schannel: allow verifyhost independently of verifypeer

Prior to this change if the user disabled the verify peer check then no
host check was done. Empirical testing shows
SCH_CRED_MANUAL_CRED_VALIDATION, which we use when peer verification is
disabled, also disables hostname verification.

In Windows < 8 our manual host verification check (ie the check used
when CA info is specified, or peer verification is disabled, or WinCE is
the OS) for schannel continues to only check the first subject alternate
name, and not all the names, since there is no easy way supported by the
API. It looks possible to do just more work, and should be addressed
separately.

Assisted-by: Daniel Stenberg
Reported-by: Martin Galvan

Fixes #3284
Closes #3285
Closes #xxxx

lib/vtls/schannel.c

@@ -1106,16 +1106,27 @@ schannel_connect_step2(struct connectdata *conn, int sockindex)
   if(pubkey_ptr) {
     result = pkp_pin_peer_pubkey(conn, sockindex, pubkey_ptr);
     if(result) {
-      failf(data, "SSL: public key does not match pinned public key!");
+      failf(data, "schannel: public key does not match pinned public key!");
       return result;
     }
   }
 
+  if(SSL_CONN_CONFIG(verifypeer)) {
+    /* If verifypeer is true then peer & host verify will be done automatically
+       by schannel except if use_manual_cred_validation is also true. */
 #ifdef HAS_MANUAL_VERIFY_API
-  if(conn->ssl_config.verifypeer && BACKEND->use_manual_cred_validation) {
-    return Curl_verify_certificate(conn, sockindex);
-  }
+    if(BACKEND->use_manual_cred_validation) {
+      result = Curl_verify_certificate(conn, sockindex);
+      if(result)
+        return result;
+    }
 #endif
+  }
+  else if(SSL_CONN_CONFIG(verifyhost)) {
+    result = Curl_verify_host(conn, sockindex);
+    if(result)
+      return result;
+  }
 
   return CURLE_OK;
 }

lib/vtls/schannel.h

@@ -53,6 +53,7 @@
 
 extern const struct Curl_ssl Curl_ssl_schannel;
 
+CURLcode Curl_verify_host(struct connectdata *conn, int sockindex);
 CURLcode Curl_verify_certificate(struct connectdata *conn, int sockindex);
 
 /* structs to expose only in schannel.c and schannel_verify.c */

lib/vtls/schannel_verify.c

@@ -37,8 +37,6 @@
 #define EXPOSE_SCHANNEL_INTERNAL_STRUCTS
 #include "schannel.h"
 
-#ifdef HAS_MANUAL_VERIFY_API
-
 #include "vtls.h"
 #include "sendf.h"
 #include "strerror.h"
@@ -53,6 +51,164 @@
 
