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)
221 return string_copyn(US rr->data, rr->size);
226 /* dmarc_process adds the envelope sender address to the existing
227 context (if any), retrieves the result, sets up expansion
228 strings and evaluates the condition outcome. */
233 int sr, origin; /* used in SPF section */
234 int dmarc_spf_result = 0; /* stores spf into dmarc conn ctx */
236 pdkim_signature * sig = dkim_signatures;
238 BOOL has_dmarc_record = TRUE;
239 u_char **ruf; /* forensic report addressees, if called for */
241 /* ACLs have "control=dmarc_disable_verify" */
242 if (f.dmarc_disable_verify)
245 /* Store the header From: sender domain for this part of DMARC.
246 * If there is no from_header struct, then it's likely this message
247 * is locally generated and relying on fixups to add it. Just skip
248 * the entire DMARC system if we can't find a From: header....or if
249 * there was a previous error.
253 DEBUG(D_receive) debug_printf("DMARC: no From: header\n");
256 else if (!dmarc_abort)
263 f.parse_allow_group = TRUE;
264 p = parse_find_address_end(from_header->text, FALSE);
265 saveend = *p; *p = '\0';
266 if ((header_from_sender = parse_extract_address(from_header->text, &errormsg,
267 &dummy, &dummy, &domain, FALSE)))
268 header_from_sender += domain;
271 /* The opendmarc library extracts the domain from the email address, but
272 * only try to store it if it's not empty. Otherwise, skip out of DMARC. */
273 if (!header_from_sender || (strcmp( CCS header_from_sender, "") == 0))
275 libdm_status = dmarc_abort
277 : opendmarc_policy_store_from_domain(dmarc_pctx, header_from_sender);
278 if (libdm_status != DMARC_PARSE_OKAY)
280 log_write(0, LOG_MAIN|LOG_PANIC,
281 "failure to store header From: in DMARC: %s, header was '%s'",
282 opendmarc_policy_status_to_str(libdm_status), from_header->text);
287 /* Skip DMARC if connection is SMTP Auth. Temporarily, admin should
288 * instead do this in the ACLs. */
289 if (!dmarc_abort && !sender_host_authenticated)
291 uschar * dmarc_domain;
293 /* Use the envelope sender domain for this part of DMARC */
294 spf_sender_domain = expand_string(US"$sender_address_domain");
297 /* No spf data means null envelope sender so generate a domain name
298 * from the sender_helo_name */
299 if (!spf_sender_domain)
301 spf_sender_domain = sender_helo_name;
302 log_write(0, LOG_MAIN, "DMARC using synthesized SPF sender domain = %s\n",
305 debug_printf("DMARC using synthesized SPF sender domain = %s\n",
308 dmarc_spf_result = DMARC_POLICY_SPF_OUTCOME_NONE;
309 dmarc_spf_ares_result = ARES_RESULT_UNKNOWN;
310 origin = DMARC_POLICY_SPF_ORIGIN_HELO;
311 spf_human_readable = US"";
315 sr = spf_response->result;
316 dmarc_spf_result = sr == SPF_RESULT_NEUTRAL ? DMARC_POLICY_SPF_OUTCOME_NONE :
317 sr == SPF_RESULT_PASS ? DMARC_POLICY_SPF_OUTCOME_PASS :
318 sr == SPF_RESULT_FAIL ? DMARC_POLICY_SPF_OUTCOME_FAIL :
319 sr == SPF_RESULT_SOFTFAIL ? DMARC_POLICY_SPF_OUTCOME_TMPFAIL :
320 DMARC_POLICY_SPF_OUTCOME_NONE;
321 dmarc_spf_ares_result = sr == SPF_RESULT_NEUTRAL ? ARES_RESULT_NEUTRAL :
322 sr == SPF_RESULT_PASS ? ARES_RESULT_PASS :
323 sr == SPF_RESULT_FAIL ? ARES_RESULT_FAIL :
324 sr == SPF_RESULT_SOFTFAIL ? ARES_RESULT_SOFTFAIL :
