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Merge pull request #5454 from gstrauss/cert_cb-user_data

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server certificate selection callback
This commit is contained in:
Manuel Pégourié-Gonnard 2022-03-10 11:51:42 +01:00 committed by GitHub
commit 10e5cdbbbf
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8 changed files with 172 additions and 44 deletions
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7
ChangeLog.d/mbedtls_ssl_cert_cb.txt Normal file
View file

@ -0,0 +1,7 @@
Features
* Add server certificate selection callback near end of Client Hello.
Register callback with mbedtls_ssl_conf_cert_cb().
* Provide mechanism to reset handshake cert list by calling
mbedtls_ssl_set_hs_own_cert() with NULL value for own_cert param.
* Add accessor mbedtls_ssl_get_hs_sni() to retrieve SNI from within
cert callback (mbedtls_ssl_conf_cert_cb()) during handshake.

59
include/mbedtls/ssl.h
View file

@ -1475,6 +1475,10 @@ struct mbedtls_ssl_config
* access it afterwards.
*/
mbedtls_ssl_user_data_t MBEDTLS_PRIVATE(user_data);
#if defined(MBEDTLS_SSL_SRV_C)
int (*MBEDTLS_PRIVATE(f_cert_cb))(mbedtls_ssl_context *); /*!< certificate selection callback */
#endif /* MBEDTLS_SSL_SRV_C */
};
struct mbedtls_ssl_context
@ -2220,6 +2224,28 @@ void mbedtls_ssl_set_timer_cb( mbedtls_ssl_context *ssl,
mbedtls_ssl_set_timer_t *f_set_timer,
mbedtls_ssl_get_timer_t *f_get_timer );
#if defined(MBEDTLS_SSL_SRV_C)
/**
* \brief Set the certificate selection callback (server-side only).
*
* If set, the callback is always called for each handshake,
* after `ClientHello` processing has finished.
*
* The callback has the following parameters:
* - \c mbedtls_ssl_context*: The SSL context to which
* the operation applies.
* The return value of the callback is 0 if successful,
* or a specific MBEDTLS_ERR_XXX code, which will cause
* the handshake to be aborted.
*
* \param conf The SSL configuration to register the callback with.
* \param f_cert_cb The callback for selecting server certificate after
* `ClientHello` processing has finished.
*/
void mbedtls_ssl_conf_cert_cb( mbedtls_ssl_config *conf,
int (*f_cert_cb)(mbedtls_ssl_context *) );
#endif /* MBEDTLS_SSL_SRV_C */
/**
* \brief Callback type: generate and write session ticket
*
@ -3514,11 +3540,35 @@ int mbedtls_ssl_set_hostname( mbedtls_ssl_context *ssl, const char *hostname );
#endif /* MBEDTLS_X509_CRT_PARSE_C */
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
/**
* \brief Retrieve SNI extension value for the current handshake.
* Available in \p f_cert_cb of \c mbedtls_ssl_conf_cert_cb(),
* this is the same value passed to \p f_sni callback of
* \c mbedtls_ssl_conf_sni() and may be used instead of
* \c mbedtls_ssl_conf_sni().
*
* \param ssl SSL context
* \param name_len pointer into which to store length of returned value.
* 0 if SNI extension is not present or not yet processed.
*
* \return const pointer to SNI extension value.
* - value is valid only when called in \p f_cert_cb
* registered with \c mbedtls_ssl_conf_cert_cb().
* - value is NULL if SNI extension is not present.
* - value is not '\0'-terminated. Use \c name_len for len.
* - value must not be freed.
*/
const unsigned char *mbedtls_ssl_get_hs_sni( mbedtls_ssl_context *ssl,
size_t *name_len );
/**
* \brief Set own certificate and key for the current handshake
*
* \note Same as \c mbedtls_ssl_conf_own_cert() but for use within
* the SNI callback.
* the SNI callback or the certificate selection callback.
*
* \note Passing null \c own_cert clears the certificate list for
* the current handshake.
*
* \param ssl SSL context
* \param own_cert own public certificate chain
@ -3535,7 +3585,7 @@ int mbedtls_ssl_set_hs_own_cert( mbedtls_ssl_context *ssl,
* current handshake
*
* \note Same as \c mbedtls_ssl_conf_ca_chain() but for use within
* the SNI callback.
* the SNI callback or the certificate selection callback.
*
* \param ssl SSL context
* \param ca_chain trusted CA chain (meaning all fully trusted top-level CAs)
@ -3549,7 +3599,7 @@ void mbedtls_ssl_set_hs_ca_chain( mbedtls_ssl_context *ssl,
* \brief Set authmode for the current handshake.
*
* \note Same as \c mbedtls_ssl_conf_authmode() but for use within
* the SNI callback.
* the SNI callback or the certificate selection callback.
*
* \param ssl SSL context
* \param authmode MBEDTLS_SSL_VERIFY_NONE, MBEDTLS_SSL_VERIFY_OPTIONAL or
@ -3574,8 +3624,7 @@ void mbedtls_ssl_set_hs_authmode( mbedtls_ssl_context *ssl,
* mbedtls_ssl_set_hs_ca_chain() as well as the client
* authentication mode with \c mbedtls_ssl_set_hs_authmode(),
* then must return 0. If no matching name is found, the
* callback must either set a default cert, or
* return non-zero to abort the handshake at this point.
* callback may return non-zero to abort the handshake.
*
* \param conf SSL configuration
* \param f_sni verification function

