projects / exim.git / blob
? search:


c4bdb5a931b9b71af20dad4605630d1f09b3fdc6
[exim.git] / src / src / pdkim / pdkim.c
1 /*
2 * PDKIM - a RFC4871 (DKIM) implementation
3 *
4 * Copyright (C) 2009 - 2016 Tom Kistner <tom@duncanthrax.net>
5 * Copyright (C) 2016 Jeremy Harris <jgh@exim.org>
6 *
7 * http://duncanthrax.net/pdkim/
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 *
19 * You should have received a copy of the GNU General Public License along
20 * with this program; if not, write to the Free Software Foundation, Inc.,
21 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
22 */
23
24 #include "../exim.h"
25
26
27 #ifndef DISABLE_DKIM /* entire file */
28
29 #ifndef SUPPORT_TLS
30 # error Need SUPPORT_TLS for DKIM
31 #endif
32
33 #include "crypt_ver.h"
34
35 #ifdef RSA_OPENSSL
36 # include <openssl/rsa.h>
37 # include <openssl/ssl.h>
38 # include <openssl/err.h>
39 #elif defined(RSA_GNUTLS)
40 # include <gnutls/gnutls.h>
41 # include <gnutls/x509.h>
42 #endif
43
44 #include "pdkim.h"
45 #include "rsa.h"
46
47 #define PDKIM_SIGNATURE_VERSION "1"
48 #define PDKIM_PUB_RECORD_VERSION US "DKIM1"
49
50 #define PDKIM_MAX_HEADER_LEN 65536
51 #define PDKIM_MAX_HEADERS 512
52 #define PDKIM_MAX_BODY_LINE_LEN 16384
53 #define PDKIM_DNS_TXT_MAX_NAMELEN 1024
54 #define PDKIM_DEFAULT_SIGN_HEADERS "From:Sender:Reply-To:Subject:Date:"\
55 "Message-ID:To:Cc:MIME-Version:Content-Type:"\
56 "Content-Transfer-Encoding:Content-ID:"\
57 "Content-Description:Resent-Date:Resent-From:"\
58 "Resent-Sender:Resent-To:Resent-Cc:"\
59 "Resent-Message-ID:In-Reply-To:References:"\
60 "List-Id:List-Help:List-Unsubscribe:"\
61 "List-Subscribe:List-Post:List-Owner:List-Archive"
62
63 /* -------------------------------------------------------------------------- */
64 struct pdkim_stringlist {
65 uschar * value;
66 int tag;
67 void * next;
68 };
69
70 /* -------------------------------------------------------------------------- */
71 /* A bunch of list constants */
72 const uschar * pdkim_querymethods[] = {
73 US"dns/txt",
74 NULL
75 };
76 const uschar * pdkim_algos[] = {
77 US"rsa-sha256",
78 US"rsa-sha1",
79 NULL
80 };
81 const uschar * pdkim_canons[] = {
82 US"simple",
83 US"relaxed",
84 NULL
85 };
86 const uschar * pdkim_hashes[] = {
87 US"sha256",
88 US"sha1",
89 NULL
90 };
91 const uschar * pdkim_keytypes[] = {
92 US"rsa",
93 NULL
94 };
95
96 typedef struct pdkim_combined_canon_entry {
97 const uschar * str;
98 int canon_headers;
99 int canon_body;
100 } pdkim_combined_canon_entry;
101
102 pdkim_combined_canon_entry pdkim_combined_canons[] = {
103 { US"simple/simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE },
104 { US"simple/relaxed", PDKIM_CANON_SIMPLE, PDKIM_CANON_RELAXED },
105 { US"relaxed/simple", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE },
106 { US"relaxed/relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_RELAXED },
107 { US"simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE },
108 { US"relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE },
109 { NULL, 0, 0 }
110 };
111
112
113 /* -------------------------------------------------------------------------- */
114
115 const char *
116 pdkim_verify_status_str(int status)
117 {
118 switch(status)
119 {
120 case PDKIM_VERIFY_NONE: return "PDKIM_VERIFY_NONE";
121 case PDKIM_VERIFY_INVALID: return "PDKIM_VERIFY_INVALID";
122 case PDKIM_VERIFY_FAIL: return "PDKIM_VERIFY_FAIL";
123 case PDKIM_VERIFY_PASS: return "PDKIM_VERIFY_PASS";
124 default: return "PDKIM_VERIFY_UNKNOWN";
125 }
126 }
127
128 const char *
129 pdkim_verify_ext_status_str(int ext_status)
130 {
131 switch(ext_status)
132 {
133 case PDKIM_VERIFY_FAIL_BODY: return "PDKIM_VERIFY_FAIL_BODY";
134 case PDKIM_VERIFY_FAIL_MESSAGE: return "PDKIM_VERIFY_FAIL_MESSAGE";
135 case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: return "PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE";
136 case PDKIM_VERIFY_INVALID_BUFFER_SIZE: return "PDKIM_VERIFY_INVALID_BUFFER_SIZE";
137 case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: return "PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD";
138 case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return "PDKIM_VERIFY_INVALID_PUBKEY_IMPORT";
139 case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: return "PDKIM_VERIFY_INVALID_SIGNATURE_ERROR";
140 case PDKIM_VERIFY_INVALID_DKIM_VERSION: return "PDKIM_VERIFY_INVALID_DKIM_VERSION";
141 default: return "PDKIM_VERIFY_UNKNOWN";
142 }
143 }
144
145 const char *
146 pdkim_errstr(int status)
147 {
148 switch(status)
149 {
150 case PDKIM_OK: return "OK";
151 case PDKIM_FAIL: return "FAIL";
152 case PDKIM_ERR_RSA_PRIVKEY: return "RSA_PRIVKEY";
153 case PDKIM_ERR_RSA_SIGNING: return "RSA SIGNING";
154 case PDKIM_ERR_LONG_LINE: return "RSA_LONG_LINE";
155 case PDKIM_ERR_BUFFER_TOO_SMALL: return "BUFFER_TOO_SMALL";
156 case PDKIM_SIGN_PRIVKEY_WRAP: return "PRIVKEY_WRAP";
157 case PDKIM_SIGN_PRIVKEY_B64D: return "PRIVKEY_B64D";
158 default: return "(unknown)";
159 }
160 }
161
162
163 /* -------------------------------------------------------------------------- */
164 /* Print debugging functions */
165 static void
166 pdkim_quoteprint(const uschar *data, int len)
167 {
168 int i;
169 for (i = 0; i < len; i++)
170 {
171 const int c = data[i];
172 switch (c)
173 {
174 case ' ' : debug_printf("{SP}"); break;
175 case '\t': debug_printf("{TB}"); break;
176 case '\r': debug_printf("{CR}"); break;
177 case '\n': debug_printf("{LF}"); break;
178 case '{' : debug_printf("{BO}"); break;
179 case '}' : debug_printf("{BC}"); break;
180 default:
181 if ( (c < 32) || (c > 127) )
