Commit | Line | Data |
---|---|---|
617d3932 JH |
1 | /************************************************* |
2 | * Exim - an Internet mail transport agent * | |
3 | *************************************************/ | |
4 | /* Experimental ARC support for Exim | |
5 | Copyright (c) Jeremy Harris 2018 | |
6 | License: GPL | |
7 | */ | |
8 | ||
9 | #include "exim.h" | |
10 | #ifdef EXPERIMENTAL_ARC | |
11 | # if !defined SUPPORT_SPF | |
12 | # error SPF must also be enabled for ARC | |
13 | # elif defined DISABLE_DKIM | |
14 | # error DKIM must also be enabled for ARC | |
15 | # else | |
16 | ||
17 | # include "functions.h" | |
18 | # include "pdkim/pdkim.h" | |
19 | # include "pdkim/signing.h" | |
20 | ||
21 | extern pdkim_ctx * dkim_verify_ctx; | |
22 | extern pdkim_ctx dkim_sign_ctx; | |
23 | ||
a93dbf44 | 24 | #define ARC_SIGN_OPT_TSTAMP BIT(0) |
0e83c148 JH |
25 | #define ARC_SIGN_OPT_EXPIRE BIT(1) |
26 | ||
27 | #define ARC_SIGN_DEFAULT_EXPIRE_DELTA (60 * 60 * 24 * 30) /* one month */ | |
a93dbf44 | 28 | |
617d3932 JH |
29 | /******************************************************************************/ |
30 | ||
31 | typedef struct hdr_rlist { | |
32 | struct hdr_rlist * prev; | |
33 | BOOL used; | |
34 | header_line * h; | |
35 | } hdr_rlist; | |
36 | ||
37 | typedef struct arc_line { | |
38 | header_line * complete; /* including the header name; nul-term */ | |
39 | uschar * relaxed; | |
40 | ||
41 | /* identified tag contents */ | |
42 | /*XXX t= for AS? */ | |
43 | blob i; | |
44 | blob cv; | |
45 | blob a; | |
46 | blob b; | |
47 | blob bh; | |
48 | blob d; | |
49 | blob h; | |
50 | blob s; | |
51 | blob c; | |
52 | blob l; | |
53 | ||
54 | /* tag content sub-portions */ | |
55 | blob a_algo; | |
56 | blob a_hash; | |
57 | ||
58 | blob c_head; | |
59 | blob c_body; | |
60 | ||
61 | /* modified copy of b= field in line */ | |
62 | blob rawsig_no_b_val; | |
63 | } arc_line; | |
64 | ||
65 | typedef struct arc_set { | |
66 | struct arc_set * next; | |
67 | struct arc_set * prev; | |
68 | ||
69 | unsigned instance; | |
70 | arc_line * hdr_aar; | |
71 | arc_line * hdr_ams; | |
72 | arc_line * hdr_as; | |
73 | ||
93c931f8 | 74 | const uschar * ams_verify_done; |
617d3932 JH |
75 | BOOL ams_verify_passed; |
76 | } arc_set; | |
77 | ||
78 | typedef struct arc_ctx { | |
79 | arc_set * arcset_chain; | |
80 | arc_set * arcset_chain_last; | |
81 | } arc_ctx; | |
82 | ||
83 | #define ARC_HDR_AAR US"ARC-Authentication-Results:" | |
84 | #define ARC_HDRLEN_AAR 27 | |
85 | #define ARC_HDR_AMS US"ARC-Message-Signature:" | |
86 | #define ARC_HDRLEN_AMS 22 | |
87 | #define ARC_HDR_AS US"ARC-Seal:" | |
88 | #define ARC_HDRLEN_AS 9 | |
89 | #define HDR_AR US"Authentication-Results:" | |
90 | #define HDRLEN_AR 23 | |
91 | ||
0e83c148 JH |
92 | static time_t now; |
93 | static time_t expire; | |
617d3932 JH |
94 | static hdr_rlist * headers_rlist; |
95 | static arc_ctx arc_sign_ctx = { NULL }; | |
96 | ||
97 | ||
98 | /******************************************************************************/ | |
99 | ||
100 | ||
101 | /* Get the instance number from the header. | |
102 | Return 0 on error */ | |
103 | static unsigned | |
104 | arc_instance_from_hdr(const arc_line * al) | |
105 | { | |
978e78de | 106 | const uschar * s = al->i.data; |
617d3932 | 107 | if (!s || !al->i.len) return 0; |
978e78de | 108 | return (unsigned) atoi(CCS s); |
617d3932 JH |
109 | } |
110 | ||
111 | ||
112 | static uschar * | |
113 | skip_fws(uschar * s) | |
114 | { | |
115 | uschar c = *s; | |
116 | while (c && (c == ' ' || c == '\t' || c == '\n' || c == '\r')) c = *++s; | |
117 | return s; | |
118 | } | |
119 | ||
120 | ||
121 | /* Locate instance struct on chain, inserting a new one if | |
122 | needed. The chain is in increasing-instance-number order | |
123 | by the "next" link, and we have a "prev" link also. | |
124 | */ | |
125 | ||
126 | static arc_set * | |
127 | arc_find_set(arc_ctx * ctx, unsigned i) | |
128 | { | |
129 | arc_set ** pas, * as, * next, * prev; | |
130 | ||
131 | for (pas = &ctx->arcset_chain, prev = NULL, next = ctx->arcset_chain; | |
132 | as = *pas; pas = &as->next) | |
133 | { | |
134 | if (as->instance > i) break; | |
135 | if (as->instance == i) | |
136 | { | |
137 | DEBUG(D_acl) debug_printf("ARC: existing instance %u\n", i); | |
138 | return as; | |
139 | } | |
140 | next = as->next; | |
141 | prev = as; | |
142 | } | |
143 | ||
144 | DEBUG(D_acl) debug_printf("ARC: new instance %u\n", i); | |
145 | *pas = as = store_get(sizeof(arc_set)); | |
146 | memset(as, 0, sizeof(arc_set)); | |
147 | as->next = next; | |
148 | as->prev = prev; | |
149 | as->instance = i; | |
150 | if (next) | |
151 | next->prev = as; | |
152 | else | |
153 | ctx->arcset_chain_last = as; | |
154 | return as; | |
155 | } | |
156 | ||
157 | ||
158 | ||
159 | /* Insert a tag content into the line structure. | |
160 | Note this is a reference to existing data, not a copy. | |
161 | Check for already-seen tag. | |
162 | The string-pointer is on the '=' for entry. Update it past the | |
163 | content (to the ;) on return; | |
164 | */ | |
165 | ||
166 | static uschar * | |
167 | arc_insert_tagvalue(arc_line * al, unsigned loff, uschar ** ss) | |
168 | { | |
169 | uschar * s = *ss; | |
170 | uschar c = *++s; | |
171 | blob * b = (blob *)(US al + loff); | |
172 | size_t len = 0; | |
173 | ||
174 | /* [FWS] tag-value [FWS] */ | |
175 | ||
176 | if (b->data) return US"fail"; | |
177 | s = skip_fws(s); /* FWS */ | |
178 | ||
179 | b->data = s; | |
180 | while ((c = *s) && c != ';') { len++; s++; } | |
181 | *ss = s; | |
182 | while (len && ((c = s[-1]) == ' ' || c == '\t' || c == '\n' || c == '\r')) | |
183 | { s--; len--; } /* FWS */ | |
184 | b->len = len; | |
185 | return NULL; | |
186 | } | |
187 | ||
188 | ||
189 | /* Inspect a header line, noting known tag fields. | |
190 | Check for duplicates. */ | |
191 | ||
192 | static uschar * | |
193 | arc_parse_line(arc_line * al, header_line * h, unsigned off, BOOL instance_only) | |
194 | { | |
195 | uschar * s = h->text + off; | |
978e78de | 196 | uschar * r = NULL; /* compiler-quietening */ |
617d3932 JH |
197 | uschar c; |
198 | ||
199 | al->complete = h; | |
200 | ||
201 | if (!instance_only) | |
202 | { | |
203 | al->rawsig_no_b_val.data = store_get(h->slen + 1); | |
204 | memcpy(al->rawsig_no_b_val.data, h->text, off); /* copy the header name blind */ | |
205 | r = al->rawsig_no_b_val.data + off; | |
206 | al->rawsig_no_b_val.len = off; | |
207 | } | |
208 | ||
209 | /* tag-list = tag-spec *( ";" tag-spec ) [ ";" ] */ | |
210 | ||
211 | while ((c = *s)) | |
212 | { | |
213 | char tagchar; | |
214 | uschar * t; | |
215 | unsigned i = 0; | |
216 | uschar * fieldstart = s; | |
217 | uschar * bstart = NULL, * bend; | |
218 | ||
219 | /* tag-spec = [FWS] tag-name [FWS] "=" [FWS] tag-value [FWS] */ | |
220 | ||
221 | s = skip_fws(s); /* FWS */ | |
222 | if (!*s) break; | |
223 | /* debug_printf("%s: consider '%s'\n", __FUNCTION__, s); */ | |
224 | tagchar = *s++; | |
225 | s = skip_fws(s); /* FWS */ | |
226 | if (!*s) break; | |
227 | ||
228 | if (!instance_only || tagchar == 'i') switch (tagchar) | |
229 | { | |
230 | case 'a': /* a= AMS algorithm */ | |
231 | { | |
232 | if (*s != '=') return US"no 'a' value"; | |
233 | if (arc_insert_tagvalue(al, offsetof(arc_line, a), &s)) return US"a tag dup"; | |
234 | ||
235 | /* substructure: algo-hash (eg. rsa-sha256) */ | |
236 | ||
237 | t = al->a_algo.data = al->a.data; | |
238 | while (*t != '-') | |
239 | if (!*t++ || ++i > al->a.len) return US"no '-' in 'a' value"; | |
240 | al->a_algo.len = i; | |
241 | if (*t++ != '-') return US"no '-' in 'a' value"; | |
242 | al->a_hash.data = t; | |
243 | al->a_hash.len = al->a.len - i - 1; | |
244 | } | |
245 | break; | |
246 | case 'b': | |
247 | { | |
248 | gstring * g = NULL; | |
249 | ||
250 | switch (*s) | |
251 | { | |
252 | case '=': /* b= AMS signature */ | |
253 | if (al->b.data) return US"already b data"; | |
254 | bstart = s+1; | |
255 | ||
256 | /* The signature can have FWS inserted in the content; | |
257 | make a stripped copy */ | |
258 | ||
259 | while ((c = *++s) && c != ';') | |
