X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/a7ee59558e5cf70be000dbf421d69fb6c8c171c4..exim-4_80_RC2:/src/README.UPDATING diff --git a/src/README.UPDATING b/src/README.UPDATING index 3ee3035e9..7ce35dff8 100644 --- a/src/README.UPDATING +++ b/src/README.UPDATING @@ -26,6 +26,92 @@ The rest of this document contains information about changes in 4.xx releases that might affect a running system. +Exim version 4.80 +----------------- + + * BEWARE backwards-incompatible changes in SSL libraries, thus the version + bump. See points below for details. + + * 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 + of values with embedded newlines, which caused spool file corruption. + + If you have a corrupt spool file and you wish to recover the contents after + 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. + + * 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 + "openssl_options" value will not parse "no_tlsv1_1": the value changes + incompatibly between 1.0.1a and 1.0.1b, because the value chosen for 1.0.1a + is infelicitous. We advise avoiding 1.0.1a. + + "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. + 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 + clients which did not gracefully handle the empty fragments, and was + initially set in Exim release 4.31 (see ChangeLog, item 37). + + If you still have affected mail-clients, and you see SSL protocol failures + with this release of Exim, set: + openssl_options = +dont_insert_empty_fragments + in the main section of your Exim configuration file. You're trading off + security for compatibility. Exim is now defaulting to higher security and + rewarding more modern clients. + + * 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. + + * 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 + they need to talk to servers that are not 8-bit-clean, now need to take + explicit configuration action to default this option off. This is not a + 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 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. 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 + + for fuller documentation of the strings parsed. The three gnutls_require_* + options are still parsed by Exim and, for this release, silently ignored. + A future release will add warnings, before a later still release removes + parsing entirely and the presence of the options will be a configuration + error. + + Note that by default, GnuTLS will not accept RSA-MD5 signatures in chains. + A tls_require_ciphers value of NORMAL:%VERIFY_ALLOW_SIGN_RSA_MD5 may + re-enable support, but this is not supported by the Exim maintainers. + Our test suite no longer includes MD5-based certificates. + + This rewrite means that Exim will continue to build against GnuTLS in the + future, brings Exim closer to other GnuTLS applications and lets us add + support for SNI and other features more readily. We regret that it wasn't + feasible to retain the three dropped options. + + Exim version 4.77 ----------------- @@ -35,6 +121,9 @@ 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. + [nb: gnutls_require_protocols removed in Exim 4.80, instead use + tls_require_ciphers to provide a priority string; see notes above] + * The match_{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