TLS fixes for OpenSSL.
[exim.git] / src / README.UPDATING
1 This document contains detailed information about incompatibilities that might
2 be encountered when upgrading from one release of Exim to another. The
3 information is in reverse order of release numbers. Mostly these are relatively
4 small points, and the configuration file is normally upwards compatible, but
5 there have been two big upheavals...
8 **************************************************************************
9 * There was a big reworking of the way mail routing works for release *
10 * 4.00. Previously used "directors" were abolished, and all routing is *
11 * now done by routers. Policy controls for incoming mail are now done by *
12 * Access Control Lists instead of separate options. All this means that *
13 * pre-4.00 configuration files have to be massively converted. If you *
14 * are coming from a 3.xx release, please read the document in the file *
15 * doc/Exim4.upgrade, and allow some time to complete the upgrade. *
16 * *
17 * There was a big reworking of the way domain/host/net/address lists are *
18 * handled at release 3.00. If you are coming from a pre-3.00 release, it *
19 * might be easier to start again from a default configuration. Otherwise *
20 * you need to read doc/Exim3.upgrade and do a double conversion of your *
21 * configuration file. *
22 **************************************************************************
25 The rest of this document contains information about changes in 4.xx releases
26 that might affect a running system.
29 Exim version 4.78
30 -----------------
32 * The value of $tls_peerdn is now print-escaped when written to the spool file
33 in a -tls_peerdn line, and unescaped when read back in. We received reports
34 of values with embedded newlines, which caused spool file corruption.
36 If you have a corrupt spool file and you wish to recover the contents after
37 upgrading, then lock the message, replace the new-lines that should be part
38 of the -tls_peerdn line with the two-character sequence \n and then unlock
39 the message. No tool has been provided as we believe this is a rare
40 occurence.
42 * With OpenSSL 1.0.1+, Exim now supports TLS 1.1 and TLS 1.2. If built
43 against 1.0.1a then you will get a warning message and the
44 "openssl_options" value will not parse "no_tlsv1_1": the value changes
45 incompatibly between 1.0.1a and 1.0.1b, because the value chosen for 1.0.1a
46 is infelicitous. We advise avoiding 1.0.1a.
48 "openssl_options" gains "no_tlsv1_1", "no_tlsv1_2" and "no_compression".
52 Exim version 4.77
53 -----------------
55 * GnuTLS will now attempt to use TLS 1.2 and TLS 1.1 before TLS 1.0 and SSL3,
56 if supported by your GnuTLS library. Use the existing
57 "gnutls_require_protocols" option to downgrade this if that will be a
58 problem. Prior to this release, supported values were "TLS1" and "SSL3",
59 so you should be able to update configuration prior to update.
61 * The match_<type>{string1}{string2} expansion conditions no longer subject
62 string2 to string expansion, unless Exim was built with the new
63 "EXPAND_LISTMATCH_RHS" option. Too many people have inadvertently created
64 insecure configurations that way. If you need the functionality and turn on
65 that build option, please let the developers know, and know why, so we can
66 try to provide a safer mechanism for you.
68 The match{}{} expansion condition (for regular expressions) is NOT affected.
69 For match_<type>{s1}{s2}, all list functionality is unchanged. The only
70 change is that a '$' appearing in s2 will not trigger expansion, but instead
71 will be treated as a literal $ sign; the effect is very similar to having
72 wrapped s2 with \N...\N. If s2 contains a named list and the list definition
73 uses $expansions then those _will_ be processed as normal. It is only the
74 point at which s2 is read where expansion is inhibited.
76 If you are trying to test if two email addresses are equal, use eqi{s1}{s2}.
77 If you are testing if the address in s1 occurs in the list of items given
78 in s2, either use the new inlisti{s1}{s2} condition (added in 4.77) or use
79 the pre-existing forany{s2}{eqi{$item}{s1}} condition.
82 Exim version 4.74
83 -----------------
85 * The integrated support for dynamically loadable lookup modules has an ABI
86 change from the modules supported by some OS vendors through an unofficial
87 patch. Don't try to mix & match.
89 * Some parts of the build system are now beginning to assume that the host
90 environment is POSIX. If you're building on a system where POSIX tools are
91 not the default, you might have an easier time if you switch to the POSIX
92 tools. Feel free to report non-POSIX issues as a request for a feature
93 enhancement, but if the POSIX variants are available then the fix will
94 probably just involve some coercion. See the README instructions for
95 building on such hosts.
