diff options
Diffstat (limited to 'src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c')
| -rw-r--r-- | src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c | 1014 |
1 files changed, 1014 insertions, 0 deletions
diff --git a/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c b/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c new file mode 100644 index 0000000..9fe1414 --- /dev/null +++ b/src/protocols/ec25519_fhmqvc/ec25519_fhmqvc.c @@ -0,0 +1,1014 @@ +/* + 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 <handshake.h> +#include <peer.h> +#include <sha256.h> + +#include <libuecc/ecc.h> + + +#define PUBLICKEYBYTES 32 +#define SECRETKEYBYTES 32 +#define HASHBYTES FASTD_SHA256_HASH_BYTES + + +#if HASHBYTES != FASTD_HMACSHA256_KEY_BYTES +#error bug: HASHBYTES != FASTD_HMACSHA256_KEY_BYTES +#endif + +#if HASHBYTES != SECRETKEYBYTES +#error bug: HASHBYTES != SECRETKEYBYTES +#endif + + +typedef ecc_int256_t __attribute__((aligned(4))) aligned_int256_t; + +typedef struct keypair { + ecc_int256_t secret; + aligned_int256_t public; +} keypair_t; + +struct fastd_protocol_config { + keypair_t key; +}; + +typedef struct handshake_key { + uint64_t serial; + struct timespec preferred_till; + struct timespec valid_till; + + /* keypair used as initiator */ + keypair_t key1; + + /* keypair used as responder */ + keypair_t key2; +} handshake_key_t; + +struct fastd_protocol_state { + handshake_key_t prev_handshake_key; + handshake_key_t handshake_key; +}; + +struct fastd_protocol_peer_config { + aligned_int256_t public_key; +}; + +typedef struct protocol_session { + struct timespec established; + + bool handshakes_cleaned; + bool refreshing; + + const fastd_method_t *method; + fastd_method_session_state_t *method_state; +} protocol_session_t; + +struct fastd_protocol_peer_state { + protocol_session_t old_session; + protocol_session_t session; + + uint64_t last_serial; + + /* handshake cache */ + uint64_t last_handshake_serial; + aligned_int256_t peer_handshake_key; + aligned_int256_t sigma; + fastd_sha256_t shared_handshake_key; +}; + + +#define RECORD_SENDER_KEY RECORD_PROTOCOL1 +#define RECORD_RECEIPIENT_KEY RECORD_PROTOCOL2 +#define RECORD_SENDER_HANDSHAKE_KEY RECORD_PROTOCOL3 +#define RECORD_RECEIPIENT_HANDSHAKE_KEY RECORD_PROTOCOL4 +#define RECORD_T RECORD_PROTOCOL5 + + +static void send_empty(fastd_context_t *ctx, fastd_peer_t *peer, protocol_session_t *session); + + +static inline bool read_key(uint8_t key[32], const char *hexkey) { + if ((strlen(hexkey) != 64) || (strspn(hexkey, "0123456789abcdefABCDEF") != 64)) + return false; + + int i; + for (i = 0; i < 32; i++) + sscanf(&hexkey[2*i], "%02hhx", &key[i]); + + return true; +} + +static inline bool is_handshake_key_valid(fastd_context_t *ctx, const handshake_key_t *handshake_key) { + return timespec_after(&handshake_key->valid_till, &ctx->now); +} + +static inline bool is_handshake_key_preferred(fastd_context_t *ctx, const handshake_key_t *handshake_key) { + return timespec_after(&handshake_key->preferred_till, &ctx->now); +} + +static inline bool is_session_valid(fastd_context_t *ctx, const protocol_session_t *session) { + return (session->method && session->method->session_is_valid(ctx, session->method_state)); +} + +static bool backoff(fastd_context_t *ctx, const fastd_peer_t *peer) { + return (peer->protocol_state && is_session_valid(ctx, &peer->protocol_state->session) + && timespec_diff(&ctx->now, &peer->protocol_state->session.established) < 15000); +} + +static inline void check_session_refresh(fastd_context_t *ctx, fastd_peer_t *peer) { + protocol_session_t *session = &peer->protocol_state->session; + + if (!session->refreshing && session->method->session_is_initiator(ctx, session->method_state) && session->method->session_want_refresh(ctx, session->method_state)) { + pr_verbose(ctx, "refreshing session with %P", peer); + session->handshakes_cleaned = true; + session->refreshing = true; + fastd_peer_schedule_handshake(ctx, peer, 0); + } +} + +static fastd_protocol_config_t* protocol_init(fastd_context_t *ctx) { + fastd_protocol_config_t *protocol_config = malloc(sizeof(fastd_protocol_config_t)); + + if (!ctx->conf->secret) + exit_error(ctx, "no secret key configured"); + + if (!read_key(protocol_config->key.secret.p, ctx->conf->secret)) + exit_error(ctx, "invalid secret key"); + + ecc_25519_work_t