Revert "GnuTLS: lose DH-param setup, for recent library versions where no longer...

It seems the documentation lies and the params really are needed.

This reverts commits 041bf37266, 49132a3bb5c6

diff --git a/doc/doc-docbook/spec.xfpt b/doc/doc-docbook/spec.xfpt
index dcda2ff798f9d55334358050368dc5ec2f62d354..a8cd63b192a5c38fe7ebac7be55cbf11f997c694 100644 (file)
--- a/doc/doc-docbook/spec.xfpt
+++ b/doc/doc-docbook/spec.xfpt
@@ -18429,12 +18429,7 @@ larger prime than requested.
 The value of this option is expanded and indicates the source of DH parameters
 to be used by Exim.
 
 The value of this option is expanded and indicates the source of DH parameters
 to be used by Exim.
 

-This option is ignored for GnuTLS version 3.6.0 and later.
-The library manages parameter negotiation internally.
-
-&*Note: The Exim Maintainers strongly recommend,
-for other TLS library versions,
-using a filename with site-generated
+&*Note: The Exim Maintainers strongly recommend using a filename with site-generated

 local DH parameters*&, which has been supported across all versions of Exim.  The
 other specific constants available are a fallback so that even when
 "unconfigured", Exim can offer Perfect Forward Secrecy in older ciphersuites in TLS.
 local DH parameters*&, which has been supported across all versions of Exim.  The
 other specific constants available are a fallback so that even when
 "unconfigured", Exim can offer Perfect Forward Secrecy in older ciphersuites in TLS.

diff --git a/src/src/tls-gnu.c b/src/src/tls-gnu.c
index aea1bd8b216650baa7ea4a83a3af96dda32fb79c..7b67bb7933ef94f013d1302a5d4e67bf098a5503 100644 (file)
--- a/src/src/tls-gnu.c
+++ b/src/src/tls-gnu.c
@@ -89,9 +89,6 @@ 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 >= 0x030506 && !defined(DISABLE_OCSP)
 # define SUPPORT_SRV_OCSP_STACK
 #endif

-#if GNUTLS_VERSION_NUMBER >= 0x030600
-# define GNUTLS_AUTO_DHPARAMS
-#endif

 #if GNUTLS_VERSION_NUMBER >= 0x030603
 # define EXIM_HAVE_TLS1_3
 # define SUPPORT_GNUTLS_EXT_RAW_PARSE
 #if GNUTLS_VERSION_NUMBER >= 0x030603
 # define EXIM_HAVE_TLS1_3
 # define SUPPORT_GNUTLS_EXT_RAW_PARSE


@@ -265,13 +262,11 @@ static exim_gnutls_state_st state_server = {
   .fd_out =            -1,
 };
 
   .fd_out =            -1,
 };
 

-#ifndef GNUTLS_AUTO_DHPARAMS

 /* dh_params are initialised once within the lifetime of a process using TLS;
 if we used TLS in a long-lived daemon, we'd have to reconsider this.  But we
 don't want to repeat this. */
 
 static gnutls_dh_params_t dh_server_params = NULL;
 /* dh_params are initialised once within the lifetime of a process using TLS;
 if we used TLS in a long-lived daemon, we'd have to reconsider this.  But we
 don't want to repeat this. */
 
 static gnutls_dh_params_t dh_server_params = NULL;

-#endif

 
 static int ssl_session_timeout = 7200; /* Two hours */
 
 
 static int ssl_session_timeout = 7200; /* Two hours */
 


@@ -688,7 +683,6 @@ if (!state->host)
 
 
 
 
 
 

-#ifndef GNUTLS_AUTO_DHPARAMS

 /*************************************************
 *            Setup up DH parameters              *
 *************************************************/
 /*************************************************
 *            Setup up DH parameters              *
 *************************************************/


@@ -711,7 +705,7 @@ init_server_dh(uschar ** errstr)
 {
 int fd, rc;
 unsigned int dh_bits;
 {
 int fd, rc;
 unsigned int dh_bits;

