set errno = EINVAL for invalid salts and hashes in most functions.

remember to set EACCES in bcrypt_checkpass for hash differences.
the higher level crypt_checkpass function will reset errno to EACCES in
all cases, which is probably the right behavior, but this change gives code
working with the lower level functions the correct errno if they care.

src/lib/libc/crypt/bcrypt.c

@@ -1,4 +1,4 @@
-/*	$OpenBSD: bcrypt.c,v 1.48 2015/01/05 13:10:10 tedu Exp $	*/
+/*	$OpenBSD: bcrypt.c,v 1.49 2015/01/07 15:46:23 tedu Exp $	*/
 
 /*
  * Copyright (c) 2014 Ted Unangst <tedu@openbsd.org>
@@ -65,8 +65,10 @@ bcrypt_initsalt(int log_rounds, uint8_t *salt, size_t saltbuflen)
 {
 	uint8_t csalt[BCRYPT_MAXSALT];
 
-	if (saltbuflen < BCRYPT_SALTSPACE)
+	if (saltbuflen < BCRYPT_SALTSPACE) {
+		errno = EINVAL;
 		return -1;
+	}
 
 	arc4random_buf(csalt, sizeof(csalt));
 
@@ -98,15 +100,15 @@ bcrypt_hashpass(const char *key, const char *salt, char *encrypted,
 	u_int32_t cdata[BCRYPT_BLOCKS];
 
 	if (encryptedlen < BCRYPT_HASHSPACE)
-		return -1;
+		goto inval;
 
 	/* Check and discard "$" identifier */
 	if (salt[0] != '$')
-		return -1;
+		goto inval;
 	salt += 1;
 
 	if (salt[0] != BCRYPT_VERSION)
-		return -1;
+		goto inval;
 
 	/* Check for minor versions */
 	switch ((minor = salt[1])) {
@@ -124,20 +126,20 @@ bcrypt_hashpass(const char *key, const char *salt, char *encrypted,
 		key_len++; /* include the NUL */
 		break;
 	default:
-		 return -1;
+		 goto inval;
 	}
 	if (salt[2] != '$')
-		return -1;
+		goto inval;
 	/* Discard version + "$" identifier */
 	salt += 3;
 
 	/* Check and parse num rounds */
 	if (!isdigit((unsigned char)salt[0]) ||
 	    !isdigit((unsigned char)salt[1]) || salt[2] != '$')
-		return -1;
+		goto inval;
 	logr = atoi(salt);
 	if (logr < BCRYPT_MINLOGROUNDS || logr > 31)
-		return -1;
+		goto inval;
 	/* Computer power doesn't increase linearly, 2^x should be fine */
 	rounds = 1U << logr;
 
@@ -145,11 +147,11 @@ bcrypt_hashpass(const char *key, const char *salt, char *encrypted,
 	salt += 3;
 
 	if (strlen(salt) * 3 / 4 < BCRYPT_MAXSALT)
-		return -1;
+		goto inval;
 
 	/* We dont want the base64 salt but the raw data */
 	if (decode_base64(csalt, BCRYPT_MAXSALT, salt))
-		return -1;
+		goto inval;
 	salt_len = BCRYPT_MAXSALT;
 
 	/* Setting up S-Boxes and Subkeys */
@@ -189,6 +191,10 @@ bcrypt_hashpass(const char *key, const char *salt, char *encrypted,
 	explicit_bzero(csalt, sizeof(csalt));
 	explicit_bzero(cdata, sizeof(cdata));
 	return 0;
+
+inval:
+	errno = EINVAL;
+	return -1;
 }
 
 /*
@@ -217,8 +223,10 @@ bcrypt_checkpass(const char *pass, const char *goodhash)
 	if (bcrypt_hashpass(pass, goodhash, hash, sizeof(hash)) != 0)
 		return -1;
 	if (strlen(hash) != strlen(goodhash) ||
-	    timingsafe_bcmp(hash, goodhash, strlen(goodhash)) != 0)
+	    timingsafe_bcmp(hash, goodhash, strlen(goodhash)) != 0) {
+		errno = EACCES;
 		return -1;
+	}
 
 	explicit_bzero(hash, sizeof(hash));
 	return 0;