 #define BACKEND connssl->backend
 
+#ifndef CERT_NAME_DISABLE_IE4_UTF8_FLAG
+#define CERT_NAME_DISABLE_IE4_UTF8_FLAG 0x00010000
+#endif
+
+#ifndef CERT_NAME_SEARCH_ALL_NAMES_FLAG
+#define CERT_NAME_SEARCH_ALL_NAMES_FLAG 0x2
+#endif
+
+CURLcode Curl_verify_host(struct connectdata *conn, int sockindex)
+{
+  SECURITY_STATUS status;
+  struct Curl_easy *data = conn->data;
+  struct ssl_connect_data *connssl = &conn->ssl[sockindex];
+  CURLcode result = CURLE_OK;
+  CERT_CONTEXT *pCertContextServer = NULL;
+  DWORD name_flags = 0;
+  TCHAR *cert_hostname_buff = NULL;
+  size_t cert_hostname_buff_index = 0;
+  DWORD len = 0;
+  DWORD actual_len = 0;
+  const char * const hostname = SSL_IS_PROXY() ?
+    conn->http_proxy.host.name : conn->host.name;
+  const char * const dispname = SSL_IS_PROXY() ?
+    conn->http_proxy.host.dispname : conn->host.dispname;
+
+  status = s_pSecFn->QueryContextAttributes(&BACKEND->ctxt->ctxt_handle,
+                                            SECPKG_ATTR_REMOTE_CERT_CONTEXT,
+                                            &pCertContextServer);
+
+  if((status != SEC_E_OK) || (pCertContextServer == NULL)) {
+    failf(data, "schannel: Failed to read remote certificate context: %s",
+          Curl_sspi_strerror(conn, status));
+    result = CURLE_PEER_FAILED_VERIFICATION;
+    goto cleanup;
+  }
+
+  /* CertGetNameString will provide the 8-bit character string without
+   * any decoding */
+  name_flags = CERT_NAME_DISABLE_IE4_UTF8_FLAG;
+
+  /* Request all dNSNames. Supported by Windows 8 or later. */
+  if(Curl_verify_windows_version(6, 2, PLATFORM_WINNT,
+                                 VERSION_GREATER_THAN_EQUAL)) {
+    name_flags |= CERT_NAME_SEARCH_ALL_NAMES_FLAG;
+  }
+
+  /* Determine the size of the string needed for the cert hostname */
+  len = CertGetNameString(pCertContextServer,
+                          CERT_NAME_DNS_TYPE,
+                          name_flags,
+                          NULL,
+                          NULL,
+                          0);
+  if(len == 0) {
+    failf(data,
+          "schannel: CertGetNameString() returned no "
+          "certificate name information");
+    result = CURLE_PEER_FAILED_VERIFICATION;
+    goto cleanup;
+  }
+
+  /* CertGetNameString guarantees that the returned name will not contain
+   * embedded null bytes. This appears to be undocumented behavior.
+   */
+  cert_hostname_buff = (LPTSTR)malloc(len * sizeof(TCHAR));
+  if(!cert_hostname_buff) {
+    result = CURLE_OUT_OF_MEMORY;
+    goto cleanup;
+  }
+  actual_len = CertGetNameString(pCertContextServer,
+                                 CERT_NAME_DNS_TYPE,
+                                 name_flags,
+                                 NULL,
+                                 (LPTSTR) cert_hostname_buff,
+                                 len);
+
+  /* Sanity check */
+  if(actual_len != len) {
+    failf(data,
+          "schannel: CertGetNameString() returned certificate "
+          "name information of unexpected size");
+    result = CURLE_PEER_FAILED_VERIFICATION;
+    goto cleanup;
+  }
+
+  /* If HAVE_CERT_NAME_SEARCH_ALL_NAMES is available, the output
+   * will contain all DNS names, where each name is null-terminated
+   * and the last DNS name is double null-terminated. Due to this
+   * encoding, use the length of the buffer to iterate over all names.
+   */
+  result = CURLE_PEER_FAILED_VERIFICATION;
+  while(cert_hostname_buff_index < len &&
+        cert_hostname_buff[cert_hostname_buff_index] != TEXT('\0') &&
+        result == CURLE_PEER_FAILED_VERIFICATION) {
+
+    char *cert_hostname;
+
+    /* Comparing the cert name and the connection hostname encoded as UTF-8
+     * is acceptable since both values are assumed to use ASCII
+     * (or some equivalent) encoding
+     */
+    cert_hostname = Curl_convert_tchar_to_UTF8(
+        &cert_hostname_buff[cert_hostname_buff_index]);
+    if(!cert_hostname) {
+      result = CURLE_OUT_OF_MEMORY;
+    }
+    else {
+      int match_result;
+
+      match_result = Curl_cert_hostcheck(cert_hostname, hostname);
+      if(match_result == CURL_HOST_MATCH) {
+        infof(data,
+              "schannel: connection hostname (%s) validated "
+              "against certificate name (%s)\n",
+              dispname, cert_hostname);
+        result = CURLE_OK;
+      }
+      else {
+        size_t cert_hostname_len;
+
+        infof(data,
+              "schannel: connection hostname (%s) did not match "
+              "against certificate name (%s)\n",
+              dispname, cert_hostname);
+
+        cert_hostname_len = _tcslen(
+            &cert_hostname_buff[cert_hostname_buff_index]);
+
+        /* Move on to next cert name */
+        cert_hostname_buff_index += cert_hostname_len + 1;
+
+        result = CURLE_PEER_FAILED_VERIFICATION;
+      }
+      Curl_unicodefree(cert_hostname);
+    }
+  }
+
+  if(result == CURLE_PEER_FAILED_VERIFICATION) {
+    failf(data,
+          "schannel: CertGetNameString() failed to match "
+          "connection hostname (%s) against server certificate names",
+          dispname);
+  }
+  else if(result != CURLE_OK)
+    failf(data, "schannel: server certificate name verification failed");
+
+cleanup:
+  if(pCertContextServer)
+    CertFreeCertificateContext(pCertContextServer);
+
+  Curl_unicodefree(cert_hostname_buff);
+
+  return result;
+}
+
+
+#ifdef HAS_MANUAL_VERIFY_API
+
 #define MAX_CAFILE_SIZE 1048576 /* 1 MiB */
 #define BEGIN_CERT "-----BEGIN CERTIFICATE-----"
 #define END_CERT "\n-----END CERTIFICATE-----"
@@ -282,129 +438,6 @@ cleanup:
   return result;
 }
 