98 Exim version 4.73
99 -----------------
101 * The Exim run-time user can no longer be root; this was always
102 strongly discouraged, but is now prohibited both at build and
103 run-time. If you need Exim to run routinely as root, you'll need to
104 patch the source and accept the risk. Here be dragons.
106 * Exim will no longer accept a configuration file owned by the Exim
107 run-time user, unless that account is explicitly the value in
108 CONFIGURE_OWNER, which we discourage. Exim now checks to ensure that
109 files are not writeable by other accounts.
111 * The ALT_CONFIG_ROOT_ONLY build option is no longer optional and is forced
112 on; the Exim user can, by default, no longer use -C/-D and retain privilege.
113 Two new build options mitigate this.
115 * TRUSTED_CONFIG_LIST defines a file containing a whitelist of config
116 files that are trusted to be selected by the Exim user; one per line.
117 This is the recommended approach going forward.
119 * WHITELIST_D_MACROS defines a colon-separated list of macro names which
120 the Exim run-time user may safely pass without dropping privileges.
121 Because changes to this involve a recompile, this is not the recommended
122 approach but may ease transition. The values of the macros, when
123 overridden, are constrained to match this regex: ^[A-Za-z0-9_/.-]*$
125 * The system_filter_user option now defaults to the Exim run-time user,
126 rather than root. You can still set it explicitly to root and this
127 can be done with prior versions too, letting you roll versions
128 without needing to change this configuration option.
130 * ClamAV must be at least version 0.95 unless WITH_OLD_CLAMAV_STREAM is
131 defined at build time.
134 Exim version 4.70
135 -----------------
137 1. Experimental Yahoo! Domainkeys support has been dropped in this release.
138 It has been superceded by a native implementation of its successor DKIM.
140 2. Up to version 4.69, Exim came with an embedded version of the PCRE library.
141 As of 4.70, this is no longer the case. To compile Exim, you will need PCRE
142 installed. Most OS distributions have ready-made library and development
143 packages.
146 Exim version 4.68
147 -----------------
149 1. The internal implementation of the database keys that are used for ACL
150 ratelimiting has been tidied up. This means that an update to 4.68 might cause
151 Exim to "forget" previous rates that it had calculated, and reset them to zero.
154 Exim version 4.64
155 -----------------
157 1. Callouts were setting the name used for EHLO/HELO from $smtp_active_
158 hostname. This is wrong, because it relates to the incoming message (and
159 probably the interface on which it is arriving) and not to the outgoing
160 callout (which could be using a different interface). This has been
161 changed to use the value of the helo_data option from the smtp transport
162 instead - this is what is used when a message is actually being sent. If
163 there is no remote transport (possible with a router that sets up host
164 addresses), $smtp_active_hostname is used. This change is mentioned here in
165 case somebody is relying on the use of $smtp_active_hostname.
167 2. A bug has been fixed that might just possibly be something that is relied on
168 in some configurations. In expansion items such as ${if >{xxx}{yyy}...} an
169 empty string (that is {}) was being interpreted as if it was {0} and therefore
170 treated as the number zero. From release 4.64, such strings cause an error
171 because a decimal number, possibly followed by K or M, is required (as has
172 always been documented).
174 3. There has been a change to the GnuTLS support (ChangeLog/PH/20) to improve
175 Exim's performance. Unfortunately, this has the side effect of being slightly
176 non-upwards compatible for versions 4.50 and earlier. If you are upgrading from
177 one of these earlier versions and you use GnuTLS, you must remove the file
178 called gnutls-params in Exim's spool directory. If you don't do this, you will
179 see this error:
181 TLS error on connection from ... (DH params import): Base64 decoding error.
183 Removing the file causes Exim to recompute the relevant encryption parameters
184 and cache them in the new format that was introduced for release 4.51 (May
185 2005). If you are upgrading from release 4.51 or later, there should be no
186 problem.
