1 /*************************************************
2 * Exim - an Internet mail transport agent *
3 *************************************************/
4 /* Experimental DMARC support.
5 Copyright (c) Todd Lyons <tlyons@exim.org> 2012, 2013
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 /* Accept an error_block struct, initialize if empty, parse to the
42 * end, and append the two strings passed to it. Used for adding
43 * variable amounts of value:pair data to the forensic emails. */
46 add_to_eblock(error_block *eblock, uschar *t1, uschar *t2)
48 error_block *eb = malloc(sizeof(error_block));
53 /* Find the end of the eblock struct and point it at eb */
54 error_block *tmp = eblock;
55 while(tmp->next != NULL)
65 /* dmarc_init sets up a context that can be re-used for several
66 messages on the same SMTP connection (that come from the
67 same host with the same HELO string) */
71 int *netmask = NULL; /* Ignored */
73 char *tld_file = (dmarc_tld_file == NULL) ?
74 "/etc/exim/opendmarc.tlds" :
75 (char *)dmarc_tld_file;
77 /* Set some sane defaults. Also clears previous results when
78 * multiple messages in one connection. */
80 dmarc_status = US"none";
82 dmarc_pass_fail = US"skipped";
83 dmarc_used_domain = US"";
84 dmarc_ar_header = NULL;
85 dmarc_has_been_checked = FALSE;
86 header_from_sender = NULL;
87 spf_sender_domain = NULL;
88 spf_human_readable = NULL;
90 /* ACLs have "control=dmarc_disable_verify" */
91 if (dmarc_disable_verify == TRUE)
94 (void) memset(&dmarc_ctx, '\0', sizeof dmarc_ctx);
95 dmarc_ctx.nscount = 0;
96 libdm_status = opendmarc_policy_library_init(&dmarc_ctx);
97 if (libdm_status != DMARC_PARSE_OKAY)
99 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to init library: %s",
100 opendmarc_policy_status_to_str(libdm_status));
103 if (dmarc_tld_file == NULL)
105 else if (opendmarc_tld_read_file(tld_file, NULL, NULL, NULL))
107 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure to load tld list %s: %d",
111 if (sender_host_address == NULL)
113 /* This catches locally originated email and startup errors above. */
114 if ( dmarc_abort == FALSE )
116 is_ipv6 = string_is_ip_address(sender_host_address, netmask);
117 is_ipv6 = (is_ipv6 == 6) ? TRUE :
118 (is_ipv6 == 4) ? FALSE : FALSE;
119 dmarc_pctx = opendmarc_policy_connect_init(sender_host_address, is_ipv6);
120 if (dmarc_pctx == NULL )
122 log_write(0, LOG_MAIN|LOG_PANIC, "DMARC failure creating policy context: ip=%s",
123 sender_host_address);
132 /* dmarc_store_data stores the header data so that subsequent
133 * dmarc_process can access the data */
135 int dmarc_store_data(header_line *hdr) {
136 /* No debug output because would change every test debug output */
137 if (dmarc_disable_verify != TRUE)
143 /* dmarc_process adds the envelope sender address to the existing
144 context (if any), retrieves the result, sets up expansion
145 strings and evaluates the condition outcome. */
147 int dmarc_process() {
148 int sr, origin; /* used in SPF section */
149 int dmarc_spf_result = 0; /* stores spf into dmarc conn ctx */
150 pdkim_signature *sig = NULL;
151 BOOL has_dmarc_record = TRUE;
152 u_char **ruf; /* forensic report addressees, if called for */
154 /* ACLs have "control=dmarc_disable_verify" */
155 if (dmarc_disable_verify == TRUE)
157 dmarc_ar_header = dmarc_auth_results_header(from_header, NULL);
161 /* Store the header From: sender domain for this part of DMARC.
162 * If there is no from_header struct, then it's likely this message
163 * is locally generated and relying on fixups to add it. Just skip
164 * the entire DMARC system if we can't find a From: header....or if
165 * there was a previous error.
