/*
sptps.c -- Simple Peer-to-Peer Security
- Copyright (C) 2011-2014 Guus Sliepen <guus@tinc-vpn.org>,
+ Copyright (C) 2011-2021 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
#include "system.h"
-#include "chacha-poly1305/chacha-poly1305.h"
-#include "crypto.h"
+#include "chacha-poly1305/chachapoly.h"
#include "ecdh.h"
#include "ecdsa.h"
-#include "logger.h"
#include "prf.h"
#include "sptps.h"
+#include "random.h"
+#include "xalloc.h"
+
+#ifdef HAVE_OPENSSL
+#include <openssl/evp.h>
+#endif
+
+#define CIPHER_KEYLEN 64
unsigned int sptps_replaywin = 16;
*/
void sptps_log_quiet(sptps_t *s, int s_errno, const char *format, va_list ap) {
+ (void)s;
+ (void)s_errno;
+ (void)format;
+ (void)ap;
}
void sptps_log_stderr(sptps_t *s, int s_errno, const char *format, va_list ap) {
+ (void)s;
+ (void)s_errno;
+
vfprintf(stderr, format, ap);
fputc('\n', stderr);
}
void (*sptps_log)(sptps_t *s, int s_errno, const char *format, va_list ap) = sptps_log_stderr;
// Log an error message.
+static bool error(sptps_t *s, int s_errno, const char *format, ...) ATTR_FORMAT(printf, 3, 4);
static bool error(sptps_t *s, int s_errno, const char *format, ...) {
+ (void)s;
+ (void)s_errno;
+
if(format) {
va_list ap;
va_start(ap, format);
return false;
}
+static void warning(sptps_t *s, const char *format, ...) ATTR_FORMAT(printf, 2, 3);
static void warning(sptps_t *s, const char *format, ...) {
va_list ap;
va_start(ap, format);
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));
+}
+
+static bool cipher_init(uint8_t suite, void **ctx, const sptps_key_t *keys, bool key_half) {
+ const uint8_t *key = key_half ? keys->key1 : keys->key0;
+
+ switch(suite) {
+#ifndef HAVE_OPENSSL
+
+ case SPTPS_CHACHA_POLY1305:
+ *ctx = malloc(sizeof(struct chachapoly_ctx));
+ return *ctx && chachapoly_init(*ctx, key, 256) == CHACHAPOLY_OK;
+
+#else
+
+ case SPTPS_CHACHA_POLY1305:
+#ifdef EVP_F_EVP_AEAD_CTX_INIT
+ *ctx = malloc(sizeof(EVP_AEAD_CTX));
+
+ return *ctx && EVP_AEAD_CTX_init(*ctx, EVP_aead_chacha20_poly1305(), key + (key_half ? CIPHER_KEYLEN : 0), 32, 16, NULL);
+#else
+ *ctx = EVP_CIPHER_CTX_new();
+
+ return *ctx
+ && EVP_EncryptInit_ex(*ctx, EVP_chacha20_poly1305(), NULL, NULL, NULL)
+ && EVP_CIPHER_CTX_ctrl(*ctx, EVP_CTRL_GCM_SET_IVLEN, 12, NULL)
+ && EVP_EncryptInit_ex(*ctx, NULL, NULL, key, key + 32);
+#endif
+
+ case SPTPS_AES256_GCM:
+ *ctx = EVP_CIPHER_CTX_new();
+
+ return *ctx
+ && EVP_EncryptInit_ex(*ctx, EVP_aes_256_gcm(), NULL, NULL, NULL)
+ && EVP_CIPHER_CTX_ctrl(*ctx, EVP_CTRL_GCM_SET_IVLEN, 12, NULL)
+ && EVP_EncryptInit_ex(*ctx, NULL, NULL, key, key + 32);
+#endif
+
+ default:
+ return false;
+ }
+}
+
+static void cipher_exit(uint8_t suite, void *ctx) {
+ switch(suite) {
+#ifndef HAVE_OPENSSL
+
+ case SPTPS_CHACHA_POLY1305:
+ free(ctx);
+ break;
+
+#else
+
+ case SPTPS_CHACHA_POLY1305:
+#ifdef EVP_F_EVP_AEAD_CTX_INIT
+ EVP_AEAD_CTX_cleanup(ctx);
