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 */
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_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 (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));
115 DEBUG(D_receive) debug_printf("DMARC: no dmarc_tld_file\n");
118 else if (opendmarc_tld_read_file(dmarc_tld_file, NULL, NULL, NULL))
120 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list %s: %d",
121 dmarc_tld_file, 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 (!dmarc_disable_verify)
159 dmarc_send_forensic_report(u_char **ruf)
162 uschar *recipient, *save_sender;
163 BOOL send_status = FALSE;
164 error_block *eblock = NULL;
165 FILE *message_file = NULL;
167 /* Earlier ACL does not have *required* control=dmarc_enable_forensic */
168 if (!dmarc_enable_forensic)
171 if ( dmarc_policy == DMARC_POLICY_REJECT && action == DMARC_RESULT_REJECT
172 || dmarc_policy == DMARC_POLICY_QUARANTINE && action == DMARC_RESULT_QUARANTINE
173 || dmarc_policy == DMARC_POLICY_NONE && action == DMARC_RESULT_REJECT
174 || dmarc_policy == DMARC_POLICY_NONE && action == DMARC_RESULT_QUARANTINE
178 eblock = add_to_eblock(eblock, US"Sender Domain", dmarc_used_domain);
179 eblock = add_to_eblock(eblock, US"Sender IP Address", sender_host_address);
180 eblock = add_to_eblock(eblock, US"Received Date", tod_stamp(tod_full));
181 eblock = add_to_eblock(eblock, US"SPF Alignment",
182 (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?US"yes":US"no");
183 eblock = add_to_eblock(eblock, US"DKIM Alignment",
184 (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?US"yes":US"no");
185 eblock = add_to_eblock(eblock, US"DMARC Results", dmarc_status_text);
186 /* Set a sane default envelope sender */
187 dsn_from = dmarc_forensic_sender ? dmarc_forensic_sender :
188 dsn_from ? dsn_from :
189 string_sprintf("do-not-reply@%s",primary_hostname);
190 for (c = 0; ruf[c]; c++)
192 recipient = string_copylc(ruf[c]);
193 if (Ustrncmp(recipient, "mailto:",7))
195 /* Move to first character past the colon */
198 debug_printf("DMARC forensic report to %s%s\n", recipient,
199 (host_checking || running_in_test_harness) ? " (not really)" : "");
200 if (host_checking || running_in_test_harness)
203 save_sender = sender_address;
204 sender_address = recipient;
205 send_status = moan_to_sender(ERRMESS_DMARC_FORENSIC, eblock,
206 header_list, message_file, FALSE);
207 sender_address = save_sender;
209 log_write(0, LOG_MAIN|LOG_PANIC,
210 "failure to send DMARC forensic report to %s", recipient);
215 /* dmarc_process adds the envelope sender address to the existing
216 context (if any), retrieves the result, sets up expansion
217 strings and evaluates the condition outcome. */
222 int sr, origin; /* used in SPF section */
223 int dmarc_spf_result = 0; /* stores spf into dmarc conn ctx */
225 pdkim_signature *sig = NULL;
226 BOOL has_dmarc_record = TRUE;
227 u_char **ruf; /* forensic report addressees, if called for */
229 /* ACLs have "control=dmarc_disable_verify" */
230 if (dmarc_disable_verify)
233 /* Store the header From: sender domain for this part of DMARC.
234 * If there is no from_header struct, then it's likely this message
235 * is locally generated and relying on fixups to add it. Just skip
236 * the entire DMARC system if we can't find a From: header....or if
237 * there was a previous error.
241 DEBUG(D_receive) debug_printf("DMARC: no From: header\n");
244 else if (!dmarc_abort)
251 parse_allow_group = TRUE;
252 p = parse_find_address_end(from_header->text, FALSE);
253 saveend = *p; *p = '\0';
254 if ((header_from_sender = parse_extract_address(from_header->text, &errormsg,
255 &dummy, &dummy, &domain, FALSE)))
256 header_from_sender += domain;
259 /* The opendmarc library extracts the domain from the email address, but
260 * only try to store it if it's not empty. Otherwise, skip out of DMARC. */
261 if (!header_from_sender || (strcmp( CCS header_from_sender, "") == 0))
263 libdm_status = dmarc_abort ?
