2 * PDKIM - a RFC4871 (DKIM) implementation
4 * Copyright (C) 2009 - 2016 Tom Kistner <tom@duncanthrax.net>
5 * Copyright (C) 2016 Jeremy Harris <jgh@exim.org>
7 * http://duncanthrax.net/pdkim/
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.
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.
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.
27 #ifndef DISABLE_DKIM /* entire file */
30 # error Need SUPPORT_TLS for DKIM
33 #include "crypt_ver.h"
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>
47 #define PDKIM_SIGNATURE_VERSION "1"
48 #define PDKIM_PUB_RECORD_VERSION US "DKIM1"
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"
63 /* -------------------------------------------------------------------------- */
64 struct pdkim_stringlist {
70 /* -------------------------------------------------------------------------- */
71 /* A bunch of list constants */
72 const uschar * pdkim_querymethods[] = {
76 const uschar * pdkim_algos[] = {
81 const uschar * pdkim_canons[] = {
86 const uschar * pdkim_hashes[] = {
91 const uschar * pdkim_keytypes[] = {
96 typedef struct pdkim_combined_canon_entry {
100 } pdkim_combined_canon_entry;
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 },
113 /* -------------------------------------------------------------------------- */
116 pdkim_verify_status_str(int status)
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";
129 pdkim_verify_ext_status_str(int ext_status)
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";
146 pdkim_errstr(int status)
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)";
163 /* -------------------------------------------------------------------------- */
164 /* Print debugging functions */
166 pdkim_quoteprint(const uschar *data, int len)
169 for (i = 0; i < len; i++)
171 const int c = data[i];
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;
181 if ( (c < 32) || (c > 127) )
182 debug_printf("{%02x}", c);
184 debug_printf("%c", c);
192 pdkim_hexprint(const uschar *data, int len)
195 for (i = 0 ; i < len; i++) debug_printf("%02x", data[i]);
201 static pdkim_stringlist *
202 pdkim_prepend_stringlist(pdkim_stringlist * base, const uschar * str)
204 pdkim_stringlist * new_entry = store_get(sizeof(pdkim_stringlist));
206 memset(new_entry, 0, sizeof(pdkim_stringlist));
207 new_entry->value = string_copy(str);
208 if (base) new_entry->next = base;
214 /* Trim whitespace fore & aft */
217 pdkim_strtrim(uschar * str)
221 while (*p == '\t' || *p == ' ') p++; /* skip whitespace */
222 while (*p) {*q = *p; q++; p++;} /* dump the leading whitespace */
224 while (q != str && ( (*q == '\0') || (*q == '\t') || (*q == ' ') ) )
225 { /* dump trailing whitespace */
233 /* -------------------------------------------------------------------------- */
236 pdkim_free_ctx(pdkim_ctx *ctx)
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" */
248 header_name_match(const uschar * header, uschar * tick)
254 uschar * hcolon = Ustrchr(header, ':'); /* Get header name */
257 return PDKIM_FAIL; /* This isn't a header */
259 /* if we had strncmpic() we wouldn't need this copy */
260 hname = string_copyn(header, hcolon-header);
262 /* Copy tick-off list locally, so we can punch zeroes into it */
263 p = lcopy = string_copy(tick);
265 for (q = Ustrchr(p, ':'); q; q = Ustrchr(p, ':'))
268 if (strcmpic(p, hname) == 0)
274 if (strcmpic(p, hname) == 0)
280 /* Invalidate header name instance in tick-off list */
286 /* -------------------------------------------------------------------------- */
287 /* Performs "relaxed" canonicalization of a header. */
290 pdkim_relax_header(const uschar * header, int crlf)
292 BOOL past_field_name = FALSE;
293 BOOL seen_wsp = FALSE;
295 uschar * relaxed = store_get(Ustrlen(header)+3);
296 uschar * q = relaxed;
298 for (p = header; *p; p++)
302 if (c == '\r' || c == '\n')
304 if (c == '\t' || c == ' ')
308 c = ' '; /* Turns WSP into SP */
