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 EXPERIMENTAL_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[] = {
47 { US"", DMARC_RECORD_P_UNSPECIFIED },
48 { US"none", DMARC_RECORD_P_NONE },
49 { US"quarantine", DMARC_RECORD_P_QUARANTINE },
50 { US"reject", DMARC_RECORD_P_REJECT },
53 /* Accept an error_block struct, initialize if empty, parse to the
54 * end, and append the two strings passed to it. Used for adding
55 * variable amounts of value:pair data to the forensic emails. */
58 add_to_eblock(error_block *eblock, uschar *t1, uschar *t2)
60 error_block *eb = store_malloc(sizeof(error_block));
65 /* Find the end of the eblock struct and point it at eb */
66 error_block *tmp = eblock;
67 while(tmp->next != NULL)
77 /* dmarc_init sets up a context that can be re-used for several
78 messages on the same SMTP connection (that come from the
79 same host with the same HELO string) */
83 int *netmask = NULL; /* Ignored */
85 char *tld_file = (dmarc_tld_file == NULL) ?
86 DMARC_TLD_FILE : (char *)dmarc_tld_file;
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 dmarc_ar_header = NULL;
96 dmarc_has_been_checked = FALSE;
97 header_from_sender = NULL;
98 spf_sender_domain = NULL;
99 spf_human_readable = NULL;
101 /* ACLs have "control=dmarc_disable_verify" */
102 if (dmarc_disable_verify == TRUE)
105 (void) memset(&dmarc_ctx, '\0', sizeof dmarc_ctx);
106 dmarc_ctx.nscount = 0;
107 libdm_status = opendmarc_policy_library_init(&dmarc_ctx);
108 if (libdm_status != DMARC_PARSE_OKAY)
110 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to init library: %s",
111 opendmarc_policy_status_to_str(libdm_status));
114 if (dmarc_tld_file == NULL)
116 else if (opendmarc_tld_read_file(tld_file, NULL, NULL, NULL))
118 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list %s: %d",
122 if (sender_host_address == NULL)
124 /* This catches locally originated email and startup errors above. */
127 is_ipv6 = string_is_ip_address(sender_host_address, netmask) == 6;
128 dmarc_pctx = opendmarc_policy_connect_init(sender_host_address, is_ipv6);
129 if (dmarc_pctx == NULL)
131 log_write(0, LOG_MAIN|LOG_PANIC,
132 "DMARC failure creating policy context: ip=%s", sender_host_address);
141 /* dmarc_store_data stores the header data so that subsequent
142 * dmarc_process can access the data */
144 int dmarc_store_data(header_line *hdr) {
145 /* No debug output because would change every test debug output */
146 if (dmarc_disable_verify != TRUE)
153 dmarc_send_forensic_report(u_char **ruf)
156 uschar *recipient, *save_sender;
157 BOOL send_status = FALSE;
158 error_block *eblock = NULL;
159 FILE *message_file = NULL;
161 /* Earlier ACL does not have *required* control=dmarc_enable_forensic */
162 if (!dmarc_enable_forensic)
165 if ( dmarc_policy == DMARC_POLICY_REJECT && action == DMARC_RESULT_REJECT
166 || dmarc_policy == DMARC_POLICY_QUARANTINE && action == DMARC_RESULT_QUARANTINE
167 || dmarc_policy == DMARC_POLICY_NONE && action == DMARC_RESULT_REJECT
168 || dmarc_policy == DMARC_POLICY_NONE && action == DMARC_RESULT_QUARANTINE
172 eblock = add_to_eblock(eblock, US"Sender Domain", dmarc_used_domain);
173 eblock = add_to_eblock(eblock, US"Sender IP Address", sender_host_address);
174 eblock = add_to_eblock(eblock, US"Received Date", tod_stamp(tod_full));
175 eblock = add_to_eblock(eblock, US"SPF Alignment",
176 (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?US"yes":US"no");
177 eblock = add_to_eblock(eblock, US"DKIM Alignment",
178 (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?US"yes":US"no");
179 eblock = add_to_eblock(eblock, US"DMARC Results", dmarc_status_text);
180 /* Set a sane default envelope sender */
181 dsn_from = dmarc_forensic_sender ? dmarc_forensic_sender :
182 dsn_from ? dsn_from :
183 string_sprintf("do-not-reply@%s",primary_hostname);
184 for (c = 0; ruf[c]; c++)
186 recipient = string_copylc(ruf[c]);
187 if (Ustrncmp(recipient, "mailto:",7))
189 /* Move to first character past the colon */
192 debug_printf("DMARC forensic report to %s%s\n", recipient,
193 (host_checking || running_in_test_harness) ? " (not really)" : "");
194 if (host_checking || running_in_test_harness)
197 save_sender = sender_address;
198 sender_address = recipient;
199 send_status = moan_to_sender(ERRMESS_DMARC_FORENSIC, eblock,
200 header_list, message_file, FALSE);
201 sender_address = save_sender;
203 log_write(0, LOG_MAIN|LOG_PANIC,
204 "failure to send DMARC forensic report to %s", recipient);
209 /* dmarc_process adds the envelope sender address to the existing
210 context (if any), retrieves the result, sets up expansion
211 strings and evaluates the condition outcome. */
216 int sr, origin; /* used in SPF section */
217 int dmarc_spf_result = 0; /* stores spf into dmarc conn ctx */
219 pdkim_signature *sig = NULL;
220 BOOL has_dmarc_record = TRUE;
221 u_char **ruf; /* forensic report addressees, if called for */
223 /* ACLs have "control=dmarc_disable_verify" */
224 if (dmarc_disable_verify)
226 dmarc_ar_header = dmarc_auth_results_header(from_header, NULL);
230 /* Store the header From: sender domain for this part of DMARC.
