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Address comments in psk client review

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Improve comments
Refine cipher suite related code in psk
Refine get_psk_offered()

Change-Id: Ic3b0b5f86eb1e71f11bb499961aa8494284f1840
Signed-off-by: XiaokangQian <xiaokang.qian@arm.com>
This commit is contained in:
XiaokangQian 2022-07-14 07:54:01 +00:00 committed by Ronald Cron
parent eb69aee6af
commit 008d2bf80b
4 changed files with 97 additions and 134 deletions

2
library/ssl_client.c

@ -653,7 +653,7 @@ static int ssl_write_client_hello_body( mbedtls_ssl_context *ssl,
return( ret ); return( ret );
p += output_len; p += output_len;
} }
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 || MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */ #endif /* MBEDTLS_SSL_PROTO_TLS1_3 && MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
/* Write the length of the list of extensions. */ /* Write the length of the list of extensions. */
extensions_len = p - p_extensions_len - 2; extensions_len = p - p_extensions_len - 2;

39
library/ssl_misc.h

@ -2423,34 +2423,11 @@ int mbedtls_ssl_check_dtls_clihlo_cookie(
/* Check if we have any PSK to offer, returns 0 if PSK is available. /* Check if we have any PSK to offer, returns 0 if PSK is available.
* Assign the psk and ticket if pointers are present. * Assign the psk and ticket if pointers are present.
*/ */
static inline int mbedtls_ssl_get_psk_to_offer( int mbedtls_ssl_get_psk_to_offer(
const mbedtls_ssl_context *ssl, const mbedtls_ssl_context *ssl,
int *psk_type,
const unsigned char **psk, size_t *psk_len, const unsigned char **psk, size_t *psk_len,
const unsigned char **psk_identity, size_t *psk_identity_len ) const unsigned char **psk_identity, size_t *psk_identity_len );
{
int ptrs_present = 0;
if( psk != NULL && psk_len != NULL &&
psk_identity != NULL && psk_identity_len != NULL )
{
ptrs_present = 1;
}
/* Check if an external PSK has been configured. */
if( ssl->conf->psk != NULL )
{
if( ptrs_present )
{
*psk = ssl->conf->psk;
*psk_len = ssl->conf->psk_len;
*psk_identity = ssl->conf->psk_identity;
*psk_identity_len = ssl->conf->psk_identity_len;
}
return( 0 );
}
return( 1 );
}
/** /**
* \brief Given an SSL context and its associated configuration, write the TLS * \brief Given an SSL context and its associated configuration, write the TLS
@ -2459,9 +2436,11 @@ static inline int mbedtls_ssl_get_psk_to_offer(
* \param[in] ssl SSL context * \param[in] ssl SSL context
* \param[in] buf Base address of the buffer where to write the extension * \param[in] buf Base address of the buffer where to write the extension
* \param[in] end End address of the buffer where to write the extension * \param[in] end End address of the buffer where to write the extension
* \param[out] out_len Length of the data written into the buffer \p buf * \param[out] out_len Length in bytes of the Pre-Shared key extension: data
* written into the buffer \p buf by this function plus
* the length of the binders to be written.
* \param[out] binders_len Length of the binders to be written at the end of * \param[out] binders_len Length of the binders to be written at the end of
* extension * the extension.
*/ */
int mbedtls_ssl_tls13_write_pre_shared_key_ext_without_binders( int mbedtls_ssl_tls13_write_pre_shared_key_ext_without_binders(
mbedtls_ssl_context *ssl, mbedtls_ssl_context *ssl,
@ -2474,8 +2453,8 @@ int mbedtls_ssl_tls13_write_pre_shared_key_ext_without_binders(
* ClientHello. * ClientHello.
* *
* \param[in] ssl SSL context * \param[in] ssl SSL context
* \param[in] buf Base address of the buffer where to write the extension * \param[in] buf Base address of the buffer where to write the binders
* \param[in] end End address of the buffer where to write the extension * \param[in] end End address of the buffer where to write the binders
*/ */
int mbedtls_ssl_tls13_write_pre_shared_key_ext_binders( int mbedtls_ssl_tls13_write_pre_shared_key_ext_binders(
mbedtls_ssl_context *ssl, mbedtls_ssl_context *ssl,

