Revert "linux: TLS PSK derivation fixes"

This reverts commit 3435511.

The info string now is '<size><size>tls13 HostNQN <size><hostnqn>' instead of
'<size>tls13 HostNQN <hostnqn>'.

Signed-off-by: Daniel Wagner <[email protected]>

Author: igaw

src/nvme/linux.c

@@ -618,46 +618,6 @@ static DEFINE_CLEANUP_FUNC(
 	cleanup_evp_pkey_ctx, EVP_PKEY_CTX *, EVP_PKEY_CTX_free)
 #define _cleanup_evp_pkey_ctx_ __cleanup__(cleanup_evp_pkey_ctx)
 
-/*
- * hkdf_info_printf()
- *
- * Helper function to append variable length label and context to an HkdfLabel
- *
- * RFC 8446 (TLS 1.3) Section 7.1 defines the HKDF-Expand-Label function as a
- * specialization of the HKDF-Expand function (RFC 5869), where the info
- * parameter is structured as an HkdfLabel.
- *
- * An HkdfLabel structure includes two variable length vectors (label and
- * context) which must be preceded by their content length as per RFC 8446
- * Section 3.4 (and not NUL terminated as per Section 7.1). Additionally,
- * HkdfLabel.label must begin with "tls13 "
- *
- * Returns the number of bytes appended to the HKDF info buffer, or -1 on an
- * error.
- */
-__attribute__((format(printf, 2, 3)))
-static int hkdf_info_printf(EVP_PKEY_CTX *ctx, char *fmt, ...)
-{
-	_cleanup_free_ char *str = NULL;
-	va_list myargs;
-	uint8_t len;
-	int ret;
-
-	va_start(myargs, fmt);
-	ret = vasprintf(&str, fmt, myargs);
-	va_end(myargs);
-	if (ret < 0)
-		return ret;
-	if (ret > 255)
-		return -1;
-	len = ret;
-	if (EVP_PKEY_CTX_add1_hkdf_info(ctx, (unsigned char *)&len, 1) <= 0)
-		return -1;
-	if (EVP_PKEY_CTX_add1_hkdf_info(ctx, (unsigned char *)str, len) <= 0)
-		return -1;
-	return (ret + 1);
-}
-
 /*
  * derive_retained_key()
  *
@@ -692,7 +652,7 @@ static int derive_retained_key(int hmac, const char *hostnqn,
 			       size_t key_len)
 {
 	_cleanup_evp_pkey_ctx_ EVP_PKEY_CTX *ctx = NULL;
-	uint16_t length = htons(key_len & 0xFFFF);
+	uint16_t length = key_len & 0xFFFF;
 	const EVP_MD *md;
 	size_t hmac_len;
 
@@ -730,11 +690,18 @@ static int derive_retained_key(int hmac, const char *hostnqn,
 		errno = ENOKEY;
 		return -1;
 	}
-	if (hkdf_info_printf(ctx, "tls13 HostNQN") <= 0) {
+	if (EVP_PKEY_CTX_add1_hkdf_info(ctx,
+			(const unsigned char *)"tls13 ", 6) <= 0) {
 		errno = ENOKEY;
 		return -1;
 	}
-	if (hkdf_info_printf(ctx, "%s", hostnqn) <= 0) {
+	if (EVP_PKEY_CTX_add1_hkdf_info(ctx,
+			(const unsigned char *)"HostNQN", 7) <= 0) {
+		errno = ENOKEY;
+		return -1;
+	}
+	if (EVP_PKEY_CTX_add1_hkdf_info(ctx,
+			(const unsigned char *)hostnqn, strlen(hostnqn)) <= 0) {
 		errno = ENOKEY;
 		return -1;
 	}
@@ -769,13 +736,12 @@ static int derive_retained_key(int hmac, const char *hostnqn,
  *
  * and the value '0' is invalid here.
  */
-
 static int derive_tls_key(int version, unsigned char cipher,
 			  const char *context, unsigned char *retained,
 			  unsigned char *psk, size_t key_len)
 {
 	_cleanup_evp_pkey_ctx_ EVP_PKEY_CTX *ctx = NULL;
-	uint16_t length = htons(key_len & 0xFFFF);
+	uint16_t length = key_len & 0xFFFF;
 	const EVP_MD *md;
 	size_t hmac_len;
 
@@ -808,24 +774,30 @@ static int derive_tls_key(int version, unsigned char cipher,
 		errno = ENOKEY;
 		return -1;
 	}
-	if (hkdf_info_printf(ctx, "tls13 nvme-tls-psk") <= 0) {
+	if (EVP_PKEY_CTX_add1_hkdf_info(ctx,
+			(const unsigned char *)"tls13 ", 6) <= 0) {
 		errno = ENOKEY;
 		return -1;
 	}
-	switch (version) {
-	case 0:
-		if (hkdf_info_printf(ctx, "%s", context) <= 0) {
-			errno = ENOKEY;
-			return -1;
-		}
-		break;
-	case 1:
-		if (hkdf_info_printf(ctx, "%02d %s", cipher, context) <= 0) {
+	if (EVP_PKEY_CTX_add1_hkdf_info(ctx,
+			(const unsigned char *)"nvme-tls-psk", 12) <= 0) {
+		errno = ENOKEY;
+		return -1;
+	}
+	if (version == 1) {
+		char hash_str[5];
+
+		sprintf(hash_str, "%02d ", cipher);
+		if (EVP_PKEY_CTX_add1_hkdf_info(ctx,
+				(const unsigned char *)hash_str,
+				strlen(hash_str)) <= 0) {
 			errno = ENOKEY;
 			return -1;
 		}
-		break;
-	default:
+	}
+	if (EVP_PKEY_CTX_add1_hkdf_info(ctx,
+			(const unsigned char *)context,
+			strlen(context)) <= 0) {
 		errno = ENOKEY;
 		return -1;
 	}