1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4 /* Experimental DMARC support.
5 Copyright (c) Todd Lyons <tlyons@exim.org> 2012 - 2014
8 /* Portions Copyright (c) 2012, 2013, The Trusted Domain Project;
9 All rights reserved, licensed for use per LICENSE.opendmarc. */
11 /* Code for calling dmarc checks via libopendmarc. Called from acl.c. */
14 #ifdef EXPERIMENTAL_DMARC
15 # if !defined SUPPORT_SPF
16 # error SPF must also be enabled for DMARC
17 # elif defined DISABLE_DKIM
18 # error DKIM must also be enabled for DMARC
21 # include "functions.h"
23 # include "pdkim/pdkim.h"
25 OPENDMARC_LIB_T dmarc_ctx;
26 DMARC_POLICY_T *dmarc_pctx = NULL;
27 OPENDMARC_STATUS_T libdm_status, action, dmarc_policy;
28 OPENDMARC_STATUS_T da, sa, action;
29 BOOL dmarc_abort = FALSE;
30 uschar *dmarc_pass_fail = US"skipped";
31 extern pdkim_signature *dkim_signatures;
32 header_line *from_header = NULL;
33 extern SPF_response_t *spf_response;
34 int dmarc_spf_ares_result = 0;
35 uschar *spf_sender_domain = NULL;
36 uschar *spf_human_readable = NULL;
37 u_char *header_from_sender = NULL;
38 int history_file_status = DMARC_HIST_OK;
39 uschar *dkim_history_buffer= NULL;
41 typedef struct dmarc_exim_p {
46 static dmarc_exim_p dmarc_policy_description[] = {
48 { US"", DMARC_RECORD_P_UNSPECIFIED },
49 { US"none", DMARC_RECORD_P_NONE },
50 { US"quarantine", DMARC_RECORD_P_QUARANTINE },
51 { US"reject", DMARC_RECORD_P_REJECT },
54 /* Accept an error_block struct, initialize if empty, parse to the
55 * end, and append the two strings passed to it. Used for adding
56 * variable amounts of value:pair data to the forensic emails. */
59 add_to_eblock(error_block *eblock, uschar *t1, uschar *t2)
61 error_block *eb = store_malloc(sizeof(error_block));
66 /* Find the end of the eblock struct and point it at eb */
67 error_block *tmp = eblock;
68 while(tmp->next != NULL)
78 /* dmarc_init sets up a context that can be re-used for several
79 messages on the same SMTP connection (that come from the
80 same host with the same HELO string) */
85 int *netmask = NULL; /* Ignored */
87 char *tld_file = dmarc_tld_file ? CS dmarc_tld_file : DMARC_TLD_FILE;
89 /* Set some sane defaults. Also clears previous results when
90 * multiple messages in one connection. */
92 dmarc_status = US"none";
94 dmarc_pass_fail = US"skipped";
95 dmarc_used_domain = US"";
96 dmarc_ar_header = NULL;
97 dmarc_has_been_checked = FALSE;
98 header_from_sender = NULL;
99 spf_sender_domain = NULL;
100 spf_human_readable = NULL;
102 /* ACLs have "control=dmarc_disable_verify" */
103 if (dmarc_disable_verify == TRUE)
106 (void) memset(&dmarc_ctx, '\0', sizeof dmarc_ctx);
107 dmarc_ctx.nscount = 0;
108 libdm_status = opendmarc_policy_library_init(&dmarc_ctx);
109 if (libdm_status != DMARC_PARSE_OKAY)
111 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to init library: %s",
112 opendmarc_policy_status_to_str(libdm_status));
115 if (dmarc_tld_file == NULL)
117 else if (opendmarc_tld_read_file(tld_file, NULL, NULL, NULL))
119 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list %s: %d",
123 if (sender_host_address == NULL)
125 /* This catches locally originated email and startup errors above. */
128 is_ipv6 = string_is_ip_address(sender_host_address, netmask) == 6;
129 dmarc_pctx = opendmarc_policy_connect_init(sender_host_address, is_ipv6);
130 if (dmarc_pctx == NULL)
132 log_write(0, LOG_MAIN|LOG_PANIC,
133 "DMARC failure creating policy context: ip=%s", sender_host_address);
142 /* dmarc_store_data stores the header data so that subsequent
143 * dmarc_process can access the data */