325 sr == SPF_RESULT_NONE ? ARES_RESULT_NONE :
326 sr == SPF_RESULT_TEMPERROR ? ARES_RESULT_TEMPERROR :
327 sr == SPF_RESULT_PERMERROR ? ARES_RESULT_PERMERROR :
329 origin = DMARC_POLICY_SPF_ORIGIN_MAILFROM;
330 spf_human_readable = US spf_response->header_comment;
332 debug_printf("DMARC using SPF sender domain = %s\n", spf_sender_domain);
334 if (strcmp( CCS spf_sender_domain, "") == 0)
338 libdm_status = opendmarc_policy_store_spf(dmarc_pctx, spf_sender_domain,
339 dmarc_spf_result, origin, spf_human_readable);
340 if (libdm_status != DMARC_PARSE_OKAY)
341 log_write(0, LOG_MAIN|LOG_PANIC, "failure to store spf for DMARC: %s",
342 opendmarc_policy_status_to_str(libdm_status));
345 /* Now we cycle through the dkim signature results and put into
346 * the opendmarc context, further building the DMARC reply. */
347 dkim_history_buffer = US"";
350 int dkim_result, dkim_ares_result, vs, ves;
352 vs = sig->verify_status & ~PDKIM_VERIFY_POLICY;
353 ves = sig->verify_ext_status;
354 dkim_result = vs == PDKIM_VERIFY_PASS ? DMARC_POLICY_DKIM_OUTCOME_PASS :
355 vs == PDKIM_VERIFY_FAIL ? DMARC_POLICY_DKIM_OUTCOME_FAIL :
356 vs == PDKIM_VERIFY_INVALID ? DMARC_POLICY_DKIM_OUTCOME_TMPFAIL :
357 DMARC_POLICY_DKIM_OUTCOME_NONE;
358 libdm_status = opendmarc_policy_store_dkim(dmarc_pctx, US sig->domain,
361 debug_printf("DMARC adding DKIM sender domain = %s\n", sig->domain);
362 if (libdm_status != DMARC_PARSE_OKAY)
363 log_write(0, LOG_MAIN|LOG_PANIC,
364 "failure to store dkim (%s) for DMARC: %s",
365 sig->domain, opendmarc_policy_status_to_str(libdm_status));
368 vs == PDKIM_VERIFY_PASS ? ARES_RESULT_PASS :
369 vs == PDKIM_VERIFY_FAIL ? ARES_RESULT_FAIL :
370 vs == PDKIM_VERIFY_NONE ? ARES_RESULT_NONE :
371 vs == PDKIM_VERIFY_INVALID ?
372 ves == PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE ? ARES_RESULT_PERMERROR :
373 ves == PDKIM_VERIFY_INVALID_BUFFER_SIZE ? ARES_RESULT_PERMERROR :
374 ves == PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD ? ARES_RESULT_PERMERROR :
375 ves == PDKIM_VERIFY_INVALID_PUBKEY_IMPORT ? ARES_RESULT_PERMERROR :
376 ARES_RESULT_UNKNOWN :
378 dkim_history_buffer = string_sprintf("%sdkim %s %d\n", dkim_history_buffer,
379 sig->domain, dkim_ares_result);
383 /* Look up DMARC policy record in DNS. We do this explicitly, rather than
384 letting the dmarc library do it with opendmarc_policy_query_dmarc(), so that
385 our dns access path is used for debug tracing and for the testsuite
388 libdm_status = (rr = dmarc_dns_lookup(header_from_sender))
389 ? opendmarc_policy_store_dmarc(dmarc_pctx, rr, header_from_sender, NULL)
390 : DMARC_DNS_ERROR_NO_RECORD;
391 switch (libdm_status)
393 case DMARC_DNS_ERROR_NXDOMAIN:
394 case DMARC_DNS_ERROR_NO_RECORD:
396 debug_printf("DMARC no record found for %s\n", header_from_sender);
397 has_dmarc_record = FALSE;
399 case DMARC_PARSE_OKAY:
401 debug_printf("DMARC record found for %s\n", header_from_sender);
403 case DMARC_PARSE_ERROR_BAD_VALUE:
405 debug_printf("DMARC record parse error for %s\n", header_from_sender);
406 has_dmarc_record = FALSE;
409 /* everything else, skip dmarc */
411 debug_printf("DMARC skipping (%d), unsure what to do with %s",
412 libdm_status, from_header->text);
413 has_dmarc_record = FALSE;
417 /* Store the policy string in an expandable variable. */