182 debug_printf("{%02x}", c);
183 else
184 debug_printf("%c", c);
185 break;
186 }
187 }
188 debug_printf("\n");
189 }
190
191 static void
192 pdkim_hexprint(const uschar *data, int len)
193 {
194 int i;
195 for (i = 0 ; i < len; i++) debug_printf("%02x", data[i]);
196 debug_printf("\n");
197 }
198
199
200
201 static pdkim_stringlist *
202 pdkim_prepend_stringlist(pdkim_stringlist * base, const uschar * str)
203 {
204 pdkim_stringlist * new_entry = store_get(sizeof(pdkim_stringlist));
205
206 memset(new_entry, 0, sizeof(pdkim_stringlist));
207 new_entry->value = string_copy(str);
208 if (base) new_entry->next = base;
209 return new_entry;
210 }
211
212
213
214 /* Trim whitespace fore & aft */
215
216 static void
217 pdkim_strtrim(uschar * str)
218 {
219 uschar * p = str;
220 uschar * q = str;
221 while (*p == '\t' || *p == ' ') p++; /* skip whitespace */
222 while (*p) {*q = *p; q++; p++;} /* dump the leading whitespace */
223 *q = '\0';
224 while (q != str && ( (*q == '\0') || (*q == '\t') || (*q == ' ') ) )
225 { /* dump trailing whitespace */
226 *q = '\0';
227 q--;
228 }
229 }
230
231
232
233 /* -------------------------------------------------------------------------- */
234
235 DLLEXPORT void
236 pdkim_free_ctx(pdkim_ctx *ctx)
237 {
238 }
239
240
241 /* -------------------------------------------------------------------------- */
242 /* Matches the name of the passed raw "header" against
243 the passed colon-separated "tick", and invalidates
244 the entry in tick. Returns OK or fail-code */
245 /*XXX might be safer done using a pdkim_stringlist for "tick" */
246
247 static int
248 header_name_match(const uschar * header, uschar * tick)
249 {
250 uschar * hname;
251 uschar * lcopy;
252 uschar * p;
253 uschar * q;
254 uschar * hcolon = Ustrchr(header, ':'); /* Get header name */
255
256 if (!hcolon)
257 return PDKIM_FAIL; /* This isn't a header */
258
259 /* if we had strncmpic() we wouldn't need this copy */
260 hname = string_copyn(header, hcolon-header);
261
262 /* Copy tick-off list locally, so we can punch zeroes into it */
263 p = lcopy = string_copy(tick);
264
265 for (q = Ustrchr(p, ':'); q; q = Ustrchr(p, ':'))
266 {
267 *q = '\0';
268 if (strcmpic(p, hname) == 0)
269 goto found;
270
271 p = q+1;
272 }
273
274 if (strcmpic(p, hname) == 0)
275 goto found;
276
277 return PDKIM_FAIL;
278
279 found:
280 /* Invalidate header name instance in tick-off list */
281 tick[p-lcopy] = '_';
282 return PDKIM_OK;
283 }
284
285
286 /* -------------------------------------------------------------------------- */
287 /* Performs "relaxed" canonicalization of a header. */
288
289 static uschar *
290 pdkim_relax_header(const uschar * header, int crlf)
291 {
292 BOOL past_field_name = FALSE;
293 BOOL seen_wsp = FALSE;
294 const uschar * p;
295 uschar * relaxed = store_get(Ustrlen(header)+3);
296 uschar * q = relaxed;
297
298 for (p = header; *p; p++)
299 {
300 uschar c = *p;
301 /* Ignore CR & LF */
302 if (c == '\r' || c == '\n')
303 continue;
304 if (c == '\t' || c == ' ')
305 {
306 if (seen_wsp)
307 continue;
308 c = ' '; /* Turns WSP into SP */
309 seen_wsp = TRUE;
310 }
311 else
312 if (!past_field_name && c == ':')
313 {
314 if (seen_wsp) q--; /* This removes WSP before the colon */
315 seen_wsp = TRUE; /* This removes WSP after the colon */
316 past_field_name = TRUE;
317 }
318 else
319 seen_wsp = FALSE;
320
321 /* Lowercase header name */
322 if (!past_field_name) c = tolower(c);
323 *q++ = c;
324 }
325
326 if (q > relaxed && q[-1] == ' ') q--; /* Squash eventual trailing SP */
327
328 if (crlf) { *q++ = '\r'; *q++ = '\n'; }
329 *q = '\0';
330 return relaxed;
331 }
332
333
334 /* -------------------------------------------------------------------------- */
335 #define PDKIM_QP_ERROR_DECODE -1
336
337 static uschar *
338 pdkim_decode_qp_char(uschar *qp_p, int *c)
339 {
340 uschar *initial_pos = qp_p;
341
342 /* Advance one char */
343 qp_p++;
344
345 /* Check for two hex digits and decode them */
346 if (isxdigit(*qp_p) && isxdigit(qp_p[1]))
347 {
348 /* Do hex conversion */
349 *c = (isdigit(*qp_p) ? *qp_p - '0' : toupper(*qp_p) - 'A' + 10) << 4;
350 *c |= isdigit(qp_p[1]) ? qp_p[1] - '0' : toupper(qp_p[1]) - 'A' + 10;
351 return qp_p + 2;
352 }
353
354 /* Illegal char here */
355 *c = PDKIM_QP_ERROR_DECODE;
356 return initial_pos;
357 }
358
359
360 /* -------------------------------------------------------------------------- */
361
362 static uschar *
363 pdkim_decode_qp(uschar * str)
364 {
365 int nchar = 0;
366 uschar * q;
367 uschar * p = str;
368 uschar * n = store_get(Ustrlen(str)+1);
369
370 *n = '\0';
371 q = n;
372 while (*p)
373 {
374 if (*p == '=')
375 {
376 p = pdkim_decode_qp_char(p, &nchar);
377 if (nchar >= 0)
378 {
379 *q++ = nchar;
380 continue;
381 }
382 }
383 else
384 *q++ = *p;
385 p++;
386 }
387 *q = '\0';
388 return n;
389 }
390
391
392 /* -------------------------------------------------------------------------- */
393
394 static void
395 pdkim_decode_base64(uschar *str, blob * b)
396 {
397 int dlen;
398 dlen = b64decode(str, &b->data);
399 if (dlen < 0) b->data = NULL;
400 b->len = dlen;
401 }
402
403 static uschar *
404 pdkim_encode_base64(blob * b)
405 {
406 return b64encode(b->data, b->len);
407 }
408
409
410 /* -------------------------------------------------------------------------- */
411 #define PDKIM_HDR_LIMBO 0
412 #define PDKIM_HDR_TAG 1
413 #define PDKIM_HDR_VALUE 2
414
415 static pdkim_signature *
416 pdkim_parse_sig_header(pdkim_ctx *ctx, uschar * raw_hdr)
417 {
418 pdkim_signature *sig ;
419 uschar *p, *q;
420 uschar * cur_tag = NULL; int ts = 0, tl = 0;