145 int dmarc_store_data(header_line *hdr) {
146 /* No debug output because would change every test debug output */
147 if (dmarc_disable_verify != TRUE)
154 dmarc_send_forensic_report(u_char **ruf)
157 uschar *recipient, *save_sender;
158 BOOL send_status = FALSE;
159 error_block *eblock = NULL;
160 FILE *message_file = NULL;
162 /* Earlier ACL does not have *required* control=dmarc_enable_forensic */
163 if (!dmarc_enable_forensic)
166 if ( dmarc_policy == DMARC_POLICY_REJECT && action == DMARC_RESULT_REJECT
167 || dmarc_policy == DMARC_POLICY_QUARANTINE && action == DMARC_RESULT_QUARANTINE
168 || dmarc_policy == DMARC_POLICY_NONE && action == DMARC_RESULT_REJECT
169 || dmarc_policy == DMARC_POLICY_NONE && action == DMARC_RESULT_QUARANTINE
173 eblock = add_to_eblock(eblock, US"Sender Domain", dmarc_used_domain);
174 eblock = add_to_eblock(eblock, US"Sender IP Address", sender_host_address);
175 eblock = add_to_eblock(eblock, US"Received Date", tod_stamp(tod_full));
176 eblock = add_to_eblock(eblock, US"SPF Alignment",
177 (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?US"yes":US"no");
178 eblock = add_to_eblock(eblock, US"DKIM Alignment",
179 (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?US"yes":US"no");
180 eblock = add_to_eblock(eblock, US"DMARC Results", dmarc_status_text);
181 /* Set a sane default envelope sender */
182 dsn_from = dmarc_forensic_sender ? dmarc_forensic_sender :
183 dsn_from ? dsn_from :
184 string_sprintf("do-not-reply@%s",primary_hostname);
185 for (c = 0; ruf[c]; c++)
187 recipient = string_copylc(ruf[c]);
188 if (Ustrncmp(recipient, "mailto:",7))
190 /* Move to first character past the colon */
193 debug_printf("DMARC forensic report to %s%s\n", recipient,
194 (host_checking || running_in_test_harness) ? " (not really)" : "");
195 if (host_checking || running_in_test_harness)
198 save_sender = sender_address;
199 sender_address = recipient;
200 send_status = moan_to_sender(ERRMESS_DMARC_FORENSIC, eblock,
201 header_list, message_file, FALSE);
202 sender_address = save_sender;
204 log_write(0, LOG_MAIN|LOG_PANIC,
205 "failure to send DMARC forensic report to %s", recipient);
210 /* dmarc_process adds the envelope sender address to the existing
211 context (if any), retrieves the result, sets up expansion
212 strings and evaluates the condition outcome. */
217 int sr, origin; /* used in SPF section */
218 int dmarc_spf_result = 0; /* stores spf into dmarc conn ctx */
220 pdkim_signature *sig = NULL;
221 BOOL has_dmarc_record = TRUE;
222 u_char **ruf; /* forensic report addressees, if called for */
224 /* ACLs have "control=dmarc_disable_verify" */
225 if (dmarc_disable_verify)
227 dmarc_ar_header = dmarc_auth_results_header(from_header, NULL);
231 /* Store the header From: sender domain for this part of DMARC.
232 * If there is no from_header struct, then it's likely this message
233 * is locally generated and relying on fixups to add it. Just skip
234 * the entire DMARC system if we can't find a From: header....or if
235 * there was a previous error.
237 if (!from_header || dmarc_abort)
246 parse_allow_group = TRUE;
247 p = parse_find_address_end(from_header->text, FALSE);
248 saveend = *p; *p = '\0';
249 if ((header_from_sender = parse_extract_address(from_header->text, &errormsg,
250 &dummy, &dummy, &domain, FALSE)))
251 header_from_sender += domain;
254 /* The opendmarc library extracts the domain from the email address, but
255 * only try to store it if it's not empty. Otherwise, skip out of DMARC. */
256 if (!header_from_sender || (strcmp( CCS header_from_sender, "") == 0))
258 libdm_status = dmarc_abort ?