5
library/ssl_misc.h
View file

@ -850,6 +850,11 @@ struct mbedtls_ssl_handshake_params
* The library does not use it internally. */
void *user_async_ctx;
#endif /* MBEDTLS_SSL_ASYNC_PRIVATE */
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
const unsigned char *sni_name; /*!< raw SNI */
size_t sni_name_len; /*!< raw SNI len */
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
};
typedef struct mbedtls_ssl_hs_buffer mbedtls_ssl_hs_buffer;

24
library/ssl_srv.c
View file

@ -118,6 +118,11 @@ static int ssl_parse_servername_ext( mbedtls_ssl_context *ssl,
if( p[0] == MBEDTLS_TLS_EXT_SERVERNAME_HOSTNAME )
{
ssl->handshake->sni_name = p + 3;
ssl->handshake->sni_name_len = hostname_len;
if( ssl->conf->f_sni == NULL )
return( 0 );
ret = ssl->conf->f_sni( ssl->conf->p_sni,
ssl, p + 3, hostname_len );
if( ret != 0 )
@ -1643,9 +1648,6 @@ read_record_header:
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
case MBEDTLS_TLS_EXT_SERVERNAME:
MBEDTLS_SSL_DEBUG_MSG( 3, ( "found ServerName extension" ) );
if( ssl->conf->f_sni == NULL )
break;
ret = ssl_parse_servername_ext( ssl, ext + 4, ext_size );
if( ret != 0 )
return( ret );
@ -1870,10 +1872,24 @@ read_record_header:
return( MBEDTLS_ERR_SSL_HANDSHAKE_FAILURE );
}
/*
* Server certification selection (after processing TLS extensions)
*/
if( ssl->conf->f_cert_cb && ( ret = ssl->conf->f_cert_cb( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "f_cert_cb", ret );
return( ret );
}
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
ssl->handshake->sni_name = NULL;
ssl->handshake->sni_name_len = 0;
#endif
/*
* Search for a matching ciphersuite
* (At the end because we need information from the EC-based extensions
* and certificate from the SNI callback triggered by the SNI extension.)
* and certificate from the SNI callback triggered by the SNI extension
* or certificate from server certificate selection callback.)
*/
got_common_suite = 0;
ciphersuites = ssl->conf->ciphersuite_list;

