/*
sptps.c -- Simple Peer-to-Peer Security
- Copyright (C) 2011-2014 Guus Sliepen <guus@tinc-vpn.org>,
+ Copyright (C) 2011-2015 Guus Sliepen <guus@tinc-vpn.org>,
2010 Brandon L. Black <blblack@gmail.com>
This program is free software; you can redistribute it and/or modify
}
// Send a record (private version, accepts all record types, handles encryption and authentication).
static bool send_record_priv(sptps_t *s, uint8_t type, const void *data, uint16_t len) {
- if(s->datagram)
+ if(s->datagram) {
return send_record_priv_datagram(s, type, data, len);
+ }
char buffer[len + 19UL];
bool sptps_send_record(sptps_t *s, uint8_t type, const void *data, uint16_t len) {
// Sanity checks: application cannot send data before handshake is finished,
// and only record types 0..127 are allowed.
- if(!s->outstate)
+ if(!s->outstate) {
return error(s, EINVAL, "Handshake phase not finished yet");
+ }
- if(type >= SPTPS_HANDSHAKE)
+ if(type >= SPTPS_HANDSHAKE) {
return error(s, EINVAL, "Invalid application record type");
+ }
return send_record_priv(s, type, data, len);
}
size_t keylen = ECDH_SIZE;
// Make room for our KEX message, which we will keep around since send_sig() needs it.
- if(s->mykex)
+ if(s->mykex) {
return false;
+ }
+
s->mykex = realloc(s->mykex, 1 + 32 + keylen);
- if(!s->mykex)
+
+ if(!s->mykex) {
return error(s, errno, strerror(errno));
+ }
// Set version byte to zero.
s->mykex[0] = SPTPS_VERSION;
randomize(s->mykex + 1, 32);
// Create a new ECDH public key.
- if(!(s->ecdh = ecdh_generate_public(s->mykex + 1 + 32)))
+ if(!(s->ecdh = ecdh_generate_public(s->mykex + 1 + 32))) {
return error(s, EINVAL, "Failed to generate ECDH public key");
+ }
return send_record_priv(s, SPTPS_HANDSHAKE, s->mykex, 1 + 32 + keylen);
}
memcpy(msg + 1 + 2 * (33 + keylen), s->label, s->labellen);
// Sign the result.
- if(!ecdsa_sign(s->mykey, msg, sizeof msg, sig))
+ if(!ecdsa_sign(s->mykey, msg, sizeof(msg), sig)) {
return error(s, EINVAL, "Failed to sign SIG record");
+ }
// Send the SIG exchange record.
- return send_record_priv(s, SPTPS_HANDSHAKE, sig, sizeof sig);
+ return send_record_priv(s, SPTPS_HANDSHAKE, sig, sizeof(sig));
}
// Generate key material from the shared secret created from the ECDHE key exchange.
if(!s->outstate) {
s->incipher = chacha_poly1305_init();
s->outcipher = chacha_poly1305_init();
- if(!s->incipher || !s->outcipher)
+
+ if(!s->incipher || !s->outcipher) {
return error(s, EINVAL, "Failed to open cipher");
+ }
}
// Allocate memory for key material
size_t keylen = 2 * CHACHA_POLY1305_KEYLEN;
s->key = realloc(s->key, keylen);
- if(!s->key)
+
+ if(!s->key) {
return error(s, errno, strerror(errno));
+ }
// Create the HMAC seed, which is "key expansion" + session label + server nonce + client nonce
char seed[s->labellen + 64 + 13];
- strcpy(seed, "key expansion");
+ memcpy(seed, "key expansion", 13);
+
if(s->initiator) {
memcpy(seed + 13, s->mykex + 1, 32);
memcpy(seed + 45, s->hiskex + 1, 32);
memcpy(seed + 13, s->hiskex + 1, 32);
memcpy(seed + 45, s->mykex + 1, 32);
}
+
memcpy(seed + 77, s->label, s->labellen);
// Use PRF to generate the key material
- if(!prf(shared, len, seed, s->labellen + 64 + 13, s->key, keylen))
+ if(!prf(shared, len, seed, s->labellen + 64 + 13, s->key, keylen)) {
return error(s, EINVAL, "Failed to generate key material");
+ }
return true;
}
// Receive an ACKnowledgement record.
