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-rw-r--r--src/methods/composed_gmac/composed_gmac.c317
1 files changed, 317 insertions, 0 deletions
diff --git a/src/methods/composed_gmac/composed_gmac.c b/src/methods/composed_gmac/composed_gmac.c
new file mode 100644
index 0000000..b63089f
--- /dev/null
+++ b/src/methods/composed_gmac/composed_gmac.c
@@ -0,0 +1,317 @@
+/*
+ Copyright (c) 2012-2013, 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.
+*/
+
+
+#include "../../fastd.h"
+#include "../common.h"
+
+
+static const fastd_block128_t ZERO_BLOCK = {};
+
+struct fastd_method_session_state {
+ fastd_method_common_t common;
+
+ const fastd_cipher_t *cipher;
+ const fastd_cipher_context_t *cipher_ctx;
+ fastd_cipher_state_t *cipher_state;
+
+ const fastd_cipher_t *gmac_cipher;
+ const fastd_cipher_context_t *gmac_cipher_ctx;
+ fastd_cipher_state_t *gmac_cipher_state;
+
+ const fastd_mac_t *ghash;
+ const fastd_mac_context_t *ghash_ctx;
+ fastd_mac_state_t *ghash_state;
+};
+
+
+static bool cipher_get(fastd_context_t *ctx, const char *name, const fastd_cipher_t **cipher, const fastd_cipher_context_t **cctx, const fastd_cipher_t **gmac_cipher, const fastd_cipher_context_t **gmac_cctx) {
+ if (!fastd_mac_available("ghash"))
+ return false;
+
+ size_t len = strlen(name);
+
+ if (len < 5)
+ return false;
+
+ if (strcmp(name+len-5, "-gmac"))
+ return false;
+
+ char cipher_name[len];
+ memcpy(cipher_name, name, len-4);
+ strncpy(cipher_name+len-4, "ctr", 4);
+
+ char *gmac_cipher_name = strchr(cipher_name, '+');
+
+ if (!gmac_cipher_name)
+ return false;
+
+ *gmac_cipher_name = 0;
+ gmac_cipher_name++;
+
+ if (ctx) {
+ *cipher = fastd_cipher_get_by_name(ctx, cipher_name, cctx);
+ *gmac_cipher = fastd_cipher_get_by_name(ctx, gmac_cipher_name, gmac_cctx);
+ return *cipher && *gmac_cipher;
+ }
+ else {
+ return fastd_cipher_available(cipher_name) && fastd_cipher_available(gmac_cipher_name);
+ }
+}
+
+
+static bool method_provides(const char *name) {
+ return cipher_get(NULL, name, NULL, NULL, NULL, NULL);
+}
+
+static size_t method_key_length(fastd_context_t *ctx, const char *name) {
+ const fastd_cipher_t *cipher = NULL;
+ const fastd_cipher_context_t *cctx;
+
+ const fastd_cipher_t *gmac_cipher = NULL;
+ const fastd_cipher_context_t *gmac_cctx;
+
+ if (!cipher_get(ctx, name, &cipher, &cctx, &gmac_cipher, &gmac_cctx))
+ exit_bug(ctx, "composed-gmac: can't get cipher key length");
+
+ return cipher->key_length + gmac_cipher->key_length;
+}
+
+static fastd_method_session_state_t* method_session_init(fastd_context_t *ctx, const char *name, const uint8_t *secret, bool initiator) {
+ fastd_method_session_state_t *session = malloc(sizeof(fastd_method_session_state_t));
+
+ fastd_method_common_init(ctx, &session->common, initiator);
+
+ if (!cipher_get(ctx, name, &session->cipher, &session->cipher_ctx, &session->gmac_cipher, &session->gmac_cipher_ctx))
+ exit_bug(ctx, "composed-gmac: can't instanciate cipher");
+
+ session->cipher_state = session->cipher->init_state(ctx, session->cipher_ctx, secret);
+ if (session->cipher->iv_length && session->cipher->iv_length <= COMMON_NONCEBYTES)