167 if (from_header == NULL || dmarc_abort == TRUE)
171 /* I strongly encourage anybody who can make this better to contact me directly!
172 * <cannonball> Is this an insane way to extract the email address from the From: header?
173 * <jgh_hm> it's sure a horrid layer-crossing....
174 * <cannonball> I'm not denying that :-/
175 * <jgh_hm> there may well be no better though
177 header_from_sender = expand_string(
178 string_sprintf("${domain:${extract{1}{:}{${addresses:%s}}}}",
179 from_header->text) );
180 /* The opendmarc library extracts the domain from the email address, but
181 * only try to store it if it's not empty. Otherwise, skip out of DMARC. */
182 if (strcmp( CCS header_from_sender, "") == 0)
184 libdm_status = (dmarc_abort == TRUE) ?
186 opendmarc_policy_store_from_domain(dmarc_pctx, header_from_sender);
187 if (libdm_status != DMARC_PARSE_OKAY)
189 log_write(0, LOG_MAIN|LOG_PANIC, "failure to store header From: in DMARC: %s, header was '%s'",
190 opendmarc_policy_status_to_str(libdm_status), from_header->text);
195 /* Skip DMARC if connection is SMTP Auth. Temporarily, admin should
196 * instead do this in the ACLs. */
197 if (dmarc_abort == FALSE && sender_host_authenticated == NULL)
199 /* Use the envelope sender domain for this part of DMARC */
200 spf_sender_domain = expand_string(US"$sender_address_domain");
201 if ( spf_response == NULL )
203 /* No spf data means null envelope sender so generate a domain name
204 * from the sender_helo_name */
205 if (spf_sender_domain == NULL)
207 spf_sender_domain = sender_helo_name;
208 log_write(0, LOG_MAIN, "DMARC using synthesized SPF sender domain = %s\n",
211 debug_printf("DMARC using synthesized SPF sender domain = %s\n", spf_sender_domain);
213 dmarc_spf_result = DMARC_POLICY_SPF_OUTCOME_NONE;
214 dmarc_spf_ares_result = ARES_RESULT_UNKNOWN;
215 origin = DMARC_POLICY_SPF_ORIGIN_HELO;
216 spf_human_readable = US"";
220 sr = spf_response->result;
221 dmarc_spf_result = (sr == SPF_RESULT_NEUTRAL) ? DMARC_POLICY_SPF_OUTCOME_NONE :
222 (sr == SPF_RESULT_PASS) ? DMARC_POLICY_SPF_OUTCOME_PASS :
223 (sr == SPF_RESULT_FAIL) ? DMARC_POLICY_SPF_OUTCOME_FAIL :
224 (sr == SPF_RESULT_SOFTFAIL) ? DMARC_POLICY_SPF_OUTCOME_TMPFAIL :
225 DMARC_POLICY_SPF_OUTCOME_NONE;
226 dmarc_spf_ares_result = (sr == SPF_RESULT_NEUTRAL) ? ARES_RESULT_NEUTRAL :
227 (sr == SPF_RESULT_PASS) ? ARES_RESULT_PASS :
228 (sr == SPF_RESULT_FAIL) ? ARES_RESULT_FAIL :
229 (sr == SPF_RESULT_SOFTFAIL) ? ARES_RESULT_SOFTFAIL :
230 (sr == SPF_RESULT_NONE) ? ARES_RESULT_NONE :
231 (sr == SPF_RESULT_TEMPERROR) ? ARES_RESULT_TEMPERROR :
232 (sr == SPF_RESULT_PERMERROR) ? ARES_RESULT_PERMERROR :
234 origin = DMARC_POLICY_SPF_ORIGIN_MAILFROM;
235 spf_human_readable = (uschar *)spf_response->header_comment;
237 debug_printf("DMARC using SPF sender domain = %s\n", spf_sender_domain);
239 if (strcmp( CCS spf_sender_domain, "") == 0)
241 if (dmarc_abort == FALSE)
243 libdm_status = opendmarc_policy_store_spf(dmarc_pctx, spf_sender_domain,
