Merge branch 'mbedtls-3.6-restricted' into mbedtls-3.6.3rc0-pr

Signed-off-by: Minos Galanakis <minos.galanakis@arm.com>

ChangeLog.d/mbedtls_ssl_set_hostname.txt

@@ -0,0 +1,18 @@
+Default behavior changes
+   * In TLS clients, if mbedtls_ssl_set_hostname() has not been called,
+     mbedtls_ssl_handshake() now fails with
+     MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+     if certificate-based authentication of the server is attempted.
+     This is because authenticating a server without knowing what name
+     to expect is usually insecure. To restore the old behavior, either
+     call mbedtls_ssl_set_hostname() with NULL as the hostname, or
+     enable the new compile-time option
+     MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME.
+
+Security
+   * Note that TLS clients should generally call mbedtls_ssl_set_hostname()
+     if they use certificate authentication (i.e. not pre-shared keys).
+     Otherwise, in many scenarios, the server could be impersonated.
+     The library will now prevent the handshake and return
+     MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+     if mbedtls_ssl_set_hostname() has not been called.

ChangeLog.d/psa-zeroize.txt

@@ -0,0 +1,4 @@
+Security
+   * Zeroize a temporary heap buffer used in psa_key_derivation_output_key()
+     when deriving an ECC key pair.
+   * Zeroize temporary heap buffers used in PSA operations.

ChangeLog.d/tls12-check-finished-calc.txt

@@ -0,0 +1,6 @@
+Security
+   * Fix a vulnerability in the TLS 1.2 handshake. If memory allocation failed
+     or there was a cryptographic hardware failure when calculating the
+     Finished message, it could be calculated incorrectly. This would break
+     the security guarantees of the TLS handshake.
+     CVE-2025-27810

include/mbedtls/error.h

@@ -81,7 +81,7 @@
  * MD        5   5
  * HKDF      5   1 (Started from top)
  * PKCS7     5   12 (Started from 0x5300)
- * SSL       5   2 (Started from 0x5F00)
+ * SSL       5   3 (Started from 0x5F00)
  * CIPHER    6   8 (Started from 0x6080)
  * SSL       6   22 (Started from top, plus 0x6000)
  * SSL       7   20 (Started from 0x7000, gaps at

include/mbedtls/mbedtls_config.h

@@ -1622,6 +1622,46 @@
  */
 //#define MBEDTLS_SSL_ASYNC_PRIVATE
 
+/** \def MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+ *
+ * In TLS clients, when a client authenticates a server through its
+ * certificate, the client normally checks three things:
+ * - the certificate chain must be valid;
+ * - the chain must start from a trusted CA;
+ * - the certificate must cover the server name that is expected by the client.
+ *
+ * Omitting any of these checks is generally insecure, and can allow a
+ * malicious server to impersonate a legitimate server.
+ *
+ * The third check may be safely skipped in some unusual scenarios,
+ * such as networks where eavesdropping is a risk but not active attacks,
+ * or a private PKI where the client equally trusts all servers that are
+ * accredited by the root CA.
+ *
+ * You should call mbedtls_ssl_set_hostname() with the expected server name
+ * before starting a TLS handshake on a client (unless the client is
+ * set up to only use PSK-based authentication, which does not rely on the
+ * host name). This configuration option controls what happens if a TLS client
+ * is configured with the authentication mode #MBEDTLS_SSL_VERIFY_REQUIRED
+ * (default), certificate authentication is enabled and the client does not
+ * call mbedtls_ssl_set_hostname():
+ *
+ * - If this option is unset (default), the connection attempt is aborted
+ *   with the error #MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME.
+ * - If this option is set, the TLS library does not check the server name
+ *   that the certificate is valid for. This is the historical behavior
+ *   of Mbed TLS, but may be insecure as explained above.
+ *
+ * Enable this option for strict backward compatibility if you have
+ * determined that it is secure in the scenario where you are using
+ * Mbed TLS.
+ *
+ * \deprecated This option exists only for backward compatibility and will
+ *             be removed in the next major version of Mbed TLS.
+ *
+ */
+//#define MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+
 /**
  * \def MBEDTLS_SSL_CONTEXT_SERIALIZATION
  *

include/mbedtls/ssl.h

@@ -166,6 +166,42 @@
 #define MBEDTLS_ERR_SSL_VERSION_MISMATCH                  -0x5F00
 /** Invalid value in SSL config */
 #define MBEDTLS_ERR_SSL_BAD_CONFIG                        -0x5E80
+/* Error space gap */
+/** Attempt to verify a certificate without an expected hostname.
+ * This is usually insecure.
+ *
+ * In TLS clients, when a client authenticates a server through its
+ * certificate, the client normally checks three things:
+ * - the certificate chain must be valid;
+ * - the chain must start from a trusted CA;
+ * - the certificate must cover the server name that is expected by the client.
+ *
+ * Omitting any of these checks is generally insecure, and can allow a
+ * malicious server to impersonate a legitimate server.
+ *
+ * The third check may be safely skipped in some unusual scenarios,
+ * such as networks where eavesdropping is a risk but not active attacks,
+ * or a private PKI where the client equally trusts all servers that are
+ * accredited by the root CA.
+ *
+ * You should call mbedtls_ssl_set_hostname() with the expected server name
+ * before starting a TLS handshake on a client (unless the client is
+ * set up to only use PSK-based authentication, which does not rely on the
+ * host name). If you have determined that server name verification is not
+ * required for security in your scenario, call mbedtls_ssl_set_hostname()
+ * with \p NULL as the server name.
+ *
+ * This error is raised if all of the following conditions are met:
+ *
+ * - A TLS client is configured with the authentication mode
+ *   #MBEDTLS_SSL_VERIFY_REQUIRED (default).
+ * - Certificate authentication is enabled.
+ * - The client does not call mbedtls_ssl_set_hostname().
+ * - The configuration option
+ *   #MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+ *   is not enabled.
+ */
+#define MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME  -0x5D80
 
