Add internal HMAC-SHA512 implementation to fix NEED_SHA512 builds

Build configurations with CONFIG_TLS=internal and NEED_SHA512 failed due
to missing sha512.c file. Add that file even though this is not really
used in the currently available configuration combinations since DPP and
OWE are the only users of it and the internal crypto implementation
supports neither.

Signed-off-by: Jouni Malinen <j@w1.fi>

src/crypto/sha512.c

@@ -0,0 +1,104 @@
+/*
+ * SHA-512 hash implementation and interface functions
+ * Copyright (c) 2003-2018, Jouni Malinen <j@w1.fi>
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "includes.h"
+
+#include "common.h"
+#include "sha512.h"
+#include "crypto.h"
+
+
+/**
+ * hmac_sha512_vector - HMAC-SHA512 over data vector (RFC 2104)
+ * @key: Key for HMAC operations
+ * @key_len: Length of the key in bytes
+ * @num_elem: Number of elements in the data vector
+ * @addr: Pointers to the data areas
+ * @len: Lengths of the data blocks
+ * @mac: Buffer for the hash (64 bytes)
+ * Returns: 0 on success, -1 on failure
+ */
+int hmac_sha512_vector(const u8 *key, size_t key_len, size_t num_elem,
+		       const u8 *addr[], const size_t *len, u8 *mac)
+{
+	unsigned char k_pad[128]; /* padding - key XORd with ipad/opad */
+	unsigned char tk[64];
+	const u8 *_addr[6];
+	size_t _len[6], i;
+
+	if (num_elem > 5) {
+		/*
+		 * Fixed limit on the number of fragments to avoid having to
+		 * allocate memory (which could fail).
+		 */
+		return -1;
+	}
+
+	/* if key is longer than 128 bytes reset it to key = SHA512(key) */
+	if (key_len > 128) {
+		if (sha512_vector(1, &key, &key_len, tk) < 0)
+			return -1;
+		key = tk;
+		key_len = 64;
+	}
+
+	/* the HMAC_SHA512 transform looks like:
+	 *
+	 * SHA512(K XOR opad, SHA512(K XOR ipad, text))
+	 *
+	 * where K is an n byte key
+	 * ipad is the byte 0x36 repeated 128 times
+	 * opad is the byte 0x5c repeated 128 times
+	 * and text is the data being protected */
+
+	/* start out by storing key in ipad */
+	os_memset(k_pad, 0, sizeof(k_pad));
+	os_memcpy(k_pad, key, key_len);
+	/* XOR key with ipad values */
+	for (i = 0; i < 128; i++)
+		k_pad[i] ^= 0x36;
+
+	/* perform inner SHA512 */
+	_addr[0] = k_pad;
+	_len[0] = 128;
+	for (i = 0; i < num_elem; i++) {
+		_addr[i + 1] = addr[i];
+		_len[i + 1] = len[i];
+	}
+	if (sha512_vector(1 + num_elem, _addr, _len, mac) < 0)
+		return -1;
+
+	os_memset(k_pad, 0, sizeof(k_pad));
+	os_memcpy(k_pad, key, key_len);
+	/* XOR key with opad values */
+	for (i = 0; i < 128; i++)
+		k_pad[i] ^= 0x5c;
+
+	/* perform outer SHA512 */
+	_addr[0] = k_pad;
+	_len[0] = 128;
+	_addr[1] = mac;
+	_len[1] = SHA512_MAC_LEN;
+	return sha512_vector(2, _addr, _len, mac);
+}
+
+
+/**
+ * hmac_sha512 - HMAC-SHA512 over data buffer (RFC 2104)
+ * @key: Key for HMAC operations
+ * @key_len: Length of the key in bytes
+ * @data: Pointers to the data area
+ * @data_len: Length of the data area
+ * @mac: Buffer for the hash (64 bytes)
+ * Returns: 0 on success, -1 on failure
+ */
+int hmac_sha512(const u8 *key, size_t key_len, const u8 *data,
+		size_t data_len, u8 *mac)
+{
+	return hmac_sha512_vector(key, key_len, 1, &data, &data_len, mac);
+}