Experimental HMAC-SHA1 implementation

This adds experimental support for <cipher>+hmac-sha1 methods. It currently
depends on OpenSSL and is not yet ready for production use.

2 files changed, 263 insertions, 0 deletions

diff --git a/src/methods/generic_hmac_sha1/CMakeLists.txt b/src/methods/generic_hmac_sha1/CMakeLists.txt
new file mode 100644
index 0000000..b70bc1d
--- /dev/null
+++ b/src/methods/generic_hmac_sha1/CMakeLists.txt
@@ -0,0 +1,4 @@
+fastd_method(generic-hmac-sha1
+  generic_hmac_sha1.c
+)
+fastd_method_link_libraries(generic-hmac-sha1 method_common)
diff --git a/src/methods/generic_hmac_sha1/generic_hmac_sha1.c b/src/methods/generic_hmac_sha1/generic_hmac_sha1.c
new file mode 100644
index 0000000..530abe3
--- /dev/null
+++ b/src/methods/generic_hmac_sha1/generic_hmac_sha1.c
@@ -0,0 +1,259 @@
+/*
+  Copyright (c) 2012-2014, Matthias Schiffer <mschiffer@universe-factory.net>
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are met:
+
+    1. Redistributions of source code must retain the above copyright notice,
+       this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright notice,
+       this list of conditions and the following disclaimer in the documentation
+       and/or other materials provided with the distribution.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/**
+   \file
+
+   generic-gmac method provider
+
+   generic-gmac can combine any stream cipher with the GMAC authentication.
+*/
+
+
+#include "../../crypto.h"
+#include "../../method.h"
+#include "../common.h"
+
+
+/** A specific method provided by this provider */
+struct fastd_method {
+	const fastd_cipher_info_t *cipher_info;		/**< The cipher used */
+	const fastd_mac_info_t *hmac_sha1_info;		/**< HMAC-SHA1 */
+};
+
+/** The method-specific session state */
+struct fastd_method_session_state {
+	fastd_method_common_t common;			/**< The common method state */
+
+	const fastd_method_t *method;			/**< The specific method used */
+
+	const fastd_cipher_t *cipher;			/**< The cipher implementation used */
+	fastd_cipher_state_t *cipher_state;		/**< The cipher state */
+
+	const fastd_mac_t *hmac_sha1;			/**< The HMAC-SHA1 implementation */
+	fastd_mac_state_t *hmac_sha1_state;		/**< The HMAC-SHA1 state */
+};
+
+
+/** Instanciates a method using a name of the pattern "<cipher>+hmac-sha1" */
+static bool method_create_by_name(const char *name, fastd_method_t **method) {
+	fastd_method_t m;
+
+	m.hmac_sha1_info = fastd_mac_info_get_by_name("hmac-sha1");
+	if (!m.hmac_sha1_info)
+		return false;
+
+	size_t len = strlen(name);
+	if (len < 10)
+		return false;
+
+	if (strcmp(name+len-10, "+hmac-sha1"))
+		return false;
+
+	char cipher_name[len-9];
+	memcpy(cipher_name, name, len-10);
+	cipher_name[len-10] = 0;
+
+	m.cipher_info = fastd_cipher_info_get_by_name(cipher_name);
+	if (!m.cipher_info)
+		return false;
+
+	*method = fastd_new(fastd_method_t);
+	**method = m;
+
+	return true;
+}
+
+/** Frees a method */
+static void method_destroy(fastd_method_t *method) {
+	free(method);
+}
+
+/** Returns the key length used by a method */
+static size_t method_key_length(const fastd_method_t *method) {
+	return method->cipher_info->key_length + method->hmac_sha1_info->key_length;
+}
+
+/** Initializes a session */
+static fastd_method_session_state_t * method_session_init(const fastd_method_t *method, const uint8_t *secret, bool initiator) {
+	fastd_method_session_state_t *session = fastd_new(fastd_method_session_state_t);
+
+	fastd_method_common_init(&session->common, initiator);
+	session->method = method;
+
+	session->cipher = fastd_cipher_get(method->cipher_info);
+	session->cipher_state = session->cipher->init(secret);
+
+	session->hmac_sha1 = fastd_mac_get(method->hmac_sha1_info);
+	session->hmac_sha1_state = session->hmac_sha1->init(secret + method->cipher_info->key_length);
+
+	return session;
+}
+
+/** Checks if the session is currently valid */
+static bool method_session_is_valid(fastd_method_session_state_t *session) {
+	return (session && fastd_method_session_common_is_valid(&session->common));
+}
+
+/** Checks if this side is the initator of the session */
+static bool method_session_is_initiator(fastd_method_session_state_t *session) {
+	return fastd_method_session_common_is_initiator(&session->common);
