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tls13:Add certificate verify

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Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
This commit is contained in:
Jerry Yu 2021-09-12 20:16:03 +08:00
parent 0bbb39786d
commit 30b071cb66
3 changed files with 382 additions and 5 deletions
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5
library/ssl_misc.h
View File

@ -1633,6 +1633,11 @@ int mbedtls_ssl_tls13_start_handshake_msg( mbedtls_ssl_context *ssl,
*/
int mbedtls_ssl_tls13_process_certificate( mbedtls_ssl_context *ssl );
/*
* Generic handler of Certificate Verify
*/
int mbedtls_ssl_tls13_process_certificate_verify( mbedtls_ssl_context *ssl );
/*
* Write TLS 1.3 handshake message tail
*/

7
library/ssl_tls13_client.c
View File

@ -1584,7 +1584,12 @@ static int ssl_tls1_3_process_server_certificate( mbedtls_ssl_context *ssl )
*/
static int ssl_tls1_3_process_certificate_verify( mbedtls_ssl_context *ssl )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "%s hasn't been implemented", __func__ ) );
int ret;
ret = mbedtls_ssl_tls13_process_certificate_verify( ssl );
if( ret != 0 )
return( ret );
mbedtls_ssl_handshake_set_state( ssl, MBEDTLS_SSL_SERVER_FINISHED );
return( 0 );
}