 /*
  * Constants from RFC 8446 for TLS 1.3 PSK modes
@@ -1893,8 +1929,35 @@ struct mbedtls_ssl_context {
      * User settings
      */
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
-    char *MBEDTLS_PRIVATE(hostname);             /*!< expected peer CN for verification
+    /** Expected peer CN for verification.
-                                                    (and SNI if available)                 */
+     *
+     * Also used on clients for SNI,
+     * and for TLS 1.3 session resumption using tickets.
+     *
+     * The value of this field can be:
+     * - \p NULL in a newly initialized or reset context.
+     * - A heap-allocated copy of the last value passed to
+     *   mbedtls_ssl_set_hostname(), if the last call had a non-null
+     *  \p hostname argument.
+     * - A special value to indicate that mbedtls_ssl_set_hostname()
+     *   was called with \p NULL (as opposed to never having been called).
+     *   See `mbedtls_ssl_get_hostname_pointer()` in `ssl_tls.c`.
+     *
+     * If this field contains the value \p NULL and the configuration option
+     * #MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+     * is unset, on a TLS client, attempting to verify a server certificate
+     * results in the error
+     * #MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME.
+     *
+     * If this field contains the special value described above, or if
+     * the value is \p NULL and the configuration option
+     * #MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+     * is set, then the peer name verification is skipped, which may be
+     * insecure, especially on a client. Furthermore, on a client, the
+     * server_name extension is not sent, and the server name is ignored
+     * in TLS 1.3 session resumption using tickets.
+     */
+    char *MBEDTLS_PRIVATE(hostname);
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
 #if defined(MBEDTLS_SSL_ALPN)
@@ -2002,6 +2065,14 @@ void mbedtls_ssl_init(mbedtls_ssl_context *ssl);
  *                 Calling mbedtls_ssl_setup again is not supported, even
  *                 if no session is active.
  *
+ * \warning        After setting up a client context, if certificate-based
+ *                 authentication is enabled, you should call
+ *                 mbedtls_ssl_set_hostname() to specifiy the expected
+ *                 name of the server. Without this, in most scenarios,
+ *                 the TLS connection is insecure. See
+ *                 #MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+ *                 for more information.
+ *
  * \note           If #MBEDTLS_USE_PSA_CRYPTO is enabled, the PSA crypto
  *                 subsystem must have been initialized by calling
  *                 psa_crypto_init() before calling this function.
@@ -3976,16 +4047,29 @@ void mbedtls_ssl_conf_sig_algs(mbedtls_ssl_config *conf,
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
 /**
  * \brief          Set or reset the hostname to check against the received
- *                 server certificate. It sets the ServerName TLS extension,
+ *                 peer certificate. On a client, this also sets the
- *                 too, if that extension is enabled. (client-side only)
+ *                 ServerName TLS extension, if that extension is enabled.
+ *                 On a TLS 1.3 client, this also sets the server name in
+ *                 the session resumption ticket, if that feature is enabled.
  *
  * \param ssl      SSL context
- * \param hostname the server hostname, may be NULL to clear hostname
+ * \param hostname The server hostname. This may be \c NULL to clear
-
+ *                 the hostname.
- * \note           Maximum hostname length MBEDTLS_SSL_MAX_HOST_NAME_LEN.
  *
- * \return         0 if successful, MBEDTLS_ERR_SSL_ALLOC_FAILED on
+ * \note           Maximum hostname length #MBEDTLS_SSL_MAX_HOST_NAME_LEN.
- *                 allocation failure, MBEDTLS_ERR_SSL_BAD_INPUT_DATA on
+ *
+ * \note           If the hostname is \c NULL on a client, then the server
+ *                 is not authenticated: it only needs to have a valid
+ *                 certificate, not a certificate matching its name.
+ *                 Therefore you should always call this function on a client,
+ *                 unless the connection is set up to only allow
+ *                 pre-shared keys, or in scenarios where server
+ *                 impersonation is not a concern. See the documentation of
+ *                 #MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+ *                 for more details.
+ *
+ * \return         0 if successful, #MBEDTLS_ERR_SSL_ALLOC_FAILED on
+ *                 allocation failure, #MBEDTLS_ERR_SSL_BAD_INPUT_DATA on
  *                 too long input hostname.
  *
  *                 Hostname set to the one provided on success (cleared

library/psa_crypto.c

@@ -6316,7 +6316,7 @@ static psa_status_t psa_generate_derived_ecc_key_weierstrass_helper(
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
     size_t m;
-    size_t m_bytes;
+    size_t m_bytes = 0;
 
     mbedtls_mpi_init(&k);
     mbedtls_mpi_init(&diff_N_2);
@@ -6389,7 +6389,7 @@ cleanup:
         status = mbedtls_to_psa_error(ret);
     }
     if (status != PSA_SUCCESS) {
-        mbedtls_free(*data);
+        mbedtls_zeroize_and_free(*data, m_bytes);
         *data = NULL;
     }
     mbedtls_mpi_free(&k);
@@ -6564,7 +6564,7 @@ static psa_status_t psa_generate_derived_key_internal(
     }
 
 exit:
-    mbedtls_free(data);
+    mbedtls_zeroize_and_free(data, bytes);
     return status;
 }
 
@@ -9313,7 +9313,7 @@ psa_status_t psa_crypto_local_input_alloc(const uint8_t *input, size_t input_len
     return PSA_SUCCESS;
 
 error:
-    mbedtls_free(local_input->buffer);
+    mbedtls_zeroize_and_free(local_input->buffer, local_input->length);
     local_input->buffer = NULL;
     local_input->length = 0;
     return status;
@@ -9321,7 +9321,7 @@ error:
 
 void psa_crypto_local_input_free(psa_crypto_local_input_t *local_input)
 {
-    mbedtls_free(local_input->buffer);
+    mbedtls_zeroize_and_free(local_input->buffer, local_input->length);
     local_input->buffer = NULL;
     local_input->length = 0;
 }
@@ -9365,7 +9365,7 @@ psa_status_t psa_crypto_local_output_free(psa_crypto_local_output_t *local_outpu
         return status;
     }
 
