Handle certificate dir under GnuTLS, if recent enough

[exim.git] / src / src / tls-gnu.c

diff --git a/src/src/tls-gnu.c b/src/src/tls-gnu.c
index 266ab8909d1ce65263375c9632c43e1e4e9709e5..14cdd12d439724b3cddf426c6a1015bec290cb4f 100644 (file)
--- a/src/src/tls-gnu.c
+++ b/src/src/tls-gnu.c
@@ -47,6 +47,15 @@ require current GnuTLS, then we'll drop support for the ancient libraries).
 # warning "GnuTLS library version too old; define DISABLE_OCSP in Makefile"
 # define DISABLE_OCSP
 #endif
+#if GNUTLS_VERSION_NUMBER < 0x020a00 && defined(EXPERIMENTAL_TPDA)
+# warning "GnuTLS library version too old; TPDA tls:cert event unsupported"
+# undef EXPERIMENTAL_TPDA
+#endif
+#if GNUTLS_VERSION_NUMBER >= 0x030306
+# define SUPPORT_CA_DIR
+#else
+# undef  SUPPORT_CA_DIR
+#endif
 
 #ifndef DISABLE_OCSP
 # include <gnutls/ocsp.h>
@@ -115,6 +124,9 @@ typedef struct exim_gnutls_state {
 #ifdef EXPERIMENTAL_CERTNAMES
   uschar *exp_tls_verify_cert_hostnames;
 #endif
+#ifdef EXPERIMENTAL_TPDA
+  uschar *event_action;
+#endif
 
   tls_support *tlsp;   /* set in tls_init() */
 
@@ -132,6 +144,9 @@ static const exim_gnutls_state_st exim_gnutls_state_init = {
   NULL, NULL, NULL, NULL, NULL, NULL, NULL,
 #ifdef EXPERIMENTAL_CERTNAMES
                                             NULL,
+#endif
+#ifdef EXPERIMENTAL_TPDA
+                                            NULL,
 #endif
   NULL,
   NULL, 0, 0, 0, 0,
@@ -144,7 +159,9 @@ context we're currently dealing with" pointer and rely upon being
 single-threaded to keep from processing data on an inbound TLS connection while
 talking to another TLS connection for an outbound check.  This does mean that
 there's no way for heart-beats to be responded to, for the duration of the
-second connection. */
+second connection.
+XXX But see gnutls_session_get_ptr()
+*/
 
 static exim_gnutls_state_st state_server, state_client;
 
@@ -174,18 +191,18 @@ static BOOL exim_gnutls_base_init_done = FALSE;
 the library logging; a value less than 0 disables the calls to set up logging
 callbacks. */
 #ifndef EXIM_GNUTLS_LIBRARY_LOG_LEVEL
-#define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
+# define EXIM_GNUTLS_LIBRARY_LOG_LEVEL -1
 #endif
 
 #ifndef EXIM_CLIENT_DH_MIN_BITS
-#define EXIM_CLIENT_DH_MIN_BITS 1024
+# define EXIM_CLIENT_DH_MIN_BITS 1024
 #endif
 
 /* With GnuTLS 2.12.x+ we have gnutls_sec_param_to_pk_bits() with which we
 can ask for a bit-strength.  Without that, we stick to the constant we had
 before, for now. */
 #ifndef EXIM_SERVER_DH_BITS_PRE2_12
-#define EXIM_SERVER_DH_BITS_PRE2_12 1024
+# define EXIM_SERVER_DH_BITS_PRE2_12 1024
 #endif
 
 #define exim_gnutls_err_check(Label) do { \
@@ -872,6 +889,7 @@ if (Ustat(state->exp_tls_verify_certificates, &statbuf) < 0)
   return DEFER;
   }
 
+#ifndef SUPPORT_CA_DIR
 /* The test suite passes in /dev/null; we could check for that path explicitly,
 but who knows if someone has some weird FIFO which always dumps some certs, or
 other weirdness.  The thing we really want to check is that it's not a
@@ -887,6 +905,7 @@ if (S_ISDIR(statbuf.st_mode))
       state->exp_tls_verify_certificates);
   return DEFER;
   }
+#endif
 