+ free(ctx);
+ break;
+#endif
+
+ case SPTPS_AES256_GCM:
+ EVP_CIPHER_CTX_free(ctx);
+ break;
+#endif
+
+ default:
+ break;
+ }
+}
+
+static bool cipher_encrypt(uint8_t suite, void *ctx, uint32_t seqno, const uint8_t *in, size_t inlen, uint8_t *out, size_t *outlen) {
+ switch(suite) {
+#ifndef HAVE_OPENSSL
+
+ case SPTPS_CHACHA_POLY1305: {
+ if(chachapoly_crypt(ctx, nonce, (void *)in, inlen, out, out + inlen, 16, 1) != CHACHAPOLY_OK) {
+ return false;
+ }
+
+ if(outlen) {
+ *outlen = inlen + 16;
+ }
+
+ return true;
+ }
+
+#else
+
+ case SPTPS_CHACHA_POLY1305:
+#ifdef EVP_F_EVP_AEAD_CTX_INIT
+ {
+ size_t outlen1;
+
+ if(!EVP_AEAD_CTX_seal(ctx, out, &outlen1, inlen + 16, nonce, sizeof(nonce), in, inlen, NULL, 0)) {
+ return false;
+ }
+
+ if(outlen) {
+ *outlen = outlen1;
+ }
+
+ return true;
+ }
+
+#endif
+
+ case SPTPS_AES256_GCM: {
+ uint8_t nonce[12] = {seqno, seqno >> 8, seqno >> 16, seqno >> 24};
+
+ if(!EVP_EncryptInit_ex(ctx, NULL, NULL, NULL, nonce)) {
+ return false;
+ }
+
+ int outlen1 = 0, outlen2 = 0;
+
+ if(!EVP_EncryptUpdate(ctx, out, &outlen1, in, (int)inlen)) {
+ return false;
+ }
+
+ if(!EVP_EncryptFinal_ex(ctx, out + outlen1, &outlen2)) {
+ return false;
+ }
+
+ outlen1 += outlen2;
+
+ if(!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, 16, out + outlen1)) {
+ return false;
+ }
+
+ outlen1 += 16;
+
+ if(outlen) {
+ *outlen = outlen1;
+ }
+
+ return true;
+ }
+
+#endif
+
+ default:
+ return false;
+ }
+}
+
+static bool cipher_decrypt(uint8_t suite, void *ctx, uint32_t seqno, const uint8_t *in, size_t inlen, uint8_t *out, size_t *outlen) {
+ if(inlen < 16) {
+ return false;
+ }
+
+ inlen -= 16;
+
+ switch(suite) {
+#ifndef HAVE_OPENSSL
+
+ case SPTPS_CHACHA_POLY1305:
+ if(chachapoly_crypt(ctx, nonce, (void *)in, inlen, out, (void *)(in + inlen), 16, 0) != CHACHAPOLY_OK) {
+ return false;
+ }
+
+ if(outlen) {
+ *outlen = inlen;
+ }
+
+ return true;
+
+#else
+
+ case SPTPS_CHACHA_POLY1305:
+#ifdef EVP_F_EVP_AEAD_CTX_INIT
+ {
+ size_t outlen1;
+
+ if(!EVP_AEAD_CTX_open(ctx, out, &outlen1, inlen, nonce, sizeof(nonce), in, inlen + 16, NULL, 0)) {
+ return false;
+ }
+
+ if(outlen) {
+ *outlen = outlen1;
+ }
+
+ return true;
+ }
+
+#endif
+
+ case SPTPS_AES256_GCM: {
+ uint8_t nonce[12] = {seqno, seqno >> 8, seqno >> 16, seqno >> 24};
+
+ if(!EVP_DecryptInit_ex(ctx, NULL, NULL, NULL, nonce)) {
+ return false;
+ }
+
+ int outlen1 = 0, outlen2 = 0;
+
+ if(!EVP_DecryptUpdate(ctx, out, &outlen1, in, (int)inlen)) {
+ return false;
+ }
+
+ if(!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, 16, (void *)(in + inlen))) {
+ return false;
+ }
+
+ if(!EVP_DecryptFinal_ex(ctx, out + outlen1, &outlen2)) {
+ return false;
+ }
+
+ if(outlen) {
+ *outlen = outlen1 + outlen2;
+ }
+
+ return true;
+ }
+
+#endif
+
+ default:
+ return false;
+ }
+}
+
// 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) {