421 uschar * cur_val = NULL; int vs = 0, vl = 0;
422 BOOL past_hname = FALSE;
423 BOOL in_b_val = FALSE;
424 int where = PDKIM_HDR_LIMBO;
425 int i;
426
427 sig = store_get(sizeof(pdkim_signature));
428 memset(sig, 0, sizeof(pdkim_signature));
429 sig->bodylength = -1;
430
431 /* Set so invalid/missing data error display is accurate */
432 sig->algo = -1;
433 sig->version = 0;
434
435 q = sig->rawsig_no_b_val = store_get(Ustrlen(raw_hdr)+1);
436
437 for (p = raw_hdr; ; p++)
438 {
439 char c = *p;
440
441 /* Ignore FWS */
442 if (c == '\r' || c == '\n')
443 goto NEXT_CHAR;
444
445 /* Fast-forward through header name */
446 if (!past_hname)
447 {
448 if (c == ':') past_hname = TRUE;
449 goto NEXT_CHAR;
450 }
451
452 if (where == PDKIM_HDR_LIMBO)
453 {
454 /* In limbo, just wait for a tag-char to appear */
455 if (!(c >= 'a' && c <= 'z'))
456 goto NEXT_CHAR;
457
458 where = PDKIM_HDR_TAG;
459 }
460
461 if (where == PDKIM_HDR_TAG)
462 {
463 if (c >= 'a' && c <= 'z')
464 cur_tag = string_catn(cur_tag, &ts, &tl, p, 1);
465
466 if (c == '=')
467 {
468 cur_tag[tl] = '\0';
469 if (Ustrcmp(cur_tag, "b") == 0)
470 {
471 *q++ = '=';
472 in_b_val = TRUE;
473 }
474 where = PDKIM_HDR_VALUE;
475 goto NEXT_CHAR;
476 }
477 }
478
479 if (where == PDKIM_HDR_VALUE)
480 {
481 if (c == '\r' || c == '\n' || c == ' ' || c == '\t')
482 goto NEXT_CHAR;
483
484 if (c == ';' || c == '\0')
485 {
486 if (tl && vl)
487 {
488 cur_val[vl] = '\0';
489 pdkim_strtrim(cur_val);
490
491 DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag, cur_val);
492
493 switch (*cur_tag)
494 {
495 case 'b':
496 if (cur_tag[1] == 'h')
497 pdkim_decode_base64(cur_val, &sig->bodyhash);
498 else
499 pdkim_decode_base64(cur_val, &sig->sigdata);
500 break;
501 case 'v':
502 /* We only support version 1, and that is currently the
503 only version there is. */
504 sig->version =
505 Ustrcmp(cur_val, PDKIM_SIGNATURE_VERSION) == 0 ? 1 : -1;
506 break;
507 case 'a':
508 for (i = 0; pdkim_algos[i]; i++)
509 if (Ustrcmp(cur_val, pdkim_algos[i]) == 0)
510 {
511 sig->algo = i;
512 break;
513 }
514 break;
515 case 'c':
516 for (i = 0; pdkim_combined_canons[i].str; i++)
517 if (Ustrcmp(cur_val, pdkim_combined_canons[i].str) == 0)
518 {
519 sig->canon_headers = pdkim_combined_canons[i].canon_headers;
520 sig->canon_body = pdkim_combined_canons[i].canon_body;
521 break;
522 }
523 break;
524 case 'q':
525 for (i = 0; pdkim_querymethods[i]; i++)
526 if (Ustrcmp(cur_val, pdkim_querymethods[i]) == 0)
527 {
528 sig->querymethod = i;
529 break;
530 }
531 break;
532 case 's':
533 sig->selector = string_copy(cur_val); break;
534 case 'd':
535 sig->domain = string_copy(cur_val); break;
536 case 'i':
537 sig->identity = pdkim_decode_qp(cur_val); break;
538 case 't':
539 sig->created = strtoul(CS cur_val, NULL, 10); break;
540 case 'x':
541 sig->expires = strtoul(CS cur_val, NULL, 10); break;
542 case 'l':
543 sig->bodylength = strtol(CS cur_val, NULL, 10); break;
544 case 'h':
545 sig->headernames = string_copy(cur_val); break;
546 case 'z':
547 sig->copiedheaders = pdkim_decode_qp(cur_val); break;
548 default:
549 DEBUG(D_acl) debug_printf(" Unknown tag encountered\n");
550 break;
551 }
552 }
553 tl = 0;
554 vl = 0;
555 in_b_val = FALSE;
556 where = PDKIM_HDR_LIMBO;
557 }
558 else
559 cur_val = string_catn(cur_val, &vs, &vl, p, 1);
560 }
561
562 NEXT_CHAR:
563 if (c == '\0')
564 break;
565
566 if (!in_b_val)
567 *q++ = c;
568 }
569
570 *q = '\0';
571 /* Chomp raw header. The final newline must not be added to the signature. */
572 while (--q > sig->rawsig_no_b_val && (*q == '\r' || *q == '\n'))
573 *q = '\0';
574
575 DEBUG(D_acl)
576 {
577 debug_printf(
578 "PDKIM >> Raw signature w/o b= tag value >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
579 pdkim_quoteprint(US sig->rawsig_no_b_val, Ustrlen(sig->rawsig_no_b_val));
580 debug_printf(
581 "PDKIM >> Sig size: %4u bits\n", (unsigned) sig->sigdata.len*8);
582 debug_printf(
583 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
584 }
585
586 exim_sha_init(&sig->body_hash, sig->algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256);
587 return sig;
588 }
589
590
591 /* -------------------------------------------------------------------------- */
592
593 static pdkim_pubkey *
594 pdkim_parse_pubkey_record(pdkim_ctx *ctx, const uschar *raw_record)
595 {
596 pdkim_pubkey *pub;
597 const uschar *p;
598 uschar * cur_tag = NULL; int ts = 0, tl = 0;
599 uschar * cur_val = NULL; int vs = 0, vl = 0;
600 int where = PDKIM_HDR_LIMBO;
601
602 pub = store_get(sizeof(pdkim_pubkey));
603 memset(pub, 0, sizeof(pdkim_pubkey));
604
605 for (p = raw_record; ; p++)
606 {
607 uschar c = *p;
608
609 /* Ignore FWS */
610 if (c != '\r' && c != '\n') switch (where)
611 {
612 case PDKIM_HDR_LIMBO: /* In limbo, just wait for a tag-char to appear */
613 if (!(c >= 'a' && c <= 'z'))
614 break;
615 where = PDKIM_HDR_TAG;
616 /*FALLTHROUGH*/
617
618 case PDKIM_HDR_TAG:
619 if (c >= 'a' && c <= 'z')
620 cur_tag = string_catn(cur_tag, &ts, &tl, p, 1);
621
622 if (c == '=')
623 {
624 cur_tag[tl] = '\0';
625 where = PDKIM_HDR_VALUE;
626 }
627 break;
628
629 case PDKIM_HDR_VALUE:
630 if (c == ';' || c == '\0')
631 {
632 if (tl && vl)
633 {
634 cur_val[vl] = '\0';
635 pdkim_strtrim(cur_val);
636 DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag, cur_val);
637
638 switch (cur_tag[0])
639 {
640 case 'v':
641 pub->version = string_copy(cur_val); break;
642 case 'h':
643 case 'k':
644 /* This field appears to never be used. Also, unclear why
645 a 'k' (key-type_ would go in this field name. There is a field
646 "keytype", also never used.
