From 6863619a2f94c23948a4abbf7269bc31437f99ab Mon Sep 17 00:00:00 2001 From: Hanno Becker Date: Tue, 5 Feb 2019 14:36:34 +0000 Subject: [PATCH] Introduce helper function for peer CRT chain verification --- library/ssl_tls.c | 285 ++++++++++++++++++++++++---------------------- 1 file changed, 150 insertions(+), 135 deletions(-) diff --git a/library/ssl_tls.c b/library/ssl_tls.c index 7d88582b6..01428f03a 100644 --- a/library/ssl_tls.c +++ b/library/ssl_tls.c @@ -5981,11 +5981,155 @@ static int ssl_parse_certificate_coordinate( mbedtls_ssl_context *ssl, return( SSL_CERTIFICATE_EXPECTED ); } -int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl ) +static int ssl_parse_certificate_verify( mbedtls_ssl_context *ssl, + int authmode, + mbedtls_x509_crt *chain, + void *rs_ctx ) { int ret = 0; const mbedtls_ssl_ciphersuite_t *ciphersuite_info = ssl->transform_negotiate->ciphersuite_info; + mbedtls_x509_crt *ca_chain; + mbedtls_x509_crl *ca_crl; + + if( authmode == MBEDTLS_SSL_VERIFY_NONE ) + return( 0 ); + +#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) + if( ssl->handshake->sni_ca_chain != NULL ) + { + ca_chain = ssl->handshake->sni_ca_chain; + ca_crl = ssl->handshake->sni_ca_crl; + } + else +#endif + { + ca_chain = ssl->conf->ca_chain; + ca_crl = ssl->conf->ca_crl; + } + + /* + * Main check: verify certificate + */ + ret = mbedtls_x509_crt_verify_restartable( + chain, + ca_chain, ca_crl, + ssl->conf->cert_profile, + ssl->hostname, + &ssl->session_negotiate->verify_result, + ssl->conf->f_vrfy, ssl->conf->p_vrfy, rs_ctx ); + + if( ret != 0 ) + { + MBEDTLS_SSL_DEBUG_RET( 1, "x509_verify_cert", ret ); + } + +#if defined(MBEDTLS_SSL__ECP_RESTARTABLE) + if( ret == MBEDTLS_ERR_ECP_IN_PROGRESS ) + return( MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS ); +#endif + + /* + * Secondary checks: always done, but change 'ret' only if it was 0 + */ + +#if defined(MBEDTLS_ECP_C) + { + const mbedtls_pk_context *pk = &chain->pk; + + /* If certificate uses an EC key, make sure the curve is OK */ + if( mbedtls_pk_can_do( pk, MBEDTLS_PK_ECKEY ) && + mbedtls_ssl_check_curve( ssl, mbedtls_pk_ec( *pk )->grp.id ) != 0 ) + { + ssl->session_negotiate->verify_result |= MBEDTLS_X509_BADCERT_BAD_KEY; + + MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate (EC key curve)" ) ); + if( ret == 0 ) + ret = MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE; + } + } +#endif /* MBEDTLS_ECP_C */ + + if( mbedtls_ssl_check_cert_usage( chain, + ciphersuite_info, + ! ssl->conf->endpoint, + &ssl->session_negotiate->verify_result ) != 0 ) + { + MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate (usage extensions)" ) ); + if( ret == 0 ) + ret = MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE; + } + + /* mbedtls_x509_crt_verify_with_profile is supposed to report a + * verification failure through MBEDTLS_ERR_X509_CERT_VERIFY_FAILED, + * with details encoded in the verification flags. All other kinds + * of error codes, including those from the user provided f_vrfy + * functions, are treated as fatal and lead to a failure of + * ssl_parse_certificate even if verification was optional. */ + if( authmode == MBEDTLS_SSL_VERIFY_OPTIONAL && + ( ret == MBEDTLS_ERR_X509_CERT_VERIFY_FAILED || + ret == MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE ) ) + { + ret = 0; + } + + if( ca_chain == NULL && authmode == MBEDTLS_SSL_VERIFY_REQUIRED ) + { + MBEDTLS_SSL_DEBUG_MSG( 1, ( "got no CA chain" ) ); + ret = MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED; + } + + if( ret != 0 ) + { + uint8_t alert; + + /* The certificate may have been rejected for several reasons. + Pick one and send the corresponding alert. Which alert to send + may be a subject of debate in some cases. */ + if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_OTHER ) + alert = MBEDTLS_SSL_ALERT_MSG_ACCESS_DENIED; + else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_CN_MISMATCH ) + alert = MBEDTLS_SSL_ALERT_MSG_BAD_CERT; + else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_KEY_USAGE ) + alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT; + else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_EXT_KEY_USAGE ) + alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT; + else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_NS_CERT_TYPE ) + alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT; + else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_BAD_PK ) + alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT; + else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_BAD_KEY ) + alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT; + else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_EXPIRED ) + alert = MBEDTLS_SSL_ALERT_MSG_CERT_EXPIRED; + else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_REVOKED ) + alert = MBEDTLS_SSL_ALERT_MSG_CERT_REVOKED; + else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_NOT_TRUSTED ) + alert = MBEDTLS_SSL_ALERT_MSG_UNKNOWN_CA; + else + alert = MBEDTLS_SSL_ALERT_MSG_CERT_UNKNOWN; + mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL, + alert ); + } + +#if defined(MBEDTLS_DEBUG_C) + if( ssl->session_negotiate->verify_result != 0 ) + { + MBEDTLS_SSL_DEBUG_MSG( 3, ( "! Certificate verification flags %x", + ssl->session_negotiate->verify_result ) ); + } + else + { + MBEDTLS_SSL_DEBUG_MSG( 3, ( "Certificate verification flags clear" ) ); + } +#endif /* MBEDTLS_DEBUG_C */ + + return( ret ); +} + +int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl ) +{ + int ret = 0; int crt_expected; #if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) const int authmode = ssl->handshake->sni_authmode != MBEDTLS_SSL_VERIFY_UNSET @@ -6050,140 +6194,11 @@ crt_verify: rs_ctx = &ssl->handshake->ecrs_ctx; #endif - if( authmode != MBEDTLS_SSL_VERIFY_NONE ) - { - mbedtls_x509_crt *ca_chain; - mbedtls_x509_crl *ca_crl; - -#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) - if( ssl->handshake->sni_ca_chain != NULL ) - { - ca_chain = ssl->handshake->sni_ca_chain; - ca_crl = ssl->handshake->sni_ca_crl; - } - else -#endif - { - ca_chain = ssl->conf->ca_chain; - ca_crl = ssl->conf->ca_crl; - } - - /* - * Main check: verify certificate - */ - ret = mbedtls_x509_crt_verify_restartable( - ssl->session_negotiate->peer_cert, - ca_chain, ca_crl, - ssl->conf->cert_profile, - ssl->hostname, - &ssl->session_negotiate->verify_result, - ssl->conf->f_vrfy, ssl->conf->p_vrfy, rs_ctx ); - - if( ret != 0 ) - { - MBEDTLS_SSL_DEBUG_RET( 1, "x509_verify_cert", ret ); - } - -#if defined(MBEDTLS_SSL__ECP_RESTARTABLE) - if( ret == MBEDTLS_ERR_ECP_IN_PROGRESS ) - return( MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS ); -#endif - - /* - * Secondary checks: always done, but change 'ret' only if it was 0 - */ - -#if defined(MBEDTLS_ECP_C) - { - const mbedtls_pk_context *pk = &ssl->session_negotiate->peer_cert->pk; - - /* If certificate uses an EC key, make sure the curve is OK */ - if( mbedtls_pk_can_do( pk, MBEDTLS_PK_ECKEY ) && - mbedtls_ssl_check_curve( ssl, mbedtls_pk_ec( *pk )->grp.id ) != 0 ) - { - ssl->session_negotiate->verify_result |= MBEDTLS_X509_BADCERT_BAD_KEY; - - MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate (EC key curve)" ) ); - if( ret == 0 ) - ret = MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE; - } - } -#endif /* MBEDTLS_ECP_C */ - - if( mbedtls_ssl_check_cert_usage( ssl->session_negotiate->peer_cert, - ciphersuite_info, - ! ssl->conf->endpoint, - &ssl->session_negotiate->verify_result ) != 0 ) - { - MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad certificate (usage extensions)" ) ); - if( ret == 0 ) - ret = MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE; - } - - /* mbedtls_x509_crt_verify_with_profile is supposed to report a - * verification failure through MBEDTLS_ERR_X509_CERT_VERIFY_FAILED, - * with details encoded in the verification flags. All other kinds - * of error codes, including those from the user provided f_vrfy - * functions, are treated as fatal and lead to a failure of - * ssl_parse_certificate even if verification was optional. */ - if( authmode == MBEDTLS_SSL_VERIFY_OPTIONAL && - ( ret == MBEDTLS_ERR_X509_CERT_VERIFY_FAILED || - ret == MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE ) ) - { - ret = 0; - } - - if( ca_chain == NULL && authmode == MBEDTLS_SSL_VERIFY_REQUIRED ) - { - MBEDTLS_SSL_DEBUG_MSG( 1, ( "got no CA chain" ) ); - ret = MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED; - } - - if( ret != 0 ) - { - uint8_t alert; - - /* The certificate may have been rejected for several reasons. - Pick one and send the corresponding alert. Which alert to send - may be a subject of debate in some cases. */ - if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_OTHER ) - alert = MBEDTLS_SSL_ALERT_MSG_ACCESS_DENIED; - else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_CN_MISMATCH ) - alert = MBEDTLS_SSL_ALERT_MSG_BAD_CERT; - else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_KEY_USAGE ) - alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT; - else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_EXT_KEY_USAGE ) - alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT; - else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_NS_CERT_TYPE ) - alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT; - else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_BAD_PK ) - alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT; - else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_BAD_KEY ) - alert = MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT; - else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_EXPIRED ) - alert = MBEDTLS_SSL_ALERT_MSG_CERT_EXPIRED; - else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_REVOKED ) - alert = MBEDTLS_SSL_ALERT_MSG_CERT_REVOKED; - else if( ssl->session_negotiate->verify_result & MBEDTLS_X509_BADCERT_NOT_TRUSTED ) - alert = MBEDTLS_SSL_ALERT_MSG_UNKNOWN_CA; - else - alert = MBEDTLS_SSL_ALERT_MSG_CERT_UNKNOWN; - mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL, - alert ); - } - -#if defined(MBEDTLS_DEBUG_C) - if( ssl->session_negotiate->verify_result != 0 ) - { - MBEDTLS_SSL_DEBUG_MSG( 3, ( "! Certificate verification flags %x", - ssl->session_negotiate->verify_result ) ); - } - else - { - MBEDTLS_SSL_DEBUG_MSG( 3, ( "Certificate verification flags clear" ) ); - } -#endif /* MBEDTLS_DEBUG_C */ - } + ret = ssl_parse_certificate_verify( ssl, authmode, + ssl->session_negotiate->peer_cert, + rs_ctx ); + if( ret != 0 ) + return( ret ); MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse certificate" ) );