/*-
* ssl_get_prev attempts to find an SSL_SESSION to be used to resume this
* connection. It is only called by servers.
*
* hello: The parsed ClientHello data
*
* Returns:
* -1: fatal error
* 0: no session found
* 1: a session may have been found.
*
* Side effects:
* - If a session is found then s->session is pointed at it (after freeing an
* existing session if need be) and s->verify_result is set from the session.
* - Both for new and resumed sessions, s->ext.ticket_expected is set to 1
* if the server should issue a new session ticket (to 0 otherwise).
*/
int ssl_get_prev_session(SSL *s, CLIENTHELLO_MSG *hello, int *al)
{
/* This is used only by servers. */
SSL_SESSION *ret = NULL;
int fatal = 0;
int try_session_cache = 0;
TICKET_RETURN r;
if (SSL_IS_TLS13(s)) {
if (!tls_parse_extension(s, TLSEXT_IDX_psk_kex_modes,
SSL_EXT_CLIENT_HELLO, hello->pre_proc_exts,
NULL, 0, al)
|| !tls_parse_extension(s, TLSEXT_IDX_psk, SSL_EXT_CLIENT_HELLO,
hello->pre_proc_exts, NULL, 0, al))
return -1;
ret = s->session;
} else {
/* sets s->ext.ticket_expected */
r = tls_get_ticket_from_client(s, hello, &ret);
switch (r) {
case TICKET_FATAL_ERR_MALLOC:
case TICKET_FATAL_ERR_OTHER:
fatal = 1;
goto err;
case TICKET_NONE:
case TICKET_EMPTY:
try_session_cache = 1;
break;
case TICKET_NO_DECRYPT:
case TICKET_SUCCESS:
case TICKET_SUCCESS_RENEW:
break;
}
}
if (try_session_cache &&
ret == NULL &&
!(s->session_ctx->session_cache_mode &
SSL_SESS_CACHE_NO_INTERNAL_LOOKUP)) {
SSL_SESSION data;
data.ssl_version = s->version;
memcpy(data.session_id, hello->session_id, hello->session_id_len);
data.session_id_length = hello->session_id_len;
CRYPTO_THREAD_read_lock(s->session_ctx->lock);
ret = lh_SSL_SESSION_retrieve(s->session_ctx->sessions, &data);
if (ret != NULL) {
/* don't allow other threads to steal it: */
SSL_SESSION_up_ref(ret);
}
CRYPTO_THREAD_unlock(s->session_ctx->lock);
if (ret == NULL)
s->session_ctx->stats.sess_miss++;
}
if (try_session_cache &&
ret == NULL && s->session_ctx->get_session_cb != NULL) {
int copy = 1;
ret = s->session_ctx->get_session_cb(s, hello->session_id,
hello->session_id_len,
©);
if (ret != NULL) {
s->session_ctx->stats.sess_cb_hit++;
/*
* Increment reference count now if the session callback asks us
* to do so (note that if the session structures returned by the
* callback are shared between threads, it must handle the
* reference count itself [i.e. copy == 0], or things won't be
* thread-safe).
*/
if (copy)
SSL_SESSION_up_ref(ret);
/*
* Add the externally cached session to the internal cache as
* well if and only if we are supposed to.
*/
if (!
(s->session_ctx->session_cache_mode &
SSL_SESS_CACHE_NO_INTERNAL_STORE)) {
/*
* The following should not return 1, otherwise, things are
* very strange
*/
if (SSL_CTX_add_session(s->session_ctx, ret))
goto err;
}
}
}
if (ret == NULL)
goto err;
/* Now ret is non-NULL and we own one of its reference counts. */
/* Check TLS version consistency */
if (ret->ssl_version != s->version)
goto err;
if (ret->sid_ctx_length != s->sid_ctx_length
|| memcmp(ret->sid_ctx, s->sid_ctx, ret->sid_ctx_length)) {
/*
* We have the session requested by the client, but we don't want to
* use it in this context.
*/
goto err; /* treat like cache miss */
}
if ((s->verify_mode & SSL_VERIFY_PEER) && s->sid_ctx_length == 0) {
/*
* We can't be sure if this session is being used out of context,
* which is especially important for SSL_VERIFY_PEER. The application
* should have used SSL[_CTX]_set_session_id_context. For this error
* case, we generate an error instead of treating the event like a
* cache miss (otherwise it would be easy for applications to
* effectively disable the session cache by accident without anyone
* noticing).
*/
SSLerr(SSL_F_SSL_GET_PREV_SESSION,
SSL_R_SESSION_ID_CONTEXT_UNINITIALIZED);
fatal = 1;
goto err;
}
if (ret->timeout < (long)(time(NULL) - ret->time)) { /* timeout */
s->session_ctx->stats.sess_timeout++;
if (try_session_cache) {
/* session was from the cache, so remove it */
SSL_CTX_remove_session(s->session_ctx, ret);
}
goto err;
}
/* Check extended master secret extension consistency */
if (ret->flags & SSL_SESS_FLAG_EXTMS) {
/* If old session includes extms, but new does not: abort handshake */
if (!(s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS)) {
SSLerr(SSL_F_SSL_GET_PREV_SESSION, SSL_R_INCONSISTENT_EXTMS);
ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
fatal = 1;
goto err;
}
} else if (s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS) {
/* If new session includes extms, but old does not: do not resume */
goto err;
}
if (!SSL_IS_TLS13(s)) {
/* We already did this for TLS1.3 */
SSL_SESSION_free(s->session);
s->session = ret;
}
s->session_ctx->stats.sess_hit++;
s->verify_result = s->session->verify_result;
return 1;
err:
if (ret != NULL) {
SSL_SESSION_free(ret);
/* In TLSv1.3 s->session was already set to ret, so we NULL it out */
if (SSL_IS_TLS13(s))
s->session = NULL;
if (!try_session_cache) {
/*
* The session was from a ticket, so we should issue a ticket for
* the new session
*/
s->ext.ticket_expected = 1;
}
}
if (fatal) {
*al = SSL_AD_INTERNAL_ERROR;
return -1;
}
return 0;
}
/*-
* ssl_get_prev attempts to find an SSL_SESSION to be used to resume this
* connection. It is only called by servers.