244 dmarc_spf_result, origin, spf_human_readable);
245 if (libdm_status != DMARC_PARSE_OKAY)
246 log_write(0, LOG_MAIN|LOG_PANIC, "failure to store spf for DMARC: %s",
247 opendmarc_policy_status_to_str(libdm_status));
250 /* Now we cycle through the dkim signature results and put into
251 * the opendmarc context, further building the DMARC reply. */
252 sig = dkim_signatures;
253 dkim_history_buffer = US"";
256 int dkim_result, dkim_ares_result, vs, ves;
257 vs = sig->verify_status;
258 ves = sig->verify_ext_status;
259 dkim_result = ( vs == PDKIM_VERIFY_PASS ) ? DMARC_POLICY_DKIM_OUTCOME_PASS :
260 ( vs == PDKIM_VERIFY_FAIL ) ? DMARC_POLICY_DKIM_OUTCOME_FAIL :
261 ( vs == PDKIM_VERIFY_INVALID ) ? DMARC_POLICY_DKIM_OUTCOME_TMPFAIL :
262 DMARC_POLICY_DKIM_OUTCOME_NONE;
263 libdm_status = opendmarc_policy_store_dkim(dmarc_pctx, (uschar *)sig->domain,
266 debug_printf("DMARC adding DKIM sender domain = %s\n", sig->domain);
267 if (libdm_status != DMARC_PARSE_OKAY)
268 log_write(0, LOG_MAIN|LOG_PANIC, "failure to store dkim (%s) for DMARC: %s",
269 sig->domain, opendmarc_policy_status_to_str(libdm_status));
271 dkim_ares_result = ( vs == PDKIM_VERIFY_PASS ) ? ARES_RESULT_PASS :
272 ( vs == PDKIM_VERIFY_FAIL ) ? ARES_RESULT_FAIL :
273 ( vs == PDKIM_VERIFY_NONE ) ? ARES_RESULT_NONE :
274 ( vs == PDKIM_VERIFY_INVALID ) ?
275 ( ves == PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE ? ARES_RESULT_PERMERROR :
276 ves == PDKIM_VERIFY_INVALID_BUFFER_SIZE ? ARES_RESULT_PERMERROR :
277 ves == PDKIM_VERIFY_INVALID_PUBKEY_PARSING ? ARES_RESULT_PERMERROR :
278 ARES_RESULT_UNKNOWN ) :
280 dkim_history_buffer = string_sprintf("%sdkim %s %d\n", dkim_history_buffer,
281 sig->domain, dkim_ares_result);
284 libdm_status = opendmarc_policy_query_dmarc(dmarc_pctx, US"");
285 switch (libdm_status)
287 case DMARC_DNS_ERROR_NXDOMAIN:
288 case DMARC_DNS_ERROR_NO_RECORD:
290 debug_printf("DMARC no record found for %s\n", header_from_sender);
291 has_dmarc_record = FALSE;
293 case DMARC_PARSE_OKAY:
295 debug_printf("DMARC record found for %s\n", header_from_sender);
297 case DMARC_PARSE_ERROR_BAD_VALUE:
299 debug_printf("DMARC record parse error for %s\n", header_from_sender);
300 has_dmarc_record = FALSE;
303 /* everything else, skip dmarc */
305 debug_printf("DMARC skipping (%d), unsure what to do with %s",
306 libdm_status, from_header->text);
307 has_dmarc_record = FALSE;
310 /* Can't use exim's string manipulation functions so allocate memory
311 * for libopendmarc using its max hostname length definition. */
312 uschar *dmarc_domain = (uschar *)calloc(DMARC_MAXHOSTNAMELEN, sizeof(uschar));
313 libdm_status = opendmarc_policy_fetch_utilized_domain(dmarc_pctx, dmarc_domain,
314 DMARC_MAXHOSTNAMELEN-1);
315 dmarc_used_domain = string_copy(dmarc_domain);
317 if (libdm_status != DMARC_PARSE_OKAY)
319 log_write(0, LOG_MAIN|LOG_PANIC, "failure to read domainname used for DMARC lookup: %s",
320 opendmarc_policy_status_to_str(libdm_status));
322 libdm_status = opendmarc_get_policy_to_enforce(dmarc_pctx);
