OCSP observability: variables $tls_{in,out}_ocsp

and smtp transport option hosts_request_ocsp

10 files changed, 126 insertions, 46 deletions

diff --git a/src/src/expand.c b/src/src/expand.c
index 05b714a7f..de911db90 100644
--- a/src/src/expand.c
+++ b/src/src/expand.c
@@ -671,6 +671,7 @@ static var_entry var_table[] = {
   { "tls_in_bits",         vtype_int,         &tls_in.bits },
   { "tls_in_certificate_verified", vtype_int, &tls_in.certificate_verified },
   { "tls_in_cipher",       vtype_stringptr,   &tls_in.cipher },
+  { "tls_in_ocsp",         vtype_int,         &tls_in.ocsp },
   { "tls_in_ourcert",      vtype_cert,        &tls_in.ourcert },
   { "tls_in_peercert",     vtype_cert,        &tls_in.peercert },
   { "tls_in_peerdn",       vtype_stringptr,   &tls_in.peerdn },
@@ -680,6 +681,7 @@ static var_entry var_table[] = {
   { "tls_out_bits",        vtype_int,         &tls_out.bits },
   { "tls_out_certificate_verified", vtype_int,&tls_out.certificate_verified },
   { "tls_out_cipher",      vtype_stringptr,   &tls_out.cipher },
+  { "tls_out_ocsp",        vtype_int,         &tls_out.ocsp },
   { "tls_out_ourcert",     vtype_cert,        &tls_out.ourcert },
   { "tls_out_peercert",    vtype_cert,        &tls_out.peercert },
   { "tls_out_peerdn",      vtype_stringptr,   &tls_out.peerdn },
diff --git a/src/src/globals.c b/src/src/globals.c
index 7b591e42a..af2903525 100644
--- a/src/src/globals.c
+++ b/src/src/globals.c
@@ -109,7 +109,8 @@ tls_support tls_in = {
  NULL, /* tls_ourcert */
  NULL, /* tls_peercert */
  NULL, /* tls_peerdn */
- NULL  /* tls_sni */
+ NULL, /* tls_sni */
+ 0     /* tls_ocsp */
 };
 tls_support tls_out = {
  -1,   /* tls_active */
@@ -121,7 +122,8 @@ tls_support tls_out = {
  NULL, /* tls_ourcert */
  NULL, /* tls_peercert */
  NULL, /* tls_peerdn */
- NULL  /* tls_sni */
+ NULL, /* tls_sni */
+ 0     /* tls_ocsp */
 };
 
 
diff --git a/src/src/globals.h b/src/src/globals.h
index 584d1bd09..9a42fe27e 100644
--- a/src/src/globals.h
+++ b/src/src/globals.h
@@ -89,6 +89,12 @@ typedef struct {
   void	 *peercert;           /* Certificate of peer, binary */
   uschar *peerdn;             /* DN from peer */
   uschar *sni;                /* Server Name Indication */
+  enum {
+    OCSP_NOT_REQ=0,		/* not requested */
+    OCSP_NOT_RESP,		/* no response to request */
+    OCSP_NOT_VFY,		/* response not verified */
+    OCSP_VFIED			/* verified */
+    }     ocsp;		      /* Stapled OCSP status */
 } tls_support;
 extern tls_support tls_in;
 extern tls_support tls_out;
diff --git a/src/src/smtp_in.c b/src/src/smtp_in.c
index 6810d25e3..82a805a21 100644
--- a/src/src/smtp_in.c
+++ b/src/src/smtp_in.c
@@ -1820,6 +1820,7 @@ authenticated_by = NULL;
 tls_in.cipher = tls_in.peerdn = NULL;
 tls_in.ourcert = tls_in.peercert = NULL;
 tls_in.sni = NULL;
+tls_in.ocsp = OCSP_NOT_REQ;
 tls_advertised = FALSE;
 #endif
 
diff --git a/src/src/spool_in.c b/src/src/spool_in.c
index 2006e1b02..ba775bbce 100644
--- a/src/src/spool_in.c
+++ b/src/src/spool_in.c
@@ -289,6 +289,7 @@ tls_in.ourcert = NULL;
 tls_in.peercert = NULL;
 tls_in.peerdn = NULL;
 tls_in.sni = NULL;
+tls_in.ocsp = OCSP_NOT_REQ;
 #endif
 