*
* hello: The parsed ClientHello data
*
* Returns:
* -1: fatal error
* 0: no session found
* 1: a session may have been found.
*
* Side effects:
* - If a session is found then s->session is pointed at it (after freeing an
* existing session if need be) and s->verify_result is set from the session.
* - Both for new and resumed sessions, s->ext.ticket_expected is set to 1
* if the server should issue a new session ticket (to 0 otherwise).
*/
int ssl_get_prev_session(SSL *s, CLIENTHELLO_MSG *hello)
{
/* This is used only by servers. */
SSL_SESSION *ret = NULL;
int fatal = 0;
int try_session_cache = 0;
SSL_TICKET_STATUS r;
if (SSL_IS_TLS13(s)) {
/*
* By default we will send a new ticket. This can be overridden in the
* ticket processing.
*/
s->ext.ticket_expected = 1;
if (!tls_parse_extension(s, TLSEXT_IDX_psk_kex_modes,
SSL_EXT_CLIENT_HELLO, hello->pre_proc_exts,
NULL, 0)
|| !tls_parse_extension(s, TLSEXT_IDX_psk, SSL_EXT_CLIENT_HELLO,
hello->pre_proc_exts, NULL, 0))
return -1;
ret = s->session;
} else {
/* sets s->ext.ticket_expected */
r = tls_get_ticket_from_client(s, hello, &ret);
switch (r) {
case SSL_TICKET_FATAL_ERR_MALLOC:
case SSL_TICKET_FATAL_ERR_OTHER:
fatal = 1;
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL_GET_PREV_SESSION,
ERR_R_INTERNAL_ERROR);
goto err;
case SSL_TICKET_NONE:
case SSL_TICKET_EMPTY:
if (hello->session_id_len > 0) {
try_session_cache = 1;
ret = lookup_sess_in_cache(s, hello->session_id,
hello->session_id_len);
}
break;
case SSL_TICKET_NO_DECRYPT:
case SSL_TICKET_SUCCESS:
case SSL_TICKET_SUCCESS_RENEW:
break;
}
}
if (ret == NULL)
goto err;
/* Now ret is non-NULL and we own one of its reference counts. */
/* Check TLS version consistency */
if (ret->ssl_version != s->version)
goto err;
if (ret->sid_ctx_length != s->sid_ctx_length
|| memcmp(ret->sid_ctx, s->sid_ctx, ret->sid_ctx_length)) {
/*
* We have the session requested by the client, but we don't want to
* use it in this context.
*/
goto err; /* treat like cache miss */
}
if ((s->verify_mode & SSL_VERIFY_PEER) && s->sid_ctx_length == 0) {
/*
* We can't be sure if this session is being used out of context,
* which is especially important for SSL_VERIFY_PEER. The application
* should have used SSL[_CTX]_set_session_id_context. For this error
* case, we generate an error instead of treating the event like a
* cache miss (otherwise it would be easy for applications to
* effectively disable the session cache by accident without anyone
* noticing).
*/
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_SSL_GET_PREV_SESSION,
SSL_R_SESSION_ID_CONTEXT_UNINITIALIZED);
fatal = 1;
goto err;
}
if (ret->timeout < (long)(time(NULL) - ret->time)) { /* timeout */
tsan_counter(&s->session_ctx->stats.sess_timeout);
if (try_session_cache) {
/* session was from the cache, so remove it */
SSL_CTX_remove_session(s->session_ctx, ret);
}
goto err;
}
/* Check extended master secret extension consistency */
if (ret->flags & SSL_SESS_FLAG_EXTMS) {
/* If old session includes extms, but new does not: abort handshake */
if (!(s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS)) {
SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_SSL_GET_PREV_SESSION,
SSL_R_INCONSISTENT_EXTMS);
fatal = 1;
goto err;
}
} else if (s->s3->flags & TLS1_FLAGS_RECEIVED_EXTMS) {
/* If new session includes extms, but old does not: do not resume */
goto err;
}
if (!SSL_IS_TLS13(s)) {
/* We already did this for TLS1.3 */
SSL_SESSION_free(s->session);
s->session = ret;
}
tsan_counter(&s->session_ctx->stats.sess_hit);
s->verify_result = s->session->verify_result;
return 1;
err:
if (ret != NULL) {
SSL_SESSION_free(ret);
/* In TLSv1.3 s->session was already set to ret, so we NULL it out */
if (SSL_IS_TLS13(s))
s->session = NULL;
if (!try_session_cache) {
/*
* The session was from a ticket, so we should issue a ticket for
* the new session
*/
s->ext.ticket_expected = 1;
}
}
if (fatal)
return -1;
return 0;
}