260 | if (c != ' ' && c != '\t' && c != '\n' && c != '\r') | |
261 | g = string_catn(g, s, 1); | |
262 | al->b.data = string_from_gstring(g); | |
263 | al->b.len = g->ptr; | |
264 | gstring_reset_unused(g); | |
265 | bend = s; | |
266 | break; | |
267 | case 'h': /* bh= AMS body hash */ | |
268 | s = skip_fws(++s); /* FWS */ | |
269 | if (*s != '=') return US"no bh value"; | |
270 | if (al->bh.data) return US"already bh data"; | |
271 | ||
272 | /* The bodyhash can have FWS inserted in the content; | |
273 | make a stripped copy */ | |
274 | ||
275 | while ((c = *++s) && c != ';') | |
276 | if (c != ' ' && c != '\t' && c != '\n' && c != '\r') | |
277 | g = string_catn(g, s, 1); | |
278 | al->bh.data = string_from_gstring(g); | |
279 | al->bh.len = g->ptr; | |
280 | gstring_reset_unused(g); | |
281 | break; | |
282 | default: | |
283 | return US"b? tag"; | |
284 | } | |
285 | } | |
286 | break; | |
287 | case 'c': | |
288 | switch (*s) | |
289 | { | |
290 | case '=': /* c= AMS canonicalisation */ | |
291 | if (arc_insert_tagvalue(al, offsetof(arc_line, c), &s)) return US"c tag dup"; | |
292 | ||
293 | /* substructure: head/body (eg. relaxed/simple)) */ | |
294 | ||
295 | t = al->c_head.data = al->c.data; | |
296 | while (isalpha(*t)) | |
297 | if (!*t++ || ++i > al->a.len) break; | |
298 | al->c_head.len = i; | |
299 | if (*t++ == '/') /* /body is optional */ | |
300 | { | |
301 | al->c_body.data = t; | |
302 | al->c_body.len = al->c.len - i - 1; | |
303 | } | |
304 | else | |
305 | { | |
306 | al->c_body.data = US"simple"; | |
307 | al->c_body.len = 6; | |
308 | } | |
309 | break; | |
310 | case 'v': /* cv= AS validity */ | |
311 | if (*++s != '=') return US"cv tag val"; | |
312 | if (arc_insert_tagvalue(al, offsetof(arc_line, cv), &s)) return US"cv tag dup"; | |
313 | break; | |
314 | default: | |
315 | return US"c? tag"; | |
316 | } | |
317 | break; | |
318 | case 'd': /* d= AMS domain */ | |
319 | if (*s != '=') return US"d tag val"; | |
320 | if (arc_insert_tagvalue(al, offsetof(arc_line, d), &s)) return US"d tag dup"; | |
321 | break; | |
322 | case 'h': /* h= AMS headers */ | |
323 | if (*s != '=') return US"h tag val"; | |
324 | if (arc_insert_tagvalue(al, offsetof(arc_line, h), &s)) return US"h tag dup"; | |
325 | break; | |
326 | case 'i': /* i= ARC set instance */ | |
327 | if (*s != '=') return US"i tag val"; | |
328 | if (arc_insert_tagvalue(al, offsetof(arc_line, i), &s)) return US"i tag dup"; | |
329 | if (instance_only) goto done; | |
330 | break; | |
331 | case 'l': /* l= bodylength */ | |
332 | if (*s != '=') return US"l tag val"; | |
333 | if (arc_insert_tagvalue(al, offsetof(arc_line, l), &s)) return US"l tag dup"; | |
334 | break; | |
335 | case 's': /* s= AMS selector */ | |
336 | if (*s != '=') return US"s tag val"; | |
337 | if (arc_insert_tagvalue(al, offsetof(arc_line, s), &s)) return US"s tag dup"; | |
338 | break; | |
339 | } | |
340 | ||
341 | while ((c = *s) && c != ';') s++; | |
342 | if (c) s++; /* ; after tag-spec */ | |
343 | ||
344 | /* for all but the b= tag, copy the field including FWS. For the b=, | |
345 | drop the tag content. */ | |
346 | ||
347 | if (!instance_only) | |
348 | if (bstart) | |
349 | { | |
350 | size_t n = bstart - fieldstart; | |
351 | memcpy(r, fieldstart, n); /* FWS "b=" */ | |
352 | r += n; | |
353 | al->rawsig_no_b_val.len += n; | |
354 | n = s - bend; | |
355 | memcpy(r, bend, n); /* FWS ";" */ | |
356 | r += n; | |
357 | al->rawsig_no_b_val.len += n; | |
358 | } | |
359 | else | |
360 | { | |
361 | size_t n = s - fieldstart; | |
362 | memcpy(r, fieldstart, n); | |
363 | r += n; | |
364 | al->rawsig_no_b_val.len += n; | |
365 | } | |
366 | } | |
367 | ||
368 | if (!instance_only) | |
369 | *r = '\0'; | |
370 | ||
371 | done: | |
372 | /* debug_printf("%s: finshed\n", __FUNCTION__); */ | |
373 | return NULL; | |
374 | } | |
375 | ||
376 | ||
377 | /* Insert one header line in the correct set of the chain, | |
378 | adding instances as needed and checking for duplicate lines. | |
379 | */ | |
380 | ||
381 | static uschar * | |
382 | arc_insert_hdr(arc_ctx * ctx, header_line * h, unsigned off, unsigned hoff, | |
383 | BOOL instance_only) | |
384 | { | |
385 | int i; | |
386 | arc_set * as; | |
387 | arc_line * al = store_get(sizeof(arc_line)), ** alp; | |
388 | uschar * e; | |
389 | ||
390 | memset(al, 0, sizeof(arc_line)); | |
391 | ||
392 | if ((e = arc_parse_line(al, h, off, instance_only))) | |
393 | { | |
394 | DEBUG(D_acl) if (e) debug_printf("ARC: %s\n", e); | |
395 | return US"line parse"; | |
396 | } | |
397 | if (!(i = arc_instance_from_hdr(al))) return US"instance find"; | |
398 | if (!(as = arc_find_set(ctx, i))) return US"set find"; | |
399 | if (*(alp = (arc_line **)(US as + hoff))) return US"dup hdr"; | |
400 | ||
401 | *alp = al; | |
402 | return NULL; | |
403 | } | |
404 | ||
405 | ||
406 | ||
407 | ||
408 | static const uschar * | |
409 | arc_try_header(arc_ctx * ctx, header_line * h, BOOL instance_only) | |
410 | { | |
411 | const uschar * e; | |
412 | ||
413 | /*debug_printf("consider hdr '%s'\n", h->text);*/ | |
414 | if (strncmpic(ARC_HDR_AAR, h->text, ARC_HDRLEN_AAR) == 0) | |
415 | { | |
416 | DEBUG(D_acl) | |
417 | { | |
418 | int len = h->slen; | |
419 | uschar * s; | |
420 | for (s = h->text + h->slen; s[-1] == '\r' || s[-1] == '\n'; ) | |
421 | s--, len--; | |
422 | debug_printf("ARC: found AAR: %.*s\n", len, h->text); | |
423 | } | |
424 | if ((e = arc_insert_hdr(ctx, h, ARC_HDRLEN_AAR, offsetof(arc_set, hdr_aar), | |
425 | TRUE))) | |
426 | { | |
427 | DEBUG(D_acl) debug_printf("inserting AAR: %s\n", e); | |
428 | return US"inserting AAR"; | |
429 | } | |
430 | } | |
431 | else if (strncmpic(ARC_HDR_AMS, h->text, ARC_HDRLEN_AMS) == 0) | |
432 | { | |
433 | arc_line * ams; | |
434 | ||
435 | DEBUG(D_acl) | |
436 | { | |
437 | int len = h->slen; | |
438 | uschar * s; | |
439 | for (s = h->text + h->slen; s[-1] == '\r' || s[-1] == '\n'; ) | |
440 | s--, len--; | |
441 | debug_printf("ARC: found AMS: %.*s\n", len, h->text); | |
442 | } | |
443 | if ((e = arc_insert_hdr(ctx, h, ARC_HDRLEN_AMS, offsetof(arc_set, hdr_ams), | |
444 | instance_only))) | |
445 | { | |
446 | DEBUG(D_acl) debug_printf("inserting AMS: %s\n", e); | |
447 | return US"inserting AMS"; | |
448 | } | |
449 | ||
450 | /* defaults */ | |
451 | /*XXX dubious selection of ams here */ | |
452 | ams = ctx->arcset_chain->hdr_ams; | |
453 | if (!ams->c.data) | |
454 | { | |
455 | ams->c_head.data = US"simple"; ams->c_head.len = 6; | |
456 | ams->c_body = ams->c_head; | |
457 | } | |
458 | } | |
459 | else if (strncmpic(ARC_HDR_AS, h->text, ARC_HDRLEN_AS) == 0) | |
460 | { | |
461 | DEBUG(D_acl) | |
462 | { | |
463 | int len = h->slen; | |
464 | uschar * s; | |
465 | for (s = h->text + h->slen; s[-1] == '\r' || s[-1] == '\n'; ) | |
466 | s--, len--; | |
467 | debug_printf("ARC: found AS: %.*s\n", len, h->text); | |
468 | } | |
469 | if ((e = arc_insert_hdr(ctx, h, ARC_HDRLEN_AS, offsetof(arc_set, hdr_as), | |
470 | instance_only))) | |
471 | { | |
472 | DEBUG(D_acl) debug_printf("inserting AS: %s\n", e); | |
473 | return US"inserting AS"; | |
474 | } | |
475 | } | |
476 | return NULL; | |
477 | } | |
478 | ||
479 | ||
480 | ||
481 | /* Gather the chain of arc sets from the headers. | |
482 | Check for duplicates while that is done. Also build the | |
483 | reverse-order headers list; | |
484 | ||
485 | Return: ARC state if determined, eg. by lack of any ARC chain. | |
486 | */ | |
487 | ||
488 | static const uschar * | |
489 | arc_vfy_collect_hdrs(arc_ctx * ctx) | |
490 | { | |
491 | header_line * h; | |
978e78de | 492 | hdr_rlist * r = NULL, * rprev = NULL; |
617d3932 JH |
493 | const uschar * e; |
494 | ||
495 | DEBUG(D_acl) debug_printf("ARC: collecting arc sets\n"); | |
496 | for (h = header_list; h; h = h->next) | |
497 | { | |
498 | r = store_get(sizeof(hdr_rlist)); | |
499 | r->prev = rprev; | |
500 | r->used = FALSE; | |
501 | r->h = h; | |
502 | rprev = r; | |
503 | ||
504 | if ((e = arc_try_header(ctx, h, FALSE))) | |
93c931f8 JH |
505 | { |
506 | arc_state_reason = string_sprintf("collecting headers: %s", e); | |
507 | return US"fail"; | |