-static CURLcode verify_host(struct Curl_easy *data,
-                            CERT_CONTEXT *pCertContextServer,
-                            const char * const conn_hostname)
-{
-  CURLcode result = CURLE_PEER_FAILED_VERIFICATION;
-  TCHAR *cert_hostname_buff = NULL;
-  size_t cert_hostname_buff_index = 0;
-  DWORD len = 0;
-  DWORD actual_len = 0;
-
-  /* CertGetNameString will provide the 8-bit character string without
-   * any decoding */
-  DWORD name_flags = CERT_NAME_DISABLE_IE4_UTF8_FLAG;
-
-#ifdef CERT_NAME_SEARCH_ALL_NAMES_FLAG
-  name_flags |= CERT_NAME_SEARCH_ALL_NAMES_FLAG;
-#endif
-
-  /* Determine the size of the string needed for the cert hostname */
-  len = CertGetNameString(pCertContextServer,
-                          CERT_NAME_DNS_TYPE,
-                          name_flags,
-                          NULL,
-                          NULL,
-                          0);
-  if(len == 0) {
-    failf(data,
-          "schannel: CertGetNameString() returned no "
-          "certificate name information");
-    result = CURLE_PEER_FAILED_VERIFICATION;
-    goto cleanup;
-  }
-
-  /* CertGetNameString guarantees that the returned name will not contain
-   * embedded null bytes. This appears to be undocumented behavior.
-   */
-  cert_hostname_buff = (LPTSTR)malloc(len * sizeof(TCHAR));
-  if(!cert_hostname_buff) {
-    result = CURLE_OUT_OF_MEMORY;
-    goto cleanup;
-  }
-  actual_len = CertGetNameString(pCertContextServer,
-                                 CERT_NAME_DNS_TYPE,
-                                 name_flags,
-                                 NULL,
-                                 (LPTSTR) cert_hostname_buff,
-                                 len);
-
-  /* Sanity check */
-  if(actual_len != len) {
-    failf(data,
-          "schannel: CertGetNameString() returned certificate "
-          "name information of unexpected size");
-    result = CURLE_PEER_FAILED_VERIFICATION;
-    goto cleanup;
-  }
-
-  /* If HAVE_CERT_NAME_SEARCH_ALL_NAMES is available, the output
-   * will contain all DNS names, where each name is null-terminated
-   * and the last DNS name is double null-terminated. Due to this
-   * encoding, use the length of the buffer to iterate over all names.
-   */
-  result = CURLE_PEER_FAILED_VERIFICATION;
-  while(cert_hostname_buff_index < len &&
-        cert_hostname_buff[cert_hostname_buff_index] != TEXT('\0') &&
-        result == CURLE_PEER_FAILED_VERIFICATION) {
-
-    char *cert_hostname;
-
-    /* Comparing the cert name and the connection hostname encoded as UTF-8
-     * is acceptable since both values are assumed to use ASCII
-     * (or some equivalent) encoding
-     */
-    cert_hostname = Curl_convert_tchar_to_UTF8(
-        &cert_hostname_buff[cert_hostname_buff_index]);
-    if(!cert_hostname) {
-      result = CURLE_OUT_OF_MEMORY;
-    }
-    else {
-      int match_result;
-
-      match_result = Curl_cert_hostcheck(cert_hostname, conn_hostname);
-      if(match_result == CURL_HOST_MATCH) {
-        infof(data,
-              "schannel: connection hostname (%s) validated "
-              "against certificate name (%s)\n",
-              conn_hostname, cert_hostname);
-        result = CURLE_OK;
-      }
-      else {
-        size_t cert_hostname_len;
-
-        infof(data,
-              "schannel: connection hostname (%s) did not match "
-              "against certificate name (%s)\n",
-              conn_hostname, cert_hostname);
-
-        cert_hostname_len = _tcslen(
-            &cert_hostname_buff[cert_hostname_buff_index]);
-
-        /* Move on to next cert name */
-        cert_hostname_buff_index += cert_hostname_len + 1;
-
-        result = CURLE_PEER_FAILED_VERIFICATION;
-      }
-      Curl_unicodefree(cert_hostname);
-    }
-  }
-
-  if(result == CURLE_PEER_FAILED_VERIFICATION) {
-    failf(data,
-          "schannel: CertGetNameString() failed to match "
-          "connection hostname (%s) against server certificate names",
-          conn_hostname);
-  }
-  else if(result != CURLE_OK)
-    failf(data, "schannel: server certificate name verification failed");
-
-cleanup:
-  Curl_unicodefree(cert_hostname_buff);
-
-  return result;
-}
 