312 if (!past_field_name && c == ':')
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;
321 /* Lowercase header name */
322 if (!past_field_name) c = tolower(c);
326 if (q > relaxed && q[-1] == ' ') q--; /* Squash eventual trailing SP */
328 if (crlf) { *q++ = '\r'; *q++ = '\n'; }
334 /* -------------------------------------------------------------------------- */
335 #define PDKIM_QP_ERROR_DECODE -1
338 pdkim_decode_qp_char(uschar *qp_p, int *c)
340 uschar *initial_pos = qp_p;
342 /* Advance one char */
345 /* Check for two hex digits and decode them */
346 if (isxdigit(*qp_p) && isxdigit(qp_p[1]))
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;
354 /* Illegal char here */
355 *c = PDKIM_QP_ERROR_DECODE;
360 /* -------------------------------------------------------------------------- */
363 pdkim_decode_qp(uschar * str)
368 uschar * n = store_get(Ustrlen(str)+1);
376 p = pdkim_decode_qp_char(p, &nchar);
392 /* -------------------------------------------------------------------------- */
395 pdkim_decode_base64(uschar *str, blob * b)
398 dlen = b64decode(str, &b->data);
399 if (dlen < 0) b->data = NULL;
404 pdkim_encode_base64(blob * b)
406 return b64encode(b->data, b->len);
410 /* -------------------------------------------------------------------------- */
411 #define PDKIM_HDR_LIMBO 0
412 #define PDKIM_HDR_TAG 1
413 #define PDKIM_HDR_VALUE 2
415 static pdkim_signature *
416 pdkim_parse_sig_header(pdkim_ctx *ctx, uschar * raw_hdr)
418 pdkim_signature *sig ;
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;
427 sig = store_get(sizeof(pdkim_signature));
428 memset(sig, 0, sizeof(pdkim_signature));
429 sig->bodylength = -1;
431 /* Set so invalid/missing data error display is accurate */
435 q = sig->rawsig_no_b_val = store_get(Ustrlen(raw_hdr)+1);
437 for (p = raw_hdr; ; p++)
442 if (c == '\r' || c == '\n')
445 /* Fast-forward through header name */
448 if (c == ':') past_hname = TRUE;
452 if (where == PDKIM_HDR_LIMBO)
454 /* In limbo, just wait for a tag-char to appear */
455 if (!(c >= 'a' && c <= 'z'))
458 where = PDKIM_HDR_TAG;
461 if (where == PDKIM_HDR_TAG)
463 if (c >= 'a' && c <= 'z')
464 cur_tag = string_catn(cur_tag, &ts, &tl, p, 1);
469 if (Ustrcmp(cur_tag, "b") == 0)
474 where = PDKIM_HDR_VALUE;
479 if (where == PDKIM_HDR_VALUE)
481 if (c == '\r' || c == '\n' || c == ' ' || c == '\t')
484 if (c == ';' || c == '\0')
489 pdkim_strtrim(cur_val);
491 DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag, cur_val);
496 if (cur_tag[1] == 'h')
497 pdkim_decode_base64(cur_val, &sig->bodyhash);
499 pdkim_decode_base64(cur_val, &sig->sigdata);
502 /* We only support version 1, and that is currently the
503 only version there is. */
505 Ustrcmp(cur_val, PDKIM_SIGNATURE_VERSION) == 0 ? 1 : -1;
508 for (i = 0; pdkim_algos[i]; i++)
509 if (Ustrcmp(cur_val, pdkim_algos[i]) == 0)
516 for (i = 0; pdkim_combined_canons[i].str; i++)
517 if (Ustrcmp(cur_val, pdkim_combined_canons[i].str) == 0)
519 sig->canon_headers = pdkim_combined_canons[i].canon_headers;
520 sig->canon_body = pdkim_combined_canons[i].canon_body;
525 for (i = 0; pdkim_querymethods[i]; i++)
526 if (Ustrcmp(cur_val, pdkim_querymethods[i]) == 0)
528 sig->querymethod = i;
533 sig->selector = string_copy(cur_val); break;
535 sig->domain = string_copy(cur_val); break;
537 sig->identity = pdkim_decode_qp(cur_val); break;
539 sig->created = strtoul(CS cur_val, NULL, 10); break;
541 sig->expires = strtoul(CS cur_val, NULL, 10); break;
543 sig->bodylength = strtol(CS cur_val, NULL, 10); break;
545 sig->headernames = string_copy(cur_val); break;
547 sig->copiedheaders = pdkim_decode_qp(cur_val); break;
549 DEBUG(D_acl) debug_printf(" Unknown tag encountered\n");
556 where = PDKIM_HDR_LIMBO;
559 cur_val = string_catn(cur_val, &vs, &vl, p, 1);
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'))
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));
581 "PDKIM >> Sig size: %4u bits\n", (unsigned) sig->sigdata.len*8);
