[PATCH v3] Add optional salt to AUTOBOOT_STOP_STR_SHA256

[Joel Peshkin <joel.peshkin@broadcom.com>]

Adds an optional SALT value to AUTOBOOT_STOP_STR_SHA256.   If a string
followed by a ":" is prepended to the sha256, the portion to the left
of the colon will be used as a salt and the password will be appended
to the salt before the sha256 is computed and compared.

Signed-off-by: Joel Peshkin <joel.peshkin@broadcom.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Bin Meng <bmeng.cn@gmail.com>
Cc: Patrick Delaunay <patrick.delaunay@st.com>
Cc: Heiko Schocher <hs@denx.de>
Cc: Heinrich Schuchardt <xypron.glpk@gmx.de>
Cc: Joel Peshkin <joel.peshkin@broadcom.com>
To: u-boot at lists.denx.de

---
Changes for v2:
   - Increase MAX_DELAY_STOP_STR
   - Check salt size against MAX_DELAY_STOP_STR before copying
   - Minor cleanup
Changes for v3:
   - Cleanup changing (c) to c after review feedback
---
 common/Kconfig.boot |  5 ++++-
 common/autoboot.c   | 12 ++++++++++--
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/common/Kconfig.boot b/common/Kconfig.boot
index 3f6d9c1..8a98672 100644
--- a/common/Kconfig.boot
+++ b/common/Kconfig.boot
@@ -819,7 +819,10 @@ config AUTOBOOT_STOP_STR_SHA256
 	  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 encypted via
-	  a SHA256 hash and saved in the environment.
+	  a SHA256 hash and saved in the environment variable
+	  "bootstopkeysha256". If the value in that variable
+	  includes a ":", the portion prior to the ":" will be treated
+	  as a salt value.
 
 config AUTOBOOT_USE_MENUKEY
 	bool "Allow a specify key to run a menu from the environment"
diff --git a/common/autoboot.c b/common/autoboot.c
index e628baf..ddb6246 100644
--- a/common/autoboot.c
+++ b/common/autoboot.c
@@ -25,7 +25,7 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
-#define MAX_DELAY_STOP_STR 32
+#define MAX_DELAY_STOP_STR 64
 
 #ifndef DEBUG_BOOTKEYS
 #define DEBUG_BOOTKEYS 0
@@ -80,6 +80,7 @@ static int passwd_abort_sha256(uint64_t etime)
 	u8 sha_env[SHA256_SUM_LEN];
 	u8 *sha;
 	char *presskey;
+	char *c;
 	const char *algo_name = "sha256";
 	u_int presskey_len = 0;
 	int abort = 0;
@@ -89,6 +90,14 @@ static int passwd_abort_sha256(uint64_t etime)
 	if (sha_env_str == NULL)
 		sha_env_str = AUTOBOOT_STOP_STR_SHA256;
 
+	presskey = malloc_cache_aligned(MAX_DELAY_STOP_STR);
+	c = strstr(sha_env_str, ":");
+	if (c && (c - sha_env_str < MAX_DELAY_STOP_STR)) {
+		/* preload presskey with salt */
+		memcpy(presskey, sha_env_str, c - sha_env_str);
+		presskey_len = c - sha_env_str;
+		sha_env_str = c + 1;
+	}
 	/*
 	 * Generate the binary value from the environment hash value
 	 * so that we can compare this value with the computed hash
@@ -100,7 +109,6 @@ static int passwd_abort_sha256(uint64_t etime)
 		return 0;
 	}
 
-	presskey = malloc_cache_aligned(MAX_DELAY_STOP_STR);
 	sha = malloc_cache_aligned(SHA256_SUM_LEN);
 	size = SHA256_SUM_LEN;
 	/*
-- 
1.8.3.1

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