static bool receive_ack(sptps_t *s, const char *data, uint16_t len) {
- if(len)
+ if(len) {
return error(s, EIO, "Invalid ACK record length");
+ }
if(s->initiator) {
- if(!chacha_poly1305_set_key(s->incipher, s->key))
+ if(!chacha_poly1305_set_key(s->incipher, s->key)) {
return error(s, EINVAL, "Failed to set counter");
+ }
} else {
- if(!chacha_poly1305_set_key(s->incipher, s->key + CHACHA_POLY1305_KEYLEN))
+ if(!chacha_poly1305_set_key(s->incipher, s->key + CHACHA_POLY1305_KEYLEN)) {
return error(s, EINVAL, "Failed to set counter");
+ }
}
free(s->key);
// Receive a Key EXchange record, respond by sending a SIG record.
static bool receive_kex(sptps_t *s, const char *data, uint16_t len) {
// Verify length of the HELLO record
- if(len != 1 + 32 + ECDH_SIZE)
+ if(len != 1 + 32 + ECDH_SIZE) {
return error(s, EIO, "Invalid KEX record length");
+ }
// Ignore version number for now.
// Make a copy of the KEX message, send_sig() and receive_sig() need it
- if(s->hiskex)
+ if(s->hiskex) {
return error(s, EINVAL, "Received a second KEX message before first has been processed");
+ }
+
s->hiskex = realloc(s->hiskex, len);
- if(!s->hiskex)
+
+ if(!s->hiskex) {
return error(s, errno, strerror(errno));
+ }
memcpy(s->hiskex, data, len);
- return send_sig(s);
+ if(s->initiator) {
+ return send_sig(s);
+ } else {
+ return true;
+ }
}
// Receive a SIGnature record, verify it, if it passed, compute the shared secret and calculate the session keys.
size_t siglen = ecdsa_size(s->hiskey);
// Verify length of KEX record.
- if(len != siglen)
+ if(len != siglen) {
return error(s, EIO, "Invalid KEX record length");
+ }
// Concatenate both KEX messages, plus tag indicating if it is from the connection originator
char msg[(1 + 32 + keylen) * 2 + 1 + s->labellen];
memcpy(msg + 1 + 2 * (33 + keylen), s->label, s->labellen);
// Verify signature.
- if(!ecdsa_verify(s->hiskey, msg, sizeof msg, data))
+ if(!ecdsa_verify(s->hiskey, msg, sizeof(msg), data)) {
return error(s, EIO, "Failed to verify SIG record");
+ }
// Compute shared secret.
char shared[ECDH_SHARED_SIZE];
- if(!ecdh_compute_shared(s->ecdh, s->hiskex + 1 + 32, shared))
+
+ if(!ecdh_compute_shared(s->ecdh, s->hiskex + 1 + 32, shared)) {
return error(s, EINVAL, "Failed to compute ECDH shared secret");
+ }
+
s->ecdh = NULL;
// Generate key material from shared secret.
- if(!generate_key_material(s, shared, sizeof shared))
+ if(!generate_key_material(s, shared, sizeof(shared))) {
+ return false;
+ }
+
+ if(!s->initiator && !send_sig(s)) {
return false;
+ }
free(s->mykex);
free(s->hiskex);
s->hiskex = NULL;
// Send cipher change record
- if(s->outstate && !send_ack(s))
+ if(s->outstate && !send_ack(s)) {
return false;
+ }
// TODO: only set new keys after ACK has been set/received
if(s->initiator) {
- if(!chacha_poly1305_set_key(s->outcipher, s->key + CHACHA_POLY1305_KEYLEN))
+ if(!chacha_poly1305_set_key(s->outcipher, s->key + CHACHA_POLY1305_KEYLEN)) {
return error(s, EINVAL, "Failed to set key");
+ }
} else {
- if(!chacha_poly1305_set_key(s->outcipher, s->key))
+ if(!chacha_poly1305_set_key(s->outcipher, s->key)) {
return error(s, EINVAL, "Failed to set key");
+ }
}
return true;
// Force another Key EXchange (for testing purposes).
