| /* |
| * 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) |
| |
| #if defined(MBEDTLS_PLATFORM_C) |
| #include "mbedtls/platform.h" |
| #else |
| #include <stdlib.h> |
| #define mbedtls_calloc calloc |
| #define mbedtls_free free |
| #endif |
| |
| #include "mbedtls/ssl_cache.h" |
| #include "ssl_misc.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 |
| } |
| |
| static int ssl_cache_find_entry( mbedtls_ssl_cache_context *cache, |
| unsigned char const *session_id, |
| size_t session_id_len, |
| mbedtls_ssl_cache_entry **dst ) |
| { |
| int ret = 1; |
| #if defined(MBEDTLS_HAVE_TIME) |
| mbedtls_time_t t = mbedtls_time( NULL ); |
| #endif |
| mbedtls_ssl_cache_entry *cur; |
| |
| for( cur = cache->chain; cur != NULL; cur = cur->next ) |
| { |
| #if defined(MBEDTLS_HAVE_TIME) |
| if( cache->timeout != 0 && |
| (int) ( t - cur->timestamp ) > cache->timeout ) |
| continue; |
| #endif |
| |
| if( session_id_len != cur->session_id_len || |
| memcmp( session_id, cur->session_id, |
| cur->session_id_len ) != 0 ) |
| { |
| continue; |
| } |
| |
| break; |
| } |
| |
| if( cur != NULL ) |
| { |
| *dst = cur; |
| ret = 0; |
| } |
| |
| return( ret ); |
| } |
| |
| |
| int mbedtls_ssl_cache_get( void *data, |
| unsigned char const *session_id, |
| size_t session_id_len, |
| mbedtls_ssl_session *session ) |
| { |
| int ret = 1; |
| mbedtls_ssl_cache_context *cache = (mbedtls_ssl_cache_context *) data; |
| mbedtls_ssl_cache_entry *entry; |
| |
| #if defined(MBEDTLS_THREADING_C) |
| if( mbedtls_mutex_lock( &cache->mutex ) != 0 ) |
| return( 1 ); |
| #endif |
| |
| ret = ssl_cache_find_entry( cache, session_id, session_id_len, &entry ); |
| if( ret != 0 ) |
| goto exit; |
| |
| ret = mbedtls_ssl_session_load( session, |
| entry->session, |
| entry->session_len ); |
| if( ret != 0 ) |
| goto exit; |
| |
| ret = 0; |
| |
| exit: |
| #if defined(MBEDTLS_THREADING_C) |
| if( mbedtls_mutex_unlock( &cache->mutex ) != 0 ) |
| ret = 1; |
| #endif |
| |
| return( ret ); |
| } |
| |
| static int ssl_cache_pick_writing_slot( mbedtls_ssl_cache_context *cache, |
| unsigned char const *session_id, |
| size_t session_id_len, |
| mbedtls_ssl_cache_entry **dst ) |
| { |
| #if defined(MBEDTLS_HAVE_TIME) |
| mbedtls_time_t t = mbedtls_time( NULL ), oldest = 0; |
| #endif /* MBEDTLS_HAVE_TIME */ |
| |
| mbedtls_ssl_cache_entry *old = NULL; |
| int count = 0; |
| mbedtls_ssl_cache_entry *cur, *prv; |
| |
| cur = cache->chain; |
| prv = NULL; |
| |
| /* Check 1: Is there already an entry with the given session ID? |
| * |
| * If yes, overwrite it. |
| * |
| * If not, `count` will hold the size of the session cache |
| * at the end of this loop, and `prv` will point to the last |
| * entry, both of which will be used later. */ |
| |
| while( cur != NULL ) |
| { |
| count++; |
| |
| if( session_id_len == cur->session_id_len && |
| memcmp( session_id, cur->session_id, cur->session_id_len ) == 0 ) |
| { |
| goto found; |
| } |
| |
| prv = cur; |
| cur = cur->next; |
| } |
| |
| /* Check 2: Is there an outdated entry in the cache? |
| * |
| * If so, overwrite it. |
| * |
| * If not, remember the oldest entry in `old` for later. |
| */ |
| |
| #if defined(MBEDTLS_HAVE_TIME) |
| while( cur != NULL ) |
| { |
| if( cache->timeout != 0 && |
| (int) ( t - cur->timestamp ) > cache->timeout ) |
| { |
| goto found; |
| } |
| |
| if( oldest == 0 || cur->timestamp < oldest ) |
| { |
| oldest = cur->timestamp; |
| old = cur; |
| } |
| |
| prv = cur; |
| cur = cur->next; |
| } |
| #endif /* MBEDTLS_HAVE_TIME */ |
| |
| /* Check 3: Is there free space in the cache? */ |
| |
| if( count < cache->max_entries ) |