work; + ecc_25519_scalarmult_base(&work, &protocol_config->key.secret); + ecc_25519_store_packed(&protocol_config->key.public, &work); + + return protocol_config; +} + +static inline void hexdump(char out[65], const unsigned char d[32]) { + int i; + for (i = 0; i < 32; i++) + snprintf(out+2*i, 3, "%02x", d[i]); +} + +static size_t key_count(fastd_context_t *ctx, const unsigned char key[32]) { + size_t ret = 0; + + fastd_peer_config_t *p; + for (p = ctx->conf->peers; p; p = p->next) { + if (!p->protocol_config) + continue; + + if (memcmp(p->protocol_config->public_key.p, key, 32) == 0) + ret++; + } + + return ret; +} + +static void protocol_peer_configure(fastd_context_t *ctx, fastd_peer_config_t *peer_conf) { + if (peer_conf->protocol_config) + return; + + if (!peer_conf->key) { + pr_warn(ctx, "no key configured for `%s', disabling peer", peer_conf->name); + return; + } + + aligned_int256_t key; + if (!read_key(key.p, peer_conf->key)) { + pr_warn(ctx, "invalid key configured for `%s', disabling peer", peer_conf->name); + return; + } + + peer_conf->protocol_config = malloc(sizeof(fastd_protocol_peer_config_t)); + peer_conf->protocol_config->public_key = key; + + if (memcmp(peer_conf->protocol_config->public_key.p, ctx->conf->protocol_config->key.public.p, 32) == 0) + pr_debug(ctx, "found own key as `%s', ignoring peer", peer_conf->name); +} + +static bool protocol_peer_check(fastd_context_t *ctx, fastd_peer_config_t *peer_conf) { + if (!peer_conf->protocol_config) + return false; + + if (memcmp(peer_conf->protocol_config->public_key.p, ctx->conf->protocol_config->key.public.p, 32) == 0) + return false; + + if (key_count(ctx, peer_conf->protocol_config->public_key.p) > 1) { + char buf[65]; + hexdump(buf, peer_conf->protocol_config->public_key.p); + pr_warn(ctx, "more than one peer is configured with key %s, disabling %s", buf, peer_conf->name); + return false; + } + + return true; +} + +static bool protocol_peer_check_temporary(fastd_context_t *ctx, fastd_peer_t *peer) { + if (key_count(ctx, peer->protocol_config->public_key.p)) { + char buf[65]; + hexdump(buf, peer->protocol_config->public_key.p); + pr_info(ctx, "key %s is configured now, deleting temporary peer.", buf); + return false; + } + + return true; +} + +static void init_protocol_state(fastd_context_t *ctx) { + if (!ctx->protocol_state) { + ctx->protocol_state = calloc(1, sizeof(fastd_protocol_state_t)); + + ctx->protocol_state->prev_handshake_key.preferred_till = ctx->conf->long_ago; + ctx->protocol_state->handshake_key.preferred_till = ctx->conf->long_ago; + } +} + +static void new_handshake_key(fastd_context_t *ctx, keypair_t *key) { + fastd_random_bytes(ctx, key->secret.p, 32, false); + ecc_25519_gf_sanitize_secret(&key->secret, &key->secret); + + ecc_25519_work_t work; + ecc_25519_scalarmult_base(&work, &key->secret); + ecc_25519_store_packed(&key->public, &work); +} + +static void maintenance(fastd_context_t *ctx) { + init_protocol_state(ctx); + + if (!is_handshake_key_preferred(ctx, &ctx->protocol_state->handshake_key)) { + pr_debug(ctx, "generating new handshake key"); + + ctx->protocol_state->prev_handshake_key = ctx->protocol_state->handshake_key; + + ctx->protocol_state->handshake_key.serial++; + + new_handshake_key(ctx, &ctx->protocol_state->handshake_key.key1); + new_handshake_key(ctx, &ctx->protocol_state->handshake_key.key2); + + ctx->protocol_state->handshake_key.preferred_till = ctx->now; + ctx->protocol_state->handshake_key.preferred_till.tv_sec += 15; + + ctx->protocol_state->handshake_key.valid_till = ctx->now; + ctx->protocol_state->handshake_key.valid_till.tv_sec += 30; + } +} + +static void protocol_handshake_init(fastd_context_t *ctx, const fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer) { + maintenance(ctx); + + fastd_buffer_t buffer = fastd_handshake_new_init(ctx, 3*(4+PUBLICKEYBYTES) /* sender key, receipient key, handshake key */); + + fastd_handshake_add(ctx, &buffer, RECORD_SENDER_KEY, PUBLICKEYBYTES, ctx->conf->protocol_config->key.public.p); + + if (peer) + fastd_handshake_add(ctx, &buffer, RECORD_RECEIPIENT_KEY, PUBLICKEYBYTES, peer->protocol_config->public_key.p); + else + pr_debug(ctx, "sending handshake to unknown peer %I", remote_addr); + + fastd_handshake_add(ctx, &buffer, RECORD_SENDER_HANDSHAKE_KEY, PUBLICKEYBYTES, ctx->protocol_state->handshake_key.key1.public.p); + + fastd_send_handshake(ctx, sock, local_addr, remote_addr, peer, buffer); +} + + +static