1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 Copyright (c) Todd Lyons <tlyons@exim.org> 2012 - 2014
6 Copyright (c) The Exim Maintainers 2019
9 /* Portions Copyright (c) 2012, 2013, The Trusted Domain Project;
10 All rights reserved, licensed for use per LICENSE.opendmarc. */
12 /* Code for calling dmarc checks via libopendmarc. Called from acl.c. */
16 # if !defined SUPPORT_SPF
17 # error SPF must also be enabled for DMARC
18 # elif defined DISABLE_DKIM
19 # error DKIM must also be enabled for DMARC
22 # include "functions.h"
24 # include "pdkim/pdkim.h"
26 OPENDMARC_LIB_T dmarc_ctx;
27 DMARC_POLICY_T *dmarc_pctx = NULL;
28 OPENDMARC_STATUS_T libdm_status, action, dmarc_policy;
29 OPENDMARC_STATUS_T da, sa, action;
30 BOOL dmarc_abort = FALSE;
31 uschar *dmarc_pass_fail = US"skipped";
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 */
88 /* Set some sane defaults. Also clears previous results when
89 * multiple messages in one connection. */
91 dmarc_status = US"none";
93 dmarc_pass_fail = US"skipped";
94 dmarc_used_domain = US"";
95 f.dmarc_has_been_checked = FALSE;
96 header_from_sender = NULL;
97 spf_sender_domain = NULL;
98 spf_human_readable = NULL;
100 /* ACLs have "control=dmarc_disable_verify" */
101 if (f.dmarc_disable_verify == TRUE)
104 (void) memset(&dmarc_ctx, '\0', sizeof dmarc_ctx);
105 dmarc_ctx.nscount = 0;
106 libdm_status = opendmarc_policy_library_init(&dmarc_ctx);
107 if (libdm_status != DMARC_PARSE_OKAY)
109 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to init library: %s",
110 opendmarc_policy_status_to_str(libdm_status));
113 if (!dmarc_tld_file || !*dmarc_tld_file)
115 DEBUG(D_receive) debug_printf("DMARC: no dmarc_tld_file\n");
118 else if (opendmarc_tld_read_file(CS dmarc_tld_file, NULL, NULL, NULL))
120 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list '%s': %s",
121 dmarc_tld_file, strerror(errno));
124 if (!sender_host_address)
126 DEBUG(D_receive) debug_printf("DMARC: no sender_host_address\n");
129 /* This catches locally originated email and startup errors above. */
132 is_ipv6 = string_is_ip_address(sender_host_address, netmask) == 6;
133 if (!(dmarc_pctx = opendmarc_policy_connect_init(sender_host_address, is_ipv6)))
135 log_write(0, LOG_MAIN|LOG_PANIC,
136 "DMARC failure creating policy context: ip=%s", sender_host_address);
145 /* dmarc_store_data stores the header data so that subsequent
146 dmarc_process can access the data */
149 dmarc_store_data(header_line *hdr)
151 /* No debug output because would change every test debug output */
152 if (!f.dmarc_disable_verify)
159 dmarc_send_forensic_report(u_char **ruf)
161 uschar *recipient, *save_sender;
162 BOOL send_status = FALSE;
163 error_block *eblock = NULL;
164 FILE *message_file = NULL;
166 /* Earlier ACL does not have *required* control=dmarc_enable_forensic */
167 if (!f.dmarc_enable_forensic)
170 if ( dmarc_policy == DMARC_POLICY_REJECT && action == DMARC_RESULT_REJECT
171 || dmarc_policy == DMARC_POLICY_QUARANTINE && action == DMARC_RESULT_QUARANTINE
172 || dmarc_policy == DMARC_POLICY_NONE && action == DMARC_RESULT_REJECT
173 || dmarc_policy == DMARC_POLICY_NONE && action == DMARC_RESULT_QUARANTINE
177 eblock = add_to_eblock(eblock, US"Sender Domain", dmarc_used_domain);
178 eblock = add_to_eblock(eblock, US"Sender IP Address", sender_host_address);
179 eblock = add_to_eblock(eblock, US"Received Date", tod_stamp(tod_full));
180 eblock = add_to_eblock(eblock, US"SPF Alignment",
181 sa == DMARC_POLICY_SPF_ALIGNMENT_PASS ? US"yes" : US"no");
182 eblock = add_to_eblock(eblock, US"DKIM Alignment",
183 da == DMARC_POLICY_DKIM_ALIGNMENT_PASS ? US"yes" : US"no");
184 eblock = add_to_eblock(eblock, US"DMARC Results", dmarc_status_text);
186 for (int c = 0; ruf[c]; c++)
188 recipient = string_copylc(ruf[c]);
189 if (Ustrncmp(recipient, "mailto:",7))
191 /* Move to first character past the colon */
194 debug_printf("DMARC forensic report to %s%s\n", recipient,
195 (host_checking || f.running_in_test_harness) ? " (not really)" : "");
196 if (host_checking || f.running_in_test_harness)