265 opendmarc_policy_store_from_domain(dmarc_pctx, header_from_sender);
266 if (libdm_status != DMARC_PARSE_OKAY)
268 log_write(0, LOG_MAIN|LOG_PANIC,
269 "failure to store header From: in DMARC: %s, header was '%s'",
270 opendmarc_policy_status_to_str(libdm_status), from_header->text);
275 /* Skip DMARC if connection is SMTP Auth. Temporarily, admin should
276 * instead do this in the ACLs. */
277 if (!dmarc_abort && !sender_host_authenticated)
279 /* Use the envelope sender domain for this part of DMARC */
280 spf_sender_domain = expand_string(US"$sender_address_domain");
283 /* No spf data means null envelope sender so generate a domain name
284 * from the sender_helo_name */
285 if (!spf_sender_domain)
287 spf_sender_domain = sender_helo_name;
288 log_write(0, LOG_MAIN, "DMARC using synthesized SPF sender domain = %s\n",
291 debug_printf("DMARC using synthesized SPF sender domain = %s\n",
294 dmarc_spf_result = DMARC_POLICY_SPF_OUTCOME_NONE;
295 dmarc_spf_ares_result = ARES_RESULT_UNKNOWN;
296 origin = DMARC_POLICY_SPF_ORIGIN_HELO;
297 spf_human_readable = US"";
301 sr = spf_response->result;
302 dmarc_spf_result = sr == SPF_RESULT_NEUTRAL ? DMARC_POLICY_SPF_OUTCOME_NONE :
303 sr == SPF_RESULT_PASS ? DMARC_POLICY_SPF_OUTCOME_PASS :
304 sr == SPF_RESULT_FAIL ? DMARC_POLICY_SPF_OUTCOME_FAIL :
305 sr == SPF_RESULT_SOFTFAIL ? DMARC_POLICY_SPF_OUTCOME_TMPFAIL :
306 DMARC_POLICY_SPF_OUTCOME_NONE;
307 dmarc_spf_ares_result = sr == SPF_RESULT_NEUTRAL ? ARES_RESULT_NEUTRAL :
308 sr == SPF_RESULT_PASS ? ARES_RESULT_PASS :
309 sr == SPF_RESULT_FAIL ? ARES_RESULT_FAIL :
310 sr == SPF_RESULT_SOFTFAIL ? ARES_RESULT_SOFTFAIL :
311 sr == SPF_RESULT_NONE ? ARES_RESULT_NONE :
312 sr == SPF_RESULT_TEMPERROR ? ARES_RESULT_TEMPERROR :
313 sr == SPF_RESULT_PERMERROR ? ARES_RESULT_PERMERROR :
315 origin = DMARC_POLICY_SPF_ORIGIN_MAILFROM;
316 spf_human_readable = US spf_response->header_comment;
318 debug_printf("DMARC using SPF sender domain = %s\n", spf_sender_domain);
320 if (strcmp( CCS spf_sender_domain, "") == 0)
324 libdm_status = opendmarc_policy_store_spf(dmarc_pctx, spf_sender_domain,
325 dmarc_spf_result, origin, spf_human_readable);
326 if (libdm_status != DMARC_PARSE_OKAY)
327 log_write(0, LOG_MAIN|LOG_PANIC, "failure to store spf for DMARC: %s",
328 opendmarc_policy_status_to_str(libdm_status));
331 /* Now we cycle through the dkim signature results and put into
332 * the opendmarc context, further building the DMARC reply. */
333 sig = dkim_signatures;
334 dkim_history_buffer = US"";
337 int dkim_result, dkim_ares_result, vs, ves;
338 vs = sig->verify_status & ~PDKIM_VERIFY_POLICY;
339 ves = sig->verify_ext_status;
340 dkim_result = vs == PDKIM_VERIFY_PASS ? DMARC_POLICY_DKIM_OUTCOME_PASS :
341 vs == PDKIM_VERIFY_FAIL ? DMARC_POLICY_DKIM_OUTCOME_FAIL :
342 vs == PDKIM_VERIFY_INVALID ? DMARC_POLICY_DKIM_OUTCOME_TMPFAIL :
343 DMARC_POLICY_DKIM_OUTCOME_NONE;
344 libdm_status = opendmarc_policy_store_dkim(dmarc_pctx, US sig->domain,
347 debug_printf("DMARC adding DKIM sender domain = %s\n", sig->domain);
348 if (libdm_status != DMARC_PARSE_OKAY)
349 log_write(0, LOG_MAIN|LOG_PANIC,
350 "failure to store dkim (%s) for DMARC: %s",
351 sig->domain, opendmarc_policy_status_to_str(libdm_status));
354 vs == PDKIM_VERIFY_PASS ? ARES_RESULT_PASS :
355 vs == PDKIM_VERIFY_FAIL ? ARES_RESULT_FAIL :
356 vs == PDKIM_VERIFY_NONE ? ARES_RESULT_NONE :
357 vs == PDKIM_VERIFY_INVALID ?
