mbedtls/library/ssl_cache.c

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/*
* SSL session cache implementation
*
* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
*
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* 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
*
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* http://www.apache.org/licenses/LICENSE-2.0
*
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* 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)
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#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;
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#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_init( &cache->mutex );
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#endif
}
int mbedtls_ssl_cache_get( void *data,
unsigned char const *session_id,
size_t session_id_len,
mbedtls_ssl_session *session )
{
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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 )
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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,
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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 )
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{
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;
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ret = 1;
goto exit;
}
}
#endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
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ret = 0;
goto exit;
}
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exit:
#if defined(MBEDTLS_THREADING_C)
if( mbedtls_mutex_unlock( &cache->mutex ) != 0 )
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ret = 1;
#endif
return( ret );
}
static int ssl_cache_find_fresh_entry( mbedtls_ssl_cache_context *cache,
unsigned char const *session_id,
size_t session_id_len,
mbedtls_ssl_cache_entry **dst )
{
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int ret = 1;
#if defined(MBEDTLS_HAVE_TIME)
mbedtls_time_t t = mbedtls_time( NULL ), oldest = 0;
mbedtls_ssl_cache_entry *old = NULL;
#endif
int count = 0;
mbedtls_ssl_cache_entry *cur, *prv;
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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( session_id_len == cur->session.id_len &&
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 )
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{
ret = 1;
goto exit;
}
cur = cache->chain;
cache->chain = cur->next;
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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 )
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{
ret = 1;
goto exit;
}
if( prv == NULL )
cache->chain = cur;
else
prv->next = cur;
}
#if defined(MBEDTLS_HAVE_TIME)
cur->timestamp = t;
#endif
}
if( cur != NULL )
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{
*dst = cur;
/*
* 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) );
}
ret = 0;
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}
exit:
return( ret );
}
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;
#if defined(MBEDTLS_THREADING_C)
if( ( ret = mbedtls_mutex_lock( &cache->mutex ) ) != 0 )
return( ret );
#endif
ret = ssl_cache_find_fresh_entry( cache,
session_id, session_id_len,
&cur );
if( ret != 0 )
goto exit;
/* 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;
}
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#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 )
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{
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 */
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ret = 0;
exit:
#if defined(MBEDTLS_THREADING_C)
if( mbedtls_mutex_unlock( &cache->mutex ) != 0 )
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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 );
}
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#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_free( &cache->mutex );
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#endif
cache->chain = NULL;
}
#endif /* MBEDTLS_SSL_CACHE_C */