-    mbedtls_free(local_output->buffer);
+    mbedtls_zeroize_and_free(local_output->buffer, local_output->length);
     local_output->buffer = NULL;
     local_output->length = 0;
 

library/ssl_client.c

@@ -29,19 +29,20 @@ static int ssl_write_hostname_ext(mbedtls_ssl_context *ssl,
                                   size_t *olen)
 {
     unsigned char *p = buf;
+    const char *hostname = mbedtls_ssl_get_hostname_pointer(ssl);
     size_t hostname_len;
 
     *olen = 0;
 
-    if (ssl->hostname == NULL) {
+    if (hostname == NULL) {
         return 0;
     }
 
     MBEDTLS_SSL_DEBUG_MSG(3,
                           ("client hello, adding server name extension: %s",
-                           ssl->hostname));
+                           hostname));
 
-    hostname_len = strlen(ssl->hostname);
+    hostname_len = strlen(hostname);
 
     MBEDTLS_SSL_CHK_BUF_PTR(p, end, hostname_len + 9);
 
@@ -85,7 +86,7 @@ static int ssl_write_hostname_ext(mbedtls_ssl_context *ssl,
     MBEDTLS_PUT_UINT16_BE(hostname_len, p, 0);
     p += 2;
 
-    memcpy(p, ssl->hostname, hostname_len);
+    memcpy(p, hostname, hostname_len);
 
     *olen = hostname_len + 9;
 
@@ -881,13 +882,14 @@ static int ssl_prepare_client_hello(mbedtls_ssl_context *ssl)
 #if defined(MBEDTLS_SSL_PROTO_TLS1_3) && \
     defined(MBEDTLS_SSL_SESSION_TICKETS) && \
     defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+    const char *context_hostname = mbedtls_ssl_get_hostname_pointer(ssl);
     if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3  &&
         ssl->handshake->resume) {
-        int hostname_mismatch = ssl->hostname != NULL ||
+        int hostname_mismatch = context_hostname != NULL ||
                                 session_negotiate->hostname != NULL;
-        if (ssl->hostname != NULL && session_negotiate->hostname != NULL) {
+        if (context_hostname != NULL && session_negotiate->hostname != NULL) {
             hostname_mismatch = strcmp(
-                ssl->hostname, session_negotiate->hostname) != 0;
+                context_hostname, session_negotiate->hostname) != 0;
         }
 
         if (hostname_mismatch) {
@@ -898,7 +900,7 @@ static int ssl_prepare_client_hello(mbedtls_ssl_context *ssl)
         }
     } else {
         return mbedtls_ssl_session_set_hostname(session_negotiate,
-                                                ssl->hostname);
+                                                context_hostname);
     }
 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 &&
           MBEDTLS_SSL_SESSION_TICKETS &&

library/ssl_misc.h

@@ -2900,6 +2900,18 @@ int mbedtls_ssl_tls13_write_binders_of_pre_shared_key_ext(
     unsigned char *buf, unsigned char *end);
 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */
 
+#if defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+/** Get the host name from the SSL context.
+ *
+ * \param[in]   ssl     SSL context
+ *
+ * \return The \p hostname pointer from the SSL context.
+ *         \c NULL if mbedtls_ssl_set_hostname() has never been called on
+ *         \p ssl or if it was last called with \p NULL.
+ */
+const char *mbedtls_ssl_get_hostname_pointer(const mbedtls_ssl_context *ssl);
+#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
+
 #if defined(MBEDTLS_SSL_PROTO_TLS1_3) && \
     defined(MBEDTLS_SSL_SESSION_TICKETS) && \
     defined(MBEDTLS_SSL_SERVER_NAME_INDICATION) && \

library/ssl_tls.c

@@ -2769,6 +2769,51 @@ void mbedtls_ssl_conf_groups(mbedtls_ssl_config *conf,
 }
 
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
+
+/* A magic value for `ssl->hostname` indicating that
+ * mbedtls_ssl_set_hostname() has been called with `NULL`.
+ * If mbedtls_ssl_set_hostname() has never been called on `ssl`, then
+ * `ssl->hostname == NULL`. */
+static const char *const ssl_hostname_skip_cn_verification = "";
+
+#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
+/** Whether mbedtls_ssl_set_hostname() has been called.
+ *
+ * \param[in]   ssl     SSL context
+ *
+ * \return \c 1 if mbedtls_ssl_set_hostname() has been called on \p ssl
+ *         (including `mbedtls_ssl_set_hostname(ssl, NULL)`),
+ *         otherwise \c 0.
+ */
+static int mbedtls_ssl_has_set_hostname_been_called(
+    const mbedtls_ssl_context *ssl)
+{
+    return ssl->hostname != NULL;
+}
+#endif
+
+/* Micro-optimization: don't export this function if it isn't needed outside
+ * of this source file. */
+#if !defined(MBEDTLS_SSL_SERVER_NAME_INDICATION)
+static
+#endif
+const char *mbedtls_ssl_get_hostname_pointer(const mbedtls_ssl_context *ssl)
+{
+    if (ssl->hostname == ssl_hostname_skip_cn_verification) {
+        return NULL;
+    }
+    return ssl->hostname;
+}
+
+static void mbedtls_ssl_free_hostname(mbedtls_ssl_context *ssl)
+{
+    if (ssl->hostname != NULL &&
+        ssl->hostname != ssl_hostname_skip_cn_verification) {
+        mbedtls_zeroize_and_free(ssl->hostname, strlen(ssl->hostname));
+    }
+    ssl->hostname = NULL;
+}
+
 int mbedtls_ssl_set_hostname(mbedtls_ssl_context *ssl, const char *hostname)
 {
     /* Initialize to suppress unnecessary compiler warning */
@@ -2786,18 +2831,21 @@ int mbedtls_ssl_set_hostname(mbedtls_ssl_context *ssl, const char *hostname)
 