647 pub->hashes = string_copy(cur_val);
648 */
649 break;
650 case 'g':
651 pub->granularity = string_copy(cur_val); break;
652 case 'n':
653 pub->notes = pdkim_decode_qp(cur_val); break;
654 case 'p':
655 pdkim_decode_base64(US cur_val, &pub->key); break;
656 case 's':
657 pub->srvtype = string_copy(cur_val); break;
658 case 't':
659 if (Ustrchr(cur_val, 'y') != NULL) pub->testing = 1;
660 if (Ustrchr(cur_val, 's') != NULL) pub->no_subdomaining = 1;
661 break;
662 default:
663 DEBUG(D_acl) debug_printf(" Unknown tag encountered\n");
664 break;
665 }
666 }
667 tl = 0;
668 vl = 0;
669 where = PDKIM_HDR_LIMBO;
670 }
671 else
672 cur_val = string_catn(cur_val, &vs, &vl, p, 1);
673 break;
674 }
675
676 if (c == '\0') break;
677 }
678
679 /* Set fallback defaults */
680 if (!pub->version ) pub->version = string_copy(PDKIM_PUB_RECORD_VERSION);
681 else if (Ustrcmp(pub->version, PDKIM_PUB_RECORD_VERSION) != 0) return NULL;
682
683 if (!pub->granularity) pub->granularity = string_copy(US"*");
684 /*
685 if (!pub->keytype ) pub->keytype = string_copy(US"rsa");
686 */
687 if (!pub->srvtype ) pub->srvtype = string_copy(US"*");
688
689 /* p= is required */
690 if (pub->key.data)
691 return pub;
692
693 return NULL;
694 }
695
696
697 /* -------------------------------------------------------------------------- */
698
699 static int
700 pdkim_update_bodyhash(pdkim_ctx *ctx, const char *data, int len)
701 {
702 pdkim_signature *sig = ctx->sig;
703 /* Cache relaxed version of data */
704 uschar *relaxed_data = NULL;
705 int relaxed_len = 0;
706
707 /* Traverse all signatures, updating their hashes. */
708 while (sig)
709 {
710 /* Defaults to simple canon (no further treatment necessary) */
711 const uschar *canon_data = CUS data;
712 int canon_len = len;
713
714 if (sig->canon_body == PDKIM_CANON_RELAXED)
715 {
716 /* Relax the line if not done already */
717 if (!relaxed_data)
718 {
719 BOOL seen_wsp = FALSE;
720 const char *p;
721 int q = 0;
722
723 /* We want to be able to free this else we allocate
724 for the entire message which could be many MB. Since
725 we don't know what allocations the SHA routines might
726 do, not safe to use store_get()/store_reset(). */
727
728 relaxed_data = store_malloc(len+1);
729
730 for (p = data; *p; p++)
731 {
732 char c = *p;
733 if (c == '\r')
734 {
735 if (q > 0 && relaxed_data[q-1] == ' ')
736 q--;
737 }
738 else if (c == '\t' || c == ' ')
739 {
740 c = ' '; /* Turns WSP into SP */
741 if (seen_wsp)
742 continue;
743 seen_wsp = TRUE;
744 }
745 else
746 seen_wsp = FALSE;
747 relaxed_data[q++] = c;
748 }
749 relaxed_data[q] = '\0';
750 relaxed_len = q;
751 }
752 canon_data = relaxed_data;
753 canon_len = relaxed_len;
754 }
755
756 /* Make sure we don't exceed the to-be-signed body length */
757 if ( sig->bodylength >= 0
758 && sig->signed_body_bytes + (unsigned long)canon_len > sig->bodylength
759 )
760 canon_len = sig->bodylength - sig->signed_body_bytes;
761
762 if (canon_len > 0)
763 {
764 exim_sha_update(&sig->body_hash, CUS canon_data, canon_len);
765 sig->signed_body_bytes += canon_len;
766 DEBUG(D_acl) pdkim_quoteprint(canon_data, canon_len);
767 }
768
769 sig = sig->next;
770 }
771
772 if (relaxed_data) store_free(relaxed_data);
773 return PDKIM_OK;
774 }
775
776
777 /* -------------------------------------------------------------------------- */
778
779 static void
780 pdkim_finish_bodyhash(pdkim_ctx *ctx)
781 {
782 pdkim_signature *sig;
783
784 /* Traverse all signatures */
785 for (sig = ctx->sig; sig; sig = sig->next)
786 { /* Finish hashes */
787 blob bh;
788
789 exim_sha_finish(&sig->body_hash, &bh);
790
791 DEBUG(D_acl)
792 {
793 debug_printf("PDKIM [%s] Body bytes hashed: %lu\n"
794 "PDKIM [%s] Body hash computed: ",
795 sig->domain, sig->signed_body_bytes, sig->domain);
796 pdkim_hexprint(CUS bh.data, bh.len);
797 }
798
799 /* SIGNING -------------------------------------------------------------- */
800 if (ctx->flags & PDKIM_MODE_SIGN)
801 {
802 sig->bodyhash = bh;
803
804 /* If bodylength limit is set, and we have received less bytes
805 than the requested amount, effectively remove the limit tag. */
806 if (sig->signed_body_bytes < sig->bodylength)
807 sig->bodylength = -1;
808 }
809
810 /* VERIFICATION --------------------------------------------------------- */
811 else
812 {
813 /* Compare bodyhash */
814 if (memcmp(bh.data, sig->bodyhash.data, bh.len) == 0)
815 {
816 DEBUG(D_acl) debug_printf("PDKIM [%s] Body hash verified OK\n", sig->domain);
817 }
818 else
819 {
820 DEBUG(D_acl)
821 {
822 debug_printf("PDKIM [%s] Body hash signature from headers: ", sig->domain);
823 pdkim_hexprint(sig->bodyhash.data,
824 exim_sha_hashlen(&sig->body_hash));
825 debug_printf("PDKIM [%s] Body hash did NOT verify\n", sig->domain);
826 }
827 sig->verify_status = PDKIM_VERIFY_FAIL;
828 sig->verify_ext_status = PDKIM_VERIFY_FAIL_BODY;
829 }
830 }
831 }
832 }
833
834
835
836 static int
837 pdkim_body_complete(pdkim_ctx * ctx)
838 {
839 pdkim_signature * sig = ctx->sig; /*XXX assumes only one sig */
840
841 /* In simple body mode, if any empty lines were buffered,
842 replace with one. rfc 4871 3.4.3 */
843 /*XXX checking the signed-body-bytes is a gross hack; I think
844 it indicates that all linebreaks should be buffered, including
845 the one terminating a text line */
846
847 if ( sig && sig->canon_body == PDKIM_CANON_SIMPLE
848 && sig->signed_body_bytes == 0
849 && ctx->num_buffered_crlf > 0
850 )
851 pdkim_update_bodyhash(ctx, "\r\n", 2);
852
853 ctx->flags |= PDKIM_SEEN_EOD;
854 ctx->linebuf_offset = 0;
855 return PDKIM_OK;
856 }
857
858
859
860 /* -------------------------------------------------------------------------- */
861 /* Call from pdkim_feed below for processing complete body lines */
862
863 static int
864 pdkim_bodyline_complete(pdkim_ctx *ctx)
865 {
866 char *p = ctx->linebuf;
867 int n = ctx->linebuf_offset;
868 pdkim_signature *sig = ctx->sig; /*XXX assumes only one sig */
869
870 /* Ignore extra data if we've seen the end-of-data marker */
871 if (ctx->flags & PDKIM_SEEN_EOD) goto BAIL;
872
873 /* We've always got one extra byte to stuff a zero ... */
874 ctx->linebuf[ctx->linebuf_offset] = '\0';
875
876 /* Terminate on EOD marker */
877 if (ctx->flags & PDKIM_DOT_TERM)