231 * If there is no from_header struct, then it's likely this message
232 * is locally generated and relying on fixups to add it. Just skip
233 * the entire DMARC system if we can't find a From: header....or if
234 * there was a previous error.
236 if (!from_header || dmarc_abort)
245 parse_allow_group = TRUE;
246 p = parse_find_address_end(from_header->text, FALSE);
247 saveend = *p; *p = '\0';
248 if ((header_from_sender = parse_extract_address(from_header->text, &errormsg,
249 &dummy, &dummy, &domain, FALSE)))
250 header_from_sender += domain;
253 /* The opendmarc library extracts the domain from the email address, but
254 * only try to store it if it's not empty. Otherwise, skip out of DMARC. */
255 if (!header_from_sender || (strcmp( CCS header_from_sender, "") == 0))
257 libdm_status = dmarc_abort ?
259 opendmarc_policy_store_from_domain(dmarc_pctx, header_from_sender);
260 if (libdm_status != DMARC_PARSE_OKAY)
262 log_write(0, LOG_MAIN|LOG_PANIC,
263 "failure to store header From: in DMARC: %s, header was '%s'",
264 opendmarc_policy_status_to_str(libdm_status), from_header->text);
269 /* Skip DMARC if connection is SMTP Auth. Temporarily, admin should
270 * instead do this in the ACLs. */
271 if (!dmarc_abort && !sender_host_authenticated)
273 /* Use the envelope sender domain for this part of DMARC */
274 spf_sender_domain = expand_string(US"$sender_address_domain");
277 /* No spf data means null envelope sender so generate a domain name
278 * from the sender_helo_name */
279 if (!spf_sender_domain)
281 spf_sender_domain = sender_helo_name;
282 log_write(0, LOG_MAIN, "DMARC using synthesized SPF sender domain = %s\n",
285 debug_printf("DMARC using synthesized SPF sender domain = %s\n",
288 dmarc_spf_result = DMARC_POLICY_SPF_OUTCOME_NONE;
289 dmarc_spf_ares_result = ARES_RESULT_UNKNOWN;
290 origin = DMARC_POLICY_SPF_ORIGIN_HELO;
291 spf_human_readable = US"";
295 sr = spf_response->result;
296 dmarc_spf_result = sr == SPF_RESULT_NEUTRAL ? DMARC_POLICY_SPF_OUTCOME_NONE :
297 sr == SPF_RESULT_PASS ? DMARC_POLICY_SPF_OUTCOME_PASS :
298 sr == SPF_RESULT_FAIL ? DMARC_POLICY_SPF_OUTCOME_FAIL :
299 sr == SPF_RESULT_SOFTFAIL ? DMARC_POLICY_SPF_OUTCOME_TMPFAIL :
300 DMARC_POLICY_SPF_OUTCOME_NONE;
301 dmarc_spf_ares_result = sr == SPF_RESULT_NEUTRAL ? ARES_RESULT_NEUTRAL :
302 sr == SPF_RESULT_PASS ? ARES_RESULT_PASS :
303 sr == SPF_RESULT_FAIL ? ARES_RESULT_FAIL :
304 sr == SPF_RESULT_SOFTFAIL ? ARES_RESULT_SOFTFAIL :
305 sr == SPF_RESULT_NONE ? ARES_RESULT_NONE :
306 sr == SPF_RESULT_TEMPERROR ? ARES_RESULT_TEMPERROR :
307 sr == SPF_RESULT_PERMERROR ? ARES_RESULT_PERMERROR :
309 origin = DMARC_POLICY_SPF_ORIGIN_MAILFROM;
310 spf_human_readable = (uschar *)spf_response->header_comment;
312 debug_printf("DMARC using SPF sender domain = %s\n", spf_sender_domain);
314 if (strcmp( CCS spf_sender_domain, "") == 0)
318 libdm_status = opendmarc_policy_store_spf(dmarc_pctx, spf_sender_domain,
319 dmarc_spf_result, origin, spf_human_readable);
320 if (libdm_status != DMARC_PARSE_OKAY)
321 log_write(0, LOG_MAIN|LOG_PANIC, "failure to store spf for DMARC: %s",
322 opendmarc_policy_status_to_str(libdm_status));
325 /* Now we cycle through the dkim signature results and put into
