labelled-process fork function
[exim.git] / src / src / transports / pipe.c
1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4
5 /* Copyright (c) University of Cambridge 1995 - 2018 */
6 /* Copyright (c) The Exim maintainers 2020 */
7 /* See the file NOTICE for conditions of use and distribution. */
8
9
10 #include "../exim.h"
11 #include "pipe.h"
12
13 #ifdef HAVE_SETCLASSRESOURCES
14 #include <login_cap.h>
15 #endif
16
17
18
19 /* Options specific to the pipe transport. They must be in alphabetic
20 order (note that "_" comes before the lower case letters). Those starting
21 with "*" are not settable by the user but are used by the option-reading
22 software for alternative value types. Some options are stored in the transport
23 instance block so as to be publicly visible; these are flagged with opt_public.
24 */
25 #define LOFF(field) OPT_OFF(pipe_transport_options_block, field)
26
27 optionlist pipe_transport_options[] = {
28 { "allow_commands", opt_stringptr, LOFF(allow_commands) },
29 { "batch_id", opt_stringptr | opt_public,
30 OPT_OFF(transport_instance, batch_id) },
31 { "batch_max", opt_int | opt_public,
32 OPT_OFF(transport_instance, batch_max) },
33 { "check_string", opt_stringptr, LOFF(check_string) },
34 { "command", opt_stringptr, LOFF(cmd) },
35 { "environment", opt_stringptr, LOFF(environment) },
36 { "escape_string", opt_stringptr, LOFF(escape_string) },
37 { "force_command", opt_bool, LOFF(force_command) },
38 { "freeze_exec_fail", opt_bool, LOFF(freeze_exec_fail) },
39 { "freeze_signal", opt_bool, LOFF(freeze_signal) },
40 { "ignore_status", opt_bool, LOFF(ignore_status) },
41 { "log_defer_output", opt_bool | opt_public,
42 OPT_OFF(transport_instance, log_defer_output) },
43 { "log_fail_output", opt_bool | opt_public,
44 OPT_OFF(transport_instance, log_fail_output) },
45 { "log_output", opt_bool | opt_public,
46 OPT_OFF(transport_instance, log_output) },
47 { "max_output", opt_mkint, LOFF(max_output) },
48 { "message_prefix", opt_stringptr, LOFF(message_prefix) },
49 { "message_suffix", opt_stringptr, LOFF(message_suffix) },
50 { "path", opt_stringptr, LOFF(path) },
51 { "permit_coredump", opt_bool, LOFF(permit_coredump) },
52 { "pipe_as_creator", opt_bool | opt_public,
53 OPT_OFF(transport_instance, deliver_as_creator) },
54 { "restrict_to_path", opt_bool, LOFF(restrict_to_path) },
55 { "return_fail_output",opt_bool | opt_public,
56 OPT_OFF(transport_instance, return_fail_output) },
57 { "return_output", opt_bool | opt_public,
58 OPT_OFF(transport_instance, return_output) },
59 { "temp_errors", opt_stringptr, LOFF(temp_errors) },
60 { "timeout", opt_time, LOFF(timeout) },
61 { "timeout_defer", opt_bool, LOFF(timeout_defer) },
62 { "umask", opt_octint, LOFF(umask) },
63 { "use_bsmtp", opt_bool, LOFF(use_bsmtp) },
64 #ifdef HAVE_SETCLASSRESOURCES
65 { "use_classresources", opt_bool, LOFF(use_classresources) },
66 #endif
67 { "use_crlf", opt_bool, LOFF(use_crlf) },
68 { "use_shell", opt_bool, LOFF(use_shell) },
69 };
70
71 /* Size of the options list. An extern variable has to be used so that its
72 address can appear in the tables drtables.c. */
73
74 int pipe_transport_options_count =
75 sizeof(pipe_transport_options)/sizeof(optionlist);
76
77
78 #ifdef MACRO_PREDEF
79
80 /* Dummy values */
81 pipe_transport_options_block pipe_transport_option_defaults = {0};
82 void pipe_transport_init(transport_instance *tblock) {}
83 BOOL pipe_transport_entry(transport_instance *tblock, address_item *addr) {return FALSE;}
84
85 #else /*!MACRO_PREDEF*/
86
87
88 /* Default private options block for the pipe transport. */
89
90 pipe_transport_options_block pipe_transport_option_defaults = {
91 NULL, /* cmd */
92 NULL, /* allow_commands */
93 NULL, /* environment */
94 US"/bin:/usr/bin", /* path */
95 NULL, /* message_prefix (reset in init if not bsmtp) */
96 NULL, /* message_suffix (ditto) */
97 US mac_expanded_string(EX_TEMPFAIL) ":" /* temp_errors */
98 mac_expanded_string(EX_CANTCREAT),
99 NULL, /* check_string */
100 NULL, /* escape_string */
101 022, /* umask */
102 20480, /* max_output */
103 60*60, /* timeout */
104 0, /* options */
105 FALSE, /* force_command */
106 FALSE, /* freeze_exec_fail */
107 FALSE, /* freeze_signal */
108 FALSE, /* ignore_status */
109 FALSE, /* permit_coredump */
110 FALSE, /* restrict_to_path */
111 FALSE, /* timeout_defer */
112 FALSE, /* use_shell */
113 FALSE, /* use_bsmtp */
114 FALSE, /* use_classresources */
115 FALSE /* use_crlf */
116 };
117
118
119
120 /*************************************************
121 * Setup entry point *
122 *************************************************/
123
124 /* Called for each delivery in the privileged state, just before the uid/gid
125 are changed and the main entry point is called. In a system that supports the
126 login_cap facilities, this function is used to set the class resource limits
127 for the user. It may also re-enable coredumps.