 CURLcode Curl_verify_certificate(struct connectdata *conn, int sockindex)
 {
@@ -416,9 +449,11 @@ CURLcode Curl_verify_certificate(struct connectdata *conn, int sockindex)
   const CERT_CHAIN_CONTEXT *pChainContext = NULL;
   HCERTCHAINENGINE cert_chain_engine = NULL;
   HCERTSTORE trust_store = NULL;
-  const char * const conn_hostname = SSL_IS_PROXY() ?
-    conn->http_proxy.host.name :
-    conn->host.name;
+  CERT_CHAIN_PARA ChainPara = { 0 };
+  CERT_SIMPLE_CHAIN *pSimpleChain = NULL;
+  DWORD dwTrustErrorMask = 0;
+
+  ChainPara.cbSize = sizeof(ChainPara);
 
   status = s_pSecFn->QueryContextAttributes(&BACKEND->ctxt->ctxt_handle,
                                             SECPKG_ATTR_REMOTE_CERT_CONTEXT,
@@ -428,10 +463,10 @@ CURLcode Curl_verify_certificate(struct connectdata *conn, int sockindex)
     failf(data, "schannel: Failed to read remote certificate context: %s",
           Curl_sspi_strerror(conn, status));
     result = CURLE_PEER_FAILED_VERIFICATION;
+    goto cleanup;
   }
 
-  if(result == CURLE_OK && SSL_CONN_CONFIG(CAfile) &&
-      BACKEND->use_manual_cred_validation) {
+  if(SSL_CONN_CONFIG(CAfile) && BACKEND->use_manual_cred_validation) {
     /*
      * Create a chain engine that uses the certificates in the CA file as
      * trusted certificates. This is only supported on Windows 7+.
@@ -441,26 +476,33 @@ CURLcode Curl_verify_certificate(struct connectdata *conn, int sockindex)
       failf(data, "schannel: this version of Windows is too old to support "
             "certificate verification via CA bundle file.");
       result = CURLE_SSL_CACERT_BADFILE;
+      goto cleanup;
     }
-    else {
-      /* Open the certificate store */
-      trust_store = CertOpenStore(CERT_STORE_PROV_MEMORY,
-                                  0,
-                                  (HCRYPTPROV)NULL,
-                                  CERT_STORE_CREATE_NEW_FLAG,
-                                  NULL);
-      if(!trust_store) {
-        failf(data, "schannel: failed to create certificate store: %s",
-              Curl_strerror(conn, GetLastError()));
-        result = CURLE_SSL_CACERT_BADFILE;
-      }
-      else {
-        result = add_certs_to_store(trust_store, SSL_CONN_CONFIG(CAfile),
-                                    conn);
-      }
+
+    /* Open the certificate store */
+    trust_store = CertOpenStore(CERT_STORE_PROV_MEMORY,
+                                0,
+                                (HCRYPTPROV)NULL,
+                                CERT_STORE_CREATE_NEW_FLAG,
+                                NULL);
+    if(!trust_store) {
+      failf(data, "schannel: failed to create certificate store: %s",
+            Curl_strerror(conn, GetLastError()));
+      result = CURLE_SSL_CACERT_BADFILE;
+      goto cleanup;
     }
 
