Implement write_partial with dummy exts
Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
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7984d9931e
commit
bc20bdd3a9
3 changed files with 327 additions and 3 deletions
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@ -1385,6 +1385,9 @@ void mbedtls_ssl_add_hs_hdr_to_checksum( mbedtls_ssl_context *ssl,
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unsigned hs_type,
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size_t total_hs_len );
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#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
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int mbedtls_ssl_write_signature_algorithms_ext(mbedtls_ssl_context* ssl, unsigned char* buf, unsigned char* end, size_t* olen);
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#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
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#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
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@ -25,6 +25,8 @@
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#if defined(MBEDTLS_SSL_CLI_C)
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#include <string.h>
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#include "ssl_misc.h"
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#include <mbedtls/debug.h>
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@ -137,20 +139,305 @@ static int ssl_client_hello_postprocess( mbedtls_ssl_context* ssl )
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return( 0 );
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}
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/* Write extensions */
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static void ssl_write_supported_versions_ext( mbedtls_ssl_context *ssl,
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unsigned char* buf,
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unsigned char* end,
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size_t* olen );
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#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
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static int ssl_write_supported_groups_ext( mbedtls_ssl_context *ssl,
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unsigned char* buf,
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unsigned char* end,
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size_t* olen );
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static int ssl_write_key_shares_ext( mbedtls_ssl_context *ssl,
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unsigned char* buf,
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unsigned char* end,
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size_t* olen );
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#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
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static int ssl_client_hello_write_partial( mbedtls_ssl_context* ssl,
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unsigned char* buf, size_t buflen,
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size_t* len_without_binders,
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size_t* len_with_binders )
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{
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/* Extensions */
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/* extension_start
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* Used during extension writing where the
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* buffer pointer to the beginning of the
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* extension list must be kept to write
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* the total extension list size in the end.
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*/
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int ret;
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unsigned char* extension_start;
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size_t cur_ext_len; /* Size of the current extension */
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size_t total_ext_len; /* Size of list of extensions */
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/* Length information */
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size_t rand_bytes_len;
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size_t version_len;
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/* Buffer management */
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unsigned char* start = buf;
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unsigned char* end = buf + buflen;
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/* Ciphersuite-related variables */
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const int* ciphersuites;
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const mbedtls_ssl_ciphersuite_t* ciphersuite_info;
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size_t i; /* used to iterate through ciphersuite list */
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/* ciphersuite_start points to the start of the ciphersuite list, i.e. to the length field*/
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unsigned char* ciphersuite_start;
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size_t ciphersuite_count;
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/* Keeping track of the included extensions */
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ssl->handshake->extensions_present = MBEDTLS_SSL_EXT_NONE;
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rand_bytes_len = 32;
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/* NOTE:
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* Even for DTLS 1.3, we are writing a TLS handshake header here.
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* The actual DTLS 1.3 handshake header is inserted in
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* the record writing routine mbedtls_ssl_write_record().
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*
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* For cTLS the length, and the version field
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* are elided. The random bytes are shorter.
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*/
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version_len = 2;
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if( ssl->conf->max_major_ver == 0 )
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{
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MBEDTLS_SSL_DEBUG_MSG( 1, ( "configured max major version is invalid, "
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"consider using mbedtls_ssl_config_defaults()" ) );
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return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
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}
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ssl->major_ver = ssl->conf->min_major_ver;
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ssl->minor_ver = ssl->conf->min_minor_ver;
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/* For TLS 1.3 we use the legacy version number {0x03, 0x03}
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* instead of the true version number.
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*
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* For DTLS 1.3 we use the legacy version number
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* {254,253}.
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*
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* In cTLS the version number is elided.