508 | } | |
617d3932 JH |
509 | } |
510 | headers_rlist = r; | |
511 | ||
512 | if (!ctx->arcset_chain) return US"none"; | |
513 | return NULL; | |
514 | } | |
515 | ||
516 | ||
517 | static BOOL | |
518 | arc_cv_match(arc_line * al, const uschar * s) | |
519 | { | |
520 | return Ustrncmp(s, al->cv.data, al->cv.len) == 0; | |
521 | } | |
522 | ||
523 | /******************************************************************************/ | |
524 | ||
525 | /* Return the hash of headers from the message that the AMS claims it | |
526 | signed. | |
527 | */ | |
528 | ||
529 | static void | |
530 | arc_get_verify_hhash(arc_ctx * ctx, arc_line * ams, blob * hhash) | |
531 | { | |
532 | const uschar * headernames = string_copyn(ams->h.data, ams->h.len); | |
533 | const uschar * hn; | |
534 | int sep = ':'; | |
535 | hdr_rlist * r; | |
536 | BOOL relaxed = Ustrncmp(US"relaxed", ams->c_head.data, ams->c_head.len) == 0; | |
537 | int hashtype = pdkim_hashname_to_hashtype( | |
538 | ams->a_hash.data, ams->a_hash.len); | |
539 | hctx hhash_ctx; | |
540 | const uschar * s; | |
541 | int len; | |
542 | ||
543 | if (!exim_sha_init(&hhash_ctx, pdkim_hashes[hashtype].exim_hashmethod)) | |
544 | { | |
545 | DEBUG(D_acl) | |
546 | debug_printf("ARC: hash setup error, possibly nonhandled hashtype\n"); | |
547 | return; | |
548 | } | |
549 | ||
550 | /* For each headername in the list from the AMS (walking in order) | |
551 | walk the message headers in reverse order, adding to the hash any | |
552 | found for the first time. For that last point, maintain used-marks | |
553 | on the list of message headers. */ | |
554 | ||
555 | DEBUG(D_acl) debug_printf("ARC: AMS header data for verification:\n"); | |
556 | ||
557 | for (r = headers_rlist; r; r = r->prev) | |
558 | r->used = FALSE; | |
559 | while ((hn = string_nextinlist(&headernames, &sep, NULL, 0))) | |
560 | for (r = headers_rlist; r; r = r->prev) | |
561 | if ( !r->used | |
562 | && strncasecmp(CCS (s = r->h->text), CCS hn, Ustrlen(hn)) == 0 | |
563 | ) | |
564 | { | |
565 | if (relaxed) s = pdkim_relax_header_n(s, r->h->slen, TRUE); | |
566 | ||
567 | len = Ustrlen(s); | |
568 | DEBUG(D_acl) pdkim_quoteprint(s, len); | |
569 | exim_sha_update(&hhash_ctx, s, Ustrlen(s)); | |
570 | r->used = TRUE; | |
571 | break; | |
572 | } | |
573 | ||
d9604f37 | 574 | /* Finally add in the signature header (with the b= tag stripped); no CRLF */ |
617d3932 JH |
575 | |
576 | s = ams->rawsig_no_b_val.data, len = ams->rawsig_no_b_val.len; | |
577 | if (relaxed) | |
d9604f37 | 578 | len = Ustrlen(s = pdkim_relax_header_n(s, len, FALSE)); |
617d3932 JH |
579 | DEBUG(D_acl) pdkim_quoteprint(s, len); |
580 | exim_sha_update(&hhash_ctx, s, len); | |
581 | ||
582 | exim_sha_finish(&hhash_ctx, hhash); | |
583 | DEBUG(D_acl) | |
584 | { debug_printf("ARC: header hash: "); pdkim_hexprint(hhash->data, hhash->len); } | |
585 | return; | |
586 | } | |
587 | ||
588 | ||
589 | ||
590 | ||
591 | static pdkim_pubkey * | |
592 | arc_line_to_pubkey(arc_line * al) | |
593 | { | |
594 | uschar * dns_txt; | |
595 | pdkim_pubkey * p; | |
596 | ||
597 | if (!(dns_txt = dkim_exim_query_dns_txt(string_sprintf("%.*s._domainkey.%.*s", | |
598 | al->s.len, al->s.data, al->d.len, al->d.data)))) | |
599 | { | |
600 | DEBUG(D_acl) debug_printf("pubkey dns lookup fail\n"); | |
601 | return NULL; | |
602 | } | |
603 | ||
604 | if ( !(p = pdkim_parse_pubkey_record(dns_txt)) | |
605 | || (Ustrcmp(p->srvtype, "*") != 0 && Ustrcmp(p->srvtype, "email") != 0) | |
606 | ) | |
607 | { | |
608 | DEBUG(D_acl) debug_printf("pubkey dns lookup format error\n"); | |
609 | return NULL; | |
610 | } | |
611 | ||
612 | /* If the pubkey limits use to specified hashes, reject unusable | |
613 | signatures. XXX should we have looked for multiple dns records? */ | |
614 | ||
615 | if (p->hashes) | |
616 | { | |
617 | const uschar * list = p->hashes, * ele; | |
618 | int sep = ':'; | |
619 | ||
620 | while ((ele = string_nextinlist(&list, &sep, NULL, 0))) | |
621 | if (Ustrncmp(ele, al->a_hash.data, al->a_hash.len) == 0) break; | |
622 | if (!ele) | |
623 | { | |
624 | DEBUG(D_acl) debug_printf("pubkey h=%s vs sig a=%.*s\n", | |
978e78de | 625 | p->hashes, (int)al->a.len, al->a.data); |
617d3932 JH |
626 | return NULL; |
627 | } | |
628 | } | |
629 | return p; | |
630 | } | |
631 | ||
632 | ||
633 | ||
634 | ||
635 | static pdkim_bodyhash * | |
636 | arc_ams_setup_vfy_bodyhash(arc_line * ams) | |
637 | { | |
638 | int canon_head, canon_body; | |
639 | long bodylen; | |
640 | ||
b3d9ebf5 | 641 | if (!ams->c.data) ams->c.data = US"simple"; /* RFC 6376 (DKIM) default */ |
617d3932 JH |
642 | pdkim_cstring_to_canons(ams->c.data, ams->c.len, &canon_head, &canon_body); |
643 | bodylen = ams->l.data | |
644 | ? strtol(CS string_copyn(ams->l.data, ams->l.len), NULL, 10) : -1; | |
645 | ||
646 | return pdkim_set_bodyhash(dkim_verify_ctx, | |
647 | pdkim_hashname_to_hashtype(ams->a_hash.data, ams->a_hash.len), | |
648 | canon_body, | |
649 | bodylen); | |
650 | } | |
651 | ||
652 | ||
653 | ||
654 | /* Verify an AMS. This is a DKIM-sig header, but with an ARC i= tag | |
655 | and without a DKIM v= tag. | |
656 | */ | |
657 | ||
93c931f8 | 658 | static const uschar * |
617d3932 JH |
659 | arc_ams_verify(arc_ctx * ctx, arc_set * as) |
660 | { | |
661 | arc_line * ams = as->hdr_ams; | |
662 | pdkim_bodyhash * b; | |
663 | pdkim_pubkey * p; | |
664 | blob sighash; | |
665 | blob hhash; | |
666 | ev_ctx vctx; | |
667 | int hashtype; | |
668 | const uschar * errstr; | |
669 | ||
93c931f8 | 670 | as->ams_verify_done = US"in-progress"; |
617d3932 JH |
671 | |
672 | /* Check the AMS has all the required tags: | |
673 | "a=" algorithm | |
674 | "b=" signature | |
675 | "bh=" body hash | |
676 | "d=" domain (for key lookup) | |
677 | "h=" headers (included in signature) | |
678 | "s=" key-selector (for key lookup) | |
679 | */ | |
680 | if ( !ams->a.data || !ams->b.data || !ams->bh.data || !ams->d.data | |
681 | || !ams->h.data || !ams->s.data) | |
93c931f8 JH |
682 | { |
683 | as->ams_verify_done = arc_state_reason = US"required tag missing"; | |
617d3932 | 684 | return US"fail"; |
93c931f8 | 685 | } |
617d3932 JH |
686 | |
687 | ||
688 | /* The bodyhash should have been created earlier, and the dkim code should | |
689 | have managed calculating it during message input. Find the reference to it. */ | |
690 | ||
691 | if (!(b = arc_ams_setup_vfy_bodyhash(ams))) | |
93c931f8 JH |
692 | { |
693 | as->ams_verify_done = arc_state_reason = US"internal hash setup error"; | |
617d3932 | 694 | return US"fail"; |
93c931f8 | 695 | } |
617d3932 JH |
696 | |
697 | DEBUG(D_acl) | |
698 | { | |
699 | debug_printf("ARC i=%d AMS Body bytes hashed: %lu\n" | |
700 | " Body %.*s computed: ", | |
701 | as->instance, b->signed_body_bytes, | |
978e78de | 702 | (int)ams->a_hash.len, ams->a_hash.data); |
617d3932 JH |
703 | pdkim_hexprint(CUS b->bh.data, b->bh.len); |
704 | } | |
705 | ||
706 | /* We know the bh-tag blob is of a nul-term string, so safe as a string */ | |
707 | ||
708 | if ( !ams->bh.data | |
709 | || (pdkim_decode_base64(ams->bh.data, &sighash), sighash.len != b->bh.len) | |
710 | || memcmp(sighash.data, b->bh.data, b->bh.len) != 0 | |
711 | ) | |
712 | { | |
713 | DEBUG(D_acl) | |
714 | { | |
715 | debug_printf("ARC i=%d AMS Body hash from headers: ", as->instance); | |
716 | pdkim_hexprint(sighash.data, sighash.len); | |
717 | debug_printf("ARC i=%d AMS Body hash did NOT match\n", as->instance); | |
718 | } | |
93c931f8 | 719 | return as->ams_verify_done = arc_state_reason = US"AMS body hash miscompare"; |
617d3932 JH |
720 | } |
721 | ||
722 | DEBUG(D_acl) debug_printf("ARC i=%d AMS Body hash compared OK\n", as->instance); | |
723 | ||
724 | /* Get the public key from DNS */ | |
725 | ||
726 | if (!(p = arc_line_to_pubkey(ams))) | |
93c931f8 | 727 | return as->ams_verify_done = arc_state_reason = US"pubkey problem"; |
617d3932 JH |
728 | |
729 | /* We know the b-tag blob is of a nul-term string, so safe as a string */ | |
730 | pdkim_decode_base64(ams->b.data, &sighash); | |
731 | ||
732 | arc_get_verify_hhash(ctx, ams, &hhash); | |
733 | ||
