mbedtls ported to mbed-classic
Fork of mbedtls by
source/ssl_ticket.c
- Committer:
- Brian Daniels
- Date:
- 2016-04-07
- Revision:
- 4:bef26f687287
- Parent:
- 1:24750b9ad5ef
File content as of revision 4:bef26f687287:
/* * TLS server tickets callbacks implementation * * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved * 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. * * This file is part of mbed TLS (https://tls.mbed.org) */ #if !defined(MBEDTLS_CONFIG_FILE) #include "mbedtls/config.h" #else #include MBEDTLS_CONFIG_FILE #endif #if defined(MBEDTLS_SSL_TICKET_C) #include "mbedtls/ssl_ticket.h" #if defined(MBEDTLS_PLATFORM_C) #include "mbedtls/platform.h" #else #include <stdlib.h> #define mbedtls_calloc calloc #define mbedtls_free free #endif #include <string.h> /* Implementation that should never be optimized out by the compiler */ static void mbedtls_zeroize( void *v, size_t n ) { volatile unsigned char *p = v; while( n-- ) *p++ = 0; } /* * Initialze context */ void mbedtls_ssl_ticket_init( mbedtls_ssl_ticket_context *ctx ) { memset( ctx, 0, sizeof( mbedtls_ssl_ticket_context ) ); #if defined(MBEDTLS_THREADING_C) mbedtls_mutex_init( &ctx->mutex ); #endif } #define MAX_KEY_BYTES 32 /* 256 bits */ /* * Generate/update a key */ static int ssl_ticket_gen_key( mbedtls_ssl_ticket_context *ctx, unsigned char index ) { int ret; unsigned char buf[MAX_KEY_BYTES]; mbedtls_ssl_ticket_key *key = ctx->keys + index; #if defined(MBEDTLS_HAVE_TIME) key->generation_time = (uint32_t) time( NULL ); #endif if( ( ret = ctx->f_rng( ctx->p_rng, key->name, sizeof( key->name ) ) ) != 0 ) return( ret ); if( ( ret = ctx->f_rng( ctx->p_rng, buf, sizeof( buf ) ) ) != 0 ) return( ret ); /* With GCM and CCM, same context can encrypt & decrypt */ ret = mbedtls_cipher_setkey( &key->ctx, buf, mbedtls_cipher_get_key_bitlen( &key->ctx ), MBEDTLS_ENCRYPT ); mbedtls_zeroize( buf, sizeof( buf ) ); return( ret ); } /* * Rotate/generate keys if necessary */ static int ssl_ticket_update_keys( mbedtls_ssl_ticket_context *ctx ) { #if !defined(MBEDTLS_HAVE_TIME) ((void) ctx); #else if( ctx->ticket_lifetime != 0 ) { uint32_t current_time = (uint32_t) time( NULL ); uint32_t key_time = ctx->keys[ctx->active].generation_time; if( current_time > key_time && current_time - key_time < ctx->ticket_lifetime ) { return( 0 ); } ctx->active = 1 - ctx->active; return( ssl_ticket_gen_key( ctx, ctx->active ) ); } else #endif /* MBEDTLS_HAVE_TIME */ return( 0 ); } /* * Setup context for actual use */ int mbedtls_ssl_ticket_setup( mbedtls_ssl_ticket_context *ctx, int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, mbedtls_cipher_type_t cipher, uint32_t lifetime ) { int ret; const mbedtls_cipher_info_t *cipher_info; ctx->f_rng = f_rng; ctx->p_rng = p_rng; ctx->ticket_lifetime = lifetime; cipher_info = mbedtls_cipher_info_from_type( cipher); if( cipher_info == NULL ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); if( cipher_info->mode != MBEDTLS_MODE_GCM && cipher_info->mode != MBEDTLS_MODE_CCM ) { return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); } if( cipher_info->key_bitlen > 8 * MAX_KEY_BYTES ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); if( ( ret = mbedtls_cipher_setup( &ctx->keys[0].ctx, cipher_info ) ) != 0 || ( ret = mbedtls_cipher_setup( &ctx->keys[1].ctx, cipher_info ) ) != 0 ) { return( ret ); } if( ( ret = ssl_ticket_gen_key( ctx, 0 ) ) != 0 || ( ret = ssl_ticket_gen_key( ctx, 1 ) ) != 0 ) { return( ret ); } return( 0 ); } /* * Serialize a session in the following format: * 0 . n-1 session structure, n = sizeof(mbedtls_ssl_session) * n . n+2 peer_cert length = m (0 if no certificate) * n+3 . n+2+m peer cert ASN.1 */ static int