358 ves == PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE ? ARES_RESULT_PERMERROR :
359 ves == PDKIM_VERIFY_INVALID_BUFFER_SIZE ? ARES_RESULT_PERMERROR :
360 ves == PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD ? ARES_RESULT_PERMERROR :
361 ves == PDKIM_VERIFY_INVALID_PUBKEY_IMPORT ? ARES_RESULT_PERMERROR :
362 ARES_RESULT_UNKNOWN :
364 dkim_history_buffer = string_sprintf("%sdkim %s %d\n", dkim_history_buffer,
365 sig->domain, dkim_ares_result);
368 libdm_status = opendmarc_policy_query_dmarc(dmarc_pctx, US"");
369 switch (libdm_status)
371 case DMARC_DNS_ERROR_NXDOMAIN:
372 case DMARC_DNS_ERROR_NO_RECORD:
374 debug_printf("DMARC no record found for %s\n", header_from_sender);
375 has_dmarc_record = FALSE;
377 case DMARC_PARSE_OKAY:
379 debug_printf("DMARC record found for %s\n", header_from_sender);
381 case DMARC_PARSE_ERROR_BAD_VALUE:
383 debug_printf("DMARC record parse error for %s\n", header_from_sender);
384 has_dmarc_record = FALSE;
387 /* everything else, skip dmarc */
389 debug_printf("DMARC skipping (%d), unsure what to do with %s",
390 libdm_status, from_header->text);
391 has_dmarc_record = FALSE;
395 /* Store the policy string in an expandable variable. */
397 libdm_status = opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
398 for (c = 0; dmarc_policy_description[c].name; c++)
399 if (tmp_ans == dmarc_policy_description[c].value)
401 dmarc_domain_policy = string_sprintf("%s",dmarc_policy_description[c].name);
405 /* Can't use exim's string manipulation functions so allocate memory
406 * for libopendmarc using its max hostname length definition. */
408 uschar *dmarc_domain = US calloc(DMARC_MAXHOSTNAMELEN, sizeof(uschar));
409 libdm_status = opendmarc_policy_fetch_utilized_domain(dmarc_pctx,
410 dmarc_domain, DMARC_MAXHOSTNAMELEN-1);
411 dmarc_used_domain = string_copy(dmarc_domain);
414 if (libdm_status != DMARC_PARSE_OKAY)
415 log_write(0, LOG_MAIN|LOG_PANIC,
416 "failure to read domainname used for DMARC lookup: %s",
417 opendmarc_policy_status_to_str(libdm_status));
419 libdm_status = opendmarc_get_policy_to_enforce(dmarc_pctx);
420 dmarc_policy = libdm_status;
423 case DMARC_POLICY_ABSENT: /* No DMARC record found */
424 dmarc_status = US"norecord";
425 dmarc_pass_fail = US"none";
426 dmarc_status_text = US"No DMARC record";
427 action = DMARC_RESULT_ACCEPT;
429 case DMARC_FROM_DOMAIN_ABSENT: /* No From: domain */
430 dmarc_status = US"nofrom";
431 dmarc_pass_fail = US"temperror";
432 dmarc_status_text = US"No From: domain found";
433 action = DMARC_RESULT_ACCEPT;
435 case DMARC_POLICY_NONE: /* Accept and report */
436 dmarc_status = US"none";
437 dmarc_pass_fail = US"none";
438 dmarc_status_text = US"None, Accept";
439 action = DMARC_RESULT_ACCEPT;
441 case DMARC_POLICY_PASS: /* Explicit accept */
442 dmarc_status = US"accept";
443 dmarc_pass_fail = US"pass";
444 dmarc_status_text = US"Accept";
445 action = DMARC_RESULT_ACCEPT;
447 case DMARC_POLICY_REJECT: /* Explicit reject */
448 dmarc_status = US"reject";
449 dmarc_pass_fail = US"fail";
450 dmarc_status_text = US"Reject";
451 action = DMARC_RESULT_REJECT;
453 case DMARC_POLICY_QUARANTINE: /* Explicit quarantine */
454 dmarc_status = US"quarantine";
455 dmarc_pass_fail = US"fail";
456 dmarc_status_text = US"Quarantine";
457 action = DMARC_RESULT_QUARANTINE;
460 dmarc_status = US"temperror";
461 dmarc_pass_fail = US"temperror";
462 dmarc_status_text = US"Internal Policy Error";
463 action = DMARC_RESULT_TEMPFAIL;
467 libdm_status = opendmarc_policy_fetch_alignment(dmarc_pctx, &da, &sa);
468 if (libdm_status != DMARC_PARSE_OKAY)
469 log_write(0, LOG_MAIN|LOG_PANIC, "failure to read DMARC alignment: %s",
470 opendmarc_policy_status_to_str(libdm_status));
472 if (has_dmarc_record)
474 log_write(0, LOG_MAIN, "DMARC results: spf_domain=%s dmarc_domain=%s "
