commit 14d11b0877ffecc42dae531afe17570f0e61b7e6
author Przemek Stekiel <przemyslaw.stekiel@mobica.com> Thu Apr 14 08:33:29 2022 +0200
committer Przemek Stekiel <przemyslaw.stekiel@mobica.com> Fri Apr 22 14:53:55 2022 +0200
tree 62aa213b9e4085b769de29e4419a34d7e9e09db7
parent 19b80f8151c861138461e5ea31841d15d968f5c4

Enable support for psa opaque ECDHE-PSK key exchange on the server side

Signed-off-by: Przemek Stekiel <przemyslaw.stekiel@mobica.com>

library/ssl_tls12_server.c

diff --git a/library/ssl_tls12_server.c b/library/ssl_tls12_server.c
index 05d382b..1adfe3e 100644
--- a/library/ssl_tls12_server.c
+++ b/library/ssl_tls12_server.c
@@ -4112,10 +4112,6 @@
         psa_status_t destruction_status = PSA_ERROR_CORRUPTION_DETECTED;
         uint8_t ecpoint_len;
 
-        /* Opaque PSKs are currently only supported for PSK-only. */
-        if( ssl_use_opaque_psk( ssl ) == 1 )
-            return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
-
         mbedtls_ssl_handshake_params *handshake = ssl->handshake;
 
         if( ( ret = ssl_parse_client_psk_identity( ssl, &p, end ) ) != 0 )
@@ -4188,28 +4184,38 @@
         const unsigned char *psk = NULL;
         size_t psk_len = 0;
 
-        if( mbedtls_ssl_get_psk( ssl, &psk, &psk_len )
-                == MBEDTLS_ERR_SSL_PRIVATE_KEY_REQUIRED )
-            /*
-             * This should never happen because the existence of a PSK is always
-             * checked before calling this function
-             */
-            return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
+        /* In case of opaque psk skip writting psk to pms.
+         * Opaque key will be handled later. */
+        if( ssl_use_opaque_psk( ssl ) == 0 )
+        {
+            if( mbedtls_ssl_get_psk( ssl, &psk, &psk_len )
+                    == MBEDTLS_ERR_SSL_PRIVATE_KEY_REQUIRED )
+                /*
+                * This should never happen because the existence of a PSK is always
+                * checked before calling this function
+                */
+                return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
 
-        /* opaque psk<0..2^16-1>; */
-        if( (size_t)( psm_end - psm ) < ( 2 + psk_len ) )
-            return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
+            /* opaque psk<0..2^16-1>; */
+            if( (size_t)( psm_end - psm ) < ( 2 + psk_len ) )
+                return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
 
-        /* Write the PSK length as uint16 */
-        MBEDTLS_PUT_UINT16_BE( psk_len, psm, 0 );
-        psm += 2;
+            /* Write the PSK length as uint16 */
+            MBEDTLS_PUT_UINT16_BE( psk_len, psm, 0 );
+            psm += 2;
 
-        /* Write the PSK itself */
-        memcpy( psm, psk, psk_len );
-        psm += psk_len;
+            /* Write the PSK itself */
+            memcpy( psm, psk, psk_len );
+            psm += psk_len;
 
-        ssl->handshake->pmslen = psm - ssl->handshake->premaster;
-#else
+            ssl->handshake->pmslen = psm - ssl->handshake->premaster;
+        }
+        else
+        {
+            MBEDTLS_SSL_DEBUG_MSG( 1,
+                ( "skip PMS generation for opaque ECDHE-PSK" ) );
+        }
+#else /* MBEDTLS_USE_PSA_CRYPTO */
         if( ( ret = ssl_parse_client_psk_identity( ssl, &p, end ) ) != 0 )
         {
             MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_parse_client_psk_identity" ), ret );