GnuTLS: full-chain OCSP stapling. Bug 1466
[exim.git] / src / src / tls-gnu.c
index de44313e80b01d9fa4885da38a501e9bf4165245..52128b940b922d2126bcfacba7eec949719e676c 100644 (file)
@@ -76,6 +76,11 @@ require current GnuTLS, then we'll drop support for the ancient libraries).
 #if GNUTLS_VERSION_NUMBER >= 0x030506 && !defined(DISABLE_OCSP)
 # define SUPPORT_SRV_OCSP_STACK
 #endif
+#if GNUTLS_VERSION_NUMBER >= 0x030603
+# define EXIM_HAVE_TLS1_3
+# define SUPPORT_GNUTLS_EXT_RAW_PARSE
+# define GNUTLS_OCSP_STATUS_REQUEST_GET2
+#endif
 
 #ifdef SUPPORT_DANE
 # if GNUTLS_VERSION_NUMBER >= 0x030000
@@ -112,6 +117,9 @@ options_tls(void)
 # ifdef EXPERIMENTAL_TLS_RESUME
 builtin_macro_create_var(US"_RESUME_DECODE", RESUME_DECODE_STRING );
 # endif
+# ifdef EXIM_HAVE_TLS1_3
+builtin_macro_create(US"_HAVE_TLS1_3");
+# endif
 }
 #else
 
@@ -225,6 +233,7 @@ static BOOL exim_gnutls_base_init_done = FALSE;
 
 #ifndef DISABLE_OCSP
 static BOOL gnutls_buggy_ocsp = FALSE;
+static BOOL exim_testharness_disable_ocsp_validity_check = FALSE;
 #endif
 
 #ifdef EXPERIMENTAL_TLS_RESUME
@@ -287,11 +296,16 @@ static void exim_gnutls_logger_cb(int level, const char *message);
 
 static int exim_sni_handling_cb(gnutls_session_t session);
 
-#ifndef DISABLE_OCSP
+#if !defined(DISABLE_OCSP)
 static int server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
   gnutls_datum_t * ocsp_response);
 #endif
 
+#ifdef EXPERIMENTAL_TLS_RESUME
+static int
+tls_server_ticket_cb(gnutls_session_t sess, u_int htype, unsigned when,
+  unsigned incoming, const gnutls_datum_t * msg);
+#endif
 