878 {
879 if ( memcmp(p, ".\r\n", 3) == 0)
880 return pdkim_body_complete(ctx);
881
882 /* Unstuff dots */
883 if (memcmp(p, "..", 2) == 0)
884 {
885 p++;
886 n--;
887 }
888 }
889
890 /* Empty lines need to be buffered until we find a non-empty line */
891 if (memcmp(p, "\r\n", 2) == 0)
892 {
893 ctx->num_buffered_crlf++;
894 goto BAIL;
895 }
896
897 if (sig && sig->canon_body == PDKIM_CANON_RELAXED)
898 {
899 /* Lines with just spaces need to be buffered too */
900 char *check = p;
901 while (memcmp(check, "\r\n", 2) != 0)
902 {
903 char c = *check;
904
905 if (c != '\t' && c != ' ')
906 goto PROCESS;
907 check++;
908 }
909
910 ctx->num_buffered_crlf++;
911 goto BAIL;
912 }
913
914 PROCESS:
915 /* At this point, we have a non-empty line, so release the buffered ones. */
916 while (ctx->num_buffered_crlf)
917 {
918 pdkim_update_bodyhash(ctx, "\r\n", 2);
919 ctx->num_buffered_crlf--;
920 }
921
922 pdkim_update_bodyhash(ctx, p, n);
923
924 BAIL:
925 ctx->linebuf_offset = 0;
926 return PDKIM_OK;
927 }
928
929
930 /* -------------------------------------------------------------------------- */
931 /* Callback from pdkim_feed below for processing complete headers */
932 #define DKIM_SIGNATURE_HEADERNAME "DKIM-Signature:"
933
934 static int
935 pdkim_header_complete(pdkim_ctx *ctx)
936 {
937 /* Special case: The last header can have an extra \r appended */
938 if ( (ctx->cur_header_len > 1) &&
939 (ctx->cur_header[(ctx->cur_header_len)-1] == '\r') )
940 --ctx->cur_header_len;
941 ctx->cur_header[ctx->cur_header_len] = '\0';
942
943 ctx->num_headers++;
944 if (ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL;
945
946 /* SIGNING -------------------------------------------------------------- */
947 if (ctx->flags & PDKIM_MODE_SIGN)
948 {
949 pdkim_signature *sig;
950
951 for (sig = ctx->sig; sig; sig = sig->next) /* Traverse all signatures */
952
953 /* Add header to the signed headers list (in reverse order) */
954 sig->headers = pdkim_prepend_stringlist(sig->headers,
955 ctx->cur_header);
956 }
957
958 /* VERIFICATION ----------------------------------------------------------- */
959 /* DKIM-Signature: headers are added to the verification list */
960 else
961 {
962 if (strncasecmp(CCS ctx->cur_header,
963 DKIM_SIGNATURE_HEADERNAME,
964 Ustrlen(DKIM_SIGNATURE_HEADERNAME)) == 0)
965 {
966 pdkim_signature *new_sig;
967
968 /* Create and chain new signature block */
969 DEBUG(D_acl) debug_printf(
970 "PDKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
971
972 if ((new_sig = pdkim_parse_sig_header(ctx, ctx->cur_header)))
973 {
974 pdkim_signature *last_sig = ctx->sig;
975 if (!last_sig)
976 ctx->sig = new_sig;
977 else
978 {
979 while (last_sig->next) last_sig = last_sig->next;
980 last_sig->next = new_sig;
981 }
982 }
983 else
984 DEBUG(D_acl) debug_printf(
985 "Error while parsing signature header\n"
986 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
987 }
988
989 /* every other header is stored for signature verification */
990 else
991 ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header);
992 }
993
994 BAIL:
995 *ctx->cur_header = '\0';
996 ctx->cur_header_len = 0; /* leave buffer for reuse */
997 return PDKIM_OK;
998 }
999
1000
1001
1002 /* -------------------------------------------------------------------------- */
1003 #define HEADER_BUFFER_FRAG_SIZE 256
1004
1005 DLLEXPORT int
1006 pdkim_feed(pdkim_ctx *ctx, char *data, int len)
1007 {
1008 int p;
1009
1010 /* Alternate EOD signal, used in non-dotstuffing mode */
1011 if (!data)
1012 pdkim_body_complete(ctx);
1013
1014 else for (p = 0; p<len; p++)
1015 {
1016 uschar c = data[p];
1017
1018 if (ctx->flags & PDKIM_PAST_HDRS)
1019 {
1020 /* Processing body byte */
1021 ctx->linebuf[ctx->linebuf_offset++] = c;
1022 if (c == '\n')
1023 {
1024 int rc = pdkim_bodyline_complete(ctx); /* End of line */
1025 if (rc != PDKIM_OK) return rc;
1026 }
1027 if (ctx->linebuf_offset == (PDKIM_MAX_BODY_LINE_LEN-1))
1028 return PDKIM_ERR_LONG_LINE;
1029 }
1030 else
1031 {
1032 /* Processing header byte */
1033 if (c != '\r')
1034 {
1035 if (c == '\n')
1036 {
1037 if (ctx->flags & PDKIM_SEEN_LF)
1038 {
1039 int rc = pdkim_header_complete(ctx); /* Seen last header line */
1040 if (rc != PDKIM_OK) return rc;
1041
1042 ctx->flags = ctx->flags & ~PDKIM_SEEN_LF | PDKIM_PAST_HDRS;
1043 DEBUG(D_acl) debug_printf(
1044 "PDKIM >> Body data for hash, canonicalized >>>>>>>>>>>>>>>>>>>>>>\n");
1045 continue;
1046 }
1047 else
1048 ctx->flags |= PDKIM_SEEN_LF;
1049 }
1050 else if (ctx->flags & PDKIM_SEEN_LF)
1051 {
1052 if (!(c == '\t' || c == ' '))
1053 {
1054 int rc = pdkim_header_complete(ctx); /* End of header */
1055 if (rc != PDKIM_OK) return rc;
1056 }
1057 ctx->flags &= ~PDKIM_SEEN_LF;
1058 }
1059 }
1060
1061 if (ctx->cur_header_len < PDKIM_MAX_HEADER_LEN)
1062 ctx->cur_header = string_catn(ctx->cur_header, &ctx->cur_header_size,
1063 &ctx->cur_header_len, CUS &data[p], 1);
1064 }
1065 }
1066 return PDKIM_OK;
1067 }
1068
1069
1070
1071 /* Extend a grwong header with a continuation-linebreak */
1072 static uschar *
1073 pdkim_hdr_cont(uschar * str, int * size, int * ptr, int * col)
1074 {
1075 *col = 1;
1076 return string_catn(str, size, ptr, US"\r\n\t", 3);
1077 }
1078
1079
1080
1081 /*
1082 * RFC 5322 specifies that header line length SHOULD be no more than 78
1083 * lets make it so!
1084 * pdkim_headcat
1085 *
1086 * returns uschar * (not nul-terminated)
1087 *
1088 * col: this int holds and receives column number (octets since last '\n')
1089 * str: partial string to append to
1090 * size: current buffer size for str
1091 * ptr: current tail-pointer for str
1092 * pad: padding, split line or space after before or after eg: ";"
1093 * intro: - must join to payload eg "h=", usually the tag name
1094 * payload: eg base64 data - long data can be split arbitrarily.
1095 *
1096 * this code doesn't fold the header in some of the places that RFC4871
1097 * allows: As per RFC5322(2.2.3) it only folds before or after tag-value
1098 * pairs and inside long values. it also always spaces or breaks after the
1099 * "pad"
1100 *
1101 * no guarantees are made for output given out-of range input. like tag
1102 * names longer than 78, or bogus col. Input is assumed to be free of line breaks.