475 "spf_align=%s dkim_align=%s enforcement='%s'",
476 spf_sender_domain, dmarc_used_domain,
477 (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?"yes":"no",
478 (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?"yes":"no",
480 history_file_status = dmarc_write_history_file();
481 /* Now get the forensic reporting addresses, if any */
482 ruf = opendmarc_policy_fetch_ruf(dmarc_pctx, NULL, 0, 1);
483 dmarc_send_forensic_report(ruf);
487 /* shut down libopendmarc */
489 (void) opendmarc_policy_connect_shutdown(dmarc_pctx);
490 if (!dmarc_disable_verify)
491 (void) opendmarc_policy_library_shutdown(&dmarc_ctx);
497 dmarc_write_history_file()
502 u_char **rua; /* aggregate report addressees */
503 uschar *history_buffer = NULL;
505 if (!dmarc_history_file)
506 return DMARC_HIST_DISABLED;
507 history_file_fd = log_create(dmarc_history_file);
509 if (history_file_fd < 0)
511 log_write(0, LOG_MAIN|LOG_PANIC, "failure to create DMARC history file: %s",
513 return DMARC_HIST_FILE_ERR;
516 /* Generate the contents of the history file */
517 history_buffer = string_sprintf(
518 "job %s\nreporter %s\nreceived %ld\nipaddr %s\nfrom %s\nmfrom %s\n",
519 message_id, primary_hostname, time(NULL), sender_host_address,
520 header_from_sender, expand_string(US"$sender_address_domain"));
523 history_buffer = string_sprintf("%sspf %d\n", history_buffer, dmarc_spf_ares_result);
524 /* history_buffer = string_sprintf("%sspf -1\n", history_buffer); */
526 history_buffer = string_sprintf(
527 "%s%spdomain %s\npolicy %d\n",
528 history_buffer, dkim_history_buffer, dmarc_used_domain, dmarc_policy);
530 if ((rua = opendmarc_policy_fetch_rua(dmarc_pctx, NULL, 0, 1)))
531 for (tmp_ans = 0; rua[tmp_ans]; tmp_ans++)
532 history_buffer = string_sprintf("%srua %s\n", history_buffer, rua[tmp_ans]);
534 history_buffer = string_sprintf("%srua -\n", history_buffer);
536 opendmarc_policy_fetch_pct(dmarc_pctx, &tmp_ans);
537 history_buffer = string_sprintf("%spct %d\n", history_buffer, tmp_ans);
539 opendmarc_policy_fetch_adkim(dmarc_pctx, &tmp_ans);
540 history_buffer = string_sprintf("%sadkim %d\n", history_buffer, tmp_ans);
542 opendmarc_policy_fetch_aspf(dmarc_pctx, &tmp_ans);
543 history_buffer = string_sprintf("%saspf %d\n", history_buffer, tmp_ans);
545 opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
546 history_buffer = string_sprintf("%sp %d\n", history_buffer, tmp_ans);
548 opendmarc_policy_fetch_sp(dmarc_pctx, &tmp_ans);
549 history_buffer = string_sprintf("%ssp %d\n", history_buffer, tmp_ans);
551 history_buffer = string_sprintf(
552 "%salign_dkim %d\nalign_spf %d\naction %d\n",
553 history_buffer, da, sa, action);
555 /* Write the contents to the history file */
557 debug_printf("DMARC logging history data for opendmarc reporting%s\n",
558 (host_checking || running_in_test_harness) ? " (not really)" : "");
559 if (host_checking || running_in_test_harness)
562 debug_printf("DMARC history data for debugging:\n%s", history_buffer);
566 written_len = write_to_fd_buf(history_file_fd,
568 Ustrlen(history_buffer));
569 if (written_len == 0)
571 log_write(0, LOG_MAIN|LOG_PANIC, "failure to write to DMARC history file: %s",
573 return DMARC_HIST_WRITE_ERR;
575 (void)close(history_file_fd);
577 return DMARC_HIST_OK;
582 dmarc_exim_expand_query(int what)
584 if (dmarc_disable_verify || !dmarc_pctx)
585 return dmarc_exim_expand_defaults(what);
587 if (what == DMARC_VERIFY_STATUS)
593 dmarc_exim_expand_defaults(int what)
595 if (what == DMARC_VERIFY_STATUS)
596 return dmarc_disable_verify ? US"off" : US"none";
602 authres_dmarc(gstring * g)
604 if (dmarc_has_been_checked)
606 g = string_append(g, 2, US";\n\tdmarc=", dmarc_pass_fail);
607 if (header_from_sender)
608 g = string_append(g, 2, US" header.from=", header_from_sender);
613 # endif /* SUPPORT_SPF */
614 #endif /* EXPERIMENTAL_DMARC */