152
library/ssl_tls13_client.c

@ -615,15 +615,16 @@ static int ssl_tls13_write_psk_key_exchange_modes_ext( mbedtls_ssl_context *ssl,
const unsigned char *psk_identity; const unsigned char *psk_identity;
size_t psk_identity_len; size_t psk_identity_len;
unsigned char *p = buf; unsigned char *p = buf;
int num_modes = 0; int ke_modes_len = 0;
((void) num_modes ); ((void) ke_modes_len );
*out_len = 0; *out_len = 0;
/* Skip writing extension if no PSK key exchange mode /* Skip writing extension if no PSK key exchange mode
* is enabled in the config. * is enabled in the config or there is no PSK to offer.
*/ */
if( !mbedtls_ssl_conf_tls13_some_psk_enabled( ssl ) || if( !mbedtls_ssl_conf_tls13_some_psk_enabled( ssl ) ||
mbedtls_ssl_get_psk_to_offer( ssl, &psk, &psk_len, mbedtls_ssl_get_psk_to_offer( ssl, NULL, &psk, &psk_len,
&psk_identity, &psk_identity_len ) != 0 ) &psk_identity, &psk_identity_len ) != 0 )
{ {
MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip psk_key_exchange_modes extension" ) ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip psk_key_exchange_modes extension" ) );
@ -637,18 +638,17 @@ static int ssl_tls13_write_psk_key_exchange_modes_ext( mbedtls_ssl_context *ssl,
MBEDTLS_SSL_DEBUG_MSG( MBEDTLS_SSL_DEBUG_MSG(
3, ( "client hello, adding psk_key_exchange_modes extension" ) ); 3, ( "client hello, adding psk_key_exchange_modes extension" ) );
/* Extension Type */
MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES, p, 0 ); MBEDTLS_PUT_UINT16_BE( MBEDTLS_TLS_EXT_PSK_KEY_EXCHANGE_MODES, p, 0 );
/* Skip extension length (2 byte) and /* Skip extension length (2 bytes) and
* PSK mode list length (1 byte) for now. * ke_modes length (1 byte) for now.
*/ */
p += 5; p += 5;
if( mbedtls_ssl_conf_tls13_psk_enabled( ssl ) ) if( mbedtls_ssl_conf_tls13_psk_enabled( ssl ) )
{ {
*p++ = MBEDTLS_SSL_TLS1_3_PSK_MODE_PURE; *p++ = MBEDTLS_SSL_TLS1_3_PSK_MODE_PURE;
num_modes++; ke_modes_len++;
MBEDTLS_SSL_DEBUG_MSG( 4, ( "Adding pure PSK key exchange mode" ) ); MBEDTLS_SSL_DEBUG_MSG( 4, ( "Adding pure PSK key exchange mode" ) );
} }
@ -656,17 +656,14 @@ static int ssl_tls13_write_psk_key_exchange_modes_ext( mbedtls_ssl_context *ssl,
if( mbedtls_ssl_conf_tls13_psk_ephemeral_enabled( ssl ) ) if( mbedtls_ssl_conf_tls13_psk_ephemeral_enabled( ssl ) )
{ {
*p++ = MBEDTLS_SSL_TLS1_3_PSK_MODE_ECDHE; *p++ = MBEDTLS_SSL_TLS1_3_PSK_MODE_ECDHE;
num_modes++; ke_modes_len++;
MBEDTLS_SSL_DEBUG_MSG( 4, ( "Adding PSK-ECDHE key exchange mode" ) ); MBEDTLS_SSL_DEBUG_MSG( 4, ( "Adding PSK-ECDHE key exchange mode" ) );
} }
/* Add extension length: PSK mode list length byte + actual /* Now write the extension and ke_modes length */
* PSK mode list length MBEDTLS_PUT_UINT16_BE( ke_modes_len + 1, buf, 2 );
*/ buf[4] = ke_modes_len;
MBEDTLS_PUT_UINT16_BE( num_modes + 1, buf, 2 );
/* Add PSK mode list length */
buf[4] = num_modes;
*out_len = p - buf; *out_len = p - buf;
ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES; ssl->handshake->extensions_present |= MBEDTLS_SSL_EXT_PSK_KEY_EXCHANGE_MODES;
@ -685,22 +682,12 @@ static int ssl_tls13_write_psk_key_exchange_modes_ext( mbedtls_ssl_context *ssl,
* opaque PskBinderEntry<32..255>; * opaque PskBinderEntry<32..255>;
* *
* struct { * struct {
* select ( Handshake.msg_type ) {
* *
* case client_hello: * PskIdentity identities<7..2^16-1>;
* PskIdentity identities<7..2^16-1>; * PskBinderEntry binders<33..2^16-1>;
* PskBinderEntry binders<33..2^16-1>;
*
* case server_hello:
* uint16 selected_identity;
* };
* *
* } PreSharedKeyExtension; * } PreSharedKeyExtension;
* *
*
* part = 0 ==> everything up to the PSK binder list,
* returning the binder list length in `binder_list_length`.
* part = 1 ==> the PSK binder list
*/ */
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED) #if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
@ -715,12 +702,12 @@ int mbedtls_ssl_tls13_write_pre_shared_key_ext_without_binders(
size_t psk_len; size_t psk_len;
const unsigned char *psk_identity; const unsigned char *psk_identity;
size_t psk_identity_len; size_t psk_identity_len;
const mbedtls_ssl_ciphersuite_t *suite_info = NULL; const mbedtls_ssl_ciphersuite_t *ciphersuite_info = NULL;
const int *ciphersuites; const int *ciphersuites;
psa_algorithm_t psa_hash_alg;
int hash_len = 0; int hash_len = 0;
