1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
5 Copyright (c) The Exim Maintainers 2019 - 2022
6 Copyright (c) Todd Lyons <tlyons@exim.org> 2012 - 2014
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 },
57 dmarc_version_report(gstring * g)
59 return string_fmt_append(g, "Library version: dmarc: Compile: %d.%d.%d.%d\n",
60 (OPENDMARC_LIB_VERSION & 0xff000000) >> 24, (OPENDMARC_LIB_VERSION & 0x00ff0000) >> 16,
61 (OPENDMARC_LIB_VERSION & 0x0000ff00) >> 8, OPENDMARC_LIB_VERSION & 0x000000ff);
65 /* Accept an error_block struct, initialize if empty, parse to the
66 end, and append the two strings passed to it. Used for adding
67 variable amounts of value:pair data to the forensic emails. */
70 add_to_eblock(error_block *eblock, uschar *t1, uschar *t2)
72 error_block *eb = store_malloc(sizeof(error_block));
77 /* Find the end of the eblock struct and point it at eb */
78 error_block *tmp = eblock;
89 /* dmarc_init sets up a context that can be re-used for several
90 messages on the same SMTP connection (that come from the
91 same host with the same HELO string) */
96 int *netmask = NULL; /* Ignored */
99 /* Set some sane defaults. Also clears previous results when
100 * multiple messages in one connection. */
102 dmarc_status = US"none";
104 dmarc_pass_fail = US"skipped";
105 dmarc_used_domain = US"";
106 f.dmarc_has_been_checked = FALSE;
107 header_from_sender = NULL;
108 spf_sender_domain = NULL;
109 spf_human_readable = NULL;
111 /* ACLs have "control=dmarc_disable_verify" */
112 if (f.dmarc_disable_verify == TRUE)
115 (void) memset(&dmarc_ctx, '\0', sizeof dmarc_ctx);
116 dmarc_ctx.nscount = 0;
117 libdm_status = opendmarc_policy_library_init(&dmarc_ctx);
118 if (libdm_status != DMARC_PARSE_OKAY)
120 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to init library: %s",
121 opendmarc_policy_status_to_str(libdm_status));
124 if (!dmarc_tld_file || !*dmarc_tld_file)
126 DEBUG(D_receive) debug_printf("DMARC: no dmarc_tld_file\n");
129 else if (opendmarc_tld_read_file(CS dmarc_tld_file, NULL, NULL, NULL))
131 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list '%s': %s",
132 dmarc_tld_file, strerror(errno));
135 if (!sender_host_address)
137 DEBUG(D_receive) debug_printf("DMARC: no sender_host_address\n");
140 /* This catches locally originated email and startup errors above. */
143 is_ipv6 = string_is_ip_address(sender_host_address, netmask) == 6;
144 if (!(dmarc_pctx = opendmarc_policy_connect_init(sender_host_address, is_ipv6)))
146 log_write(0, LOG_MAIN|LOG_PANIC,
147 "DMARC failure creating policy context: ip=%s", sender_host_address);
156 /* dmarc_store_data stores the header data so that subsequent
157 dmarc_process can access the data */
160 dmarc_store_data(header_line *hdr)
162 /* No debug output because would change every test debug output */
163 if (!f.dmarc_disable_verify)
170 dmarc_send_forensic_report(u_char **ruf)
172 uschar *recipient, *save_sender;
173 BOOL send_status = FALSE;
174 error_block *eblock = NULL;
175 FILE *message_file = NULL;
177 /* Earlier ACL does not have *required* control=dmarc_enable_forensic */
