coap_openhitls.c: prefer SAN before CN for certificate names

.github/workflows/main.yml

@@ -18,7 +18,7 @@ env:
   FORCE_JAVASCRIPT_ACTIONS_TO_NODE24: true
   OPENHITLS_REPO: https://gitcode.com/openHiTLS/openhitls.git
   # Pinned until the next openHiTLS release
-  OPENHITLS_REF: 0a7d5a3748f94c594832a16a7a970cb19d8b4b12
+  OPENHITLS_REF: 2d524d8e0f9c392a4bc3c244f976a69f9f6bb64a
 
 jobs:
   pre-commit:

examples/tls_backend_testcases.sh

@@ -29,6 +29,8 @@
 # - PKI invalid root CA directory negative path
 # - concurrent PSK and PKI server configuration
 # - PKI missing client certificate negative path
+# - PKI SAN preferred over CN
+# - PKI CN fallback without SAN
 # - PKI SNI certificate selection
 # - wrong PKI CA negative path
 #
@@ -322,6 +324,8 @@ generate_pki_files () {
   ca_conf=$pki_dir/ca.cnf
   server_conf=$pki_dir/server.cnf
   alt_server_conf=$pki_dir/alt_server.cnf
+  san_server_conf=$pki_dir/san_server.cnf
+  cn_server_conf=$pki_dir/cn_server.cnf
   sni_server_conf=$pki_dir/sni_server.cnf
   client_conf=$pki_dir/client.cnf
   inter_conf=$pki_dir/inter.cnf
@@ -331,6 +335,10 @@ generate_pki_files () {
   if [ -f "$pki_dir/server.pem" ] &&
      [ -f "$pki_dir/self_server.pem" ] &&
      [ -f "$pki_dir/alt_server.pem" ] &&
+     [ -f "$pki_dir/san_server.pem" ] &&
+     [ -f "$pki_dir/san_server.key" ] &&
+     [ -f "$pki_dir/cn_server.pem" ] &&
+     [ -f "$pki_dir/cn_server.key" ] &&
      [ -f "$pki_dir/sni_combined.pem" ] &&
      [ -f "$pki_dir/chain_server.pem" ] &&
      [ -f "$pki_dir/chain_depth_ok_server.pem" ] &&
@@ -392,6 +400,40 @@ subjectAltName = @alt_names
 
 [alt_names]
 DNS.1 = default.invalid
+EOF
+
+  cat > "$san_server_conf" <<EOF
+[req]
+distinguished_name = dn
+req_extensions = v3_req
+prompt = no
+
+[dn]
+CN = default.invalid
+
+[v3_req]
+basicConstraints = CA:false
+keyUsage = critical,digitalSignature,keyEncipherment
+extendedKeyUsage = serverAuth
+subjectAltName = @alt_names
+
+[alt_names]
+DNS.1 = $SNI_HOST
+EOF
+
+  cat > "$cn_server_conf" <<EOF
+[req]
+distinguished_name = dn
+req_extensions = v3_req
+prompt = no
+
+[dn]
+CN = $SNI_HOST
+
+[v3_req]
+basicConstraints = CA:false
+keyUsage = critical,digitalSignature,keyEncipherment
+extendedKeyUsage = serverAuth
 EOF
 
   cat > "$sni_server_conf" <<EOF
@@ -454,6 +496,22 @@ EOF
     -out "$pki_dir/alt_server.pem" -days 1 -sha256 \
     -extensions v3_req -extfile "$alt_server_conf" \
     >> "$LOGDIR/$case_name.openssl" 2>&1 || return 1
+  openssl req -new -newkey rsa:2048 -nodes -sha256 \
+    -keyout "$pki_dir/san_server.key" -out "$pki_dir/san_server.csr" \
+    -config "$san_server_conf" >> "$LOGDIR/$case_name.openssl" 2>&1 || return 1
+  openssl x509 -req -in "$pki_dir/san_server.csr" \
+    -CA "$pki_dir/ca.pem" -CAkey "$pki_dir/ca.key" -CAcreateserial \
+    -out "$pki_dir/san_server.pem" -days 1 -sha256 \
+    -extensions v3_req -extfile "$san_server_conf" \
+    >> "$LOGDIR/$case_name.openssl" 2>&1 || return 1
+  openssl req -new -newkey rsa:2048 -nodes -sha256 \
+    -keyout "$pki_dir/cn_server.key" -out "$pki_dir/cn_server.csr" \
+    -config "$cn_server_conf" >> "$LOGDIR/$case_name.openssl" 2>&1 || return 1
+  openssl x509 -req -in "$pki_dir/cn_server.csr" \
+    -CA "$pki_dir/ca.pem" -CAkey "$pki_dir/ca.key" -CAcreateserial \
+    -out "$pki_dir/cn_server.pem" -days 1 -sha256 \
+    -extensions v3_req -extfile "$cn_server_conf" \
+    >> "$LOGDIR/$case_name.openssl" 2>&1 || return 1
   openssl req -new -newkey rsa:2048 -nodes -sha256 \
     -keyout "$pki_dir/sni_server.key" -out "$pki_dir/sni_server.csr" \
     -config "$sni_server_conf" >> "$LOGDIR/$case_name.openssl" 2>&1 || return 1
@@ -1471,6 +1529,60 @@ run_pki_missing_client_cert () {
   fi
 }
 