 #ifdef WITH_CONTENT_SCAN
@@ -560,6 +561,8 @@ for (;;)
       tls_in.peerdn = string_unprinting(string_copy(big_buffer + 12));
     else if (Ustrncmp(p, "ls_sni", 6) == 0)
       tls_in.sni = string_unprinting(string_copy(big_buffer + 9));
+    else if (Ustrncmp(p, "ls_ocsp", 7) == 0)
+      tls_in.ocsp = big_buffer[10] - '0';
     break;
     #endif
 
diff --git a/src/src/spool_out.c b/src/src/spool_out.c
index 7bbd42df0..de81786b3 100644
--- a/src/src/spool_out.c
+++ b/src/src/spool_out.c
@@ -242,6 +242,7 @@ if (tls_in.ourcert)
   (void) tls_export_cert(big_buffer, big_buffer_size, tls_in.ourcert);
   fprintf(f, "-tls_ourcert %s\n", CS big_buffer);
   }
+if (tls_in.ocsp)	 fprintf(f, "-tls_ocsp %d\n",   tls_in.ocsp);
 #endif
 
 /* To complete the envelope, write out the tree of non-recipients, followed by
diff --git a/src/src/tls-gnu.c b/src/src/tls-gnu.c
index d0e1c35d7..b0b67d820 100644
--- a/src/src/tls-gnu.c
+++ b/src/src/tls-gnu.c
@@ -101,6 +101,7 @@ typedef struct exim_gnutls_state {
   uschar *exp_tls_verify_certificates;
   uschar *exp_tls_crl;
   uschar *exp_tls_require_ciphers;
+  uschar *exp_tls_ocsp_file;
 
   tls_support *tlsp;	/* set in tls_init() */
 
@@ -115,7 +116,7 @@ static const exim_gnutls_state_st exim_gnutls_state_init = {
   NULL, NULL, NULL, VERIFY_NONE, -1, -1, FALSE, FALSE, FALSE,
   NULL, NULL, NULL, NULL,
   NULL, NULL, NULL, NULL, NULL, NULL,
-  NULL, NULL, NULL, NULL, NULL, NULL,
+  NULL, NULL, NULL, NULL, NULL, NULL, NULL,
   NULL,
   NULL, 0, 0, 0, 0,
 };
@@ -203,6 +204,10 @@ static void exim_gnutls_logger_cb(int level, const char *message);
 
 static int exim_sni_handling_cb(gnutls_session_t session);
 
+#ifdef EXPERIMENTAL_OCSP
+static int server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
+  gnutls_datum_t * ocsp_response);
+#endif
 
 
 
@@ -791,18 +796,18 @@ if (  !host	/* server */
    && tls_ocsp_file
    )
   {
-  uschar * expanded;
-  int rc;
-
-  if (!expand_check(tls_ocsp_file, US"tls_ocsp_file", &expanded))
+  if (!expand_check(tls_ocsp_file, US"tls_ocsp_file",
+	&state->exp_tls_ocsp_file))
     return DEFER;
 
-  /* Lazy way; would like callback to emit debug on actual response */
+  /* 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.  */
+
+  gnutls_certificate_set_ocsp_status_request_function(state->x509_cred,
+    server_ocsp_stapling_cb, state->exp_tls_ocsp_file);
 
-  rc = gnutls_certificate_set_ocsp_status_request_file(state->x509_cred,
-      expanded, 0);
-  exim_gnutls_err_check(US"gnutls_certificate_set_ocsp_status_request_file");
-  DEBUG(D_tls) debug_printf("Set OCSP response file %s\n", expanded);
+  DEBUG(D_tls) debug_printf("Set OCSP response file %s\n", &state->exp_tls_ocsp_file);
   }
 #endif
 
@@ -1433,6 +1438,31 @@ return 0;
 
 
 