323 dmarc_policy = libdm_status;
326 case DMARC_POLICY_ABSENT: /* No DMARC record found */
327 dmarc_status = US"norecord";
328 dmarc_pass_fail = US"temperror";
329 dmarc_status_text = US"No DMARC record";
330 action = DMARC_RESULT_ACCEPT;
332 case DMARC_FROM_DOMAIN_ABSENT: /* No From: domain */
333 dmarc_status = US"nofrom";
334 dmarc_pass_fail = US"temperror";
335 dmarc_status_text = US"No From: domain found";
336 action = DMARC_RESULT_ACCEPT;
338 case DMARC_POLICY_NONE: /* Accept and report */
339 dmarc_status = US"none";
340 dmarc_pass_fail = US"none";
341 dmarc_status_text = US"None, Accept";
342 action = DMARC_RESULT_ACCEPT;
344 case DMARC_POLICY_PASS: /* Explicit accept */
345 dmarc_status = US"accept";
346 dmarc_pass_fail = US"pass";
347 dmarc_status_text = US"Accept";
348 action = DMARC_RESULT_ACCEPT;
350 case DMARC_POLICY_REJECT: /* Explicit reject */
351 dmarc_status = US"reject";
352 dmarc_pass_fail = US"fail";
353 dmarc_status_text = US"Reject";
354 action = DMARC_RESULT_REJECT;
356 case DMARC_POLICY_QUARANTINE: /* Explicit quarantine */
357 dmarc_status = US"quarantine";
358 dmarc_pass_fail = US"fail";
359 dmarc_status_text = US"Quarantine";
360 action = DMARC_RESULT_QUARANTINE;
363 dmarc_status = US"temperror";
364 dmarc_pass_fail = US"temperror";
365 dmarc_status_text = US"Internal Policy Error";
366 action = DMARC_RESULT_TEMPFAIL;
370 libdm_status = opendmarc_policy_fetch_alignment(dmarc_pctx, &da, &sa);
371 if (libdm_status != DMARC_PARSE_OKAY)
373 log_write(0, LOG_MAIN|LOG_PANIC, "failure to read DMARC alignment: %s",
374 opendmarc_policy_status_to_str(libdm_status));
377 if (has_dmarc_record == TRUE)
379 log_write(0, LOG_MAIN, "DMARC results: spf_domain=%s dmarc_domain=%s "
380 "spf_align=%s dkim_align=%s enforcement='%s'",
381 spf_sender_domain, dmarc_used_domain,
382 (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?"yes":"no",
383 (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?"yes":"no",
385 history_file_status = dmarc_write_history_file();
386 /* Now get the forensic reporting addresses, if any */
387 ruf = opendmarc_policy_fetch_ruf(dmarc_pctx, NULL, 0, 1);
388 dmarc_send_forensic_report(ruf);
392 /* set some global variables here */
393 dmarc_ar_header = dmarc_auth_results_header(from_header, NULL);
395 /* shut down libopendmarc */
396 if ( dmarc_pctx != NULL )
397 (void) opendmarc_policy_connect_shutdown(dmarc_pctx);
398 if ( dmarc_disable_verify == FALSE )
399 (void) opendmarc_policy_library_shutdown(&dmarc_ctx);
404 int dmarc_write_history_file()
409 u_char **rua; /* aggregate report addressees */
410 uschar *history_buffer = NULL;
412 if (dmarc_history_file == NULL)
413 return DMARC_HIST_DISABLED;
414 history_file_fd = log_create(dmarc_history_file);
416 if (history_file_fd < 0)
418 log_write(0, LOG_MAIN|LOG_PANIC, "failure to create DMARC history file: %s",
420 return DMARC_HIST_FILE_ERR;
423 /* Generate the contents of the history file */
424 history_buffer = string_sprintf("job %s\n", message_id);
