features.h; tls_validate_require_cipher: log flag & tests

[users/heiko/exim.git] / src / README.UPDATING

diff --git a/src/README.UPDATING b/src/README.UPDATING
index 62d1d2745010e9dc5f385480e1ce7643b1752bbc..e685b8ec3d4aed6544f8c3067d85fb2c7d6805dc 100644 (file)
--- a/src/README.UPDATING
+++ b/src/README.UPDATING
@@ -66,6 +66,11 @@ Exim version 4.80
    security for compatibility.  Exim is now defaulting to higher security and
    rewarding more modern clients.
 
+   If the option tls_dhparams is set and the parameters loaded from the file
+   have a bit-count greater than the new option tls_dh_max_bits, then the file
+   will now be ignored.  If this affects you, raise the tls_dh_max_bits limit.
+   We suspect that most folks are using dated defaults and will not be affected.
+
  * Ldap lookups returning multi-valued attributes now separate the attributes
    with only a comma, not a comma-space sequence.  Also, an actual comma within
    a returned attribute is doubled.  This makes it possible to parse the
@@ -80,16 +85,18 @@ Exim version 4.80
    new option, you can safely force it off before upgrading, to decouple
    configuration changes from the binary upgrade while remaining RFC compliant.
 
- * The GnuTLS support has been mostly rewritten, to use 2.12.x APIs.  As part
-   of this, these three options are no longer supported:
+ * The GnuTLS support has been mostly rewritten, to use APIs which don't cause
+   deprecation warnings in GnuTLS 2.12.x.  As part of this, these three options
+   are no longer supported:
 
      gnutls_require_kx
      gnutls_require_mac
      gnutls_require_protocols
 
-   Their functionality is entirely subsumed into tls_require_ciphers, which is
-   no longer parsed apart by Exim but is instead given to
-   gnutls_priority_init(3), which is no longer an Exim list.  See:
+   Their functionality is entirely subsumed into tls_require_ciphers.  In turn,
+   tls_require_ciphers is no longer an Exim list and is not parsed by Exim, but
+   is instead given to gnutls_priority_init(3), which expects a priority string;
+   this behaviour is much closer to the OpenSSL behaviour.  See:
 
      http://www.gnu.org/software/gnutls/manual/html_node/Priority-Strings.html
 
@@ -109,6 +116,25 @@ Exim version 4.80
    support for SNI and other features more readily.  We regret that it wasn't
    feasible to retain the three dropped options.
 
+ * If built with TLS support, then Exim will now validate the value of
+   the main section tls_require_ciphers option at start-up.  Before, this
+   would cause a STARTTLS 4xx failure, now it causes a failure to start.
+   Running with a broken configuration which causes failures that may only
+   be left in the logs has been traded off for something more visible.  This
+   change makes an existing problem more prominent, but we do not believe
+   anyone would deliberately be running with an invalid tls_require_ciphers
+   option.
+
+   This also means that library linkage issues caused by conflicts of some
+   kind might take out the main daemon, not just the delivery or receiving
+   process.  Conceivably some folks might prefer to continue delivering
+   mail plaintext when their binary is broken in this way, if there is a
+   server that is a candidate to receive such mails that does not advertise
+   STARTTLS.  Note that Exim is typically a setuid root binary and given
+   broken linkage problems that cause segfaults, we feel it is safer to
+   fail completely.  (The check is not done as root, to ensure that problems
+   here are not made worse by the check).
+
 
 Exim version 4.77
 -----------------