419 libdm_status = opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
420 for (c = 0; dmarc_policy_description[c].name; c++)
421 if (tmp_ans == dmarc_policy_description[c].value)
423 dmarc_domain_policy = string_sprintf("%s",dmarc_policy_description[c].name);
427 /* Can't use exim's string manipulation functions so allocate memory
428 for libopendmarc using its max hostname length definition. */
430 dmarc_domain = store_get(DMARC_MAXHOSTNAMELEN, TRUE);
431 libdm_status = opendmarc_policy_fetch_utilized_domain(dmarc_pctx,
432 dmarc_domain, DMARC_MAXHOSTNAMELEN-1);
433 store_release_above(dmarc_domain + Ustrlen(dmarc_domain)+1);
434 dmarc_used_domain = dmarc_domain;
436 if (libdm_status != DMARC_PARSE_OKAY)
437 log_write(0, LOG_MAIN|LOG_PANIC,
438 "failure to read domainname used for DMARC lookup: %s",
439 opendmarc_policy_status_to_str(libdm_status));
441 dmarc_policy = libdm_status = opendmarc_get_policy_to_enforce(dmarc_pctx);
444 case DMARC_POLICY_ABSENT: /* No DMARC record found */
445 dmarc_status = US"norecord";
446 dmarc_pass_fail = US"none";
447 dmarc_status_text = US"No DMARC record";
448 action = DMARC_RESULT_ACCEPT;
450 case DMARC_FROM_DOMAIN_ABSENT: /* No From: domain */
451 dmarc_status = US"nofrom";
452 dmarc_pass_fail = US"temperror";
453 dmarc_status_text = US"No From: domain found";
454 action = DMARC_RESULT_ACCEPT;
456 case DMARC_POLICY_NONE: /* Accept and report */
457 dmarc_status = US"none";
458 dmarc_pass_fail = US"none";
459 dmarc_status_text = US"None, Accept";
460 action = DMARC_RESULT_ACCEPT;
462 case DMARC_POLICY_PASS: /* Explicit accept */
463 dmarc_status = US"accept";
464 dmarc_pass_fail = US"pass";
465 dmarc_status_text = US"Accept";
466 action = DMARC_RESULT_ACCEPT;
468 case DMARC_POLICY_REJECT: /* Explicit reject */
469 dmarc_status = US"reject";
470 dmarc_pass_fail = US"fail";
471 dmarc_status_text = US"Reject";
472 action = DMARC_RESULT_REJECT;
474 case DMARC_POLICY_QUARANTINE: /* Explicit quarantine */
475 dmarc_status = US"quarantine";
476 dmarc_pass_fail = US"fail";
477 dmarc_status_text = US"Quarantine";
478 action = DMARC_RESULT_QUARANTINE;
481 dmarc_status = US"temperror";
482 dmarc_pass_fail = US"temperror";
483 dmarc_status_text = US"Internal Policy Error";
484 action = DMARC_RESULT_TEMPFAIL;
488 libdm_status = opendmarc_policy_fetch_alignment(dmarc_pctx, &da, &sa);
489 if (libdm_status != DMARC_PARSE_OKAY)
490 log_write(0, LOG_MAIN|LOG_PANIC, "failure to read DMARC alignment: %s",
491 opendmarc_policy_status_to_str(libdm_status));
493 if (has_dmarc_record)
495 log_write(0, LOG_MAIN, "DMARC results: spf_domain=%s dmarc_domain=%s "
496 "spf_align=%s dkim_align=%s enforcement='%s'",
497 spf_sender_domain, dmarc_used_domain,
498 sa==DMARC_POLICY_SPF_ALIGNMENT_PASS ?"yes":"no",
499 da==DMARC_POLICY_DKIM_ALIGNMENT_PASS ?"yes":"no",
501 history_file_status = dmarc_write_history_file();
502 /* Now get the forensic reporting addresses, if any */
503 ruf = opendmarc_policy_fetch_ruf(dmarc_pctx, NULL, 0, 1);
504 dmarc_send_forensic_report(ruf);
508 /* shut down libopendmarc */
510 (void) opendmarc_policy_connect_shutdown(dmarc_pctx);
511 if (!f.dmarc_disable_verify)
512 (void) opendmarc_policy_library_shutdown(&dmarc_ctx);
518 dmarc_write_history_file()