734 | /* Setup the interface to the signing library */ | |
735 | ||
736 | if ((errstr = exim_dkim_verify_init(&p->key, KEYFMT_DER, &vctx))) | |
737 | { | |
738 | DEBUG(D_acl) debug_printf("ARC verify init: %s\n", errstr); | |
93c931f8 | 739 | as->ams_verify_done = arc_state_reason = US"internal sigverify init error"; |
617d3932 JH |
740 | return US"fail"; |
741 | } | |
742 | ||
743 | hashtype = pdkim_hashname_to_hashtype(ams->a_hash.data, ams->a_hash.len); | |
744 | ||
745 | if ((errstr = exim_dkim_verify(&vctx, | |
746 | pdkim_hashes[hashtype].exim_hashmethod, &hhash, &sighash))) | |
747 | { | |
748 | DEBUG(D_acl) debug_printf("ARC i=%d AMS verify %s\n", as->instance, errstr); | |
93c931f8 | 749 | return as->ams_verify_done = arc_state_reason = US"AMS sig nonverify"; |
617d3932 JH |
750 | } |
751 | ||
752 | DEBUG(D_acl) debug_printf("ARC i=%d AMS verify pass\n", as->instance); | |
753 | as->ams_verify_passed = TRUE; | |
754 | return NULL; | |
755 | } | |
756 | ||
757 | ||
758 | ||
759 | /* Check the sets are instance-continuous and that all | |
760 | members are present. Check that no arc_seals are "fail". | |
761 | Set the highest instance number global. | |
762 | Verify the latest AMS. | |
763 | */ | |
764 | static uschar * | |
765 | arc_headers_check(arc_ctx * ctx) | |
766 | { | |
767 | arc_set * as; | |
768 | int inst; | |
769 | BOOL ams_fail_found = FALSE; | |
617d3932 JH |
770 | |
771 | if (!(as = ctx->arcset_chain)) | |
772 | return US"none"; | |
773 | ||
774 | for(inst = 0; as; as = as->next) | |
775 | { | |
776 | if ( as->instance != ++inst | |
777 | || !as->hdr_aar || !as->hdr_ams || !as->hdr_as | |
778 | || arc_cv_match(as->hdr_as, US"fail") | |
779 | ) | |
780 | { | |
b3d9ebf5 | 781 | arc_state_reason = string_sprintf("i=%d" |
93c931f8 | 782 | " (cv, sequence or missing header)", as->instance); |
b3d9ebf5 JH |
783 | DEBUG(D_acl) debug_printf("ARC chain fail at %s\n", arc_state_reason); |
784 | return US"fail"; | |
617d3932 JH |
785 | } |
786 | ||
787 | /* Evaluate the oldest-pass AMS validation while we're here. | |
788 | It does not affect the AS chain validation but is reported as | |
789 | auxilary info. */ | |
790 | ||
791 | if (!ams_fail_found) | |
792 | if (arc_ams_verify(ctx, as)) | |
793 | ams_fail_found = TRUE; | |
794 | else | |
795 | arc_oldest_pass = inst; | |
93c931f8 | 796 | arc_state_reason = NULL; |
617d3932 JH |
797 | } |
798 | ||
799 | arc_received = ctx->arcset_chain_last; | |
800 | arc_received_instance = inst; | |
617d3932 JH |
801 | |
802 | /* We can skip the latest-AMS validation, if we already did it. */ | |
803 | ||
804 | as = ctx->arcset_chain_last; | |
3c676fa8 | 805 | if (!as->ams_verify_passed) |
93c931f8 | 806 | { |
3c676fa8 JH |
807 | if (as->ams_verify_done) |
808 | { | |
809 | arc_state_reason = as->ams_verify_done; | |
810 | return US"fail"; | |
811 | } | |
812 | if (!!arc_ams_verify(ctx, as)) | |
813 | return US"fail"; | |
93c931f8 | 814 | } |
617d3932 JH |
815 | return NULL; |
816 | } | |
817 | ||
818 | ||
819 | /******************************************************************************/ | |
820 | static const uschar * | |
821 | arc_seal_verify(arc_ctx * ctx, arc_set * as) | |
822 | { | |
823 | arc_line * hdr_as = as->hdr_as; | |
824 | arc_set * as2; | |
825 | int hashtype; | |
826 | hctx hhash_ctx; | |
827 | blob hhash_computed; | |
828 | blob sighash; | |
829 | ev_ctx vctx; | |
830 | pdkim_pubkey * p; | |
831 | const uschar * errstr; | |
832 | ||
833 | DEBUG(D_acl) debug_printf("ARC: AS vfy i=%d\n", as->instance); | |
834 | /* | |
835 | 1. If the value of the "cv" tag on that seal is "fail", the | |
836 | chain state is "fail" and the algorithm stops here. (This | |
837 | step SHOULD be skipped if the earlier step (2.1) was | |
838 | performed) [it was] | |
839 | ||
840 | 2. In Boolean nomenclature: if ((i == 1 && cv != "none") or (cv | |
841 | == "none" && i != 1)) then the chain state is "fail" and the | |
842 | algorithm stops here (note that the ordering of the logic is | |
843 | structured for short-circuit evaluation). | |
844 | */ | |
845 | ||
846 | if ( as->instance == 1 && !arc_cv_match(hdr_as, US"none") | |
847 | || arc_cv_match(hdr_as, US"none") && as->instance != 1 | |
848 | ) | |
93c931f8 JH |
849 | { |
850 | arc_state_reason = US"seal cv state"; | |
617d3932 | 851 | return US"fail"; |
93c931f8 | 852 | } |
617d3932 JH |
853 | |
854 | /* | |
855 | 3. Initialize a hash function corresponding to the "a" tag of | |
856 | the ARC-Seal. | |
857 | */ | |
858 | ||
859 | hashtype = pdkim_hashname_to_hashtype(hdr_as->a_hash.data, hdr_as->a_hash.len); | |
860 | ||
861 | if (!exim_sha_init(&hhash_ctx, pdkim_hashes[hashtype].exim_hashmethod)) | |
862 | { | |
863 | DEBUG(D_acl) | |
864 | debug_printf("ARC: hash setup error, possibly nonhandled hashtype\n"); | |
93c931f8 | 865 | arc_state_reason = US"seal hash setup error"; |
617d3932 JH |
866 | return US"fail"; |
867 | } | |
868 | ||
869 | /* | |
870 | 4. Compute the canonicalized form of the ARC header fields, in | |
871 | the order described in Section 5.4.2, using the "relaxed" | |
872 | header canonicalization defined in Section 3.4.2 of | |
873 | [RFC6376]. Pass the canonicalized result to the hash | |
874 | function. | |
d9604f37 JH |
875 | |
876 | Headers are CRLF-separated, but the last one is not crlf-terminated. | |
617d3932 JH |
877 | */ |
878 | ||
879 | DEBUG(D_acl) debug_printf("ARC: AS header data for verification:\n"); | |
880 | for (as2 = ctx->arcset_chain; | |
881 | as2 && as2->instance <= as->instance; | |
882 | as2 = as2->next) | |
883 | { | |
884 | arc_line * al; | |
885 | uschar * s; | |
886 | int len; | |
887 | ||
888 | al = as2->hdr_aar; | |
889 | if (!(s = al->relaxed)) | |
890 | al->relaxed = s = pdkim_relax_header_n(al->complete->text, | |
891 | al->complete->slen, TRUE); | |
892 | len = Ustrlen(s); | |
893 | DEBUG(D_acl) pdkim_quoteprint(s, len); | |
894 | exim_sha_update(&hhash_ctx, s, len); | |
895 | ||
896 | al = as2->hdr_ams; | |
897 | if (!(s = al->relaxed)) | |
898 | al->relaxed = s = pdkim_relax_header_n(al->complete->text, | |
899 | al->complete->slen, TRUE); | |
900 | len = Ustrlen(s); | |
901 | DEBUG(D_acl) pdkim_quoteprint(s, len); | |
902 | exim_sha_update(&hhash_ctx, s, len); | |
903 | ||
904 | al = as2->hdr_as; | |
905 | if (as2->instance == as->instance) | |
906 | s = pdkim_relax_header_n(al->rawsig_no_b_val.data, | |
d9604f37 | 907 | al->rawsig_no_b_val.len, FALSE); |
617d3932 JH |
908 | else if (!(s = al->relaxed)) |
909 | al->relaxed = s = pdkim_relax_header_n(al->complete->text, | |
910 | al->complete->slen, TRUE); | |
911 | len = Ustrlen(s); | |
912 | DEBUG(D_acl) pdkim_quoteprint(s, len); | |
913 | exim_sha_update(&hhash_ctx, s, len); | |
914 | } | |
915 | ||
916 | /* | |
917 | 5. Retrieve the final digest from the hash function. | |
918 | */ | |
919 | ||
920 | exim_sha_finish(&hhash_ctx, &hhash_computed); | |
921 | DEBUG(D_acl) | |
922 | { | |
923 | debug_printf("ARC i=%d AS Header %.*s computed: ", | |
978e78de | 924 | as->instance, (int)hdr_as->a_hash.len, hdr_as->a_hash.data); |
617d3932 JH |
925 | pdkim_hexprint(hhash_computed.data, hhash_computed.len); |
926 | } | |
927 | ||
928 | ||
929 | /* | |
930 | 6. Retrieve the public key identified by the "s" and "d" tags in | |
931 | the ARC-Seal, as described in Section 4.1.6. | |
932 | */ | |
933 | ||
934 | if (!(p = arc_line_to_pubkey(hdr_as))) | |
935 | return US"pubkey problem"; | |
936 | ||
937 | /* | |
938 | 7. Determine whether the signature portion ("b" tag) of the ARC- | |
939 | Seal and the digest computed above are valid according to the | |
940 | public key. (See also Section Section 8.4 for failure case | |
941 | handling) | |
942 | ||
943 | 8. If the signature is not valid, the chain state is "fail" and | |
944 | the algorithm stops here. | |
945 | */ | |
946 | ||
947 | /* We know the b-tag blob is of a nul-term string, so safe as a string */ | |
948 | pdkim_decode_base64(hdr_as->b.data, &sighash); | |
949 | ||
950 | if ((errstr = exim_dkim_verify_init(&p->key, KEYFMT_DER, &vctx))) | |
951 | { | |
952 | DEBUG(D_acl) debug_printf("ARC verify init: %s\n", errstr); | |
