Use LC_ALL=C for building lookups/Makefile.
[exim.git] / doc / doc-txt / NewStuff
1 $Cambridge: exim/doc/doc-txt/NewStuff,v 1.176 2010/06/14 18:51:10 pdp Exp $
2
3 New Features in Exim
4 --------------------
5
6 This file contains descriptions of new features that have been added to Exim.
7 Before a formal release, there may be quite a lot of detail so that people can
8 test from the snapshots or the CVS before the documentation is updated. Once
9 the documentation is updated, this file is reduced to a short list.
10
11
12 Version 4.74
13 ------------
14
15 1. SECURITY FIX: privilege escalation flaw fixed. On Linux (and only Linux)
16 the flaw permitted the Exim run-time user to cause root to append to
17 arbitrary files of the attacker's choosing, with the content based
18 on content supplied by the attacker.
19
20 2. Exim now supports loading some lookup types at run-time, using your
21 platform's dlopen() functionality. This has limited platform support
22 and the intention is not to support every variant, it's limited to
23 dlopen(). This permits the main Exim binary to not be linked against
24 all the libraries needed for all the lookup types.
25
26
27 Version 4.73
28 ------------
29
30 NOTE: this version is not guaranteed backwards-compatible, please read the
31 items below carefully
32
33 1. A new main configuration option, "openssl_options", is available if Exim
34 is built with SSL support provided by OpenSSL. The option allows
35 administrators to specify OpenSSL options to be used on connections;
36 typically this is to set bug compatibility features which the OpenSSL
37 developers have not enabled by default. There may be security
38 consequences for certain options, so these should not be changed
39 frivolously.
40
41 2. A new pipe transport option, "permit_coredumps", may help with problem
42 diagnosis in some scenarios. Note that Exim is typically installed as
43 a setuid binary, which on most OSes will inhibit coredumps by default,
44 so that safety mechanism would have to be overriden for this option to
45 be able to take effect.
46
47 3. ClamAV 0.95 is now required for ClamAV support in Exim, unless
48 Local/Makefile sets: WITH_OLD_CLAMAV_STREAM=yes
49 Note that this switches Exim to use a new API ("INSTREAM") and a future
50 release of ClamAV will remove support for the old API ("STREAM").
51
52 The av_scanner option, when set to "clamd", now takes an optional third
53 part, "local", which causes Exim to pass a filename to ClamAV instead of
54 the file content. This is the same behaviour as when clamd is pointed at
55 a Unix-domain socket. For example:
56
57 av_scanner = clamd:192.0.2.3 1234:local
58
59 ClamAV's ExtendedDetectionInfo response format is now handled.
60
61 4. There is now a -bmalware option, restricted to admin users. This option
62 takes one parameter, a filename, and scans that file with Exim's
63 malware-scanning framework. This is intended purely as a debugging aid
64 to ensure that Exim's scanning is working, not to replace other tools.
65 Note that the ACL framework is not invoked, so if av_scanner references
66 ACL variables without a fallback then this will fail.
67
68 5. There is a new expansion operator, "reverse_ip", which will reverse IP
69 addresses; IPv4 into dotted quad, IPv6 into dotted nibble. Examples:
70
71 ${reverse_ip:192.0.2.4}
72 -> 4.2.0.192
73 ${reverse_ip:2001:0db8:c42:9:1:abcd:192.0.2.3}
74 -> 3.0.2.0.0.0.0.c.d.c.b.a.1.0.0.0.9.0.0.0.2.4.c.0.8.b.d.0.1.0.0.2
75
76 6. There is a new ACL control called "debug", to enable debug logging.