189 Exim version 4.63
190 -----------------
192 When an SMTP error message is specified in a "message" modifier in an ACL, or
193 in a :fail: or :defer: message in a redirect router, Exim now checks the start
194 of the message for an SMTP error code. This consists of three digits followed
195 by a space, optionally followed by an extended code of the form n.n.n, also
196 followed by a space. If this is the case and the very first digit is the same
197 as the default error code, the code from the message is used instead. If the
198 very first digit is incorrect, a panic error is logged, and the default code is
199 used. This is an incompatible change, but it is not expected to affect many (if
200 any) configurations. It is possible to suppress the use of the supplied code in
201 a redirect router by setting the smtp_error_code option false. In this case,
202 any SMTP code is quietly ignored.
205 Exim version 4.61
206 -----------------
208 1. The default number of ACL variables of each type has been increased to 20,
209 and it's possible to compile Exim with more. You can safely upgrade to this
210 release if you already have messages on the queue with saved ACL variable
211 values. However, if you downgrade from this release with messages on the queue,
212 any saved ACL values they may have will be lost.
214 2. The default value for rfc1413_query_timeout has been changed from 30s to 5s.
217 Exim version 4.54
218 -----------------
220 There was a problem with 4.52/TF/02 in that a "name=" option on control=
221 submission terminated at the next slash, thereby not allowing for slashes in
222 the name. This has been changed so that "name=" takes the rest of the string as
223 its data. It must therefore be the last option.
226 Version 4.53
227 ------------
229 If you are using the experimental Domain Keys support, you must upgrade to
230 at least libdomainkeys 0.67 in order to run this release of Exim.
233 Version 4.51
234 ------------
236 1. The format in which GnuTLS parameters are cached (in the file gnutls-params
237 in the spool directory) has been changed. The new format can also be generated
238 externally, so it is now possible to update the values from outside Exim. This
239 has been implemented in an upwards, BUT NOT downwards, compatible manner.
240 Upgrading should be seamless: when Exim finds that it cannot understand an
241 existing cache file, it generates new parameters and writes them to the cache
242 in the new format. If, however, you downgrade from 4.51 to a previous release,
243 you MUST delete the gnutls-params file in the spool directory, because the
244 older Exim will not recognize the new format.
246 2. When doing a callout as part of verifying an address, Exim was not paying
247 attention to any local part prefix or suffix that was matched by the router
248 that accepted the address. It now behaves in the same way as it does for
249 delivery: the affixes are removed from the local part unless
250 rcpt_include_affixes is set on the transport. If you have a configuration that
251 uses prefixes or suffixes on addresses that could be used for callouts, and you
252 want the affixes to be retained, you must make sure that rcpt_include_affixes
253 is set on the transport.
255 3. Bounce and delay warning messages no longer contain details of delivery
256 errors, except for explicit messages (e.g. generated by :fail:) and SMTP
257 responses from remote hosts.
260 Version 4.50
261 ------------
263 The exicyclog script has been updated to use three-digit numbers in rotated log
264 files if the maximum number to keep is greater than 99. If you are already
265 keeping more than 99, there will be an incompatible change when you upgrade.
266 You will probably want to rename your old log files to the new form before
267 running the new exicyclog.
270 Version 4.42
271 ------------
273 RFC 3848 specifies standard names for the "with" phrase in Received: header
274 lines when AUTH and/or TLS are in use. This is the "received protocol"
275 field. Exim used to use "asmtp" for authenticated SMTP, without any
276 indication (in the protocol name) for TLS use. Now it follows the RFC and
277 uses "esmtpa" if the connection is authenticated, "esmtps" if it is
278 encrypted, and "esmtpsa" if it is both encrypted and authenticated. These names
279 appear in log lines as well as in Received: header lines.
282 Version 4.34
283 ------------
285 Change 4.31/2 gave problems to data ACLs and local_scan() functions that
286 expected to see a Received: header. I have changed to yet another scheme. The
287 Received: header is now generated after the body is received, but before the
288 ACL or local_scan() is called. After they have run, the timestamp in the
289 Received: header is updated.
291 Thus, change (a) of 4.31/2 has been reversed, but change (b) is still true,
292 which is lucky, since I decided it was a bug fix.
295 Version 4.33
296 ------------
298 If an expansion in a condition on a "warn" statement fails because a lookup
299 defers, the "warn" statement is abandoned, and the next ACL statement is
300 processed. Previously this caused the whole ACL to be aborted.