953 | return US"fail"; | |
954 | } | |
955 | ||
956 | hashtype = pdkim_hashname_to_hashtype(hdr_as->a_hash.data, hdr_as->a_hash.len); | |
957 | ||
958 | if ((errstr = exim_dkim_verify(&vctx, | |
959 | pdkim_hashes[hashtype].exim_hashmethod, | |
960 | &hhash_computed, &sighash))) | |
961 | { | |
962 | DEBUG(D_acl) | |
963 | debug_printf("ARC i=%d AS headers verify: %s\n", as->instance, errstr); | |
d9604f37 | 964 | arc_state_reason = US"seal sigverify error"; |
617d3932 JH |
965 | return US"fail"; |
966 | } | |
967 | ||
968 | DEBUG(D_acl) debug_printf("ARC: AS vfy i=%d pass\n", as->instance); | |
969 | return NULL; | |
970 | } | |
971 | ||
972 | ||
973 | static const uschar * | |
974 | arc_verify_seals(arc_ctx * ctx) | |
975 | { | |
976 | arc_set * as = ctx->arcset_chain; | |
977 | ||
978 | if (!as) | |
979 | return US"none"; | |
980 | ||
981 | while (as) | |
982 | { | |
983 | if (arc_seal_verify(ctx, as)) return US"fail"; | |
984 | as = as->next; | |
985 | } | |
986 | DEBUG(D_acl) debug_printf("ARC: AS vfy overall pass\n"); | |
987 | return NULL; | |
988 | } | |
989 | /******************************************************************************/ | |
990 | ||
991 | /* Do ARC verification. Called from DATA ACL, on a verify = arc | |
992 | condition. No arguments; we are checking globals. | |
993 | ||
994 | Return: The ARC state, or NULL on error. | |
995 | */ | |
996 | ||
997 | const uschar * | |
998 | acl_verify_arc(void) | |
999 | { | |
1000 | arc_ctx ctx = { NULL }; | |
1001 | const uschar * res; | |
1002 | ||
311fbe57 JH |
1003 | if (!dkim_verify_ctx) |
1004 | { | |
1005 | DEBUG(D_acl) debug_printf("ARC: no DKIM verify context\n"); | |
1006 | return NULL; | |
1007 | } | |
1008 | ||
617d3932 JH |
1009 | /* AS evaluation, per |
1010 | https://tools.ietf.org/html/draft-ietf-dmarc-arc-protocol-10#section-6 | |
1011 | */ | |
1012 | /* 1. Collect all ARC sets currently on the message. If there were | |
1013 | none, the ARC state is "none" and the algorithm stops here. | |
1014 | */ | |
1015 | ||
1016 | if ((res = arc_vfy_collect_hdrs(&ctx))) | |
1017 | goto out; | |
1018 | ||
1019 | /* 2. If the form of any ARC set is invalid (e.g., does not contain | |
1020 | exactly one of each of the three ARC-specific header fields), | |
1021 | then the chain state is "fail" and the algorithm stops here. | |
1022 | ||
1023 | 1. To avoid the overhead of unnecessary computation and delay | |
1024 | from crypto and DNS operations, the cv value for all ARC- | |
1025 | Seal(s) MAY be checked at this point. If any of the values | |
1026 | are "fail", then the overall state of the chain is "fail" and | |
1027 | the algorithm stops here. | |
1028 | ||
1029 | 3. Conduct verification of the ARC-Message-Signature header field | |
1030 | bearing the highest instance number. If this verification fails, | |
1031 | then the chain state is "fail" and the algorithm stops here. | |
1032 | */ | |
1033 | ||
1034 | if ((res = arc_headers_check(&ctx))) | |
1035 | goto out; | |
1036 | ||
1037 | /* 4. For each ARC-Seal from the "N"th instance to the first, apply the | |
1038 | following logic: | |
1039 | ||
1040 | 1. If the value of the "cv" tag on that seal is "fail", the | |
1041 | chain state is "fail" and the algorithm stops here. (This | |
1042 | step SHOULD be skipped if the earlier step (2.1) was | |
1043 | performed) | |
1044 | ||
1045 | 2. In Boolean nomenclature: if ((i == 1 && cv != "none") or (cv | |
1046 | == "none" && i != 1)) then the chain state is "fail" and the | |
1047 | algorithm stops here (note that the ordering of the logic is | |
1048 | structured for short-circuit evaluation). | |
1049 | ||
1050 | 3. Initialize a hash function corresponding to the "a" tag of | |
1051 | the ARC-Seal. | |
1052 | ||
1053 | 4. Compute the canonicalized form of the ARC header fields, in | |
1054 | the order described in Section 5.4.2, using the "relaxed" | |
1055 | header canonicalization defined in Section 3.4.2 of | |
1056 | [RFC6376]. Pass the canonicalized result to the hash | |
1057 | function. | |
1058 | ||
1059 | 5. Retrieve the final digest from the hash function. | |
1060 | ||
1061 | 6. Retrieve the public key identified by the "s" and "d" tags in | |
1062 | the ARC-Seal, as described in Section 4.1.6. | |
1063 | ||
1064 | 7. Determine whether the signature portion ("b" tag) of the ARC- | |
1065 | Seal and the digest computed above are valid according to the | |
1066 | public key. (See also Section Section 8.4 for failure case | |
1067 | handling) | |
1068 | ||
1069 | 8. If the signature is not valid, the chain state is "fail" and | |
1070 | the algorithm stops here. | |
1071 | ||
1072 | 5. If all seals pass validation, then the chain state is "pass", and | |
1073 | the algorithm is complete. | |
1074 | */ | |
1075 | ||
1076 | if ((res = arc_verify_seals(&ctx))) | |
1077 | goto out; | |
1078 | ||
1079 | res = US"pass"; | |
1080 | ||
1081 | out: | |
1082 | return res; | |
1083 | } | |
1084 | ||
1085 | /******************************************************************************/ | |
1086 | ||
1087 | /* Prepend the header to the rlist */ | |
1088 | ||
1089 | static hdr_rlist * | |
1090 | arc_rlist_entry(hdr_rlist * list, const uschar * s, int len) | |
1091 | { | |
1092 | hdr_rlist * r = store_get(sizeof(hdr_rlist) + sizeof(header_line)); | |
1093 | header_line * h = r->h = (header_line *)(r+1); | |
1094 | ||
1095 | r->prev = list; | |
1096 | r->used = FALSE; | |
1097 | h->next = NULL; | |
1098 | h->type = 0; | |
1099 | h->slen = len; | |
1100 | h->text = US s; | |
1101 | ||
1102 | /* This works for either NL or CRLF lines; also nul-termination */ | |
1103 | while (*++s) | |
1104 | if (*s == '\n' && s[1] != '\t' && s[1] != ' ') break; | |
1105 | s++; /* move past end of line */ | |
1106 | ||
1107 | return r; | |
1108 | } | |
1109 | ||
1110 | ||
1111 | /* Walk the given headers strings identifying each header, and construct | |
b3d9ebf5 | 1112 | a reverse-order list. |
617d3932 JH |
1113 | */ |
1114 | ||
1115 | static hdr_rlist * | |
1116 | arc_sign_scan_headers(arc_ctx * ctx, gstring * sigheaders) | |
1117 | { | |
1118 | const uschar * s; | |
1119 | hdr_rlist * rheaders = NULL; | |
1120 | ||
1121 | s = sigheaders ? sigheaders->s : NULL; | |
1122 | if (s) while (*s) | |
1123 | { | |
978e78de | 1124 | const uschar * s2 = s; |
617d3932 JH |
1125 | |
1126 | /* This works for either NL or CRLF lines; also nul-termination */ | |
1127 | while (*++s2) | |
1128 | if (*s2 == '\n' && s2[1] != '\t' && s2[1] != ' ') break; | |
1129 | s2++; /* move past end of line */ | |
1130 | ||
1131 | rheaders = arc_rlist_entry(rheaders, s, s2 - s); | |
1132 | s = s2; | |
1133 | } | |
1134 | return rheaders; | |
1135 | } | |
1136 | ||
1137 | ||
1138 | ||
1139 | /* Return the A-R content, without identity, with line-ending and | |
1140 | NUL termination. */ | |
1141 | ||
1142 | static BOOL | |
1143 | arc_sign_find_ar(header_line * headers, const uschar * identity, blob * ret) | |
1144 | { | |
1145 | header_line * h; | |
1146 | int ilen = Ustrlen(identity); | |
1147 | ||
1148 | ret->data = NULL; | |
1149 | for(h = headers; h; h = h->next) | |
1150 | { | |
1151 | uschar * s = h->text, c; | |
1152 | int len = h->slen; | |
1153 | ||
1154 | if (Ustrncmp(s, HDR_AR, HDRLEN_AR) != 0) continue; | |
1155 | s += HDRLEN_AR, len -= HDRLEN_AR; /* header name */ | |
1156 | while ( len > 0 | |
1157 | && (c = *s) && (c == ' ' || c == '\t' || c == '\r' || c == '\n')) | |
1158 | s++, len--; /* FWS */ | |
1159 | if (Ustrncmp(s, identity, ilen) != 0) continue; | |
1160 | s += ilen; len -= ilen; /* identity */ | |
1161 | if (len <= 0) continue; | |
1162 | if ((c = *s) && c == ';') s++, len--; /* identity terminator */ | |
1163 | while ( len > 0 | |
1164 | && (c = *s) && (c == ' ' || c == '\t' || c == '\r' || c == '\n')) | |
1165 | s++, len--; /* FWS */ | |
1166 | if (len <= 0) continue; | |
1167 | ret->data = s; | |
1168 | ret->len = len; | |
1169 | return TRUE; | |
1170 | } | |
1171 | return FALSE; | |
1172 | } | |
1173 | ||
1174 | ||
1175 | ||
1176 | /* Append a constructed AAR including CRLF. Add it to the arc_ctx too. */ | |
1177 | ||
1178 | static gstring * | |