ssl_save_session( const mbedtls_ssl_session *session, unsigned char *buf, size_t buf_len, size_t *olen ) { unsigned char *p = buf; size_t left = buf_len; #if defined(MBEDTLS_X509_CRT_PARSE_C) size_t cert_len; #endif /* MBEDTLS_X509_CRT_PARSE_C */ if( left < sizeof( mbedtls_ssl_session ) ) return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL ); memcpy( p, session, sizeof( mbedtls_ssl_session ) ); p += sizeof( mbedtls_ssl_session ); left -= sizeof( mbedtls_ssl_session ); #if defined(MBEDTLS_X509_CRT_PARSE_C) if( session->peer_cert == NULL ) cert_len = 0; else cert_len = session->peer_cert->raw.len; if( left < 3 + cert_len ) return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL ); *p++ = (unsigned char)( cert_len >> 16 & 0xFF ); *p++ = (unsigned char)( cert_len >> 8 & 0xFF ); *p++ = (unsigned char)( cert_len & 0xFF ); if( session->peer_cert != NULL ) memcpy( p, session->peer_cert->raw.p, cert_len ); p += cert_len; #endif /* MBEDTLS_X509_CRT_PARSE_C */ *olen = p - buf; return( 0 ); } /* * Unserialise session, see ssl_save_session() */ static int ssl_load_session( mbedtls_ssl_session *session, const unsigned char *buf, size_t len ) { const unsigned char *p = buf; const unsigned char * const end = buf + len; #if defined(MBEDTLS_X509_CRT_PARSE_C) size_t cert_len; #endif /* MBEDTLS_X509_CRT_PARSE_C */ if( p + sizeof( mbedtls_ssl_session ) > end ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); memcpy( session, p, sizeof( mbedtls_ssl_session ) ); p += sizeof( mbedtls_ssl_session ); #if defined(MBEDTLS_X509_CRT_PARSE_C) if( p + 3 > end ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); cert_len = ( p[0] << 16 ) | ( p[1] << 8 ) | p[2]; p += 3; if( cert_len == 0 ) { session->peer_cert = NULL; } else { int ret; if( p + cert_len > end ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); session->peer_cert = mbedtls_calloc( 1, sizeof( mbedtls_x509_crt ) ); if( session->peer_cert == NULL ) return( MBEDTLS_ERR_SSL_ALLOC_FAILED ); mbedtls_x509_crt_init( session->peer_cert ); if( ( ret = mbedtls_x509_crt_parse_der( session->peer_cert, p, cert_len ) ) != 0 ) { mbedtls_x509_crt_free( session->peer_cert ); mbedtls_free( session->peer_cert ); session->peer_cert = NULL; return( ret ); } p += cert_len; } #endif /* MBEDTLS_X509_CRT_PARSE_C */ if( p != end ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); return( 0 ); } /* * Create session ticket, with the following structure: * * struct { * opaque key_name[4]; * opaque iv[12]; * opaque encrypted_state<0..2^16-1>; * opaque tag[16]; * } ticket; * * The key_name, iv, and length of encrypted_state are the additional * authenticated data. */ int mbedtls_ssl_ticket_write( void *p_ticket, const mbedtls_ssl_session *session, unsigned char *start, const unsigned char *end, size_t *tlen, uint32_t *ticket_lifetime ) { int ret; mbedtls_ssl_ticket_context *ctx = p_ticket; mbedtls_ssl_ticket_key *key; unsigned char *key_name = start; unsigned char *iv = start + 4; unsigned char *state_len_bytes = iv + 12; unsigned char *state = state_len_bytes + 2; unsigned char *tag; size_t clear_len, ciph_len; *tlen = 0; if( ctx == NULL || ctx->f_rng == NULL ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); /* We need at least 4 bytes for key_name, 12 for IV, 2 for len 16 for tag, * in addition to session itself, that will be checked when writing it. */ if( end - start < 4 + 12 + 2 + 16 ) return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL ); #if defined(MBEDTLS_THREADING_C) if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) return( ret ); #endif if( ( ret = ssl_ticket_update_keys( ctx ) ) != 0 ) goto cleanup; key = &ctx->keys[ctx->active]; *ticket_lifetime = ctx->ticket_lifetime; memcpy( key_name, key->name, 