GnuTLS: fix the advertising of acceptable certs by the server. Bug 2389

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

diff --git a/src/README.UPDATING b/src/README.UPDATING
index a91794d6cd35bf65e500beddcfa26b1e21e70793..b619f5e03851ff31f94867e721674ed9436ad2a6 100644 (file)
--- a/src/README.UPDATING
+++ b/src/README.UPDATING
@@ -26,11 +26,104 @@ The rest of this document contains information about changes in 4.xx releases
 that might affect a running system.
 
 
 that might affect a running system.
 
 

+Exim version 4.92
+-----------------
+
+ * Exim used to manually follow CNAME chains, to a limited depth.  In this
+   day-and-age we expect the resolver to be doing this for us, so the loop
+   is limited to one retry unless the (new) config option dns_cname_loops
+   is changed.
+
+Exim version 4.91
+-----------------
+
+ * DANE and SPF have been promoted from Experimental to Supported status, thus
+   the options to enable them in Local/Makefile have been renamed.
+   See current src/EDITME for full details, including changes in dependencies,
+   but loosely: replace EXPERIMENTAL_SPF with SUPPORT_SPF and replace
+   EXPERIMENTAL_DANE with SUPPORT_DANE.
+
+ * Ancient ClamAV stream support, long deprecated by ClamAV, has been removed;
+   if you were building with WITH_OLD_CLAMAV_STREAM enabled then your problems
+   have marginally increased.
+
+ * A number of logging changes; if relying upon the previous DKIM additional
+   log-line, explicit log_selector configuration is needed to keep it.
+
+ * Other incompatible changes in EXPERIMENTAL_* features, read NewStuff and
+   ChangeLog carefully if relying upon an experimental feature such as DMARC.
+   Note that this includes changes to SPF as it was promoted into Supported.
+
+
+Exim version 4.89
+-----------------
+
+ * SMTP CHUNKING in Exim 4.88 did not ensure that received mails had a final
+   newline; attempts to deliver such messages onwards to non-chunking hosts
+   would probably hang, as Exim does not insert the newline before a ".".
+   In 4.89, the newline is added upon receipt.  For already-received messages
+   in your queue, try util/chunking_fixqueue_finalnewlines.pl
+   to walk the queue, fixing any affected messages.  Note that because a
+   delivery attempt will be hanging, attempts to lock the messages for fixing
+   them will stall; stopping all queue-runners temporarily is recommended.
+
+ * OpenSSL: oldest supported release series is now 1.0.2, which is the oldest
+   supported by the OpenSSL project.  If you can build Exim with an older
+   release series, congratulations.  If you can't, then upgrade.
+   The file doc/openssl.txt contains instructions for installing a current
+   OpenSSL outside the system library paths and building Exim to use it.
+
+ * FreeBSD: we now always use the system iconv in libc, as all versions of
+   FreeBSD supported by the FreeBSD project provide this functionality.
+
+
+Exim version 4.88
+-----------------
+
+ * The "demime" ACL condition, deprecated for the past 10 years, has
+   now been removed.
+
+ * Old GnuTLS configuration options "gnutls_require_kx", "gnutls_require_mac",
+   and "gnutls_require_protocols" have now been removed.  (Inoperative from
+   4.80, per below; logging warnings since 4.83, again per below).
+
+
+Exim version 4.83
+-----------------
+
+ * SPF condition results renamed "permerror" and "temperror".  The old
+   names are still accepted for back-compatibility, for this release.
+
+ * TLS details are now logged on rejects, subject to log selectors.
+
+ * Items in headers_remove lists must now have any embedded list-separators
+   doubled.
+
+ * Attempted use of the deprecated options "gnutls_require_kx" et. al.
+   now result in logged warning.
+
+
+Exim version 4.82
+-----------------
+
+ * New option gnutls_allow_auto_pkcs11 defaults false; if you have GnuTLS 2.12.0
+   or later and do want PKCS11 modules to be autoloaded, then set this option.
+
+ * A per-transport wait-<name> database is no longer updated if the transport
+   sets "connection_max_messages" to 1, as it can not be used and causes
+   unnecessary serialisation and load.  External tools tracking the state of
+   Exim by the hints databases may need modification to take this into account.
+
+ * The av_scanner option can now accept multiple clamd TCP targets, all other
+   setting limitations remain.
+
+