178 if (!f.dmarc_enable_forensic)
181 if ( dmarc_policy == DMARC_POLICY_REJECT && action == DMARC_RESULT_REJECT
182 || dmarc_policy == DMARC_POLICY_QUARANTINE && action == DMARC_RESULT_QUARANTINE
183 || dmarc_policy == DMARC_POLICY_NONE && action == DMARC_RESULT_REJECT
184 || dmarc_policy == DMARC_POLICY_NONE && action == DMARC_RESULT_QUARANTINE
188 eblock = add_to_eblock(eblock, US"Sender Domain", dmarc_used_domain);
189 eblock = add_to_eblock(eblock, US"Sender IP Address", sender_host_address);
190 eblock = add_to_eblock(eblock, US"Received Date", tod_stamp(tod_full));
191 eblock = add_to_eblock(eblock, US"SPF Alignment",
192 sa == DMARC_POLICY_SPF_ALIGNMENT_PASS ? US"yes" : US"no");
193 eblock = add_to_eblock(eblock, US"DKIM Alignment",
194 da == DMARC_POLICY_DKIM_ALIGNMENT_PASS ? US"yes" : US"no");
195 eblock = add_to_eblock(eblock, US"DMARC Results", dmarc_status_text);
197 for (int c = 0; ruf[c]; c++)
199 recipient = string_copylc(ruf[c]);
200 if (Ustrncmp(recipient, "mailto:",7))
202 /* Move to first character past the colon */
205 debug_printf("DMARC forensic report to %s%s\n", recipient,
206 (host_checking || f.running_in_test_harness) ? " (not really)" : "");
207 if (host_checking || f.running_in_test_harness)
210 if (!moan_send_message(recipient, ERRMESS_DMARC_FORENSIC, eblock,
211 header_list, message_file, NULL))
212 log_write(0, LOG_MAIN|LOG_PANIC,
213 "failure to send DMARC forensic report to %s", recipient);
219 /* Look up a DNS dmarc record for the given domain. Return it or NULL */
222 dmarc_dns_lookup(uschar * dom)
224 dns_answer * dnsa = store_get_dns_answer();
226 int rc = dns_lookup(dnsa, string_sprintf("_dmarc.%s", dom), T_TXT, NULL);
228 if (rc == DNS_SUCCEED)
229 for (dns_record * rr = dns_next_rr(dnsa, &dnss, RESET_ANSWERS); rr;
230 rr = dns_next_rr(dnsa, &dnss, RESET_NEXT))
231 if (rr->type == T_TXT && rr->size > 3)
233 uschar *record = string_copyn_taint(US rr->data, rr->size, GET_TAINTED);
234 store_free_dns_answer(dnsa);
237 store_free_dns_answer(dnsa);
243 dmarc_write_history_file()
248 u_char **rua; /* aggregate report addressees */
249 uschar *history_buffer = NULL;
251 if (!dmarc_history_file)
253 DEBUG(D_receive) debug_printf("DMARC history file not set\n");
254 return DMARC_HIST_DISABLED;
256 history_file_fd = log_open_as_exim(dmarc_history_file);
258 if (history_file_fd < 0)
260 log_write(0, LOG_MAIN|LOG_PANIC, "failure to create DMARC history file: %s",
262 return DMARC_HIST_FILE_ERR;
265 /* Generate the contents of the history file */
266 history_buffer = string_sprintf(
267 "job %s\nreporter %s\nreceived %ld\nipaddr %s\nfrom %s\nmfrom %s\n",
268 message_id, primary_hostname, time(NULL), sender_host_address,
269 header_from_sender, expand_string(US"$sender_address_domain"));
272 history_buffer = string_sprintf("%sspf %d\n", history_buffer, dmarc_spf_ares_result);
273 /* history_buffer = string_sprintf("%sspf -1\n", history_buffer); */
275 history_buffer = string_sprintf(
276 "%s%spdomain %s\npolicy %d\n",
277 history_buffer, dkim_history_buffer, dmarc_used_domain, dmarc_policy);