- char buffer[len + 21UL];
-
+ uint8_t *buffer = alloca(len + SPTPS_DATAGRAM_OVERHEAD);
// Create header with sequence number, length and record type
uint32_t seqno = s->outseqno++;
- uint32_t netseqno = ntohl(seqno);
- memcpy(buffer, &netseqno, 4);
+ memcpy(buffer, &seqno, 4);
buffer[4] = type;
memcpy(buffer + 5, data, len);
if(s->outstate) {
// If first handshake has finished, encrypt and HMAC
- chacha_poly1305_encrypt(s->outcipher, seqno, buffer + 4, len + 1, buffer + 4, NULL);
- return s->send_data(s->handle, type, buffer, len + 21UL);
+ if(!cipher_encrypt(s->cipher_suite, s->outcipher, seqno, buffer + 4, len + 1, buffer + 4, NULL)) {
+ return error(s, EINVAL, "Failed to encrypt message");
+ }
+
+ return s->send_data(s->handle, type, buffer, len + SPTPS_DATAGRAM_OVERHEAD);
} else {
// Otherwise send as plaintext
- return s->send_data(s->handle, type, buffer, len + 5UL);
+ return s->send_data(s->handle, type, buffer, len + SPTPS_DATAGRAM_HEADER);
}
}
// 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];
+ uint8_t *buffer = alloca(len + SPTPS_OVERHEAD);
// Create header with sequence number, length and record type
uint32_t seqno = s->outseqno++;
- uint16_t netlen = htons(len);
+ uint16_t netlen = len;
memcpy(buffer, &netlen, 2);
buffer[2] = type;
if(s->outstate) {
// If first handshake has finished, encrypt and HMAC
- chacha_poly1305_encrypt(s->outcipher, seqno, buffer + 2, len + 1, buffer + 2, NULL);
- return s->send_data(s->handle, type, buffer, len + 19UL);
+ if(!cipher_encrypt(s->cipher_suite, s->outcipher, seqno, buffer + 2, len + 1, buffer + 2, NULL)) {
+ return error(s, EINVAL, "Failed to encrypt message");
+ }
+
+ return s->send_data(s->handle, type, buffer, len + SPTPS_OVERHEAD);
} else {
// Otherwise send as plaintext
- return s->send_data(s->handle, type, buffer, len + 3UL);
+ return s->send_data(s->handle, type, buffer, len + SPTPS_HEADER);
}
}
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);
}
// 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)
+ 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;
+ s->mykex->preferred_suite = s->preferred_suite;
+ s->mykex->cipher_suites = s->cipher_suites;
// 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, sizeof(sptps_kex_t));
+}
+
+static size_t sigmsg_len(size_t labellen) {
+ return 1 + 2 * sizeof(sptps_kex_t) + labellen;
+}
- return send_record_priv(s, SPTPS_HANDSHAKE, s->mykex, 1 + 32 + keylen);
+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
- char msg[(1 + 32 + keylen) * 2 + 1 + s->labellen];
- char sig[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);
+ size_t msglen = sigmsg_len(s->labellen);
+ uint8_t *msg = alloca(msglen);
+ fill_msg(msg, s->initiator, s->mykex, s->hiskex, s);
// Sign the result.
- if(!ecdsa_sign(s->mykey, msg, sizeof msg, sig))
+ 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");
+ }
// Send the SIG exchange record.