128
129 Arguments:
130 tblock points to the transport instance
131 addrlist addresses about to be delivered (not used)
132 dummy not used (doesn't pass back data)
133 uid the uid that will be set (not used)
134 gid the gid that will be set (not used)
135 errmsg where to put an error message
136
137 Returns: OK, FAIL, or DEFER
138 */
139
140 static int
141 pipe_transport_setup(transport_instance *tblock, address_item *addrlist,
142 transport_feedback *dummy, uid_t uid, gid_t gid, uschar **errmsg)
143 {
144 pipe_transport_options_block *ob =
145 (pipe_transport_options_block *)(tblock->options_block);
146
147 addrlist = addrlist; /* Keep compiler happy */
148 dummy = dummy;
149 uid = uid;
150 gid = gid;
151 errmsg = errmsg;
152 ob = ob;
153
154 #ifdef HAVE_SETCLASSRESOURCES
155 if (ob->use_classresources)
156 {
157 struct passwd *pw = getpwuid(uid);
158 if (pw != NULL)
159 {
160 login_cap_t *lc = login_getpwclass(pw);
161 if (lc != NULL)
162 {
163 setclassresources(lc);
164 login_close(lc);
165 }
166 }
167 }
168 #endif
169
170 #ifdef RLIMIT_CORE
171 if (ob->permit_coredump)
172 {
173 struct rlimit rl;
174 rl.rlim_cur = RLIM_INFINITY;
175 rl.rlim_max = RLIM_INFINITY;
176 if (setrlimit(RLIMIT_CORE, &rl) < 0)
177 {
178 #ifdef SETRLIMIT_NOT_SUPPORTED
179 if (errno != ENOSYS && errno != ENOTSUP)
180 #endif
181 log_write(0, LOG_MAIN,
182 "delivery setrlimit(RLIMIT_CORE, RLIM_INFINITY) failed: %s",
183 strerror(errno));
184 }
185 }
186 #endif
187
188 return OK;
189 }
190
191
192
193 /*************************************************
194 * Initialization entry point *
195 *************************************************/
196
197 /* Called for each instance, after its options have been read, to
198 enable consistency checks to be done, or anything else that needs
199 to be set up. */
200
201 void
202 pipe_transport_init(transport_instance *tblock)
203 {
204 pipe_transport_options_block *ob =
205 (pipe_transport_options_block *)(tblock->options_block);
206
207 /* Set up the setup entry point, to be called in the privileged state */
208
209 tblock->setup = pipe_transport_setup;
210
211 /* If pipe_as_creator is set, then uid/gid should not be set. */
212
213 if (tblock->deliver_as_creator && (tblock->uid_set || tblock->gid_set ||
214 tblock->expand_uid != NULL || tblock->expand_gid != NULL))
215 log_write(0, LOG_PANIC_DIE|LOG_CONFIG,
216 "both pipe_as_creator and an explicit uid/gid are set for the %s "
217 "transport", tblock->name);
218
219 /* If a fixed uid field is set, then a gid field must also be set. */
220
221 if (tblock->uid_set && !tblock->gid_set && tblock->expand_gid == NULL)
222 log_write(0, LOG_PANIC_DIE|LOG_CONFIG,
223 "user set without group for the %s transport", tblock->name);
224
225 /* Temp_errors must consist only of digits and colons, but there can be
226 spaces round the colons, so allow them too. */
227
228 if (ob->temp_errors != NULL && Ustrcmp(ob->temp_errors, "*") != 0)
229 {
230 size_t p = Ustrspn(ob->temp_errors, "0123456789: ");
231 if (ob->temp_errors[p] != 0)
232 log_write(0, LOG_PANIC_DIE|LOG_CONFIG,
233 "temp_errors must be a list of numbers or an asterisk for the %s "
234 "transport", tblock->name);
235 }
236
237 /* Only one of return_output/return_fail_output or log_output/log_fail_output
238 should be set. */
239
240 if (tblock->return_output && tblock->return_fail_output)
241 log_write(0, LOG_PANIC_DIE|LOG_CONFIG,
242 "both return_output and return_fail_output set for %s transport",
243 tblock->name);
244
245 if (tblock->log_output && tblock->log_fail_output)
246 log_write(0, LOG_PANIC_DIE|LOG_CONFIG,
247 "both log_output and log_fail_output set for the %s transport",
248 tblock->name);
249
250 /* If batch SMTP is set, force the check and escape strings, and arrange that
251 headers are also escaped. */
252
253 if (ob->use_bsmtp)
254 {
255 ob->check_string = US".";
256 ob->escape_string = US"..";
257 ob->options |= topt_escape_headers;
258 }
259
260 /* If not batch SMTP, and message_prefix or message_suffix are unset, insert
261 default values for them. */
262
263 else
264 {
265 if (ob->message_prefix == NULL) ob->message_prefix =
266 US"From ${if def:return_path{$return_path}{MAILER-DAEMON}} ${tod_bsdinbox}\n";
267 if (ob->message_suffix == NULL) ob->message_suffix = US"\n";
268 }
269
270 /* The restrict_to_path and use_shell options are incompatible */
271
272 if (ob->restrict_to_path && ob->use_shell)
273 log_write(0, LOG_PANIC_DIE|LOG_CONFIG,
274 "both restrict_to_path and use_shell set for %s transport",
275 tblock->name);
276
277 /* The allow_commands and use_shell options are incompatible */
278
279 if (ob->allow_commands && ob->use_shell)
280 log_write(0, LOG_PANIC_DIE|LOG_CONFIG,
281 "both allow_commands and use_shell set for %s transport",
282 tblock->name);
283
284 /* Set up the bitwise options for transport_write_message from the various
285 driver options. Only one of body_only and headers_only can be set. */
286
287 ob->options |=
288 (tblock->body_only? topt_no_headers : 0) |
289 (tblock->headers_only? topt_no_body : 0) |
290 (tblock->return_path_add? topt_add_return_path : 0) |
291 (tblock->delivery_date_add? topt_add_delivery_date : 0) |
292 (tblock->envelope_to_add? topt_add_envelope_to : 0) |
293 (ob->use_crlf? topt_use_crlf : 0);
294 }
295
296
297
298 /*************************************************
299 * Set up direct (non-shell) command *
300 *************************************************/
301
302 /* This function is called when a command line is to be parsed by the transport
303 and executed directly, without the use of /bin/sh.