303 Version 4.32
304 ------------
306 Change 4.31/2 has been reversed, as it proved contentious. Recipient callout
307 verification now uses <> in the MAIL command by default, as it did before. A
308 new callout option, "use_sender", has been added to request the other
309 behaviour.
312 Version 4.31
313 ------------
315 1. If you compile Exim to use GnuTLS, it now requires the use of release 1.0.0
316 or greater. The interface to the obsolete 0.8.x releases is no longer
317 supported. There is one externally visible change: the format for the
318 display of Distinguished Names now uses commas as a separator rather than a
319 slash. This is to comply with RFC 2253.
321 2. When a message is received, the Received: header line is now generated when
322 reception is complete, instead of at the start of reception. For messages
323 that take a long time to come in, this changes the meaning of the timestamp.
324 There are several side-effects of this change:
326 (a) If a message is rejected by a DATA or non-SMTP ACL, or by local_scan(),
327 the logged header lines no longer include the local Received: line,
328 because it has not yet been created. If the message is a non-SMTP one,
329 and the error is processed by sending a message to the sender, the copy
330 of the original message that is returned does not have an added
331 Received: line.
333 (b) When a filter file is tested using -bf, no additional Received: header
334 is added to the test message. After some thought, I decided that this
335 is a bug fix.
337 The contents of $received_for are not affected by this change. This
338 variable still contains the single recipient of a message, copied after
339 addresses have been rewritten, but before local_scan() is run.
341 2. Recipient callout verification, like sender verification, was using <> in
342 the MAIL FROM command. This isn't really the right thing, since the actual
343 sender may affect whether the remote host accepts the recipient or not. I
344 have changed it to use the actual sender in the callout; this means that
345 the cache record is now keyed on a recipient/sender pair, not just the
346 recipient address. There doesn't seem to be a real danger of callout loops,
347 since a callout by the remote host to check the sender would use <>.
350 Version 4.30
351 ------------
353 1. I have abolished timeout_DNS as an error that can be detected in retry
354 rules, because it has never worked. Despite the fact that it has been
355 documented since at least release 1.62, there was no code to support it.
356 If you have used it in your retry rules, you will now get a warning message
357 to the log and panic log. It is now treated as plain "timeout".
359 2. After discussion on the mailing list, Exim no longer adds From:, Date:, or
360 Message-Id: header lines to messages that do not originate locally, that is,
361 messages that have an associated sending host address.
363 3. When looking up a host name from an IP address, Exim now tries the DNS
364 first, and only if that fails does it use gethostbyaddr() (or equivalent).
365 This change was made because on some OS, not all the names are given for
366 addresses with multiple PTR records via the gethostbyaddr() interface. The
367 order of lookup can be changed by setting host_lookup_order.
370 Version 4.23
371 ------------
373 1. The new FIXED_NEVER_USERS build-time option creates a list of "never users"
374 that cannot be overridden. The default in the distributed EDITME is "root".
375 If for some reason you were (against advice) running deliveries as root, you
376 will have to ensure that FIXED_NEVER_USERS is not set in your
377 Local/Makefile.
379 2. The ${quote: operator now quotes an empty string, which it did not before.
381 3. Version 4.23 saves the contents of the ACL variables with the message, so
382 that they can be used later. If one of these variables contains a newline,
383 there will be a newline character in the spool that will not be interpreted
384 correctely by a previous version of Exim. (Exim ignores keyed spool file
385 items that it doesn't understand - precisely for this kind of problem - but
386 it expects them all to be on one line.)
388 So the bottom line is: if you have newlines in your ACL variables, you
389 cannot retreat from 4.23.
392 Version 4.21
393 ------------
395 1. The idea of the "warn" ACL verb is that it adds a header or writes to the
396 log only when "message" or "log_message" are set. However, if one of the
397 conditions was an address verification, or a call to a nested ACL, the
398 messages generated by the underlying test were being passed through. This
399 no longer happens. The underlying message is available in $acl_verify_
400 message for both "message" and "log_message" expansions, so it can be
401 passed through if needed.
403 2. The way that the $h_ (and $header_) expansions work has been changed by the
404 addition of RFC 2047 decoding. See the main documentation (the NewStuff file
405 until release 4.30, then the manual) for full details. Briefly, there are
406 now three forms:
408 $rh_xxx: and $rheader_xxx: give the original content of the header
409 line(s), with no processing at all.