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*/
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*buf++ = 0x03;
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*buf++ = 0x03;
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buflen -= version_len;
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/* Write random bytes */
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memcpy( buf, ssl->handshake->randbytes, rand_bytes_len );
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MBEDTLS_SSL_DEBUG_BUF( 3, "client hello, random bytes", buf, rand_bytes_len );
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buf += rand_bytes_len;
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buflen -= rand_bytes_len;
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/* Versions of TLS before TLS 1.3 supported a
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* "session resumption" feature which has been merged with pre-shared
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* keys in this version. A client which has a
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* cached session ID set by a pre-TLS 1.3 server SHOULD set this
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* field to that value. In compatibility mode,
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* this field MUST be non-empty, so a client not offering a
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* pre-TLS 1.3 session MUST generate a new 32-byte value. This value
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* need not be random but SHOULD be unpredictable to avoid
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* implementations fixating on a specific value ( also known as
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* ossification ). Otherwise, it MUST be set as a zero-length vector
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* ( i.e., a zero-valued single byte length field ).
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*/
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if( buflen < 1 )
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{
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MBEDTLS_SSL_DEBUG_MSG( 1, ( "buffer too small to hold ClientHello" ) );
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return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
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}
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*buf++ = 0; /* session id length set to zero */
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buflen -= 1;
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/*
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* Ciphersuite list
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*
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* This is a list of the symmetric cipher options supported by
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* the client, specifically the record protection algorithm
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* ( including secret key length ) and a hash to be used with
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* HKDF, in descending order of client preference.
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*/
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ciphersuites = ssl->conf->ciphersuite_list;
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if( buflen < 2 /* for ciphersuite list length */ )
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{
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MBEDTLS_SSL_DEBUG_MSG( 1, ( "buffer too small to hold ClientHello" ) );
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return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
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}
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/* Skip writing ciphersuite length for now */
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ciphersuite_count = 0;
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ciphersuite_start = buf;
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buf += 2;
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buflen -= 2;
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for ( i = 0; ciphersuites[i] != 0; i++ )
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{
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ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( ciphersuites[i] );
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if( ciphersuite_info == NULL )
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continue;
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if( ciphersuite_info->min_minor_ver != MBEDTLS_SSL_MINOR_VERSION_4 ||
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ciphersuite_info->max_minor_ver != MBEDTLS_SSL_MINOR_VERSION_4 )
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continue;
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MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, add ciphersuite: %04x, %s",
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(unsigned int) ciphersuites[i], ciphersuite_info->name ) );
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ciphersuite_count++;
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if( buflen < 2 /* for ciphersuite list length */ )
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{
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MBEDTLS_SSL_DEBUG_MSG( 1, ( "buffer too small to hold ClientHello" ) );
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return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
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}
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*buf++ = (unsigned char)( ciphersuites[i] >> 8 );
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*buf++ = (unsigned char)( ciphersuites[i] );
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buflen -= 2;
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}
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/* write ciphersuite length now */
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*ciphersuite_start++ = (unsigned char)( ciphersuite_count*2 >> 8 );
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*ciphersuite_start++ = (unsigned char)( ciphersuite_count*2 );
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MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, got %" MBEDTLS_PRINTF_SIZET " ciphersuites", ciphersuite_count ) );
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/* For every TLS 1.3 ClientHello, this vector MUST contain exactly
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* one byte set to zero, which corresponds to the 'null' compression
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* method in prior versions of TLS.
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*
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* For cTLS this field is elided.
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*/
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if( buflen < 2 /* for ciphersuite list length */ )
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{
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MBEDTLS_SSL_DEBUG_MSG( 1, ( "buffer too small to hold ClientHello" ) );
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return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
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}
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*buf++ = 1;
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*buf++ = MBEDTLS_SSL_COMPRESS_NULL;
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buflen -= 2;
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/* First write extensions, then the total length */
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extension_start = buf;
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total_ext_len = 0;
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buf += 2;
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/* Supported Versions Extension is mandatory with TLS 1.3.
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*
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* For cTLS we only need to provide it if there is more than one version
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* and currently there is only one.
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*/
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ssl_write_supported_versions_ext( ssl, buf, end, &cur_ext_len );
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total_ext_len += cur_ext_len;
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buf += cur_ext_len;
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#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
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/* The supported_groups and the key_share extensions are
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* REQUIRED for ECDHE ciphersuites.