304
305 Arguments:
306 argvptr pointer to anchor for argv vector
307 cmd points to the command string
308 expand_arguments true if expansion is to occur
309 expand_fail error if expansion fails
310 addr chain of addresses
311 tname the transport name
312 ob the transport options block
313
314 Returns: TRUE if all went well; otherwise an error will be
315 set in the first address and FALSE returned
316 */
317
318 static BOOL
319 set_up_direct_command(const uschar ***argvptr, uschar *cmd,
320 BOOL expand_arguments, int expand_fail, address_item *addr, uschar *tname,
321 pipe_transport_options_block *ob)
322 {
323 BOOL permitted = FALSE;
324 const uschar **argv;
325
326 /* Set up "transport <name>" to be put in any error messages, and then
327 call the common function for creating an argument list and expanding
328 the items if necessary. If it fails, this function fails (error information
329 is in the addresses). */
330
331 if (!transport_set_up_command(argvptr, cmd, expand_arguments, expand_fail,
332 addr, string_sprintf("%.50s transport", tname), NULL))
333 return FALSE;
334
335 /* Point to the set-up arguments. */
336
337 argv = *argvptr;
338
339 /* If allow_commands is set, see if the command is in the permitted list. */
340
341 if (ob->allow_commands)
342 {
343 int sep = 0;
344 const uschar *s;
345 uschar *p;
346
347 if (!(s = expand_string(ob->allow_commands)))
348 {
349 addr->transport_return = DEFER;
350 addr->message = string_sprintf("failed to expand string \"%s\" "
351 "for %s transport: %s", ob->allow_commands, tname, expand_string_message);
352 return FALSE;
353 }
354
355 while ((p = string_nextinlist(&s, &sep, NULL, 0)))
356 if (Ustrcmp(p, argv[0]) == 0) { permitted = TRUE; break; }
357 }
358
359 /* If permitted is TRUE it means the command was found in the allowed list, and
360 no further checks are done. If permitted = FALSE, it either means
361 allow_commands wasn't set, or that the command didn't match anything in the
362 list. In both cases, if restrict_to_path is set, we fail if the command
363 contains any slashes, but if restrict_to_path is not set, we must fail the
364 command only if allow_commands is set. */
365
366 if (!permitted)
367 {
368 if (ob->restrict_to_path)
369 {
370 if (Ustrchr(argv[0], '/') != NULL)
371 {
372 addr->transport_return = FAIL;
373 addr->message = string_sprintf("\"/\" found in \"%s\" (command for %s "
374 "transport) - failed for security reasons", cmd, tname);
375 return FALSE;
376 }
377 }
378
379 else if (ob->allow_commands)
380 {
381 addr->transport_return = FAIL;
382 addr->message = string_sprintf("\"%s\" command not permitted by %s "
383 "transport", argv[0], tname);
384 return FALSE;
385 }
386 }
387
388 /* If the command is not an absolute path, search the PATH directories
389 for it. */
390
391 if (argv[0][0] != '/')
392 {
393 int sep = 0;
394 uschar *p;
395 const uschar *listptr = expand_string(ob->path);
396
397 while ((p = string_nextinlist(&listptr, &sep, NULL, 0)))
398 {
399 struct stat statbuf;
400 sprintf(CS big_buffer, "%.256s/%.256s", p, argv[0]);
401 if (Ustat(big_buffer, &statbuf) == 0)
402 {
403 argv[0] = string_copy(big_buffer);
404 break;
405 }
406 }
407 if (!p)
408 {
409 addr->transport_return = FAIL;
410 addr->message = string_sprintf("\"%s\" command not found for %s transport",
411 argv[0], tname);
412 return FALSE;
413 }
414 }
415
416 return TRUE;
417 }
418
419
420 /*************************************************
421 * Set up shell command *
422 *************************************************/
423
424 /* This function is called when a command line is to be passed to /bin/sh
425 without parsing inside the transport.