425 history_buffer = string_sprintf("%sreporter %s\n", history_buffer, primary_hostname);
426 history_buffer = string_sprintf("%sreceived %ld\n", history_buffer, time(NULL));
427 history_buffer = string_sprintf("%sipaddr %s\n", history_buffer, sender_host_address);
428 history_buffer = string_sprintf("%sfrom %s\n", history_buffer, header_from_sender);
429 history_buffer = string_sprintf("%smfrom %s\n", history_buffer,
430 expand_string(US"$sender_address_domain"));
432 if (spf_response != NULL)
433 history_buffer = string_sprintf("%sspf %d\n", history_buffer, dmarc_spf_ares_result);
434 // history_buffer = string_sprintf("%sspf -1\n", history_buffer);
436 history_buffer = string_sprintf("%s%s", history_buffer, dkim_history_buffer);
437 history_buffer = string_sprintf("%spdomain %s\n", history_buffer, dmarc_used_domain);
438 history_buffer = string_sprintf("%spolicy %d\n", history_buffer, dmarc_policy);
440 rua = opendmarc_policy_fetch_rua(dmarc_pctx, NULL, 0, 1);
443 for (tmp_ans = 0; rua[tmp_ans] != NULL; tmp_ans++)
445 history_buffer = string_sprintf("%srua %s\n", history_buffer, rua[tmp_ans]);
449 history_buffer = string_sprintf("%srua -\n", history_buffer);
451 opendmarc_policy_fetch_pct(dmarc_pctx, &tmp_ans);
452 history_buffer = string_sprintf("%spct %d\n", history_buffer, tmp_ans);
454 opendmarc_policy_fetch_adkim(dmarc_pctx, &tmp_ans);
455 history_buffer = string_sprintf("%sadkim %d\n", history_buffer, tmp_ans);
457 opendmarc_policy_fetch_aspf(dmarc_pctx, &tmp_ans);
458 history_buffer = string_sprintf("%saspf %d\n", history_buffer, tmp_ans);
460 opendmarc_policy_fetch_p(dmarc_pctx, &tmp_ans);
461 history_buffer = string_sprintf("%sp %d\n", history_buffer, tmp_ans);
463 opendmarc_policy_fetch_sp(dmarc_pctx, &tmp_ans);
464 history_buffer = string_sprintf("%ssp %d\n", history_buffer, tmp_ans);
466 history_buffer = string_sprintf("%salign_dkim %d\n", history_buffer, da);
467 history_buffer = string_sprintf("%salign_spf %d\n", history_buffer, sa);
468 history_buffer = string_sprintf("%saction %d\n", history_buffer, action);
470 /* Write the contents to the history file */
472 debug_printf("DMARC logging history data for opendmarc reporting%s\n",
473 (host_checking || running_in_test_harness) ? " (not really)" : "");
474 if (host_checking || running_in_test_harness)
477 debug_printf("DMARC history data for debugging:\n%s", history_buffer);
481 written_len = write_to_fd_buf(history_file_fd,
483 Ustrlen(history_buffer));
484 if (written_len == 0)
486 log_write(0, LOG_MAIN|LOG_PANIC, "failure to write to DMARC history file: %s",
488 return DMARC_HIST_WRITE_ERR;
490 (void)close(history_file_fd);
492 return DMARC_HIST_OK;
495 void dmarc_send_forensic_report(u_char **ruf)
498 uschar *recipient, *save_sender;
499 BOOL send_status = FALSE;
500 error_block *eblock = NULL;
501 FILE *message_file = NULL;
503 /* Earlier ACL does not have *required* control=dmarc_enable_forensic */
504 if (dmarc_enable_forensic == FALSE)
507 if ((dmarc_policy == DMARC_POLICY_REJECT && action == DMARC_RESULT_REJECT) ||