bool sptps_force_kex(sptps_t *s) {
- if(!s->outstate || s->state != SPTPS_SECONDARY_KEX)
+ if(!s->outstate || s->state != SPTPS_SECONDARY_KEX) {
return error(s, EINVAL, "Cannot force KEX in current state");
+ }
s->state = SPTPS_KEX;
return send_kex(s);
static bool receive_handshake(sptps_t *s, const char *data, uint16_t len) {
// Only a few states to deal with handshaking.
switch(s->state) {
- case SPTPS_SECONDARY_KEX:
- // We receive a secondary KEX request, first respond by sending our own.
- if(!send_kex(s))
- return false;
- case SPTPS_KEX:
- // We have sent our KEX request, we expect our peer to sent one as well.
- if(!receive_kex(s, data, len))
- return false;
- s->state = SPTPS_SIG;
- return true;
- case SPTPS_SIG:
- // If we already sent our secondary public ECDH key, we expect the peer to send his.
- if(!receive_sig(s, data, len))
+ case SPTPS_SECONDARY_KEX:
+
+ // We receive a secondary KEX request, first respond by sending our own.
+ if(!send_kex(s)) {
+ return false;
+ }
+
+ case SPTPS_KEX:
+
+ // We have sent our KEX request, we expect our peer to sent one as well.
+ if(!receive_kex(s, data, len)) {
+ return false;
+ }
+
+ s->state = SPTPS_SIG;
+ return true;
+
+ case SPTPS_SIG:
+
+ // If we already sent our secondary public ECDH key, we expect the peer to send his.
+ if(!receive_sig(s, data, len)) {
+ return false;
+ }
+
+ if(s->outstate) {
+ s->state = SPTPS_ACK;
+ } else {
+ s->outstate = true;
+
+ if(!receive_ack(s, NULL, 0)) {
return false;
- if(s->outstate)
- s->state = SPTPS_ACK;
- else {
- s->outstate = true;
- if(!receive_ack(s, NULL, 0))
- return false;
- s->receive_record(s->handle, SPTPS_HANDSHAKE, NULL, 0);
- s->state = SPTPS_SECONDARY_KEX;
}
- return true;
- case SPTPS_ACK:
- // We expect a handshake message to indicate transition to the new keys.
- if(!receive_ack(s, data, len))
- return false;
s->receive_record(s->handle, SPTPS_HANDSHAKE, NULL, 0);
s->state = SPTPS_SECONDARY_KEX;
- return true;
- // TODO: split ACK into a VERify and ACK?
- default:
- return error(s, EIO, "Invalid session state %d", s->state);
+ }
+
+ return true;
+
+ case SPTPS_ACK:
+
+ // We expect a handshake message to indicate transition to the new keys.
+ if(!receive_ack(s, data, len)) {
+ return false;
+ }
+
+ s->receive_record(s->handle, SPTPS_HANDSHAKE, NULL, 0);
+ s->state = SPTPS_SECONDARY_KEX;
+ return true;
+
+ // TODO: split ACK into a VERify and ACK?
+ default:
+ return error(s, EIO, "Invalid session state %d", s->state);
}
}
if(seqno >= s->inseqno + s->replaywin * 8) {
// Prevent packets that jump far ahead of the queue from causing many others to be dropped.
bool farfuture = s->farfuture < s->replaywin >> 2;
- if (update_state)
+
+ if(update_state) {
s->farfuture++;
- if(farfuture)
- return error(s, EIO, "Packet is %d seqs in the future, dropped (%u)\n", seqno - s->inseqno, s->farfuture);
+ }
+
+ if(farfuture) {
+ return update_state ? error(s, EIO, "Packet is %d seqs in the future, dropped (%u)\n", seqno - s->inseqno, s->farfuture) : false;
+ }
// Unless we have seen lots of them, in which case we consider the others lost.