+run_pki_san_preferred_over_cn () {
+  case_name=pki_san_preferred_over_cn
+  echo -n "PKI SAN preferred over CN - "
+  pki_dir=$LOGDIR/pki
+
+  if ! generate_pki_files "$case_name"; then
+    fail_case "$case_name" "certificate generation failed"
+    return
+  fi
+  if ! start_pki_server "$case_name" "$pki_dir/san_server.pem" \
+      "$pki_dir/san_server.key"; then
+    fail_case "$case_name" "server did not start"
+    return
+  fi
+
+  run_pki_client "$case_name" "$pki_dir/ca.pem" "$CLIENT_TIMEOUT"
+
+  if assert_contains "$LOGDIR/$case_name.client" "COAP_EVENT_DTLS_CONNECTED" &&
+     assert_contains "$LOGDIR/$case_name.client" "2\\.05" &&
+     assert_contains "$LOGDIR/$case_name.client" "CN '$SNI_HOST' presented by server" &&
+     assert_contains "$LOGDIR/$case_name.server" "call handler for pseudo resource '.well-known/core'"; then
+    pass_case
+  else
+    fail_case "$case_name" "PKI SAN did not override mismatching CN"
+  fi
+}
+
+run_pki_cn_fallback () {
+  case_name=pki_cn_fallback
+  echo -n "PKI CN fallback without SAN - "
+  pki_dir=$LOGDIR/pki
+
+  if ! generate_pki_files "$case_name"; then
+    fail_case "$case_name" "certificate generation failed"
+    return
+  fi
+  if ! start_pki_server "$case_name" "$pki_dir/cn_server.pem" \
+      "$pki_dir/cn_server.key"; then
+    fail_case "$case_name" "server did not start"
+    return
+  fi
+
+  run_pki_client "$case_name" "$pki_dir/ca.pem" "$CLIENT_TIMEOUT"
+
+  if assert_contains "$LOGDIR/$case_name.client" "COAP_EVENT_DTLS_CONNECTED" &&
+     assert_contains "$LOGDIR/$case_name.client" "2\\.05" &&
+     assert_contains "$LOGDIR/$case_name.client" "CN '$SNI_HOST' presented by server" &&
+     assert_contains "$LOGDIR/$case_name.server" "call handler for pseudo resource '.well-known/core'"; then
+    pass_case
+  else
+    fail_case "$case_name" "PKI CN fallback without SAN did not complete"
+  fi
+}
+
 run_pki_sni () {
   case_name=pki_sni
   echo -n "PKI SNI certificate selection - "
@@ -1557,6 +1669,8 @@ run_pki_root_ca_file_invalid
 run_pki_root_ca_dir_invalid
 run_psk_pki_dual_mode
 run_pki_missing_client_cert
+run_pki_san_preferred_over_cn
+run_pki_cn_fallback
 run_pki_sni
 run_wrong_pki_ca
 

src/coap_openhitls.c

@@ -49,6 +49,7 @@
 #include <hitls/pki/hitls_pki_cert.h>
 #include <hitls/pki/hitls_pki_errno.h>
 #include <hitls/pki/hitls_pki_types.h>
+#include <hitls/pki/hitls_pki_utils.h>
 #include <hitls/pki/hitls_pki_x509.h>
 #if defined(__GNUC__)
 #pragma GCC diagnostic pop
@@ -787,6 +788,76 @@ coap_hitls_verify_cb_self_signed_allowed(const coap_dtls_pki_t *setup_data,
          depth == 0 && coap_hitls_cert_is_self_signed(cert);
 }
 