279 if ((rua = opendmarc_policy_fetch_rua(dmarc_pctx, NULL, 0, 1)))
280 for (tmp_ans = 0; rua[tmp_ans]; tmp_ans++)
281 history_buffer = string_sprintf("%srua %s\n", history_buffer, rua[tmp_ans]);
283 history_buffer = string_sprintf("%srua -\n", history_buffer);
285 opendmarc_policy_fetch_pct(dmarc_pctx, &tmp_ans);
286 history_buffer = string_sprintf("%spct %d\n", history_buffer, tmp_ans);
288 opendmarc_policy_fetch_adkim(dmarc_pctx, &tmp_ans);
289 history_buffer = string_sprintf("%sadkim %d\n", history_buffer, tmp_ans);
291 opendmarc_policy_fetch_aspf(dmarc_pctx, &tmp_ans);
292 history_buffer = string_sprintf("%saspf %d\n", history_buffer, tmp_ans);
294 opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
295 history_buffer = string_sprintf("%sp %d\n", history_buffer, tmp_ans);
297 opendmarc_policy_fetch_sp(dmarc_pctx, &tmp_ans);
298 history_buffer = string_sprintf("%ssp %d\n", history_buffer, tmp_ans);
300 history_buffer = string_sprintf(
301 "%salign_dkim %d\nalign_spf %d\naction %d\n",
302 history_buffer, da, sa, action);
304 /* Write the contents to the history file */
306 debug_printf("DMARC logging history data for opendmarc reporting%s\n",
307 (host_checking || f.running_in_test_harness) ? " (not really)" : "");
308 if (host_checking || f.running_in_test_harness)
311 debug_printf("DMARC history data for debugging:\n%s", history_buffer);
315 written_len = write_to_fd_buf(history_file_fd,
317 Ustrlen(history_buffer));
318 if (written_len == 0)
320 log_write(0, LOG_MAIN|LOG_PANIC, "failure to write to DMARC history file: %s",
322 return DMARC_HIST_WRITE_ERR;
324 (void)close(history_file_fd);
326 return DMARC_HIST_OK;
330 /* dmarc_process adds the envelope sender address to the existing
331 context (if any), retrieves the result, sets up expansion
332 strings and evaluates the condition outcome. */
337 int sr, origin; /* used in SPF section */
338 int dmarc_spf_result = 0; /* stores spf into dmarc conn ctx */
340 pdkim_signature * sig = dkim_signatures;
342 BOOL has_dmarc_record = TRUE;
343 u_char **ruf; /* forensic report addressees, if called for */
345 /* ACLs have "control=dmarc_disable_verify" */
346 if (f.dmarc_disable_verify)
349 /* Store the header From: sender domain for this part of DMARC.
350 * If there is no from_header struct, then it's likely this message
351 * is locally generated and relying on fixups to add it. Just skip
352 * the entire DMARC system if we can't find a From: header....or if
353 * there was a previous error.
357 DEBUG(D_receive) debug_printf("DMARC: no From: header\n");
360 else if (!dmarc_abort)
367 f.parse_allow_group = TRUE;
368 p = parse_find_address_end(from_header->text, FALSE);
369 saveend = *p; *p = '\0';
370 if ((header_from_sender = parse_extract_address(from_header->text, &errormsg,
371 &dummy, &dummy, &domain, FALSE)))
372 header_from_sender += domain;
375 /* The opendmarc library extracts the domain from the email address, but
376 * only try to store it if it's not empty. Otherwise, skip out of DMARC. */
377 if (!header_from_sender || (strcmp( CCS header_from_sender, "") == 0))