411 $bh_xxx: and $bheader_xxx: remove leading and trailing white space, and
412 then decode base64 or quoted-printable "words" within the header text,
413 but do not do charset translation.
415 $h_xxx: and $header_xxx: attempt to translate the $bh_ string to a
416 standard character set.
418 If you have previously been using $h_ expansions to access the raw
419 characters, you should change to $rh_ instead.
421 3. When Exim creates an RFC 2047 encoded word in a header line, it labels it
422 with the default character set from the headers_charset option instead of
423 always using iso-8859-1.
425 4. If TMPDIR is defined in Local/Makefile (default in src/EDITME is
426 TMPDIR="/tmp"), Exim checks for the presence of an environment variable
427 called TMPDIR, and if it finds it is different, it changes its value.
429 5. Following a discussion on the list, the rules by which Exim recognises line
430 endings on incoming messages have been changed. The -dropcr and drop_cr
431 options are now no-ops, retained only for backwards compatibility. The
432 following line terminators are recognized: LF CRLF CR. However, special
433 processing applies to CR:
435 (i) The sequence CR . CR does *not* terminate an incoming SMTP message,
436 nor a local message in the state where . is a terminator.
438 (ii) If a bare CR is encountered in a header line, an extra space is added
439 after the line terminator so as not to end the header. The reasoning
440 behind this is that bare CRs in header lines are most likely either
441 to be mistakes, or people trying to play silly games.
443 6. The code for using daemon_smtp_port, local_interfaces, and the -oX options
444 has been reorganized. It is supposed to be backwards compatible, but it is
445 mentioned here just in case I've screwed up.
449 Version 4.20
450 ------------
452 1. I have tidied and re-organized the code that uses alarm() for imposing time
453 limits on various things. It shouldn't affect anything, but if you notice
454 processes getting stuck, it may be that I've broken something.
456 2. The "arguments" log selector now also logs the current working directory
457 when Exim is called.
459 3. An incompatible change has been made to the appendfile transport. This
460 affects the case when it is used for file deliveries that are set up by
461 .forward and filter files. Previously, any settings of the "file" or
462 "directory" options were ignored. It is hoped that, like the address_file
463 transport in the default configuration, these options were never in fact set
464 on such transports, because they were of no use.
466 Now, if either of these options is set, it is used. The path that is passed
467 by the router is in $address_file (this is not new), so it can be used as
468 part of a longer path, or modified in any other way that expansion permits.
470 If neither "file" nor "directory" is set, the behaviour is unchanged.
472 4. Related to the above: in a filter, if a "save" command specifies a non-
473 absolute path, the value of $home/ is pre-pended. This no longer happens if
474 $home is unset or is set to an empty string.
476 5. Multiple file deliveries from a filter or .forward file can never be
477 batched; the value of batch_max on the transport is ignored for file
478 deliveries. I'm assuming that nobody ever actually set batch_max on the
479 address_file transport - it would have had odd effects previously.
481 6. DESTDIR is the more common variable that ROOT for use when installing
482 software under a different root filing system. The Exim install script now
483 recognizes DESTDIR first; if it is not set, ROOT is used.
485 7. If DESTDIR is set when installing Exim, it no longer prepends its value to
486 the path of the system aliases file that appears in the default
487 configuration (when a default configuration is installed). If an aliases
488 file is actually created, its name *does* use the prefix.
491 Version 4.14
492 ------------
494 1. The default for the maximum number of unknown SMTP commands that Exim will
495 accept before dropping a connection has been reduced from 5 to 3. However, you
496 can now change the value by setting smtp_max_unknown_commands.
498 2. The ${quote: operator has been changed so that it turns newline and carriage
499 return characters into \n and \r, respectively.
501 3. The file names used for maildir messages now include the microsecond time
502 fraction as well as the time in seconds, to cope with systems where the process
503 id can be re-used within the same second. The format is now
505 <time>.H<microsec>P<pid>.<host>
507 This should be a compatible change, but is noted here just in case.
509 4. The rules for creating message ids have changed, to cope with systems where
510 the process id can be re-used within the same second. The format, however, is
511 unchanged, so this should not cause any problems, except as noted in the next
512 item.