523 u_char **rua; /* aggregate report addressees */
524 uschar *history_buffer = NULL;
526 if (!dmarc_history_file)
528 DEBUG(D_receive) debug_printf("DMARC history file not set\n");
529 return DMARC_HIST_DISABLED;
531 history_file_fd = log_create(dmarc_history_file);
533 if (history_file_fd < 0)
535 log_write(0, LOG_MAIN|LOG_PANIC, "failure to create DMARC history file: %s",
537 return DMARC_HIST_FILE_ERR;
540 /* Generate the contents of the history file */
541 history_buffer = string_sprintf(
542 "job %s\nreporter %s\nreceived %ld\nipaddr %s\nfrom %s\nmfrom %s\n",
543 message_id, primary_hostname, time(NULL), sender_host_address,
544 header_from_sender, expand_string(US"$sender_address_domain"));
547 history_buffer = string_sprintf("%sspf %d\n", history_buffer, dmarc_spf_ares_result);
548 /* history_buffer = string_sprintf("%sspf -1\n", history_buffer); */
550 history_buffer = string_sprintf(
551 "%s%spdomain %s\npolicy %d\n",
552 history_buffer, dkim_history_buffer, dmarc_used_domain, dmarc_policy);
554 if ((rua = opendmarc_policy_fetch_rua(dmarc_pctx, NULL, 0, 1)))
555 for (tmp_ans = 0; rua[tmp_ans]; tmp_ans++)
556 history_buffer = string_sprintf("%srua %s\n", history_buffer, rua[tmp_ans]);
558 history_buffer = string_sprintf("%srua -\n", history_buffer);
560 opendmarc_policy_fetch_pct(dmarc_pctx, &tmp_ans);
561 history_buffer = string_sprintf("%spct %d\n", history_buffer, tmp_ans);
563 opendmarc_policy_fetch_adkim(dmarc_pctx, &tmp_ans);
564 history_buffer = string_sprintf("%sadkim %d\n", history_buffer, tmp_ans);
566 opendmarc_policy_fetch_aspf(dmarc_pctx, &tmp_ans);
567 history_buffer = string_sprintf("%saspf %d\n", history_buffer, tmp_ans);
569 opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
570 history_buffer = string_sprintf("%sp %d\n", history_buffer, tmp_ans);
572 opendmarc_policy_fetch_sp(dmarc_pctx, &tmp_ans);
573 history_buffer = string_sprintf("%ssp %d\n", history_buffer, tmp_ans);
575 history_buffer = string_sprintf(
576 "%salign_dkim %d\nalign_spf %d\naction %d\n",
577 history_buffer, da, sa, action);
579 /* Write the contents to the history file */
581 debug_printf("DMARC logging history data for opendmarc reporting%s\n",
582 (host_checking || f.running_in_test_harness) ? " (not really)" : "");
583 if (host_checking || f.running_in_test_harness)
586 debug_printf("DMARC history data for debugging:\n%s", history_buffer);
590 written_len = write_to_fd_buf(history_file_fd,
592 Ustrlen(history_buffer));
593 if (written_len == 0)
595 log_write(0, LOG_MAIN|LOG_PANIC, "failure to write to DMARC history file: %s",
597 return DMARC_HIST_WRITE_ERR;
599 (void)close(history_file_fd);
601 return DMARC_HIST_OK;
606 dmarc_exim_expand_query(int what)
608 if (f.dmarc_disable_verify || !dmarc_pctx)
609 return dmarc_exim_expand_defaults(what);
611 if (what == DMARC_VERIFY_STATUS)
617 dmarc_exim_expand_defaults(int what)
619 if (what == DMARC_VERIFY_STATUS)
620 return f.dmarc_disable_verify ? US"off" : US"none";
626 authres_dmarc(gstring * g)
628 if (f.dmarc_has_been_checked)
630 g = string_append(g, 2, US";\n\tdmarc=", dmarc_pass_fail);
631 if (header_from_sender)
632 g = string_append(g, 2, US" header.from=", header_from_sender);
637 # endif /* SUPPORT_SPF */
638 #endif /* SUPPORT_DMARC */