 DEBUG(D_tls) debug_printf("verify certificates = %s size=" OFF_T_FMT "\n",
         state->exp_tls_verify_certificates, statbuf.st_size);
@@ -898,8 +917,18 @@ if (statbuf.st_size == 0)
   return OK;
   }
 
-cert_count = gnutls_certificate_set_x509_trust_file(state->x509_cred,
+cert_count =
+
+#ifdef SUPPORT_CA_DIR
+  (statbuf.st_mode & S_IFMT) == S_IFDIR
+  ?
+  gnutls_certificate_set_x509_trust_dir(state->x509_cred,
+    CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM)
+  :
+#endif
+  gnutls_certificate_set_x509_trust_file(state->x509_cred,
     CS state->exp_tls_verify_certificates, GNUTLS_X509_FMT_PEM);
+
 if (cert_count < 0)
   {
   rc = cert_count;
@@ -1512,6 +1541,52 @@ return 0;
 #endif
 
 
+#ifdef EXPERIMENTAL_TPDA
+/*
+We use this callback to get observability and detail-level control
+for an exim client TLS connection, raising a TPDA tls:cert event
+for each cert in the chain presented by the server.  Any event
+can deny verification.
+
+Return 0 for the handshake to continue or non-zero to terminate.
+*/
+
+static int
+client_verify_cb(gnutls_session_t session)
+{
+const gnutls_datum * cert_list;
+unsigned int cert_list_size = 0;
+gnutls_x509_crt_t crt;
+int rc;
+exim_gnutls_state_st * state = gnutls_session_get_ptr(session);
+
+cert_list = gnutls_certificate_get_peers(session, &cert_list_size);
+if (cert_list)
+  while (cert_list_size--)
+  {
+  rc = import_cert(&cert_list[cert_list_size], &crt);
+  if (rc != GNUTLS_E_SUCCESS)
+    {
+    DEBUG(D_tls) debug_printf("TLS: peer cert problem: depth %d: %s\n",
+      cert_list_size, gnutls_strerror(rc));
+    break;
+    }
+
+  state->tlsp->peercert = crt;
+  if (tpda_raise_event(state->event_action,
+             US"tls:cert", string_sprintf("%d", cert_list_size)) == DEFER)
+    {
+    log_write(0, LOG_MAIN,
+             "SSL verify denied by event-action: depth=%d", cert_list_size);
+    return 1;                     /* reject */
+    }
+  state->tlsp->peercert = NULL;
+  }
+
+return 0;
+}
+
+#endif
 
 
 
@@ -1694,7 +1769,7 @@ Arguments:
   fd                the fd of the connection
   host              connected host (for messages)
   addr              the first address (not used)
-  ob                smtp transport options
+  tb                transport (always smtp)
 
 Returns:            OK/DEFER/FAIL (because using common functions),
                     but for a client, DEFER and FAIL have the same meaning
@@ -1703,9 +1778,14 @@ Returns:            OK/DEFER/FAIL (because using common functions),
 int
 tls_client_start(int fd, host_item *host,
     address_item *addr ARG_UNUSED,
-    void *v_ob)
+    transport_instance *tb
+#ifdef EXPERIMENTAL_DANE
+    , dne_answer * unused_tlsa_dnsa
+#endif
+    )
 {
-smtp_transport_options_block *ob = v_ob;
+smtp_transport_options_block *ob =
+  (smtp_transport_options_block *)tb->options_block;
 int rc;
 const char *error;
 exim_gnutls_state_st *state = NULL;
@@ -1804,6 +1884,15 @@ if (request_ocsp)
   }
 #endif
 
+#ifdef EXPERIMENTAL_TPDA
+if (tb->tpda_event_action)
+  {
+  state->event_action = tb->tpda_event_action;
+  gnutls_session_set_ptr(state->session, state);
+  gnutls_certificate_set_verify_function(state->x509_cred, client_verify_cb);
+  }
+#endif
+
 gnutls_transport_set_ptr(state->session, (gnutls_transport_ptr)(long) fd);
 state->fd_in = fd;
 state->fd_out = fd;