- warning(s, "Lost %d packets\n", seqno - s->inseqno);
- if (update_state) {
+ if(update_state) {
+ warning(s, "Lost %d packets\n", seqno - s->inseqno);
+ }
+
+ if(update_state) {
// Mark all packets in the replay window as being late.
memset(s->late, 255, s->replaywin);
}
- } else if (seqno < s->inseqno) {
+ } else if(seqno < s->inseqno) {
// If the sequence number is farther in the past than the bitmap goes, or if the packet was already received, drop it.
- if((s->inseqno >= s->replaywin * 8 && seqno < s->inseqno - s->replaywin * 8) || !(s->late[(seqno / 8) % s->replaywin] & (1 << seqno % 8)))
- return error(s, EIO, "Received late or replayed packet, seqno %d, last received %d\n", seqno, s->inseqno);
- } else if (update_state) {
+ if((s->inseqno >= s->replaywin * 8 && seqno < s->inseqno - s->replaywin * 8) || !(s->late[(seqno / 8) % s->replaywin] & (1 << seqno % 8))) {
+ return update_state ? error(s, EIO, "Received late or replayed packet, seqno %d, last received %d\n", seqno, s->inseqno) : false;
+ }
+ } else if(update_state) {
// We missed some packets. Mark them in the bitmap as being late.
- for(int i = s->inseqno; i < seqno; i++)
+ for(int i = s->inseqno; i < seqno; i++) {
s->late[(i / 8) % s->replaywin] |= 1 << i % 8;
+ }
}
}
- if (update_state) {
+ if(update_state) {
// Mark the current packet as not being late.
s->late[(seqno / 8) % s->replaywin] &= ~(1 << seqno % 8);
s->farfuture = 0;
}
}
- if (update_state) {
- if(seqno >= s->inseqno)
+ if(update_state) {
+ if(seqno >= s->inseqno) {
s->inseqno = seqno + 1;
+ }
- if(!s->inseqno)
+ if(!s->inseqno) {
s->received = 0;
- else
+ } else {
s->received++;
+ }
}
return true;
// Check datagram for valid HMAC
bool sptps_verify_datagram(sptps_t *s, const void *data, size_t len) {
- if(!s->instate || len < 21)
+ if(!s->instate || len < 21) {
return error(s, EIO, "Received short packet");
+ }
uint32_t seqno;
memcpy(&seqno, data, 4);
seqno = ntohl(seqno);
- if (!sptps_check_seqno(s, seqno, false))
+
+ if(!sptps_check_seqno(s, seqno, false)) {
return false;
+ }
char buffer[len];
size_t outlen;
// Receive incoming data, datagram version.
static bool sptps_receive_data_datagram(sptps_t *s, const char *data, size_t len) {
- if(len < (s->instate ? 21 : 5))
+ if(len < (s->instate ? 21 : 5)) {
return error(s, EIO, "Received short packet");
+ }
uint32_t seqno;
memcpy(&seqno, data, 4);
seqno = ntohl(seqno);
+ data += 4;
+ len -= 4;
if(!s->instate) {
- if(seqno != s->inseqno)
+ if(seqno != s->inseqno) {
return error(s, EIO, "Invalid packet seqno: %d != %d", seqno, s->inseqno);
+ }
s->inseqno = seqno + 1;
- uint8_t type = data[4];
+ uint8_t type = *(data++);
+ len--;
- if(type != SPTPS_HANDSHAKE)
+ if(type != SPTPS_HANDSHAKE) {
return error(s, EIO, "Application record received before handshake finished");
+ }
- return receive_handshake(s, data + 5, len - 5);
+ return receive_handshake(s, data, len);
}
// Decrypt
char buffer[len];
-
size_t outlen;
- if(!chacha_poly1305_decrypt(s->incipher, seqno, data + 4, len - 4, buffer, &outlen))
+ if(!chacha_poly1305_decrypt(s->incipher, seqno, data, len, buffer, &outlen)) {
return error(s, EIO, "Failed to decrypt and verify packet");
+ }
- if(!sptps_check_seqno(s, seqno, true))
+ if(!sptps_check_seqno(s, seqno, true)) {
return false;
+ }
// Append a NULL byte for safety.
