X-Git-Url: https://git.exim.org/users/jgh/exim.git/blobdiff_plain/f90a9fd133ac62eb3fa1e834b3bff16360d23500..490b427c90a7540d592fa3cf9017a76b84f5d65e:/src/README.UPDATING diff --git a/src/README.UPDATING b/src/README.UPDATING index 7ce35dff8..dacb5d3aa 100644 --- a/src/README.UPDATING +++ b/src/README.UPDATING @@ -26,11 +26,24 @@ The rest of this document contains information about changes in 4.xx releases that might affect a running system. +Exim version 4.82 +----------------- + + * New option gnutls_enable_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 + + * A per-transport wait- database is no longer updated if the transport + sets "connection_max_messages" to 1, as it can not be used and causes + unnecessary serialisation and load.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. + + 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 @@ -42,6 +55,12 @@ Exim version 4.80 the message. No tool has been provided as we believe this is a rare occurence. + * 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 "openssl_options" value will not parse "no_tlsv1_1": the value changes @@ -51,8 +70,9 @@ 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 - "+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 @@ -66,12 +86,23 @@ 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 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 @@ -111,6 +142,40 @@ 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. + * 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 -----------------