1103 */
1104
1105 static uschar *
1106 pdkim_headcat(int * col, uschar * str, int * size, int * ptr,
1107 const uschar * pad, const uschar * intro, const uschar * payload)
1108 {
1109 size_t l;
1110
1111 if (pad)
1112 {
1113 l = Ustrlen(pad);
1114 if (*col + l > 78)
1115 str = pdkim_hdr_cont(str, size, ptr, col);
1116 str = string_catn(str, size, ptr, pad, l);
1117 *col += l;
1118 }
1119
1120 l = (pad?1:0) + (intro?Ustrlen(intro):0);
1121
1122 if (*col + l > 78)
1123 { /*can't fit intro - start a new line to make room.*/
1124 str = pdkim_hdr_cont(str, size, ptr, col);
1125 l = intro?Ustrlen(intro):0;
1126 }
1127
1128 l += payload ? Ustrlen(payload):0 ;
1129
1130 while (l>77)
1131 { /* this fragment will not fit on a single line */
1132 if (pad)
1133 {
1134 str = string_catn(str, size, ptr, US" ", 1);
1135 *col += 1;
1136 pad = NULL; /* only want this once */
1137 l--;
1138 }
1139
1140 if (intro)
1141 {
1142 size_t sl = Ustrlen(intro);
1143
1144 str = string_catn(str, size, ptr, intro, sl);
1145 *col += sl;
1146 l -= sl;
1147 intro = NULL; /* only want this once */
1148 }
1149
1150 if (payload)
1151 {
1152 size_t sl = Ustrlen(payload);
1153 size_t chomp = *col+sl < 77 ? sl : 78-*col;
1154
1155 str = string_catn(str, size, ptr, payload, chomp);
1156 *col += chomp;
1157 payload += chomp;
1158 l -= chomp-1;
1159 }
1160
1161 /* the while precondition tells us it didn't fit. */
1162 str = pdkim_hdr_cont(str, size, ptr, col);
1163 }
1164
1165 if (*col + l > 78)
1166 {
1167 str = pdkim_hdr_cont(str, size, ptr, col);
1168 pad = NULL;
1169 }
1170
1171 if (pad)
1172 {
1173 str = string_catn(str, size, ptr, US" ", 1);
1174 *col += 1;
1175 pad = NULL;
1176 }
1177
1178 if (intro)
1179 {
1180 size_t sl = Ustrlen(intro);
1181
1182 str = string_catn(str, size, ptr, intro, sl);
1183 *col += sl;
1184 l -= sl;
1185 intro = NULL;
1186 }
1187
1188 if (payload)
1189 {
1190 size_t sl = Ustrlen(payload);
1191
1192 str = string_catn(str, size, ptr, payload, sl);
1193 *col += sl;
1194 }
1195
1196 return str;
1197 }
1198
1199
1200 /* -------------------------------------------------------------------------- */
1201
1202 static uschar *
1203 pdkim_create_header(pdkim_signature *sig, BOOL final)
1204 {
1205 uschar * base64_bh;
1206 uschar * base64_b;
1207 int col = 0;
1208 uschar * hdr; int hdr_size = 0, hdr_len = 0;
1209 uschar * canon_all; int can_size = 0, can_len = 0;
1210
1211 canon_all = string_cat (NULL, &can_size, &can_len,
1212 pdkim_canons[sig->canon_headers]);
1213 canon_all = string_catn(canon_all, &can_size, &can_len, US"/", 1);
1214 canon_all = string_cat (canon_all, &can_size, &can_len,
1215 pdkim_canons[sig->canon_body]);
1216 canon_all[can_len] = '\0';
1217
1218 hdr = string_cat(NULL, &hdr_size, &hdr_len,
1219 US"DKIM-Signature: v="PDKIM_SIGNATURE_VERSION);
1220 col = hdr_len;
1221
1222 /* Required and static bits */
1223 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"a=",
1224 pdkim_algos[sig->algo]);
1225 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"q=",
1226 pdkim_querymethods[sig->querymethod]);
1227 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"c=",
1228 canon_all);
1229 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"d=",
1230 sig->domain);
1231 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"s=",
1232 sig->selector);
1233
1234 /* list of header names can be split between items. */
1235 {
1236 uschar * n = string_copy(sig->headernames);
1237 uschar * i = US"h=";
1238 uschar * s = US";";
1239
1240 while (*n)
1241 {
1242 uschar * c = Ustrchr(n, ':');
1243
1244 if (c) *c ='\0';
1245
1246 if (!i)
1247 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, NULL, NULL, US":");
1248
1249 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, s, i, n);
1250
1251 if (!c)
1252 break;
1253
1254 n = c+1;
1255 s = NULL;
1256 i = NULL;
1257 }
1258 }
1259
1260 base64_bh = pdkim_encode_base64(&sig->bodyhash);
1261 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"bh=", base64_bh);
1262
1263 /* Optional bits */
1264 if (sig->identity)
1265 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"i=", sig->identity);
1266
1267 if (sig->created > 0)
1268 {
1269 uschar minibuf[20];
1270
1271 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->created);
1272 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"t=", minibuf);
1273 }
1274
1275 if (sig->expires > 0)
1276 {
1277 uschar minibuf[20];
1278
1279 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->expires);
1280 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"x=", minibuf);
1281 }
1282
1283 if (sig->bodylength >= 0)
1284 {
1285 uschar minibuf[20];
1286
1287 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->bodylength);
1288 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"l=", minibuf);
1289 }
1290
1291 /* Preliminary or final version? */
1292 base64_b = final ? pdkim_encode_base64(&sig->sigdata) : US"";
1293 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"b=", base64_b);
1294
1295 /* add trailing semicolon: I'm not sure if this is actually needed */
1296 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, NULL, US";", US"");
1297
1298 hdr[hdr_len] = '\0';
1299 return hdr;
1300 }
1301
1302
1303 /* -------------------------------------------------------------------------- */
1304
1305 DLLEXPORT int
1306 pdkim_feed_finish(pdkim_ctx *ctx, pdkim_signature **return_signatures)
1307 {
1308 pdkim_signature *sig = ctx->sig;
1309
1310 /* Check if we must still flush a (partial) header. If that is the
1311 case, the message has no body, and we must compute a body hash
1312 out of '<CR><LF>' */
1313 if (ctx->cur_header && ctx->cur_header_len)
1314 {
1315 int rc = pdkim_header_complete(ctx);
1316 if (rc != PDKIM_OK) return rc;
1317 pdkim_update_bodyhash(ctx, "\r\n", 2);
1318 }
1319 else
1320 DEBUG(D_acl) debug_printf(
1321 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1322
1323 /* Build (and/or evaluate) body hash */
1324 pdkim_finish_bodyhash(ctx);
1325
1326 while (sig)
1327 {
1328 BOOL is_sha1 = sig->algo == PDKIM_ALGO_RSA_SHA1;
1329 hctx hhash_ctx;
1330 uschar * sig_hdr = US"";
1331 blob hhash;
1332 blob hdata;
1333 int hdata_alloc = 0;
1334
1335 hdata.data = NULL;
1336 hdata.len = 0;
1337
1338 exim_sha_init(&hhash_ctx, is_sha1 ? HASH_SHA1 : HASH_SHA256);
1339
1340 DEBUG(D_acl) debug_printf(
1341 "PDKIM >> Header data for hash, canonicalized, in sequence >>>>>>>>>>>>>>\n");
1342
1343 /* SIGNING ---------------------------------------------------------------- */
1344 /* When signing, walk through our header list and add them to the hash. As we
1345 go, construct a list of the header's names to use for the h= parameter.