326 * the opendmarc context, further building the DMARC reply. */
327 sig = dkim_signatures;
328 dkim_history_buffer = US"";
331 int dkim_result, dkim_ares_result, vs, ves;
332 vs = sig->verify_status;
333 ves = sig->verify_ext_status;
334 dkim_result = vs == PDKIM_VERIFY_PASS ? DMARC_POLICY_DKIM_OUTCOME_PASS :
335 vs == PDKIM_VERIFY_FAIL ? DMARC_POLICY_DKIM_OUTCOME_FAIL :
336 vs == PDKIM_VERIFY_INVALID ? DMARC_POLICY_DKIM_OUTCOME_TMPFAIL :
337 DMARC_POLICY_DKIM_OUTCOME_NONE;
338 libdm_status = opendmarc_policy_store_dkim(dmarc_pctx, (uschar *)sig->domain,
341 debug_printf("DMARC adding DKIM sender domain = %s\n", sig->domain);
342 if (libdm_status != DMARC_PARSE_OKAY)
343 log_write(0, LOG_MAIN|LOG_PANIC,
344 "failure to store dkim (%s) for DMARC: %s",
345 sig->domain, opendmarc_policy_status_to_str(libdm_status));
348 vs == PDKIM_VERIFY_PASS ? ARES_RESULT_PASS :
349 vs == PDKIM_VERIFY_FAIL ? ARES_RESULT_FAIL :
350 vs == PDKIM_VERIFY_NONE ? ARES_RESULT_NONE :
351 vs == PDKIM_VERIFY_INVALID ?
352 ves == PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE ? ARES_RESULT_PERMERROR :
353 ves == PDKIM_VERIFY_INVALID_BUFFER_SIZE ? ARES_RESULT_PERMERROR :
354 ves == PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD ? ARES_RESULT_PERMERROR :
355 ves == PDKIM_VERIFY_INVALID_PUBKEY_IMPORT ? ARES_RESULT_PERMERROR :
356 ARES_RESULT_UNKNOWN :
358 dkim_history_buffer = string_sprintf("%sdkim %s %d\n", dkim_history_buffer,
359 sig->domain, dkim_ares_result);
362 libdm_status = opendmarc_policy_query_dmarc(dmarc_pctx, US"");
363 switch (libdm_status)
365 case DMARC_DNS_ERROR_NXDOMAIN:
366 case DMARC_DNS_ERROR_NO_RECORD:
368 debug_printf("DMARC no record found for %s\n", header_from_sender);
369 has_dmarc_record = FALSE;
371 case DMARC_PARSE_OKAY:
373 debug_printf("DMARC record found for %s\n", header_from_sender);
375 case DMARC_PARSE_ERROR_BAD_VALUE:
377 debug_printf("DMARC record parse error for %s\n", header_from_sender);
378 has_dmarc_record = FALSE;
381 /* everything else, skip dmarc */
383 debug_printf("DMARC skipping (%d), unsure what to do with %s",
384 libdm_status, from_header->text);
385 has_dmarc_record = FALSE;
389 /* Store the policy string in an expandable variable. */
391 libdm_status = opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
392 for (c = 0; dmarc_policy_description[c].name; c++)
393 if (tmp_ans == dmarc_policy_description[c].value)
395 dmarc_domain_policy = string_sprintf("%s",dmarc_policy_description[c].name);
399 /* Can't use exim's string manipulation functions so allocate memory
400 * for libopendmarc using its max hostname length definition. */
402 uschar *dmarc_domain = (uschar *)calloc(DMARC_MAXHOSTNAMELEN, sizeof(uschar));
403 libdm_status = opendmarc_policy_fetch_utilized_domain(dmarc_pctx,
404 dmarc_domain, DMARC_MAXHOSTNAMELEN-1);
405 dmarc_used_domain = string_copy(dmarc_domain);
408 if (libdm_status != DMARC_PARSE_OKAY)
409 log_write(0, LOG_MAIN|LOG_PANIC,
410 "failure to read domainname used for DMARC lookup: %s",
411 opendmarc_policy_status_to_str(libdm_status));
413 libdm_status = opendmarc_get_policy_to_enforce(dmarc_pctx);
414 dmarc_policy = libdm_status;
417 case DMARC_POLICY_ABSENT: /* No DMARC record found */
418 dmarc_status = US"norecord";