     /* Now it's clear that we will overwrite the old hostname,
      * so we can free it safely */
-
+    mbedtls_ssl_free_hostname(ssl);
-    if (ssl->hostname != NULL) {
-        mbedtls_zeroize_and_free(ssl->hostname, strlen(ssl->hostname));
-    }
-
-    /* Passing NULL as hostname shall clear the old one */
 
     if (hostname == NULL) {
-        ssl->hostname = NULL;
+        /* Passing NULL as hostname clears the old one, but leaves a
+         * special marker to indicate that mbedtls_ssl_set_hostname()
+         * has been called. */
+        /* ssl->hostname should be const, but isn't. We won't actually
+         * write to the buffer, so it's ok to cast away the const. */
+        ssl->hostname = (char *) ssl_hostname_skip_cn_verification;
     } else {
         ssl->hostname = mbedtls_calloc(1, hostname_len + 1);
         if (ssl->hostname == NULL) {
+            /* mbedtls_ssl_set_hostname() has been called, but unsuccessfully.
+             * Leave ssl->hostname in the same state as if the function had
+             * not been called, i.e. a null pointer. */
             return MBEDTLS_ERR_SSL_ALLOC_FAILED;
         }
 
@@ -5583,9 +5631,7 @@ void mbedtls_ssl_free(mbedtls_ssl_context *ssl)
     }
 
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
-    if (ssl->hostname != NULL) {
+    mbedtls_ssl_free_hostname(ssl);
-        mbedtls_zeroize_and_free(ssl->hostname, strlen(ssl->hostname));
-    }
 #endif
 
 #if defined(MBEDTLS_SSL_DTLS_HELLO_VERIFY) && defined(MBEDTLS_SSL_SRV_C)
@@ -8323,6 +8369,7 @@ int mbedtls_ssl_write_finished(mbedtls_ssl_context *ssl)
     ret = ssl->handshake->calc_finished(ssl, ssl->out_msg + 4, ssl->conf->endpoint);
     if (ret != 0) {
         MBEDTLS_SSL_DEBUG_RET(1, "calc_finished", ret);
+        return ret;
     }
 
     /*
@@ -8436,6 +8483,7 @@ int mbedtls_ssl_parse_finished(mbedtls_ssl_context *ssl)
     ret = ssl->handshake->calc_finished(ssl, buf, ssl->conf->endpoint ^ 1);
     if (ret != 0) {
         MBEDTLS_SSL_DEBUG_RET(1, "calc_finished", ret);
+        return ret;
     }
 
     if ((ret = mbedtls_ssl_read_record(ssl, 1)) != 0) {
@@ -9796,6 +9844,27 @@ int mbedtls_ssl_check_cert_usage(const mbedtls_x509_crt *cert,
     return ret;
 }
 
+static int get_hostname_for_verification(mbedtls_ssl_context *ssl,
+                                         const char **hostname)
+{
+    if (!mbedtls_ssl_has_set_hostname_been_called(ssl)) {
+        MBEDTLS_SSL_DEBUG_MSG(1, ("Certificate verification without having set hostname"));
+#if !defined(MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME)
+        if (mbedtls_ssl_conf_get_endpoint(ssl->conf) == MBEDTLS_SSL_IS_CLIENT &&
+            ssl->conf->authmode == MBEDTLS_SSL_VERIFY_REQUIRED) {
+            return MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME;
+        }
+#endif
+    }
+
+    *hostname = mbedtls_ssl_get_hostname_pointer(ssl);
+    if (*hostname == NULL) {
+        MBEDTLS_SSL_DEBUG_MSG(2, ("Certificate verification without CN verification"));
+    }
+
+    return 0;
+}
+
 int mbedtls_ssl_verify_certificate(mbedtls_ssl_context *ssl,
                                    int authmode,
                                    mbedtls_x509_crt *chain,
@@ -9821,7 +9890,13 @@ int mbedtls_ssl_verify_certificate(mbedtls_ssl_context *ssl,
         p_vrfy = ssl->conf->p_vrfy;
     }
 
-    int ret = 0;
+    const char *hostname = "";
+    int ret = get_hostname_for_verification(ssl, &hostname);
+    if (ret != 0) {
+        MBEDTLS_SSL_DEBUG_RET(1, "get_hostname_for_verification", ret);
+        return ret;
+    }
+
     int have_ca_chain_or_callback = 0;
 #if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
     if (ssl->conf->f_ca_cb != NULL) {
@@ -9834,7 +9909,7 @@ int mbedtls_ssl_verify_certificate(mbedtls_ssl_context *ssl,
             ssl->conf->f_ca_cb,
             ssl->conf->p_ca_cb,
             ssl->conf->cert_profile,
-            ssl->hostname,
+            hostname,
             &ssl->session_negotiate->verify_result,
             f_vrfy, p_vrfy);
     } else
@@ -9861,7 +9936,7 @@ int mbedtls_ssl_verify_certificate(mbedtls_ssl_context *ssl,
             chain,
             ca_chain, ca_crl,
             ssl->conf->cert_profile,
-            ssl->hostname,
+            hostname,
             &ssl->session_negotiate->verify_result,
             f_vrfy, p_vrfy, rs_ctx);
     }

