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 header_line
*from_header
= NULL
;
32 extern SPF_response_t
*spf_response
;
33 int dmarc_spf_ares_result
= 0;
34 uschar
*spf_sender_domain
= NULL
;
35 uschar
*spf_human_readable
= NULL
;
36 u_char
*header_from_sender
= NULL
;
37 int history_file_status
= DMARC_HIST_OK
;
38 uschar
*dkim_history_buffer
= NULL
;
40 typedef struct dmarc_exim_p
{
45 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) */
84 int *netmask
= NULL
; /* Ignored */
87 /* Set some sane defaults. Also clears previous results when
88 * multiple messages in one connection. */
90 dmarc_status
= US
"none";
92 dmarc_pass_fail
= US
"skipped";
93 dmarc_used_domain
= US
"";
94 f
.dmarc_has_been_checked
= FALSE
;
95 header_from_sender
= NULL
;
96 spf_sender_domain
= NULL
;
97 spf_human_readable
= NULL
;
99 /* ACLs have "control=dmarc_disable_verify" */
100 if (f
.dmarc_disable_verify
== TRUE
)
103 (void) memset(&dmarc_ctx
, '\0', sizeof dmarc_ctx
);
104 dmarc_ctx
.nscount
= 0;
105 libdm_status
= opendmarc_policy_library_init(&dmarc_ctx
);
106 if (libdm_status
!= DMARC_PARSE_OKAY
)
108 log_write(0, LOG_MAIN
|LOG_PANIC
, "DMARC failure to init library: %s",
109 opendmarc_policy_status_to_str(libdm_status
));
114 DEBUG(D_receive
) debug_printf("DMARC: no dmarc_tld_file\n");
117 else if (opendmarc_tld_read_file(CS dmarc_tld_file
, NULL
, NULL
, NULL
))
119 log_write(0, LOG_MAIN
|LOG_PANIC
, "DMARC failure to load tld list %s: %d",
120 dmarc_tld_file
, errno
);
123 if (!sender_host_address
)
125 DEBUG(D_receive
) debug_printf("DMARC: no sender_host_address\n");
128 /* This catches locally originated email and startup errors above. */
131 is_ipv6
= string_is_ip_address(sender_host_address
, netmask
) == 6;
132 if (!(dmarc_pctx
= opendmarc_policy_connect_init(sender_host_address
, is_ipv6
)))
134 log_write(0, LOG_MAIN
|LOG_PANIC
,
135 "DMARC failure creating policy context: ip=%s", sender_host_address
);
144 /* dmarc_store_data stores the header data so that subsequent
145 dmarc_process can access the data */
148 dmarc_store_data(header_line
*hdr
)
150 /* No debug output because would change every test debug output */
151 if (!f
.dmarc_disable_verify
)
158 dmarc_send_forensic_report(u_char
**ruf
)
160 uschar
*recipient
, *save_sender
;
161 BOOL send_status
= FALSE
;
162 error_block
*eblock
= NULL
;
163 FILE *message_file
= NULL
;
165 /* Earlier ACL does not have *required* control=dmarc_enable_forensic */
166 if (!f
.dmarc_enable_forensic
)
169 if ( dmarc_policy
== DMARC_POLICY_REJECT
&& action
== DMARC_RESULT_REJECT
170 || dmarc_policy
== DMARC_POLICY_QUARANTINE
&& action
== DMARC_RESULT_QUARANTINE
171 || dmarc_policy
== DMARC_POLICY_NONE
&& action
== DMARC_RESULT_REJECT
172 || dmarc_policy
== DMARC_POLICY_NONE
&& action
== DMARC_RESULT_QUARANTINE
176 eblock
= add_to_eblock(eblock
, US
"Sender Domain", dmarc_used_domain
);
177 eblock
= add_to_eblock(eblock
, US
"Sender IP Address", sender_host_address
);
178 eblock
= add_to_eblock(eblock
, US
"Received Date", tod_stamp(tod_full
));
179 eblock
= add_to_eblock(eblock
, US
"SPF Alignment",
180 sa
== DMARC_POLICY_SPF_ALIGNMENT_PASS
? US
"yes" : US
"no");
181 eblock
= add_to_eblock(eblock
, US
"DKIM Alignment",
182 da
== DMARC_POLICY_DKIM_ALIGNMENT_PASS
? US
"yes" : US
"no");
183 eblock
= add_to_eblock(eblock
, US
"DMARC Results", dmarc_status_text
);
185 for (int c
= 0; ruf
[c
]; c
++)
187 recipient
= string_copylc(ruf
[c
]);
188 if (Ustrncmp(recipient
, "mailto:",7))
190 /* Move to first character past the colon */
193 debug_printf("DMARC forensic report to %s%s\n", recipient
,
194 (host_checking
|| f
.running_in_test_harness
) ? " (not really)" : "");
195 if (host_checking
|| f
.running_in_test_harness
)
198 if (!moan_send_message(recipient
, ERRMESS_DMARC_FORENSIC
, eblock
,
199 header_list
, message_file
, NULL
))
200 log_write(0, LOG_MAIN
|LOG_PANIC
,
201 "failure to send DMARC forensic report to %s", recipient
);
206 /* dmarc_process adds the envelope sender address to the existing
207 context (if any), retrieves the result, sets up expansion
208 strings and evaluates the condition outcome. */
213 int sr
, origin
; /* used in SPF section */
214 int dmarc_spf_result
= 0; /* stores spf into dmarc conn ctx */
216 pdkim_signature
* sig
= dkim_signatures
;
217 BOOL has_dmarc_record
= TRUE
;
218 u_char
**ruf
; /* forensic report addressees, if called for */
220 /* ACLs have "control=dmarc_disable_verify" */
221 if (f
.dmarc_disable_verify
)
224 /* Store the header From: sender domain for this part of DMARC.