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*/
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ret = ssl_write_supported_groups_ext( ssl, buf, end, &cur_ext_len );
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if( ret != 0 )
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return( ret );
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total_ext_len += cur_ext_len;
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buf += cur_ext_len;
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/* The supported_signature_algorithms extension is REQUIRED for
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* certificate authenticated ciphersuites. */
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ret = mbedtls_ssl_write_signature_algorithms_ext( ssl, buf, end, &cur_ext_len );
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if( ret != 0 )
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return( ret );
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total_ext_len += cur_ext_len;
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buf += cur_ext_len;
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/* We need to send the key shares under three conditions:
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* 1 ) A certificate-based ciphersuite is being offered. In this case
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* supported_groups and supported_signature extensions have been successfully added.
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* 2 ) A PSK-based ciphersuite with ECDHE is offered. In this case the
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* psk_key_exchange_modes has been added as the last extension.
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* 3 ) Or, in case all ciphers are supported ( which includes #1 and #2 from above )
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*/
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ret = ssl_write_key_shares_ext( ssl, buf, end, &cur_ext_len );
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if( ret != 0 )
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return( ret );
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total_ext_len += cur_ext_len;
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buf += cur_ext_len;
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#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
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/* Add more extensions here */
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MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, total extension length: %" MBEDTLS_PRINTF_SIZET ,
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total_ext_len ) );
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MBEDTLS_SSL_DEBUG_BUF( 3, "client hello extensions", extension_start, total_ext_len );
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/* Write extension length */
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*extension_start++ = (unsigned char)( ( total_ext_len >> 8 ) & 0xFF );
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*extension_start++ = (unsigned char)( ( total_ext_len ) & 0xFF );
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*len_without_binders = buf - start;
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*len_with_binders = ( extension_start + total_ext_len ) - start;
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return( 0 );
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}
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static void ssl_write_supported_versions_ext( mbedtls_ssl_context *ssl,
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unsigned char* buf,
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unsigned char* end,
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size_t* olen )
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{
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((void) ssl);
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((void) buf);
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((void) buflen);
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((void) len_without_binders);
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((void) len_with_binders);
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((void) end);
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((void) olen);
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}
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#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
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static int ssl_write_supported_groups_ext( mbedtls_ssl_context *ssl,
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unsigned char* buf,
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unsigned char* end,
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size_t* olen )
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{
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((void) ssl);
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((void) buf);
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((void) end);
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((void) olen);
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return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
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}
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static int ssl_write_key_shares_ext( mbedtls_ssl_context *ssl,
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unsigned char* buf,
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unsigned char* end,
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size_t* olen )
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{
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((void) ssl);
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((void) buf);
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((void) end);
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((void) olen);
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return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
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}
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#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
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#endif /* MBEDTLS_SSL_CLI_C */
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@ -70,6 +70,40 @@ void mbedtls_ssl_add_hs_hdr_to_checksum( mbedtls_ssl_context *ssl,
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ssl->handshake->update_checksum( ssl, hs_hdr, sizeof( hs_hdr ) );
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}
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#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
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/*
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* mbedtls_ssl_write_signature_algorithms_ext( )
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*
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* enum {
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* ....
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* ecdsa_secp256r1_sha256( 0x0403 ),
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* ecdsa_secp384r1_sha384( 0x0503 ),
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* ecdsa_secp521r1_sha512( 0x0603 ),
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* ....
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* } SignatureScheme;
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*
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* struct {
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* SignatureScheme supported_signature_algorithms<2..2^16-2>;
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* } SignatureSchemeList;
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*
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* Only if we handle at least one key exchange that needs signatures.
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*/
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int mbedtls_ssl_write_signature_algorithms_ext( mbedtls_ssl_context *ssl,
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unsigned char* buf,
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unsigned char* end,
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size_t* olen )
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{
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((void) ssl);
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((void) buf);
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((void) end);
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((void) olen);
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return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
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}
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#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
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#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
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#endif /* MBEDTLS_SSL_TLS_C */
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