programs/ssl/ssl_client2.c

@@ -68,6 +68,7 @@ int main(void)
 #define DFL_MAX_VERSION         -1
 #define DFL_SHA1                -1
 #define DFL_AUTH_MODE           -1
+#define DFL_SET_HOSTNAME        1
 #define DFL_MFL_CODE            MBEDTLS_SSL_MAX_FRAG_LEN_NONE
 #define DFL_TRUNC_HMAC          -1
 #define DFL_RECSPLIT            -1
@@ -407,6 +408,9 @@ int main(void)
 #define USAGE2 \
     "    auth_mode=%%s        default: (library default: none)\n" \
     "                        options: none, optional, required\n" \
+    "    set_hostname=%%s     call mbedtls_ssl_set_hostname()?" \
+    "                        options: no, server_name, NULL\n" \
+    "                        default: server_name (but ignored if certs disabled)\n"  \
     USAGE_IO                                                \
     USAGE_KEY_OPAQUE                                        \
     USAGE_CA_CALLBACK                                       \
@@ -509,6 +513,8 @@ struct options {
     int max_version;            /* maximum protocol version accepted        */
     int allow_sha1;             /* flag for SHA-1 support                   */
     int auth_mode;              /* verify mode for connection               */
+    int set_hostname;           /* call mbedtls_ssl_set_hostname()?         */
+                                /* 0=no, 1=yes, -1=NULL */
     unsigned char mfl_code;     /* code for maximum fragment length         */
     int trunc_hmac;             /* negotiate truncated hmac or not          */
     int recsplit;               /* enable record splitting?                 */
@@ -965,6 +971,7 @@ int main(int argc, char *argv[])
     opt.max_version         = DFL_MAX_VERSION;
     opt.allow_sha1          = DFL_SHA1;
     opt.auth_mode           = DFL_AUTH_MODE;
+    opt.set_hostname        = DFL_SET_HOSTNAME;
     opt.mfl_code            = DFL_MFL_CODE;
     opt.trunc_hmac          = DFL_TRUNC_HMAC;
     opt.recsplit            = DFL_RECSPLIT;
@@ -1364,6 +1371,16 @@ usage:
             } else {
                 goto usage;
             }
+        } else if (strcmp(p, "set_hostname") == 0) {
+            if (strcmp(q, "no") == 0) {
+                opt.set_hostname = 0;
+            } else if (strcmp(q, "server_name") == 0) {
+                opt.set_hostname = 1;
+            } else if (strcmp(q, "NULL") == 0) {
+                opt.set_hostname = -1;
+            } else {
+                goto usage;
+            }
         } else if (strcmp(p, "max_frag_len") == 0) {
             if (strcmp(q, "512") == 0) {
                 opt.mfl_code = MBEDTLS_SSL_MAX_FRAG_LEN_512;
@@ -2081,10 +2098,24 @@ usage:
 #endif /* MBEDTLS_SSL_DTLS_SRTP */
 
 #if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
-    if ((ret = mbedtls_ssl_set_hostname(&ssl, opt.server_name)) != 0) {
+    switch (opt.set_hostname) {
-        mbedtls_printf(" failed\n  ! mbedtls_ssl_set_hostname returned %d\n\n",
+        case -1:
-                       ret);
+            if ((ret = mbedtls_ssl_set_hostname(&ssl, NULL)) != 0) {
-        goto exit;
+                mbedtls_printf(" failed\n  ! mbedtls_ssl_set_hostname returned %d\n\n",
+                               ret);
+                goto exit;
+            }
+            break;
+        case 0:
+            /* Skip the call */
+            break;
+        default:
+            if ((ret = mbedtls_ssl_set_hostname(&ssl, opt.server_name)) != 0) {
+                mbedtls_printf(" failed\n  ! mbedtls_ssl_set_hostname returned %d\n\n",
+                               ret);
+                goto exit;
+            }
+            break;
     }
 #endif
 

programs/ssl/ssl_test_common_source.c

@@ -315,7 +315,7 @@ uint16_t ssl_sig_algs_for_test[] = {
 };
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
-#if defined(MBEDTLS_X509_CRT_PARSE_C)
+#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
 /** Functionally equivalent to mbedtls_x509_crt_verify_info, see that function
  *  for more info.
  */
@@ -350,9 +350,7 @@ static int x509_crt_verify_info(char *buf, size_t size, const char *prefix,
     return (int) (size - n);
 #endif /* MBEDTLS_X509_REMOVE_INFO */
 }
-#endif /* MBEDTLS_X509_CRT_PARSE_C */
 
-#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
 static void mbedtls_print_supported_sig_algs(void)
 {
     mbedtls_printf("supported signature algorithms:\n");

scripts/config.py

@@ -229,6 +229,7 @@ def crypto_adapter(adapter):
 
 DEPRECATED = frozenset([
     'MBEDTLS_PSA_CRYPTO_SE_C',
+    'MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME',
 ])
 def no_deprecated_adapter(adapter):
     """Modify an adapter to disable deprecated symbols.

tests/scripts/components-configuration.sh

@@ -175,6 +175,9 @@ component_test_full_no_deprecated () {
 
     msg "test: ensure that X509 has no direct dependency on BIGNUM_C"
     not grep mbedtls_mpi library/libmbedx509.a
+
+    msg "test: ssl-opt.sh authentication, full_no_deprecated config" # ~ 10s
+    tests/ssl-opt.sh -f 'Default\|Authentication'
 }
 
 component_test_full_no_deprecated_deprecated_warning () {

tests/src/test_helpers/ssl_helpers.c

@@ -868,6 +868,10 @@ int mbedtls_test_ssl_endpoint_init(
     ret = mbedtls_ssl_setup(&(ep->ssl), &(ep->conf));
     TEST_ASSERT(ret == 0);
 
+    if (MBEDTLS_SSL_IS_CLIENT == endpoint_type) {
+        ret = mbedtls_ssl_set_hostname(&(ep->ssl), "localhost");
+    }
+
 #if defined(MBEDTLS_SSL_PROTO_DTLS) && defined(MBEDTLS_SSL_SRV_C)
     if (endpoint_type == MBEDTLS_SSL_IS_SERVER && dtls_context != NULL) {
         mbedtls_ssl_conf_dtls_cookies(&(ep->conf), NULL, NULL, NULL);

tests/ssl-opt.sh

@@ -492,6 +492,11 @@ detect_required_features() {
             requires_certificate_authentication;;
     esac
 