size_t identities_len, l_binders_len; size_t identities_len, l_binders_len;
uint32_t obfuscated_ticket_age = 0; uint32_t obfuscated_ticket_age = 0;
psa_algorithm_t psa_hash_alg;
*out_len = 0; *out_len = 0;
*binders_len = 0; *binders_len = 0;
@ -738,7 +725,7 @@ int mbedtls_ssl_tls13_write_pre_shared_key_ext_without_binders(
* - Otherwise, skip the PSK extension. * - Otherwise, skip the PSK extension.
*/ */
if( mbedtls_ssl_get_psk_to_offer( ssl, &psk, &psk_len, if( mbedtls_ssl_get_psk_to_offer( ssl, NULL, &psk, &psk_len,
&psk_identity, &psk_identity_len ) != 0 ) &psk_identity, &psk_identity_len ) != 0 )
{ {
MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip pre_shared_key extensions" ) ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip pre_shared_key extensions" ) );
@ -751,22 +738,27 @@ int mbedtls_ssl_tls13_write_pre_shared_key_ext_without_binders(
ciphersuites = ssl->conf->ciphersuite_list; ciphersuites = ssl->conf->ciphersuite_list;
for ( int i = 0; ciphersuites[i] != 0; i++ ) for ( int i = 0; ciphersuites[i] != 0; i++ )
{ {
suite_info = mbedtls_ssl_ciphersuite_from_id( ciphersuites[i] ); ciphersuite_info = mbedtls_ssl_ciphersuite_from_id( ciphersuites[i] );
if( suite_info == NULL ) if( mbedtls_ssl_validate_ciphersuite(
ssl, ciphersuite_info,
MBEDTLS_SSL_VERSION_TLS1_3,
MBEDTLS_SSL_VERSION_TLS1_3 ) != 0 )
continue; continue;
/* In this implementation we only add one pre-shared-key extension. */ /* In this implementation we only add one pre-shared-key extension. */
ssl->session_negotiate->ciphersuite = ciphersuites[i]; ssl->session_negotiate->ciphersuite = ciphersuites[i];
ssl->handshake->ciphersuite_info = suite_info;
break; break;
} }
if( suite_info != NULL ) ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(
{ ssl->session_negotiate->ciphersuite );
psa_hash_alg = mbedtls_psa_translate_md( suite_info->mac ); /* No suitable ciphersuite for the PSK */
hash_len = PSA_HASH_LENGTH( psa_hash_alg ); if( ciphersuite_info == NULL )
} return( 0 );
psa_hash_alg = mbedtls_psa_translate_md( ciphersuite_info->mac );
hash_len = PSA_HASH_LENGTH( psa_hash_alg );
if( hash_len == -1 ) if( hash_len == -1 )
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
@ -818,64 +810,28 @@ int mbedtls_ssl_tls13_write_pre_shared_key_ext_binders(
{ {
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED; int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *p = buf; unsigned char *p = buf;
const mbedtls_ssl_ciphersuite_t *suite_info = NULL; const mbedtls_ssl_ciphersuite_t *ciphersuite_info = NULL;
const int *ciphersuites; psa_algorithm_t psa_hash_alg;
int hash_len = 0; int hash_len = 0;
const unsigned char *psk; const unsigned char *psk = NULL;
size_t psk_len; size_t psk_len = 0;
const unsigned char *psk_identity;
size_t psk_identity_len;
int psk_type; int psk_type;
unsigned char transcript[MBEDTLS_MD_MAX_SIZE]; unsigned char transcript[MBEDTLS_MD_MAX_SIZE];
size_t transcript_len; size_t transcript_len;
psa_algorithm_t psa_hash_alg;
/* Check if we have any PSKs to offer. If so, return the first. ciphersuite_info = mbedtls_ssl_ciphersuite_from_id(
* ssl->session_negotiate->ciphersuite );
* NOTE: Ultimately, we want to be able to offer multiple PSKs, if( ciphersuite_info == NULL )
* in which case we want to iterate over them here. return( 0 );
*
* As it stands, however, we only ever offer one, chosen
* by the following heuristic:
* - If a ticket has been configured, offer the corresponding PSK.
* - If no ticket has been configured by an external PSK has been
* configured, offer that.
* - Otherwise, skip the PSK extension.
*/
if( mbedtls_ssl_get_psk_to_offer( ssl, &psk, &psk_len, psa_hash_alg = mbedtls_psa_translate_md( ciphersuite_info->mac );
&psk_identity, &psk_identity_len ) != 0 ) hash_len = PSA_HASH_LENGTH( psa_hash_alg );
{
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
/*
* Ciphersuite list
*/
ciphersuites = ssl->conf->ciphersuite_list;
for ( int i = 0; ciphersuites[i] != 0; i++ )
{
suite_info = mbedtls_ssl_ciphersuite_from_id( ciphersuites[i] );
if( suite_info == NULL )
continue;
/* In this implementation we only add one pre-shared-key extension. */
ssl->session_negotiate->ciphersuite = ciphersuites[i];
ssl->handshake->ciphersuite_info = suite_info;
break;
}
if( suite_info != NULL )