260 opendmarc_policy_store_from_domain(dmarc_pctx, header_from_sender);
261 if (libdm_status != DMARC_PARSE_OKAY)
263 log_write(0, LOG_MAIN|LOG_PANIC,
264 "failure to store header From: in DMARC: %s, header was '%s'",
265 opendmarc_policy_status_to_str(libdm_status), from_header->text);
270 /* Skip DMARC if connection is SMTP Auth. Temporarily, admin should
271 * instead do this in the ACLs. */
272 if (!dmarc_abort && !sender_host_authenticated)
274 /* Use the envelope sender domain for this part of DMARC */
275 spf_sender_domain = expand_string(US"$sender_address_domain");
278 /* No spf data means null envelope sender so generate a domain name
279 * from the sender_helo_name */
280 if (!spf_sender_domain)
282 spf_sender_domain = sender_helo_name;
283 log_write(0, LOG_MAIN, "DMARC using synthesized SPF sender domain = %s\n",
286 debug_printf("DMARC using synthesized SPF sender domain = %s\n",
289 dmarc_spf_result = DMARC_POLICY_SPF_OUTCOME_NONE;
290 dmarc_spf_ares_result = ARES_RESULT_UNKNOWN;
291 origin = DMARC_POLICY_SPF_ORIGIN_HELO;
292 spf_human_readable = US"";
296 sr = spf_response->result;
297 dmarc_spf_result = sr == SPF_RESULT_NEUTRAL ? DMARC_POLICY_SPF_OUTCOME_NONE :
298 sr == SPF_RESULT_PASS ? DMARC_POLICY_SPF_OUTCOME_PASS :
299 sr == SPF_RESULT_FAIL ? DMARC_POLICY_SPF_OUTCOME_FAIL :
300 sr == SPF_RESULT_SOFTFAIL ? DMARC_POLICY_SPF_OUTCOME_TMPFAIL :
301 DMARC_POLICY_SPF_OUTCOME_NONE;
302 dmarc_spf_ares_result = sr == SPF_RESULT_NEUTRAL ? ARES_RESULT_NEUTRAL :
303 sr == SPF_RESULT_PASS ? ARES_RESULT_PASS :
304 sr == SPF_RESULT_FAIL ? ARES_RESULT_FAIL :
305 sr == SPF_RESULT_SOFTFAIL ? ARES_RESULT_SOFTFAIL :
306 sr == SPF_RESULT_NONE ? ARES_RESULT_NONE :
307 sr == SPF_RESULT_TEMPERROR ? ARES_RESULT_TEMPERROR :
308 sr == SPF_RESULT_PERMERROR ? ARES_RESULT_PERMERROR :
310 origin = DMARC_POLICY_SPF_ORIGIN_MAILFROM;
311 spf_human_readable = US spf_response->header_comment;
313 debug_printf("DMARC using SPF sender domain = %s\n", spf_sender_domain);
315 if (strcmp( CCS spf_sender_domain, "") == 0)
319 libdm_status = opendmarc_policy_store_spf(dmarc_pctx, spf_sender_domain,
320 dmarc_spf_result, origin, spf_human_readable);
321 if (libdm_status != DMARC_PARSE_OKAY)
322 log_write(0, LOG_MAIN|LOG_PANIC, "failure to store spf for DMARC: %s",
323 opendmarc_policy_status_to_str(libdm_status));
326 /* Now we cycle through the dkim signature results and put into
327 * the opendmarc context, further building the DMARC reply. */
328 sig = dkim_signatures;
329 dkim_history_buffer = US"";
332 int dkim_result, dkim_ares_result, vs, ves;
333 vs = sig->verify_status;
334 ves = sig->verify_ext_status;
335 dkim_result = vs == PDKIM_VERIFY_PASS ? DMARC_POLICY_DKIM_OUTCOME_PASS :
336 vs == PDKIM_VERIFY_FAIL ? DMARC_POLICY_DKIM_OUTCOME_FAIL :
337 vs == PDKIM_VERIFY_INVALID ? DMARC_POLICY_DKIM_OUTCOME_TMPFAIL :
338 DMARC_POLICY_DKIM_OUTCOME_NONE;
339 libdm_status = opendmarc_policy_store_dkim(dmarc_pctx, US sig->domain,
342 debug_printf("DMARC adding DKIM sender domain = %s\n", sig->domain);
343 if (libdm_status != DMARC_PARSE_OKAY)
344 log_write(0, LOG_MAIN|LOG_PANIC,
345 "failure to store dkim (%s) for DMARC: %s",
346 sig->domain, opendmarc_policy_status_to_str(libdm_status));
349 vs == PDKIM_VERIFY_PASS ? ARES_RESULT_PASS :
350 vs == PDKIM_VERIFY_FAIL ? ARES_RESULT_FAIL :
351 vs == PDKIM_VERIFY_NONE ? ARES_RESULT_NONE :
352 vs == PDKIM_VERIFY_INVALID ?