426
427 Arguments:
428 argvptr pointer to anchor for argv vector
429 cmd points to the command string
430 expand_arguments true if expansion is to occur
431 expand_fail error if expansion fails
432 addr chain of addresses
433 tname the transport name
434
435 Returns: TRUE if all went well; otherwise an error will be
436 set in the first address and FALSE returned
437 */
438
439 static BOOL
440 set_up_shell_command(const uschar ***argvptr, uschar *cmd,
441 BOOL expand_arguments, int expand_fail, address_item *addr, uschar *tname)
442 {
443 const uschar **argv;
444
445 *argvptr = argv = store_get((4)*sizeof(uschar *), FALSE);
446
447 argv[0] = US"/bin/sh";
448 argv[1] = US"-c";
449
450 /* We have to take special action to handle the special "variable" called
451 $pipe_addresses, which is not recognized by the normal expansion function. */
452
453 if (expand_arguments)
454 {
455 uschar * p = Ustrstr(cmd, "pipe_addresses");
456 gstring * g = NULL;
457
458 DEBUG(D_transport)
459 debug_printf("shell pipe command before expansion:\n %s\n", cmd);
460
461 /* Allow $recipients in the expansion iff it comes from a system filter */
462
463 f.enable_dollar_recipients = addr && addr->parent &&
464 Ustrcmp(addr->parent->address, "system-filter") == 0;
465
466 if (p != NULL && (
467 (p > cmd && p[-1] == '$') ||
468 (p > cmd + 1 && p[-2] == '$' && p[-1] == '{' && p[14] == '}')))
469 {
470 uschar *q = p + 14;
471
472 if (p[-1] == '{') { q++; p--; }
473
474 g = string_get(Ustrlen(cmd) + 64);
475 g = string_catn(g, cmd, p - cmd - 1);
476
477 for (address_item * ad = addr; ad; ad = ad->next)
478 {
479 /*XXX string_append_listele() ? */
480 if (ad != addr) g = string_catn(g, US" ", 1);
481 g = string_cat(g, ad->address);
482 }
483
484 g = string_cat(g, q);
485 argv[2] = (cmd = string_from_gstring(g)) ? expand_string(cmd) : NULL;
486 }
487 else
488 argv[2] = expand_string(cmd);
489
490 f.enable_dollar_recipients = FALSE;
491
492 if (!argv[2])
493 {
494 addr->transport_return = f.search_find_defer ? DEFER : expand_fail;
495 addr->message = string_sprintf("Expansion of command \"%s\" "
496 "in %s transport failed: %s",
497 cmd, tname, expand_string_message);
498 return FALSE;
499 }
500
501 DEBUG(D_transport)
502 debug_printf("shell pipe command after expansion:\n %s\n", argv[2]);
503 }
504 else
505 {
506 DEBUG(D_transport)
507 debug_printf("shell pipe command (no expansion):\n %s\n", cmd);
508 argv[2] = cmd;
509 }
510
511 argv[3] = US 0;
512 return TRUE;
513 }
514
515
516
517
518 /*************************************************
519 * Main entry point *
520 *************************************************/
521
522 /* See local README for interface details. This transport always returns FALSE,
523 indicating that the status in the first address is the status for all addresses
524 in a batch. */
525
526 BOOL
527 pipe_transport_entry(
528 transport_instance *tblock, /* data for this instantiation */
529 address_item *addr) /* address(es) we are working on */
530 {
531 pid_t pid, outpid;
532 int fd_in, fd_out, rc;
533 int envcount = 0;
534 int envsep = 0;
535 int expand_fail;
536 pipe_transport_options_block *ob =
537 (pipe_transport_options_block *)(tblock->options_block);
538 int timeout = ob->timeout;
539 BOOL written_ok = FALSE;
540 BOOL expand_arguments;
541 const uschar **argv;
542 uschar *envp[50];
543 const uschar *envlist = ob->environment;
544 uschar *cmd, *ss;
545 uschar *eol = ob->use_crlf ? US"\r\n" : US"\n";
546 transport_ctx tctx = {
547 .tblock = tblock,
548 .addr = addr,
549 .check_string = ob->check_string,
550 .escape_string = ob->escape_string,
551 ob->options | topt_not_socket /* set at initialization time */
552 };
553
554 DEBUG(D_transport) debug_printf("%s transport entered\n", tblock->name);
555
556 /* Set up for the good case */
557
558 addr->transport_return = OK;
559 addr->basic_errno = 0;
560
561 /* Pipes are not accepted as general addresses, but they can be generated from
562 .forward files or alias files. In those cases, the pfr flag is set, and the
563 command to be obeyed is pointed to by addr->local_part; it starts with the pipe
564 symbol. In other cases, the command is supplied as one of the pipe transport's
565 options. */
566
567 if (testflag(addr, af_pfr) && addr->local_part[0] == '|')
568 if (ob->force_command)
569 {
570 /* Enables expansion of $address_pipe into separate arguments */
571 setflag(addr, af_force_command);
572 cmd = ob->cmd;
573 expand_arguments = TRUE;
574 expand_fail = PANIC;
575 }
576 else
577 {
578 cmd = addr->local_part + 1;
579 while (isspace(*cmd)) cmd++;
580 expand_arguments = testflag(addr, af_expand_pipe);
581 expand_fail = FAIL;
582 }
583 else
584 {
585 cmd = ob->cmd;
586 expand_arguments = TRUE;
587 expand_fail = PANIC;
588 }
589
590 /* If no command has been supplied, we are in trouble.
