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Parse and verify peer CRT chain in local variable

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`mbedtls_ssl_parse_certificate()` parses the peer's certificate chain
directly into the `peer_cert` field of the `mbedtls_ssl_session`
structure being established. To allow to optionally remove this field
from the session structure, this commit changes this to parse the peer's
chain into a local variable instead first, which can then either be freed
after CRT verification - in case the chain should not be stored - or
mapped to the `peer_cert` if it should be kept. For now, only the latter
is implemented.
This commit is contained in:
Hanno Becker 2019-02-05 17:19:52 +00:00
parent 177475a3aa
commit 3dad311ef0
2 changed files with 51 additions and 18 deletions
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3
include/mbedtls/ssl_internal.h
View file

@ -331,6 +331,9 @@ struct mbedtls_ssl_handshake_params
ssl_ecrs_cke_ecdh_calc_secret, /*!< ClientKeyExchange: ECDH step 2 */
ssl_ecrs_crt_vrfy_sign, /*!< CertificateVerify: pk_sign() */
} ecrs_state; /*!< current (or last) operation */
#if defined(MBEDTLS_X509_CRT_PARSE_C)
mbedtls_x509_crt *ecrs_peer_cert; /*!< The peer's CRT chain. */
#endif /* MBEDTLS_X509_CRT_PARSE_C */
size_t ecrs_n; /*!< place for saving a length */
#endif
#if defined(MBEDTLS_SSL_PROTO_DTLS)

66
library/ssl_tls.c
View file

@ -6176,6 +6176,7 @@ int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl )
const int authmode = ssl->conf->authmode;
#endif
void *rs_ctx = NULL;
mbedtls_x509_crt *chain = NULL;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate" ) );
@ -6190,6 +6191,8 @@ int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl )
if( ssl->handshake->ecrs_enabled &&
ssl->handshake->ecrs_state == ssl_ecrs_crt_verify )
{
chain = ssl->handshake->ecrs_peer_cert;
ssl->handshake->ecrs_peer_cert = NULL;
goto crt_verify;
}
#endif
@ -6199,7 +6202,7 @@ int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl )
/* mbedtls_ssl_read_record may have sent an alert already. We
let it decide whether to alert. */
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
return( ret );
goto exit;
}
#if defined(MBEDTLS_SSL_SRV_C)
@ -6219,22 +6222,24 @@ int mbedtls_ssl_parse_certificate( mbedtls_ssl_context *ssl )
/* Clear existing peer CRT structure in case we tried to
* reuse a session but it failed, and allocate a new one. */
ssl_clear_peer_cert( ssl->session_negotiate );
ssl->session_negotiate->peer_cert =
mbedtls_calloc( 1, sizeof( mbedtls_x509_crt ) );
if( ssl->session_negotiate->peer_cert == NULL )
chain = mbedtls_calloc( 1, sizeof( mbedtls_x509_crt ) );
if( chain == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc(%d bytes) failed",
sizeof( mbedtls_x509_crt ) ) );
mbedtls_ssl_send_alert_message( ssl,
MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
}
mbedtls_x509_crt_init( ssl->session_negotiate->peer_cert );
ret = ssl_parse_certificate_chain( ssl, ssl->session_negotiate->peer_cert );
ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
goto exit;
}
mbedtls_x509_crt_init( chain );
ret = ssl_parse_certificate_chain( ssl, chain );
if( ret != 0 )
return( ret );
goto exit;
#if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
if( ssl->handshake->ecrs_enabled)
@ -6246,12 +6251,12 @@ crt_verify:
#endif
ret = ssl_parse_certificate_verify( ssl, authmode,
ssl->session_negotiate->peer_cert,
rs_ctx );
chain, rs_ctx );
if( ret != 0 )
return( ret );
goto exit;
#if !defined(MBEDTLS_SSL_KEEP_PEER_CERTIFICATE)
/* Remember digest of the peer's end-CRT. */
ssl->session_negotiate->peer_cert_digest =
mbedtls_calloc( 1, MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_LEN );
@ -6262,15 +6267,16 @@ crt_verify:
mbedtls_ssl_send_alert_message( ssl,
MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR );
return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
goto exit;
}
ret = mbedtls_md( mbedtls_md_info_from_type(
MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_TYPE ),
ssl->session_negotiate->peer_cert->raw.p,
ssl->session_negotiate->peer_cert->raw.len,
MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_TYPE ),
chain->raw.p, chain->raw.len,
ssl->session_negotiate->peer_cert_digest );
if( ret != 0 )
return( ret );
goto exit;
ssl->session_negotiate->peer_cert_digest_type =
MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_TYPE;
@ -6278,11 +6284,30 @@ crt_verify:
MBEDTLS_SSL_PEER_CERT_DIGEST_DFL_LEN;
#endif /* !MBEDTLS_SSL_KEEP_PEER_CERTIFICATE */
ssl->session_negotiate->peer_cert = chain;
chain = NULL;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse certificate" ) );
exit:
ssl->state++;
if( ret == 0 )
ssl->state++;
#if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
if( ret == MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS )
{
ssl->handshake->ecrs_peer_cert = chain;
chain = NULL;
}
#endif
if( chain != NULL )
{
mbedtls_x509_crt_free( chain );
mbedtls_free( chain );
}
return( ret );
}
#endif /* MBEDTLS_KEY_EXCHANGE__WITH_CERT__ENABLED */
@ -9487,6 +9512,11 @@ void mbedtls_ssl_handshake_free( mbedtls_ssl_context *ssl )
#if defined(MBEDTLS_SSL__ECP_RESTARTABLE)
mbedtls_x509_crt_restart_free( &handshake->ecrs_ctx );
if( handshake->ecrs_peer_cert != NULL )
{
mbedtls_x509_crt_free( handshake->ecrs_peer_cert );
mbedtls_free( handshake->ecrs_peer_cert );
}
#endif
#if defined(MBEDTLS_SSL_PROTO_DTLS)