77 This allows selective logging of certain incoming transactions within
78 production environments, with some care. It takes two options, "tag"
79 and "opts"; "tag" is included in the filename of the log and "opts"
80 is used as per the -d<options> command-line option. Examples, which
81 don't all make sense in all contexts:
82
83 control = debug
84 control = debug/tag=.$sender_host_address
85 control = debug/opts=+expand+acl
86 control = debug/tag=.$message_exim_id/opts=+expand
87
88 7. It has always been implicit in the design and the documentation that
89 "the Exim user" is not root. src/EDITME said that using root was
90 "very strongly discouraged". This is not enough to keep people from
91 shooting themselves in the foot in days when many don't configure Exim
92 themselves but via package build managers. The security consequences of
93 running various bits of network code are severe if there should be bugs in
94 them. As such, the Exim user may no longer be root. If configured
95 statically, Exim will refuse to build. If configured as ref:user then Exim
96 will exit shortly after start-up. If you must shoot yourself in the foot,
97 then henceforth you will have to maintain your own local patches to strip
98 the safeties off.
99
100 8. There is a new expansion operator, bool_lax{}. Where bool{} uses the ACL
101 condition logic to determine truth/failure and will fail to expand many
102 strings, bool_lax{} uses the router condition logic, where most strings
103 do evaluate true.
104 Note: bool{00} is false, bool_lax{00} is true.
105
106 9. Routers now support multiple "condition" tests,
107
108 10. There is now a runtime configuration option "tcp_wrappers_daemon_name".
109 Setting this allows an admin to define which entry in the tcpwrappers
110 config file will be used to control access to the daemon. This option
111 is only available when Exim is built with USE_TCP_WRAPPERS. The
112 default value is set at build time using the TCP_WRAPPERS_DAEMON_NAME
113 build option.
114
115 11. [POSSIBLE CONFIG BREAKAGE] The default value for system_filter_user is now
116 the Exim run-time user, instead of root.
117
118 12. [POSSIBLE CONFIG BREAKAGE] ALT_CONFIG_ROOT_ONLY is no longer optional and
119 is forced on. This is mitigated by the new build option
120 TRUSTED_CONFIG_LIST which defines a list of configuration files which
121 are trusted; one per line. If a config file is owned by root and matches
122 a pathname in the list, then it may be invoked by the Exim build-time
123 user without Exim relinquishing root privileges.
124
125 13. [POSSIBLE CONFIG BREAKAGE] The Exim user is no longer automatically
126 trusted to supply -D<Macro[=Value]> overrides on the command-line. Going
127 forward, we recommend using TRUSTED_CONFIG_LIST with shim configs that
128 include the main config. As a transition mechanism, we are temporarily
129 providing a work-around: the new build option WHITELIST_D_MACROS provides
130 a colon-separated list of macro names which may be overriden by the Exim
131 run-time user. The values of these macros are constrained to the regex
132 ^[A-Za-z0-9_/.-]*$ (which explicitly does allow for empty values).
133
134
135 Version 4.72
136 ------------
137
138 1. TWO SECURITY FIXES: one relating to mail-spools which are globally
139 writable, the other to locking of MBX folders (not mbox).
140
141 2. MySQL stored procedures are now supported.
142
143 3. The dkim_domain transport option is now a list, not a single string, and
144 messages will be signed for each element in the list (discarding
145 duplicates).
146
147 4. The 4.70 release unexpectedly changed the behaviour of dnsdb TXT lookups
148 in the presence of multiple character strings within the RR. Prior to 4.70,
149 only the first string would be returned. The dnsdb lookup now, by default,
150 preserves the pre-4.70 semantics, but also now takes an extended output
151 separator specification. The separator can be followed by a semicolon, to
152 concatenate the individual text strings together with no join character,
153 or by a comma and a second separator character, in which case the text
154 strings within a TXT record are joined on that second character.
155 Administrators are reminded that DNS provides no ordering guarantees
156 between multiple records in an RRset. For example:
157
158 foo.example. IN TXT "a" "b" "c"
159 foo.example. IN TXT "d" "e" "f"
160
161 ${lookup dnsdb{>/ txt=foo.example}} -> "a/d"
162 ${lookup dnsdb{>/; txt=foo.example}} -> "def/abc"
163 ${lookup dnsdb{>/,+ txt=foo.example}} -> "a+b+c/d+e+f"
164
165
166 Version 4.70 / 4.71
167 -------------------
168
169 1. Native DKIM support without an external library.
170 (Note that if no action to prevent it is taken, a straight upgrade will
171 result in DKIM verification of all signed incoming emails. See spec
172 for details on conditionally disabling)
173
174 2. Experimental DCC support via dccifd (contributed by Wolfgang Breyha).