591 * We also check for an empty string since it may be
592 * coming from addr->local_part[0] == '|'
593 */
594
595 if (!cmd || !*cmd)
596 {
597 addr->transport_return = DEFER;
598 addr->message = string_sprintf("no command specified for %s transport",
599 tblock->name);
600 return FALSE;
601 }
602 if (is_tainted(cmd))
603 {
604 addr->message = string_sprintf("Tainted '%s' (command "
605 "for %s transport) not permitted", cmd, tblock->name);
606 addr->transport_return = PANIC;
607 return FALSE;
608 }
609
610 /* When a pipe is set up by a filter file, there may be values for $thisaddress
611 and numerical the variables in existence. These are passed in
612 addr->pipe_expandn for use here. */
613
614 if (expand_arguments && addr->pipe_expandn)
615 {
616 uschar **ss = addr->pipe_expandn;
617 expand_nmax = -1;
618 if (*ss) filter_thisaddress = *ss++;
619 while (*ss)
620 {
621 expand_nstring[++expand_nmax] = *ss;
622 expand_nlength[expand_nmax] = Ustrlen(*ss++);
623 }
624 }
625
626 /* The default way of processing the command is to split it up into arguments
627 here, and run it directly. This offers some security advantages. However, there
628 are installations that want by default to run commands under /bin/sh always, so
629 there is an option to do that. */
630
631 if (ob->use_shell)
632 {
633 if (!set_up_shell_command(&argv, cmd, expand_arguments, expand_fail, addr,
634 tblock->name)) return FALSE;
635 }
636 else if (!set_up_direct_command(&argv, cmd, expand_arguments, expand_fail, addr,
637 tblock->name, ob)) return FALSE;
638
639 expand_nmax = -1; /* Reset */
640 filter_thisaddress = NULL;
641
642 /* Set up the environment for the command. */
643
644 envp[envcount++] = string_sprintf("LOCAL_PART=%s", deliver_localpart);
645 envp[envcount++] = string_sprintf("LOGNAME=%s", deliver_localpart);
646 envp[envcount++] = string_sprintf("USER=%s", deliver_localpart);
647 envp[envcount++] = string_sprintf("LOCAL_PART_PREFIX=%#s",
648 deliver_localpart_prefix);
649 envp[envcount++] = string_sprintf("LOCAL_PART_SUFFIX=%#s",
650 deliver_localpart_suffix);
651 envp[envcount++] = string_sprintf("DOMAIN=%s", deliver_domain);
652 envp[envcount++] = string_sprintf("HOME=%#s", deliver_home);
653 envp[envcount++] = string_sprintf("MESSAGE_ID=%s", message_id);
654 envp[envcount++] = string_sprintf("PATH=%s", expand_string(ob->path));
655 envp[envcount++] = string_sprintf("RECIPIENT=%#s%#s%#s@%#s",
656 deliver_localpart_prefix, deliver_localpart, deliver_localpart_suffix,
657 deliver_domain);
658 envp[envcount++] = string_sprintf("QUALIFY_DOMAIN=%s", qualify_domain_sender);
659 envp[envcount++] = string_sprintf("SENDER=%s", sender_address);
660 envp[envcount++] = US"SHELL=/bin/sh";
661
662 if (addr->host_list != NULL)
663 envp[envcount++] = string_sprintf("HOST=%s", addr->host_list->name);
664
665 if (f.timestamps_utc) envp[envcount++] = US"TZ=UTC";
666 else if (timezone_string != NULL && timezone_string[0] != 0)
667 envp[envcount++] = string_sprintf("TZ=%s", timezone_string);
668
669 /* Add any requested items */
670
671 if (envlist)
672 if (!(envlist = expand_cstring(envlist)))
673 {
674 addr->transport_return = DEFER;
675 addr->message = string_sprintf("failed to expand string \"%s\" "
676 "for %s transport: %s", ob->environment, tblock->name,
677 expand_string_message);
678 return FALSE;
679 }
680
681 while ((ss = string_nextinlist(&envlist, &envsep, big_buffer, big_buffer_size)))
682 {
683 if (envcount > nelem(envp) - 2)
684 {
685 addr->transport_return = DEFER;
686 addr->basic_errno = E2BIG;
687 addr->message = string_sprintf("too many environment settings for "
688 "%s transport", tblock->name);
689 return FALSE;
690 }
691 envp[envcount++] = string_copy(ss);
692 }
693
694 envp[envcount] = NULL;
695
696 /* If the -N option is set, can't do any more. */
697
698 if (f.dont_deliver)
699 {
700 DEBUG(D_transport)
701 debug_printf("*** delivery by %s transport bypassed by -N option",
702 tblock->name);
703 return FALSE;
704 }
705
706
707 /* Handling the output from the pipe is tricky. If a file for catching this
708 output is provided, we could in theory just hand that fd over to the process,
709 but this isn't very safe because it might loop and carry on writing for
710 ever (which is exactly what happened in early versions of Exim). Therefore we
711 use the standard child_open() function, which creates pipes. We can then read
712 our end of the output pipe and count the number of bytes that come through,
713 chopping the sub-process if it exceeds some limit.