375
library/ssl_tls13_generic.c
View File

@ -23,14 +23,15 @@
#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
#include <string.h>
#include "mbedtls/error.h"
#include "mbedtls/debug.h"
#include "mbedtls/oid.h"
#include "mbedtls/platform.h"
#include "ssl_misc.h"
#include <mbedtls/debug.h>
#include <mbedtls/oid.h>
#include <mbedtls/platform.h>
#include "ssl_tls13_keys.h"
int mbedtls_ssl_tls1_3_fetch_handshake_msg( mbedtls_ssl_context *ssl,
unsigned hs_type,
@ -217,8 +218,374 @@ int mbedtls_ssl_tls13_write_sig_alg_ext( mbedtls_ssl_context *ssl,
return( 0 );
}
/*
* The ssl_tls13_create_verify_structure() creates the verify structure.
* As input, it requires the transcript hash.
*
* The caller has to ensure that the buffer has size at least
* SSL_VERIFY_STRUCT_MAX_SIZE bytes.
*/
static void ssl_tls13_create_verify_structure( unsigned char *transcript_hash,
size_t transcript_hash_len,
unsigned char *verify_buffer,
size_t *verify_buffer_len,
int from )
{
size_t idx = 0;
/* RFC 8446, Section 4.4.3:
*
* The digital signature [in the CertificateVerify message] is then
* computed over the concatenation of:
* - A string that consists of octet 32 (0x20) repeated 64 times
* - The context string
* - A single 0 byte which serves as the separator
* - The content to be signed
*/
uint8_t const verify_padding_val = 0x20;
size_t const verify_padding_len = 64;
memset( verify_buffer + idx, verify_padding_val, verify_padding_len );
idx += verify_padding_len;
if( from == MBEDTLS_SSL_IS_CLIENT )
{
memcpy( verify_buffer + idx, MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( client_cv ) );
idx += MBEDTLS_SSL_TLS1_3_LBL_LEN( client_cv );
}
else
{ /* from == MBEDTLS_SSL_IS_SERVER */
memcpy( verify_buffer + idx, MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( server_cv ) );
idx += MBEDTLS_SSL_TLS1_3_LBL_LEN( server_cv );
}
verify_buffer[idx++] = 0x0;
memcpy( verify_buffer + idx, transcript_hash, transcript_hash_len );
idx += transcript_hash_len;
*verify_buffer_len = idx;
}
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
/*
* STATE HANDLING: Read CertificateVerify
*/
/* Macro to express the length of the verify structure length.
*
* The structure is computed per TLS 1.3 specification as:
* - 64 bytes of octet 32,
* - 33 bytes for the context string
* (which is either "TLS 1.3, client CertificateVerify"
* or "TLS 1.3, server CertificateVerify"),
* - 1 byte for the octet 0x0, which servers as a separator,
* - 32 or 48 bytes for the Transcript-Hash(Handshake Context, Certificate)
* (depending on the size of the transcript_hash)
*
* This results in a total size of
* - 130 bytes for a SHA256-based transcript hash, or
* (64 + 33 + 1 + 32 bytes)
* - 146 bytes for a SHA384-based transcript hash.
* (64 + 33 + 1 + 48 bytes)
*
*/
#define SSL_VERIFY_STRUCT_MAX_SIZE ( 64 + \
33 + \
1 + \
MBEDTLS_MD_MAX_SIZE \
)
/* Coordinate: Check whether a certificate verify message is expected.
* Returns a negative value on failure, and otherwise
* - SSL_CERTIFICATE_VERIFY_SKIP
* - SSL_CERTIFICATE_VERIFY_READ
* to indicate if the CertificateVerify message should be present or not.
*/
#define SSL_CERTIFICATE_VERIFY_SKIP 0
#define SSL_CERTIFICATE_VERIFY_READ 1
static int ssl_tls13_process_certificate_verify_coordinate(
mbedtls_ssl_context *ssl )
{
if( mbedtls_ssl_tls1_3_some_psk_enabled( ssl ) )
return( SSL_CERTIFICATE_VERIFY_SKIP );
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
if( ssl->session_negotiate->peer_cert == NULL )
return( SSL_CERTIFICATE_VERIFY_SKIP );
return( SSL_CERTIFICATE_VERIFY_READ );
#else
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
}
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED)
static int ssl_tls13_process_certificate_verify_parse( mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end,
const unsigned char *verify_buffer,
size_t verify_buffer_len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
const unsigned char *p = buf;
uint16_t algorithm;
const uint16_t *tls13_sig_alg = ssl->conf->tls13_sig_algs;
size_t signature_len;
mbedtls_pk_type_t sig_alg;
mbedtls_md_type_t md_alg;
unsigned char verify_hash[MBEDTLS_TLS1_3_MD_MAX_SIZE];
size_t verify_hash_len;
/*
* struct {
* SignatureScheme algorithm;
* opaque signature<0..2^16-1>;
* } CertificateVerify;
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
algorithm = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
/* RFC 8446 section 4.4.3
*
* If the CertificateVerify message is sent by a server, the signature algorithm
* MUST be one offered in the client's "signature_algorithms" extension unless
* no valid certificate chain can be produced without unsupported algorithms
*
* RFC 8446 section 4.4.2.2
*
* If the client cannot construct an acceptable chain using the provided
* certificates and decides to abort the handshake, then it MUST abort the handshake
* with an appropriate certificate-related alert (by default, "unsupported_certificate").
*
* Check if algorithm in offered signature algorithms. Send `unsupported_certificate`
* alert message on failure.
*/
while( 1 )
{
/* Found algorithm in offered signature algorithms */
if( *tls13_sig_alg == algorithm )
break;
if( *tls13_sig_alg == MBEDTLS_TLS13_SIG_NONE )
{
/* End of offered signature algorithms list */