+    case " $CMD_LINE " in
+        *\ ca_callback=1\ *)
+            requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK;;
+    esac
+
     case " $CMD_LINE " in
         *"programs/ssl/dtls_client "*|\
         *"programs/ssl/ssl_client1 "*)
@@ -2256,7 +2261,6 @@ run_test    "TLS: password protected server key, two certificates" \
             "$P_CLI" \
             0
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "CA callback on client" \
             "$P_SRV debug_level=3" \
             "$P_CLI ca_callback=1 debug_level=3 " \
@@ -2265,7 +2269,6 @@ run_test    "CA callback on client" \
             -S "error" \
             -C "error"
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 requires_config_enabled MBEDTLS_X509_CRT_PARSE_C
 requires_hash_alg SHA_256
 run_test    "CA callback on server" \
@@ -6074,6 +6077,271 @@ run_test    "Authentication: server goodcert, client none, no trusted CA (1.2)"
             -C "X509 - Certificate verification failed" \
             -C "SSL - No CA Chain is set, but required to operate"
 
+# The next few tests check what happens if the server has a valid certificate
+# that does not match its name (impersonation).
+
+run_test "Authentication: hostname match, client required" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required server_name=localhost debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -C "Certificate verification without having set hostname" \
+         -C "Certificate verification without CN verification" \
+         -C "x509_verify_cert() returned -" \
+         -C "! mbedtls_ssl_handshake returned" \
+         -C "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname match, client required, CA callback" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required server_name=localhost debug_level=3 ca_callback=1" \
+         0 \
+         -C "does not match with the expected CN" \
+         -C "Certificate verification without having set hostname" \
+         -C "Certificate verification without CN verification" \
+         -c "use CA callback for X.509 CRT verification" \
+         -C "x509_verify_cert() returned -" \
+         -C "! mbedtls_ssl_handshake returned" \
+         -C "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname mismatch (wrong), client required" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required server_name=wrong-name debug_level=1" \
+         1 \
+         -c "does not match with the expected CN" \
+         -c "x509_verify_cert() returned -" \
+         -c "! mbedtls_ssl_handshake returned" \
+         -c "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname mismatch (empty), client required" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required server_name= debug_level=1" \
+         1 \
+         -c "does not match with the expected CN" \
+         -c "x509_verify_cert() returned -" \
+         -c "! mbedtls_ssl_handshake returned" \
+         -c "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname mismatch (truncated), client required" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required server_name=localhos debug_level=1" \
+         1 \
+         -c "does not match with the expected CN" \
+         -c "x509_verify_cert() returned -" \
+         -c "! mbedtls_ssl_handshake returned" \
+         -c "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname mismatch (last char), client required" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required server_name=localhoss debug_level=1" \
+         1 \
+         -c "does not match with the expected CN" \
+         -c "x509_verify_cert() returned -" \
+         -c "! mbedtls_ssl_handshake returned" \
+         -c "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname mismatch (trailing), client required" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required server_name=localhostt debug_level=1" \
+         1 \
+         -c "does not match with the expected CN" \
+         -c "x509_verify_cert() returned -" \
+         -c "! mbedtls_ssl_handshake returned" \
+         -c "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname mismatch, client optional" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=optional server_name=wrong-name debug_level=2" \
+         0 \
+         -c "does not match with the expected CN" \
+         -c "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname mismatch, client none" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=none server_name=wrong-name debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -C "Certificate verification without having set hostname" \
+         -C "Certificate verification without CN verification" \
+         -C "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname null, client required" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required set_hostname=NULL debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -C "Certificate verification without having set hostname" \
+         -c "Certificate verification without CN verification" \
+         -C "x509_verify_cert() returned -" \
+         -C "! mbedtls_ssl_handshake returned" \
+         -C "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname null, client optional" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=optional set_hostname=NULL debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -C "Certificate verification without having set hostname" \
+         -c "Certificate verification without CN verification" \
+         -C "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname null, client none" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=none set_hostname=NULL debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -C "Certificate verification without having set hostname" \
+         -C "Certificate verification without CN verification" \
+         -C "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
+requires_config_disabled MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+run_test "Authentication: hostname unset, client required, secure config" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required set_hostname=no debug_level=2" \
+         1 \
+         -C "does not match with the expected CN" \
+         -c "Certificate verification without having set hostname" \
+         -C "Certificate verification without CN verification" \
+         -c "get_hostname_for_verification() returned -" \
+         -C "x509_verify_cert() returned -" \
+         -c "! mbedtls_ssl_handshake returned" \
+         -C "X509 - Certificate verification failed"
+
+requires_config_enabled MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+run_test "Authentication: hostname unset, client required, historical config" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required set_hostname=no debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -c "Certificate verification without having set hostname" \
+         -c "Certificate verification without CN verification" \
+         -C "get_hostname_for_verification() returned -" \
+         -C "x509_verify_cert() returned -" \
+         -C "! mbedtls_ssl_handshake returned" \
+         -C "X509 - Certificate verification failed"
+
+requires_config_disabled MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+run_test "Authentication: hostname unset, client required, secure config, CA callback" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required set_hostname=no debug_level=3 ca_callback=1" \
+         1 \
+         -C "does not match with the expected CN" \
+         -c "Certificate verification without having set hostname" \
+         -C "Certificate verification without CN verification" \
+         -c "get_hostname_for_verification() returned -" \
+         -C "use CA callback for X.509 CRT verification" \
+         -C "x509_verify_cert() returned -" \
+         -c "! mbedtls_ssl_handshake returned" \
+         -C "X509 - Certificate verification failed"
+
+requires_config_enabled MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+run_test "Authentication: hostname unset, client required, historical config, CA callback" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=required set_hostname=no debug_level=3 ca_callback=1" \
+         0 \
+         -C "does not match with the expected CN" \
+         -c "Certificate verification without having set hostname" \
+         -c "Certificate verification without CN verification" \
+         -C "get_hostname_for_verification() returned -" \
+         -c "use CA callback for X.509 CRT verification" \
+         -C "x509_verify_cert() returned -" \
+         -C "! mbedtls_ssl_handshake returned" \
+         -C "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname unset, client optional" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=optional set_hostname=no debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -c "Certificate verification without having set hostname" \
+         -c "Certificate verification without CN verification" \
+         -C "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname unset, client none" \
+         "$P_SRV" \