225 * If there is no from_header struct, then it's likely this message
226 * is locally generated and relying on fixups to add it. Just skip
227 * the entire DMARC system if we can't find a From: header....or if
228 * there was a previous error.
232 DEBUG(D_receive
) debug_printf("DMARC: no From: header\n");
235 else if (!dmarc_abort
)
242 f
.parse_allow_group
= TRUE
;
243 p
= parse_find_address_end(from_header
->text
, FALSE
);
244 saveend
= *p
; *p
= '\0';
245 if ((header_from_sender
= parse_extract_address(from_header
->text
, &errormsg
,
246 &dummy
, &dummy
, &domain
, FALSE
)))
247 header_from_sender
+= domain
;
250 /* The opendmarc library extracts the domain from the email address, but
251 * only try to store it if it's not empty. Otherwise, skip out of DMARC. */
252 if (!header_from_sender
|| (strcmp( CCS header_from_sender
, "") == 0))
254 libdm_status
= dmarc_abort
256 : opendmarc_policy_store_from_domain(dmarc_pctx
, header_from_sender
);
257 if (libdm_status
!= DMARC_PARSE_OKAY
)
259 log_write(0, LOG_MAIN
|LOG_PANIC
,
260 "failure to store header From: in DMARC: %s, header was '%s'",
261 opendmarc_policy_status_to_str(libdm_status
), from_header
->text
);
266 /* Skip DMARC if connection is SMTP Auth. Temporarily, admin should
267 * instead do this in the ACLs. */
268 if (!dmarc_abort
&& !sender_host_authenticated
)
270 uschar
* dmarc_domain
;
272 /* Use the envelope sender domain for this part of DMARC */
273 spf_sender_domain
= expand_string(US
"$sender_address_domain");
276 /* No spf data means null envelope sender so generate a domain name
277 * from the sender_helo_name */
278 if (!spf_sender_domain
)
280 spf_sender_domain
= sender_helo_name
;
281 log_write(0, LOG_MAIN
, "DMARC using synthesized SPF sender domain = %s\n",
284 debug_printf("DMARC using synthesized SPF sender domain = %s\n",
287 dmarc_spf_result
= DMARC_POLICY_SPF_OUTCOME_NONE
;
288 dmarc_spf_ares_result
= ARES_RESULT_UNKNOWN
;
289 origin
= DMARC_POLICY_SPF_ORIGIN_HELO
;
290 spf_human_readable
= US
"";
294 sr
= spf_response
->result
;
295 dmarc_spf_result
= sr
== SPF_RESULT_NEUTRAL
? DMARC_POLICY_SPF_OUTCOME_NONE
:
296 sr
== SPF_RESULT_PASS
? DMARC_POLICY_SPF_OUTCOME_PASS
:
297 sr
== SPF_RESULT_FAIL
? DMARC_POLICY_SPF_OUTCOME_FAIL
:
298 sr
== SPF_RESULT_SOFTFAIL
? DMARC_POLICY_SPF_OUTCOME_TMPFAIL
:
299 DMARC_POLICY_SPF_OUTCOME_NONE
;
300 dmarc_spf_ares_result
= sr
== SPF_RESULT_NEUTRAL
? ARES_RESULT_NEUTRAL
:
301 sr
== SPF_RESULT_PASS
? ARES_RESULT_PASS
:
302 sr
== SPF_RESULT_FAIL
? ARES_RESULT_FAIL
:
303 sr
== SPF_RESULT_SOFTFAIL
? ARES_RESULT_SOFTFAIL
:
304 sr
== SPF_RESULT_NONE
? ARES_RESULT_NONE
:
305 sr
== SPF_RESULT_TEMPERROR
? ARES_RESULT_TEMPERROR
:
306 sr
== SPF_RESULT_PERMERROR
? ARES_RESULT_PERMERROR
:
308 origin
= DMARC_POLICY_SPF_ORIGIN_MAILFROM
;
309 spf_human_readable
= US spf_response
->header_comment
;
311 debug_printf("DMARC using SPF sender domain = %s\n", spf_sender_domain
);
313 if (strcmp( CCS spf_sender_domain
, "") == 0)
317 libdm_status
= opendmarc_policy_store_spf(dmarc_pctx
, spf_sender_domain