4 ); if( ( ret = ctx->f_rng( ctx->p_rng, iv, 12 ) ) != 0 ) goto cleanup; /* Dump session state */ if( ( ret = ssl_save_session( session, state, end - state, &clear_len ) ) != 0 || (unsigned long) clear_len > 65535 ) { goto cleanup; } state_len_bytes[0] = ( clear_len >> 8 ) & 0xff; state_len_bytes[1] = ( clear_len ) & 0xff; /* Encrypt and authenticate */ tag = state + clear_len; if( ( ret = mbedtls_cipher_auth_encrypt( &key->ctx, iv, 12, key_name, 4 + 12 + 2, state, clear_len, state, &ciph_len, tag, 16 ) ) != 0 ) { goto cleanup; } if( ciph_len != clear_len ) { ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; goto cleanup; } *tlen = 4 + 12 + 2 + 16 + ciph_len; cleanup: #if defined(MBEDTLS_THREADING_C) if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); #endif return( ret ); } /* * Select key based on name */ static mbedtls_ssl_ticket_key *ssl_ticket_select_key( mbedtls_ssl_ticket_context *ctx, const unsigned char name[4] ) { unsigned char i; for( i = 0; i < sizeof( ctx->keys ) / sizeof( *ctx->keys ); i++ ) if( memcmp( name, ctx->keys[i].name, 4 ) == 0 ) return( &ctx->keys[i] ); return( NULL ); } /* * Load session ticket (see mbedtls_ssl_ticket_write for structure) */ int mbedtls_ssl_ticket_parse( void *p_ticket, mbedtls_ssl_session *session, unsigned char *buf, size_t len ) { int ret; mbedtls_ssl_ticket_context *ctx = p_ticket; mbedtls_ssl_ticket_key *key; unsigned char *key_name = buf; unsigned char *iv = buf + 4; unsigned char *enc_len_p = iv + 12; unsigned char *ticket = enc_len_p + 2; unsigned char *tag; size_t enc_len, clear_len; if( ctx == NULL || ctx->f_rng == NULL ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); /* See mbedtls_ssl_ticket_write() */ if( len < 4 + 12 + 2 + 16 ) return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA ); #if defined(MBEDTLS_THREADING_C) if( ( ret = mbedtls_mutex_lock( &ctx->mutex ) ) != 0 ) return( ret ); #endif if( ( ret = ssl_ticket_update_keys( ctx ) ) != 0 ) goto cleanup; enc_len = ( enc_len_p[0] << 8 ) | enc_len_p[1]; tag = ticket + enc_len; if( len != 4 + 12 + 2 + enc_len + 16 ) { ret = MBEDTLS_ERR_SSL_BAD_INPUT_DATA; goto cleanup; } /* Select key */ if( ( key = ssl_ticket_select_key( ctx, key_name ) ) == NULL ) { /* We can't know for sure but this is a likely option unless we're * under attack - this is only informative anyway */ ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED; goto cleanup; } /* Decrypt and authenticate */ if( ( ret = mbedtls_cipher_auth_decrypt( &key->ctx, iv, 12, key_name, 4 + 12 + 2, ticket, enc_len, ticket, &clear_len, tag, 16 ) ) != 0 ) { if( ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED ) ret = MBEDTLS_ERR_SSL_INVALID_MAC; goto cleanup; } if( clear_len != enc_len ) { ret = MBEDTLS_ERR_SSL_INTERNAL_ERROR; goto cleanup; } /* Actually load session */ if( ( ret = ssl_load_session( session, ticket, clear_len ) ) != 0 ) goto cleanup; #if defined(MBEDTLS_HAVE_TIME) { /* Check for expiration */ time_t current_time = time( NULL ); if( current_time < session->start || (uint32_t)( current_time - session->start ) > ctx->ticket_lifetime ) { ret = MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED; goto cleanup; } } #endif cleanup: #if defined(MBEDTLS_THREADING_C) if( mbedtls_mutex_unlock( &ctx->mutex ) != 0 ) return( MBEDTLS_ERR_THREADING_MUTEX_ERROR ); #endif return( ret ); } /* * Free context */ void mbedtls_ssl_ticket_free( mbedtls_ssl_ticket_context *ctx ) { mbedtls_cipher_free( &ctx->keys[0].ctx ); mbedtls_cipher_free( &ctx->keys[1].ctx ); #if defined(MBEDTLS_THREADING_C) mbedtls_mutex_free( &ctx->mutex ); #endif mbedtls_zeroize( ctx, sizeof( mbedtls_ssl_ticket_context ) ); } #endif /* MBEDTLS_SSL_TICKET_C */