63
library/ssl_tls.c
View file

@ -1232,6 +1232,14 @@ void mbedtls_ssl_set_timer_cb( mbedtls_ssl_context *ssl,
mbedtls_ssl_set_timer( ssl, 0 );
}
#if defined(MBEDTLS_SSL_SRV_C)
void mbedtls_ssl_conf_cert_cb( mbedtls_ssl_config *conf,
int (*f_cert_cb)(mbedtls_ssl_context *) )
{
conf->f_cert_cb = f_cert_cb;
}
#endif /* MBEDTLS_SSL_SRV_C */
#if defined(MBEDTLS_SSL_SRV_C)
void mbedtls_ssl_conf_session_cache( mbedtls_ssl_config *conf,
void *p_cache,
@ -1291,6 +1299,18 @@ void mbedtls_ssl_conf_cert_profile( mbedtls_ssl_config *conf,
conf->cert_profile = profile;
}
static void ssl_key_cert_free( mbedtls_ssl_key_cert *key_cert )
{
mbedtls_ssl_key_cert *cur = key_cert, *next;
while( cur != NULL )
{
next = cur->next;
mbedtls_free( cur );
cur = next;
}
}
/* Append a new keycert entry to a (possibly empty) list */
static int ssl_append_key_cert( mbedtls_ssl_key_cert **head,
mbedtls_x509_crt *cert,
@ -1298,6 +1318,14 @@ static int ssl_append_key_cert( mbedtls_ssl_key_cert **head,
{
mbedtls_ssl_key_cert *new_cert;
if( cert == NULL )
{
/* Free list if cert is null */
ssl_key_cert_free( *head );
*head = NULL;
return( 0 );
}
new_cert = mbedtls_calloc( 1, sizeof( mbedtls_ssl_key_cert ) );
if( new_cert == NULL )
return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
@ -1306,7 +1334,7 @@ static int ssl_append_key_cert( mbedtls_ssl_key_cert **head,
new_cert->key = key;
new_cert->next = NULL;
/* Update head is the list was null, else add to the end */
/* Update head if the list was null, else add to the end */
if( *head == NULL )
{
*head = new_cert;
@ -1361,6 +1389,13 @@ void mbedtls_ssl_conf_ca_cb( mbedtls_ssl_config *conf,
#endif /* MBEDTLS_X509_CRT_PARSE_C */
#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
const unsigned char *mbedtls_ssl_get_hs_sni( mbedtls_ssl_context *ssl,
size_t *name_len )
{
*name_len = ssl->handshake->sni_name_len;
return( ssl->handshake->sni_name );
}
int mbedtls_ssl_set_hs_own_cert( mbedtls_ssl_context *ssl,
mbedtls_x509_crt *own_cert,
mbedtls_pk_context *pk_key )
@ -2941,20 +2976,6 @@ int mbedtls_ssl_renegotiate( mbedtls_ssl_context *ssl )
}
#endif /* MBEDTLS_SSL_RENEGOTIATION */
#if defined(MBEDTLS_X509_CRT_PARSE_C)
static void ssl_key_cert_free( mbedtls_ssl_key_cert *key_cert )
{
mbedtls_ssl_key_cert *cur = key_cert, *next;
while( cur != NULL )
{
next = cur->next;
mbedtls_free( cur );
cur = next;
}
}
#endif /* MBEDTLS_X509_CRT_PARSE_C */
void mbedtls_ssl_handshake_free( mbedtls_ssl_context *ssl )
{
mbedtls_ssl_handshake_params *handshake = ssl->handshake;
@ -3042,17 +3063,7 @@ void mbedtls_ssl_handshake_free( mbedtls_ssl_context *ssl )
* Free only the linked list wrapper, not the keys themselves
* since the belong to the SNI callback
*/
if( handshake->sni_key_cert != NULL )
{
mbedtls_ssl_key_cert *cur = handshake->sni_key_cert, *next;
while( cur != NULL )
{
next = cur->next;
mbedtls_free( cur );
cur = next;
}
}
ssl_key_cert_free( handshake->sni_key_cert );
#endif /* MBEDTLS_X509_CRT_PARSE_C && MBEDTLS_SSL_SERVER_NAME_INDICATION */
#if defined(MBEDTLS_SSL_ECP_RESTARTABLE_ENABLED)