+ exit_bug(ctx, "composed-gmac: iv_length to small");
+
+ session->gmac_cipher_state = session->gmac_cipher->init_state(ctx, session->gmac_cipher_ctx, secret + session->cipher->key_length);
+ if (session->gmac_cipher->iv_length <= COMMON_NONCEBYTES)
+ exit_bug(ctx, "composed-gmac: GMAC cipher iv_length to small");
+
+ fastd_block128_t H;
+
+ uint8_t zeroiv[session->gmac_cipher->iv_length];
+ memset(zeroiv, 0, session->gmac_cipher->iv_length);
+
+ session->gmac_cipher->crypt(ctx, session->gmac_cipher_state, &H, &ZERO_BLOCK, sizeof(fastd_block128_t), zeroiv);
+
+ session->ghash = fastd_mac_get_by_name(ctx, "ghash", &session->ghash_ctx);
+ if (!session->ghash)
+ exit_bug(ctx, "composed-gmac: can't instanciate ghash mac");
+
+ session->ghash_state = session->ghash->init_state(ctx, session->ghash_ctx, H.b);
+
+ return session;
+}
+
+static bool method_session_is_valid(fastd_context_t *ctx, fastd_method_session_state_t *session) {
+ return (session && fastd_method_session_common_is_valid(ctx, &session->common));
+}
+
+static bool method_session_is_initiator(fastd_context_t *ctx UNUSED, fastd_method_session_state_t *session) {
+ return fastd_method_session_common_is_initiator(&session->common);
+}
+
+static bool method_session_want_refresh(fastd_context_t *ctx, fastd_method_session_state_t *session) {
+ return fastd_method_session_common_want_refresh(ctx, &session->common);
+}
+
+static void method_session_superseded(fastd_context_t *ctx, fastd_method_session_state_t *session) {
+ fastd_method_session_common_superseded(ctx, &session->common);
+}
+
+static void method_session_free(fastd_context_t *ctx, fastd_method_session_state_t *session) {
+ if (session) {
+ session->cipher->free_state(ctx, session->cipher_state);
+ session->gmac_cipher->free_state(ctx, session->gmac_cipher_state);
+ session->ghash->free_state(ctx, session->ghash_state);
+
+ free(session);
+ }
+}
+
+static inline void put_size(fastd_block128_t *out, size_t len) {
+ memset(out, 0, sizeof(fastd_block128_t));
+ out->b[3] = len >> 29;
+ out->b[4] = len >> 21;
+ out->b[5] = len >> 13;
+ out->b[6] = len >> 5;
+ out->b[7] = len << 3;
+}
+
+static bool method_encrypt(fastd_context_t *ctx, 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(ctx, sizeof(fastd_block128_t)+in.len, alignto(COMMON_HEADBYTES, 16), sizeof(fastd_block128_t)+tail_len);
+
+ if (tail_len)
+ memset(in.data+in.len, 0, tail_len);
+
+ int n_blocks = block_count(in.len, sizeof(fastd_block128_t));
+
+ fastd_block128_t *inblocks = in.data;
+ fastd_block128_t *outblocks = out->data;
+ fastd_block128_t sig;
+
+ uint8_t gmac_nonce[session->gmac_cipher->iv_length];
+ memset(gmac_nonce, 0, session->gmac_cipher->iv_length);
+ memcpy(gmac_nonce, session->common.send_nonce, COMMON_NONCEBYTES);
+ gmac_nonce[session->gmac_cipher->iv_length-1] = 1;
+
+ bool ok = session->gmac_cipher->crypt(ctx, session->gmac_cipher_state, outblocks, &ZERO_BLOCK, sizeof(fastd_block128_t), gmac_nonce);
+
+ if (ok) {
+ uint8_t nonce[session->cipher->iv_length];
+ if (session->cipher->iv_length) {
+ memset(nonce, 0, session->cipher->iv_length);