 
 /* Daemon one-time initialisation */
@@ -868,6 +882,125 @@ return -rc;
 }
 
 
+#ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
+/* Make a note that we saw a status-request */
+static int
+tls_server_clienthello_ext(void * ctx, unsigned tls_id,
+  const unsigned char *data, unsigned size)
+{
+/* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
+if (tls_id == 5)       /* status_request */
+  {
+  DEBUG(D_tls) debug_printf("Seen status_request extension from client\n");
+  tls_in.ocsp = OCSP_NOT_RESP;
+  }
+return 0;
+}
+
+/* Callback for client-hello, on server, if we think we might serve stapled-OCSP */
+static int
+tls_server_clienthello_cb(gnutls_session_t session, unsigned int htype,
+  unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
+{
+/* Call fn for each extension seen.  3.6.3 onwards */
+return gnutls_ext_raw_parse(NULL, tls_server_clienthello_ext, msg,
+                          GNUTLS_EXT_RAW_FLAG_TLS_CLIENT_HELLO);
+}
+
+
+/* Make a note that we saw a status-response */
+static int
+tls_server_servercerts_ext(void * ctx, unsigned tls_id,
+  const unsigned char *data, unsigned size)
+{
+/* debug_printf("%s %u\n", __FUNCTION__, tls_id); */
+/* https://www.iana.org/assignments/tls-extensiontype-values/tls-extensiontype-values.xhtml */
+if (FALSE && tls_id == 5)      /* status_request */
+  {
+  DEBUG(D_tls) debug_printf("Seen status_request extension\n");
+  tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
+    ? OCSP_VFY_NOT_TRIED : OCSP_VFIED; /* We know that GnuTLS verifies responses */
+  }
+return 0;
+}
+
+/* Callback for certificates packet, on server, if we think we might serve stapled-OCSP */
+static int
+tls_server_servercerts_cb(gnutls_session_t session, unsigned int htype,
+  unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
+{
+/* Call fn for each extension seen.  3.6.3 onwards */
+#ifdef notdef
+/*XXX crashes */
+return gnutls_ext_raw_parse(NULL, tls_server_servercerts_ext, msg, 0);
+#endif
+}
+#endif
+
+/*XXX in tls1.3 the cert-status travel as an extension next to the cert, in the
+ "Handshake Protocol: Certificate" record.
+So we need to spot the Certificate handshake message, parse it and spot any status_request extension(s)
+
+This is different to tls1.2 - where it is a separate record (wireshake term) / handshake message (gnutls term).
+*/
+
+#if defined(EXPERIMENTAL_TLS_RESUME) || defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
+/* Callback for certificate-status, on server. We sent stapled OCSP. */
+static int
+tls_server_certstatus_cb(gnutls_session_t session, unsigned int htype,
+  unsigned when, unsigned int incoming, const gnutls_datum_t * msg)
+{
+DEBUG(D_tls) debug_printf("Sending certificate-status\n");             /*XXX we get this for tls1.2 but not for 1.3 */
+#ifdef SUPPORT_SRV_OCSP_STACK
+tls_in.ocsp = exim_testharness_disable_ocsp_validity_check
+  ? OCSP_VFY_NOT_TRIED : OCSP_VFIED;   /* We know that GnuTLS verifies responses */
+#else
+tls_in.ocsp = OCSP_VFY_NOT_TRIED;
+#endif
+return 0;
+}
+
+/* Callback for handshake messages, on server */
+static int
+tls_server_hook_cb(gnutls_session_t sess, u_int htype, unsigned when,
+  unsigned incoming, const gnutls_datum_t * msg)
+{
+/* debug_printf("%s: htype %u\n", __FUNCTION__, htype); */
+switch (htype)
+  {
+# ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
+  case GNUTLS_HANDSHAKE_CLIENT_HELLO:
+    return tls_server_clienthello_cb(sess, htype, when, incoming, msg);
+  case GNUTLS_HANDSHAKE_CERTIFICATE_PKT:
+    return tls_server_servercerts_cb(sess, htype, when, incoming, msg);
+# endif
+  case GNUTLS_HANDSHAKE_CERTIFICATE_STATUS:
+    return tls_server_certstatus_cb(sess, htype, when, incoming, msg);
+# ifdef EXPERIMENTAL_TLS_RESUME
+  case GNUTLS_HANDSHAKE_NEW_SESSION_TICKET:
+    return tls_server_ticket_cb(sess, htype, when, incoming, msg);
+# endif
+  default:
+    return 0;
+  }
+}
+#endif
+
+
+#if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
+static void
+tls_server_testharness_ocsp_fiddle(void)
+{
+extern char ** environ;
+if (environ) for (uschar ** p = USS environ; *p; p++)
+  if (Ustrncmp(*p, "EXIM_TESTHARNESS_DISABLE_OCSPVALIDITYCHECK", 42) == 0)
+    {
+    DEBUG(D_tls) debug_printf("Permitting known bad OCSP response\n");
+    exim_testharness_disable_ocsp_validity_check = TRUE;
+    }
+}
+#endif
+
 /*************************************************
 *       Variables re-expanded post-SNI           *
 *************************************************/
@@ -928,6 +1061,18 @@ if ((rc = gnutls_certificate_allocate_credentials(&state->x509_cred)))
 
 #ifdef SUPPORT_SRV_OCSP_STACK
 gnutls_certificate_set_flags(state->x509_cred, GNUTLS_CERTIFICATE_API_V2);
+
+# if !defined(DISABLE_OCSP) && defined(SUPPORT_GNUTLS_EXT_RAW_PARSE)
+if (!host && tls_ocsp_file)
+  {
+  if (f.running_in_test_harness)
+    tls_server_testharness_ocsp_fiddle();
+
+  if (exim_testharness_disable_ocsp_validity_check)
+    gnutls_certificate_set_flags(state->x509_cred,
+      GNUTLS_CERTIFICATE_API_V2 | GNUTLS_CERTIFICATE_SKIP_OCSP_RESPONSE_CHECK);
+  }
+# endif
 #endif
 
 /* remember: expand_check_tlsvar() is expand_check() but fiddling with
@@ -955,7 +1100,7 @@ if (state->tls_privatekey && !expand_check_tlsvar(tls_privatekey, errstr))
 