419 dmarc_pass_fail = US"none";
420 dmarc_status_text = US"No DMARC record";
421 action = DMARC_RESULT_ACCEPT;
423 case DMARC_FROM_DOMAIN_ABSENT: /* No From: domain */
424 dmarc_status = US"nofrom";
425 dmarc_pass_fail = US"temperror";
426 dmarc_status_text = US"No From: domain found";
427 action = DMARC_RESULT_ACCEPT;
429 case DMARC_POLICY_NONE: /* Accept and report */
430 dmarc_status = US"none";
431 dmarc_pass_fail = US"none";
432 dmarc_status_text = US"None, Accept";
433 action = DMARC_RESULT_ACCEPT;
435 case DMARC_POLICY_PASS: /* Explicit accept */
436 dmarc_status = US"accept";
437 dmarc_pass_fail = US"pass";
438 dmarc_status_text = US"Accept";
439 action = DMARC_RESULT_ACCEPT;
441 case DMARC_POLICY_REJECT: /* Explicit reject */
442 dmarc_status = US"reject";
443 dmarc_pass_fail = US"fail";
444 dmarc_status_text = US"Reject";
445 action = DMARC_RESULT_REJECT;
447 case DMARC_POLICY_QUARANTINE: /* Explicit quarantine */
448 dmarc_status = US"quarantine";
449 dmarc_pass_fail = US"fail";
450 dmarc_status_text = US"Quarantine";
451 action = DMARC_RESULT_QUARANTINE;
454 dmarc_status = US"temperror";
455 dmarc_pass_fail = US"temperror";
456 dmarc_status_text = US"Internal Policy Error";
457 action = DMARC_RESULT_TEMPFAIL;
461 libdm_status = opendmarc_policy_fetch_alignment(dmarc_pctx, &da, &sa);
462 if (libdm_status != DMARC_PARSE_OKAY)
463 log_write(0, LOG_MAIN|LOG_PANIC, "failure to read DMARC alignment: %s",
464 opendmarc_policy_status_to_str(libdm_status));
466 if (has_dmarc_record == TRUE)
468 log_write(0, LOG_MAIN, "DMARC results: spf_domain=%s dmarc_domain=%s "
469 "spf_align=%s dkim_align=%s enforcement='%s'",
470 spf_sender_domain, dmarc_used_domain,
471 (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?"yes":"no",
472 (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?"yes":"no",
474 history_file_status = dmarc_write_history_file();
475 /* Now get the forensic reporting addresses, if any */
476 ruf = opendmarc_policy_fetch_ruf(dmarc_pctx, NULL, 0, 1);
477 dmarc_send_forensic_report(ruf);
481 /* set some global variables here */
482 dmarc_ar_header = dmarc_auth_results_header(from_header, NULL);
484 /* shut down libopendmarc */
485 if ( dmarc_pctx != NULL )
486 (void) opendmarc_policy_connect_shutdown(dmarc_pctx);
487 if ( dmarc_disable_verify == FALSE )
488 (void) opendmarc_policy_library_shutdown(&dmarc_ctx);
494 dmarc_write_history_file()
499 u_char **rua; /* aggregate report addressees */
500 uschar *history_buffer = NULL;
502 if (!dmarc_history_file)
503 return DMARC_HIST_DISABLED;
504 history_file_fd = log_create(dmarc_history_file);
506 if (history_file_fd < 0)
508 log_write(0, LOG_MAIN|LOG_PANIC, "failure to create DMARC history file: %s",
510 return DMARC_HIST_FILE_ERR;
513 /* Generate the contents of the history file */
514 history_buffer = string_sprintf(
515 "job %s\nreporter %s\nreceived %ld\nipaddr %s\nfrom %s\nmfrom %s\n",
516 message_id, primary_hostname, time(NULL), sender_host_address,
517 header_from_sender, expand_string(US"$sender_address_domain"));
520 history_buffer = string_sprintf("%sspf %d\n", history_buffer, dmarc_spf_ares_result);
521 /* history_buffer = string_sprintf("%sspf -1\n", history_buffer); */