199 if (!moan_send_message(recipient, ERRMESS_DMARC_FORENSIC, eblock,
200 header_list, message_file, NULL))
201 log_write(0, LOG_MAIN|LOG_PANIC,
202 "failure to send DMARC forensic report to %s", recipient);
208 /* Look up a DNS dmarc record for the given domain. Return it or NULL */
211 dmarc_dns_lookup(uschar * dom)
213 dns_answer * dnsa = store_get_dns_answer();
215 int rc = dns_lookup(dnsa, string_sprintf("_dmarc.%s", dom), T_TXT, NULL);
217 if (rc == DNS_SUCCEED)
218 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
219 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
220 if (rr->type == T_TXT && rr->size > 3)
222 store_free_dns_answer(dnsa);
223 return string_copyn_taint(US rr->data, rr->size, TRUE);
225 store_free_dns_answer(dnsa);
231 dmarc_write_history_file()
236 u_char **rua; /* aggregate report addressees */
237 uschar *history_buffer = NULL;
239 if (!dmarc_history_file)
241 DEBUG(D_receive) debug_printf("DMARC history file not set\n");
242 return DMARC_HIST_DISABLED;
244 history_file_fd = log_create(dmarc_history_file);
246 if (history_file_fd < 0)
248 log_write(0, LOG_MAIN|LOG_PANIC, "failure to create DMARC history file: %s",
250 return DMARC_HIST_FILE_ERR;
253 /* Generate the contents of the history file */
254 history_buffer = string_sprintf(
255 "job %s\nreporter %s\nreceived %ld\nipaddr %s\nfrom %s\nmfrom %s\n",
256 message_id, primary_hostname, time(NULL), sender_host_address,
257 header_from_sender, expand_string(US"$sender_address_domain"));
260 history_buffer = string_sprintf("%sspf %d\n", history_buffer, dmarc_spf_ares_result);
261 /* history_buffer = string_sprintf("%sspf -1\n", history_buffer); */
263 history_buffer = string_sprintf(
264 "%s%spdomain %s\npolicy %d\n",
265 history_buffer, dkim_history_buffer, dmarc_used_domain, dmarc_policy);
267 if ((rua = opendmarc_policy_fetch_rua(dmarc_pctx, NULL, 0, 1)))
268 for (tmp_ans = 0; rua[tmp_ans]; tmp_ans++)
269 history_buffer = string_sprintf("%srua %s\n", history_buffer, rua[tmp_ans]);
271 history_buffer = string_sprintf("%srua -\n", history_buffer);
273 opendmarc_policy_fetch_pct(dmarc_pctx, &tmp_ans);
274 history_buffer = string_sprintf("%spct %d\n", history_buffer, tmp_ans);
276 opendmarc_policy_fetch_adkim(dmarc_pctx, &tmp_ans);
277 history_buffer = string_sprintf("%sadkim %d\n", history_buffer, tmp_ans);
279 opendmarc_policy_fetch_aspf(dmarc_pctx, &tmp_ans);
280 history_buffer = string_sprintf("%saspf %d\n", history_buffer, tmp_ans);
282 opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
283 history_buffer = string_sprintf("%sp %d\n", history_buffer, tmp_ans);
285 opendmarc_policy_fetch_sp(dmarc_pctx, &tmp_ans);
286 history_buffer = string_sprintf("%ssp %d\n", history_buffer, tmp_ans);
288 history_buffer = string_sprintf(
289 "%salign_dkim %d\nalign_spf %d\naction %d\n",
290 history_buffer, da, sa, action);
292 /* Write the contents to the history file */
294 debug_printf("DMARC logging history data for opendmarc reporting%s\n",
295 (host_checking || f.running_in_test_harness) ? " (not really)" : "");
296 if (host_checking || f.running_in_test_harness)
299 debug_printf("DMARC history data for debugging:\n%s", history_buffer);
303 written_len = write_to_fd_buf(history_file_fd,
305 Ustrlen(history_buffer));
306 if (written_len == 0)
308 log_write(0, LOG_MAIN|LOG_PANIC, "failure to write to DMARC history file: %s",
310 return DMARC_HIST_WRITE_ERR;
312 (void)close(history_file_fd);
314 return DMARC_HIST_OK;
318 /* dmarc_process adds the envelope sender address to the existing
319 context (if any), retrieves the result, sets up expansion
320 strings and evaluates the condition outcome. */
325 int sr, origin; /* used in SPF section */
326 int dmarc_spf_result = 0; /* stores spf into dmarc conn ctx */
328 pdkim_signature * sig = dkim_signatures;
330 BOOL has_dmarc_record = TRUE;
331 u_char **ruf; /* forensic report addressees, if called for */
333 /* ACLs have "control=dmarc_disable_verify" */
334 if (f.dmarc_disable_verify)
337 /* Store the header From: sender domain for this part of DMARC.