175
176 3. There is now a bool{} expansion condition which maps certain strings to
177 true/false condition values (most likely of use in conjunction with the
178 and{} expansion operator).
179
180 4. The $spam_score, $spam_bar and $spam_report variables are now available
181 at delivery time.
182
183 5. exim -bP now supports "macros", "macro_list" or "macro MACRO_NAME" as
184 options, provided that Exim is invoked by an admin_user.
185
186 6. There is a new option gnutls_compat_mode, when linked against GnuTLS,
187 which increases compatibility with older clients at the cost of decreased
188 security. Don't set this unless you need to support such clients.
189
190 7. There is a new expansion operator, ${randint:...} which will produce a
191 "random" number less than the supplied integer. This randomness is
192 not guaranteed to be cryptographically strong, but depending upon how
193 Exim was built may be better than the most naive schemes.
194
195 8. Exim now explicitly ensures that SHA256 is available when linked against
196 OpenSSL.
197
198 9. The transport_filter_timeout option now applies to SMTP transports too.
199
200
201 Version 4.69
202 ------------
203
204 1. Preliminary DKIM support in Experimental.
205
206
207 Version 4.68
208 ------------
209
210 1. The body_linecount and body_zerocount C variables are now exported in the
211 local_scan API.
212
213 2. When a dnslists lookup succeeds, the key that was looked up is now placed
214 in $dnslist_matched. When the key is an IP address, it is not reversed in
215 this variable (though it is, of course, in the actual lookup). In simple
216 cases, for example:
217
218 deny dnslists = spamhaus.example
219
220 the key is also available in another variable (in this case,
221 $sender_host_address). In more complicated cases, however, this is not
222 true. For example, using a data lookup might generate a dnslists lookup
223 like this:
224
225 deny dnslists = spamhaus.example/<|192.168.1.2|192.168.6.7|...
226
227 If this condition succeeds, the value in $dnslist_matched might be
228 192.168.6.7 (for example).
229
230 3. Authenticators now have a client_condition option. When Exim is running as
231 a client, it skips an authenticator whose client_condition expansion yields
232 "0", "no", or "false". This can be used, for example, to skip plain text
233 authenticators when the connection is not encrypted by a setting such as:
234
235 client_condition = ${if !eq{$tls_cipher}{}}
236
237 Note that the 4.67 documentation states that $tls_cipher contains the
238 cipher used for incoming messages. In fact, during SMTP delivery, it
239 contains the cipher used for the delivery. The same is true for
240 $tls_peerdn.
241
242 4. There is now a -Mvc <message-id> option, which outputs a copy of the
243 message to the standard output, in RFC 2822 format. The option can be used
244 only by an admin user.
245
246 5. There is now a /noupdate option for the ratelimit ACL condition. It
247 computes the rate and checks the limit as normal, but it does not update
248 the saved data. This means that, in relevant ACLs, it is possible to lookup
249 the existence of a specified (or auto-generated) ratelimit key without
250 incrementing the ratelimit counter for that key.
251
252 In order for this to be useful, another ACL entry must set the rate
253 for the same key somewhere (otherwise it will always be zero).
254
255 Example:
256
257 acl_check_connect:
258 # Read the rate; if it doesn't exist or is below the maximum
259 # we update it below
260 deny ratelimit = 100 / 5m / strict / noupdate
261 log_message = RATE: $sender_rate / $sender_rate_period \
262 (max $sender_rate_limit)
263
264 [... some other logic and tests...]
265
266 warn ratelimit = 100 / 5m / strict / per_cmd
267 log_message = RATE UPDATE: $sender_rate / $sender_rate_period \
268 (max $sender_rate_limit)
269 condition = ${if le{$sender_rate}{$sender_rate_limit}}
270
271 accept
272
273 6. The variable $max_received_linelength contains the number of bytes in the
274 longest line that was received as part of the message, not counting the
275 line termination character(s).