 /* tls_privatekey is optional, defaulting to same file as certificate */
 
-if (state->tls_privatekey == NULL || *state->tls_privatekey == '\0')
+if (!state->tls_privatekey || !*state->tls_privatekey)
   {
   state->tls_privatekey = state->tls_certificate;
   state->exp_tls_privatekey = state->exp_tls_certificate;
@@ -986,8 +1131,11 @@ if (state->exp_tls_certificate && *state->exp_tls_certificate)
     const uschar * olist;
     int csep = 0, ksep = 0, osep = 0, cnt = 0;
     uschar * cfile, * kfile, * ofile;
-
 #ifndef DISABLE_OCSP
+# ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
+    gnutls_x509_crt_fmt_t ocsp_fmt = GNUTLS_X509_FMT_DER;
+# endif
+
     if (!expand_check(tls_ocsp_file, US"tls_ocsp_file", &ofile, errstr))
       return DEFER;
     olist = ofile;
@@ -1002,12 +1150,13 @@ if (state->exp_tls_certificate && *state->exp_tls_certificate)
       else
        {
        int gnutls_cert_index = -rc;
-       DEBUG(D_tls) debug_printf("TLS: cert/key %s registered\n", cfile);
-
-       /* Set the OCSP stapling server info */
+       DEBUG(D_tls) debug_printf("TLS: cert/key %d %s registered\n",
+                                 gnutls_cert_index, cfile);
 
 #ifndef DISABLE_OCSP
        if (tls_ocsp_file)
+         {
+         /* Set the OCSP stapling server info */
          if (gnutls_buggy_ocsp)
            {
            DEBUG(D_tls)
@@ -1015,37 +1164,63 @@ if (state->exp_tls_certificate && *state->exp_tls_certificate)
            }
          else if ((ofile = string_nextinlist(&olist, &osep, NULL, 0)))
            {
-           /* Use the full callback method for stapling just to get
-           observability.  More efficient would be to read the file once only,
-           if it never changed (due to SNI). Would need restart on file update,
-           or watch datestamp.  */
+           DEBUG(D_tls) debug_printf("OCSP response file %d  = %s\n",
+                                     gnutls_cert_index, ofile);
+# ifdef SUPPORT_GNUTLS_EXT_RAW_PARSE
+           if (Ustrncmp(ofile, US"PEM ", 4) == 0)
+             {
+             ocsp_fmt = GNUTLS_X509_FMT_PEM;
+             ofile += 4;
+             }
+           else if (Ustrncmp(ofile, US"DER ", 4) == 0)
+             {
+             ocsp_fmt = GNUTLS_X509_FMT_DER;
+             ofile += 4;
+             }
 
-# ifdef SUPPORT_SRV_OCSP_STACK
-           if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
-                       state->x509_cred, gnutls_cert_index,
-                       server_ocsp_stapling_cb, ofile)))
+           if  ((rc = gnutls_certificate_set_ocsp_status_request_file2(
+                     state->x509_cred, CCS ofile, gnutls_cert_index,
+                     ocsp_fmt)) < 0)
              return tls_error_gnu(
-                     US"gnutls_certificate_set_ocsp_status_request_function2",
+                     US"gnutls_certificate_set_ocsp_status_request_file2",
                      rc, host, errstr);
+           DEBUG(D_tls)
+             debug_printf(" %d response%s loaded\n", rc, rc>1 ? "s":"");
+
+           /* Arrange callbacks for OCSP request observability */
+
+           gnutls_handshake_set_hook_function(state->session,
+             GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
+
 # else
-           if (cnt++ > 0)
+#  if defined(SUPPORT_SRV_OCSP_STACK)
+           if ((rc = gnutls_certificate_set_ocsp_status_request_function2(
+                        state->x509_cred, gnutls_cert_index,
+                        server_ocsp_stapling_cb, ofile)))
+               return tls_error_gnu(
+                     US"gnutls_certificate_set_ocsp_status_request_function2",
+                     rc, host, errstr);
+           else
+#  endif
              {
-             DEBUG(D_tls)
-               debug_printf("oops; multiple OCSP files not supported\n");
-             break;
+             if (cnt++ > 0)
+               {
+               DEBUG(D_tls)
+                 debug_printf("oops; multiple OCSP files not supported\n");
+               break;
+               }
+               gnutls_certificate_set_ocsp_status_request_function(
+                 state->x509_cred, server_ocsp_stapling_cb, ofile);
              }
-             gnutls_certificate_set_ocsp_status_request_function(
-               state->x509_cred, server_ocsp_stapling_cb, ofile);
-# endif
-
-           DEBUG(D_tls) debug_printf("OCSP response file = %s\n", ofile);
+# endif        /* SUPPORT_GNUTLS_EXT_RAW_PARSE */
            }
          else
            DEBUG(D_tls) debug_printf("ran out of OCSP response files in list\n");
-#endif
+         }
+#endif /* DISABLE_OCSP */
        }
     }
-  else
+  else /* client */
     {
     if (0 < (rc = tls_add_certfile(state, host,
                state->exp_tls_certificate, state->exp_tls_privatekey, errstr)))
@@ -1938,13 +2113,12 @@ uschar * dummy_errstr;
 rc = gnutls_server_name_get(session, sni_name, &data_len, &sni_type, 0);
 if (rc != GNUTLS_E_SUCCESS)
   {
-  DEBUG(D_tls) {
+  DEBUG(D_tls)
     if (rc == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
       debug_printf("TLS: no SNI presented in handshake.\n");
     else
       debug_printf("TLS failure: gnutls_server_name_get(): %s [%d]\n",
         gnutls_strerror(rc), rc);
-    }
   return 0;
   }
 