,
318 dmarc_spf_result
, origin
, spf_human_readable
);
319 if (libdm_status
!= DMARC_PARSE_OKAY
)
320 log_write(0, LOG_MAIN
|LOG_PANIC
, "failure to store spf for DMARC: %s",
321 opendmarc_policy_status_to_str(libdm_status
));
324 /* Now we cycle through the dkim signature results and put into
325 * the opendmarc context, further building the DMARC reply. */
326 dkim_history_buffer
= US
"";
329 int dkim_result
, dkim_ares_result
, vs
, ves
;
331 vs
= sig
->verify_status
& ~PDKIM_VERIFY_POLICY
;
332 ves
= sig
->verify_ext_status
;
333 dkim_result
= vs
== PDKIM_VERIFY_PASS
? DMARC_POLICY_DKIM_OUTCOME_PASS
:
334 vs
== PDKIM_VERIFY_FAIL
? DMARC_POLICY_DKIM_OUTCOME_FAIL
:
335 vs
== PDKIM_VERIFY_INVALID
? DMARC_POLICY_DKIM_OUTCOME_TMPFAIL
:
336 DMARC_POLICY_DKIM_OUTCOME_NONE
;
337 libdm_status
= opendmarc_policy_store_dkim(dmarc_pctx
, US sig
->domain
,
340 debug_printf("DMARC adding DKIM sender domain = %s\n", sig
->domain
);
341 if (libdm_status
!= DMARC_PARSE_OKAY
)
342 log_write(0, LOG_MAIN
|LOG_PANIC
,
343 "failure to store dkim (%s) for DMARC: %s",
344 sig
->domain
, opendmarc_policy_status_to_str(libdm_status
));
347 vs
== PDKIM_VERIFY_PASS
? ARES_RESULT_PASS
:
348 vs
== PDKIM_VERIFY_FAIL
? ARES_RESULT_FAIL
:
349 vs
== PDKIM_VERIFY_NONE
? ARES_RESULT_NONE
:
350 vs
== PDKIM_VERIFY_INVALID
?
351 ves
== PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE
? ARES_RESULT_PERMERROR
:
352 ves
== PDKIM_VERIFY_INVALID_BUFFER_SIZE
? ARES_RESULT_PERMERROR
:
353 ves
== PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD
? ARES_RESULT_PERMERROR
:
354 ves
== PDKIM_VERIFY_INVALID_PUBKEY_IMPORT
? ARES_RESULT_PERMERROR
:
355 ARES_RESULT_UNKNOWN
:
357 dkim_history_buffer
= string_sprintf("%sdkim %s %d\n", dkim_history_buffer
,
358 sig
->domain
, dkim_ares_result
);
361 libdm_status
= opendmarc_policy_query_dmarc(dmarc_pctx
, US
"");
362 switch (libdm_status
)
364 case DMARC_DNS_ERROR_NXDOMAIN
:
365 case DMARC_DNS_ERROR_NO_RECORD
:
367 debug_printf("DMARC no record found for %s\n", header_from_sender
);
368 has_dmarc_record
= FALSE
;
370 case DMARC_PARSE_OKAY
:
372 debug_printf("DMARC record found for %s\n", header_from_sender
);
374 case DMARC_PARSE_ERROR_BAD_VALUE
:
376 debug_printf("DMARC record parse error for %s\n", header_from_sender
);
377 has_dmarc_record
= FALSE
;
380 /* everything else, skip dmarc */
382 debug_printf("DMARC skipping (%d), unsure what to do with %s",
383 libdm_status
, from_header
->text
);
384 has_dmarc_record
= FALSE
;
388 /* Store the policy string in an expandable variable. */
390 libdm_status
= opendmarc_policy_fetch_p(dmarc_pctx
, &tmp_ans
);
391 for (c
= 0; dmarc_policy_description
[c
].name
; c
++)
392 if (tmp_ans
== dmarc_policy_description
[c
].value
)
394 dmarc_domain_policy
= string_sprintf("%s",dmarc_policy_description
[c
].name
);
398 /* Can't use exim's string manipulation functions so allocate memory
399 for libopendmarc using its max hostname length definition. */
401 dmarc_domain
= US
calloc(DMARC_MAXHOSTNAMELEN
, sizeof(uschar
));
402 libdm_status