- buffer[len - 20] = 0;
+ buffer[outlen] = 0;
- uint8_t type = buffer[0];
+ data = buffer;
+ len = outlen;
+
+ uint8_t type = *(data++);
+ len--;
if(type < SPTPS_HANDSHAKE) {
- if(!s->instate)
+ if(!s->instate) {
return error(s, EIO, "Application record received before handshake finished");
- if(!s->receive_record(s->handle, type, buffer + 1, len - 21))
+ }
+
+ if(!s->receive_record(s->handle, type, data, len)) {
return false;
+ }
} else if(type == SPTPS_HANDSHAKE) {
- if(!receive_handshake(s, buffer + 1, len - 21))
+ if(!receive_handshake(s, data, len)) {
return false;
+ }
} else {
return error(s, EIO, "Invalid record type %d", type);
}
}
// Receive incoming data. Check if it contains a complete record, if so, handle it.
-bool sptps_receive_data(sptps_t *s, const void *data, size_t len) {
- if(!s->state)
+size_t sptps_receive_data(sptps_t *s, const void *data, size_t len) {
+ size_t total_read = 0;
+
+ if(!s->state) {
return error(s, EIO, "Invalid session state zero");
+ }
- if(s->datagram)
- return sptps_receive_data_datagram(s, data, len);
+ if(s->datagram) {
+ return sptps_receive_data_datagram(s, data, len) ? len : false;
+ }
- while(len) {
- // First read the 2 length bytes.
- if(s->buflen < 2) {
- size_t toread = 2 - s->buflen;
- if(toread > len)
- toread = len;
+ // First read the 2 length bytes.
+ if(s->buflen < 2) {
+ size_t toread = 2 - s->buflen;
+
+ if(toread > len) {
+ toread = len;
+ }
- memcpy(s->inbuf + s->buflen, data, toread);
+ memcpy(s->inbuf + s->buflen, data, toread);
- s->buflen += toread;
- len -= toread;
- data += toread;
+ total_read += toread;
+ s->buflen += toread;
+ len -= toread;
+ data += toread;
- // Exit early if we don't have the full length.
- if(s->buflen < 2)
- return true;
+ // Exit early if we don't have the full length.
+ if(s->buflen < 2) {
+ return total_read;
+ }
- // Get the length bytes
+ // Get the length bytes
- memcpy(&s->reclen, s->inbuf, 2);
- s->reclen = ntohs(s->reclen);
+ memcpy(&s->reclen, s->inbuf, 2);
+ s->reclen = ntohs(s->reclen);
- // If we have the length bytes, ensure our buffer can hold the whole request.
- s->inbuf = realloc(s->inbuf, s->reclen + 19UL);
- if(!s->inbuf)
- return error(s, errno, strerror(errno));
+ // If we have the length bytes, ensure our buffer can hold the whole request.
+ s->inbuf = realloc(s->inbuf, s->reclen + 19UL);
- // Exit early if we have no more data to process.
- if(!len)
- return true;
+ if(!s->inbuf) {
+ return error(s, errno, strerror(errno));
}
- // Read up to the end of the record.
- size_t toread = s->reclen + (s->instate ? 19UL : 3UL) - s->buflen;
- if(toread > len)
- toread = len;
+ // Exit early if we have no more data to process.
+ if(!len) {
+ return total_read;
+ }
+ }
- memcpy(s->inbuf + s->buflen, data, toread);
- s->buflen += toread;
- len -= toread;
- data += toread;
+ // Read up to the end of the record.