714
715 However, this means we want to run a sub-process with both its input and output
716 attached to pipes. We can't handle that easily from a single parent process
717 using straightforward code such as the transport_write_message() function
718 because the subprocess might not be reading its input because it is trying to
719 write to a full output pipe. The complication of redesigning the world to
720 handle this is too great - simpler just to run another process to do the
721 reading of the output pipe. */
722
723
724 /* As this is a local transport, we are already running with the required
725 uid/gid and current directory. Request that the new process be a process group
726 leader, so we can kill it and all its children on a timeout. */
727
728 if ((pid = child_open(USS argv, envp, ob->umask, &fd_in, &fd_out, TRUE)) < 0)
729 {
730 addr->transport_return = DEFER;
731 addr->message = string_sprintf(
732 "Failed to create child process for %s transport: %s", tblock->name,
733 strerror(errno));
734 return FALSE;
735 }
736 tctx.u.fd = fd_in;
737
738 /* Now fork a process to handle the output that comes down the pipe. */
739
740 if ((outpid = exim_fork(US"pipe-transport output")) < 0)
741 {
742 addr->basic_errno = errno;
743 addr->transport_return = DEFER;
744 addr->message = string_sprintf(
745 "Failed to create process for handling output in %s transport",
746 tblock->name);
747 (void)close(fd_in);
748 (void)close(fd_out);
749 return FALSE;
750 }
751
752 /* This is the code for the output-handling subprocess. Read from the pipe
753 in chunks, and write to the return file if one is provided. Keep track of
754 the number of bytes handled. If the limit is exceeded, try to kill the
755 subprocess group, and in any case close the pipe and exit, which should cause
756 the subprocess to fail. */
757
758 if (outpid == 0)
759 {
760 int count = 0;
761 (void)close(fd_in);
762 set_process_info("reading output from |%s", cmd);
763 while ((rc = read(fd_out, big_buffer, big_buffer_size)) > 0)
764 {
765 if (addr->return_file >= 0)
766 if(write(addr->return_file, big_buffer, rc) != rc)
767 DEBUG(D_transport) debug_printf("Problem writing to return_file\n");
768 count += rc;
769 if (count > ob->max_output)
770 {
771 DEBUG(D_transport) debug_printf("Too much output from pipe - killed\n");
772 if (addr->return_file >= 0)
773 {
774 uschar *message = US"\n\n*** Too much output - remainder discarded ***\n";
775 rc = Ustrlen(message);
776 if(write(addr->return_file, message, rc) != rc)
777 DEBUG(D_transport) debug_printf("Problem writing to return_file\n");
778 }
779 killpg(pid, SIGKILL);
780 break;
781 }
782 }
783 (void)close(fd_out);
784 _exit(0);
785 }
786
787 (void)close(fd_out); /* Not used in this process */
788
789
790 /* Carrying on now with the main parent process. Attempt to write the message
791 to it down the pipe. It is a fallacy to think that you can detect write errors
792 when the sub-process fails to read the pipe. The parent process may complete
793 writing and close the pipe before the sub-process completes. We could sleep a
794 bit here to let the sub-process get going, but it may still not complete. So we
795 ignore all writing errors. (When in the test harness, we do do a short sleep so
796 any debugging output is likely to be in the same order.) */
797
798 testharness_pause_ms(500);
799
800 DEBUG(D_transport) debug_printf("Writing message to pipe\n");
801
802 /* Arrange to time out writes if there is a timeout set. */
803
804 if (timeout > 0)
805 {
806 sigalrm_seen = FALSE;
807 transport_write_timeout = timeout;
808 }
809
810 /* Reset the counter of bytes written */
811
812 transport_count = 0;
813
814 /* First write any configured prefix information */
815
816 if (ob->message_prefix)
817 {
818 uschar *prefix = expand_string(ob->message_prefix);
819 if (!prefix)
820 {
821 addr->transport_return = f.search_find_defer? DEFER : PANIC;
822 addr->message = string_sprintf("Expansion of \"%s\" (prefix for %s "
823 "transport) failed: %s", ob->message_prefix, tblock->name,
824 expand_string_message);
825 return FALSE;
826 }
827 if (!transport_write_block(&tctx, prefix, Ustrlen(prefix), FALSE))
828 goto END_WRITE;
829 }
830
831 /* If the use_bsmtp option is set, we need to write SMTP prefix information.
832 The various different values for batching are handled outside; if there is more
833 than one address available here, all must be included. Force SMTP dot-handling.
