/* * SSL session cache implementation * * Copyright The Mbed TLS Contributors * SPDX-License-Identifier: Apache-2.0 * * Licensed under the Apache License, Version 2.0 (the "License"); you may * not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /* * These session callbacks use a simple chained list * to store and retrieve the session information. */ #include "common.h" #if defined(MBEDTLS_SSL_CACHE_C) #include "mbedtls/platform.h" #include "mbedtls/ssl_cache.h" #include "mbedtls/ssl_internal.h" #include <string.h> void mbedtls_ssl_cache_init(mbedtls_ssl_cache_context *cache) { memset(cache, 0, sizeof(mbedtls_ssl_cache_context)); cache->timeout = MBEDTLS_SSL_CACHE_DEFAULT_TIMEOUT; cache->max_entries = MBEDTLS_SSL_CACHE_DEFAULT_MAX_ENTRIES; #if defined(MBEDTLS_THREADING_C) mbedtls_mutex_init(&cache->mutex); #endif } int mbedtls_ssl_cache_get(void *data, mbedtls_ssl_session *session) { int ret = 1; #if defined(MBEDTLS_HAVE_TIME) mbedtls_time_t t = mbedtls_time(NULL); #endif mbedtls_ssl_cache_context *cache = (mbedtls_ssl_cache_context *) data; mbedtls_ssl_cache_entry *cur, *entry; #if defined(MBEDTLS_THREADING_C) if (mbedtls_mutex_lock(&cache->mutex) != 0) { return 1; } #endif cur = cache->chain; entry = NULL; while (cur != NULL) { entry = cur; cur = cur->next; #if defined(MBEDTLS_HAVE_TIME) if (cache->timeout != 0 && (int) (t - entry->timestamp) > cache->timeout) { continue; } #endif if (session->id_len != entry->session.id_len || memcmp(session->id, entry->session.id, entry->session.id_len) != 0) { continue; } ret = mbedtls_ssl_session_copy(session, &entry->session); if (ret != 0) { ret = 1; goto exit; } #if defined(MBEDTLS_X509_CRT_PARSE_C) && \ defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE) /* * Restore peer certificate (without rest of the original chain) */ if (entry->peer_cert.p != NULL) { /* `session->peer_cert` is NULL after the call to * mbedtls_ssl_session_copy(), because cache entries * have the `peer_cert` field set to NULL. */ if ((session->peer_cert = mbedtls_calloc(1, sizeof(mbedtls_x509_crt))) == NULL) { ret = 1; goto exit; } mbedtls_x509_crt_init(session->peer_cert); if (mbedtls_x509_crt_parse(session->peer_cert, entry->peer_cert.p, entry->peer_cert.len) != 0) { mbedtls_free(session->peer_cert); session->peer_cert = NULL; ret = 1; goto exit; } } #endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */ ret = 0; goto exit; } exit: #if defined(MBEDTLS_THREADING_C) if (mbedtls_mutex_unlock(&cache->mutex) != 0) { ret = 1; } #endif return ret; } int mbedtls_ssl_cache_set(void *data, const mbedtls_ssl_session *session) { int ret = 1; #if defined(MBEDTLS_HAVE_TIME) mbedtls_time_t t = mbedtls_time(NULL), oldest = 0; mbedtls_ssl_cache_entry *old = NULL; #endif mbedtls_ssl_cache_context *cache = (mbedtls_ssl_cache_context *) data; mbedtls_ssl_cache_entry *cur, *prv; int count = 0; #if defined(MBEDTLS_THREADING_C) if ((ret = mbedtls_mutex_lock(&cache->mutex)) != 0) { return ret; } #endif cur = cache->chain; prv = NULL; while (cur != NULL) { count++; #if defined(MBEDTLS_HAVE_TIME) if (cache->timeout != 0 && (int) (t - cur->timestamp) > cache->timeout) { cur->timestamp = t; break; /* expired, reuse this slot, update timestamp */ } #endif if (memcmp(session->id, cur->session.id, cur->session.id_len) == 0) { break; /* client reconnected, keep timestamp for session id */ } #if defined(MBEDTLS_HAVE_TIME) if (oldest == 0 || cur->timestamp < oldest) { oldest = cur->timestamp; old = cur; } #endif prv = cur; cur = cur->next; } if (cur == NULL) { #if defined(MBEDTLS_HAVE_TIME) /* * Reuse oldest entry if max_entries reached */ if (count >= cache->max_entries) { if (old == NULL) { ret = 1; goto exit; } cur = old; } #else /* MBEDTLS_HAVE_TIME */ /* * Reuse first entry in chain if max_entries reached, * but move to last place */ if (count >= cache->max_entries) { if (cache->chain == NULL) { ret = 1; goto exit; } cur = cache->chain; cache->chain = cur->next; cur->next = NULL; prv->next = cur; } #endif /* MBEDTLS_HAVE_TIME */ else { /* * max_entries not reached, create new entry */ cur = mbedtls_calloc(1, sizeof(mbedtls_ssl_cache_entry)); if (cur == NULL) { ret = 1; goto exit; } if (prv == NULL) { cache->chain = cur; } else { prv->next = cur; } } #if defined(MBEDTLS_HAVE_TIME) cur->timestamp = t; #endif } #if defined(MBEDTLS_X509_CRT_PARSE_C) && \ defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE) /* * If we're reusing an entry, free its certificate first */ if (cur->peer_cert.p != NULL) { mbedtls_free(cur->peer_cert.p); memset(&cur->peer_cert, 0, sizeof(mbedtls_x509_buf)); } #endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */ /* Copy the entire session; this temporarily makes a copy of the * X.509 CRT structure even though we only want to store the raw CRT. * This inefficiency will go away as soon as we implement on-demand * parsing of CRTs, in which case there's no need for the `peer_cert` * field anymore in the first place, and we're done after this call. */ ret = mbedtls_ssl_session_copy(&cur->session, session); if (ret != 0) { ret = 1; goto exit; } #if defined(MBEDTLS_X509_CRT_PARSE_C) && \ defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE) /* If present, free the X.509 structure and only store the raw CRT data. */ if (cur->session.peer_cert != NULL) { cur->peer_cert.p = mbedtls_calloc(1, cur->session.peer_cert->raw.len); if (cur->peer_cert.p == NULL) { ret = 1; goto exit; } memcpy(cur->peer_cert.p, cur->session.peer_cert->raw.p, cur->session.peer_cert->raw.len); cur->peer_cert.len = session->peer_cert->raw.len; mbedtls_x509_crt_free(cur->session.peer_cert); mbedtls_free(cur->session.peer_cert); cur->session.peer_cert = NULL; } #endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */ ret = 0; exit: #if defined(MBEDTLS_THREADING_C) if (mbedtls_mutex_unlock(&cache->mutex) != 0) { ret = 1; } #endif return ret; } #if defined(MBEDTLS_HAVE_TIME) void mbedtls_ssl_cache_set_timeout(mbedtls_ssl_cache_context *cache, int timeout) { if (timeout < 0) { timeout = 0; } cache->timeout = timeout; } #endif /* MBEDTLS_HAVE_TIME */ void mbedtls_ssl_cache_set_max_entries(mbedtls_ssl_cache_context *cache, int max) { if (max < 0) { max = 0; } cache->max_entries = max; } void mbedtls_ssl_cache_free(mbedtls_ssl_cache_context *cache) { mbedtls_ssl_cache_entry *cur, *prv; cur = cache->chain; while (cur != NULL) { prv = cur; cur = cur->next; mbedtls_ssl_session_free(&prv->session); #if defined(MBEDTLS_X509_CRT_PARSE_C) && \ defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE) mbedtls_free(prv->peer_cert.p); #endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */ mbedtls_free(prv); } #if defined(MBEDTLS_THREADING_C) mbedtls_mutex_free(&cache->mutex); #endif cache->chain = NULL; } #endif /* MBEDTLS_SSL_CACHE_C */