338 * If there is no from_header struct, then it's likely this message
339 * is locally generated and relying on fixups to add it. Just skip
340 * the entire DMARC system if we can't find a From: header....or if
341 * there was a previous error.
345 DEBUG(D_receive) debug_printf("DMARC: no From: header\n");
348 else if (!dmarc_abort)
355 f.parse_allow_group = TRUE;
356 p = parse_find_address_end(from_header->text, FALSE);
357 saveend = *p; *p = '\0';
358 if ((header_from_sender = parse_extract_address(from_header->text, &errormsg,
359 &dummy, &dummy, &domain, FALSE)))
360 header_from_sender += domain;
363 /* The opendmarc library extracts the domain from the email address, but
364 * only try to store it if it's not empty. Otherwise, skip out of DMARC. */
365 if (!header_from_sender || (strcmp( CCS header_from_sender, "") == 0))
367 libdm_status = dmarc_abort
369 : opendmarc_policy_store_from_domain(dmarc_pctx, header_from_sender);
370 if (libdm_status != DMARC_PARSE_OKAY)
372 log_write(0, LOG_MAIN|LOG_PANIC,
373 "failure to store header From: in DMARC: %s, header was '%s'",
374 opendmarc_policy_status_to_str(libdm_status), from_header->text);
379 /* Skip DMARC if connection is SMTP Auth. Temporarily, admin should
380 * instead do this in the ACLs. */
381 if (!dmarc_abort && !sender_host_authenticated)
383 uschar * dmarc_domain;
385 /* Use the envelope sender domain for this part of DMARC */
386 spf_sender_domain = expand_string(US"$sender_address_domain");
389 /* No spf data means null envelope sender so generate a domain name
390 * from the sender_helo_name */
391 if (!spf_sender_domain)
393 spf_sender_domain = sender_helo_name;
394 log_write(0, LOG_MAIN, "DMARC using synthesized SPF sender domain = %s\n",
397 debug_printf("DMARC using synthesized SPF sender domain = %s\n",
400 dmarc_spf_result = DMARC_POLICY_SPF_OUTCOME_NONE;
401 dmarc_spf_ares_result = ARES_RESULT_UNKNOWN;
402 origin = DMARC_POLICY_SPF_ORIGIN_HELO;
403 spf_human_readable = US"";
407 sr = spf_response->result;
408 dmarc_spf_result = sr == SPF_RESULT_NEUTRAL ? DMARC_POLICY_SPF_OUTCOME_NONE :
409 sr == SPF_RESULT_PASS ? DMARC_POLICY_SPF_OUTCOME_PASS :
410 sr == SPF_RESULT_FAIL ? DMARC_POLICY_SPF_OUTCOME_FAIL :
411 sr == SPF_RESULT_SOFTFAIL ? DMARC_POLICY_SPF_OUTCOME_TMPFAIL :
412 DMARC_POLICY_SPF_OUTCOME_NONE;
413 dmarc_spf_ares_result = sr == SPF_RESULT_NEUTRAL ? ARES_RESULT_NEUTRAL :
414 sr == SPF_RESULT_PASS ? ARES_RESULT_PASS :
415 sr == SPF_RESULT_FAIL ? ARES_RESULT_FAIL :
416 sr == SPF_RESULT_SOFTFAIL ? ARES_RESULT_SOFTFAIL :
417 sr == SPF_RESULT_NONE ? ARES_RESULT_NONE :
418 sr == SPF_RESULT_TEMPERROR ? ARES_RESULT_TEMPERROR :
419 sr == SPF_RESULT_PERMERROR ? ARES_RESULT_PERMERROR :
421 origin = DMARC_POLICY_SPF_ORIGIN_MAILFROM;
422 spf_human_readable = US spf_response->header_comment;
424 debug_printf("DMARC using SPF sender domain = %s\n", spf_sender_domain);
426 if (strcmp( CCS spf_sender_domain, "") == 0)
430 libdm_status = opendmarc_policy_store_spf(dmarc_pctx, spf_sender_domain,
431 dmarc_spf_result, origin, spf_human_readable);
432 if (libdm_status != DMARC_PARSE_OKAY)
433 log_write(0, LOG_MAIN|LOG_PANIC, "failure to store spf for DMARC: %s",
434 opendmarc_policy_status_to_str(libdm_status));