+         "$P_CLI auth_mode=none set_hostname=no debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -C "Certificate verification without having set hostname" \
+         -C "Certificate verification without CN verification" \
+         -C "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
+requires_config_disabled MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+run_test "Authentication: hostname unset, client default, secure config, server picks cert, 1.2" \
+         "$P_SRV force_version=tls12 force_ciphersuite=TLS-ECDHE-ECDSA-WITH-AES-128-CCM-8" \
+         "$P_CLI psk=73776f726466697368 psk_identity=foo set_hostname=no debug_level=2" \
+         1 \
+         -C "does not match with the expected CN" \
+         -c "Certificate verification without having set hostname" \
+         -C "Certificate verification without CN verification" \
+         -c "get_hostname_for_verification() returned -" \
+         -C "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
+requires_config_disabled MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+requires_config_enabled MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED
+run_test "Authentication: hostname unset, client default, secure config, server picks cert, 1.3" \
+         "$P_SRV force_version=tls13 tls13_kex_modes=ephemeral" \
+         "$P_CLI psk=73776f726466697368 psk_identity=foo set_hostname=no debug_level=2" \
+         1 \
+         -C "does not match with the expected CN" \
+         -c "Certificate verification without having set hostname" \
+         -C "Certificate verification without CN verification" \
+         -c "get_hostname_for_verification() returned -" \
+         -C "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
+requires_config_enabled MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+run_test "Authentication: hostname unset, client default, historical config, server picks cert, 1.2" \
+         "$P_SRV force_version=tls12 force_ciphersuite=TLS-ECDHE-ECDSA-WITH-AES-128-CCM-8" \
+         "$P_CLI psk=73776f726466697368 psk_identity=foo set_hostname=no debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -c "Certificate verification without having set hostname" \
+         -c "Certificate verification without CN verification" \
+         -C "get_hostname_for_verification() returned -" \
+         -C "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
+requires_config_enabled MBEDTLS_SSL_CLI_ALLOW_WEAK_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
+requires_config_enabled MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED
+run_test "Authentication: hostname unset, client default, historical config, server picks cert, 1.3" \
+         "$P_SRV force_version=tls13 tls13_kex_modes=ephemeral" \
+         "$P_CLI psk=73776f726466697368 psk_identity=foo set_hostname=no debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -c "Certificate verification without having set hostname" \
+         -c "Certificate verification without CN verification" \
+         -C "get_hostname_for_verification() returned -" \
+         -C "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
+run_test "Authentication: hostname unset, client default, server picks PSK, 1.2" \
+         "$P_SRV force_version=tls12 force_ciphersuite=TLS-PSK-WITH-AES-128-CCM-8 psk=73776f726466697368 psk_identity=foo" \
+         "$P_CLI psk=73776f726466697368 psk_identity=foo set_hostname=no debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -C "Certificate verification without having set hostname" \
+         -C "Certificate verification without CN verification" \
+         -C "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
+requires_config_enabled MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_PSK_ENABLED
+run_test "Authentication: hostname unset, client default, server picks PSK, 1.3" \
+         "$P_SRV force_version=tls13 tls13_kex_modes=psk psk=73776f726466697368 psk_identity=foo" \
+         "$P_CLI psk=73776f726466697368 psk_identity=foo set_hostname=no debug_level=2" \
+         0 \
+         -C "does not match with the expected CN" \
+         -C "Certificate verification without having set hostname" \
+         -C "Certificate verification without CN verification" \
+         -C "x509_verify_cert() returned -" \
+         -C "X509 - Certificate verification failed"
+
 # The purpose of the next two tests is to test the client's behaviour when receiving a server
 # certificate with an unsupported elliptic curve. This should usually not happen because
 # the client informs the server about the supported curves - it does, though, in the
@@ -6418,7 +6686,6 @@ run_test    "Authentication: send alt hs DN hints in CertificateRequest" \
 # Tests for auth_mode, using CA callback, these are duplicated from the authentication tests
 # When updating these tests, modify the matching authentication tests accordingly
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: server badcert, client required" \
             "$P_SRV crt_file=$DATA_FILES_PATH/server5-badsign.crt \
              key_file=$DATA_FILES_PATH/server5.key" \
@@ -6430,7 +6697,6 @@ run_test    "Authentication, CA callback: server badcert, client required" \
             -c "! mbedtls_ssl_handshake returned" \
             -c "X509 - Certificate verification failed"
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: server badcert, client optional" \
             "$P_SRV crt_file=$DATA_FILES_PATH/server5-badsign.crt \
              key_file=$DATA_FILES_PATH/server5.key" \
@@ -6442,7 +6708,6 @@ run_test    "Authentication, CA callback: server badcert, client optional" \
             -C "! mbedtls_ssl_handshake returned" \
             -C "X509 - Certificate verification failed"
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: server badcert, client none" \
             "$P_SRV crt_file=$DATA_FILES_PATH/server5-badsign.crt \
              key_file=$DATA_FILES_PATH/server5.key" \
@@ -6461,7 +6726,6 @@ run_test    "Authentication, CA callback: server badcert, client none" \
 # occasion (to be fixed). If that bug's fixed, the test needs to be altered to use a
 # different means to have the server ignoring the client's supported curve list.
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: server ECDH p256v1, client required, p256v1 unsupported" \
             "$P_SRV debug_level=1 key_file=$DATA_FILES_PATH/server5.key \
              crt_file=$DATA_FILES_PATH/server5.ku-ka.crt" \
@@ -6472,7 +6736,6 @@ run_test    "Authentication, CA callback: server ECDH p256v1, client required, p
             -c "! Certificate verification flags" \
             -C "bad server certificate (ECDH curve)" # Expect failure at earlier verification stage
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: server ECDH p256v1, client optional, p256v1 unsupported" \
             "$P_SRV debug_level=1 key_file=$DATA_FILES_PATH/server5.key \
              crt_file=$DATA_FILES_PATH/server5.ku-ka.crt" \
@@ -6483,7 +6746,6 @@ run_test    "Authentication, CA callback: server ECDH p256v1, client optional, p
             -c "! Certificate verification flags"\
             -c "bad server certificate (ECDH curve)" # Expect failure only at ECDH params check
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 requires_any_configs_enabled $TLS1_2_KEY_EXCHANGES_WITH_CERT
 run_test    "Authentication, CA callback: client SHA384, server required" \
             "$P_SRV ca_callback=1 debug_level=3 auth_mode=required" \
@@ -6495,7 +6757,6 @@ run_test    "Authentication, CA callback: client SHA384, server required" \
             -c "Supported Signature Algorithm found: 04 " \
             -c "Supported Signature Algorithm found: 05 "
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 requires_any_configs_enabled $TLS1_2_KEY_EXCHANGES_WITH_CERT
 run_test    "Authentication, CA callback: client SHA256, server required" \
             "$P_SRV ca_callback=1 debug_level=3 auth_mode=required" \
@@ -6507,7 +6768,6 @@ run_test    "Authentication, CA callback: client SHA256, server required" \
             -c "Supported Signature Algorithm found: 04 " \
             -c "Supported Signature Algorithm found: 05 "
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: client badcert, server required" \
             "$P_SRV ca_callback=1 debug_level=3 auth_mode=required" \
             "$P_CLI debug_level=3 crt_file=$DATA_FILES_PATH/server5-badsign.crt \
@@ -6529,7 +6789,6 @@ run_test    "Authentication, CA callback: client badcert, server required" \
 # detect that its write end of the connection is closed and abort
 # before reading the alert message.
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: client cert not trusted, server required" \
             "$P_SRV ca_callback=1 debug_level=3 auth_mode=required" \
             "$P_CLI debug_level=3 crt_file=$DATA_FILES_PATH/server5-selfsigned.crt \
@@ -6547,7 +6806,6 @@ run_test    "Authentication, CA callback: client cert not trusted, server requir
             -s "! mbedtls_ssl_handshake returned" \
             -s "X509 - Certificate verification failed"
 
