#include "chacha-poly1305/chacha-poly1305.h"
#include "ecdh.h"
#include "ecdsa.h"
-#include "logger.h"
#include "prf.h"
#include "sptps.h"
#include "random.h"
+#include "xalloc.h"
unsigned int sptps_replaywin = 16;
va_end(ap);
}
+static sptps_kex_t *new_sptps_kex(void) {
+ return xzalloc(sizeof(sptps_kex_t));
+}
+
+static void free_sptps_kex(sptps_kex_t *kex) {
+ xzfree(kex, sizeof(sptps_kex_t));
+}
+
+static sptps_key_t *new_sptps_key(void) {
+ return xzalloc(sizeof(sptps_key_t));
+}
+
+static void free_sptps_key(sptps_key_t *key) {
+ xzfree(key, sizeof(sptps_key_t));
+}
+
// Send a record (datagram version, accepts all record types, handles encryption and authentication).
static bool send_record_priv_datagram(sptps_t *s, uint8_t type, const void *data, uint16_t len) {
uint8_t *buffer = alloca(len + 21UL);
// Send a Key EXchange record, containing a random nonce and an ECDHE public key.
static bool send_kex(sptps_t *s) {
- size_t keylen = ECDH_SIZE;
-
// Make room for our KEX message, which we will keep around since send_sig() needs it.
if(s->mykex) {
return false;
}
- s->mykex = realloc(s->mykex, 1 + 32 + keylen);
-
- if(!s->mykex) {
- return error(s, errno, strerror(errno));
- }
+ s->mykex = new_sptps_kex();
// Set version byte to zero.
- s->mykex[0] = SPTPS_VERSION;
+ s->mykex->version = SPTPS_VERSION;
// Create a random nonce.
- randomize(s->mykex + 1, 32);
+ randomize(s->mykex->nonce, ECDH_SIZE);
// Create a new ECDH public key.
- if(!(s->ecdh = ecdh_generate_public(s->mykex + 1 + 32))) {
+ if(!(s->ecdh = ecdh_generate_public(s->mykex->pubkey))) {
return error(s, EINVAL, "Failed to generate ECDH public key");
}
- return send_record_priv(s, SPTPS_HANDSHAKE, s->mykex, 1 + 32 + keylen);
+ return send_record_priv(s, SPTPS_HANDSHAKE, s->mykex, sizeof(sptps_kex_t));
+}
+
+static size_t sigmsg_len(size_t labellen) {
+ return 1 + 2 * sizeof(sptps_kex_t) + labellen;
+}
+
+static void fill_msg(uint8_t *msg, bool initiator, const sptps_kex_t *kex0, const sptps_kex_t *kex1, const sptps_t *s) {
+ *msg = initiator, msg++;
+ memcpy(msg, kex0, sizeof(*kex0)), msg += sizeof(*kex0);
+ memcpy(msg, kex1, sizeof(*kex1)), msg += sizeof(*kex1);
+ memcpy(msg, s->label, s->labellen);
}
// Send a SIGnature record, containing an Ed25519 signature over both KEX records.
static bool send_sig(sptps_t *s) {
- size_t keylen = ECDH_SIZE;
- size_t siglen = ecdsa_size(s->mykey);
-
// Concatenate both KEX messages, plus tag indicating if it is from the connection originator, plus label
- const size_t msglen = (1 + 32 + keylen) * 2 + 1 + s->labellen;
+ size_t msglen = sigmsg_len(s->labellen);
uint8_t *msg = alloca(msglen);
- uint8_t *sig = alloca(siglen);
-
- msg[0] = s->initiator;
- memcpy(msg + 1, s->mykex, 1 + 32 + keylen);
- memcpy(msg + 1 + 33 + keylen, s->hiskex, 1 + 32 + keylen);
- memcpy(msg + 1 + 2 * (33 + keylen), s->label, s->labellen);
+ fill_msg(msg, s->initiator, s->mykex, s->hiskex, s);
// Sign the result.