437 /* Now we cycle through the dkim signature results and put into
438 * the opendmarc context, further building the DMARC reply. */
439 dkim_history_buffer = US"";
442 int dkim_result, dkim_ares_result, vs, ves;
444 vs = sig->verify_status & ~PDKIM_VERIFY_POLICY;
445 ves = sig->verify_ext_status;
446 dkim_result = vs == PDKIM_VERIFY_PASS ? DMARC_POLICY_DKIM_OUTCOME_PASS :
447 vs == PDKIM_VERIFY_FAIL ? DMARC_POLICY_DKIM_OUTCOME_FAIL :
448 vs == PDKIM_VERIFY_INVALID ? DMARC_POLICY_DKIM_OUTCOME_TMPFAIL :
449 DMARC_POLICY_DKIM_OUTCOME_NONE;
450 libdm_status = opendmarc_policy_store_dkim(dmarc_pctx, US sig->domain,
453 debug_printf("DMARC adding DKIM sender domain = %s\n", sig->domain);
454 if (libdm_status != DMARC_PARSE_OKAY)
455 log_write(0, LOG_MAIN|LOG_PANIC,
456 "failure to store dkim (%s) for DMARC: %s",
457 sig->domain, opendmarc_policy_status_to_str(libdm_status));
460 vs == PDKIM_VERIFY_PASS ? ARES_RESULT_PASS :
461 vs == PDKIM_VERIFY_FAIL ? ARES_RESULT_FAIL :
462 vs == PDKIM_VERIFY_NONE ? ARES_RESULT_NONE :
463 vs == PDKIM_VERIFY_INVALID ?
464 ves == PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE ? ARES_RESULT_PERMERROR :
465 ves == PDKIM_VERIFY_INVALID_BUFFER_SIZE ? ARES_RESULT_PERMERROR :
466 ves == PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD ? ARES_RESULT_PERMERROR :
467 ves == PDKIM_VERIFY_INVALID_PUBKEY_IMPORT ? ARES_RESULT_PERMERROR :
468 ARES_RESULT_UNKNOWN :
470 dkim_history_buffer = string_sprintf("%sdkim %s %d\n", dkim_history_buffer,
471 sig->domain, dkim_ares_result);
475 /* Look up DMARC policy record in DNS. We do this explicitly, rather than
476 letting the dmarc library do it with opendmarc_policy_query_dmarc(), so that
477 our dns access path is used for debug tracing and for the testsuite
480 libdm_status = (rr = dmarc_dns_lookup(header_from_sender))
481 ? opendmarc_policy_store_dmarc(dmarc_pctx, rr, header_from_sender, NULL)
482 : DMARC_DNS_ERROR_NO_RECORD;
483 switch (libdm_status)
485 case DMARC_DNS_ERROR_NXDOMAIN:
486 case DMARC_DNS_ERROR_NO_RECORD:
488 debug_printf("DMARC no record found for %s\n", header_from_sender);
489 has_dmarc_record = FALSE;
491 case DMARC_PARSE_OKAY:
493 debug_printf("DMARC record found for %s\n", header_from_sender);
495 case DMARC_PARSE_ERROR_BAD_VALUE:
497 debug_printf("DMARC record parse error for %s\n", header_from_sender);
498 has_dmarc_record = FALSE;
501 /* everything else, skip dmarc */
503 debug_printf("DMARC skipping (%d), unsure what to do with %s",
504 libdm_status, from_header->text);
505 has_dmarc_record = FALSE;
509 /* Store the policy string in an expandable variable. */
511 libdm_status = opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
512 for (c = 0; dmarc_policy_description[c].name; c++)
513 if (tmp_ans == dmarc_policy_description[c].value)
515 dmarc_domain_policy = string_sprintf("%s",dmarc_policy_description[c].name);
519 /* Can't use exim's string manipulation functions so allocate memory
520 for libopendmarc using its max hostname length definition. */
522 dmarc_domain = store_get(DMARC_MAXHOSTNAMELEN, TRUE);
523 libdm_status = opendmarc_policy_fetch_utilized_domain(dmarc_pctx,
524 dmarc_domain, DMARC_MAXHOSTNAMELEN-1);