1346 Then append to that list any remaining header names for which there was no
1347 header to sign. */
1348
1349 if (ctx->flags & PDKIM_MODE_SIGN)
1350 {
1351 uschar * headernames = NULL; /* Collected signed header names */
1352 int hs = 0, hl = 0;
1353 pdkim_stringlist *p;
1354 const uschar * l;
1355 uschar * s;
1356 int sep = 0;
1357
1358 for (p = sig->headers; p; p = p->next)
1359 if (header_name_match(p->value, sig->sign_headers) == PDKIM_OK)
1360 {
1361 uschar * rh;
1362 /* Collect header names (Note: colon presence is guaranteed here) */
1363 uschar * q = Ustrchr(p->value, ':');
1364
1365 headernames = string_catn(headernames, &hs, &hl,
1366 p->value, (q - US p->value) + (p->next ? 1 : 0));
1367
1368 rh = sig->canon_headers == PDKIM_CANON_RELAXED
1369 ? pdkim_relax_header(p->value, 1) /* cook header for relaxed canon */
1370 : string_copy(CUS p->value); /* just copy it for simple canon */
1371
1372 /* Feed header to the hash algorithm */
1373 exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
1374
1375 /* Remember headers block for signing (when the library cannot do incremental) */
1376 (void) exim_rsa_data_append(&hdata, &hdata_alloc, rh);
1377
1378 DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
1379 }
1380
1381 l = sig->sign_headers;
1382 while((s = string_nextinlist(&l, &sep, NULL, 0)))
1383 if (*s != '_')
1384 { /*SSS string_append_listele() */
1385 if (hl > 0 && headernames[hl-1] != ':')
1386 headernames = string_catn(headernames, &hs, &hl, US":", 1);
1387
1388 headernames = string_cat(headernames, &hs, &hl, s);
1389 }
1390 headernames[hl] = '\0';
1391
1392 /* Copy headernames to signature struct */
1393 sig->headernames = headernames;
1394
1395 /* Create signature header with b= omitted */
1396 sig_hdr = pdkim_create_header(sig, FALSE);
1397 }
1398
1399 /* VERIFICATION ----------------------------------------------------------- */
1400 /* When verifying, walk through the header name list in the h= parameter and
1401 add the headers to the hash in that order. */
1402 else
1403 {
1404 uschar * p = sig->headernames;
1405 uschar * q;
1406 pdkim_stringlist * hdrs;
1407
1408 if (p)
1409 {
1410 /* clear tags */
1411 for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
1412 hdrs->tag = 0;
1413
1414 p = string_copy(p);
1415 while(1)
1416 {
1417 if ((q = Ustrchr(p, ':')))
1418 *q = '\0';
1419
1420 /*XXX walk the list of headers in same order as received. */
1421 for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
1422 if ( hdrs->tag == 0
1423 && strncasecmp(CCS hdrs->value, CCS p, Ustrlen(p)) == 0
1424 && (hdrs->value)[Ustrlen(p)] == ':'
1425 )
1426 {
1427 /* cook header for relaxed canon, or just copy it for simple */
1428
1429 uschar * rh = sig->canon_headers == PDKIM_CANON_RELAXED
1430 ? pdkim_relax_header(hdrs->value, 1)
1431 : string_copy(CUS hdrs->value);
1432
1433 /* Feed header to the hash algorithm */
1434 exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
1435
1436 DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
1437 hdrs->tag = 1;
1438 break;
1439 }
1440
1441 if (!q) break;
1442 p = q+1;
1443 }
1444
1445 sig_hdr = string_copy(sig->rawsig_no_b_val);
1446 }
1447 }
1448
1449 DEBUG(D_acl) debug_printf(
1450 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1451
1452 /* Relax header if necessary */
1453 if (sig->canon_headers == PDKIM_CANON_RELAXED)
1454 sig_hdr = pdkim_relax_header(sig_hdr, 0);
1455
1456 DEBUG(D_acl)
1457 {
1458 debug_printf(
1459 "PDKIM >> Signed DKIM-Signature header, canonicalized >>>>>>>>>>>>>>>>>\n");
1460 pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr));
1461 debug_printf(
1462 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1463 }
1464
1465 /* Finalize header hash */
1466 exim_sha_update(&hhash_ctx, CUS sig_hdr, Ustrlen(sig_hdr));
1467 exim_sha_finish(&hhash_ctx, &hhash);
1468
1469 DEBUG(D_acl)
1470 {
1471 debug_printf("PDKIM [%s] Header hash computed: ", sig->domain);
1472 pdkim_hexprint(hhash.data, hhash.len);
1473 }
1474
1475 /* Remember headers block for signing (when the library cannot do incremental) */
1476 if (ctx->flags & PDKIM_MODE_SIGN)
1477 (void) exim_rsa_data_append(&hdata, &hdata_alloc, US sig_hdr);
1478
1479 /* SIGNING ---------------------------------------------------------------- */
1480 if (ctx->flags & PDKIM_MODE_SIGN)
1481 {
1482 es_ctx sctx;
1483 const uschar * errstr;
1484
1485 /* Import private key */
1486 if ((errstr = exim_rsa_signing_init(US sig->rsa_privkey, &sctx)))
1487 {
1488 DEBUG(D_acl) debug_printf("signing_init: %s\n", errstr);
1489 return PDKIM_ERR_RSA_PRIVKEY;
1490 }
1491
1492 /* Do signing. With OpenSSL we are signing the hash of headers just
1493 calculated, with GnuTLS we have to sign an entire block of headers
1494 (due to available interfaces) and it recalculates the hash internally. */
1495
1496 #if defined(RSA_OPENSSL) || defined(RSA_GCRYPT)
1497 hdata = hhash;
1498 #endif
1499
1500 if ((errstr = exim_rsa_sign(&sctx, is_sha1, &hdata, &sig->sigdata)))
1501 {
1502 DEBUG(D_acl) debug_printf("signing: %s\n", errstr);
1503 return PDKIM_ERR_RSA_SIGNING;
1504 }
1505
1506 DEBUG(D_acl)
1507 {
1508 debug_printf( "PDKIM [%s] b computed: ", sig->domain);
1509 pdkim_hexprint(sig->sigdata.data, sig->sigdata.len);
1510 }
1511
1512 sig->signature_header = pdkim_create_header(sig, TRUE);
1513 }
1514
1515 /* VERIFICATION ----------------------------------------------------------- */
1516 else
1517 {
1518 ev_ctx vctx;
1519 const uschar * errstr;
1520 pdkim_pubkey * p;
1521
1522 uschar *dns_txt_name, *dns_txt_reply;
1523
1524 /* Make sure we have all required signature tags */
1525 if (!( sig->domain && *sig->domain
1526 && sig->selector && *sig->selector
1527 && sig->headernames && *sig->headernames
1528 && sig->bodyhash.data
1529 && sig->sigdata.data
1530 && sig->algo > -1
1531 && sig->version
1532 ) )
1533 {
1534 sig->verify_status = PDKIM_VERIFY_INVALID;
1535 sig->verify_ext_status = PDKIM_VERIFY_INVALID_SIGNATURE_ERROR;