+#ifdef EXPERIMENTAL_OCSP
+
+static int
+server_ocsp_stapling_cb(gnutls_session_t session, void * ptr,
+  gnutls_datum_t * ocsp_response)
+{
+int ret;
+
+tls_in.ocsp = OCSP_NOT_RESP;
+if ((ret = gnutls_load_file(ptr, ocsp_response)) < 0)
+  {
+  DEBUG(D_tls) debug_printf("Failed to load ocsp stapling file %s\n",
+			      (char *)ptr);
+  return GNUTLS_E_NO_CERTIFICATE_STATUS;
+  }
+
+tls_in.ocsp = OCSP_NOT_VFY;
+return 0;
+}
+
+#endif
+
+
+
+
 
 /* ------------------------------------------------------------------------ */
 /* Exported functions */
@@ -1526,8 +1556,8 @@ if (!state->tlsp->on_connect)
 that the GnuTLS library doesn't. */
 
 gnutls_transport_set_ptr2(state->session,
-    (gnutls_transport_ptr)fileno(smtp_in),
-    (gnutls_transport_ptr)fileno(smtp_out));
+    (gnutls_transport_ptr)(long) fileno(smtp_in),
+    (gnutls_transport_ptr)(long) fileno(smtp_out));
 state->fd_in = fileno(smtp_in);
 state->fd_out = fileno(smtp_out);
 
@@ -1628,6 +1658,9 @@ exim_gnutls_state_st *state = NULL;
 #ifdef EXPERIMENTAL_OCSP
 BOOL require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
   NULL, host->name, host->address, NULL) == OK;
+BOOL request_ocsp = require_ocsp ? TRUE
+  : verify_check_this_host(&ob->hosts_request_ocsp,
+      NULL, host->name, host->address, NULL) == OK;
 #endif
 
 DEBUG(D_tls) debug_printf("initialising GnuTLS as a client on fd %d\n", fd);
@@ -1684,17 +1717,18 @@ else
   }
 
 #ifdef EXPERIMENTAL_OCSP	/* since GnuTLS 3.1.3 */
-if (require_ocsp)
+if (request_ocsp)
   {
   DEBUG(D_tls) debug_printf("TLS: will request OCSP stapling\n");
   if ((rc = gnutls_ocsp_status_request_enable_client(state->session,
 		    NULL, 0, NULL)) != OK)
     return tls_error(US"cert-status-req",
 		    gnutls_strerror(rc), state->host);
+  tls_out.ocsp = OCSP_NOT_RESP;
   }
 #endif
 
-gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr)fd);
+gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr)(long) fd);
 state->fd_in = fd;
 state->fd_out = fd;
 
@@ -1746,6 +1780,7 @@ if (require_ocsp)
   if (gnutls_ocsp_status_request_is_checked(state->session, 0) == 0)
     return tls_error(US"certificate status check failed", NULL, state->host);
   DEBUG(D_tls) debug_printf("Passed OCSP checking\n");
+  tls_out.ocsp = OCSP_VFIED;
   }
 #endif
 
diff --git a/src/src/tls-openssl.c b/src/src/tls-openssl.c
index 66fca7dbb..fd257f3c6 100644
--- a/src/src/tls-openssl.c
+++ b/src/src/tls-openssl.c
@@ -97,7 +97,8 @@ typedef struct tls_ext_ctx_cb {
       OCSP_RESPONSE *response;
     } server;
     struct {
-      X509_STORE    *verify_store;
+      X509_STORE    *verify_store;	/* non-null if status requested */
+      BOOL	    verify_required;
     } client;
   } u_ocsp;
 #endif
@@ -797,15 +798,18 @@ else
   DEBUG(D_tls) debug_printf("Received TLS status request (OCSP stapling); %s response.",
     cbinfo->u_ocsp.server.response ? "have" : "lack");
 
+tls_in.ocsp = OCSP_NOT_RESP;
 if (!cbinfo->u_ocsp.server.response)
   return SSL_TLSEXT_ERR_NOACK;
 
 response_der = NULL;
-response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response, &response_der);
+response_der_len = i2d_OCSP_RESPONSE(cbinfo->u_ocsp.server.response,
+		      &response_der);
 if (response_der_len <= 0)
   return SSL_TLSEXT_ERR_NOACK;
 