 Exim version 4.80
 -----------------
 
  * BEWARE backwards-incompatible changes in SSL libraries, thus the version
    bump.  See points below for details.
 Exim version 4.80
 -----------------
 
  * BEWARE backwards-incompatible changes in SSL libraries, thus the version
    bump.  See points below for details.

+   Also an LDAP data returned format change.

 
  * The value of $tls_peerdn is now print-escaped when written to the spool file
    in a -tls_peerdn line, and unescaped when read back in.  We received reports
 
  * The value of $tls_peerdn is now print-escaped when written to the spool file
    in a -tls_peerdn line, and unescaped when read back in.  We received reports


@@ -40,7 +133,13 @@ Exim version 4.80
    upgrading, then lock the message, replace the new-lines that should be part
    of the -tls_peerdn line with the two-character sequence \n and then unlock
    the message.  No tool has been provided as we believe this is a rare
    upgrading, then lock the message, replace the new-lines that should be part
    of the -tls_peerdn line with the two-character sequence \n and then unlock
    the message.  No tool has been provided as we believe this is a rare

-   occurence.
+   occurrence.
+
+ * For OpenSSL, SSLv2 is now disabled by default.  (GnuTLS does not support
+   SSLv2).  RFC 6176 prohibits SSLv2 and some informal surveys suggest no
+   actual usage.  You can re-enable with the "openssl_options" Exim option,
+   in the main configuration section.  Note that supporting SSLv2 exposes
+   you to ciphersuite downgrade attacks.

 
  * With OpenSSL 1.0.1+, Exim now supports TLS 1.1 and TLS 1.2.  If built
    against 1.0.1a then you will get a warning message and the
 
  * With OpenSSL 1.0.1+, Exim now supports TLS 1.1 and TLS 1.2.  If built
    against 1.0.1a then you will get a warning message and the


@@ -51,8 +150,9 @@ Exim version 4.80
    "openssl_options" gains "no_tlsv1_1", "no_tlsv1_2" and "no_compression".
 
    COMPATIBILITY WARNING: The default value of "openssl_options" is no longer
    "openssl_options" gains "no_tlsv1_1", "no_tlsv1_2" and "no_compression".
 
    COMPATIBILITY WARNING: The default value of "openssl_options" is no longer

-   "+dont_insert_empty_fragments".  We default to unset.  That old default was
-   grandfathered in from before openssl_options became a configuration option.
+   "+dont_insert_empty_fragments".  We default to "+no_sslv2".
+   That old default was grandfathered in from before openssl_options became a
+   configuration option.

    Empty fragments are inserted by default through TLS1.0, to partially defend
    against certain attacks; TLS1.1+ change the protocol so that this is not
    needed.  The DIEF SSL option was required for some old releases of mail
    Empty fragments are inserted by default through TLS1.0, to partially defend
    against certain attacks; TLS1.1+ change the protocol so that this is not
    needed.  The DIEF SSL option was required for some old releases of mail


@@ -66,12 +166,23 @@ Exim version 4.80
    security for compatibility.  Exim is now defaulting to higher security and
    rewarding more modern clients.
 
    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
    attribute as a comma-separated list.  Note the distinction from multiple
    attributes being returned, where each one is a name=value pair.
 
  * 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
    attribute as a comma-separated list.  Note the distinction from multiple
    attributes being returned, where each one is a name=value pair.
 