1179 | arc_sign_append_aar(gstring * g, arc_ctx * ctx, | |
1180 | const uschar * identity, int instance, blob * ar) | |
1181 | { | |
1182 | int aar_off = g ? g->ptr : 0; | |
1183 | arc_set * as = store_get(sizeof(arc_set) + sizeof(arc_line) + sizeof(header_line)); | |
1184 | arc_line * al = (arc_line *)(as+1); | |
1185 | header_line * h = (header_line *)(al+1); | |
1186 | ||
1187 | g = string_catn(g, ARC_HDR_AAR, ARC_HDRLEN_AAR); | |
1188 | g = string_cat(g, string_sprintf(" i=%d; %s;\r\n\t", instance, identity)); | |
1189 | g = string_catn(g, US ar->data, ar->len); | |
1190 | ||
1191 | h->slen = g->ptr - aar_off; | |
1192 | h->text = g->s + aar_off; | |
1193 | al->complete = h; | |
1194 | as->next = NULL; | |
1195 | as->prev = ctx->arcset_chain_last; | |
1196 | as->instance = instance; | |
1197 | as->hdr_aar = al; | |
1198 | if (instance == 1) | |
1199 | ctx->arcset_chain = as; | |
1200 | else | |
1201 | ctx->arcset_chain_last->next = as; | |
1202 | ctx->arcset_chain_last = as; | |
1203 | ||
1204 | DEBUG(D_transport) debug_printf("ARC: AAR '%.*s'\n", h->slen - 2, h->text); | |
1205 | return g; | |
1206 | } | |
1207 | ||
1208 | ||
1209 | ||
1210 | static BOOL | |
1211 | arc_sig_from_pseudoheader(gstring * hdata, int hashtype, const uschar * privkey, | |
1212 | blob * sig, const uschar * why) | |
1213 | { | |
1214 | hashmethod hm = /*sig->keytype == KEYTYPE_ED25519*/ FALSE | |
1215 | ? HASH_SHA2_512 : pdkim_hashes[hashtype].exim_hashmethod; | |
1216 | blob hhash; | |
1217 | es_ctx sctx; | |
1218 | const uschar * errstr; | |
1219 | ||
1220 | DEBUG(D_transport) | |
1221 | { | |
1222 | hctx hhash_ctx; | |
1223 | debug_printf("ARC: %s header data for signing:\n", why); | |
1224 | pdkim_quoteprint(hdata->s, hdata->ptr); | |
1225 | ||
1226 | (void) exim_sha_init(&hhash_ctx, pdkim_hashes[hashtype].exim_hashmethod); | |
1227 | exim_sha_update(&hhash_ctx, hdata->s, hdata->ptr); | |
1228 | exim_sha_finish(&hhash_ctx, &hhash); | |
1229 | debug_printf("ARC: header hash: "); pdkim_hexprint(hhash.data, hhash.len); | |
1230 | } | |
1231 | ||
1232 | if (FALSE /*need hash for Ed25519 or GCrypt signing*/ ) | |
1233 | { | |
1234 | hctx hhash_ctx; | |
1235 | (void) exim_sha_init(&hhash_ctx, pdkim_hashes[hashtype].exim_hashmethod); | |
1236 | exim_sha_update(&hhash_ctx, hdata->s, hdata->ptr); | |
1237 | exim_sha_finish(&hhash_ctx, &hhash); | |
1238 | } | |
1239 | else | |
1240 | { | |
1241 | hhash.data = hdata->s; | |
1242 | hhash.len = hdata->ptr; | |
1243 | } | |
1244 | ||
1245 | if ( (errstr = exim_dkim_signing_init(privkey, &sctx)) | |
1246 | || (errstr = exim_dkim_sign(&sctx, hm, &hhash, sig))) | |
1247 | { | |
c3d43245 | 1248 | log_write(0, LOG_MAIN, "ARC: %s signing: %s\n", why, errstr); |
617d3932 JH |
1249 | return FALSE; |
1250 | } | |
1251 | return TRUE; | |
1252 | } | |
1253 | ||
1254 | ||
1255 | ||
1256 | static gstring * | |
1257 | arc_sign_append_sig(gstring * g, blob * sig) | |
1258 | { | |
1259 | /*debug_printf("%s: raw sig ", __FUNCTION__); pdkim_hexprint(sig->data, sig->len);*/ | |
1260 | sig->data = pdkim_encode_base64(sig); | |
1261 | sig->len = Ustrlen(sig->data); | |
1262 | for (;;) | |
1263 | { | |
1264 | int len = MIN(sig->len, 74); | |
1265 | g = string_catn(g, sig->data, len); | |
1266 | if ((sig->len -= len) == 0) break; | |
1267 | sig->data += len; | |
1268 | g = string_catn(g, US"\r\n\t ", 5); | |
1269 | } | |
1270 | g = string_catn(g, US";\r\n", 3); | |
1271 | gstring_reset_unused(g); | |
1272 | string_from_gstring(g); | |
1273 | return g; | |
1274 | } | |
1275 | ||
1276 | ||
1277 | /* Append a constructed AMS including CRLF. Add it to the arc_ctx too. */ | |
1278 | ||
1279 | static gstring * | |
1280 | arc_sign_append_ams(gstring * g, arc_ctx * ctx, int instance, | |
1281 | const uschar * identity, const uschar * selector, blob * bodyhash, | |
a93dbf44 | 1282 | hdr_rlist * rheaders, const uschar * privkey, unsigned options) |
617d3932 JH |
1283 | { |
1284 | uschar * s; | |
1285 | gstring * hdata = NULL; | |
1286 | int col; | |
1287 | int hashtype = pdkim_hashname_to_hashtype(US"sha256", 6); /*XXX hardwired */ | |
1288 | blob sig; | |
1289 | int ams_off; | |
1290 | arc_line * al = store_get(sizeof(header_line) + sizeof(arc_line)); | |
1291 | header_line * h = (header_line *)(al+1); | |
1292 | ||
1293 | /* debug_printf("%s\n", __FUNCTION__); */ | |
1294 | ||
1295 | /* Construct the to-be-signed AMS pseudo-header: everything but the sig. */ | |
1296 | ||
1297 | ams_off = g->ptr; | |
a93dbf44 | 1298 | g = string_append(g, 7, |
617d3932 JH |
1299 | ARC_HDR_AMS, |
1300 | US" i=", string_sprintf("%d", instance), | |
1301 | US"; a=rsa-sha256; c=relaxed; d=", identity, /*XXX hardwired */ | |
a93dbf44 JH |
1302 | US"; s=", selector); |
1303 | if (options & ARC_SIGN_OPT_TSTAMP) | |
1304 | g = string_append(g, 2, | |
0e83c148 JH |
1305 | US"; t=", string_sprintf("%lu", (u_long)now)); |
1306 | if (options & ARC_SIGN_OPT_EXPIRE) | |
1307 | g = string_append(g, 2, | |
1308 | US"; x=", string_sprintf("%lu", (u_long)expire)); | |
a93dbf44 | 1309 | g = string_append(g, 3, |
617d3932 JH |
1310 | US";\r\n\tbh=", pdkim_encode_base64(bodyhash), |
1311 | US";\r\n\th="); | |
1312 | ||
1313 | for(col = 3; rheaders; rheaders = rheaders->prev) | |
1314 | { | |
1315 | const uschar * hnames = US"DKIM-Signature:" PDKIM_DEFAULT_SIGN_HEADERS; | |
1316 | uschar * name, * htext = rheaders->h->text; | |
1317 | int sep = ':'; | |
1318 | ||
1319 | /* Spot headers of interest */ | |
1320 | ||
1321 | while ((name = string_nextinlist(&hnames, &sep, NULL, 0))) | |
1322 | { | |
1323 | int len = Ustrlen(name); | |
1324 | if (strncasecmp(CCS htext, CCS name, len) == 0) | |
1325 | { | |
1326 | /* If too long, fold line in h= field */ | |
1327 | ||
1328 | if (col + len > 78) g = string_catn(g, US"\r\n\t ", 5), col = 3; | |
1329 | ||
1330 | /* Add name to h= list */ | |
1331 | ||
1332 | g = string_catn(g, name, len); | |
1333 | g = string_catn(g, US":", 1); | |
1334 | col += len + 1; | |
1335 | ||
1336 | /* Accumulate header for hashing/signing */ | |
1337 | ||
1338 | hdata = string_cat(hdata, | |
1339 | pdkim_relax_header_n(htext, rheaders->h->slen, TRUE)); /*XXX hardwired */ | |
1340 | break; | |
1341 | } | |
1342 | } | |
1343 | } | |
1344 | ||
1345 | /* Lose the last colon from the h= list */ | |
1346 | ||
1347 | if (g->s[g->ptr - 1] == ':') g->ptr--; | |
1348 | ||
1349 | g = string_catn(g, US";\r\n\tb=;", 7); | |
1350 | ||
1351 | /* Include the pseudo-header in the accumulation */ | |
617d3932 | 1352 | |
d9604f37 | 1353 | s = pdkim_relax_header_n(g->s + ams_off, g->ptr - ams_off, FALSE); |
617d3932 JH |
1354 | hdata = string_cat(hdata, s); |
1355 | ||
1356 | /* Calculate the signature from the accumulation */ | |
1357 | /*XXX does that need further relaxation? there are spaces embedded in the b= strings! */ | |
1358 | ||
1359 | if (!arc_sig_from_pseudoheader(hdata, hashtype, privkey, &sig, US"AMS")) | |
1360 | return NULL; | |
1361 | ||
1362 | /* Lose the trailing semicolon from the psuedo-header, and append the signature | |
1363 | (folded over lines) and termination to complete it. */ | |
1364 | ||
1365 | g->ptr--; | |
1366 | g = arc_sign_append_sig(g, &sig); | |
1367 | ||
1368 | h->slen = g->ptr - ams_off; | |
1369 | h->text = g->s + ams_off; | |
1370 | al->complete = h; | |
1371 | ctx->arcset_chain_last->hdr_ams = al; | |
1372 | ||
1373 | DEBUG(D_transport) debug_printf("ARC: AMS '%.*s'\n", h->slen - 2, h->text); | |
1374 | return g; | |
1375 | } | |
1376 | ||
1377 | ||
1378 | ||
1379 | /* Look for an arc= result in an A-R header blob. We know that its data | |
1380 | happens to be a NUL-term string. */ | |
1381 | ||
1382 | static uschar * | |
1383 | arc_ar_cv_status(blob * ar) | |
1384 | { | |
1385 | const uschar * resinfo = ar->data; | |
1386 | int sep = ';'; | |
1387 | uschar * methodspec, * s; | |
1388 | ||
1389 | while ((methodspec = string_nextinlist(&resinfo, &sep, NULL, 0))) | |
1390 | if (Ustrncmp(methodspec, US"arc=", 4) == 0) | |
1391 | { | |
1392 | uschar c; | |
1393 | for (s = methodspec += 4; | |
1394 | (c = *s) && c != ';' && c != ' ' && c != '\r' && c != '\n'; ) s++; | |
1395 | return string_copyn(methodspec, s - methodspec); | |
