STOP_STR_SHA256)
+#define AUTOBOOT_STOP_STR_ENC CONFIG_AUTOBOOT_STOP_STR_SHA256
+#endif
+#endif
+#if !defined(AUTOBOOT_STOP_STR_ENC)
+#define AUTOBOOT_STOP_STR_ENC ""
#endif
-
#ifdef CONFIG_USE_AUTOBOOT_MENUKEY
#define AUTOBOOT_MENUKEY CONFIG_USE_AUTOBOOT_MENUKEY
#else
#define AUTOBOOT_MENUKEY 0
#endif
+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;
+
+ if (IS_ENABLED(HAS_STOP_STR_CRYPT) && !crypt_env_str)
+ crypt_env_str = AUTOBOOT_STOP_STR_ENC;
+
+ 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 >= MAX_DELAY_STOP_STR)
+ return 0;
+
+ presskey[presskey_len] = getchar();
+
+ if ((presskey[presskey_len] == '\r') ||
+ (presskey[presskey_len] == '\n')) {
+ presskey[presskey_len] = '\0';
+ crypt_compare(crypt_env_str, presskey, &abort);
+ /* 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 +134,7 @@ 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 = AUTOBOOT_STOP_STR_ENC;
presskey = malloc_cache_aligned(MAX_DELAY_STOP_STR);
c = strstr(sha_env_str, ":");
@@ -245,10 +290,14 @@ 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");
--
2.30.1