- return send_record_priv(s, SPTPS_HANDSHAKE, sig, sizeof sig);
+ return send_record_priv(s, SPTPS_HANDSHAKE, sig, siglen);
}
// Generate key material from the shared secret created from the ECDHE key exchange.
-static bool generate_key_material(sptps_t *s, const char *shared, size_t len) {
- // Initialise cipher and digest structures if necessary
- if(!s->outstate) {
- s->incipher = chacha_poly1305_init();
- s->outcipher = chacha_poly1305_init();
- if(!s->incipher || !s->outcipher)
- return error(s, EINVAL, "Failed to open cipher");
- }
-
+static bool generate_key_material(sptps_t *s, const uint8_t *shared, size_t len) {
// Allocate memory for key material
- size_t keylen = 2 * CHACHA_POLY1305_KEYLEN;
-
- s->key = realloc(s->key, keylen);
- if(!s->key)
- return error(s, errno, strerror(errno));
+ s->key = new_sptps_key();
// Create the HMAC seed, which is "key expansion" + session label + server nonce + client nonce
- char seed[s->labellen + 64 + 13];
- strcpy(seed, "key expansion");
- 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(seed + 77, s->label, s->labellen);
+ const size_t msglen = sizeof("key expansion") - 1;
+ const size_t seedlen = msglen + s->labellen + ECDH_SIZE * 2;
+ uint8_t *seed = alloca(seedlen);
+
+ uint8_t *ptr = seed;
+ memcpy(ptr, "key expansion", msglen);
+ ptr += msglen;
+
+ memcpy(ptr, (s->initiator ? s->mykex : s->hiskex)->nonce, ECDH_SIZE);
+ ptr += ECDH_SIZE;
+
+ memcpy(ptr, (s->initiator ? s->hiskex : s->mykex)->nonce, ECDH_SIZE);
+ ptr += ECDH_SIZE;
+
+ 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 true;
}
}
// Receive an ACKnowledgement record.
-static bool receive_ack(sptps_t *s, const char *data, uint16_t len) {
- if(len)
+static bool receive_ack(sptps_t *s, const uint8_t *data, uint16_t len) {
+ (void)data;
+
+ if(len) {
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");
+ if(!cipher_init(s->cipher_suite, &s->incipher, s->key, s->initiator)) {
+ return error(s, EINVAL, "Failed to initialize cipher");
}
- free(s->key);
+ free_sptps_key(s->key);
s->key = NULL;
s->instate = true;
return true;
}
+static uint8_t select_cipher_suite(uint16_t mask, uint8_t pref1, uint8_t pref2) {
+ // Check if there is a viable preference, if so select the lowest one
+ uint8_t selection = 255;
+
+ if(mask & (1U << pref1)) {
+ selection = pref1;
+ }
+
+ if(pref2 < selection && (mask & (1U << pref2))) {
+ selection = pref2;
+ }
+
+ // Otherwise, select the lowest cipher suite both sides support
+ if(selection == 255) {
+ selection = 0;
+
+ while(!(mask & 1U)) {
+ selection++;
+ mask >>= 1;
+ }
+ }
+
+ return selection;
+}
+
// Receive a Key EXchange record, respond by sending a SIG record.
-static bool receive_kex(sptps_t *s, const char *data, uint16_t len) {
+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);
+ }
+
+ uint16_t suites;
+ memcpy(&suites, data + 2, 2);
+ suites &= s->cipher_suites;
+
+ if(!suites) {
+ return error(s, EIO, "No matching cipher suites");
+ }
+
+ s->cipher_suite = select_cipher_suite(suites, s->preferred_suite, data[1] & 0xf);
// 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)
- return error(s, errno, strerror(errno));
+ }
- memcpy(s->hiskex, data, len);
+ s->hiskex = new_sptps_kex();
+ memcpy(s->hiskex, data, sizeof(sptps_kex_t));
- 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.