-    if(result == CURLE_OK) {
+    result = add_certs_to_store(trust_store, SSL_CONN_CONFIG(CAfile),
+                                conn);
+    if(result)
+      goto cleanup;
+
+    /* CertCreateCertificateChainEngine will check the expected size of the
+     * CERT_CHAIN_ENGINE_CONFIG structure and fail if the specified size
+     * does not match the expected size. When this occurs, it indicates that
+     * CAINFO is not supported on the version of Windows in use.
+     */
+    {
       CERT_CHAIN_ENGINE_CONFIG_WIN7 engine_config;
       BOOL create_engine_result;
 
@@ -468,11 +510,6 @@ CURLcode Curl_verify_certificate(struct connectdata *conn, int sockindex)
       engine_config.cbSize = sizeof(engine_config);
       engine_config.hExclusiveRoot = trust_store;
 
-      /* CertCreateCertificateChainEngine will check the expected size of the
-       * CERT_CHAIN_ENGINE_CONFIG structure and fail if the specified size
-       * does not match the expected size. When this occurs, it indicates that
-       * CAINFO is not supported on the version of Windows in use.
-       */
       create_engine_result =
         CertCreateCertificateChainEngine(
           (CERT_CHAIN_ENGINE_CONFIG *)&engine_config, &cert_chain_engine);
@@ -481,72 +518,65 @@ CURLcode Curl_verify_certificate(struct connectdata *conn, int sockindex)
               "schannel: failed to create certificate chain engine: %s",
               Curl_strerror(conn, GetLastError()));
         result = CURLE_SSL_CACERT_BADFILE;
+        goto cleanup;
       }
     }
   }
 
-  if(result == CURLE_OK) {
-    CERT_CHAIN_PARA ChainPara;
-
-    memset(&ChainPara, 0, sizeof(ChainPara));
-    ChainPara.cbSize = sizeof(ChainPara);
-
-    if(!CertGetCertificateChain(cert_chain_engine,
-                                pCertContextServer,
-                                NULL,
-                                pCertContextServer->hCertStore,
-                                &ChainPara,
-                                (data->set.ssl.no_revoke ? 0 :
-                                 CERT_CHAIN_REVOCATION_CHECK_CHAIN),
-                                NULL,
-                                &pChainContext)) {
-      failf(data, "schannel: CertGetCertificateChain failed: %s",
-            Curl_sspi_strerror(conn, GetLastError()));
-      pChainContext = NULL;
-      result = CURLE_PEER_FAILED_VERIFICATION;
-    }
+  if(!CertGetCertificateChain(cert_chain_engine,
+                              pCertContextServer,
+                              NULL,
+                              pCertContextServer->hCertStore,
+                              &ChainPara,
+                              (data->set.ssl.no_revoke ? 0 :
+                               CERT_CHAIN_REVOCATION_CHECK_CHAIN),
+                              NULL,
+                              &pChainContext)) {
+    failf(data, "schannel: CertGetCertificateChain failed: %s",
+          Curl_sspi_strerror(conn, GetLastError()));
+    pChainContext = NULL;
+    result = CURLE_PEER_FAILED_VERIFICATION;
+    goto cleanup;
+  }
 
