wpa_supplicant: Support for mbedtls tls handshake

Add support for mbedtls based tls handshake, this removes
dependency from internal implementation of EAP client.

components/wpa_supplicant/src/crypto/sha256-prf.c

@@ -0,0 +1,108 @@
+/*
+ * SHA256-based PRF (IEEE 802.11r)
+ * Copyright (c) 2003-2016, Jouni Malinen <j@w1.fi>
+ *
+ * This software may be distributed under the terms of the BSD license.
+ * See README for more details.
+ */
+
+#include "utils/includes.h"
+
+#include "utils/common.h"
+#include "sha256.h"
+#include "crypto.h"
+
+
+/**
+ * sha256_prf - SHA256-based Pseudo-Random Function (IEEE 802.11r, 8.5.1.5.2)
+ * @key: Key for PRF
+ * @key_len: Length of the key in bytes
+ * @label: A unique label for each purpose of the PRF
+ * @data: Extra data to bind into the key
+ * @data_len: Length of the data
+ * @buf: Buffer for the generated pseudo-random key
+ * @buf_len: Number of bytes of key to generate
+ * Returns: 0 on success, -1 on failure
+ *
+ * This function is used to derive new, cryptographically separate keys from a
+ * given key.
+ */
+int sha256_prf(const u8 *key, size_t key_len, const char *label,
+		const u8 *data, size_t data_len, u8 *buf, size_t buf_len)
+{
+	return sha256_prf_bits(key, key_len, label, data, data_len, buf,
+			       buf_len * 8);
+}
+
+
+/**
+ * sha256_prf_bits - IEEE Std 802.11-2012, 11.6.1.7.2 Key derivation function
+ * @key: Key for KDF
+ * @key_len: Length of the key in bytes
+ * @label: A unique label for each purpose of the PRF
+ * @data: Extra data to bind into the key
+ * @data_len: Length of the data
+ * @buf: Buffer for the generated pseudo-random key
+ * @buf_len: Number of bits of key to generate
+ * Returns: 0 on success, -1 on failure
+ *
+ * This function is used to derive new, cryptographically separate keys from a
+ * given key. If the requested buf_len is not divisible by eight, the least
+ * significant 1-7 bits of the last octet in the output are not part of the
+ * requested output.
+ */
+int sha256_prf_bits(const u8 *key, size_t key_len, const char *label,
+		    const u8 *data, size_t data_len, u8 *buf,
+		    size_t buf_len_bits)
+{
+	u16 counter = 1;
+	size_t pos, plen;
+	u8 hash[SHA256_MAC_LEN];
+	const u8 *addr[4];
+	size_t len[4];
+	u8 counter_le[2], length_le[2];
+	size_t buf_len = (buf_len_bits + 7) / 8;
+
+	addr[0] = counter_le;
+	len[0] = 2;
+	addr[1] = (u8 *) label;
+	len[1] = os_strlen(label);
+	addr[2] = data;
+	len[2] = data_len;
+	addr[3] = length_le;
+	len[3] = sizeof(length_le);
+
+	WPA_PUT_LE16(length_le, buf_len_bits);
+	pos = 0;
+	while (pos < buf_len) {
+		plen = buf_len - pos;
+		WPA_PUT_LE16(counter_le, counter);
+		if (plen >= SHA256_MAC_LEN) {
+			if (hmac_sha256_vector(key, key_len, 4, addr, len,
+					       &buf[pos]) < 0)
+				return -1;
+			pos += SHA256_MAC_LEN;
+		} else {
+			if (hmac_sha256_vector(key, key_len, 4, addr, len,
+					       hash) < 0)
+				return -1;
+			os_memcpy(&buf[pos], hash, plen);
+			pos += plen;
+			break;
+		}
+		counter++;
+	}
+
+	/*
+	 * Mask out unused bits in the last octet if it does not use all the
+	 * bits.
+	 */
+	if (buf_len_bits % 8) {
+		u8 mask = 0xff << (8 - buf_len_bits % 8);
+		buf[pos - 1] &= mask;
+	}
+
+	os_memset(hash, 0, sizeof(hash));
+
+	return 0;
+}