276
277 7. Host lists can now include +ignore_defer and +include_defer, analagous to
278 +ignore_unknown and +include_unknown. These options should be used with
279 care, probably only in non-critical host lists such as whitelists.
280
281 8. There's a new option called queue_only_load_latch, which defaults true.
282 If set false when queue_only_load is greater than zero, Exim re-evaluates
283 the load for each incoming message in an SMTP session. Otherwise, once one
284 message is queued, the remainder are also.
285
286 9. There is a new ACL, specified by acl_smtp_notquit, which is run in most
287 cases when an SMTP session ends without sending QUIT. However, when Exim
288 itself is is bad trouble, such as being unable to write to its log files,
289 this ACL is not run, because it might try to do things (such as write to
290 log files) that make the situation even worse.
291
292 Like the QUIT ACL, this new ACL is provided to make it possible to gather
293 statistics. Whatever it returns (accept or deny) is immaterial. The "delay"
294 modifier is forbidden in this ACL.
295
296 When the NOTQUIT ACL is running, the variable $smtp_notquit_reason is set
297 to a string that indicates the reason for the termination of the SMTP
298 connection. The possible values are:
299
300 acl-drop Another ACL issued a "drop" command
301 bad-commands Too many unknown or non-mail commands
302 command-timeout Timeout while reading SMTP commands
303 connection-lost The SMTP connection has been lost
304 data-timeout Timeout while reading message data
305 local-scan-error The local_scan() function crashed
306 local-scan-timeout The local_scan() function timed out
307 signal-exit SIGTERM or SIGINT
308 synchronization-error SMTP synchronization error
309 tls-failed TLS failed to start
310
311 In most cases when an SMTP connection is closed without having received
312 QUIT, Exim sends an SMTP response message before actually closing the
313 connection. With the exception of acl-drop, the default message can be
314 overridden by the "message" modifier in the NOTQUIT ACL. In the case of a
315 "drop" verb in another ACL, it is the message from the other ACL that is
316 used.
317
318 10. For MySQL and PostgreSQL lookups, it is now possible to specify a list of
319 servers with individual queries. This is done by starting the query with
320 "servers=x:y:z;", where each item in the list may take one of two forms:
321
322 (1) If it is just a host name, the appropriate global option (mysql_servers
323 or pgsql_servers) is searched for a host of the same name, and the
324 remaining parameters (database, user, password) are taken from there.
325
326 (2) If it contains any slashes, it is taken as a complete parameter set.
327
328 The list of servers is used in exactly the same was as the global list.
329 Once a connection to a server has happened and a query has been
330 successfully executed, processing of the lookup ceases.
331
332 This feature is intended for use in master/slave situations where updates
333 are occurring, and one wants to update a master rather than a slave. If the
334 masters are in the list for reading, you might have:
335
336 mysql_servers = slave1/db/name/pw:slave2/db/name/pw:master/db/name/pw
337
338 In an updating lookup, you could then write
339
340 ${lookup mysql{servers=master; UPDATE ...}
341
342 If, on the other hand, the master is not to be used for reading lookups:
343
344 pgsql_servers = slave1/db/name/pw:slave2/db/name/pw
345
346 you can still update the master by
347
348 ${lookup pgsql{servers=master/db/name/pw; UPDATE ...}
349
350 11. The message_body_newlines option (default FALSE, for backwards
351 compatibility) can be used to control whether newlines are present in
352 $message_body and $message_body_end. If it is FALSE, they are replaced by
353 spaces.
354
355
356 Version 4.67
357 ------------
358
359 1. There is a new log selector called smtp_no_mail, which is not included in
360 the default setting. When it is set, a line is written to the main log
361 whenever an accepted SMTP connection terminates without having issued a
362 MAIL command.
363
364 2. When an item in a dnslists list is followed by = and & and a list of IP
365 addresses, the behaviour was not clear when the lookup returned more than
366 one IP address. This has been solved by the addition of == and =& for "all"
367 rather than the default "any" matching.
368
369 3. Up till now, the only control over which cipher suites GnuTLS uses has been
370 for the cipher algorithms. New options have been added to allow some of the
371 other parameters to be varied.