= opendmarc_policy_fetch_utilized_domain(dmarc_pctx
,
403 dmarc_domain
, DMARC_MAXHOSTNAMELEN
-1);
404 dmarc_used_domain
= string_copy(dmarc_domain
);
407 if (libdm_status
!= DMARC_PARSE_OKAY
)
408 log_write(0, LOG_MAIN
|LOG_PANIC
,
409 "failure to read domainname used for DMARC lookup: %s",
410 opendmarc_policy_status_to_str(libdm_status
));
412 dmarc_policy
= libdm_status
= opendmarc_get_policy_to_enforce(dmarc_pctx
);
415 case DMARC_POLICY_ABSENT
: /* No DMARC record found */
416 dmarc_status
= US
"norecord";
417 dmarc_pass_fail
= US
"none";
418 dmarc_status_text
= US
"No DMARC record";
419 action
= DMARC_RESULT_ACCEPT
;
421 case DMARC_FROM_DOMAIN_ABSENT
: /* No From: domain */
422 dmarc_status
= US
"nofrom";
423 dmarc_pass_fail
= US
"temperror";
424 dmarc_status_text
= US
"No From: domain found";
425 action
= DMARC_RESULT_ACCEPT
;
427 case DMARC_POLICY_NONE
: /* Accept and report */
428 dmarc_status
= US
"none";
429 dmarc_pass_fail
= US
"none";
430 dmarc_status_text
= US
"None, Accept";
431 action
= DMARC_RESULT_ACCEPT
;
433 case DMARC_POLICY_PASS
: /* Explicit accept */
434 dmarc_status
= US
"accept";
435 dmarc_pass_fail
= US
"pass";
436 dmarc_status_text
= US
"Accept";
437 action
= DMARC_RESULT_ACCEPT
;
439 case DMARC_POLICY_REJECT
: /* Explicit reject */
440 dmarc_status
= US
"reject";
441 dmarc_pass_fail
= US
"fail";
442 dmarc_status_text
= US
"Reject";
443 action
= DMARC_RESULT_REJECT
;
445 case DMARC_POLICY_QUARANTINE
: /* Explicit quarantine */
446 dmarc_status
= US
"quarantine";
447 dmarc_pass_fail
= US
"fail";
448 dmarc_status_text
= US
"Quarantine";
449 action
= DMARC_RESULT_QUARANTINE
;
452 dmarc_status
= US
"temperror";
453 dmarc_pass_fail
= US
"temperror";
454 dmarc_status_text
= US
"Internal Policy Error";
455 action
= DMARC_RESULT_TEMPFAIL
;
459 libdm_status
= opendmarc_policy_fetch_alignment(dmarc_pctx
, &da
, &sa
);
460 if (libdm_status
!= DMARC_PARSE_OKAY
)
461 log_write(0, LOG_MAIN
|LOG_PANIC
, "failure to read DMARC alignment: %s",
462 opendmarc_policy_status_to_str(libdm_status
));
464 if (has_dmarc_record
)
466 log_write(0, LOG_MAIN
, "DMARC results: spf_domain=%s dmarc_domain=%s "
467 "spf_align=%s dkim_align=%s enforcement='%s'",
468 spf_sender_domain
, dmarc_used_domain
,
469 sa
==DMARC_POLICY_SPF_ALIGNMENT_PASS
?"yes":"no",
470 da
==DMARC_POLICY_DKIM_ALIGNMENT_PASS
?"yes":"no",
472 history_file_status
= dmarc_write_history_file();
473 /* Now get the forensic reporting addresses, if any */
474 ruf
= opendmarc_policy_fetch_ruf(dmarc_pctx
, NULL
, 0, 1);
475 dmarc_send_forensic_report(ruf
);
479 /* shut down libopendmarc */
481 (void) opendmarc_policy_connect_shutdown(dmarc_pctx
);
482 if (!f
.dmarc_disable_verify
)
483 (void) opendmarc_policy_library_shutdown(&dmarc_ctx
);
489 dmarc_write_history_file()
494 u_char
**rua
; /* aggregate report addressees */
495 uschar
*history_buffer
= NULL
;
497 if (!dmarc_history_file
)
499 DEBUG(D_receive
) debug_printf("DMARC history file not set\n");
500 return DMARC_HIST_DISABLED
;
502 history_file_fd
= log_create(dmarc_history_file
);