+ size_t siglen = ecdsa_size(s->mykey);
+ uint8_t *sig = alloca(siglen);
+
if(!ecdsa_sign(s->mykey, msg, msglen, sig)) {
return error(s, EINVAL, "Failed to sign SIG record");
}
}
// Allocate memory for key material
- size_t keylen = 2 * CHACHA_POLY1305_KEYLEN;
+ s->key = new_sptps_key();
- s->key = realloc(s->key, keylen);
+ // Create the HMAC seed, which is "key expansion" + session label + server nonce + client nonce
+ const size_t msglen = sizeof("key expansion") - 1;
+ const size_t seedlen = msglen + s->labellen + ECDH_SIZE * 2;
+ uint8_t *seed = alloca(seedlen);
- if(!s->key) {
- return error(s, errno, strerror(errno));
- }
+ uint8_t *ptr = seed;
+ memcpy(ptr, "key expansion", msglen);
+ ptr += msglen;
- // Create the HMAC seed, which is "key expansion" + session label + server nonce + client nonce
- uint8_t *seed = alloca(s->labellen + 64 + 13);
- memcpy(seed, "key expansion", 13);
+ memcpy(ptr, (s->initiator ? s->mykex : s->hiskex)->nonce, ECDH_SIZE);
+ ptr += ECDH_SIZE;
- if(s->initiator) {
- memcpy(seed + 13, s->mykex + 1, 32);
- memcpy(seed + 45, s->hiskex + 1, 32);
- } else {
- memcpy(seed + 13, s->hiskex + 1, 32);
- memcpy(seed + 45, s->mykex + 1, 32);
- }
+ memcpy(ptr, (s->initiator ? s->hiskex : s->mykex)->nonce, ECDH_SIZE);
+ ptr += ECDH_SIZE;
- memcpy(seed + 77, s->label, s->labellen);
+ memcpy(ptr, 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, seedlen, s->key->both, sizeof(sptps_key_t))) {
return error(s, EINVAL, "Failed to generate key material");
}
return error(s, EIO, "Invalid ACK record length");
}
- if(s->initiator) {
- 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)) {
- return error(s, EINVAL, "Failed to set counter");
- }
+ uint8_t *key = s->initiator ? s->key->key0 : s->key->key1;
+
+ if(!chacha_poly1305_set_key(s->incipher, key)) {
+ return error(s, EINVAL, "Failed to set counter");
}
- free(s->key);
+ free_sptps_key(s->key);
s->key = NULL;
s->instate = true;
// Receive a Key EXchange record, respond by sending a SIG record.
static bool receive_kex(sptps_t *s, const uint8_t *data, uint16_t len) {
// Verify length of the HELLO record
- if(len != 1 + 32 + ECDH_SIZE) {
+ if(len != sizeof(sptps_kex_t)) {
return error(s, EIO, "Invalid KEX record length");
}
- // Ignore version number for now.
+ if(*data != SPTPS_VERSION) {
+ return error(s, EINVAL, "Received incorrect version %d", *data);
+ }
// Make a copy of the KEX message, send_sig() and receive_sig() need it
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) {
- return error(s, errno, strerror(errno));
- }
-
- memcpy(s->hiskex, data, len);
+ s->hiskex = new_sptps_kex();
+ memcpy(s->hiskex, data, sizeof(sptps_kex_t));
if(s->initiator) {
return send_sig(s);
// Receive a SIGnature record, verify it, if it passed, compute the shared secret and calculate the session keys.
static bool receive_sig(sptps_t *s, const uint8_t *data, uint16_t len) {
- size_t keylen = ECDH_SIZE;
- size_t siglen = ecdsa_size(s->hiskey);
-
// Verify length of KEX record.
- if(len != siglen) {
+ if(len != ecdsa_size(s->hiskey)) {
return error(s, EIO, "Invalid KEX record length");
}
// Concatenate both KEX messages, plus tag indicating if it is from the connection originator
- const size_t msglen = (1 + 32 + keylen) * 2 + 1 + s->labellen;
+ const size_t msglen = sigmsg_len(s->labellen);
uint8_t *msg = alloca(msglen);
-
- msg[0] = !s->initiator;
- memcpy(msg + 1, s->hiskex, 1 + 32 + keylen);
- memcpy(msg + 1 + 33 + keylen, s->mykex, 1 + 32 + keylen);
- memcpy(msg + 1 + 2 * (33 + keylen), s->label, s->labellen);
+ fill_msg(msg, !s->initiator, s->hiskex, s->mykex, s);
// Verify signature.
if(!ecdsa_verify(s->hiskey, msg, msglen, data)) {
// Compute shared secret.
uint8_t shared[ECDH_SHARED_SIZE];
- if(!ecdh_compute_shared(s->ecdh, s->hiskex + 1 + 32, shared)) {
+ if(!ecdh_compute_shared(s->ecdh, s->hiskex->pubkey, shared)) {
+ memzero(shared, sizeof(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))) {
+ bool generated = generate_key_material(s, shared, sizeof(shared));
+ memzero(shared, sizeof(shared));
+
+ if(!generated) {
return false;
}
return false;
}
- free(s->mykex);
- free(s->hiskex);
-
+ free_sptps_kex(s->mykex);
s->mykex = NULL;
+
+ free_sptps_kex(s->hiskex);
s->hiskex = NULL;
// Send cipher change record
}
// 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)) {
- return error(s, EINVAL, "Failed to set key");
- }
- } else {
- if(!chacha_poly1305_set_key(s->outcipher, s->key)) {
- return error(s, EINVAL, "Failed to set key");
- }
+ uint8_t *key = s->initiator ? s->key->key1 : s->key->key0;
+
+ if(!chacha_poly1305_set_key(s->outcipher, key)) {
+ return error(s, EINVAL, "Failed to set key");
}
return true;
chacha_poly1305_exit(s->outcipher);
ecdh_free(s->ecdh);
free(s->inbuf);
- free(s->mykex);
- free(s->hiskex);
- free(s->key);
+ free_sptps_kex(s->mykex);
+ free_sptps_kex(s->hiskex);
+ free_sptps_key(s->key);
free(s->label);
free(s->late);
memset(s, 0, sizeof(*s));
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