514 5. The maximum value for localhost_number has been reduced from 255 to 16, in
515 order to implement the new message id rules. For operating systems that have
516 case-insensitive file systems (Cygwin and Darwin), the limit is 10.
518 6. verify = header_syntax was allowing unqualified addresses in all cases. Now
519 it allows them only for locally generated messages and from hosts that match
520 sender_unqualified_hosts or recipient_unqualified_hosts, respectively.
522 7. For reasons lost in the mists of time, when a pipe transport was run, the
523 environment variable MESSAGE_ID was set to the message ID preceded by 'E' (the
524 form used in Message-ID: header lines). The 'E' has been removed.
527 Version 4.11
528 ------------
530 1. The handling of lines in the configuration file has changed. Previously,
531 macro expansion was applied to logical lines, after continuations had been
532 joined on. This meant that it could not be used in .include lines, which are
533 handled as physical rather than logical lines. Macro expansion is now done on
534 physical lines rather than logical lines. This means there are two
535 incompatibilities:
537 (a) A macro that expands to # to turn a line into a comment now applies only
538 to the physical line where it appears. Previously, it would have caused
539 any following continuations also to be ignored.
541 (b) A macro name can no longer be split over the boundary between a line and
542 its continuation. Actually, this is more of a bug fix. :-)
544 2. The -D command line option must now all be within one command line item.
545 This makes it possible to use -D to set a macro to the empty string by commands
546 such as
548 exim -DABC ...
549 exim -DABC= ...
551 Previously, these items would have moved on to the next item on the command
552 line. To include spaces in a macro definition item, quotes must be used, in
553 which case you can also have spaces after -D and surrounding the equals. For
554 example:
556 exim '-D ABC = something' ...
558 3. The way that addresses that redirect to themselves are handled has been
559 changed, in order to fix an obscure bug. This should not cause any problems
560 except in the case of wanting to go back from a 4.11 (or later) release to an
561 earlier release. If there are undelivered messages on the spool that contain
562 addresses which redirect to themselves, and the redirected addresses have
563 already been delivered, you might get a duplicate delivery if you revert to an
564 earlier Exim.
566 4. The default way of looking up IP addresses for hosts in the manualroute and
567 queryprogram routers has been changed. If "byname" or "bydns" is explicitly
568 specified, there is no change, but if no method is specified, Exim now behaves
569 as follows:
571 First, a DNS lookup is done. If this yields anything other than
572 HOST_NOT_FOUND, that result is used. Otherwise, Exim goes on to try a call to
573 getipnodebyname() (or gethostbyname() on older systems) and the result of the
574 lookup is the result of that call.
576 This change has been made because it has been discovered that on some systems,
577 if a DNS lookup called via getipnodebyname() times out, HOST_NOT_FOUND is
578 returned instead of TRY_AGAIN. Thus, it is safest to try a DNS lookup directly
579 first, and only if that gives a definite "no such host" to try the local
580 function.
582 5. In fixing the minor security problem with pid_file_path, I have removed some
583 backwards-compatible (undocumented) code which was present to ease conversion
584 from Exim 3. In Exim 4, pid_file_path is a literal; in Exim 3 it was allowed to
585 contain "%s", which was replaced by the port number for daemons listening on
586 non-standard ports. In Exim 4, such daemons do not write a pid file. The
587 backwards compatibility feature was to replace "%s" by nothing if it occurred
588 in an Exim 4 setting of pid_file_path. The bug was in this code. I have solved
589 the problem by removing the backwards compatibility feature. Thus, if you still
590 have "%s" somewhere in a setting of pid_file_path, you should remove it.
592 6. There has been an extension to lsearch files. The keys in these files may
593 now be quoted in order to allow for whitespace and colons in them. This means
594 that if you were previously using keys that began with a doublequote, you will
595 now have to wrap them with extra quotes and escape the internal quotes. The
596 possibility that anybody is actually doing this seems extremely remote, but it
597 is documented just in case.
600 Version 4.10
601 ------------
603 The build-time parameter EXIWHAT_KILL_ARG has been renamed EXIWHAT_KILL_SIGNAL
604 to better reflect its function. The OS-specific files have been updated. Only
605 if you have explicitly set this in your Makefile (highly unlikely) do you need
606 to change anything.
608 ****