583 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
586 exim_sha_init(&sig->body_hash, sig->algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256);
591 /* -------------------------------------------------------------------------- */
593 static pdkim_pubkey *
594 pdkim_parse_pubkey_record(pdkim_ctx *ctx, const uschar *raw_record)
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;
602 pub = store_get(sizeof(pdkim_pubkey));
603 memset(pub, 0, sizeof(pdkim_pubkey));
605 for (p = raw_record; ; p++)
610 if (c != '\r' && c != '\n') switch (where)
612 case PDKIM_HDR_LIMBO: /* In limbo, just wait for a tag-char to appear */
613 if (!(c >= 'a' && c <= 'z'))
615 where = PDKIM_HDR_TAG;
619 if (c >= 'a' && c <= 'z')
620 cur_tag = string_catn(cur_tag, &ts, &tl, p, 1);
625 where = PDKIM_HDR_VALUE;
629 case PDKIM_HDR_VALUE:
630 if (c == ';' || c == '\0')
635 pdkim_strtrim(cur_val);
636 DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag, cur_val);
641 pub->version = string_copy(cur_val); break;
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);
651 pub->granularity = string_copy(cur_val); break;
653 pub->notes = pdkim_decode_qp(cur_val); break;
655 pdkim_decode_base64(US cur_val, &pub->key); break;
657 pub->srvtype = string_copy(cur_val); break;
659 if (Ustrchr(cur_val, 'y') != NULL) pub->testing = 1;
660 if (Ustrchr(cur_val, 's') != NULL) pub->no_subdomaining = 1;
663 DEBUG(D_acl) debug_printf(" Unknown tag encountered\n");
669 where = PDKIM_HDR_LIMBO;
672 cur_val = string_catn(cur_val, &vs, &vl, p, 1);
676 if (c == '\0') break;
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;
683 if (!pub->granularity) pub->granularity = string_copy(US"*");
685 if (!pub->keytype ) pub->keytype = string_copy(US"rsa");
687 if (!pub->srvtype ) pub->srvtype = string_copy(US"*");
697 /* -------------------------------------------------------------------------- */
700 pdkim_update_bodyhash(pdkim_ctx *ctx, const char *data, int len)
702 pdkim_signature *sig = ctx->sig;
703 /* Cache relaxed version of data */
704 uschar *relaxed_data = NULL;
707 /* Traverse all signatures, updating their hashes. */
710 /* Defaults to simple canon (no further treatment necessary) */
711 const uschar *canon_data = CUS data;
714 if (sig->canon_body == PDKIM_CANON_RELAXED)
716 /* Relax the line if not done already */
719 BOOL seen_wsp = FALSE;
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(). */
728 relaxed_data = store_malloc(len+1);
730 for (p = data; *p; p++)
735 if (q > 0 && relaxed_data[q-1] == ' ')
738 else if (c == '\t' || c == ' ')
740 c = ' '; /* Turns WSP into SP */
747 relaxed_data[q++] = c;
749 relaxed_data[q] = '\0';
752 canon_data = relaxed_data;
753 canon_len = relaxed_len;
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
760 canon_len = sig->bodylength - sig->signed_body_bytes;
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);
772 if (relaxed_data) store_free(relaxed_data);
777 /* -------------------------------------------------------------------------- */
780 pdkim_finish_bodyhash(pdkim_ctx *ctx)
782 pdkim_signature *sig;
784 /* Traverse all signatures */
785 for (sig = ctx->sig; sig; sig = sig->next)
786 { /* Finish hashes */
789 exim_sha_finish(&sig->body_hash, &bh);
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);
799 /* SIGNING -------------------------------------------------------------- */
800 if (ctx->flags & PDKIM_MODE_SIGN)
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;
810 /* VERIFICATION --------------------------------------------------------- */
813 /* Compare bodyhash */
814 if (memcmp(bh.data, sig->bodyhash.data, bh.len) == 0)
816 DEBUG(D_acl) debug_printf("PDKIM [%s] Body hash verified OK\n", sig->domain);
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);
827 sig->verify_status = PDKIM_VERIFY_FAIL;
828 sig->verify_ext_status = PDKIM_VERIFY_FAIL_BODY;
837 pdkim_body_complete(pdkim_ctx * ctx)