-static bool receive_sig(sptps_t *s, const char *data, uint16_t len) {
- size_t keylen = ECDH_SIZE;
- size_t siglen = ecdsa_size(s->hiskey);
-
+static bool receive_sig(sptps_t *s, const uint8_t *data, uint16_t len) {
// 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
- char msg[(1 + 32 + keylen) * 2 + 1 + s->labellen];
-
- 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);
+ const size_t msglen = sigmsg_len(s->labellen);
+ uint8_t *msg = alloca(msglen);
+ fill_msg(msg, !s->initiator, s->hiskex, s->mykex, s);
// Verify signature.
- if(!ecdsa_verify(s->hiskey, msg, sizeof msg, data))
+ if(!ecdsa_verify(s->hiskey, msg, msglen, 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))
+ uint8_t shared[ECDH_SHARED_SIZE];
+
+ 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;
+ }
- free(s->mykex);
- free(s->hiskex);
+ if(!s->initiator && !send_sig(s)) {
+ return false;
+ }
+ free_sptps_kex(s->mykex);
s->mykex = NULL;
+
+ free_sptps_kex(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))
- 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");
+ if(!cipher_init(s->cipher_suite, &s->outcipher, s->key, !s->initiator)) {
+ return error(s, EINVAL, "Failed to initialize cipher");
}
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);
}
// Receive a handshake record.
-static bool receive_handshake(sptps_t *s, const char *data, uint16_t len) {
+static bool receive_handshake(sptps_t *s, const uint8_t *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;
+ }
+
+ // Fall through
+ 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(uint32_t 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)
+bool sptps_verify_datagram(sptps_t *s, const void *vdata, size_t len) {
+ if(!s->instate || len < 21) {
return error(s, EIO, "Received short packet");
+ }
+ const uint8_t *data = vdata;
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;
- return chacha_poly1305_decrypt(s->incipher, seqno, data + 4, len - 4, buffer, &outlen);
+ uint8_t *buffer = alloca(len);
+ return cipher_decrypt(s->cipher_suite, s->incipher, seqno, data + 4, len - 4, buffer, NULL);
}
// 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))
+static bool sptps_receive_data_datagram(sptps_t *s, const uint8_t *data, size_t len) {
+ 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;
+ 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++); len--;
+ 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, len);
}
// Decrypt
- char buffer[len];
+ uint8_t *buffer = alloca(len);
size_t outlen;
- if(!chacha_poly1305_decrypt(s->incipher, seqno, data, len, buffer, &outlen))
+
+ if(!cipher_decrypt(s->cipher_suite, 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[outlen] = 0;
data = buffer;
len = outlen;
- uint8_t type = *(data++); len--;
+ 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, data, len))
+ }
+
+ if(!s->receive_record(s->handle, type, data, len)) {
return false;
+ }
} else if(type == SPTPS_HANDSHAKE) {
- if(!receive_handshake(s, data, len))
+ 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.
-size_t sptps_receive_data(sptps_t *s, const void *data, size_t len) {
+size_t sptps_receive_data(sptps_t *s, const void *vdata, size_t len) {
+ const uint8_t *data = vdata;
size_t total_read = 0;
- if(!s->state)
+ if(!s->state) {
return error(s, EIO, "Invalid session state zero");
+ }
- if(s->datagram)
+ if(s->datagram) {
return sptps_receive_data_datagram(s, data, len) ? len : false;
+ }
// First read the 2 length bytes.
if(s->buflen < 2) {
size_t toread = 2 - s->buflen;
- if(toread > len)
+
+ if(toread > len) {
toread = len;
+ }
memcpy(s->inbuf + s->buflen, data, toread);
data += toread;
// Exit early if we don't have the full length.
- if(s->buflen < 2)
+ if(s->buflen < 2) {
return total_read;
+ }
// Get the length bytes
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));
+ s->inbuf = realloc(s->inbuf, s->reclen + SPTPS_OVERHEAD);
+
+ if(!s->inbuf) {
+ return error(s, errno, "%s", strerror(errno));
+ }
// Exit early if we have no more data to process.