372
373 4. There is a new compile-time option called ENABLE_DISABLE_FSYNC. When it is
374 set, Exim compiles a runtime option called disable_fsync.
375
376 5. There is a new variable called $smtp_count_at_connection_start.
377
378 6. There's a new control called no_pipelining.
379
380 7. There are two new variables called $sending_ip_address and $sending_port.
381 These are set whenever an SMTP connection to another host has been set up.
382
383 8. The expansion of the helo_data option in the smtp transport now happens
384 after the connection to the server has been made.
385
386 9. There is a new expansion operator ${rfc2047d: that decodes strings that
387 are encoded as per RFC 2047.
388
389 10. There is a new log selector called "pid", which causes the current process
390 id to be added to every log line, in square brackets, immediately after the
391 time and date.
392
393 11. Exim has been modified so that it flushes SMTP output before implementing
394 a delay in an ACL. It also flushes the output before performing a callout,
395 as this can take a substantial time. These behaviours can be disabled by
396 obeying control = no_delay_flush or control = no_callout_flush,
397 respectively, at some earlier stage of the connection.
398
399 12. There are two new expansion conditions that iterate over a list. They are
400 called forany and forall.
401
402 13. There's a new global option called dsn_from that can be used to vary the
403 contents of From: lines in bounces and other automatically generated
404 messages ("delivery status notifications" - hence the name of the option).
405
406 14. The smtp transport has a new option called hosts_avoid_pipelining.
407
408 15. By default, exigrep does case-insensitive matches. There is now a -I option
409 that makes it case-sensitive.
410
411 16. A number of new features ("addresses", "map", "filter", and "reduce") have
412 been added to string expansions to make it easier to process lists of
413 items, typically addresses.
414
415 17. There's a new ACL modifier called "continue". It does nothing of itself,
416 and processing of the ACL always continues with the next condition or
417 modifier. It is provided so that the side effects of expanding its argument
418 can be used.
419
420 18. It is now possible to use newline and other control characters (those with
421 values less than 32, plus DEL) as separators in lists.
422
423 19. The exigrep utility now has a -v option, which inverts the matching
424 condition.
425
426 20. The host_find_failed option in the manualroute router can now be set to
427 "ignore".
428
429
430 Version 4.66
431 ------------
432
433 No new features were added to 4.66.
434
435
436 Version 4.65
437 ------------
438
439 No new features were added to 4.65.
440
441
442 Version 4.64
443 ------------
444
445 1. ACL variables can now be given arbitrary names, as long as they start with
446 "acl_c" or "acl_m" (for connection variables and message variables), are at
447 least six characters long, with the sixth character being either a digit or
448 an underscore.
449
450 2. There is a new ACL modifier called log_reject_target. It makes it possible
451 to specify which logs are used for messages about ACL rejections.
452
453 3. There is a new authenticator called "dovecot". This is an interface to the
454 authentication facility of the Dovecot POP/IMAP server, which can support a
455 number of authentication methods.
456
457 4. The variable $message_headers_raw provides a concatenation of all the
458 messages's headers without any decoding. This is in contrast to
459 $message_headers, which does RFC2047 decoding on the header contents.
460
461 5. In a DNS black list, if two domain names, comma-separated, are given, the
462 second is used first to do an initial check, making use of any IP value
463 restrictions that are set. If there is a match, the first domain is used,
464 without any IP value restrictions, to get the TXT record.
465
466 6. All authenticators now have a server_condition option.
467
468 7. There is a new command-line option called -Mset. It is useful only in
469 conjunction with -be (that is, when testing string expansions). It must be
470 followed by a message id; Exim loads the given message from its spool
471 before doing the expansions.
472
473 8. Another similar new command-line option is called -bem. It operates like
474 -be except that it must be followed by the name of a file that contains a
475 message.
476
477 9. When an address is delayed because of a 4xx response to a RCPT command, it
478 is now the combination of sender and recipient that is delayed in
479 subsequent queue runs until its retry time is reached.
480
481 10. Unary negation and the bitwise logical operators and, or, xor, not, and
482 shift, have been added to the eval: and eval10: expansion items.