839 pdkim_signature * sig = ctx->sig; /*XXX assumes only one sig */
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 */
847 if ( sig && sig->canon_body == PDKIM_CANON_SIMPLE
848 && sig->signed_body_bytes == 0
849 && ctx->num_buffered_crlf > 0
851 pdkim_update_bodyhash(ctx, "\r\n", 2);
853 ctx->flags |= PDKIM_SEEN_EOD;
854 ctx->linebuf_offset = 0;
860 /* -------------------------------------------------------------------------- */
861 /* Call from pdkim_feed below for processing complete body lines */
864 pdkim_bodyline_complete(pdkim_ctx *ctx)
866 char *p = ctx->linebuf;
867 int n = ctx->linebuf_offset;
868 pdkim_signature *sig = ctx->sig; /*XXX assumes only one sig */
870 /* Ignore extra data if we've seen the end-of-data marker */
871 if (ctx->flags & PDKIM_SEEN_EOD) goto BAIL;
873 /* We've always got one extra byte to stuff a zero ... */
874 ctx->linebuf[ctx->linebuf_offset] = '\0';
876 /* Terminate on EOD marker */
877 if (ctx->flags & PDKIM_DOT_TERM)
879 if ( memcmp(p, ".\r\n", 3) == 0)
880 return pdkim_body_complete(ctx);
883 if (memcmp(p, "..", 2) == 0)
890 /* Empty lines need to be buffered until we find a non-empty line */
891 if (memcmp(p, "\r\n", 2) == 0)
893 ctx->num_buffered_crlf++;
897 if (sig && sig->canon_body == PDKIM_CANON_RELAXED)
899 /* Lines with just spaces need to be buffered too */
901 while (memcmp(check, "\r\n", 2) != 0)
905 if (c != '\t' && c != ' ')
910 ctx->num_buffered_crlf++;
915 /* At this point, we have a non-empty line, so release the buffered ones. */
916 while (ctx->num_buffered_crlf)
918 pdkim_update_bodyhash(ctx, "\r\n", 2);
919 ctx->num_buffered_crlf--;
922 pdkim_update_bodyhash(ctx, p, n);
925 ctx->linebuf_offset = 0;
930 /* -------------------------------------------------------------------------- */
931 /* Callback from pdkim_feed below for processing complete headers */
932 #define DKIM_SIGNATURE_HEADERNAME "DKIM-Signature:"
935 pdkim_header_complete(pdkim_ctx *ctx)
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';
944 if (ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL;
946 /* SIGNING -------------------------------------------------------------- */
947 if (ctx->flags & PDKIM_MODE_SIGN)
949 pdkim_signature *sig;
951 for (sig = ctx->sig; sig; sig = sig->next) /* Traverse all signatures */
953 /* Add header to the signed headers list (in reverse order) */
954 sig->headers = pdkim_prepend_stringlist(sig->headers,
958 /* VERIFICATION ----------------------------------------------------------- */
959 /* DKIM-Signature: headers are added to the verification list */
962 if (strncasecmp(CCS ctx->cur_header,
963 DKIM_SIGNATURE_HEADERNAME,
964 Ustrlen(DKIM_SIGNATURE_HEADERNAME)) == 0)
966 pdkim_signature *new_sig;
968 /* Create and chain new signature block */
969 DEBUG(D_acl) debug_printf(
970 "PDKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n");
972 if ((new_sig = pdkim_parse_sig_header(ctx, ctx->cur_header)))
974 pdkim_signature *last_sig = ctx->sig;
979 while (last_sig->next) last_sig = last_sig->next;
980 last_sig->next = new_sig;
984 DEBUG(D_acl) debug_printf(
985 "Error while parsing signature header\n"
986 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
989 /* every other header is stored for signature verification */
991 ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header);
995 *ctx->cur_header = '\0';
996 ctx->cur_header_len = 0; /* leave buffer for reuse */
1002 /* -------------------------------------------------------------------------- */
1003 #define HEADER_BUFFER_FRAG_SIZE 256
1006 pdkim_feed(pdkim_ctx *ctx, char *data, int len)
1010 /* Alternate EOD signal, used in non-dotstuffing mode */
1012 pdkim_body_complete(ctx);
1014 else for (p = 0; p<len; p++)
1018 if (ctx->flags & PDKIM_PAST_HDRS)
1020 /* Processing body byte */
1021 ctx->linebuf[ctx->linebuf_offset++] = c;
1024 int rc = pdkim_bodyline_complete(ctx); /* End of line */
1025 if (rc != PDKIM_OK) return rc;