MBEDTLS_SSL_DEBUG_MSG( 1,
( "signature algorithm(%04x) not in offered"
"signature algorithms ",
( unsigned int ) algorithm ) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE;
}
tls13_sig_alg++;
}
/* We currently only support ECDSA-based signatures */
switch( algorithm )
{
case MBEDTLS_TLS13_SIG_ECDSA_SECP256R1_SHA256:
md_alg = MBEDTLS_MD_SHA256;
sig_alg = MBEDTLS_PK_ECDSA;
break;
case MBEDTLS_TLS13_SIG_ECDSA_SECP384R1_SHA384:
md_alg = MBEDTLS_MD_SHA384;
sig_alg = MBEDTLS_PK_ECDSA;
break;
case MBEDTLS_TLS13_SIG_ECDSA_SECP521R1_SHA512:
md_alg = MBEDTLS_MD_SHA512;
sig_alg = MBEDTLS_PK_ECDSA;
break;
default:
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Certificate Verify: Unknown signature algorithm." ) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
MBEDTLS_SSL_DEBUG_MSG( 3, ( "Certificate Verify: Signature algorithm ( %04x )",
( unsigned int ) algorithm ) );
/*
* Check the certificate's key type matches the signature alg
*/
if( !mbedtls_pk_can_do( &ssl->session_negotiate->peer_cert->pk, sig_alg ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "signature algorithm doesn't match cert key" ) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, 2 );
signature_len = MBEDTLS_GET_UINT16_BE( p, 0 );
p += 2;
MBEDTLS_SSL_CHK_BUF_READ_PTR( p, end, signature_len );
/* Hash verify buffer with indicated hash function */
switch( md_alg )
{
#if defined(MBEDTLS_SHA256_C)
case MBEDTLS_MD_SHA256:
verify_hash_len = 32;
if( ( ret = mbedtls_sha256( verify_buffer,
verify_buffer_len,
verify_hash,
0 ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_sha256", ret );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
break;
#endif /* MBEDTLS_SHA256_C */
#if defined(MBEDTLS_SHA384_C)
case MBEDTLS_MD_SHA384:
verify_hash_len = 48;
if( ( ret = mbedtls_sha512( verify_buffer,
verify_buffer_len,
verify_hash,
1 ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_sha384", ret );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
break;
#endif /* MBEDTLS_SHA384_C */
#if defined(MBEDTLS_SHA512_C)
case MBEDTLS_MD_SHA512:
verify_hash_len = 64;
if( ( ret = mbedtls_sha512( verify_buffer,
verify_buffer_len,
verify_hash,
0 ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_sha512", ret );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
break;
#endif /* MBEDTLS_SHA512_C */
default:
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Certificate Verify: Unknown signature algorithm." ) );
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_CERT,
MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
MBEDTLS_SSL_DEBUG_BUF( 3, "verify hash", verify_hash, verify_hash_len );
if( ( ret = mbedtls_pk_verify_ext( sig_alg, NULL,
&ssl->session_negotiate->peer_cert->pk,
md_alg, verify_hash, verify_hash_len,
buf, signature_len ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_pk_verify_ext", ret );
/* RFC 8446 section 4.4.3
*
* If the verification fails, the receiver MUST terminate the handshake
* with a "decrypt_error" alert.
*/
MBEDTLS_SSL_PEND_FATAL_ALERT( MBEDTLS_SSL_ALERT_MSG_DECRYPT_ERROR, ret );
return( ret );
}
return( ret );
}
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
int mbedtls_ssl_tls13_process_certificate_verify( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
/* Coordination step */
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse certificate verify" ) );
MBEDTLS_SSL_PROC_CHK_NEG( ssl_tls13_process_certificate_verify_coordinate( ssl ) );
#if defined(MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED) // TBD: double-check
if( ret == SSL_CERTIFICATE_VERIFY_READ )
{
unsigned char verify_buffer[SSL_VERIFY_STRUCT_MAX_SIZE];
size_t verify_buffer_len;
unsigned char transcript[MBEDTLS_TLS1_3_MD_MAX_SIZE];
size_t transcript_len;
unsigned char *buf;
size_t buf_len;
/* Need to calculate the hash of the transcript first
* before reading the message since otherwise it gets
* included in the transcript
*/
ret = mbedtls_ssl_get_handshake_transcript( ssl,
ssl->handshake->ciphersuite_info->mac,
transcript, sizeof( transcript ),
&transcript_len );
if( ret != 0 )
{
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_INTERNAL_ERROR,
MBEDTLS_ERR_SSL_INTERNAL_ERROR );
return( ret );
}
MBEDTLS_SSL_DEBUG_BUF( 3, "handshake hash", transcript, transcript_len );
/* Create verify structure */
ssl_tls13_create_verify_structure( transcript,
transcript_len,
verify_buffer,
&verify_buffer_len,
!ssl->conf->endpoint );
MBEDTLS_SSL_PROC_CHK(
mbedtls_ssl_tls1_3_fetch_handshake_msg( ssl,
MBEDTLS_SSL_HS_CERTIFICATE_VERIFY, &buf, &buf_len ) );
/* Process the message contents */
MBEDTLS_SSL_PROC_CHK(
ssl_tls13_process_certificate_verify_parse( ssl,
buf, buf + buf_len, verify_buffer, verify_buffer_len ) );
mbedtls_ssl_tls1_3_add_hs_msg_to_checksum( ssl,
MBEDTLS_SSL_HS_CERTIFICATE_VERIFY, buf, buf_len );
}
else
#endif /* MBEDTLS_KEY_EXCHANGE_WITH_CERT_ENABLED */
if( ret == SSL_CERTIFICATE_VERIFY_SKIP )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= skip parse certificate verify" ) );
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
cleanup:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse certificate verify" ) );
return( ret );
}
/*
*
* STATE HANDLING: Incoming Certificate, client-side only currently.