-gnutls_datum_t m = {.data = NULL, .size = 0};
+gnutls_datum_t m;

 uschar filename_buf[PATH_MAX];
 uschar *filename = NULL;
 size_t sz;
 uschar filename_buf[PATH_MAX];
 uschar *filename = NULL;
 size_t sz;


@@ -724,6 +718,9 @@ DEBUG(D_tls) debug_printf("Initialising GnuTLS server params\n");
 if ((rc = gnutls_dh_params_init(&dh_server_params)))
   return tls_error_gnu(NULL, US"gnutls_dh_params_init", rc, errstr);
 
 if ((rc = gnutls_dh_params_init(&dh_server_params)))
   return tls_error_gnu(NULL, US"gnutls_dh_params_init", rc, errstr);
 

+m.data = NULL;
+m.size = 0;
+

 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
   return DEFER;
 
 if (!expand_check(tls_dhparam, US"tls_dhparam", &exp_tls_dhparam, errstr))
   return DEFER;
 


@@ -873,12 +870,14 @@ if (rc < 0)
     return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr);
   (void)exim_chown(temp_fn, exim_uid, exim_gid);   /* Probably not necessary */
 
     return tls_error_sys(US"Unable to open temp file", errno, NULL, errstr);
   (void)exim_chown(temp_fn, exim_uid, exim_gid);   /* Probably not necessary */
 

-  /* GnuTLS overshoots!  If we ask for 2236, we might get 2237 or more.  But
-  there's no way to ask GnuTLS how many bits there really are.  We can ask
-  how many bits were used in a TLS session, but that's it!  The prime itself
-  is hidden behind too much abstraction.  So we ask for less, and proceed on
-  a wing and a prayer.  First attempt, subtracted 3 for 2233 and got 2240.  */
-
+  /* GnuTLS overshoots!
+   * If we ask for 2236, we might get 2237 or more.
+   * But there's no way to ask GnuTLS how many bits there really are.
+   * We can ask how many bits were used in a TLS session, but that's it!
+   * The prime itself is hidden behind too much abstraction.
+   * So we ask for less, and proceed on a wing and a prayer.
+   * First attempt, subtracted 3 for 2233 and got 2240.
+   */

   if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
     {
     dh_bits_gen = dh_bits - 10;
   if (dh_bits >= EXIM_CLIENT_DH_MIN_BITS + 10)
     {
     dh_bits_gen = dh_bits - 10;


@@ -941,7 +940,6 @@ if (rc < 0)
 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
 return OK;
 }
 DEBUG(D_tls) debug_printf("initialized server D-H parameters\n");
 return OK;
 }

-#endif

 
 
 
 
 
 


@@ -1952,7 +1950,6 @@ tls_set_remaining_x509(exim_gnutls_state_st *state, uschar ** errstr)
 int rc;
 const host_item *host = state->host;  /* macro should be reconsidered? */
 
 int rc;
 const host_item *host = state->host;  /* macro should be reconsidered? */
 

-#ifndef GNUTLS_AUTO_DHPARAMS

 /* Create D-H parameters, or read them from the cache file. This function does
 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
 client-side params. */
 /* Create D-H parameters, or read them from the cache file. This function does
 its own SMTP error messaging. This only happens for the server, TLS D-H ignores
 client-side params. */


@@ -1962,13 +1959,10 @@ if (!state->host)
   if (!dh_server_params)
     if ((rc = init_server_dh(errstr)) != OK) return rc;
 
   if (!dh_server_params)
     if ((rc = init_server_dh(errstr)) != OK) return rc;
 

-  /* Unnecessary & discouraged with 3.6.0 or later */
+  /* Unnecessary & discouraged with 3.6.0 or later, according to docs.  But without it,
+  no DHE- ciphers are advertised. */

   gnutls_certificate_set_dh_params(state->lib_state.x509_cred, dh_server_params);
   }
   gnutls_certificate_set_dh_params(state->lib_state.x509_cred, dh_server_params);
   }

-#else
-DEBUG(D_tls) if (tls_dhparam)
-  debug_printf("Ignoring tls_dhparam (recent version GnuTLS)\n");
-#endif

 
 /* Link the credentials to the session. */
 
 
 /* Link the credentials to the session. */