379 libdm_status = dmarc_abort
381 : opendmarc_policy_store_from_domain(dmarc_pctx, header_from_sender);
382 if (libdm_status != DMARC_PARSE_OKAY)
384 log_write(0, LOG_MAIN|LOG_PANIC,
385 "failure to store header From: in DMARC: %s, header was '%s'",
386 opendmarc_policy_status_to_str(libdm_status), from_header->text);
391 /* Skip DMARC if connection is SMTP Auth. Temporarily, admin should
392 * instead do this in the ACLs. */
393 if (!dmarc_abort && !sender_host_authenticated)
395 uschar * dmarc_domain;
397 /* Use the envelope sender domain for this part of DMARC */
398 spf_sender_domain = expand_string(US"$sender_address_domain");
401 /* No spf data means null envelope sender so generate a domain name
402 * from the sender_helo_name */
403 if (!spf_sender_domain)
405 spf_sender_domain = sender_helo_name;
406 log_write(0, LOG_MAIN, "DMARC using synthesized SPF sender domain = %s\n",
409 debug_printf("DMARC using synthesized SPF sender domain = %s\n",
412 dmarc_spf_result = DMARC_POLICY_SPF_OUTCOME_NONE;
413 dmarc_spf_ares_result = ARES_RESULT_UNKNOWN;
414 origin = DMARC_POLICY_SPF_ORIGIN_HELO;
415 spf_human_readable = US"";
419 sr = spf_response->result;
420 dmarc_spf_result = sr == SPF_RESULT_NEUTRAL ? DMARC_POLICY_SPF_OUTCOME_NONE :
421 sr == SPF_RESULT_PASS ? DMARC_POLICY_SPF_OUTCOME_PASS :
422 sr == SPF_RESULT_FAIL ? DMARC_POLICY_SPF_OUTCOME_FAIL :
423 sr == SPF_RESULT_SOFTFAIL ? DMARC_POLICY_SPF_OUTCOME_TMPFAIL :
424 DMARC_POLICY_SPF_OUTCOME_NONE;
425 dmarc_spf_ares_result = sr == SPF_RESULT_NEUTRAL ? ARES_RESULT_NEUTRAL :
426 sr == SPF_RESULT_PASS ? ARES_RESULT_PASS :
427 sr == SPF_RESULT_FAIL ? ARES_RESULT_FAIL :
428 sr == SPF_RESULT_SOFTFAIL ? ARES_RESULT_SOFTFAIL :
429 sr == SPF_RESULT_NONE ? ARES_RESULT_NONE :
430 sr == SPF_RESULT_TEMPERROR ? ARES_RESULT_TEMPERROR :
431 sr == SPF_RESULT_PERMERROR ? ARES_RESULT_PERMERROR :
433 origin = DMARC_POLICY_SPF_ORIGIN_MAILFROM;
434 spf_human_readable = US spf_response->header_comment;
436 debug_printf("DMARC using SPF sender domain = %s\n", spf_sender_domain);
438 if (strcmp( CCS spf_sender_domain, "") == 0)
442 libdm_status = opendmarc_policy_store_spf(dmarc_pctx, spf_sender_domain,
443 dmarc_spf_result, origin, spf_human_readable);
444 if (libdm_status != DMARC_PARSE_OKAY)
445 log_write(0, LOG_MAIN|LOG_PANIC, "failure to store spf for DMARC: %s",
446 opendmarc_policy_status_to_str(libdm_status));
449 /* Now we cycle through the dkim signature results and put into
450 * the opendmarc context, further building the DMARC reply. */
451 dkim_history_buffer = US"";
454 int dkim_result, dkim_ares_result, vs, ves;
456 vs = sig->verify_status & ~PDKIM_VERIFY_POLICY;
457 ves = sig->verify_ext_status;
458 dkim_result = vs == PDKIM_VERIFY_PASS ? DMARC_POLICY_DKIM_OUTCOME_PASS :
459 vs == PDKIM_VERIFY_FAIL ? DMARC_POLICY_DKIM_OUTCOME_FAIL :
460 vs == PDKIM_VERIFY_INVALID ? DMARC_POLICY_DKIM_OUTCOME_TMPFAIL :
461 DMARC_POLICY_DKIM_OUTCOME_NONE;
462 libdm_status = opendmarc_policy_store_dkim(dmarc_pctx, US sig->domain,
463 /* The opendmarc project broke its API in a way we can't detect * easily.