834 */
835
836 if (ob->use_bsmtp)
837 {
838 if (!transport_write_string(fd_in, "MAIL FROM:<%s>%s", return_path, eol))
839 goto END_WRITE;
840
841 for (address_item * a = addr; a; a = a->next)
842 if (!transport_write_string(fd_in,
843 "RCPT TO:<%s>%s",
844 transport_rcpt_address(a, tblock->rcpt_include_affixes),
845 eol))
846 goto END_WRITE;
847
848 if (!transport_write_string(fd_in, "DATA%s", eol)) goto END_WRITE;
849 }
850
851 /* Now the actual message */
852
853 if (!transport_write_message(&tctx, 0))
854 goto END_WRITE;
855
856 /* Now any configured suffix */
857
858 if (ob->message_suffix)
859 {
860 uschar *suffix = expand_string(ob->message_suffix);
861 if (!suffix)
862 {
863 addr->transport_return = f.search_find_defer? DEFER : PANIC;
864 addr->message = string_sprintf("Expansion of \"%s\" (suffix for %s "
865 "transport) failed: %s", ob->message_suffix, tblock->name,
866 expand_string_message);
867 return FALSE;
868 }
869 if (!transport_write_block(&tctx, suffix, Ustrlen(suffix), FALSE))
870 goto END_WRITE;
871 }
872
873 /* If local_smtp, write the terminating dot. */
874
875 if (ob->use_bsmtp && !transport_write_string(fd_in, ".%s", eol))
876 goto END_WRITE;
877
878 /* Flag all writing completed successfully. */
879
880 written_ok = TRUE;
881
882 /* Come here if there are errors during writing. */
883
884 END_WRITE:
885
886 /* OK, the writing is now all done. Close the pipe. */
887
888 (void) close(fd_in);
889
890 /* Handle errors during writing. For timeouts, set the timeout for waiting for
891 the child process to 1 second. If the process at the far end of the pipe died
892 without reading all of it, we expect an EPIPE error, which should be ignored.
893 We used also to ignore WRITEINCOMPLETE but the writing function is now cleverer
894 at handling OS where the death of a pipe doesn't give EPIPE immediately. See
895 comments therein. */
896
897 if (!written_ok)
898 {
899 if (errno == ETIMEDOUT)
900 {
901 addr->message = string_sprintf("%stimeout while writing to pipe",
902 f.transport_filter_timed_out ? "transport filter " : "");
903 addr->transport_return = ob->timeout_defer? DEFER : FAIL;
904 timeout = 1;
905 }
906 else if (errno == EPIPE)
907 {
908 debug_printf("transport error EPIPE ignored\n");
909 }
910 else
911 {
912 addr->transport_return = PANIC;
913 addr->basic_errno = errno;
914 if (errno == ERRNO_CHHEADER_FAIL)
915 addr->message =
916 string_sprintf("Failed to expand headers_add or headers_remove: %s",
917 expand_string_message);
918 else if (errno == ERRNO_FILTER_FAIL)
919 addr->message = string_sprintf("Transport filter process failed (%d)%s",
920 addr->more_errno,
921 (addr->more_errno == EX_EXECFAILED)? ": unable to execute command" : "");
922 else if (errno == ERRNO_WRITEINCOMPLETE)
923 addr->message = US"Failed repeatedly to write data";
924 else
925 addr->message = string_sprintf("Error %d", errno);
926 return FALSE;
927 }
928 }
929
930 /* Wait for the child process to complete and take action if the returned
931 status is nonzero. The timeout will be just 1 second if any of the writes
932 above timed out. */
933
934 if ((rc = child_close(pid, timeout)) != 0)
935 {
936 uschar * tmsg = addr->message
937 ? string_sprintf(" (preceded by %s)", addr->message) : US"";
938
939 /* The process did not complete in time; kill its process group and fail
940 the delivery. It appears to be necessary to kill the output process too, as
941 otherwise it hangs on for some time if the actual pipe process is sleeping.
942 (At least, that's what I observed on Solaris 2.5.1.) Since we are failing
943 the delivery, that shouldn't cause any problem. */
944
945 if (rc == -256)
946 {
947 killpg(pid, SIGKILL);
948 kill(outpid, SIGKILL);
949 addr->transport_return = ob->timeout_defer? DEFER : FAIL;
950 addr->message = string_sprintf("pipe delivery process timed out%s", tmsg);
951 }
952
953 /* Wait() failed. */
954
955 else if (rc == -257)
956 {
957 addr->transport_return = PANIC;
958 addr->message = string_sprintf("Wait() failed for child process of %s "
959 "transport: %s%s", tblock->name, strerror(errno), tmsg);
960 }
961
962 /* Since the transport_filter timed out we assume it has sent the child process
963 a malformed or incomplete data stream. Kill off the child process
964 and prevent checking its exit status as it will has probably exited in error.
965 This prevents the transport_filter timeout message from getting overwritten
966 by the exit error which is not the cause of the problem. */
967
968 else if (f.transport_filter_timed_out)
969 {
970 killpg(pid, SIGKILL);
971 kill(outpid, SIGKILL);
972 }
973
974 /* Either the process completed, but yielded a non-zero (necessarily
975 positive) status, or the process was terminated by a signal (rc will contain
976 the negation of the signal number). Treat killing by signal as failure unless
977 status is being ignored. By default, the message is bounced back, unless
978 freeze_signal is set, in which case it is frozen instead. */
979
980 else if (rc < 0)
981 {
982 if (ob->freeze_signal)
983 {
984 addr->transport_return = DEFER;
985 addr->special_action = SPECIAL_FREEZE;
986 addr->message = string_sprintf("Child process of %s transport (running "
987 "command \"%s\") was terminated by signal %d (%s)%s", tblock->name, cmd,
988 -rc, os_strsignal(-rc), tmsg);
989 }
990 else if (!ob->ignore_status)
991 {
992 addr->transport_return = FAIL;
993 addr->message = string_sprintf("Child process of %s transport (running "
994 "command \"%s\") was terminated by signal %d (%s)%s", tblock->name, cmd,
995 -rc, os_strsignal(-rc), tmsg);
996 }
997 }
998
999 /* For positive values (process terminated with non-zero status), we need a
1000 status code to request deferral. A number of systems contain the following
1001 line in sysexits.h:
1002
1003 #define EX_TEMPFAIL 75
1004
1005 with the description
1006
1007 EX_TEMPFAIL -- temporary failure, indicating something that
1008 is not really an error. In sendmail, this means
1009 that a mailer (e.g.) could not create a connection,
1010 and the request should be reattempted later.