483
484 11. The variables $interface_address and $interface_port have been renamed
485 as $received_ip_address and $received_port, to make it clear that they
486 relate to message reception rather than delivery. (The old names remain
487 available for compatibility.)
488
489 12. The "message" modifier can now be used on "accept" and "discard" acl verbs
490 to vary the message that is sent when an SMTP command is accepted.
491
492
493 Version 4.63
494 ------------
495
496 1. There is a new Boolean option called filter_prepend_home for the redirect
497 router.
498
499 2. There is a new acl, set by acl_not_smtp_start, which is run right at the
500 start of receiving a non-SMTP message, before any of the message has been
501 read.
502
503 3. When an SMTP error message is specified in a "message" modifier in an ACL,
504 or in a :fail: or :defer: message in a redirect router, Exim now checks the
505 start of the message for an SMTP error code.
506
507 4. There is a new parameter for LDAP lookups called "referrals", which takes
508 one of the settings "follow" (the default) or "nofollow".
509
510 5. Version 20070721.2 of exipick now included, offering these new options:
511 --reverse
512 After all other sorting options have bee processed, reverse order
513 before displaying messages (-R is synonym).
514 --random
515 Randomize order of matching messages before displaying.
516 --size
517 Instead of displaying the matching messages, display the sum
518 of their sizes.
519 --sort <variable>[,<variable>...]
520 Before displaying matching messages, sort the messages according to
521 each messages value for each variable.
522 --not
523 Negate the value for every test (returns inverse output from the
524 same criteria without --not).
525
526
527 Version 4.62
528 ------------
529
530 1. The ${readsocket expansion item now supports Internet domain sockets as well
531 as Unix domain sockets. If the first argument begins "inet:", it must be of
532 the form "inet:host:port". The port is mandatory; it may be a number or the
533 name of a TCP port in /etc/services. The host may be a name, or it may be an
534 IP address. An ip address may optionally be enclosed in square brackets.
535 This is best for IPv6 addresses. For example:
536
537 ${readsocket{inet:[::1]:1234}{<request data>}...
538
539 Only a single host name may be given, but if looking it up yield more than
540 one IP address, they are each tried in turn until a connection is made. Once
541 a connection has been made, the behaviour is as for ${readsocket with a Unix
542 domain socket.
543
544 2. If a redirect router sets up file or pipe deliveries for more than one
545 incoming address, and the relevant transport has batch_max set greater than
546 one, a batch delivery now occurs.
547
548 3. The appendfile transport has a new option called maildirfolder_create_regex.
549 Its value is a regular expression. For a maildir delivery, this is matched
550 against the maildir directory; if it matches, Exim ensures that a
551 maildirfolder file is created alongside the new, cur, and tmp directories.
552
553
554 Version 4.61
555 ------------
556
557 The documentation is up-to-date for the 4.61 release. Major new features since
558 the 4.60 release are:
559
560 . An option called disable_ipv6, to disable the use of IPv6 completely.
561
562 . An increase in the number of ACL variables to 20 of each type.
563
564 . A change to use $auth1, $auth2, and $auth3 in authenticators instead of $1,
565 $2, $3, (though those are still set) because the numeric variables get used
566 for other things in complicated expansions.
567
568 . The default for rfc1413_query_timeout has been changed from 30s to 5s.
569
570 . It is possible to use setclassresources() on some BSD OS to control the
571 resources used in pipe deliveries.
572
573 . A new ACL modifier called add_header, which can be used with any verb.
574
575 . More errors are detectable in retry rules.
576
577 There are a number of other additions too.
578
579
580 Version 4.60
581 ------------
582
583 The documentation is up-to-date for the 4.60 release. Major new features since
584 the 4.50 release are:
585
586 . Support for SQLite.
587
588 . Support for IGNOREQUOTA in LMTP.
589
590 . Extensions to the "submission mode" features.
591
592 . Support for Client SMTP Authorization (CSA).
593
594 . Support for ratelimiting hosts and users.
595
596 . New expansion items to help with the BATV "prvs" scheme.
597
598 . A "match_ip" condition, that matches an IP address against a list.
599
600 There are many more minor changes.
601
602 ****