- if(!len)
+ if(!len) {
return total_read;
+ }
}
// Read up to the end of the record.
- size_t toread = s->reclen + (s->instate ? 19UL : 3UL) - s->buflen;
- if(toread > len)
+ size_t toread = s->reclen + (s->instate ? SPTPS_OVERHEAD : SPTPS_HEADER) - s->buflen;
+
+ if(toread > len) {
toread = len;
+ }
memcpy(s->inbuf + s->buflen, data, toread);
total_read += toread;
s->buflen += toread;
- len -= toread;
- data += toread;
// If we don't have a whole record, exit.
- if(s->buflen < s->reclen + (s->instate ? 19UL : 3UL))
+ if(s->buflen < s->reclen + (s->instate ? SPTPS_OVERHEAD : SPTPS_HEADER)) {
return total_read;
+ }
// Update sequence number.
// Check HMAC and decrypt.
if(s->instate) {
- if(!chacha_poly1305_decrypt(s->incipher, seqno, s->inbuf + 2UL, s->reclen + 17UL, s->inbuf + 2UL, NULL))
+ if(!cipher_decrypt(s->cipher_suite, 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;
+ s->inbuf[s->reclen + SPTPS_HEADER] = 0;
uint8_t type = s->inbuf[2];
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, s->inbuf + 3, s->reclen))
+ }
+
+ 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))
+ if(!receive_handshake(s, s->inbuf + 3, s->reclen)) {
return false;
+ }
} else {
return error(s, EIO, "Invalid record type %d", type);
}
}
// 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) {
+bool sptps_start(sptps_t *s, const sptps_params_t *params) {
// Initialise struct sptps
- memset(s, 0, sizeof *s);
+ memset(s, 0, sizeof(*s));
- s->handle = handle;
- s->initiator = initiator;
- s->datagram = datagram;
- s->mykey = mykey;
- s->hiskey = hiskey;
+ s->handle = params->handle;
+ s->initiator = params->initiator;
+ s->datagram = params->datagram;
+ s->mykey = params->mykey;
+ s->hiskey = params->hiskey;
s->replaywin = sptps_replaywin;
+ s->cipher_suites = params->cipher_suites ? params->cipher_suites & SPTPS_ALL_CIPHER_SUITES : SPTPS_ALL_CIPHER_SUITES;
+ s->preferred_suite = params->preferred_suite;
+
if(s->replaywin) {
s->late = malloc(s->replaywin);
- if(!s->late)
- return error(s, errno, strerror(errno));
+
+ if(!s->late) {
+ return error(s, errno, "%s", strerror(errno));
+ }
+
memset(s->late, 0, s->replaywin);
}
- s->label = malloc(labellen);
- if(!s->label)
- return error(s, errno, strerror(errno));
+ s->labellen = params->labellen ? params->labellen : strlen(params->label);
+ s->label = malloc(s->labellen);
+
+ if(!s->label) {
+ return error(s, errno, "%s", strerror(errno));
+ }
+
+ memcpy(s->label, params->label, s->labellen);
- if(!datagram) {
+ if(!s->datagram) {
s->inbuf = malloc(7);
- if(!s->inbuf)
- return error(s, errno, strerror(errno));
+
+ if(!s->inbuf) {
+ return error(s, errno, "%s", strerror(errno));
+ }
+
s->buflen = 0;
}
- memcpy(s->label, label, labellen);
- s->labellen = labellen;
- s->send_data = send_data;
- s->receive_record = receive_record;
+ s->send_data = params->send_data;
+ s->receive_record = params->receive_record;
// Do first KEX immediately
s->state = SPTPS_KEX;
// Stop a SPTPS session.
bool sptps_stop(sptps_t *s) {
// Clean up any resources.
- chacha_poly1305_exit(s->incipher);
- chacha_poly1305_exit(s->outcipher);
+ cipher_exit(s->cipher_suite, s->incipher);
+ cipher_exit(s->cipher_suite, 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);
+ memset(s, 0, sizeof(*s));
return true;
}