+}
+
+/** Checks if the session should be refreshed */
+static bool method_session_want_refresh(fastd_method_session_state_t *session) {
+	return fastd_method_session_common_want_refresh(&session->common);
+}
+
+/** Marks the session as superseded */
+static void method_session_superseded(fastd_method_session_state_t *session) {
+	fastd_method_session_common_superseded(&session->common);
+}
+
+/** Frees the session state */
+static void method_session_free(fastd_method_session_state_t *session) {
+	if (session) {
+		session->cipher->free(session->cipher_state);
+		session->hmac_sha1->free(session->hmac_sha1_state);
+
+		free(session);
+	}
+}
+
+
+/** Encrypts and authenticates a packet */
+static bool method_encrypt(fastd_peer_t *peer UNUSED, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in) {
+	size_t tail_len = alignto(in.len, sizeof(fastd_block128_t))-in.len;
+	*out = fastd_buffer_alloc(in.len + sizeof(fastd_block128_t), alignto(COMMON_HEADBYTES, 16), sizeof(fastd_block128_t)+tail_len);
+
+	if (tail_len)
+		memset(in.data+in.len, 0, tail_len);
+
+	uint8_t nonce[session->method->cipher_info->iv_length] __attribute__((aligned(8)));
+	fastd_method_expand_nonce(nonce, session->common.send_nonce, sizeof(nonce));
+
+	fastd_block128_t *outblocks = out->data;
+	fastd_block128_t tag;
+
+	bool ok = session->cipher->crypt(session->cipher_state, outblocks+1, in.data, in.len, nonce);
+
+	if (ok) {
+		fastd_method_expand_nonce(out->data, session->common.send_nonce, sizeof(fastd_block128_t));
+		ok = session->hmac_sha1->digest(session->hmac_sha1_state, &tag, out->data, out->len);
+	}
+
+	if (!ok) {
+		fastd_buffer_free(*out);
+		return false;
+	}
+
+	outblocks[0] = tag;
+
+	fastd_buffer_free(in);
+
+	fastd_method_put_common_header(out, session->common.send_nonce, 0);
+	fastd_method_increment_nonce(&session->common);
+
+	return true;
+}
+
+/** Verifies and decrypts a packet */
+static bool method_decrypt(fastd_peer_t *peer, fastd_method_session_state_t *session, fastd_buffer_t *out, fastd_buffer_t in) {
+	if (in.len < COMMON_HEADBYTES+sizeof(fastd_block128_t))
+		return false;
+
+	if (!method_session_is_valid(session))
+		return false;
+
+	uint8_t in_nonce[COMMON_NONCEBYTES];
+	uint8_t flags;
+	int64_t age;
+	if (!fastd_method_handle_common_header(&session->common, &in, in_nonce, &flags, &age))
+		return false;
+
+	if (flags)
+		return false;
+
+	uint8_t nonce[session->method->cipher_info->iv_length] __attribute__((aligned(8)));
+	fastd_method_expand_nonce(nonce, in_nonce, sizeof(nonce));
+
+	fastd_block128_t *inblocks = in.data;
+	fastd_block128_t tag = inblocks[0], tag2;
+
+	fastd_method_expand_nonce(in.data, in_nonce, sizeof(fastd_block128_t));
+	bool ok = session->hmac_sha1->digest(session->hmac_sha1_state, &tag2, in.data, in.len);
+
+	if (ok && memcmp(&tag, &tag2, sizeof(fastd_block128_t)) != 0)
+		ok = false;
+
+	if (ok) {
+		size_t tail_len = alignto(in.len, sizeof(fastd_block128_t))-in.len;
+		*out = fastd_buffer_alloc(in.len - sizeof(fastd_block128_t), 0, tail_len);
+
+		ok = session->cipher->crypt(session->cipher_state, out->data, inblocks+1, in.len - sizeof(fastd_block128_t), nonce);
+
+		if (!ok)
+			fastd_buffer_free(*out);
+	}
+
+	if (!ok) {
+		inblocks[0] = tag;
+		return false;
+	}
+
+	fastd_buffer_free(in);
+
+	if (!fastd_method_reorder_check(peer, &session->common, in_nonce, age)) {
+		fastd_buffer_free(*out);
+		*out = fastd_buffer_alloc(0, 0, 0);
+	}
+
+	return true;
+}
+
+
+/** The generic-hmac-sha1 method provider */
+const fastd_method_provider_t fastd_method_generic_hmac_sha1 = {
+	.max_overhead = COMMON_HEADBYTES + sizeof(fastd_block128_t),
+	.min_encrypt_head_space = 0,
+	.min_decrypt_head_space = 0,
+	.min_encrypt_tail_space = sizeof(fastd_block128_t)-1,
+	.min_decrypt_tail_space = sizeof(fastd_block128_t)-1,
+
+	.create_by_name = method_create_by_name,
+	.destroy = method_destroy,
+
+	.key_length = method_key_length,
+
+	.session_init = method_session_init,
+	.session_is_valid = method_session_is_valid,
+	.session_is_initiator = method_session_is_initiator,
+	.session_want_refresh = method_session_want_refresh,
+	.session_superseded = method_session_superseded,
+	.session_free = method_session_free,
+
+	.encrypt = method_encrypt,
+	.decrypt = method_decrypt,
+};