add offered psks parser

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
This commit is contained in:
Jerry Yu 2022-07-10 06:32:38 +00:00
parent 6dcd18d55b
commit 1c105560b4
2 changed files with 322 additions and 8 deletions

View File

@ -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 );

View File

@ -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 );
}