1396 | } | |
3d0a6e0f | 1397 | return US"none"; |
617d3932 JH |
1398 | } |
1399 | ||
1400 | ||
1401 | ||
1402 | /* Build the AS header and prepend it */ | |
1403 | ||
1404 | static gstring * | |
1405 | arc_sign_prepend_as(gstring * arcset_interim, arc_ctx * ctx, | |
1406 | int instance, const uschar * identity, const uschar * selector, blob * ar, | |
a93dbf44 | 1407 | const uschar * privkey, unsigned options) |
617d3932 JH |
1408 | { |
1409 | gstring * arcset; | |
1410 | arc_set * as; | |
1411 | uschar * status = arc_ar_cv_status(ar); | |
1412 | arc_line * al = store_get(sizeof(header_line) + sizeof(arc_line)); | |
1413 | header_line * h = (header_line *)(al+1); | |
617d3932 JH |
1414 | |
1415 | gstring * hdata = NULL; | |
1416 | int hashtype = pdkim_hashname_to_hashtype(US"sha256", 6); /*XXX hardwired */ | |
1417 | blob sig; | |
1418 | ||
1419 | /* | |
1420 | - Generate AS | |
1421 | - no body coverage | |
1422 | - no h= tag; implicit coverage | |
1423 | - arc status from A-R | |
1424 | - if fail: | |
1425 | - coverage is just the new ARC set | |
1426 | including self (but with an empty b= in self) | |
1427 | - if non-fail: | |
1428 | - all ARC set headers, set-number order, aar then ams then as, | |
1429 | including self (but with an empty b= in self) | |
1430 | */ | |
1431 | ||
1432 | /* Construct the AS except for the signature */ | |
1433 | ||
a93dbf44 | 1434 | arcset = string_append(NULL, 9, |
617d3932 JH |
1435 | ARC_HDR_AS, |
1436 | US" i=", string_sprintf("%d", instance), | |
1437 | US"; cv=", status, | |
d4772796 | 1438 | US"; a=rsa-sha256; d=", identity, /*XXX hardwired */ |
a93dbf44 JH |
1439 | US"; s=", selector); /*XXX same as AMS */ |
1440 | if (options & ARC_SIGN_OPT_TSTAMP) | |
1441 | arcset = string_append(arcset, 2, | |
0e83c148 | 1442 | US"; t=", string_sprintf("%lu", (u_long)now)); |
a93dbf44 | 1443 | arcset = string_cat(arcset, |
617d3932 JH |
1444 | US";\r\n\t b=;"); |
1445 | ||
1446 | h->slen = arcset->ptr; | |
1447 | h->text = arcset->s; | |
1448 | al->complete = h; | |
1449 | ctx->arcset_chain_last->hdr_as = al; | |
1450 | ||
1451 | /* For any but "fail" chain-verify status, walk the entire chain in order by | |
1452 | instance. For fail, only the new arc-set. Accumulate the elements walked. */ | |
1453 | ||
1454 | for (as = Ustrcmp(status, US"fail") == 0 | |
1455 | ? ctx->arcset_chain_last : ctx->arcset_chain; | |
1456 | as; as = as->next) | |
1457 | { | |
1458 | /* Accumulate AAR then AMS then AS. Relaxed canonicalisation | |
1459 | is required per standard. */ | |
1460 | ||
1461 | h = as->hdr_aar->complete; | |
1462 | hdata = string_cat(hdata, pdkim_relax_header_n(h->text, h->slen, TRUE)); | |
1463 | h = as->hdr_ams->complete; | |
1464 | hdata = string_cat(hdata, pdkim_relax_header_n(h->text, h->slen, TRUE)); | |
1465 | h = as->hdr_as->complete; | |
d9604f37 | 1466 | hdata = string_cat(hdata, pdkim_relax_header_n(h->text, h->slen, !!as->next)); |
617d3932 JH |
1467 | } |
1468 | ||
1469 | /* Calculate the signature from the accumulation */ | |
1470 | ||
1471 | if (!arc_sig_from_pseudoheader(hdata, hashtype, privkey, &sig, US"AS")) | |
1472 | return NULL; | |
1473 | ||
1474 | /* Lose the trailing semicolon */ | |
1475 | arcset->ptr--; | |
1476 | arcset = arc_sign_append_sig(arcset, &sig); | |
1477 | DEBUG(D_transport) debug_printf("ARC: AS '%.*s'\n", arcset->ptr - 2, arcset->s); | |
1478 | ||
1479 | /* Finally, append the AMS and AAR to the new AS */ | |
1480 | ||
1481 | return string_catn(arcset, arcset_interim->s, arcset_interim->ptr); | |
1482 | } | |
1483 | ||
1484 | ||
1485 | /**************************************/ | |
1486 | ||
1487 | /* Return pointer to pdkim_bodyhash for given hash method, creating new | |
1488 | method if needed. | |
1489 | */ | |
1490 | ||
1491 | void * | |
1492 | arc_ams_setup_sign_bodyhash(void) | |
1493 | { | |
1494 | int canon_head, canon_body; | |
1495 | ||
1496 | DEBUG(D_transport) debug_printf("ARC: requesting bodyhash\n"); | |
1497 | pdkim_cstring_to_canons(US"relaxed", 7, &canon_head, &canon_body); /*XXX hardwired */ | |
1498 | return pdkim_set_bodyhash(&dkim_sign_ctx, | |
1499 | pdkim_hashname_to_hashtype(US"sha256", 6), /*XXX hardwired */ | |
1500 | canon_body, | |
1501 | -1); | |
1502 | } | |
1503 | ||
1504 | ||
1505 | ||
b3d9ebf5 JH |
1506 | void |
1507 | arc_sign_init(void) | |
1508 | { | |
1509 | memset(&arc_sign_ctx, 0, sizeof(arc_sign_ctx)); | |
1510 | } | |
1511 | ||
1512 | ||
1513 | ||
617d3932 JH |
1514 | /* A "normal" header line, identified by DKIM processing. These arrive before |
1515 | the call to arc_sign(), which carries any newly-created DKIM headers - and | |
1516 | those go textually before the normal ones in the message. | |
1517 | ||
1518 | We have to take the feed from DKIM as, in the transport-filter case, the | |
1519 | headers are not in memory at the time of the call to arc_sign(). | |
1520 | ||
1521 | Take a copy of the header and construct a reverse-order list. | |
1522 | Also parse ARC-chain headers and build the chain struct, retaining pointers | |
1523 | into the copies. | |
1524 | */ | |
1525 | ||
1526 | static const uschar * | |
1527 | arc_header_sign_feed(gstring * g) | |
1528 | { | |
1529 | uschar * s = string_copyn(g->s, g->ptr); | |
1530 | headers_rlist = arc_rlist_entry(headers_rlist, s, g->ptr); | |
1531 | return arc_try_header(&arc_sign_ctx, headers_rlist->h, TRUE); | |
1532 | } | |
1533 | ||
1534 | ||
1535 | ||
1536 | /* ARC signing. Called from the smtp transport, if the arc_sign option is set. | |
1537 | The dkim_exim_sign() function has already been called, so will have hashed the | |
1538 | message body for us so long as we requested a hash previously. | |
1539 | ||
1540 | Arguments: | |
a93dbf44 JH |
1541 | signspec Three-element colon-sep list: identity, selector, privkey. |
1542 | Optional fourth element: comma-sep list of options. | |
617d3932 JH |
1543 | Already expanded |
1544 | sigheaders Any signature headers already generated, eg. by DKIM, or NULL | |
1545 | errstr Error string | |
1546 | ||
1547 | Return value | |
1548 | Set of headers to prepend to the message, including the supplied sigheaders | |
1549 | but not the plainheaders. | |
1550 | */ | |
1551 | ||
1552 | gstring * | |
1553 | arc_sign(const uschar * signspec, gstring * sigheaders, uschar ** errstr) | |
1554 | { | |
a93dbf44 JH |
1555 | const uschar * identity, * selector, * privkey, * opts, * s; |
1556 | unsigned options = 0; | |
617d3932 JH |
1557 | int sep = 0; |
1558 | header_line * headers; | |
1559 | hdr_rlist * rheaders; | |
1560 | blob ar; | |
1561 | int instance; | |
1562 | gstring * g = NULL; | |
1563 | pdkim_bodyhash * b; | |
1564 | ||
0e83c148 JH |
1565 | expire = now = 0; |
1566 | ||
617d3932 JH |
1567 | /* Parse the signing specification */ |
1568 | ||
1569 | identity = string_nextinlist(&signspec, &sep, NULL, 0); | |
1570 | selector = string_nextinlist(&signspec, &sep, NULL, 0); | |
69a82da3 | 1571 | if ( !*identity || !*selector |
617d3932 JH |
1572 | || !(privkey = string_nextinlist(&signspec, &sep, NULL, 0)) || !*privkey) |
1573 | { | |
c3d43245 | 1574 | log_write(0, LOG_MAIN, "ARC: bad signing-specification (%s)", |
9f7d9fa1 | 1575 | !*identity ? "identity" : !*selector ? "selector" : "private-key"); |
c3d43245 | 1576 | return sigheaders ? sigheaders : string_get(0); |
617d3932 JH |
1577 | } |
1578 | if (*privkey == '/' && !(privkey = expand_file_big_buffer(privkey))) | |
c3d43245 | 1579 | return sigheaders ? sigheaders : string_get(0); |
617d3932 | 1580 | |
a93dbf44 JH |
1581 | if ((opts = string_nextinlist(&signspec, &sep, NULL, 0))) |
1582 | { | |
1583 | int osep = ','; | |
1584 | while ((s = string_nextinlist(&opts, &osep, NULL, 0))) | |
1585 | if (Ustrcmp(s, "timestamps") == 0) | |
0e83c148 | 1586 | { |
a93dbf44 | 1587 | options |= ARC_SIGN_OPT_TSTAMP; |
0e83c148 JH |
1588 | if (!now) now = time(NULL); |
1589 | } | |
1590 | else if (Ustrncmp(s, "expire", 6) == 0) | |
1591 | { | |
1592 | options |= ARC_SIGN_OPT_EXPIRE; | |
1593 | if (*(s += 6) == '=') | |
1594 | if (*++s == '+') | |
1595 | { | |
1596 | if (!(expire = (time_t)atoi(++s))) | |
1597 | expire = ARC_SIGN_DEFAULT_EXPIRE_DELTA; | |