464 * The EDITME provides a DMARC_API variable */
465 #if DMARC_API >= 100400
470 debug_printf("DMARC adding DKIM sender domain = %s\n", sig->domain);
471 if (libdm_status != DMARC_PARSE_OKAY)
472 log_write(0, LOG_MAIN|LOG_PANIC,
473 "failure to store dkim (%s) for DMARC: %s",
474 sig->domain, opendmarc_policy_status_to_str(libdm_status));
477 vs == PDKIM_VERIFY_PASS ? ARES_RESULT_PASS :
478 vs == PDKIM_VERIFY_FAIL ? ARES_RESULT_FAIL :
479 vs == PDKIM_VERIFY_NONE ? ARES_RESULT_NONE :
480 vs == PDKIM_VERIFY_INVALID ?
481 ves == PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE ? ARES_RESULT_PERMERROR :
482 ves == PDKIM_VERIFY_INVALID_BUFFER_SIZE ? ARES_RESULT_PERMERROR :
483 ves == PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD ? ARES_RESULT_PERMERROR :
484 ves == PDKIM_VERIFY_INVALID_PUBKEY_IMPORT ? ARES_RESULT_PERMERROR :
485 ARES_RESULT_UNKNOWN :
487 dkim_history_buffer = string_sprintf("%sdkim %s %d\n", dkim_history_buffer,
488 sig->domain, dkim_ares_result);
492 /* Look up DMARC policy record in DNS. We do this explicitly, rather than
493 letting the dmarc library do it with opendmarc_policy_query_dmarc(), so that
494 our dns access path is used for debug tracing and for the testsuite
497 libdm_status = (rr = dmarc_dns_lookup(header_from_sender))
498 ? opendmarc_policy_store_dmarc(dmarc_pctx, rr, header_from_sender, NULL)
499 : DMARC_DNS_ERROR_NO_RECORD;
500 switch (libdm_status)
502 case DMARC_DNS_ERROR_NXDOMAIN:
503 case DMARC_DNS_ERROR_NO_RECORD:
505 debug_printf("DMARC no record found for %s\n", header_from_sender);
506 has_dmarc_record = FALSE;
508 case DMARC_PARSE_OKAY:
510 debug_printf("DMARC record found for %s\n", header_from_sender);
512 case DMARC_PARSE_ERROR_BAD_VALUE:
514 debug_printf("DMARC record parse error for %s\n", header_from_sender);
515 has_dmarc_record = FALSE;
518 /* everything else, skip dmarc */
520 debug_printf("DMARC skipping (%d), unsure what to do with %s",
521 libdm_status, from_header->text);
522 has_dmarc_record = FALSE;
526 /* Store the policy string in an expandable variable. */
528 libdm_status = opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
529 for (c = 0; dmarc_policy_description[c].name; c++)
530 if (tmp_ans == dmarc_policy_description[c].value)
532 dmarc_domain_policy = string_sprintf("%s",dmarc_policy_description[c].name);
536 /* Can't use exim's string manipulation functions so allocate memory
537 for libopendmarc using its max hostname length definition. */
539 dmarc_domain = store_get(DMARC_MAXHOSTNAMELEN, GET_TAINTED);
540 libdm_status = opendmarc_policy_fetch_utilized_domain(dmarc_pctx,
541 dmarc_domain, DMARC_MAXHOSTNAMELEN-1);
542 store_release_above(dmarc_domain + Ustrlen(dmarc_domain)+1);
543 dmarc_used_domain = dmarc_domain;
545 if (libdm_status != DMARC_PARSE_OKAY)
546 log_write(0, LOG_MAIN|LOG_PANIC,
547 "failure to read domainname used for DMARC lookup: %s",
548 opendmarc_policy_status_to_str(libdm_status));