1011
1012 Based on this, we use exit code EX_TEMPFAIL as a default to mean "defer" when
1013 not ignoring the returned status. However, there is now an option that
1014 contains a list of temporary codes, with TEMPFAIL and CANTCREAT as defaults.
1015
1016 Another case that needs special treatment is if execve() failed (typically
1017 the command that was given is a non-existent path). By default this is
1018 treated as just another failure, but if freeze_exec_fail is set, the reaction
1019 is to freeze the message rather than bounce the address. Exim used to signal
1020 this failure with EX_UNAVAILABLE, which is defined in many systems as
1021
1022 #define EX_UNAVAILABLE 69
1023
1024 with the description
1025
1026 EX_UNAVAILABLE -- A service is unavailable. This can occur
1027 if a support program or file does not exist. This
1028 can also be used as a catchall message when something
1029 you wanted to do doesn't work, but you don't know why.
1030
1031 However, this can be confused with a command that actually returns 69 because
1032 something *it* wanted is unavailable. At release 4.21, Exim was changed to
1033 use return code 127 instead, because this is what the shell returns when it
1034 is unable to exec a command. We define it as EX_EXECFAILED, and use it in
1035 child.c to signal execve() failure and other unexpected failures such as
1036 setuid() not working - though that won't be the case here because we aren't
1037 changing uid. */
1038
1039 else
1040 {
1041 /* Always handle execve() failure specially if requested to */
1042
1043 if (ob->freeze_exec_fail && rc == EX_EXECFAILED)
1044 {
1045 addr->transport_return = DEFER;
1046 addr->special_action = SPECIAL_FREEZE;
1047 addr->message = string_sprintf("pipe process failed to exec \"%s\"%s",
1048 cmd, tmsg);
1049 }
1050
1051 /* Otherwise take action only if not ignoring status */
1052
1053 else if (!ob->ignore_status)
1054 {
1055 uschar *ss;
1056 gstring * g;
1057
1058 /* If temp_errors is "*" all codes are temporary. Initialization checks
1059 that it's either "*" or a list of numbers. If not "*", scan the list of
1060 temporary failure codes; if any match, the result is DEFER. */
1061
1062 if (ob->temp_errors[0] == '*')
1063 addr->transport_return = DEFER;
1064
1065 else
1066 {
1067 const uschar *s = ob->temp_errors;
1068 uschar *p;
1069 int sep = 0;
1070
1071 addr->transport_return = FAIL;
1072 while ((p = string_nextinlist(&s,&sep,NULL,0)))
1073 if (rc == Uatoi(p)) { addr->transport_return = DEFER; break; }
1074 }
1075
1076 /* Ensure the message contains the expanded command and arguments. This
1077 doesn't have to be brilliantly efficient - it is an error situation. */
1078
1079 addr->message = string_sprintf("Child process of %s transport returned "
1080 "%d", tblock->name, rc);
1081 g = string_cat(NULL, addr->message);
1082
1083 /* If the return code is > 128, it often means that a shell command
1084 was terminated by a signal. */
1085
1086 ss = (rc > 128)?
1087 string_sprintf("(could mean shell command ended by signal %d (%s))",
1088 rc-128, os_strsignal(rc-128)) :
1089 US os_strexit(rc);
1090
1091 if (*ss)
1092 {
1093 g = string_catn(g, US" ", 1);
1094 g = string_cat (g, ss);
1095 }
1096
1097 /* Now add the command and arguments */
1098
1099 g = string_catn(g, US" from command:", 14);
1100
1101 for (int i = 0; i < sizeof(argv)/sizeof(int *) && argv[i] != NULL; i++)
1102 {
1103 BOOL quote = FALSE;
1104 g = string_catn(g, US" ", 1);
1105 if (Ustrpbrk(argv[i], " \t") != NULL)
1106 {
1107 quote = TRUE;
1108 g = string_catn(g, US"\"", 1);
1109 }
1110 g = string_cat(g, argv[i]);
1111 if (quote)
1112 g = string_catn(g, US"\"", 1);
1113 }
1114
1115 /* Add previous filter timeout message, if present. */
1116
1117 if (*tmsg)
1118 g = string_cat(g, tmsg);
1119
1120 addr->message = string_from_gstring(g);
1121 }
1122 }
1123 }
1124
1125 /* Ensure all subprocesses (in particular, the output handling process)
1126 are complete before we pass this point. */
1127
1128 while (wait(&rc) >= 0);
1129
1130 DEBUG(D_transport) debug_printf("%s transport yielded %d\n", tblock->name,
1131 addr->transport_return);
1132
1133 /* If there has been a problem, the message in addr->message contains details
1134 of the pipe command. We don't want to expose these to the world, so we set up
1135 something bland to return to the sender. */
1136
1137 if (addr->transport_return != OK)
1138 addr->user_message = US"local delivery failed";
1139
1140 return FALSE;
1141 }
1142
1143 #endif /*!MACRO_PREDEF*/
1144 /* End of transport/pipe.c */