353 ves == PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE ? ARES_RESULT_PERMERROR :
354 ves == PDKIM_VERIFY_INVALID_BUFFER_SIZE ? ARES_RESULT_PERMERROR :
355 ves == PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD ? ARES_RESULT_PERMERROR :
356 ves == PDKIM_VERIFY_INVALID_PUBKEY_IMPORT ? ARES_RESULT_PERMERROR :
357 ARES_RESULT_UNKNOWN :
359 dkim_history_buffer = string_sprintf("%sdkim %s %d\n", dkim_history_buffer,
360 sig->domain, dkim_ares_result);
363 libdm_status = opendmarc_policy_query_dmarc(dmarc_pctx, US"");
364 switch (libdm_status)
366 case DMARC_DNS_ERROR_NXDOMAIN:
367 case DMARC_DNS_ERROR_NO_RECORD:
369 debug_printf("DMARC no record found for %s\n", header_from_sender);
370 has_dmarc_record = FALSE;
372 case DMARC_PARSE_OKAY:
374 debug_printf("DMARC record found for %s\n", header_from_sender);
376 case DMARC_PARSE_ERROR_BAD_VALUE:
378 debug_printf("DMARC record parse error for %s\n", header_from_sender);
379 has_dmarc_record = FALSE;
382 /* everything else, skip dmarc */
384 debug_printf("DMARC skipping (%d), unsure what to do with %s",
385 libdm_status, from_header->text);
386 has_dmarc_record = FALSE;
390 /* Store the policy string in an expandable variable. */
392 libdm_status = opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
393 for (c = 0; dmarc_policy_description[c].name; c++)
394 if (tmp_ans == dmarc_policy_description[c].value)
396 dmarc_domain_policy = string_sprintf("%s",dmarc_policy_description[c].name);
400 /* Can't use exim's string manipulation functions so allocate memory
401 * for libopendmarc using its max hostname length definition. */
403 uschar *dmarc_domain = US calloc(DMARC_MAXHOSTNAMELEN, sizeof(uschar));
404 libdm_status = opendmarc_policy_fetch_utilized_domain(dmarc_pctx,
405 dmarc_domain, DMARC_MAXHOSTNAMELEN-1);
406 dmarc_used_domain = string_copy(dmarc_domain);
409 if (libdm_status != DMARC_PARSE_OKAY)
410 log_write(0, LOG_MAIN|LOG_PANIC,
411 "failure to read domainname used for DMARC lookup: %s",
412 opendmarc_policy_status_to_str(libdm_status));
414 libdm_status = opendmarc_get_policy_to_enforce(dmarc_pctx);
415 dmarc_policy = libdm_status;
418 case DMARC_POLICY_ABSENT: /* No DMARC record found */
419 dmarc_status = US"norecord";
420 dmarc_pass_fail = US"none";
421 dmarc_status_text = US"No DMARC record";
422 action = DMARC_RESULT_ACCEPT;
424 case DMARC_FROM_DOMAIN_ABSENT: /* No From: domain */
425 dmarc_status = US"nofrom";
426 dmarc_pass_fail = US"temperror";
427 dmarc_status_text = US"No From: domain found";
428 action = DMARC_RESULT_ACCEPT;
430 case DMARC_POLICY_NONE: /* Accept and report */
431 dmarc_status = US"none";
432 dmarc_pass_fail = US"none";
433 dmarc_status_text = US"None, Accept";
434 action = DMARC_RESULT_ACCEPT;
436 case DMARC_POLICY_PASS: /* Explicit accept */
437 dmarc_status = US"accept";
438 dmarc_pass_fail = US"pass";
439 dmarc_status_text = US"Accept";