1027 if (ctx->linebuf_offset == (PDKIM_MAX_BODY_LINE_LEN-1))
1028 return PDKIM_ERR_LONG_LINE;
1032 /* Processing header byte */
1037 if (ctx->flags & PDKIM_SEEN_LF)
1039 int rc = pdkim_header_complete(ctx); /* Seen last header line */
1040 if (rc != PDKIM_OK) return rc;
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");
1048 ctx->flags |= PDKIM_SEEN_LF;
1050 else if (ctx->flags & PDKIM_SEEN_LF)
1052 if (!(c == '\t' || c == ' '))
1054 int rc = pdkim_header_complete(ctx); /* End of header */
1055 if (rc != PDKIM_OK) return rc;
1057 ctx->flags &= ~PDKIM_SEEN_LF;
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);
1071 /* Extend a grwong header with a continuation-linebreak */
1073 pdkim_hdr_cont(uschar * str, int * size, int * ptr, int * col)
1076 return string_catn(str, size, ptr, US"\r\n\t", 3);
1082 * RFC 5322 specifies that header line length SHOULD be no more than 78
1086 * returns uschar * (not nul-terminated)
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.
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
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.
1106 pdkim_headcat(int * col, uschar * str, int * size, int * ptr,
1107 const uschar * pad, const uschar * intro, const uschar * payload)
1115 str = pdkim_hdr_cont(str, size, ptr, col);
1116 str = string_catn(str, size, ptr, pad, l);
1120 l = (pad?1:0) + (intro?Ustrlen(intro):0);
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;
1128 l += payload ? Ustrlen(payload):0 ;
1131 { /* this fragment will not fit on a single line */
1134 str = string_catn(str, size, ptr, US" ", 1);
1136 pad = NULL; /* only want this once */
1142 size_t sl = Ustrlen(intro);
1144 str = string_catn(str, size, ptr, intro, sl);
1147 intro = NULL; /* only want this once */
1152 size_t sl = Ustrlen(payload);
1153 size_t chomp = *col+sl < 77 ? sl : 78-*col;
1155 str = string_catn(str, size, ptr, payload, chomp);
1161 /* the while precondition tells us it didn't fit. */
1162 str = pdkim_hdr_cont(str, size, ptr, col);
1167 str = pdkim_hdr_cont(str, size, ptr, col);
1173 str = string_catn(str, size, ptr, US" ", 1);
1180 size_t sl = Ustrlen(intro);
1182 str = string_catn(str, size, ptr, intro, sl);
1190 size_t sl = Ustrlen(payload);
1192 str = string_catn(str, size, ptr, payload, sl);
1200 /* -------------------------------------------------------------------------- */
1203 pdkim_create_header(pdkim_signature *sig, BOOL final)
1208 uschar * hdr; int hdr_size = 0, hdr_len = 0;
1209 uschar * canon_all; int can_size = 0, can_len = 0;
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';
1218 hdr = string_cat(NULL, &hdr_size, &hdr_len,
1219 US"DKIM-Signature: v="PDKIM_SIGNATURE_VERSION);
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=",
1229 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"d=",
1231 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"s=",
1234 /* list of header names can be split between items. */
1236 uschar * n = string_copy(sig->headernames);
1237 uschar * i = US"h=";
1242 uschar * c = Ustrchr(n, ':');
1247 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, NULL, NULL, US":");
1249 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, s, i, n);
1260 base64_bh = pdkim_encode_base64(&sig->bodyhash);
1261 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"bh=", base64_bh);
1265 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"i=", sig->identity);
1267 if (sig->created > 0)
1271 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->created);
1272 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"t=", minibuf);
1275 if (sig->expires > 0)
1279 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->expires);
1280 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"x=", minibuf);
1283 if (sig->bodylength >= 0)
1287 snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->bodylength);
1288 hdr = pdkim_headcat(&col, hdr, &hdr_size, &hdr_len, US";", US"l=", minibuf);