1598 | if (!now) now = time(NULL); | |
1599 | expire += now; | |
1600 | } | |
1601 | else | |
1602 | expire = (time_t)atol(s); | |
1603 | else | |
1604 | { | |
1605 | if (!now) now = time(NULL); | |
1606 | expire = now + ARC_SIGN_DEFAULT_EXPIRE_DELTA; | |
1607 | } | |
1608 | } | |
a93dbf44 JH |
1609 | } |
1610 | ||
617d3932 JH |
1611 | DEBUG(D_transport) debug_printf("ARC: sign for %s\n", identity); |
1612 | ||
b3d9ebf5 JH |
1613 | /* Make an rlist of any new DKIM headers, then add the "normals" rlist to it. |
1614 | Then scan the list for an A-R header. */ | |
617d3932 JH |
1615 | |
1616 | string_from_gstring(sigheaders); | |
1617 | if ((rheaders = arc_sign_scan_headers(&arc_sign_ctx, sigheaders))) | |
1618 | { | |
1619 | hdr_rlist ** rp; | |
0c2250d1 JH |
1620 | for (rp = &headers_rlist; *rp; ) rp = &(*rp)->prev; |
1621 | *rp = rheaders; | |
617d3932 | 1622 | } |
b3d9ebf5 | 1623 | |
617d3932 JH |
1624 | /* Finally, build a normal-order headers list */ |
1625 | /*XXX only needed for hunt-the-AR? */ | |
0c2250d1 | 1626 | /*XXX also, we really should be accepting any number of ADMD-matching ARs */ |
b3d9ebf5 JH |
1627 | { |
1628 | header_line * hnext = NULL; | |
0c2250d1 JH |
1629 | for (rheaders = headers_rlist; rheaders; |
1630 | hnext = rheaders->h, rheaders = rheaders->prev) | |
b3d9ebf5 JH |
1631 | rheaders->h->next = hnext; |
1632 | headers = hnext; | |
1633 | } | |
617d3932 JH |
1634 | |
1635 | if (!(arc_sign_find_ar(headers, identity, &ar))) | |
1636 | { | |
c3d43245 | 1637 | log_write(0, LOG_MAIN, "ARC: no Authentication-Results header for signing"); |
617d3932 JH |
1638 | return sigheaders ? sigheaders : string_get(0); |
1639 | } | |
1640 | ||
b3d9ebf5 JH |
1641 | /* We previously built the data-struct for the existing ARC chain, if any, using a headers |
1642 | feed from the DKIM module. Use that to give the instance number for the ARC set we are | |
1643 | about to build. */ | |
1644 | ||
1645 | DEBUG(D_transport) | |
1646 | if (arc_sign_ctx.arcset_chain_last) | |
1647 | debug_printf("ARC: existing chain highest instance: %d\n", | |
1648 | arc_sign_ctx.arcset_chain_last->instance); | |
1649 | else | |
1650 | debug_printf("ARC: no existing chain\n"); | |
1651 | ||
1652 | instance = arc_sign_ctx.arcset_chain_last ? arc_sign_ctx.arcset_chain_last->instance + 1 : 1; | |
1653 | ||
617d3932 JH |
1654 | /* |
1655 | - Generate AAR | |
1656 | - copy the A-R; prepend i= & identity | |
1657 | */ | |
1658 | ||
1659 | g = arc_sign_append_aar(g, &arc_sign_ctx, identity, instance, &ar); | |
1660 | ||
1661 | /* | |
1662 | - Generate AMS | |
1663 | - Looks fairly like a DKIM sig | |
1664 | - Cover all DKIM sig headers as well as the usuals | |
1665 | - ? oversigning? | |
1666 | - Covers the data | |
1667 | - we must have requested a suitable bodyhash previously | |
1668 | */ | |
1669 | ||
1670 | b = arc_ams_setup_sign_bodyhash(); | |
1671 | g = arc_sign_append_ams(g, &arc_sign_ctx, instance, identity, selector, | |
a93dbf44 | 1672 | &b->bh, headers_rlist, privkey, options); |
617d3932 JH |
1673 | |
1674 | /* | |
1675 | - Generate AS | |
1676 | - no body coverage | |
1677 | - no h= tag; implicit coverage | |
1678 | - arc status from A-R | |
1679 | - if fail: | |
1680 | - coverage is just the new ARC set | |
1681 | including self (but with an empty b= in self) | |
1682 | - if non-fail: | |
1683 | - all ARC set headers, set-number order, aar then ams then as, | |
1684 | including self (but with an empty b= in self) | |
1685 | */ | |
1686 | ||
a93dbf44 JH |
1687 | g = arc_sign_prepend_as(g, &arc_sign_ctx, instance, identity, selector, &ar, |
1688 | privkey, options); | |
617d3932 JH |
1689 | |
1690 | /* Finally, append the dkim headers and return the lot. */ | |
1691 | ||
1692 | g = string_catn(g, sigheaders->s, sigheaders->ptr); | |
1693 | (void) string_from_gstring(g); | |
1694 | gstring_reset_unused(g); | |
1695 | return g; | |
1696 | } | |
1697 | ||
1698 | ||
1699 | /******************************************************************************/ | |
1700 | ||
1701 | /* Check to see if the line is an AMS and if so, set up to validate it. | |
1702 | Called from the DKIM input processing. This must be done now as the message | |
1703 | body data is hashed during input. | |
1704 | ||
1705 | We call the DKIM code to request a body-hash; it has the facility already | |
1706 | and the hash parameters might be common with other requests. | |
1707 | */ | |
1708 | ||
1709 | static const uschar * | |
1710 | arc_header_vfy_feed(gstring * g) | |
1711 | { | |
1712 | header_line h; | |
1713 | arc_line al; | |
1714 | pdkim_bodyhash * b; | |
1715 | uschar * errstr; | |
1716 | ||
1717 | if (!dkim_verify_ctx) return US"no dkim context"; | |
1718 | ||
1719 | if (strncmpic(ARC_HDR_AMS, g->s, ARC_HDRLEN_AMS) != 0) return US"not AMS"; | |
1720 | ||
1721 | DEBUG(D_receive) debug_printf("ARC: spotted AMS header\n"); | |
1722 | /* Parse the AMS header */ | |
1723 | ||
1724 | h.next = NULL; | |
1725 | h.slen = g->size; | |
1726 | h.text = g->s; | |
1727 | memset(&al, 0, sizeof(arc_line)); | |
1728 | if ((errstr = arc_parse_line(&al, &h, ARC_HDRLEN_AMS, FALSE))) | |
1729 | { | |
1730 | DEBUG(D_acl) if (errstr) debug_printf("ARC: %s\n", errstr); | |
1731 | return US"line parsing error"; | |
1732 | } | |
1733 | ||
1734 | /* defaults */ | |
1735 | if (!al.c.data) | |
1736 | { | |
1737 | al.c_body.data = US"simple"; al.c_body.len = 6; | |
1738 | al.c_head = al.c_body; | |
1739 | } | |
1740 | ||
1741 | /* Ask the dkim code to calc a bodyhash with those specs */ | |
1742 | ||
1743 | if (!(b = arc_ams_setup_vfy_bodyhash(&al))) | |
1744 | return US"dkim hash setup fail"; | |
1745 | ||
1746 | /* Discard the reference; search again at verify time, knowing that one | |
1747 | should have been created here. */ | |
1748 | ||
1749 | return NULL; | |
1750 | } | |
1751 | ||
1752 | ||
1753 | ||
1754 | /* A header line has been identified by DKIM processing. | |
1755 | ||
1756 | Arguments: | |
1757 | g Header line | |
1758 | is_vfy TRUE for verify mode or FALSE for signing mode | |
1759 | ||
1760 | Return: | |
1761 | NULL for success, or an error string (probably unused) | |
1762 | */ | |
1763 | ||
1764 | const uschar * | |
1765 | arc_header_feed(gstring * g, BOOL is_vfy) | |
1766 | { | |
1767 | return is_vfy ? arc_header_vfy_feed(g) : arc_header_sign_feed(g); | |
1768 | } | |
1769 | ||
1770 | ||
1771 | ||
1772 | /******************************************************************************/ | |
1773 | ||
1774 | /* Construct an Authenticate-Results header portion, for the ARC module */ | |
1775 | ||
1776 | gstring * | |
1777 | authres_arc(gstring * g) | |
1778 | { | |
1779 | if (arc_state) | |
1780 | { | |
1781 | arc_line * highest_ams; | |
978e78de | 1782 | int start = 0; /* Compiler quietening */ |
617d3932 JH |
1783 | DEBUG(D_acl) start = g->ptr; |
1784 | ||
1785 | g = string_append(g, 2, US";\n\tarc=", arc_state); | |
1786 | if (arc_received_instance > 0) | |
1787 | { | |
1788 | g = string_append(g, 3, US" (i=", | |
93c931f8 JH |
1789 | string_sprintf("%d", arc_received_instance), US")"); |
1790 | if (arc_state_reason) | |
1791 | g = string_append(g, 3, US"(", arc_state_reason, US")"); | |
1792 | g = string_catn(g, US" header.s=", 10); | |
617d3932 JH |
1793 | highest_ams = arc_received->hdr_ams; |
1794 | g = string_catn(g, highest_ams->s.data, highest_ams->s.len); | |
1795 | ||
1796 | g = string_append(g, 2, | |
1797 | US" arc.oldest-pass=", string_sprintf("%d", arc_oldest_pass)); | |
1798 | ||
1799 | if (sender_host_address) | |
1800 | g = string_append(g, 2, US" smtp.client-ip=", sender_host_address); | |
1801 | } | |
b3d9ebf5 JH |
1802 | else if (arc_state_reason) |
1803 | g = string_append(g, 3, US" (", arc_state_reason, US")"); | |
617d3932 JH |
1804 | DEBUG(D_acl) debug_printf("ARC: authres '%.*s'\n", |
1805 | g->ptr - start - 3, g->s + start + 3); | |
1806 | } | |
1807 | else | |
1808 | DEBUG(D_acl) debug_printf("ARC: no authres\n"); | |
1809 | return g; | |
1810 | } | |
1811 | ||
1812 | ||
1813 | # endif /* SUPPORT_SPF */ | |
1814 | #endif /* EXPERIMENTAL_ARC */ | |
1815 | /* vi: aw ai sw=2 | |
1816 | */ |