commit f90a704f12587ba7585a8a4d31cb6de756bb3868 Author: Nick Mathewson nickm@torproject.org Date: Tue May 26 12:09:53 2015 -0400

Use accessor functions for client_random/server_random/master_key

If OpenSSL accepts my patch to introduce these functions, they'll be a way to help Tor work with OpenSSL 1.1. --- src/common/tortls.c | 94 +++++++++++++++++++++++++++++++++++++++++++++------ 1 file changed, 83 insertions(+), 11 deletions(-)

diff --git a/src/common/tortls.c b/src/common/tortls.c index d4a565c..d80cf42 100644 --- a/src/common/tortls.c +++ b/src/common/tortls.c @@ -2707,6 +2707,46 @@ tor_tls_server_got_renegotiate(tor_tls_t *tls) return tls->got_renegotiate; }

+#ifndef HAVE_SSL_GET_CLIENT_RANDOM +static size_t +SSL_get_client_random(SSL *s, uint8_t *out, size_t len) +{ + if (len == 0) + return SSL3_RANDOM_SIZE; + tor_assert(len == SSL3_RANDOM_SIZE); + tor_assert(s->s3); + memcpy(out, s->s3->client_random, len); + return len; +} +#endif + +#ifndef HAVE_SSL_GET_SERVER_RANDOM +static size_t +SSL_get_server_random(SSL *s, uint8_t *out, size_t len) +{ + if (len == 0) + return SSL3_RANDOM_SIZE; + tor_assert(len == SSL3_RANDOM_SIZE); + tor_assert(s->s3); + memcpy(out, s->s3->server_random, len); + return len; +} +#endif + +#ifndef HAVE_SSL_SESSION_GET_MASTER_KEY +static size_t +SSL_SESSION_get_master_key(SSL_SESSION *s, uint8_t *out, size_t len) +{ + if (len == 0) + return s->master_key_length; + tor_assert(len == (size_t)s->master_key_length); + tor_assert(s->master_key); + memcpy(out, s->master_key, len); + return len; +} +#endif + + /** Set the DIGEST256_LEN buffer at <b>secrets_out</b> to the value used in * the v3 handshake to prove that the client knows the TLS secrets for the * connection <b>tls</b>. Return 0 on success, -1 on failure. @@ -2715,25 +2755,57 @@ int tor_tls_get_tlssecrets(tor_tls_t *tls, uint8_t *secrets_out) { #define TLSSECRET_MAGIC "Tor V3 handshake TLS cross-certification" - char buf[128]; + uint8_t buf[128]; size_t len; + tor_assert(tls); - tor_assert(tls->ssl); - tor_assert(tls->ssl->s3); - tor_assert(tls->ssl->session); + + SSL *const ssl = tls->ssl; + SSL_SESSION *const session = SSL_get_session(ssl); + + tor_assert(ssl); + tor_assert(session); + + const size_t server_random_len = SSL_get_server_random(ssl, NULL, 0); + const size_t client_random_len = SSL_get_client_random(ssl, NULL, 0); + const size_t master_key_len = SSL_SESSION_get_master_key(session, NULL, 0); + + tor_assert(server_random_len); + tor_assert(client_random_len); + tor_assert(master_key_len); + + len = client_random_len + server_random_len + strlen(TLSSECRET_MAGIC) + 1; + tor_assert(len <= sizeof(buf)); + + { + size_t r = SSL_get_client_random(ssl, buf, client_random_len); + tor_assert(r == client_random_len); + } + { + size_t r = SSL_get_server_random(ssl, buf+client_random_len, server_random_len); + tor_assert(r == server_random_len); + } + uint8_t *master_key = tor_malloc_zero(master_key_len); + { + size_t r = SSL_SESSION_get_master_key(session, master_key, master_key_len); + tor_assert(r == master_key_len); + } + + uint8_t *nextbuf = buf + client_random_len + server_random_len; + memcpy(nextbuf, TLSSECRET_MAGIC, strlen(TLSSECRET_MAGIC) + 1); + /* The value is an HMAC, using the TLS master key as the HMAC key, of client_random | server_random | TLSSECRET_MAGIC */ - memcpy(buf + 0, tls->ssl->s3->client_random, 32); - memcpy(buf + 32, tls->ssl->s3->server_random, 32); - memcpy(buf + 64, TLSSECRET_MAGIC, strlen(TLSSECRET_MAGIC) + 1); - len = 64 + strlen(TLSSECRET_MAGIC) + 1; crypto_hmac_sha256((char*)secrets_out, - (char*)tls->ssl->session->master_key, - tls->ssl->session->master_key_length, - buf, len); + (char*)master_key, + master_key_len, + (char*)buf, len); memwipe(buf, 0, sizeof(buf)); + memwipe(master_key, 0, master_key_len); + tor_free(master_key); + return 0; }