+   If you are currently splitting the results from LDAP upon a comma, then you
+   should check carefully to see if adjustments are needed.
+
+   This change lets cautious folks distinguish "comma used as separator for
+   joining values" from "comma inside the data".
+

  * accept_8bitmime now defaults on, which is not RFC compliant but is better
    suited to today's Internet.  See http://cr.yp.to/smtp/8bitmime.html for a
    sane rationale.  Those who wish to be strictly RFC compliant, or know that
  * accept_8bitmime now defaults on, which is not RFC compliant but is better
    suited to today's Internet.  See http://cr.yp.to/smtp/8bitmime.html for a
    sane rationale.  Those who wish to be strictly RFC compliant, or know that


@@ -80,18 +191,20 @@ 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.
 
    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
 
 
      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
+     http://www.gnutls.org/manual/html_node/Priority-Strings.html

 
    for fuller documentation of the strings parsed.  The three gnutls_require_*
    options are still parsed by Exim and, for this release, silently ignored.
 
    for fuller documentation of the strings parsed.  The three gnutls_require_*
    options are still parsed by Exim and, for this release, silently ignored.


@@ -109,6 +222,40 @@ 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.
 
    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).
+
+ * The "tls_dhparam" option has been updated, so that it can now specify a
+   path or an identifier for a standard DH prime from one of a few RFCs.
+   The default for OpenSSL is no longer to not use DH but instead to use
+   one of these standard primes.  The default for GnuTLS is no longer to use
+   a file in the spool directory, but to use that same standard prime.
+   The option is now used by GnuTLS too.  If it points to a path, then
+   GnuTLS will use that path, instead of a file in the spool directory;
+   GnuTLS will attempt to create it if it does not exist.
+
+   To preserve the previous behaviour of generating files in the spool
+   directory, set "tls_dhparam = historic".  Since prior releases of Exim
+   ignored tls_dhparam when using GnuTLS, this can safely be done before
+   the upgrade.
+
+

 
 Exim version 4.77
 -----------------
 
 Exim version 4.77
 -----------------


@@ -119,6 +266,9 @@ Exim version 4.77
    problem.  Prior to this release, supported values were "TLS1" and "SSL3",
    so you should be able to update configuration prior to update.
 
    problem.  Prior to this release, supported values were "TLS1" and "SSL3",
    so you should be able to update configuration prior to update.
 

+    [nb: gnutls_require_protocols removed in Exim 4.80, instead use
+         tls_require_ciphers to provide a priority string; see notes above]
+

  * The match_<type>{string1}{string2} expansion conditions no longer subject
    string2 to string expansion, unless Exim was built with the new
    "EXPAND_LISTMATCH_RHS" option.  Too many people have inadvertently created
  * The match_<type>{string1}{string2} expansion conditions no longer subject
    string2 to string expansion, unless Exim was built with the new
    "EXPAND_LISTMATCH_RHS" option.  Too many people have inadvertently created


@@ -196,7 +346,7 @@ Exim version 4.70
 -----------------
 
 1. Experimental Yahoo! Domainkeys support has been dropped in this release.
 -----------------
 
 1. Experimental Yahoo! Domainkeys support has been dropped in this release.

-It has been superceded by a native implementation of its successor DKIM.
+It has been superseded by a native implementation of its successor DKIM.

 
 2. Up to version 4.69, Exim came with an embedded version of the PCRE library.
 As of 4.70, this is no longer the case. To compile Exim, you will need PCRE
 
 2. Up to version 4.69, Exim came with an embedded version of the PCRE library.
 As of 4.70, this is no longer the case. To compile Exim, you will need PCRE


@@ -442,7 +592,7 @@ Version 4.23
 3. Version 4.23 saves the contents of the ACL variables with the message, so
    that they can be used later. If one of these variables contains a newline,
    there will be a newline character in the spool that will not be interpreted
 3. Version 4.23 saves the contents of the ACL variables with the message, so
    that they can be used later. If one of these variables contains a newline,
    there will be a newline character in the spool that will not be interpreted

-   correctely by a previous version of Exim. (Exim ignores keyed spool file
+   correctly by a previous version of Exim. (Exim ignores keyed spool file

    items that it doesn't understand - precisely for this kind of problem - but
    it expects them all to be on one line.)
 
    items that it doesn't understand - precisely for this kind of problem - but
    it expects them all to be on one line.)