523 history_buffer = string_sprintf(
524 "%s%spdomain %s\npolicy %d\n",
525 history_buffer, dkim_history_buffer, dmarc_used_domain, dmarc_policy);
527 if ((rua = opendmarc_policy_fetch_rua(dmarc_pctx, NULL, 0, 1)))
528 for (tmp_ans = 0; rua[tmp_ans]; tmp_ans++)
529 history_buffer = string_sprintf("%srua %s\n", history_buffer, rua[tmp_ans]);
531 history_buffer = string_sprintf("%srua -\n", history_buffer);
533 opendmarc_policy_fetch_pct(dmarc_pctx, &tmp_ans);
534 history_buffer = string_sprintf("%spct %d\n", history_buffer, tmp_ans);
536 opendmarc_policy_fetch_adkim(dmarc_pctx, &tmp_ans);
537 history_buffer = string_sprintf("%sadkim %d\n", history_buffer, tmp_ans);
539 opendmarc_policy_fetch_aspf(dmarc_pctx, &tmp_ans);
540 history_buffer = string_sprintf("%saspf %d\n", history_buffer, tmp_ans);
542 opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
543 history_buffer = string_sprintf("%sp %d\n", history_buffer, tmp_ans);
545 opendmarc_policy_fetch_sp(dmarc_pctx, &tmp_ans);
546 history_buffer = string_sprintf("%ssp %d\n", history_buffer, tmp_ans);
548 history_buffer = string_sprintf(
549 "%salign_dkim %d\nalign_spf %d\naction %d\n",
550 history_buffer, da, sa, action);
552 /* Write the contents to the history file */
554 debug_printf("DMARC logging history data for opendmarc reporting%s\n",
555 (host_checking || running_in_test_harness) ? " (not really)" : "");
556 if (host_checking || running_in_test_harness)
559 debug_printf("DMARC history data for debugging:\n%s", history_buffer);
563 written_len = write_to_fd_buf(history_file_fd,
565 Ustrlen(history_buffer));
566 if (written_len == 0)
568 log_write(0, LOG_MAIN|LOG_PANIC, "failure to write to DMARC history file: %s",
570 return DMARC_HIST_WRITE_ERR;
572 (void)close(history_file_fd);
574 return DMARC_HIST_OK;
578 dmarc_exim_expand_query(int what)
580 if (dmarc_disable_verify || !dmarc_pctx)
581 return dmarc_exim_expand_defaults(what);
585 case DMARC_VERIFY_STATUS:
586 return(dmarc_status);
593 dmarc_exim_expand_defaults(int what)
597 case DMARC_VERIFY_STATUS:
598 return dmarc_disable_verify ? US"off" : US"none";
605 dmarc_auth_results_header(header_line *from_header, uschar *hostname)
607 uschar *hdr_tmp = US"";
609 /* Allow a server hostname to be passed to this function, but is
610 * currently unused */
612 hostname = primary_hostname;
613 hdr_tmp = string_sprintf("%s %s;", DMARC_AR_HEADER, hostname);
616 /* I don't think this belongs here, but left it here commented out
617 * because it was a lot of work to get working right. */
618 if (spf_response != NULL) {
619 uschar *dmarc_ar_spf = US"";
621 sr = spf_response->result;
622 dmarc_ar_spf = (sr == SPF_RESULT_NEUTRAL) ? US"neutral" :
623 (sr == SPF_RESULT_PASS) ? US"pass" :
624 (sr == SPF_RESULT_FAIL) ? US"fail" :
625 (sr == SPF_RESULT_SOFTFAIL) ? US"softfail" :
627 hdr_tmp = string_sprintf("%s spf=%s (%s) smtp.mail=%s;",
628 hdr_tmp, dmarc_ar_spf_result,
629 spf_response->header_comment,
630 expand_string(US"$sender_address") );
634 hdr_tmp = string_sprintf("%s dmarc=%s", hdr_tmp, dmarc_pass_fail);
635 if (header_from_sender)
636 hdr_tmp = string_sprintf("%s header.from=%s",
637 hdr_tmp, header_from_sender);
641 # endif /* EXPERIMENTAL_SPF */
642 #endif /* EXPERIMENTAL_DMARC */