47
programs/ssl/ssl_server2.c
View file

@ -823,18 +823,23 @@ int sni_callback( void *p_info, mbedtls_ssl_context *ssl,
{
const sni_entry *cur = (const sni_entry *) p_info;
/* preserve behavior which checks for SNI match in sni_callback() for
* the benefits of tests using sni_callback(), even though the actual
* certificate assignment has moved to certificate selection callback
* in this application. This exercises sni_callback and cert_callback
* even though real applications might choose to do this differently.
* Application might choose to save name and name_len in user_data for
* later use in certificate selection callback.
*/
while( cur != NULL )
{
if( name_len == strlen( cur->name ) &&
memcmp( name, cur->name, name_len ) == 0 )
{
if( cur->ca != NULL )
mbedtls_ssl_set_hs_ca_chain( ssl, cur->ca, cur->crl );
if( cur->authmode != DFL_AUTH_MODE )
mbedtls_ssl_set_hs_authmode( ssl, cur->authmode );
return( mbedtls_ssl_set_hs_own_cert( ssl, cur->cert, cur->key ) );
void *p;
*(const void **)&p = cur;
mbedtls_ssl_set_user_data_p( ssl, p );
return( 0 );
}
cur = cur->next;
@ -843,6 +848,33 @@ int sni_callback( void *p_info, mbedtls_ssl_context *ssl,
return( -1 );
}
/*
* server certificate selection callback.
*/
int cert_callback( mbedtls_ssl_context *ssl )
{
const sni_entry *cur = (sni_entry *) mbedtls_ssl_get_user_data_p( ssl );
if( cur != NULL )
{
/*(exercise mbedtls_ssl_get_hs_sni(); not otherwise used here)*/
size_t name_len;
const unsigned char *name = mbedtls_ssl_get_hs_sni( ssl, &name_len );
if( strlen( cur->name ) != name_len ||
memcmp( cur->name, name, name_len ) != 0 )
return( MBEDTLS_ERR_SSL_DECODE_ERROR );
if( cur->ca != NULL )
mbedtls_ssl_set_hs_ca_chain( ssl, cur->ca, cur->crl );
if( cur->authmode != DFL_AUTH_MODE )
mbedtls_ssl_set_hs_authmode( ssl, cur->authmode );
return( mbedtls_ssl_set_hs_own_cert( ssl, cur->cert, cur->key ) );
}
return( 0 );
}
#endif /* SNI_OPTION */
#if defined(MBEDTLS_KEY_EXCHANGE_SOME_PSK_ENABLED)
@ -2923,6 +2955,7 @@ int main( int argc, char *argv[] )
if( opt.sni != NULL )
{
mbedtls_ssl_conf_sni( &conf, sni_callback, sni_info );
mbedtls_ssl_conf_cert_cb( &conf, cert_callback );
#if defined(MBEDTLS_SSL_ASYNC_PRIVATE)
if( opt.async_private_delay2 >= 0 )
{

2
tests/ssl-opt.sh
View file

@ -5025,7 +5025,6 @@ run_test "SNI: no SNI callback" \
crt_file=data_files/server5.crt key_file=data_files/server5.key" \
"$P_CLI server_name=localhost" \
0 \
-S "parse ServerName extension" \
-c "issuer name *: C=NL, O=PolarSSL, CN=Polarssl Test EC CA" \
-c "subject name *: C=NL, O=PolarSSL, CN=localhost"
@ -5175,7 +5174,6 @@ run_test "SNI: DTLS, no SNI callback" \
crt_file=data_files/server5.crt key_file=data_files/server5.key" \
"$P_CLI server_name=localhost dtls=1" \
0 \
-S "parse ServerName extension" \
-c "issuer name *: C=NL, O=PolarSSL, CN=Polarssl Test EC CA" \
-c "subject name *: C=NL, O=PolarSSL, CN=localhost"

9
tests/suites/test_suite_ssl.function
View file

@ -854,6 +854,15 @@ int mbedtls_endpoint_certificate_init( mbedtls_endpoint *ep, int pk_alg )
ret = mbedtls_ssl_conf_own_cert( &( ep->conf ), &( cert->cert ),
&( cert->pkey ) );
TEST_ASSERT( ret == 0 );
TEST_ASSERT( ep->conf.key_cert != NULL );
ret = mbedtls_ssl_conf_own_cert( &( ep->conf ), NULL, NULL );
TEST_ASSERT( ret == 0 );
TEST_ASSERT( ep->conf.key_cert == NULL );
ret = mbedtls_ssl_conf_own_cert( &( ep->conf ), &( cert->cert ),
&( cert->pkey ) );
TEST_ASSERT( ret == 0 );
exit:
if( ret != 0 )