1536
1537 DEBUG(D_acl) debug_printf(
1538 " Error in DKIM-Signature header: tags missing or invalid\n"
1539 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1540 goto NEXT_VERIFY;
1541 }
1542
1543 /* Make sure sig uses supported DKIM version (only v1) */
1544 if (sig->version != 1)
1545 {
1546 sig->verify_status = PDKIM_VERIFY_INVALID;
1547 sig->verify_ext_status = PDKIM_VERIFY_INVALID_DKIM_VERSION;
1548
1549 DEBUG(D_acl) debug_printf(
1550 " Error in DKIM-Signature header: unsupported DKIM version\n"
1551 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1552 goto NEXT_VERIFY;
1553 }
1554
1555 /* Fetch public key for signing domain, from DNS */
1556
1557 dns_txt_name = string_sprintf("%s._domainkey.%s.",
1558 sig->selector, sig->domain);
1559
1560 dns_txt_reply = store_get(PDKIM_DNS_TXT_MAX_RECLEN);
1561 memset(dns_txt_reply, 0, PDKIM_DNS_TXT_MAX_RECLEN);
1562
1563 if ( ctx->dns_txt_callback(CS dns_txt_name, CS dns_txt_reply) != PDKIM_OK
1564 || dns_txt_reply[0] == '\0')
1565 {
1566 sig->verify_status = PDKIM_VERIFY_INVALID;
1567 sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE;
1568 goto NEXT_VERIFY;
1569 }
1570
1571 DEBUG(D_acl)
1572 {
1573 debug_printf(
1574 "PDKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"
1575 " Raw record: ");
1576 pdkim_quoteprint(CUS dns_txt_reply, Ustrlen(dns_txt_reply));
1577 }
1578
1579 if ( !(p = pdkim_parse_pubkey_record(ctx, CUS dns_txt_reply))
1580 || (Ustrcmp(p->srvtype, "*") != 0 && Ustrcmp(p->srvtype, "email") != 0)
1581 )
1582 {
1583 sig->verify_status = PDKIM_VERIFY_INVALID;
1584 sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD;
1585
1586 DEBUG(D_acl)
1587 {
1588 if (p)
1589 debug_printf(" Invalid public key service type '%s'\n", p->srvtype);
1590 else
1591 debug_printf(" Error while parsing public key record\n");
1592 debug_printf(
1593 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1594 }
1595 goto NEXT_VERIFY;
1596 }
1597 sig->pubkey = p;
1598
1599 DEBUG(D_acl) debug_printf(
1600 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1601
1602 /* Import public key */
1603 if ((errstr = exim_rsa_verify_init(&sig->pubkey->key, &vctx)))
1604 {
1605 DEBUG(D_acl) debug_printf("verify_init: %s\n", errstr);
1606 sig->verify_status = PDKIM_VERIFY_INVALID;
1607 sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_IMPORT;
1608 goto NEXT_VERIFY;
1609 }
1610
1611 /* Check the signature */
1612 if ((errstr = exim_rsa_verify(&vctx, is_sha1, &hhash, &sig->sigdata)))
1613 {
1614 DEBUG(D_acl) debug_printf("headers verify: %s\n", errstr);
1615 sig->verify_status = PDKIM_VERIFY_FAIL;
1616 sig->verify_ext_status = PDKIM_VERIFY_FAIL_MESSAGE;
1617 goto NEXT_VERIFY;
1618 }
1619
1620
1621 /* We have a winner! (if bodydhash was correct earlier) */
1622 if (sig->verify_status == PDKIM_VERIFY_NONE)
1623 sig->verify_status = PDKIM_VERIFY_PASS;
1624
1625 NEXT_VERIFY:
1626
1627 DEBUG(D_acl)
1628 {
1629 debug_printf("PDKIM [%s] signature status: %s",
1630 sig->domain, pdkim_verify_status_str(sig->verify_status));
1631 if (sig->verify_ext_status > 0)
1632 debug_printf(" (%s)\n",
1633 pdkim_verify_ext_status_str(sig->verify_ext_status));
1634 else
1635 debug_printf("\n");
1636 }
1637 }
1638
1639 sig = sig->next;
1640 }
1641
1642 /* If requested, set return pointer to signature(s) */
1643 if (return_signatures)
1644 *return_signatures = ctx->sig;
1645
1646 return PDKIM_OK;
1647 }
1648
1649
1650 /* -------------------------------------------------------------------------- */
1651
1652 DLLEXPORT pdkim_ctx *
1653 pdkim_init_verify(int(*dns_txt_callback)(char *, char *), BOOL dot_stuffing)
1654 {
1655 pdkim_ctx * ctx;
1656
1657 ctx = store_get(sizeof(pdkim_ctx));
1658 memset(ctx, 0, sizeof(pdkim_ctx));
1659
1660 if (dot_stuffing) ctx->flags = PDKIM_DOT_TERM;
1661 ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
1662 ctx->dns_txt_callback = dns_txt_callback;
1663
1664 return ctx;
1665 }
1666
1667
1668 /* -------------------------------------------------------------------------- */
1669
1670 DLLEXPORT pdkim_ctx *
1671 pdkim_init_sign(char *domain, char *selector, char *rsa_privkey, int algo,
1672 BOOL dot_stuffed)
1673 {
1674 pdkim_ctx *ctx;
1675 pdkim_signature *sig;
1676
1677 if (!domain || !selector || !rsa_privkey)
1678 return NULL;
1679
1680 ctx = store_get(sizeof(pdkim_ctx));
1681 memset(ctx, 0, sizeof(pdkim_ctx));
1682
1683 ctx->flags = dot_stuffed ? PDKIM_MODE_SIGN | PDKIM_DOT_TERM : PDKIM_MODE_SIGN;
1684 ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
1685
1686 sig = store_get(sizeof(pdkim_signature));
1687 memset(sig, 0, sizeof(pdkim_signature));
1688
1689 sig->bodylength = -1;
1690 ctx->sig = sig;
1691
1692 sig->domain = string_copy(US domain);
1693 sig->selector = string_copy(US selector);
1694 sig->rsa_privkey = string_copy(US rsa_privkey);
1695 sig->algo = algo;
1696
1697 exim_sha_init(&sig->body_hash, algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256);
1698 return ctx;
1699 }
1700
1701
1702 /* -------------------------------------------------------------------------- */
1703
1704 DLLEXPORT int
1705 pdkim_set_optional(pdkim_ctx *ctx,
1706 char *sign_headers,
1707 char *identity,
1708 int canon_headers,
1709 int canon_body,
1710 long bodylength,
1711 unsigned long created,
1712 unsigned long expires)
1713 {
1714 pdkim_signature * sig = ctx->sig;
1715
1716 if (identity)
1717 sig->identity = string_copy(US identity);
1718
1719 sig->sign_headers = string_copy(sign_headers
1720 ? US sign_headers : US PDKIM_DEFAULT_SIGN_HEADERS);
1721
1722 sig->canon_headers = canon_headers;
1723 sig->canon_body = canon_body;
1724 sig->bodylength = bodylength;
1725 sig->created = created;
1726 sig->expires = expires;
1727
1728 return PDKIM_OK;
1729 }
1730
1731
1732 void
1733 pdkim_init(void)
1734 {
1735 exim_rsa_init();
1736 }
1737
1738
1739
1740 #endif /*DISABLE_DKIM*/
Unnamed repository; edit this file 'description' to name the repository.