{
psa_hash_alg = mbedtls_psa_translate_md( suite_info->mac );
hash_len = PSA_HASH_LENGTH( psa_hash_alg );
}
if( ( hash_len == -1 ) || ( ( end - buf ) != 3 + hash_len ) ) if( ( hash_len == -1 ) || ( ( end - buf ) != 3 + hash_len ) )
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR ); return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding PSK binder list" ) ); MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding PSK binder list" ) );
MBEDTLS_SSL_CHK_BUF_PTR( p, end, 3 + hash_len );
/* 2 bytes length field for array of psk binders */ /* 2 bytes length field for array of psk binders */
MBEDTLS_PUT_UINT16_BE( hash_len + 1, p, 0 ); MBEDTLS_PUT_UINT16_BE( hash_len + 1, p, 0 );
p += 2; p += 2;
@ -889,14 +845,14 @@ int mbedtls_ssl_tls13_write_pre_shared_key_ext_binders(
psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL; psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL;
/* Get current state of handshake transcript. */ /* Get current state of handshake transcript. */
ret = mbedtls_ssl_get_handshake_transcript( ssl, suite_info->mac, ret = mbedtls_ssl_get_handshake_transcript( ssl, ciphersuite_info->mac,
transcript, sizeof( transcript ), transcript, sizeof( transcript ),
&transcript_len ); &transcript_len );
if( ret != 0 ) if( ret != 0 )
return( ret ); return( ret );
ret = mbedtls_ssl_tls13_create_psk_binder( ssl, ret = mbedtls_ssl_tls13_create_psk_binder( ssl,
mbedtls_psa_translate_md( suite_info->mac ), mbedtls_psa_translate_md( ciphersuite_info->mac ),
psk, psk_len, psk_type, psk, psk_len, psk_type,
transcript, p ); transcript, p );
if( ret != 0 ) if( ret != 0 )
@ -1269,13 +1225,8 @@ static int ssl_tls13_check_server_hello_session_id_echo( mbedtls_ssl_context *ss
* opaque PskBinderEntry<32..255>; * opaque PskBinderEntry<32..255>;
* *
* struct { * struct {
* select ( Handshake.msg_type ) { *
* case client_hello: * uint16 selected_identity;
* PskIdentity identities<7..2^16-1>;
* PskBinderEntry binders<33..2^16-1>;
* case server_hello:
* uint16 selected_identity;
* };
* *
* } PreSharedKeyExtension; * } PreSharedKeyExtension;
* *
@ -1283,7 +1234,7 @@ static int ssl_tls13_check_server_hello_session_id_echo( mbedtls_ssl_context *ss
static int ssl_tls13_parse_server_psk_identity_ext( mbedtls_ssl_context *ssl, static int ssl_tls13_parse_server_psk_identity_ext( mbedtls_ssl_context *ssl,
const unsigned char *buf, const unsigned char *buf,
size_t len ) const unsigned char *end )
{ {
int ret = 0; int ret = 0;
size_t selected_identity; size_t selected_identity;
@ -1299,7 +1250,7 @@ static int ssl_tls13_parse_server_psk_identity_ext( mbedtls_ssl_context *ssl,
* NOTE: Ultimately, we want to offer multiple PSKs, and in this * NOTE: Ultimately, we want to offer multiple PSKs, and in this
* case, we need to iterate over them here. * case, we need to iterate over them here.
*/ */
if( mbedtls_ssl_get_psk_to_offer( ssl, &psk, &psk_len, if( mbedtls_ssl_get_psk_to_offer( ssl, NULL, &psk, &psk_len,
&psk_identity, &psk_identity_len ) != 0 ) &psk_identity, &psk_identity_len ) != 0 )
{ {
/* If we haven't offered a PSK, the server must not send /* If we haven't offered a PSK, the server must not send
@ -1307,12 +1258,7 @@ static int ssl_tls13_parse_server_psk_identity_ext( mbedtls_ssl_context *ssl,
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE ); return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
} }
if( len != (size_t) 2 ) MBEDTLS_SSL_CHK_BUF_PTR( buf, end, 2 );
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad psk_identity extension in server hello message" ) );
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
}
selected_identity = MBEDTLS_GET_UINT16_BE( buf, 0 ); selected_identity = MBEDTLS_GET_UINT16_BE( buf, 0 );
/* We have offered only one PSK, so the only valid choice /* We have offered only one PSK, so the only valid choice
@ -1571,7 +1517,7 @@ static int ssl_tls13_parse_server_hello( mbedtls_ssl_context *ssl,
} }
if( ( ret = ssl_tls13_parse_server_psk_identity_ext( if( ( ret = ssl_tls13_parse_server_psk_identity_ext(
ssl, p, extension_data_len ) ) != 0 ) ssl, p, extension_data_end ) ) != 0 )
{ {
MBEDTLS_SSL_DEBUG_RET( MBEDTLS_SSL_DEBUG_RET(
1, ( "ssl_tls13_parse_server_psk_identity_ext" ), ret ); 1, ( "ssl_tls13_parse_server_psk_identity_ext" ), ret );