525 store_release_above(dmarc_domain + Ustrlen(dmarc_domain)+1);
526 dmarc_used_domain = dmarc_domain;
528 if (libdm_status != DMARC_PARSE_OKAY)
529 log_write(0, LOG_MAIN|LOG_PANIC,
530 "failure to read domainname used for DMARC lookup: %s",
531 opendmarc_policy_status_to_str(libdm_status));
533 dmarc_policy = libdm_status = opendmarc_get_policy_to_enforce(dmarc_pctx);
536 case DMARC_POLICY_ABSENT: /* No DMARC record found */
537 dmarc_status = US"norecord";
538 dmarc_pass_fail = US"none";
539 dmarc_status_text = US"No DMARC record";
540 action = DMARC_RESULT_ACCEPT;
542 case DMARC_FROM_DOMAIN_ABSENT: /* No From: domain */
543 dmarc_status = US"nofrom";
544 dmarc_pass_fail = US"temperror";
545 dmarc_status_text = US"No From: domain found";
546 action = DMARC_RESULT_ACCEPT;
548 case DMARC_POLICY_NONE: /* Accept and report */
549 dmarc_status = US"none";
550 dmarc_pass_fail = US"none";
551 dmarc_status_text = US"None, Accept";
552 action = DMARC_RESULT_ACCEPT;
554 case DMARC_POLICY_PASS: /* Explicit accept */
555 dmarc_status = US"accept";
556 dmarc_pass_fail = US"pass";
557 dmarc_status_text = US"Accept";
558 action = DMARC_RESULT_ACCEPT;
560 case DMARC_POLICY_REJECT: /* Explicit reject */
561 dmarc_status = US"reject";
562 dmarc_pass_fail = US"fail";
563 dmarc_status_text = US"Reject";
564 action = DMARC_RESULT_REJECT;
566 case DMARC_POLICY_QUARANTINE: /* Explicit quarantine */
567 dmarc_status = US"quarantine";
568 dmarc_pass_fail = US"fail";
569 dmarc_status_text = US"Quarantine";
570 action = DMARC_RESULT_QUARANTINE;
573 dmarc_status = US"temperror";
574 dmarc_pass_fail = US"temperror";
575 dmarc_status_text = US"Internal Policy Error";
576 action = DMARC_RESULT_TEMPFAIL;
580 libdm_status = opendmarc_policy_fetch_alignment(dmarc_pctx, &da, &sa);
581 if (libdm_status != DMARC_PARSE_OKAY)
582 log_write(0, LOG_MAIN|LOG_PANIC, "failure to read DMARC alignment: %s",
583 opendmarc_policy_status_to_str(libdm_status));
585 if (has_dmarc_record)
587 log_write(0, LOG_MAIN, "DMARC results: spf_domain=%s dmarc_domain=%s "
588 "spf_align=%s dkim_align=%s enforcement='%s'",
589 spf_sender_domain, dmarc_used_domain,
590 sa==DMARC_POLICY_SPF_ALIGNMENT_PASS ?"yes":"no",
591 da==DMARC_POLICY_DKIM_ALIGNMENT_PASS ?"yes":"no",
593 history_file_status = dmarc_write_history_file();
594 /* Now get the forensic reporting addresses, if any */
595 ruf = opendmarc_policy_fetch_ruf(dmarc_pctx, NULL, 0, 1);
596 dmarc_send_forensic_report(ruf);
600 /* shut down libopendmarc */
602 (void) opendmarc_policy_connect_shutdown(dmarc_pctx);
603 if (!f.dmarc_disable_verify)
604 (void) opendmarc_policy_library_shutdown(&dmarc_ctx);
610 dmarc_exim_expand_query(int what)
612 if (f.dmarc_disable_verify || !dmarc_pctx)
613 return dmarc_exim_expand_defaults(what);
615 if (what == DMARC_VERIFY_STATUS)
621 dmarc_exim_expand_defaults(int what)
623 if (what == DMARC_VERIFY_STATUS)
624 return f.dmarc_disable_verify ? US"off" : US"none";
630 authres_dmarc(gstring * g)
632 if (f.dmarc_has_been_checked)
634 g = string_append(g, 2, US";\n\tdmarc=", dmarc_pass_fail);
635 if (header_from_sender)
636 g = string_append(g, 2, US" header.from=", header_from_sender);
641 # endif /* SUPPORT_SPF */
642 #endif /* SUPPORT_DMARC */