 SSL_set_tlsext_status_ocsp_resp(server_ssl, response_der, response_der_len);
+tls_in.ocsp = OCSP_VFIED;
 return SSL_TLSEXT_ERR_OK;
 }
 
@@ -832,12 +836,15 @@ DEBUG(D_tls) debug_printf("Received TLS status response (OCSP stapling):");
 len = SSL_get_tlsext_status_ocsp_resp(s, &p);
 if(!p)
  {
-  if (log_extra_selector & LX_tls_cipher)
-    log_write(0, LOG_MAIN, "Received TLS status response, null content");
+  /* Expect this when we requested ocsp but got none */
+  if (  cbinfo->u_ocsp.client.verify_required
+     && log_extra_selector & LX_tls_cipher)
+    log_write(0, LOG_MAIN, "Received TLS status callback, null content");
   else
     DEBUG(D_tls) debug_printf(" null\n");
-  return 0;	/* This is the fail case for require-ocsp; none from server */
+  return cbinfo->u_ocsp.client.verify_required ? 0 : 1;
  }
+tls_out.ocsp = OCSP_NOT_VFY;
 if(!(rsp = d2i_OCSP_RESPONSE(NULL, &p, len)))
  {
   if (log_extra_selector & LX_tls_cipher)
@@ -878,11 +885,12 @@ if(!(bs = OCSP_response_get1_basic(rsp)))
     /* Use the chain that verified the server cert to verify the stapled info */
     /* DEBUG(D_tls) x509_store_dump_cert_s_names(cbinfo->u_ocsp.client.verify_store); */
 
-    if ((i = OCSP_basic_verify(bs, NULL, cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
+    if ((i = OCSP_basic_verify(bs, NULL,
+	      cbinfo->u_ocsp.client.verify_store, 0)) <= 0)
       {
       BIO_printf(bp, "OCSP response verify failure\n");
       ERR_print_errors(bp);
-      i = 0;
+      i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
       goto out;
       }
 
@@ -894,39 +902,48 @@ if(!(bs = OCSP_response_get1_basic(rsp)))
 
       if (sk_OCSP_SINGLERESP_num(sresp) != 1)
         {
-        log_write(0, LOG_MAIN, "OCSP stapling with multiple responses not handled");
+        log_write(0, LOG_MAIN, "OCSP stapling "
+	    "with multiple responses not handled");
+	i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
         goto out;
         }
       single = OCSP_resp_get0(bs, 0);
-      status = OCSP_single_get0_status(single, &reason, &rev, &thisupd, &nextupd);
+      status = OCSP_single_get0_status(single, &reason, &rev,
+		  &thisupd, &nextupd);
       }
 
-    i = 0;
     DEBUG(D_tls) time_print(bp, "This OCSP Update", thisupd);
     DEBUG(D_tls) if(nextupd) time_print(bp, "Next OCSP Update", nextupd);
-    if (!OCSP_check_validity(thisupd, nextupd, EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
+    if (!OCSP_check_validity(thisupd, nextupd,
+	  EXIM_OCSP_SKEW_SECONDS, EXIM_OCSP_MAX_AGE))
       {
       DEBUG(D_tls) ERR_print_errors(bp);
       log_write(0, LOG_MAIN, "Server OSCP dates invalid");
-      goto out;
+      i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
       }
-
-    DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n", OCSP_cert_status_str(status));
-    switch(status)
+    else
       {
-      case V_OCSP_CERTSTATUS_GOOD:
-        i = 1;
-        break;
-      case V_OCSP_CERTSTATUS_REVOKED:
-        log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
-            reason != -1 ? "; reason: " : "", reason != -1 ? OCSP_crl_reason_str(reason) : "");
-        DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
-        i = 0;
-        break;
-      default:
-        log_write(0, LOG_MAIN, "Server certificate status unknown, in OCSP stapling");
-        i = 0;
-        break;
+      DEBUG(D_tls) BIO_printf(bp, "Certificate status: %s\n",
+		    OCSP_cert_status_str(status));
+      switch(status)
+	{
+	case V_OCSP_CERTSTATUS_GOOD:
+	  i = 1;
+	  tls_out.ocsp = OCSP_VFIED;
+	  break;
+	case V_OCSP_CERTSTATUS_REVOKED:
+	  log_write(0, LOG_MAIN, "Server certificate revoked%s%s",
+	      reason != -1 ? "; reason: " : "",
+	      reason != -1 ? OCSP_crl_reason_str(reason) : "");
+	  DEBUG(D_tls) time_print(bp, "Revocation Time", rev);
+	  i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
+	  break;
+	default:
+	  log_write(0, LOG_MAIN,
+	      "Server certificate status unknown, in OCSP stapling");
+	  i = cbinfo->u_ocsp.client.verify_required ? 0 : 1;
+	  break;
+	}
       }
   out:
     BIO_free(bp);
@@ -1497,12 +1514,15 @@ static uschar cipherbuf[256];
 #ifdef EXPERIMENTAL_OCSP
 BOOL require_ocsp = verify_check_this_host(&ob->hosts_require_ocsp,
   NULL, host->name, host->address, NULL) == OK;
+BOOL request_ocsp = require_ocsp ? TRUE
+  : verify_check_this_host(&ob->hosts_request_ocsp,
+      NULL, host->name, host->address, NULL) == OK;
 #endif
 