bool update_shared_handshake_key(fastd_context_t *ctx, const fastd_peer_t *peer, const handshake_key_t *handshake_key, const aligned_int256_t *peer_handshake_key) { + if (peer->protocol_state->last_handshake_serial == handshake_key->serial) { + if (memcmp(&peer->protocol_state->peer_handshake_key, peer_handshake_key, PUBLICKEYBYTES) == 0) + return true; + } + + fastd_sha256_t hashbuf; + fastd_sha256_blocks(&hashbuf, + handshake_key->key2.public.p, + peer_handshake_key->p, + ctx->conf->protocol_config->key.public.p, + peer->protocol_config->public_key.p, + NULL); + + ecc_int256_t d = {{0}}, e = {{0}}, eb, s; + + memcpy(d.p, hashbuf.b, HASHBYTES/2); + memcpy(e.p, hashbuf.b+HASHBYTES/2, HASHBYTES/2); + + d.p[15] |= 0x80; + e.p[15] |= 0x80; + + ecc_25519_gf_mult(&eb, &e, &ctx->conf->protocol_config->key.secret); + ecc_25519_gf_add(&s, &eb, &handshake_key->key2.secret); + + ecc_25519_work_t work, workX; + if (!ecc_25519_load_packed(&workX, peer_handshake_key)) + return false; + + ecc_25519_scalarmult(&work, &ecc_25519_gf_order, &workX); + if (!ecc_25519_is_identity(&work)) + return false; + + if (!ecc_25519_load_packed(&work, &peer->protocol_config->public_key)) + return false; + + ecc_25519_scalarmult(&work, &d, &work); + ecc_25519_add(&work, &workX, &work); + ecc_25519_scalarmult(&work, &s, &work); + + if (ecc_25519_is_identity(&work)) + return false; + + ecc_25519_store_packed(&peer->protocol_state->sigma, &work); + + fastd_sha256_blocks(&peer->protocol_state->shared_handshake_key, + handshake_key->key2.public.p, + peer_handshake_key->p, + ctx->conf->protocol_config->key.public.p, + peer->protocol_config->public_key.p, + peer->protocol_state->sigma.p, + NULL); + + peer->protocol_state->last_handshake_serial = handshake_key->serial; + peer->protocol_state->peer_handshake_key = *peer_handshake_key; + + return true; +} + +static void clear_shared_handshake_key(fastd_context_t *ctx UNUSED, const fastd_peer_t *peer) { + memset(&peer->protocol_state->sigma, 0, sizeof(peer->protocol_state->sigma)); + memset(&peer->protocol_state->shared_handshake_key, 0, sizeof(peer->protocol_state->shared_handshake_key)); + + peer->protocol_state->last_handshake_serial = 0; + memset(&peer->protocol_state->peer_handshake_key, 0, sizeof(peer->protocol_state->peer_handshake_key)); +} + +static void respond_handshake(fastd_context_t *ctx, const fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, + const handshake_key_t *handshake_key, const aligned_int256_t *peer_handshake_key, const fastd_handshake_t *handshake, const fastd_method_t *method) { + pr_debug(ctx, "responding handshake with %P[%I]...", peer, remote_addr); + + if (!update_shared_handshake_key(ctx, peer, handshake_key, peer_handshake_key)) + return; + + fastd_buffer_t buffer = fastd_handshake_new_reply(ctx, handshake, method, true, 4*(4+PUBLICKEYBYTES) + 2*(4+HASHBYTES)); + + fastd_handshake_add(ctx, &buffer, RECORD_SENDER_KEY, PUBLICKEYBYTES, ctx->conf->protocol_config->key.public.p); + fastd_handshake_add(ctx, &buffer, RECORD_RECEIPIENT_KEY, PUBLICKEYBYTES, peer->protocol_config->public_key.p); + fastd_handshake_add(ctx, &buffer, RECORD_SENDER_HANDSHAKE_KEY, PUBLICKEYBYTES, handshake_key->key2.public.p); + fastd_handshake_add(ctx, &buffer, RECORD_RECEIPIENT_HANDSHAKE_KEY, PUBLICKEYBYTES, peer_handshake_key->p); + + fastd_sha256_t hmacbuf; + + if (!ctx->conf->secure_handshakes) { + fastd_hmacsha256_blocks(&hmacbuf, peer->protocol_state->shared_handshake_key.w, ctx->conf->protocol_config->key.public.p, handshake_key->key2.public.p, NULL); + fastd_handshake_add(ctx, &buffer, RECORD_T, HASHBYTES, hmacbuf.b); + } + + memset(&hmacbuf, 0, sizeof(hmacbuf)); + fastd_handshake_add(ctx, &buffer, RECORD_TLV_MAC, HASHBYTES, hmacbuf.b); + fastd_hmacsha256(&hmacbuf, peer->protocol_state->shared_handshake_key.w, fastd_handshake_tlv_data(&buffer), fastd_handshake_tlv_len(&buffer)); + memcpy(buffer.data+buffer.len-HASHBYTES, hmacbuf.b, HASHBYTES); + + fastd_send_handshake(ctx, sock, local_addr, remote_addr, peer, buffer); +} + +static bool establish(fastd_context_t *ctx, fastd_peer_t *peer, const fastd_method_t *method, fastd_socket_t *sock, + const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, bool initiator, + const aligned_int256_t *A, const aligned_int256_t *B, const aligned_int256_t *X, + const aligned_int256_t *Y, const aligned_int256_t *sigma, uint64_t