440 action = DMARC_RESULT_ACCEPT;
442 case DMARC_POLICY_REJECT: /* Explicit reject */
443 dmarc_status = US"reject";
444 dmarc_pass_fail = US"fail";
445 dmarc_status_text = US"Reject";
446 action = DMARC_RESULT_REJECT;
448 case DMARC_POLICY_QUARANTINE: /* Explicit quarantine */
449 dmarc_status = US"quarantine";
450 dmarc_pass_fail = US"fail";
451 dmarc_status_text = US"Quarantine";
452 action = DMARC_RESULT_QUARANTINE;
455 dmarc_status = US"temperror";
456 dmarc_pass_fail = US"temperror";
457 dmarc_status_text = US"Internal Policy Error";
458 action = DMARC_RESULT_TEMPFAIL;
462 libdm_status = opendmarc_policy_fetch_alignment(dmarc_pctx, &da, &sa);
463 if (libdm_status != DMARC_PARSE_OKAY)
464 log_write(0, LOG_MAIN|LOG_PANIC, "failure to read DMARC alignment: %s",
465 opendmarc_policy_status_to_str(libdm_status));
467 if (has_dmarc_record == TRUE)
469 log_write(0, LOG_MAIN, "DMARC results: spf_domain=%s dmarc_domain=%s "
470 "spf_align=%s dkim_align=%s enforcement='%s'",
471 spf_sender_domain, dmarc_used_domain,
472 (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?"yes":"no",
473 (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?"yes":"no",
475 history_file_status = dmarc_write_history_file();
476 /* Now get the forensic reporting addresses, if any */
477 ruf = opendmarc_policy_fetch_ruf(dmarc_pctx, NULL, 0, 1);
478 dmarc_send_forensic_report(ruf);
482 /* set some global variables here */
483 dmarc_ar_header = dmarc_auth_results_header(from_header, NULL);
485 /* shut down libopendmarc */
486 if ( dmarc_pctx != NULL )
487 (void) opendmarc_policy_connect_shutdown(dmarc_pctx);
488 if ( dmarc_disable_verify == FALSE )
489 (void) opendmarc_policy_library_shutdown(&dmarc_ctx);
495 dmarc_write_history_file()
500 u_char **rua; /* aggregate report addressees */
501 uschar *history_buffer = NULL;
503 if (!dmarc_history_file)
504 return DMARC_HIST_DISABLED;
505 history_file_fd = log_create(dmarc_history_file);
507 if (history_file_fd < 0)
509 log_write(0, LOG_MAIN|LOG_PANIC, "failure to create DMARC history file: %s",
511 return DMARC_HIST_FILE_ERR;
514 /* Generate the contents of the history file */
515 history_buffer = string_sprintf(
516 "job %s\nreporter %s\nreceived %ld\nipaddr %s\nfrom %s\nmfrom %s\n",
517 message_id, primary_hostname, time(NULL), sender_host_address,
518 header_from_sender, expand_string(US"$sender_address_domain"));
521 history_buffer = string_sprintf("%sspf %d\n", history_buffer, dmarc_spf_ares_result);
522 /* history_buffer = string_sprintf("%sspf -1\n", history_buffer); */
524 history_buffer = string_sprintf(
525 "%s%spdomain %s\npolicy %d\n",
526 history_buffer, dkim_history_buffer, dmarc_used_domain, dmarc_policy);
528 if ((rua = opendmarc_policy_fetch_rua(dmarc_pctx, NULL, 0, 1)))
529 for (tmp_ans = 0; rua[tmp_ans]; tmp_ans++)
530 history_buffer = string_sprintf("%srua %s\n", history_buffer, rua[tmp_ans]);