-    if(result == CURLE_OK) {
-      CERT_SIMPLE_CHAIN *pSimpleChain = pChainContext->rgpChain[0];
-      DWORD dwTrustErrorMask = ~(DWORD)(CERT_TRUST_IS_NOT_TIME_NESTED);
-      dwTrustErrorMask &= pSimpleChain->TrustStatus.dwErrorStatus;
-      if(dwTrustErrorMask) {
-        if(dwTrustErrorMask & CERT_TRUST_IS_REVOKED)
-          failf(data, "schannel: CertGetCertificateChain trust error"
-                " CERT_TRUST_IS_REVOKED");
-        else if(dwTrustErrorMask & CERT_TRUST_IS_PARTIAL_CHAIN)
-          failf(data, "schannel: CertGetCertificateChain trust error"
-                " CERT_TRUST_IS_PARTIAL_CHAIN");
-        else if(dwTrustErrorMask & CERT_TRUST_IS_UNTRUSTED_ROOT)
-          failf(data, "schannel: CertGetCertificateChain trust error"
-                " CERT_TRUST_IS_UNTRUSTED_ROOT");
-        else if(dwTrustErrorMask & CERT_TRUST_IS_NOT_TIME_VALID)
-          failf(data, "schannel: CertGetCertificateChain trust error"
-                " CERT_TRUST_IS_NOT_TIME_VALID");
-        else if(dwTrustErrorMask & CERT_TRUST_REVOCATION_STATUS_UNKNOWN)
-          failf(data, "schannel: CertGetCertificateChain trust error"
-                " CERT_TRUST_REVOCATION_STATUS_UNKNOWN");
-        else
-          failf(data, "schannel: CertGetCertificateChain error mask: 0x%08x",
-                dwTrustErrorMask);
-        result = CURLE_PEER_FAILED_VERIFICATION;
-      }
-    }
+  pSimpleChain = pChainContext->rgpChain[0];
+  dwTrustErrorMask = ~(DWORD)(CERT_TRUST_IS_NOT_TIME_NESTED);
+  dwTrustErrorMask &= pSimpleChain->TrustStatus.dwErrorStatus;
+  if(dwTrustErrorMask) {
+    if(dwTrustErrorMask & CERT_TRUST_IS_REVOKED)
+      failf(data, "schannel: CertGetCertificateChain trust error"
+            " CERT_TRUST_IS_REVOKED");
+    else if(dwTrustErrorMask & CERT_TRUST_IS_PARTIAL_CHAIN)
+      failf(data, "schannel: CertGetCertificateChain trust error"
+            " CERT_TRUST_IS_PARTIAL_CHAIN");
+    else if(dwTrustErrorMask & CERT_TRUST_IS_UNTRUSTED_ROOT)
+      failf(data, "schannel: CertGetCertificateChain trust error"
+            " CERT_TRUST_IS_UNTRUSTED_ROOT");
+    else if(dwTrustErrorMask & CERT_TRUST_IS_NOT_TIME_VALID)
+      failf(data, "schannel: CertGetCertificateChain trust error"
+            " CERT_TRUST_IS_NOT_TIME_VALID");
+    else if(dwTrustErrorMask & CERT_TRUST_REVOCATION_STATUS_UNKNOWN)
+      failf(data, "schannel: CertGetCertificateChain trust error"
+            " CERT_TRUST_REVOCATION_STATUS_UNKNOWN");
+    else
+      failf(data, "schannel: CertGetCertificateChain error mask: 0x%08x",
+            dwTrustErrorMask);
+    result = CURLE_PEER_FAILED_VERIFICATION;
+    goto cleanup;
   }
 
-  if(result == CURLE_OK) {
-    if(SSL_CONN_CONFIG(verifyhost)) {
-      result = verify_host(conn->data, pCertContextServer, conn_hostname);
-    }
+  if(SSL_CONN_CONFIG(verifyhost)) {
+    result = Curl_verify_host(conn, sockindex);
+    if(result)
+      goto cleanup;
   }
 
-  if(cert_chain_engine) {
+cleanup:
+  if(cert_chain_engine)
     CertFreeCertificateChainEngine(cert_chain_engine);
-  }
 
-  if(trust_store) {
+  if(trust_store)
     CertCloseStore(trust_store, 0);
-  }
 
   if(pChainContext)
     CertFreeCertificateChain(pChainContext);