38
library/ssl_tls13_generic.c

@ -1505,4 +1505,42 @@ int mbedtls_ssl_tls13_generate_and_write_ecdh_key_exchange(
} }
#endif /* MBEDTLS_ECDH_C */ #endif /* MBEDTLS_ECDH_C */
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
/* Check if we have any PSK to offer, returns 0 if PSK is available.
* Assign the psk and ticket if pointers are present.
*/
int mbedtls_ssl_get_psk_to_offer(
const mbedtls_ssl_context *ssl,
int *psk_type,
const unsigned char **psk, size_t *psk_len,
const unsigned char **psk_identity, size_t *psk_identity_len )
{
int ptrs_present = 0;
if( psk != NULL && psk_len != NULL &&
psk_identity != NULL && psk_identity_len != NULL )
{
ptrs_present = 1;
}
/* Check if an external PSK has been configured. */
if( ssl->conf->psk != NULL )
{
if( ptrs_present )
{
*psk = ssl->conf->psk;
*psk_len = ssl->conf->psk_len;
*psk_identity = ssl->conf->psk_identity;
*psk_identity_len = ssl->conf->psk_identity_len;
}
if( psk_type != NULL )
*psk_type = MBEDTLS_SSL_TLS1_3_PSK_EXTERNAL;
return( 0 );
}
return( 1 );
}
#endif /* MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED */
#endif /* MBEDTLS_SSL_TLS_C && MBEDTLS_SSL_PROTO_TLS1_3 */ #endif /* MBEDTLS_SSL_TLS_C && MBEDTLS_SSL_PROTO_TLS1_3 */