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Use accessor functions for client_random/server_random/master_key

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If OpenSSL accepts my patch to introduce these functions, they'll
be a way to help Tor work with OpenSSL 1.1.
This commit is contained in:
Nick Mathewson 2015-05-26 12:09:53 -04:00
parent 9537596398
commit f90a704f12
1 changed files with 83 additions and 11 deletions
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94
src/common/tortls.c
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@ -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;
}