550 dmarc_policy = libdm_status = opendmarc_get_policy_to_enforce(dmarc_pctx);
553 case DMARC_POLICY_ABSENT: /* No DMARC record found */
554 dmarc_status = US"norecord";
555 dmarc_pass_fail = US"none";
556 dmarc_status_text = US"No DMARC record";
557 action = DMARC_RESULT_ACCEPT;
559 case DMARC_FROM_DOMAIN_ABSENT: /* No From: domain */
560 dmarc_status = US"nofrom";
561 dmarc_pass_fail = US"temperror";
562 dmarc_status_text = US"No From: domain found";
563 action = DMARC_RESULT_ACCEPT;
565 case DMARC_POLICY_NONE: /* Accept and report */
566 dmarc_status = US"none";
567 dmarc_pass_fail = US"none";
568 dmarc_status_text = US"None, Accept";
569 action = DMARC_RESULT_ACCEPT;
571 case DMARC_POLICY_PASS: /* Explicit accept */
572 dmarc_status = US"accept";
573 dmarc_pass_fail = US"pass";
574 dmarc_status_text = US"Accept";
575 action = DMARC_RESULT_ACCEPT;
577 case DMARC_POLICY_REJECT: /* Explicit reject */
578 dmarc_status = US"reject";
579 dmarc_pass_fail = US"fail";
580 dmarc_status_text = US"Reject";
581 action = DMARC_RESULT_REJECT;
583 case DMARC_POLICY_QUARANTINE: /* Explicit quarantine */
584 dmarc_status = US"quarantine";
585 dmarc_pass_fail = US"fail";
586 dmarc_status_text = US"Quarantine";
587 action = DMARC_RESULT_QUARANTINE;
590 dmarc_status = US"temperror";
591 dmarc_pass_fail = US"temperror";
592 dmarc_status_text = US"Internal Policy Error";
593 action = DMARC_RESULT_TEMPFAIL;
597 libdm_status = opendmarc_policy_fetch_alignment(dmarc_pctx, &da, &sa);
598 if (libdm_status != DMARC_PARSE_OKAY)
599 log_write(0, LOG_MAIN|LOG_PANIC, "failure to read DMARC alignment: %s",
600 opendmarc_policy_status_to_str(libdm_status));
602 if (has_dmarc_record)
604 log_write(0, LOG_MAIN, "DMARC results: spf_domain=%s dmarc_domain=%s "
605 "spf_align=%s dkim_align=%s enforcement='%s'",
606 spf_sender_domain, dmarc_used_domain,
607 sa==DMARC_POLICY_SPF_ALIGNMENT_PASS ?"yes":"no",
608 da==DMARC_POLICY_DKIM_ALIGNMENT_PASS ?"yes":"no",
610 history_file_status = dmarc_write_history_file();
611 /* Now get the forensic reporting addresses, if any */
612 ruf = opendmarc_policy_fetch_ruf(dmarc_pctx, NULL, 0, 1);
613 dmarc_send_forensic_report(ruf);
617 /* shut down libopendmarc */
619 (void) opendmarc_policy_connect_shutdown(dmarc_pctx);
620 if (!f.dmarc_disable_verify)
621 (void) opendmarc_policy_library_shutdown(&dmarc_ctx);
627 dmarc_exim_expand_query(int what)
629 if (f.dmarc_disable_verify || !dmarc_pctx)
630 return dmarc_exim_expand_defaults(what);
632 if (what == DMARC_VERIFY_STATUS)
638 dmarc_exim_expand_defaults(int what)
640 if (what == DMARC_VERIFY_STATUS)
641 return f.dmarc_disable_verify ? US"off" : US"none";
647 authres_dmarc(gstring * g)
649 if (f.dmarc_has_been_checked)
651 g = string_append(g, 2, US";\n\tdmarc=", dmarc_pass_fail);
652 if (header_from_sender)
653 g = string_append(g, 2, US" header.from=", header_from_sender);
658 # endif /* SUPPORT_SPF */
659 #endif /* SUPPORT_DMARC */