diff --git a/library/ssl_tls.c b/library/ssl_tls.c index 5a72fede49..cf9583ccb7 100644 --- a/library/ssl_tls.c +++ b/library/ssl_tls.c @@ -1710,7 +1710,8 @@ int mbedtls_ssl_set_hs_psk( mbedtls_ssl_context *ssl, else alg = PSA_ALG_TLS12_PSK_TO_MS(PSA_ALG_SHA_256); - psa_set_key_usage_flags( &key_attributes, PSA_KEY_USAGE_DERIVE ); + psa_set_key_usage_flags( &key_attributes, + PSA_KEY_USAGE_DERIVE | PSA_KEY_USAGE_EXPORT ); psa_set_key_algorithm( &key_attributes, alg ); psa_set_key_type( &key_attributes, PSA_KEY_TYPE_DERIVE ); diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c index 02a2850edf..104d5b62b9 100644 --- a/library/ssl_tls13_server.c +++ b/library/ssl_tls13_server.c @@ -24,6 +24,7 @@ #include "mbedtls/debug.h" #include "mbedtls/error.h" #include "mbedtls/platform.h" +#include "mbedtls/constant_time.h" #include "ssl_misc.h" #include "ssl_tls13_keys.h" @@ -97,6 +98,269 @@ static int ssl_tls13_parse_key_exchange_modes_ext( mbedtls_ssl_context *ssl, ssl->handshake->tls13_kex_modes = ke_modes; return( 0 ); } + +#define SSL_TLS1_3_OFFERED_PSK_NOT_MATCH 0 +#define SSL_TLS1_3_OFFERED_PSK_MATCH 1 +static int ssl_tls13_offered_psks_check_identity_match( + mbedtls_ssl_context *ssl, + const unsigned char *identity, + uint16_t identity_len ) +{ + /* Check identity with external configured function */ + if( ssl->conf->f_psk != NULL ) + { + if( ssl->conf->f_psk( + ssl->conf->p_psk, ssl, identity, identity_len ) == 0 ) + { + return( SSL_TLS1_3_OFFERED_PSK_MATCH ); + } + return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH ); + } + + /* Check identity with pre-configured psk */ + if( identity_len == ssl->conf->psk_identity_len && + mbedtls_ct_memcmp( ssl->conf->psk_identity, + identity, identity_len ) == 0 ) + { + mbedtls_ssl_set_hs_psk( ssl, ssl->conf->psk, ssl->conf->psk_len ); + return( SSL_TLS1_3_OFFERED_PSK_MATCH ); + } + + /* Add session ticket here */ + + return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH ); +} + +static int ssl_tls13_offered_psks_check_binder_match( + mbedtls_ssl_context *ssl, + const unsigned char *binder, + uint16_t binder_len, + const unsigned char *psk, + size_t psk_len ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + int psk_type; + mbedtls_md_type_t md_alg = + binder_len == 32 ? MBEDTLS_MD_SHA256 : MBEDTLS_MD_SHA384 ; + psa_algorithm_t psa_md_alg = mbedtls_psa_translate_md( md_alg ); + unsigned char transcript[MBEDTLS_MD_MAX_SIZE]; + size_t transcript_len; + unsigned char server_computed_binder[MBEDTLS_MD_MAX_SIZE]; + + if( ssl->handshake->resume == 1 ) + psk_type = MBEDTLS_SSL_TLS1_3_PSK_RESUMPTION; + else + psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL; + + /* Get current state of handshake transcript. */ + ret = mbedtls_ssl_get_handshake_transcript( ssl, md_alg, + transcript, sizeof( transcript ), + &transcript_len ); + if( ret != 0 ) + return( ret ); + + ret = mbedtls_ssl_tls13_create_psk_binder( ssl, psa_md_alg, + psk, psk_len, psk_type, + transcript, + server_computed_binder ); + /* We do not check for multiple binders */ + if( ret != 0 ) + { + MBEDTLS_SSL_DEBUG_MSG( 1, ( "PSK binder calculation failed." ) ); + return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); + } + + MBEDTLS_SSL_DEBUG_BUF( 3, "psk binder ( computed ): ", + server_computed_binder, binder_len ); + MBEDTLS_SSL_DEBUG_BUF( 3, "psk binder ( received ): ", binder, binder_len ); + + if( mbedtls_ct_memcmp( server_computed_binder, binder, binder_len ) == 0 ) + { + return( SSL_TLS1_3_OFFERED_PSK_MATCH ); + } + + return( SSL_TLS1_3_OFFERED_PSK_NOT_MATCH ); +} +/* Parser for pre_shared_key extension in client hello + * struct { + * opaque identity<1..2^16-1>; + * uint32 obfuscated_ticket_age; + * } PskIdentity; + * + * opaque PskBinderEntry<32..255>; + * + * struct { + * PskIdentity identities<7..2^16-1>; + * PskBinderEntry binders<33..2^16-1>; + * } OfferedPsks; + * + * struct { + * select (Handshake.msg_type) { + * case client_hello: OfferedPsks; + * .... + * }; + * } PreSharedKeyExtension; + */ +static int ssl_tls13_parse_offered_psks_ext( mbedtls_ssl_context *ssl, + const unsigned char *buf, + const unsigned char *end ) +{ + int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; + const unsigned char *p = buf; + uint16_t identities_len; + const unsigned char *identities_end; + uint32_t identity_matched = SSL_TLS1_3_OFFERED_PSK_NOT_MATCH; + uint16_t binders_len; + const unsigned char *binders_end; + unsigned char *psk = NULL; + size_t psk_len = 0; + int binder_matched = 0; +#if defined(MBEDTLS_USE_PSA_CRYPTO) + psa_key_attributes_t key_attributes = PSA_KEY_ATTRIBUTES_INIT; + psa_status_t status; +#endif /* MBEDTLS_USE_PSA_CRYPTO */ + + MBEDTLS_SSL_DEBUG_BUF( 3, "pre_shared_key extesion", buf, end - buf ); + + /* identities >= 7 bytes */ + MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 7 ); + + identities_len = MBEDTLS_GET_UINT16_BE( p, 0 ); + p += 2; + MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, identities_len ); + identities_end = p + identities_len; + + while( p < identities_end ) + { + uint16_t identity_len; + const unsigned char *identity; + MBEDTLS_SSL_CHK_BUF_READ_PTR( p, identities_end, 2 ); + identity_len = MBEDTLS_GET_UINT16_BE( p, 0 ); + p += 2; + identity = p; + p += identity_len; + p += 4; // skip obfuscated_ticket_age + MBEDTLS_SSL_CHK_BUF_READ_PTR( identity, identities_end, identity_len ); + + if( identity_matched == SSL_TLS1_3_OFFERED_PSK_MATCH ) + continue; + + MBEDTLS_SSL_DEBUG_BUF( 3, "received psk identity", + identity, identity_len ); + identity_matched = ssl_tls13_offered_psks_check_identity_match( + ssl, identity, identity_len ); + } + + if( identity_matched != SSL_TLS1_3_OFFERED_PSK_MATCH ) + { + MBEDTLS_SSL_PEND_FATAL_ALERT( + MBEDTLS_SSL_ALERT_LEVEL_FATAL, + MBEDTLS_SSL_ALERT_MSG_UNKNOWN_PSK_IDENTITY ); + return( MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY ); + } + + if( p != identities_end ) + { + MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key extesion decode error" ) ); + MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, + MBEDTLS_ERR_SSL_DECODE_ERROR ); + return( MBEDTLS_ERR_SSL_DECODE_ERROR ); + } + + ssl->handshake->update_checksum( ssl, buf, p - buf ); + + /* binders >= 33 bytes */ + MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 33 ); + binders_len = MBEDTLS_GET_UINT16_BE( p, 0 ); + p += 2; + MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, binders_len ); + binders_end = p + binders_len; + +#if defined(MBEDTLS_USE_PSA_CRYPTO) + status = psa_get_key_attributes( ssl->handshake->psk_opaque, + &key_attributes ); + if( status != PSA_SUCCESS) + { + return( psa_ssl_status_to_mbedtls( status ) ); + } + + psk_len = PSA_BITS_TO_BYTES(psa_get_key_bits( &key_attributes ) ); + psk = mbedtls_calloc( 1, psk_len ); + if( psk == NULL ) + { + return( MBEDTLS_ERR_SSL_ALLOC_FAILED ); + } + status = psa_export_key(ssl->handshake->psk_opaque, psk, psk_len, &psk_len ); + if( status != PSA_SUCCESS) + { + ret = psa_ssl_status_to_mbedtls( status ); + goto exit_failue; + } +#else + psk = ssl->handshake->psk; + psk_len = ssl->handshake->psk_len; +#endif /* !MBEDTLS_USE_PSA_CRYPTO */ + + while( p < binders_end ) + { + uint8_t binder_len; + const unsigned char *binder; + + MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 1 ); + binder_len = *p++; + MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, binder_len ); + binder = p; + p += binder_len; + + if( binder_matched == SSL_TLS1_3_OFFERED_PSK_MATCH) + continue; + + binder_matched = ssl_tls13_offered_psks_check_binder_match( + ssl, binder, binder_len, psk, psk_len ); + if( binder_matched < 0 ) + { + MBEDTLS_SSL_DEBUG_RET( 1, + "ssl_tls13_offered_psks_check_binder_match" , binder_matched ); + MBEDTLS_SSL_PEND_FATAL_ALERT( + MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, + MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); + ret = binder_matched; + goto exit_failue; + } + } + + if( binder_matched != SSL_TLS1_3_OFFERED_PSK_MATCH ) + { + MBEDTLS_SSL_DEBUG_MSG( 1, + ( "Received psk binder does not match computed psk binder." ) ); + MBEDTLS_SSL_PEND_FATAL_ALERT( + MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE, + MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); + ret = MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE; + goto exit_failue; + } + + if( p != binders_end ) + { + MBEDTLS_SSL_DEBUG_MSG( 3, ( "pre_shared_key extesion decode error" ) ); + MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECODE_ERROR, + MBEDTLS_ERR_SSL_DECODE_ERROR ); + ret = MBEDTLS_ERR_SSL_DECODE_ERROR; + goto exit_failue; + } + + /* Update the handshake transcript with the binder list. */ + ssl->handshake->update_checksum( ssl, + identities_end, + (size_t)( p - identities_end ) ); + ret = 0; + +exit_failue: +#if defined(MBEDTLS_USE_PSA_CRYPTO) + mbedtls_free( (void *)psk ); +#endif + return( ret ); +} #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */ /* From RFC 8446: @@ -540,6 +804,10 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl, int hrr_required = 0; const mbedtls_ssl_ciphersuite_t* ciphersuite_info; +#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED) + const unsigned char *pre_shared_key_ext_start = NULL; + const unsigned char *pre_shared_key_ext_end = NULL; +#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */ ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE; @@ -825,6 +1093,20 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl, break; #endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */ +#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED) + case MBEDTLS_TLS_EXT_PRE_SHARED_KEY: + MBEDTLS_SSL_DEBUG_MSG( 3, ( "found pre_shared_key extension" ) ); + /* Delay processing of the PSK identity once we have + * found out which algorithms to use. We keep a pointer + * to the buffer and the size for later processing. + */ + pre_shared_key_ext_start = p; + pre_shared_key_ext_end = extension_data_end; + + ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PRE_SHARED_KEY; + break; +#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */ + #if defined(MBEDTLS_SSL_ALPN) case MBEDTLS_TLS_EXT_ALPN: MBEDTLS_SSL_DEBUG_MSG( 3, ( "found alpn extension" ) ); @@ -866,17 +1148,48 @@ static int ssl_tls13_parse_client_hello( mbedtls_ssl_context *ssl, p += extension_data_len; } + +#if defined(MBEDTLS_DEBUG_C) + /* List all the extensions we have received */ + ssl_tls13_debug_print_client_hello_exts( ssl ); +#endif /* MBEDTLS_DEBUG_C */ + + mbedtls_ssl_add_hs_hdr_to_checksum( ssl, + MBEDTLS_SSL_HS_CLIENT_HELLO, + p - buf ); +#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED) /* Update checksum with either * - The entire content of the CH message, if no PSK extension is present * - The content up to but excluding the PSK extension, if present. */ - mbedtls_ssl_add_hs_msg_to_checksum( ssl, MBEDTLS_SSL_HS_CLIENT_HELLO, - buf, p - buf ); - - /* List all the extensions we have received */ -#if defined(MBEDTLS_DEBUG_C) - ssl_tls13_debug_print_client_hello_exts( ssl ); -#endif /* MBEDTLS_DEBUG_C */ + /* If we've settled on a PSK-based exchange, parse PSK identity ext */ + if( mbedtls_ssl_conf_tls13_some_psk_enabled( ssl ) && + ( ssl->handshake->extensions_present & MBEDTLS_SSL_EXT_PRE_SHARED_KEY ) ) + { + ssl->handshake->update_checksum( ssl, buf, + pre_shared_key_ext_start - buf ); + ret = ssl_tls13_parse_offered_psks_ext( ssl, + pre_shared_key_ext_start, + pre_shared_key_ext_end ); + if( ret != 0 ) + { + MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_tls13_parse_offered_psks_ext" ), + ret ); + return( ret ); + } + /* If pre_shared_key is not last extension */ + if( p - pre_shared_key_ext_end ) + { + ssl->handshake->update_checksum( ssl, + pre_shared_key_ext_end, + p - pre_shared_key_ext_end ); + } + } + else +#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */ + { + ssl->handshake->update_checksum( ssl, buf, p - buf ); + } return( hrr_required ? SSL_CLIENT_HELLO_HRR_REQUIRED : SSL_CLIENT_HELLO_OK ); }