 rc = tls_init(&client_ctx, host, NULL,
     ob->tls_certificate, ob->tls_privatekey,
 #ifdef EXPERIMENTAL_OCSP
-    require_ocsp ? US"" : NULL,
+    (void *)(long)request_ocsp,
 #endif
     addr, &client_static_cbinfo);
 if (rc != OK) return rc;
@@ -1578,8 +1598,12 @@ if (ob->tls_sni)
 #ifdef EXPERIMENTAL_OCSP
 /* Request certificate status at connection-time.  If the server
 does OCSP stapling we will get the callback (set in tls_init()) */
-if (require_ocsp)
+if (request_ocsp)
+  {
   SSL_set_tlsext_status_type(client_ssl, TLSEXT_STATUSTYPE_ocsp);
+  client_static_cbinfo->u_ocsp.client.verify_required = require_ocsp;
+  tls_out.ocsp = OCSP_NOT_RESP;
+  }
 #endif
 
 /* There doesn't seem to be a built-in timeout on connection. */
diff --git a/src/src/transports/smtp.c b/src/src/transports/smtp.c
index 7223f9c89..9089d90c1 100644
--- a/src/src/transports/smtp.c
+++ b/src/src/transports/smtp.c
@@ -102,6 +102,10 @@ optionlist smtp_transport_options[] = {
       (void *)offsetof(smtp_transport_options_block, hosts_override) },
   { "hosts_randomize",      opt_bool,
       (void *)offsetof(smtp_transport_options_block, hosts_randomize) },
+#if defined(SUPPORT_TLS) && defined(EXPERIMENTAL_OCSP)
+  { "hosts_request_ocsp",   opt_stringptr,
+      (void *)offsetof(smtp_transport_options_block, hosts_request_ocsp) },
+#endif
   { "hosts_require_auth",   opt_stringptr,
       (void *)offsetof(smtp_transport_options_block, hosts_require_auth) },
 #ifdef SUPPORT_TLS
@@ -196,6 +200,7 @@ smtp_transport_options_block smtp_transport_option_defaults = {
   NULL,                /* hosts_try_prdr */
 #endif
 #ifdef EXPERIMENTAL_OCSP
+  US"*",               /* hosts_request_ocsp */
   NULL,                /* hosts_require_ocsp */
 #endif
   NULL,                /* hosts_require_tls */
diff --git a/src/src/transports/smtp.h b/src/src/transports/smtp.h
index 6912ad83e..900542564 100644
--- a/src/src/transports/smtp.h
+++ b/src/src/transports/smtp.h
@@ -25,6 +25,7 @@ typedef struct {
   uschar *hosts_try_prdr;
 #endif
 #ifdef EXPERIMENTAL_OCSP
+  uschar *hosts_request_ocsp;
   uschar *hosts_require_ocsp;
 #endif
   uschar *hosts_require_tls;