504 if (history_file_fd
< 0)
506 log_write(0, LOG_MAIN
|LOG_PANIC
, "failure to create DMARC history file: %s",
508 return DMARC_HIST_FILE_ERR
;
511 /* Generate the contents of the history file */
512 history_buffer
= string_sprintf(
513 "job %s\nreporter %s\nreceived %ld\nipaddr %s\nfrom %s\nmfrom %s\n",
514 message_id
, primary_hostname
, time(NULL
), sender_host_address
,
515 header_from_sender
, expand_string(US
"$sender_address_domain"));
518 history_buffer
= string_sprintf("%sspf %d\n", history_buffer
, dmarc_spf_ares_result
);
519 /* history_buffer = string_sprintf("%sspf -1\n", history_buffer); */
521 history_buffer
= string_sprintf(
522 "%s%spdomain %s\npolicy %d\n",
523 history_buffer
, dkim_history_buffer
, dmarc_used_domain
, dmarc_policy
);
525 if ((rua
= opendmarc_policy_fetch_rua(dmarc_pctx
, NULL
, 0, 1)))
526 for (tmp_ans
= 0; rua
[tmp_ans
]; tmp_ans
++)
527 history_buffer
= string_sprintf("%srua %s\n", history_buffer
, rua
[tmp_ans
]);
529 history_buffer
= string_sprintf("%srua -\n", history_buffer
);
531 opendmarc_policy_fetch_pct(dmarc_pctx
, &tmp_ans
);
532 history_buffer
= string_sprintf("%spct %d\n", history_buffer
, tmp_ans
);
534 opendmarc_policy_fetch_adkim(dmarc_pctx
, &tmp_ans
);
535 history_buffer
= string_sprintf("%sadkim %d\n", history_buffer
, tmp_ans
);
537 opendmarc_policy_fetch_aspf(dmarc_pctx
, &tmp_ans
);
538 history_buffer
= string_sprintf("%saspf %d\n", history_buffer
, tmp_ans
);
540 opendmarc_policy_fetch_p(dmarc_pctx
, &tmp_ans
);
541 history_buffer
= string_sprintf("%sp %d\n", history_buffer
, tmp_ans
);
543 opendmarc_policy_fetch_sp(dmarc_pctx
, &tmp_ans
);
544 history_buffer
= string_sprintf("%ssp %d\n", history_buffer
, tmp_ans
);
546 history_buffer
= string_sprintf(
547 "%salign_dkim %d\nalign_spf %d\naction %d\n",
548 history_buffer
, da
, sa
, action
);
550 /* Write the contents to the history file */
552 debug_printf("DMARC logging history data for opendmarc reporting%s\n",
553 (host_checking
|| f
.running_in_test_harness
) ? " (not really)" : "");
554 if (host_checking
|| f
.running_in_test_harness
)
557 debug_printf("DMARC history data for debugging:\n%s", history_buffer
);
561 written_len
= write_to_fd_buf(history_file_fd
,
563 Ustrlen(history_buffer
));
564 if (written_len
== 0)
566 log_write(0, LOG_MAIN
|LOG_PANIC
, "failure to write to DMARC history file: %s",
568 return DMARC_HIST_WRITE_ERR
;
570 (void)close(history_file_fd
);
572 return DMARC_HIST_OK
;
577 dmarc_exim_expand_query(int what
)
579 if (f
.dmarc_disable_verify
|| !dmarc_pctx
)
580 return dmarc_exim_expand_defaults(what
);
582 if (what
== DMARC_VERIFY_STATUS
)
588 dmarc_exim_expand_defaults(int what
)
590 if (what
== DMARC_VERIFY_STATUS
)
591 return f
.dmarc_disable_verify
? US
"off" : US
"none";
597 authres_dmarc(gstring
* g
)
599 if (f
.dmarc_has_been_checked
)
601 g
= string_append(g
, 2, US
";\n\tdmarc=", dmarc_pass_fail
);
602 if (header_from_sender
)
603 g
= string_append(g
, 2, US
" header.from=", header_from_sender
);
608 # endif /* SUPPORT_SPF */
609 #endif /* EXPERIMENTAL_DMARC */