532 history_buffer = string_sprintf("%srua -\n", history_buffer);
534 opendmarc_policy_fetch_pct(dmarc_pctx, &tmp_ans);
535 history_buffer = string_sprintf("%spct %d\n", history_buffer, tmp_ans);
537 opendmarc_policy_fetch_adkim(dmarc_pctx, &tmp_ans);
538 history_buffer = string_sprintf("%sadkim %d\n", history_buffer, tmp_ans);
540 opendmarc_policy_fetch_aspf(dmarc_pctx, &tmp_ans);
541 history_buffer = string_sprintf("%saspf %d\n", history_buffer, tmp_ans);
543 opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
544 history_buffer = string_sprintf("%sp %d\n", history_buffer, tmp_ans);
546 opendmarc_policy_fetch_sp(dmarc_pctx, &tmp_ans);
547 history_buffer = string_sprintf("%ssp %d\n", history_buffer, tmp_ans);
549 history_buffer = string_sprintf(
550 "%salign_dkim %d\nalign_spf %d\naction %d\n",
551 history_buffer, da, sa, action);
553 /* Write the contents to the history file */
555 debug_printf("DMARC logging history data for opendmarc reporting%s\n",
556 (host_checking || running_in_test_harness) ? " (not really)" : "");
557 if (host_checking || running_in_test_harness)
560 debug_printf("DMARC history data for debugging:\n%s", history_buffer);
564 written_len = write_to_fd_buf(history_file_fd,
566 Ustrlen(history_buffer));
567 if (written_len == 0)
569 log_write(0, LOG_MAIN|LOG_PANIC, "failure to write to DMARC history file: %s",
571 return DMARC_HIST_WRITE_ERR;
573 (void)close(history_file_fd);
575 return DMARC_HIST_OK;
580 dmarc_exim_expand_query(int what)
582 if (dmarc_disable_verify || !dmarc_pctx)
583 return dmarc_exim_expand_defaults(what);
585 if (what == DMARC_VERIFY_STATUS)
591 dmarc_exim_expand_defaults(int what)
593 if (what == DMARC_VERIFY_STATUS)
594 return dmarc_disable_verify ? US"off" : US"none";
599 dmarc_auth_results_header(header_line *from_header, uschar *hostname)
601 uschar *hdr_tmp = US"";
603 /* Allow a server hostname to be passed to this function, but is
604 * currently unused */
606 hostname = primary_hostname;
607 hdr_tmp = string_sprintf("%s %s;", DMARC_AR_HEADER, hostname);
610 /* I don't think this belongs here, but left it here commented out
611 * because it was a lot of work to get working right. */
612 if (spf_response != NULL) {
613 uschar *dmarc_ar_spf = US"";
615 sr = spf_response->result;
616 dmarc_ar_spf = (sr == SPF_RESULT_NEUTRAL) ? US"neutral" :
617 (sr == SPF_RESULT_PASS) ? US"pass" :
618 (sr == SPF_RESULT_FAIL) ? US"fail" :
619 (sr == SPF_RESULT_SOFTFAIL) ? US"softfail" :
621 hdr_tmp = string_sprintf("%s spf=%s (%s) smtp.mail=%s;",
622 hdr_tmp, dmarc_ar_spf_result,
623 spf_response->header_comment,
624 expand_string(US"$sender_address") );
628 hdr_tmp = string_sprintf("%s dmarc=%s", hdr_tmp, dmarc_pass_fail);
629 if (header_from_sender)
630 hdr_tmp = string_sprintf("%s header.from=%s",
631 hdr_tmp, header_from_sender);
635 # endif /* SUPPORT_SPF */
636 #endif /* EXPERIMENTAL_DMARC */