+static char *
+coap_hitls_copy_name(const uint8_t *data, uint32_t data_len) {
+  char *copy;
+  size_t len = (size_t)data_len;
+
+  if (data_len && !data)
+    return NULL;
+  copy = (char *)coap_malloc_type(COAP_STRING, len + 1);
+  if (!copy)
+    return NULL;
+  if (len)
+    memcpy(copy, data, len);
+  copy[len] = '\000';
+  return copy;
+}
+
+static char *
+coap_hitls_get_san_from_cert(HITLS_X509_Cert *cert) {
+  HITLS_X509_ExtSan san = {0};
+  char *dns_name = NULL;
+
+  if (HITLS_X509_CertCtrl(cert, HITLS_X509_EXT_GET_SAN, &san,
+                          sizeof(san)) == HITLS_PKI_SUCCESS &&
+      san.names) {
+    for (BslListNode *name_node = BSL_LIST_FirstNode(san.names);
+         name_node != NULL;
+         name_node = BSL_LIST_GetNextNode(san.names, name_node)) {
+      const HITLS_X509_GeneralName *name =
+          (const HITLS_X509_GeneralName *)BSL_LIST_GetData(name_node);
+
+      if (!name || name->type != HITLS_X509_GN_DNS)
+        continue;
+      if (name->value.dataLen &&
+          memchr(name->value.data, '\000', name->value.dataLen))
+        continue;
+      dns_name = coap_hitls_copy_name(name->value.data, name->value.dataLen);
+      break;
+    }
+  }
+
+  HITLS_X509_ClearSubjectAltName(&san);
+  return dns_name;
+}
+
+static char *
+coap_hitls_get_cn_from_cert(HITLS_X509_Cert *cert) {
+  BSL_Buffer cn = {0};
+  char *cn_name = NULL;
+
+  if (HITLS_X509_CertCtrl(cert, HITLS_X509_GET_SUBJECT_CN_STR,
+                          &cn, sizeof(cn)) == HITLS_PKI_SUCCESS) {
+    cn_name = coap_hitls_copy_name(cn.data, cn.dataLen);
+  }
+  if (cn.data)
+    BSL_SAL_Free(cn.data);
+  return cn_name;
+}
+
+static char *
+coap_hitls_get_san_or_cn_from_cert(HITLS_X509_Cert *cert) {
+  char *name;
+
+  if (!cert)
+    return NULL;
+  name = coap_hitls_get_san_from_cert(cert);
+  if (name)
+    return name;
+  return coap_hitls_get_cn_from_cert(cert);
+}
+
 static int
 coap_hitls_validate_cn_cert(coap_session_t *session,
                             const coap_dtls_pki_t *setup_data,
@@ -795,32 +866,30 @@ coap_hitls_validate_cn_cert(coap_session_t *session,
                             int validated) {
   uint8_t *der = NULL;
   uint32_t der_len = 0;
-  BSL_Buffer cn;
+  char *san_or_cn;
   int ret = 1;
 
-  memset(&cn, 0, sizeof(cn));
   (void)HITLS_X509_CertCtrl(cert, HITLS_X509_GET_ENCODELEN,
                             &der_len, sizeof(der_len));
   if (der_len)
     (void)HITLS_X509_CertCtrl(cert, HITLS_X509_GET_ENCODE,
                               &der, sizeof(der));
-  (void)HITLS_X509_CertCtrl(cert, HITLS_X509_GET_SUBJECT_CN_STR,
-                            &cn, sizeof(cn));
+  san_or_cn = coap_hitls_get_san_or_cn_from_cert(cert);
 
   if (setup_data->validate_cn_call_back) {
     coap_lock_callback_ret(ret,
                            setup_data->validate_cn_call_back(
-                               cn.data ? (const char *)cn.data : "",
+                               san_or_cn ? san_or_cn : "",
                                der, der_len, session, depth, validated,
                                setup_data->cn_call_back_arg));
   }
   if (depth == 0 && session->type == COAP_SESSION_TYPE_CLIENT &&
       setup_data->client_sni && !setup_data->allow_sni_cn_mismatch &&
-      cn.data && strcmp((const char *)cn.data, setup_data->client_sni)) {
+      san_or_cn && strcmp(san_or_cn, setup_data->client_sni)) {
     ret = 0;
   }
-  if (cn.data)
-    BSL_SAL_Free(cn.data);
+  if (san_or_cn)
+    coap_free_type(COAP_STRING, san_or_cn);
   return ret;
 }