@@ -1957,7 +2131,7 @@ if (sni_type != GNUTLS_NAME_DNS)
 /* We now have a UTF-8 string in sni_name */
 old_pool = store_pool;
 store_pool = POOL_PERM;
-state->received_sni = string_copyn(US sni_name, data_len);
+state->received_sni = string_copy_taint(US sni_name, TRUE);
 store_pool = old_pool;
 
 /* We set this one now so that variable expansions below will work */
@@ -1984,7 +2158,7 @@ return 0;
 
 
 
-#ifndef DISABLE_OCSP
+#if !defined(DISABLE_OCSP)
 
 static int
 server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
@@ -2076,7 +2250,8 @@ post_handshake_debug(exim_gnutls_state_st * state)
 debug_printf("%s\n", gnutls_session_get_desc(state->session));
 #endif
 #ifdef SUPPORT_GNUTLS_KEYLOG
-# ifdef GNUTLS_TLS1_3
+
+# ifdef EXIM_HAVE_TLS1_3
 if (gnutls_protocol_get_version(state->session) < GNUTLS_TLS1_3)
 #else
 if (TRUE)
@@ -2096,7 +2271,8 @@ else
     " set environment variable SSLKEYLOGFILE to a filename writable by uid exim\n"
     " add SSLKEYLOGFILE to keep_environment in the exim config\n"
     " run exim as root\n"
-    " if using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n");
+    " if using sudo, add SSLKEYLOGFILE to env_keep in /etc/sudoers\n"
+    " (works for TLS1.2 also, and saves cut-paste into file)\n");
 #endif
 }
 
@@ -2134,7 +2310,7 @@ if (verify_check_host(&tls_resumption_hosts) == OK)
 
   /* Try to tell if we see a ticket request */
   gnutls_handshake_set_hook_function(state->session,
-    GNUTLS_HANDSHAKE_NEW_SESSION_TICKET, GNUTLS_HOOK_POST, tls_server_ticket_cb);
+    GNUTLS_HANDSHAKE_ANY, GNUTLS_HOOK_POST, tls_server_hook_cb);
   }
 }
 
@@ -2773,16 +2949,26 @@ if (request_ocsp)
     gnutls_datum_t stapling;
     gnutls_ocsp_resp_t resp;
     gnutls_datum_t printed;
-    if (  (rc= gnutls_ocsp_status_request_get(state->session, &stapling)) == 0
-       && (rc= gnutls_ocsp_resp_init(&resp)) == 0
-       && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
-       && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_FULL, &printed)) == 0
-       )
-      {
-      debug_printf("%.4096s", printed.data);
-      gnutls_free(printed.data);
-      }
-    else
+    unsigned idx = 0;
+
+    for (;
+# ifdef GNUTLS_OCSP_STATUS_REQUEST_GET2
+        (rc = gnutls_ocsp_status_request_get2(state->session, idx, &stapling)) == 0;
+#else
+        (rc = gnutls_ocsp_status_request_get(state->session, &stapling)) == 0;
+#endif
+        idx++)
+      if (  (rc= gnutls_ocsp_resp_init(&resp)) == 0
+        && (rc= gnutls_ocsp_resp_import(resp, &stapling)) == 0
+        && (rc= gnutls_ocsp_resp_print(resp, GNUTLS_OCSP_PRINT_COMPACT, &printed)) == 0
+        )
+       {
+       debug_printf("%.4096s", printed.data);
+       gnutls_free(printed.data);
+       }
+      else
+       (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr);
+    if (idx == 0 && rc)
       (void) tls_error_gnu(US"ocsp decode", rc, state->host, errstr);
     }