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);
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"");
1298 hdr[hdr_len] = '\0';
1303 /* -------------------------------------------------------------------------- */
1306 pdkim_feed_finish(pdkim_ctx *ctx, pdkim_signature **return_signatures)
1308 pdkim_signature *sig = ctx->sig;
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)
1315 int rc = pdkim_header_complete(ctx);
1316 if (rc != PDKIM_OK) return rc;
1317 pdkim_update_bodyhash(ctx, "\r\n", 2);
1320 DEBUG(D_acl) debug_printf(
1321 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1323 /* Build (and/or evaluate) body hash */
1324 pdkim_finish_bodyhash(ctx);
1328 BOOL is_sha1 = sig->algo == PDKIM_ALGO_RSA_SHA1;
1330 uschar * sig_hdr = US"";
1333 int hdata_alloc = 0;
1338 exim_sha_init(&hhash_ctx, is_sha1 ? HASH_SHA1 : HASH_SHA256);
1340 DEBUG(D_acl) debug_printf(
1341 "PDKIM >> Header data for hash, canonicalized, in sequence >>>>>>>>>>>>>>\n");
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
1349 if (ctx->flags & PDKIM_MODE_SIGN)
1351 uschar * headernames = NULL; /* Collected signed header names */
1353 pdkim_stringlist *p;
1358 for (p = sig->headers; p; p = p->next)
1359 if (header_name_match(p->value, sig->sign_headers) == PDKIM_OK)
1362 /* Collect header names (Note: colon presence is guaranteed here) */
1363 uschar * q = Ustrchr(p->value, ':');
1365 headernames = string_catn(headernames, &hs, &hl,
1366 p->value, (q - US p->value) + (p->next ? 1 : 0));
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 */
1372 /* Feed header to the hash algorithm */
1373 exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
1375 /* Remember headers block for signing (when the library cannot do incremental) */
1376 (void) exim_rsa_data_append(&hdata, &hdata_alloc, rh);
1378 DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
1381 l = sig->sign_headers;
1382 while((s = string_nextinlist(&l, &sep, NULL, 0)))
1384 { /*SSS string_append_listele() */
1385 if (hl > 0 && headernames[hl-1] != ':')
1386 headernames = string_catn(headernames, &hs, &hl, US":", 1);
1388 headernames = string_cat(headernames, &hs, &hl, s);
1390 headernames[hl] = '\0';
1392 /* Copy headernames to signature struct */
1393 sig->headernames = headernames;
1395 /* Create signature header with b= omitted */
1396 sig_hdr = pdkim_create_header(sig, FALSE);
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. */
1404 uschar * p = sig->headernames;
1406 pdkim_stringlist * hdrs;
1411 for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
1417 if ((q = Ustrchr(p, ':')))
1420 /*XXX walk the list of headers in same order as received. */
1421 for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next)
1423 && strncasecmp(CCS hdrs->value, CCS p, Ustrlen(p)) == 0
1424 && (hdrs->value)[Ustrlen(p)] == ':'
1427 /* cook header for relaxed canon, or just copy it for simple */
1429 uschar * rh = sig->canon_headers == PDKIM_CANON_RELAXED
1430 ? pdkim_relax_header(hdrs->value, 1)
1431 : string_copy(CUS hdrs->value);
1433 /* Feed header to the hash algorithm */
1434 exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh));
1436 DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh));
1445 sig_hdr = string_copy(sig->rawsig_no_b_val);
1449 DEBUG(D_acl) debug_printf(
1450 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1452 /* Relax header if necessary */
1453 if (sig->canon_headers == PDKIM_CANON_RELAXED)
1454 sig_hdr = pdkim_relax_header(sig_hdr, 0);
1459 "PDKIM >> Signed DKIM-Signature header, canonicalized >>>>>>>>>>>>>>>>>\n");
1460 pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr));
1462 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1465 /* Finalize header hash */
1466 exim_sha_update(&hhash_ctx, CUS sig_hdr, Ustrlen(sig_hdr));
1467 exim_sha_finish(&hhash_ctx, &hhash);
1471 debug_printf("PDKIM [%s] Header hash computed: ", sig->domain);
1472 pdkim_hexprint(hhash.data, hhash.len);