508 (dmarc_policy == DMARC_POLICY_QUARANTINE && action == DMARC_RESULT_QUARANTINE) )
512 eblock = add_to_eblock(eblock, US"Sender Domain", dmarc_used_domain);
513 eblock = add_to_eblock(eblock, US"Sender IP Address", sender_host_address);
514 eblock = add_to_eblock(eblock, US"Received Date", tod_stamp(tod_full));
515 eblock = add_to_eblock(eblock, US"SPF Alignment",
516 (sa==DMARC_POLICY_SPF_ALIGNMENT_PASS) ?US"yes":US"no");
517 eblock = add_to_eblock(eblock, US"DKIM Alignment",
518 (da==DMARC_POLICY_DKIM_ALIGNMENT_PASS)?US"yes":US"no");
519 eblock = add_to_eblock(eblock, US"DMARC Results", dmarc_status_text);
520 /* Set a sane default envelope sender */
521 dsn_from = dmarc_forensic_sender ? dmarc_forensic_sender :
522 dsn_from ? dsn_from :
523 string_sprintf("do-not-reply@%s",primary_hostname);
524 for (c = 0; ruf[c] != NULL; c++)
526 recipient = string_copylc(ruf[c]);
527 if (Ustrncmp(recipient, "mailto:",7))
529 /* Move to first character past the colon */
532 debug_printf("DMARC forensic report to %s%s\n", recipient,
533 (host_checking || running_in_test_harness) ? " (not really)" : "");
534 if (host_checking || running_in_test_harness)
536 save_sender = sender_address;
537 sender_address = recipient;
538 send_status = moan_to_sender(ERRMESS_DMARC_FORENSIC, eblock,
539 header_list, message_file, FALSE);
540 sender_address = save_sender;
541 if (send_status == FALSE)
542 log_write(0, LOG_MAIN|LOG_PANIC, "failure to send DMARC forensic report to %s",
549 uschar *dmarc_exim_expand_query(int what)
551 if (dmarc_disable_verify || !dmarc_pctx)
552 return dmarc_exim_expand_defaults(what);
555 case DMARC_VERIFY_STATUS:
556 return(dmarc_status);
562 uschar *dmarc_exim_expand_defaults(int what)
565 case DMARC_VERIFY_STATUS:
566 return (dmarc_disable_verify) ?
574 uschar *dmarc_auth_results_header(header_line *from_header, uschar *hostname)
576 uschar *hdr_tmp = US"";
578 /* Allow a server hostname to be passed to this function, but is
579 * currently unused */
580 if (hostname == NULL)
581 hostname = primary_hostname;
582 hdr_tmp = string_sprintf("%s %s;", DMARC_AR_HEADER, hostname);
585 /* I don't think this belongs here, but left it here commented out
586 * because it was a lot of work to get working right. */
587 if (spf_response != NULL) {
588 uschar *dmarc_ar_spf = US"";
590 sr = spf_response->result;
591 dmarc_ar_spf = (sr == SPF_RESULT_NEUTRAL) ? US"neutral" :
592 (sr == SPF_RESULT_PASS) ? US"pass" :
593 (sr == SPF_RESULT_FAIL) ? US"fail" :
594 (sr == SPF_RESULT_SOFTFAIL) ? US"softfail" :
596 hdr_tmp = string_sprintf("%s spf=%s (%s) smtp.mail=%s;",
597 hdr_tmp, dmarc_ar_spf_result,
598 spf_response->header_comment,
599 expand_string(US"$sender_address") );
602 hdr_tmp = string_sprintf("%s dmarc=%s",
603 hdr_tmp, dmarc_pass_fail);
604 if (header_from_sender)
605 hdr_tmp = string_sprintf("%s header.from=%s",
606 hdr_tmp, header_from_sender);
610 #endif /* EXPERIMENTAL_SPF */
611 #endif /* EXPERIMENTAL_DMARC */
613 // vim:sw=2 expandtab