+ memcpy(nonce, session->common.send_nonce, COMMON_NONCEBYTES);
+ nonce[session->cipher->iv_length-1] = 1;
+ }
+
+ ok = session->cipher->crypt(ctx, session->cipher_state, outblocks+1, inblocks, n_blocks*sizeof(fastd_block128_t), nonce);
+ }
+
+ if (ok) {
+ if (tail_len)
+ memset(out->data+out->len, 0, tail_len);
+
+ put_size(&outblocks[n_blocks+1], in.len);
+
+ ok = session->ghash->hash(ctx, session->ghash_state, &sig, outblocks+1, n_blocks+1);
+ }
+
+ if (!ok) {
+ fastd_buffer_free(*out);
+ return false;
+ }
+
+ xor_a(&outblocks[0], &sig);
+
+ fastd_buffer_free(in);
+
+ fastd_buffer_pull_head(ctx, out, COMMON_HEADBYTES);
+
+ memcpy(out->data, session->common.send_nonce, COMMON_NONCEBYTES);
+ fastd_method_increment_nonce(&session->common);
+
+ ((uint8_t*)out->data)[COMMON_NONCEBYTES] = 0; /* flags */
+
+ return true;
+}
+
+static bool method_decrypt(fastd_context_t *ctx, 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(ctx, session))
+ return false;
+
+ const uint8_t *common_nonce = in.data;
+
+ if (common_nonce[COMMON_NONCEBYTES]) /* flags */
+ return false;
+
+ int64_t age;
+ if (!fastd_method_is_nonce_valid(ctx, &session->common, common_nonce, &age))
+ return false;
+
+ uint8_t gmac_nonce[session->gmac_cipher->iv_length];
+ memset(gmac_nonce, 0, session->gmac_cipher->iv_length);
+ memcpy(gmac_nonce, common_nonce, COMMON_NONCEBYTES);
+ gmac_nonce[session->gmac_cipher->iv_length-1] = 1;
+
+ uint8_t nonce[session->cipher->iv_length];
+ if (session->cipher->iv_length) {
+ memset(nonce, 0, session->cipher->iv_length);
+ memcpy(nonce, common_nonce, COMMON_NONCEBYTES);
+ nonce[session->cipher->iv_length-1] = 1;
+ }
+
+ fastd_buffer_push_head(ctx, &in, COMMON_HEADBYTES);
+
+ size_t tail_len = alignto(in.len, sizeof(fastd_block128_t))-in.len;
+ *out = fastd_buffer_alloc(ctx, in.len, 0, tail_len);
+
+ int n_blocks = block_count(in.len, sizeof(fastd_block128_t));
+
+ fastd_block128_t *inblocks = in.data;
+ fastd_block128_t *outblocks = out->data;
+ fastd_block128_t sig;
+
+ bool ok = session->gmac_cipher->crypt(ctx, session->gmac_cipher_state, outblocks, inblocks, sizeof(fastd_block128_t), gmac_nonce);
+
+ if (ok)
+ ok = session->cipher->crypt(ctx, session->cipher_state, outblocks+1, inblocks+1, (n_blocks-1)*sizeof(fastd_block128_t), nonce);
+
+ if (ok) {
+ if (tail_len)
+ memset(in.data+in.len, 0, tail_len);
+
+ put_size(&inblocks[n_blocks], in.len-sizeof(fastd_block128_t));
+
+ ok = session->ghash->hash(ctx, session->ghash_state, &sig, inblocks+1, n_blocks);
+ }
+
+ if (!ok || memcmp(&sig, &outblocks[0], sizeof(fastd_block128_t)) != 0) {
+ fastd_buffer_free(*out);
+ return false;
+ }
+
+ fastd_buffer_push_head(ctx, out, sizeof(fastd_block128_t));
+
+ if (!fastd_method_reorder_check(ctx, peer, &session->common, common_nonce, age)) {
+ fastd_buffer_free(*out);
+ *out = fastd_buffer_alloc(ctx, 0, 0, 0);
+ }
+
+ fastd_buffer_free(in);
+
+ return true;
+}
+
+const fastd_method_t fastd_method_composed_gmac = {
+ .provides = method_provides,
+
+ .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 = 2*sizeof(fastd_block128_t)-1,
+
+ .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,
+};