[PATCH 7/8] password: add pbkdf2 support

[Jean-Christophe PLAGNIOL-VILLARD]

We will use "barebox_password" as salt and 10000 round to generate a
64 bytes key.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj at jcrosoft.com>
---
 common/Kconfig    |  4 +++
 common/password.c | 79 +++++++++++++++++++++++++++++++++++--------------------
 2 files changed, 55 insertions(+), 28 deletions(-)

diff --git a/common/Kconfig b/common/Kconfig
index 96ace6b..ad8a596 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -453,6 +453,10 @@ config PASSWD_SUM_SHA512
 	bool "SHA512"
 	select SHA512
 
+config PASSWD_CRYPTO_PBKDF2
+	bool "PBKDF2"
+	select CRYPTO_PBKDF2
+
 endchoice
 
 endif
diff --git a/common/password.c b/common/password.c
index 6ecf717..0e1db61 100644
--- a/common/password.c
+++ b/common/password.c
@@ -26,6 +26,7 @@
 #include <xfuncs.h>
 #include <clock.h>
 #include <generated/passwd.h>
+#include <crypto/pbkdf2.h>
 
 #if defined(CONFIG_PASSWD_SUM_MD5)
 #define PASSWD_SUM "md5"
@@ -35,8 +36,14 @@
 #define PASSWD_SUM "sha256"
 #elif defined(CONFIG_PASSWD_SUM_SHA512)
 #define PASSWD_SUM "sha512"
+#else
+#define PASSWD_SUM	NULL
 #endif
 
+#define PBKDF2_SALT	"barebox_password"
+#define PBKDF2_LENGTH	64
+#define PBKDF2_COUNT	10000
+
 int password(unsigned char *passwd, size_t length, int flags, int timeout)
 {
 	unsigned char *buf = passwd;
@@ -277,45 +284,50 @@ EXPORT_SYMBOL(write_env_passwd);
 
 static int __check_passwd(unsigned char* passwd, size_t length, int std)
 {
-	struct digest *d;
+	struct digest *d = NULL;
 	unsigned char *passwd1_sum;
 	unsigned char *passwd2_sum;
 	int ret = 0;
+	int hash_len;
 
-	d = digest_alloc(PASSWD_SUM);
+	if (IS_ENABLED(CONFIG_PASSWD_CRYPTO_PBKDF2)) {
+		hash_len = PBKDF2_LENGTH;
+	} else {
+		d = digest_alloc(PASSWD_SUM);
 
-	passwd1_sum = calloc(digest_length(d), sizeof(unsigned char));
+		hash_len = digest_length(d);
+	}
 
+	passwd1_sum = calloc(hash_len * 2, sizeof(unsigned char));
 	if (!passwd1_sum)
 		return -ENOMEM;
 
-	passwd2_sum = calloc(digest_length(d), sizeof(unsigned char));
-
-	if (!passwd2_sum) {
-		ret = -ENOMEM;
-		goto err1;
-	}
+	passwd2_sum = passwd1_sum + hash_len;
 
-	digest_init(d);
+	if (IS_ENABLED(CONFIG_PASSWD_CRYPTO_PBKDF2)) {
+		char *salt = PBKDF2_SALT;
 
-	digest_update(d, passwd, length);
+		ret = pkcs5_pbkdf2_hmac_sha1(passwd, length, salt, strlen(salt),
+					PBKDF2_COUNT, hash_len, passwd1_sum);
+	} else {
+		ret = digest_digest(d, passwd, length, passwd1_sum);
+	}
 
-	digest_final(d, passwd1_sum);
+	if (ret)
+		goto err;
 
 	if (std)
-		ret = read_env_passwd(passwd2_sum, digest_length(d));
+		ret = read_env_passwd(passwd2_sum, hash_len);
 	else
-		ret = read_default_passwd(passwd2_sum, digest_length(d));
+		ret = read_default_passwd(passwd2_sum, hash_len);
 
 	if (ret < 0)
-		goto err2;
+		goto err;
 
-	if (strncmp(passwd1_sum, passwd2_sum, digest_length(d)) == 0)
+	if (strncmp(passwd1_sum, passwd2_sum, hash_len) == 0)
 		ret = 1;
 
-err2:
-	free(passwd2_sum);
-err1:
+err:
 	free(passwd1_sum);
 	digest_free(d);
 
@@ -346,25 +358,36 @@ int check_passwd(unsigned char* passwd, size_t length)
 
 int set_env_passwd(unsigned char* passwd, size_t length)
 {
-	struct digest *d;
+	struct digest *d = NULL;
 	unsigned char *passwd_sum;
-	int ret;
+	int ret, hash_len;
 
-	d = digest_alloc(PASSWD_SUM);
+	if (IS_ENABLED(CONFIG_PASSWD_CRYPTO_PBKDF2)) {
+		hash_len = PBKDF2_LENGTH;
+	} else {
+		d = digest_alloc(PASSWD_SUM);
 
-	passwd_sum = calloc(digest_length(d), sizeof(unsigned char));
+		hash_len = digest_length(d);
+	}
 
+	passwd_sum = calloc(hash_len, sizeof(unsigned char));
 	if (!passwd_sum)
 		return -ENOMEM;
 
-	digest_init(d);
+	if (IS_ENABLED(CONFIG_PASSWD_CRYPTO_PBKDF2)) {
+		char *salt = PBKDF2_SALT;
 
-	digest_update(d, passwd, length);
-
-	digest_final(d, passwd_sum);
+		ret = pkcs5_pbkdf2_hmac_sha1(passwd, length, salt, strlen(salt),
+				       PBKDF2_COUNT, hash_len, passwd_sum);
+	} else {
+		ret = digest_digest(d, passwd, length, passwd_sum);
+	}
+	if (ret)
+		goto err;
 
-	ret = write_env_passwd(passwd_sum, digest_length(d));
+	ret = write_env_passwd(passwd_sum, hash_len);
 
+err:
 	free(passwd_sum);
 
 	return ret;
-- 
2.1.4