+ size_t toread = s->reclen + (s->instate ? 19UL : 3UL) - s->buflen;
+
+ if(toread > len) {
+ toread = len;
+ }
+
+ memcpy(s->inbuf + s->buflen, data, toread);
+ total_read += toread;
+ s->buflen += toread;
- // If we don't have a whole record, exit.
- if(s->buflen < s->reclen + (s->instate ? 19UL : 3UL))
- return true;
+ // If we don't have a whole record, exit.
+ if(s->buflen < s->reclen + (s->instate ? 19UL : 3UL)) {
+ return total_read;
+ }
- // Update sequence number.
+ // Update sequence number.
- uint32_t seqno = s->inseqno++;
+ uint32_t seqno = s->inseqno++;
- // Check HMAC and decrypt.
- if(s->instate) {
- if(!chacha_poly1305_decrypt(s->incipher, seqno, s->inbuf + 2UL, s->reclen + 17UL, s->inbuf + 2UL, NULL))
- return error(s, EINVAL, "Failed to decrypt and verify record");
+ // Check HMAC and decrypt.
+ if(s->instate) {
+ if(!chacha_poly1305_decrypt(s->incipher, seqno, s->inbuf + 2UL, s->reclen + 17UL, s->inbuf + 2UL, NULL)) {
+ return error(s, EINVAL, "Failed to decrypt and verify record");
}
+ }
- // Append a NULL byte for safety.
- s->inbuf[s->reclen + 3UL] = 0;
+ // Append a NULL byte for safety.
+ s->inbuf[s->reclen + 3UL] = 0;
- uint8_t type = s->inbuf[2];
+ uint8_t type = s->inbuf[2];
- if(type < SPTPS_HANDSHAKE) {
- if(!s->instate)
- return error(s, EIO, "Application record received before handshake finished");
- if(!s->receive_record(s->handle, type, s->inbuf + 3, s->reclen))
- return false;
- } else if(type == SPTPS_HANDSHAKE) {
- if(!receive_handshake(s, s->inbuf + 3, s->reclen))
- return false;
- } else {
- return error(s, EIO, "Invalid record type %d", type);
+ if(type < SPTPS_HANDSHAKE) {
+ if(!s->instate) {
+ return error(s, EIO, "Application record received before handshake finished");
}
- s->buflen = 0;
+ if(!s->receive_record(s->handle, type, s->inbuf + 3, s->reclen)) {
+ return false;
+ }
+ } else if(type == SPTPS_HANDSHAKE) {
+ if(!receive_handshake(s, s->inbuf + 3, s->reclen)) {
+ return false;
+ }
+ } else {
+ return error(s, EIO, "Invalid record type %d", type);
}
- return true;
+ s->buflen = 0;
+
+ return total_read;
}
// Start a SPTPS session.
bool sptps_start(sptps_t *s, void *handle, bool initiator, bool datagram, ecdsa_t *mykey, ecdsa_t *hiskey, const void *label, size_t labellen, send_data_t send_data, receive_record_t receive_record) {
// Initialise struct sptps
- memset(s, 0, sizeof *s);
+ memset(s, 0, sizeof(*s));
s->handle = handle;
s->initiator = initiator;
s->mykey = mykey;
s->hiskey = hiskey;
s->replaywin = sptps_replaywin;
+
if(s->replaywin) {
s->late = malloc(s->replaywin);
- if(!s->late)
+
+ if(!s->late) {
return error(s, errno, strerror(errno));
+ }
+
memset(s->late, 0, s->replaywin);
}
s->label = malloc(labellen);
- if(!s->label)
+
+ if(!s->label) {
return error(s, errno, strerror(errno));
+ }
if(!datagram) {
s->inbuf = malloc(7);
- if(!s->inbuf)
+
+ if(!s->inbuf) {
return error(s, errno, strerror(errno));
+ }
+
s->buflen = 0;
}
free(s->key);
free(s->label);
free(s->late);
- memset(s, 0, sizeof *s);
+ memset(s, 0, sizeof(*s));
return true;
}
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