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: client badcert, server optional" \
             "$P_SRV ca_callback=1 debug_level=3 auth_mode=optional" \
             "$P_CLI debug_level=3 crt_file=$DATA_FILES_PATH/server5-badsign.crt \
@@ -6568,7 +6826,6 @@ run_test    "Authentication, CA callback: client badcert, server optional" \
 
 requires_config_value_equals "MBEDTLS_X509_MAX_INTERMEDIATE_CA" $MAX_IM_CA
 requires_full_size_output_buffer
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: server max_int chain, client default" \
             "$P_SRV crt_file=$DATA_FILES_PATH/dir-maxpath/c09.pem \
                     key_file=$DATA_FILES_PATH/dir-maxpath/09.key" \
@@ -6579,7 +6836,6 @@ run_test    "Authentication, CA callback: server max_int chain, client default"
 
 requires_config_value_equals "MBEDTLS_X509_MAX_INTERMEDIATE_CA" $MAX_IM_CA
 requires_full_size_output_buffer
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: server max_int+1 chain, client default" \
             "$P_SRV crt_file=$DATA_FILES_PATH/dir-maxpath/c10.pem \
                     key_file=$DATA_FILES_PATH/dir-maxpath/10.key" \
@@ -6590,7 +6846,6 @@ run_test    "Authentication, CA callback: server max_int+1 chain, client default
 
 requires_config_value_equals "MBEDTLS_X509_MAX_INTERMEDIATE_CA" $MAX_IM_CA
 requires_full_size_output_buffer
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: server max_int+1 chain, client optional" \
             "$P_SRV crt_file=$DATA_FILES_PATH/dir-maxpath/c10.pem \
                     key_file=$DATA_FILES_PATH/dir-maxpath/10.key" \
@@ -6602,7 +6857,6 @@ run_test    "Authentication, CA callback: server max_int+1 chain, client optiona
 
 requires_config_value_equals "MBEDTLS_X509_MAX_INTERMEDIATE_CA" $MAX_IM_CA
 requires_full_size_output_buffer
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: client max_int+1 chain, server optional" \
             "$P_SRV ca_callback=1 debug_level=3 ca_file=$DATA_FILES_PATH/dir-maxpath/00.crt auth_mode=optional" \
             "$P_CLI crt_file=$DATA_FILES_PATH/dir-maxpath/c10.pem \
@@ -6613,7 +6867,6 @@ run_test    "Authentication, CA callback: client max_int+1 chain, server optiona
 
 requires_config_value_equals "MBEDTLS_X509_MAX_INTERMEDIATE_CA" $MAX_IM_CA
 requires_full_size_output_buffer
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: client max_int+1 chain, server required" \
             "$P_SRV ca_callback=1 debug_level=3 ca_file=$DATA_FILES_PATH/dir-maxpath/00.crt auth_mode=required" \
             "$P_CLI crt_file=$DATA_FILES_PATH/dir-maxpath/c10.pem \
@@ -6624,7 +6877,6 @@ run_test    "Authentication, CA callback: client max_int+1 chain, server require
 
 requires_config_value_equals "MBEDTLS_X509_MAX_INTERMEDIATE_CA" $MAX_IM_CA
 requires_full_size_output_buffer
-requires_config_enabled MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK
 run_test    "Authentication, CA callback: client max_int chain, server required" \
             "$P_SRV ca_callback=1 debug_level=3 ca_file=$DATA_FILES_PATH/dir-maxpath/00.crt auth_mode=required" \
             "$P_CLI crt_file=$DATA_FILES_PATH/dir-maxpath/c09.pem \