serial) { + if (serial <= peer->protocol_state->last_serial) { + pr_debug(ctx, "ignoring handshake from %P[%I] because of handshake key reuse", peer, remote_addr); + return false; + } + + pr_verbose(ctx, "%I authorized as %P", remote_addr, peer); + + if (!fastd_peer_claim_address(ctx, peer, sock, local_addr, remote_addr)) { + pr_warn(ctx, "can't set address %I which is used by a fixed peer", remote_addr); + fastd_peer_reset(ctx, peer); + return false; + } + + if (is_session_valid(ctx, &peer->protocol_state->session) && !is_session_valid(ctx, &peer->protocol_state->old_session)) { + if (peer->protocol_state->old_session.method) + peer->protocol_state->old_session.method->session_free(ctx, peer->protocol_state->old_session.method_state); + peer->protocol_state->old_session = peer->protocol_state->session; + } + else { + if (peer->protocol_state->session.method) + peer->protocol_state->session.method->session_free(ctx, peer->protocol_state->session.method_state); + } + + if (peer->protocol_state->old_session.method) { + if (peer->protocol_state->old_session.method != method) { + pr_debug(ctx, "method of %P[%I] has changed, terminating old session", peer, remote_addr); + peer->protocol_state->old_session.method->session_free(ctx, peer->protocol_state->old_session.method_state); + peer->protocol_state->old_session = (protocol_session_t){}; + } + else { + peer->protocol_state->old_session.method->session_superseded(ctx, peer->protocol_state->old_session.method_state); + } + } + + fastd_sha256_t hash; + fastd_sha256_blocks(&hash, X->p, Y->p, A->p, B->p, sigma->p, NULL); + + peer->protocol_state->session.established = ctx->now; + peer->protocol_state->session.handshakes_cleaned = false; + peer->protocol_state->session.refreshing = false; + peer->protocol_state->session.method = method; + peer->protocol_state->session.method_state = method->session_init(ctx, hash.b, HASHBYTES, initiator); + peer->protocol_state->last_serial = serial; + + fastd_peer_seen(ctx, peer); + + fastd_peer_set_established(ctx, peer); + + pr_verbose(ctx, "new session with %P established using method `%s'.", peer, method->name); + + if (initiator) + fastd_peer_schedule_handshake_default(ctx, peer); + else + send_empty(ctx, peer, &peer->protocol_state->session); + + return true; +} + +static inline bool has_field(const fastd_handshake_t *handshake, uint8_t type, size_t length) { + return (handshake->records[type].length == length); +} + +static void finish_handshake(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, const handshake_key_t *handshake_key, const aligned_int256_t *peer_handshake_key, + const fastd_handshake_t *handshake, const fastd_method_t *method) { + pr_debug(ctx, "finishing handshake with %P[%I]...", peer, remote_addr); + + fastd_sha256_t hashbuf; + fastd_sha256_blocks(&hashbuf, + peer_handshake_key->p, + handshake_key->key1.public.p, + peer->protocol_config->public_key.p, + ctx->conf->protocol_config->key.public.p, + NULL); + + ecc_int256_t d = {{0}}, e = {{0}}, da, s; + + memcpy(d.p, hashbuf.b, HASHBYTES/2); + memcpy(e.p, hashbuf.b+HASHBYTES/2, HASHBYTES/2); + + d.p[15] |= 0x80; + e.p[15] |= 0x80; + + ecc_25519_gf_mult(&da, &d, &ctx->conf->protocol_config->key.secret); + ecc_25519_gf_add(&s, &da, &handshake_key->key1.secret); + + ecc_25519_work_t work, workY; + if (!ecc_25519_load_packed(&workY, peer_handshake_key)) + return; + + ecc_25519_scalarmult(&work, &ecc_25519_gf_order, &workY); + if (!ecc_25519_is_identity(&work)) + return; + + if (!ecc_25519_load_packed(&work, &peer->protocol_config->public_key)) + return; + + ecc_25519_scalarmult(&work, &e, &work); + ecc_25519_add(&work, &workY, &work); + ecc_25519_scalarmult(&work, &s, &work); + + if (ecc_25519_is_identity(&work)) + return; + + aligned_int256_t sigma; + ecc_25519_store_packed(&sigma, &work); + + fastd_sha256_t shared_handshake_key; + fastd_sha256_blocks(&shared_handshake_key, + peer_handshake_key->p, + handshake_key->key1.public.p, + peer->protocol_config->public_key.p, + ctx->conf->protocol_config->key.public.p, + sigma.p, + NULL); + + bool valid; + if (has_field(handshake, RECORD_TLV_MAC, HASHBYTES)) { + uint8_t mac[HASHBYTES]; + memcpy(mac, handshake->records[RECORD_TLV_MAC].data, HASHBYTES); + memset(handshake->records[RECORD_TLV_MAC].data, 0, HASHBYTES); + + valid = fastd_hmacsha256_verify(mac, shared_handshake_key.w, handshake->tlv_data, handshake->tlv_len); + } + else { + valid = fastd_hmacsha256_blocks_verify(handshake->records[RECORD_T].data, shared_handshake_key.w, peer->protocol_config->public_key.p, peer_handshake_key->p, NULL); + } + + if (!valid) { + pr_warn(ctx, "received invalid protocol handshake response from %P[%I]", peer, remote_addr); + return; + } + + if (!establish(ctx, peer, method, sock, local_addr, remote_addr, true, &handshake_key->key1.public, peer_handshake_key, &ctx->conf->protocol_config->key.public, + &peer->protocol_config->public_key, &sigma, handshake_key->serial)) + return; + + fastd_buffer_t buffer = fastd_handshake_new_reply(ctx, handshake, method, false, 4*(4+PUBLICKEYBYTES) + 2*(4+HASHBYTES)); + + fastd_handshake_add(ctx, &buffer, RECORD_SENDER_KEY, PUBLICKEYBYTES, ctx->conf->protocol_config->key.public.p); + fastd_handshake_add(ctx, &buffer, RECORD_RECEIPIENT_KEY, PUBLICKEYBYTES, peer->protocol_config->public_key.p); + fastd_handshake_add(ctx, &buffer, RECORD_SENDER_HANDSHAKE_KEY, PUBLICKEYBYTES, handshake_key->key1.public.p); + fastd_handshake_add(ctx, &buffer, RECORD_RECEIPIENT_HANDSHAKE_KEY, PUBLICKEYBYTES, peer_handshake_key->p); + + fastd_sha256_t hmacbuf; + + if (!ctx->conf->secure_handshakes) { + fastd_hmacsha256_blocks(&hmacbuf, shared_handshake_key.w, ctx->conf->protocol_config->key.public.p, handshake_key->key1.public.p, NULL); + fastd_handshake_add(ctx, &buffer, RECORD_T, HASHBYTES, hmacbuf.b); + } + + memset(&hmacbuf, 0, sizeof(hmacbuf)); + fastd_handshake_add(ctx, &buffer, RECORD_TLV_MAC, HASHBYTES, hmacbuf.b); + fastd_hmacsha256(&hmacbuf, shared_handshake_key.w, fastd_handshake_tlv_data(&buffer), fastd_handshake_tlv_len(&buffer)); + memcpy(buffer.data+buffer.len-HASHBYTES, hmacbuf.b, HASHBYTES); + + fastd_send_handshake(ctx, sock, local_addr, remote_addr, peer, buffer); +} + +static void handle_finish_handshake(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, + fastd_peer_t *peer, const handshake_key_t *handshake_key, const aligned_int256_t *peer_handshake_key, + const fastd_handshake_t *handshake, const fastd_method_t *method) { + pr_debug(ctx, "handling handshake finish with %P[%I]...", peer, remote_addr); + + if (!update_shared_handshake_key(ctx, peer, handshake_key, peer_handshake_key)) + return; + + bool valid; + if (has_field(handshake, RECORD_TLV_MAC, HASHBYTES)) { + uint8_t mac[HASHBYTES]; + memcpy(mac, handshake->records[RECORD_TLV_MAC].data, HASHBYTES); + memset(handshake->records[RECORD_TLV_MAC].data, 0, HASHBYTES); + + valid = fastd_hmacsha256_verify(mac, peer->protocol_state->shared_handshake_key.w, handshake->tlv_data, handshake->tlv_len); + } + else { + valid = fastd_hmacsha256_blocks_verify(handshake->records[RECORD_T].data, peer->protocol_state->shared_handshake_key.w, peer->protocol_config->public_key.p, peer_handshake_key->p, NULL); + } + + if (!valid) { + pr_warn(ctx, "received invalid protocol handshake finish from %P[%I]", peer, remote_addr); + return; + } + + establish(ctx, peer, method, sock, local_addr, remote_addr, false, peer_handshake_key, &handshake_key->key2.public, &peer->protocol_config->public_key, + &ctx->conf->protocol_config->key.public, &peer->protocol_state->sigma, handshake_key->serial); + + clear_shared_handshake_key(ctx, peer); +} + +static fastd_peer_t* find_sender_key(fastd_context_t *ctx, const fastd_peer_address_t *address, const unsigned char key[32], fastd_peer_t *peers) { + errno = 0; + + fastd_peer_t *ret = NULL, *peer; + + for (peer = peers; peer; peer = peer->next) { + if (memcmp(peer->protocol_config->public_key.p, key, PUBLICKEYBYTES) == 0) { + if (!fastd_peer_matches_address(ctx, peer, address)) { + errno = EPERM; + return NULL; + } + + ret = peer; + continue; + } + + if (fastd_peer_owns_address(ctx, peer, address)) { + errno = EPERM; + return NULL; + } + } + + if (!ret) + errno = ENOENT; + + return ret; +} + +static fastd_peer_t* match_sender_key(fastd_context_t *ctx, const fastd_socket_t *sock, const fastd_peer_address_t *address, fastd_peer_t *peer, const unsigned char key[32]) { + errno = 0; + + if (sock->peer && peer != sock->peer) + exit_bug(ctx, "packet without correct peer set on dynamic socket"); + + if (peer) { + if (memcmp(peer->protocol_config->public_key.p, key, PUBLICKEYBYTES) == 0) + return peer; + + if (fastd_peer_owns_address(ctx, peer, address)) { + errno = EPERM; + return NULL; + } + } + + peer = find_sender_key(ctx, address, key, ctx->peers); + + if (!peer && errno == ENOENT) + peer = find_sender_key(ctx, address, key, ctx->peers_temp); + + return peer; +} + +static inline fastd_peer_t* add_temporary(fastd_context_t *ctx, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, const unsigned char key[32]) { + if (!fastd_peer_allow_unknown(ctx)) { + pr_debug(ctx, "ignoring handshake from %I (unknown key)", remote_addr); + return NULL; + } + + if (key_count(ctx, key)) { + pr_debug(ctx, "ignoring handshake from %I (disabled key)", remote_addr); + return NULL; + } + + fastd_peer_t *peer = fastd_peer_add_temporary(ctx); + + peer->protocol_config = malloc(sizeof(fastd_protocol_peer_config_t)); + memcpy(peer->protocol_config->public_key.p, key, PUBLICKEYBYTES); + + /* Ugly hack */ + peer->protocol_state->last_serial--; + + if (!fastd_peer_verify_temporary(ctx, peer, local_addr, remote_addr)) { + pr_debug(ctx, "ignoring handshake from %P[%I] (verification failed)", peer, remote_addr); + fastd_peer_delete(ctx, peer); + return NULL; + } + + return peer; +} + +static inline keypair_t* get_handshake_keypair(handshake_key_t *handshake_key, uint8_t type) { + return (type % 2) ? &handshake_key->key2 : &handshake_key->key1; +} + +static void protocol_handshake_handle(fastd_context_t *ctx, fastd_socket_t *sock, const fastd_peer_address_t *local_addr, const fastd_peer_address_t *remote_addr, fastd_peer_t *peer, const fastd_handshake_t *handshake, const fastd_method_t *method) { + bool temporary_added = false; + + maintenance(ctx); + + if (!has_field(handshake, RECORD_SENDER_KEY, PUBLICKEYBYTES)) { + pr_debug(ctx, "received handshake without sender key from %I", remote_addr); + return; + } + + peer = match_sender_key(ctx, sock, remote_addr, peer, handshake->records[RECORD_SENDER_KEY].data); + if (!peer) { + switch (errno) { + case EPERM: + pr_debug(ctx, "ignoring handshake from %I (incorrect source address)", remote_addr); + return; + + case ENOENT: + peer = add_temporary(ctx, local_addr, remote_addr, handshake->records[RECORD_SENDER_KEY].data); + if (peer) { + temporary_added = true; + break; + } + + return; + + default: + exit_bug(ctx, "match_sender_key: unknown error"); + } + } + + if (fastd_peer_is_temporary(peer) && !temporary_added) { + if (!fastd_peer_verify_temporary(ctx, peer, local_addr, remote_addr)) { + pr_debug(ctx, "ignoring handshake from %P[%I] (verification failed)", peer, remote_addr); + return; + } + } + + if (!fastd_peer_may_connect(ctx, peer)) { + pr_debug(ctx, "ignoring handshake from %P[%I] because of local constraints", peer, remote_addr); + return; + } + + if (backoff(ctx, peer)) { + pr_debug(ctx, "received repeated handshakes from %P[%I], ignoring", peer, remote_addr); + return; + } + + if (has_field(handshake, RECORD_RECEIPIENT_KEY, PUBLICKEYBYTES)) { + if (memcmp(ctx->conf->protocol_config->key.public.p, handshake->records[RECORD_RECEIPIENT_KEY].data, PUBLICKEYBYTES) != 0) { + pr_debug(ctx, "received protocol handshake with wrong receipient key from %P[%I]", peer, remote_addr); + return; + } + } + + if (!has_field(handshake, RECORD_SENDER_HANDSHAKE_KEY, PUBLICKEYBYTES)) { + pr_debug(ctx, "received handshake without sender handshake key from %P[%I]", peer, remote_addr); + return; + } + + aligned_int256_t peer_handshake_key; + memcpy(peer_handshake_key.p, handshake->records[RECORD_SENDER_HANDSHAKE_KEY].data, PUBLICKEYBYTES); + + if (handshake->type == 1) { + if (timespec_diff(&ctx->now, &peer->last_handshake_response) < (int)ctx->conf->min_handshake_interval*1000 + && fastd_peer_address_equal(remote_addr, &peer->last_handshake_response_address)) { + pr_debug(ctx, "not responding repeated handshake from %P[%I]", peer, remote_addr); + return; + } + + pr_verbose(ctx, "received handshake from %P[%I]%s%s", peer, remote_addr, handshake->peer_version ? " using fastd " : "", handshake->peer_version ?: ""); + + peer->last_handshake_response = ctx->now; + peer->last_handshake_response_address = *remote_addr; + respond_handshake(ctx, sock, local_addr, remote_addr, peer, &ctx->protocol_state->handshake_key, &peer_handshake_key, handshake, method); + return; + } + + if (!has_field(handshake, RECORD_RECEIPIENT_KEY, PUBLICKEYBYTES)) { + pr_debug(ctx, "received handshake reply without receipient key from %P[%I]", peer, remote_addr); + return; + } + + if (!has_field(handshake, RECORD_RECEIPIENT_HANDSHAKE_KEY, PUBLICKEYBYTES)) { + pr_debug(ctx, "received