| { |
| /* Create new entry */ |
| cur = mbedtls_calloc( 1, sizeof(mbedtls_ssl_cache_entry) ); |
| if( cur == NULL ) |
| return( 1 ); |
| |
| /* Append to the end of the linked list. */ |
| if( prv == NULL ) |
| cache->chain = cur; |
| else |
| prv->next = cur; |
| |
| goto found; |
| } |
| |
| /* Last resort: The cache is full and doesn't contain any outdated |
| * elements. In this case, we evict the oldest one, judged by timestamp |
| * (if present) or cache-order. */ |
| |
| #if defined(MBEDTLS_HAVE_TIME) |
| if( old == NULL ) |
| { |
| /* This should only happen on an ill-configured cache |
| * with max_entries == 0. */ |
| return( 1 ); |
| } |
| #else /* MBEDTLS_HAVE_TIME */ |
| /* Reuse first entry in chain, but move to last place. */ |
| if( cache->chain == NULL ) |
| return( 1 ); |
| |
| old = cache->chain; |
| cache->chain = old->next; |
| cur->next = NULL; |
| prv->next = old; |
| #endif /* MBEDTLS_HAVE_TIME */ |
| |
| /* Now `old` points to the oldest entry to be overwritten. */ |
| cur = old; |
| |
| found: |
| |
| #if defined(MBEDTLS_HAVE_TIME) |
| cur->timestamp = t; |
| #endif |
| |
| /* If we're reusing an entry, free it first. */ |
| if( cur->session != NULL ) |
| { |
| mbedtls_free( cur->session ); |
| cur->session = NULL; |
| cur->session_len = 0; |
| memset( cur->session_id, 0, sizeof( cur->session_id ) ); |
| cur->session_id_len = 0; |
| } |
| |
| *dst = cur; |
| return( 0 ); |
| } |
| |
| int mbedtls_ssl_cache_set( void *data, |
| unsigned char const *session_id, |
| size_t session_id_len, |
| const mbedtls_ssl_session *session ) |
| { |
| int ret = 1; |
| mbedtls_ssl_cache_context *cache = (mbedtls_ssl_cache_context *) data; |
| mbedtls_ssl_cache_entry *cur; |
| |
| size_t session_serialized_len; |
| unsigned char *session_serialized = NULL; |
| |
| #if defined(MBEDTLS_THREADING_C) |
| if( ( ret = mbedtls_mutex_lock( &cache->mutex ) ) != 0 ) |
| return( ret ); |
| #endif |
| |
| ret = ssl_cache_pick_writing_slot( cache, |
| session_id, session_id_len, |
| &cur ); |
| if( ret != 0 ) |
| goto exit; |
| |
| /* Check how much space we need to serialize the session |
| * and allocate a sufficiently large buffer. */ |
| ret = mbedtls_ssl_session_save( session, NULL, 0, &session_serialized_len ); |
| if( ret != MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL ) |
| { |
| ret = 1; |
| goto exit; |
| } |
| |
| session_serialized = mbedtls_calloc( 1, session_serialized_len ); |
| if( session_serialized == NULL ) |
| { |
| ret = MBEDTLS_ERR_SSL_ALLOC_FAILED; |
| goto exit; |
| } |
| |
| /* Now serialize the session into the allocated buffer. */ |
| ret = mbedtls_ssl_session_save( session, |
| session_serialized, |
| session_serialized_len, |
| &session_serialized_len ); |
| if( ret != 0 ) |
| goto exit; |
| |
| if( session_id_len > sizeof( cur->session_id ) ) |
| { |
| ret = 1; |
| goto exit; |
| } |
| cur->session_id_len = session_id_len; |
| memcpy( cur->session_id, session_id, session_id_len ); |
| |
| cur->session = session_serialized; |
| cur->session_len = session_serialized_len; |
| session_serialized = NULL; |
| |
| ret = 0; |
| |
| exit: |
| #if defined(MBEDTLS_THREADING_C) |
| if( mbedtls_mutex_unlock( &cache->mutex ) != 0 ) |
| ret = 1; |
| #endif |
| |
| if( session_serialized != NULL ) |
| mbedtls_platform_zeroize( session_serialized, session_serialized_len ); |
| |
| 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_free( prv->session ); |
| mbedtls_free( prv ); |
| } |
| |
| #if defined(MBEDTLS_THREADING_C) |
| mbedtls_mutex_free( &cache->mutex ); |
| #endif |
| cache->chain = NULL; |
| } |
| |
| #endif /* MBEDTLS_SSL_CACHE_C */ |