handshake reply without receipient handshake key from %P[%I]", peer, remote_addr); + return; + } + + if (!has_field(handshake, RECORD_TLV_MAC, HASHBYTES)) { + if (ctx->conf->secure_handshakes || !has_field(handshake, RECORD_T, HASHBYTES)) { + pr_debug(ctx, "received handshake reply without HMAC from %P[%I]", peer, remote_addr); + return; + } + } + + handshake_key_t *handshake_key; + if (is_handshake_key_valid(ctx, &ctx->protocol_state->handshake_key) && + memcmp(get_handshake_keypair(&ctx->protocol_state->handshake_key, handshake->type)->public.p, handshake->records[RECORD_RECEIPIENT_HANDSHAKE_KEY].data, PUBLICKEYBYTES) == 0) { + handshake_key = &ctx->protocol_state->handshake_key; + } + else if (is_handshake_key_valid(ctx, &ctx->protocol_state->prev_handshake_key) && + memcmp(get_handshake_keypair(&ctx->protocol_state->prev_handshake_key, handshake->type)->public.p, handshake->records[RECORD_RECEIPIENT_HANDSHAKE_KEY].data, PUBLICKEYBYTES) == 0) { + handshake_key = &ctx->protocol_state->prev_handshake_key; + } + else { + pr_debug(ctx, "received handshake reply with unexpected receipient handshake key from %P[%I]", peer, remote_addr); + return; + } + + switch (handshake->type) { + case 2: + pr_verbose(ctx, "received handshake response from %P[%I]%s%s", peer, remote_addr, handshake->peer_version ? " using fastd " : "", handshake->peer_version ?: ""); + + finish_handshake(ctx, sock, local_addr, remote_addr, peer, handshake_key, &peer_handshake_key, handshake, method); + break; + + case 3: + pr_debug(ctx, "received handshake finish from %P[%I]%s%s", peer, remote_addr, handshake->peer_version ? " using fastd " : "", handshake->peer_version ?: ""); + + handle_finish_handshake(ctx, sock, local_addr, remote_addr, peer, handshake_key, &peer_handshake_key, handshake, method); + break; + + default: + pr_debug(ctx, "received handshake reply with unknown type %u from %P[%I]", handshake->type, peer, remote_addr); + } +} + +static inline bool check_session(fastd_context_t *ctx, fastd_peer_t *peer) { + if (is_session_valid(ctx, &peer->protocol_state->session)) + return true; + + pr_verbose(ctx, "active session with %P timed out", peer); + fastd_peer_reset(ctx, peer); + return false; +} + +static void protocol_handle_recv(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer_t buffer) { + if (!peer->protocol_state || !check_session(ctx, peer)) + goto fail; + + fastd_buffer_t recv_buffer; + bool ok = false; + + if (is_session_valid(ctx, &peer->protocol_state->old_session)) { + if (peer->protocol_state->old_session.method->decrypt(ctx, peer, peer->protocol_state->old_session.method_state, &recv_buffer, buffer)) + ok = true; + } + + if (!ok) { + if (peer->protocol_state->session.method->decrypt(ctx, peer, peer->protocol_state->session.method_state, &recv_buffer, buffer)) { + ok = true; + + if (peer->protocol_state->old_session.method) { + pr_debug(ctx, "invalidating old session with %P", peer); + peer->protocol_state->old_session.method->session_free(ctx, peer->protocol_state->old_session.method_state); + peer->protocol_state->old_session = (protocol_session_t){}; + } + + if (!peer->protocol_state->session.handshakes_cleaned) { + pr_debug(ctx, "cleaning left handshakes with %P", peer); + fastd_peer_unschedule_handshake(ctx, peer); + peer->protocol_state->session.handshakes_cleaned = true; + + if (peer->protocol_state->session.method->session_is_initiator(ctx, peer->protocol_state->session.method_state)) + send_empty(ctx, peer, &peer->protocol_state->session); + } + + check_session_refresh(ctx, peer); + } + } + + if (!ok) { + pr_verbose(ctx, "verification failed for packet received from %P", peer); + goto fail; + } + + fastd_peer_seen(ctx, peer); + + if (recv_buffer.len) + fastd_handle_receive(ctx, peer, recv_buffer); + else + fastd_buffer_free(recv_buffer); + + return; + + fail: + fastd_buffer_free(buffer); +} + +static void session_send(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer_t buffer, protocol_session_t *session) { + size_t stat_size = buffer.len; + + fastd_buffer_t send_buffer; + if (!session->method->encrypt(ctx, peer, session->method_state, &send_buffer, buffer)) { + fastd_buffer_free(buffer); + return; + } + + fastd_send(ctx, peer->sock, &peer->local_address, &peer->address, peer, send_buffer, stat_size); + peer->last_send = ctx->now; +} + +static void protocol_send(fastd_context_t *ctx, fastd_peer_t *peer, fastd_buffer_t buffer) { + if (!peer->protocol_state || !fastd_peer_is_established(peer) || !check_session(ctx, peer)) { + fastd_buffer_free(buffer); + return; + } + + check_session_refresh(ctx, peer); + + if (peer->protocol_state->session.method->session_is_initiator(ctx, peer->protocol_state->session.method_state) && is_session_valid(ctx, &peer->protocol_state->old_session)) { + pr_debug2(ctx, "sending packet for old session to %P", peer); + session_send(ctx, peer, buffer, &peer->protocol_state->old_session); + } + else { + session_send(ctx, peer, buffer, &peer->protocol_state->session); + } +} + +static void send_empty(fastd_context_t *ctx, fastd_peer_t *peer, protocol_session_t *session) { + session_send(ctx, peer, fastd_buffer_alloc(ctx, 0, alignto(session->method->min_encrypt_head_space(ctx), 8), session->method->min_encrypt_tail_space(ctx)), session); +} + +static void protocol_init_peer_state(fastd_context_t *ctx, fastd_peer_t *peer) { + init_protocol_state(ctx); + + if (peer->protocol_state) + exit_bug(ctx, "tried to reinit peer state"); + + peer->protocol_state = calloc(1, sizeof(fastd_protocol_peer_state_t)); + peer->protocol_state->last_serial = ctx->protocol_state->handshake_key.serial; +} + +static void reset_session(fastd_context_t *ctx, protocol_session_t *session) { + if (session->method) + session->method->session_free(ctx, session->method_state); + secure_memzero(session, sizeof(protocol_session_t)); +} + +static void protocol_reset_peer_state(fastd_context_t *ctx, fastd_peer_t *peer) { + if (!peer->protocol_state) + return; + + reset_session(ctx, &peer->protocol_state->old_session); + reset_session(ctx, &peer->protocol_state->session); +} + +static void protocol_free_peer_state(fastd_context_t *ctx, fastd_peer_t *peer) { + if (peer->protocol_state) { + reset_session(ctx, &peer->protocol_state->old_session); + reset_session(ctx, &peer->protocol_state->session); + + free(peer->protocol_state); + } +} + +static inline void print_hexdump(const char *desc, unsigned char d[32]) { + char buf[65]; + hexdump(buf, d); + + printf("%s%s\n", desc, buf); +} + +static void protocol_generate_key(fastd_context_t *ctx) { + ecc_int256_t secret_key; + ecc_int256_t public_key; + + if (!ctx->conf->machine_readable) + pr_info(ctx, "Reading 32 bytes from /dev/random..."); + + fastd_random_bytes(ctx, secret_key.p, 32, true); + ecc_25519_gf_sanitize_secret(&secret_key, &secret_key); + + ecc_25519_work_t work; + ecc_25519_scalarmult_base(&work, &secret_key); + ecc_25519_store_packed(&public_key, &work); + + if (ctx->conf->machine_readable) { + print_hexdump("", secret_key.p); + } + else { + print_hexdump("Secret: ", secret_key.p); + print_hexdump("Public: ", public_key.p); + } +} + +static void protocol_show_key(fastd_context_t *ctx) { + if (ctx->conf->machine_readable) + print_hexdump("", ctx->conf->protocol_config->key.public.p); + else + print_hexdump("Public: ", ctx->conf->protocol_config->key.public.p); +} + +static void protocol_set_shell_env(fastd_context_t *ctx, const fastd_peer_t *peer) { + char buf[65]; + + hexdump(buf, ctx->conf->protocol_config->key.public.p); + setenv("LOCAL_KEY", buf, 1); + + if (peer && peer->protocol_config) { + hexdump(buf, peer->protocol_config->public_key.p); + setenv("PEER_KEY", buf, 1); + } + else { + unsetenv("PEER_KEY"); + } +} + +static bool protocol_describe_peer(const fastd_context_t *ctx UNUSED, const fastd_peer_t *peer, char *buf, size_t len) { + if (peer && peer->protocol_config) { + char dumpbuf[65]; + + hexdump(dumpbuf, peer->protocol_config->public_key.p); + snprintf(buf, len, "%.16s", dumpbuf); + return true; + } + else { + return false; + } +} + +const fastd_protocol_t fastd_protocol_ec25519_fhmqvc = { + .name = "ec25519-fhmqvc", + + .init = protocol_init, + .peer_configure = protocol_peer_configure, + .peer_check = protocol_peer_check, + .peer_check_temporary = protocol_peer_check_temporary, + + .handshake_init = protocol_handshake_init, + .handshake_handle = protocol_handshake_handle, + + .handle_recv = protocol_handle_recv, + .send = protocol_send, + + .init_peer_state = protocol_init_peer_state, + .reset_peer_state = protocol_reset_peer_state, + .free_peer_state = protocol_free_peer_state, + + .generate_key = protocol_generate_key, + .show_key = protocol_show_key, + .set_shell_env = protocol_set_shell_env, + .describe_peer = protocol_describe_peer, +}; |