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);
1479 /* SIGNING ---------------------------------------------------------------- */
1480 if (ctx->flags & PDKIM_MODE_SIGN)
1483 const uschar * errstr;
1485 /* Import private key */
1486 if ((errstr = exim_rsa_signing_init(US sig->rsa_privkey, &sctx)))
1488 DEBUG(D_acl) debug_printf("signing_init: %s\n", errstr);
1489 return PDKIM_ERR_RSA_PRIVKEY;
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. */
1496 #if defined(RSA_OPENSSL) || defined(RSA_GCRYPT)
1500 if ((errstr = exim_rsa_sign(&sctx, is_sha1, &hdata, &sig->sigdata)))
1502 DEBUG(D_acl) debug_printf("signing: %s\n", errstr);
1503 return PDKIM_ERR_RSA_SIGNING;
1508 debug_printf( "PDKIM [%s] b computed: ", sig->domain);
1509 pdkim_hexprint(sig->sigdata.data, sig->sigdata.len);
1512 sig->signature_header = pdkim_create_header(sig, TRUE);
1515 /* VERIFICATION ----------------------------------------------------------- */
1519 const uschar * errstr;
1522 uschar *dns_txt_name, *dns_txt_reply;
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
1534 sig->verify_status = PDKIM_VERIFY_INVALID;
1535 sig->verify_ext_status = PDKIM_VERIFY_INVALID_SIGNATURE_ERROR;
1537 DEBUG(D_acl) debug_printf(
1538 " Error in DKIM-Signature header: tags missing or invalid\n"
1539 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1543 /* Make sure sig uses supported DKIM version (only v1) */
1544 if (sig->version != 1)
1546 sig->verify_status = PDKIM_VERIFY_INVALID;
1547 sig->verify_ext_status = PDKIM_VERIFY_INVALID_DKIM_VERSION;
1549 DEBUG(D_acl) debug_printf(
1550 " Error in DKIM-Signature header: unsupported DKIM version\n"
1551 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1555 /* Fetch public key for signing domain, from DNS */
1557 dns_txt_name = string_sprintf("%s._domainkey.%s.",
1558 sig->selector, sig->domain);
1560 dns_txt_reply = store_get(PDKIM_DNS_TXT_MAX_RECLEN);
1561 memset(dns_txt_reply, 0, PDKIM_DNS_TXT_MAX_RECLEN);
1563 if ( ctx->dns_txt_callback(CS dns_txt_name, CS dns_txt_reply) != PDKIM_OK
1564 || dns_txt_reply[0] == '\0')
1566 sig->verify_status = PDKIM_VERIFY_INVALID;
1567 sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE;
1574 "PDKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"
1576 pdkim_quoteprint(CUS dns_txt_reply, Ustrlen(dns_txt_reply));
1579 if ( !(p = pdkim_parse_pubkey_record(ctx, CUS dns_txt_reply))
1580 || (Ustrcmp(p->srvtype, "*") != 0 && Ustrcmp(p->srvtype, "email") != 0)
1583 sig->verify_status = PDKIM_VERIFY_INVALID;
1584 sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD;
1589 debug_printf(" Invalid public key service type '%s'\n", p->srvtype);
1591 debug_printf(" Error while parsing public key record\n");
1593 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1599 DEBUG(D_acl) debug_printf(
1600 "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n");
1602 /* Import public key */
1603 if ((errstr = exim_rsa_verify_init(&sig->pubkey->key, &vctx)))
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;
1611 /* Check the signature */
1612 if ((errstr = exim_rsa_verify(&vctx, is_sha1, &hhash, &sig->sigdata)))
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;
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;
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));
1642 /* If requested, set return pointer to signature(s) */
1643 if (return_signatures)
1644 *return_signatures = ctx->sig;
1650 /* -------------------------------------------------------------------------- */
1652 DLLEXPORT pdkim_ctx *
1653 pdkim_init_verify(int(*dns_txt_callback)(char *, char *), BOOL dot_stuffing)
1657 ctx = store_get(sizeof(pdkim_ctx));
1658 memset(ctx, 0, sizeof(pdkim_ctx));
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;
1668 /* -------------------------------------------------------------------------- */
1670 DLLEXPORT pdkim_ctx *
1671 pdkim_init_sign(char *domain, char *selector, char *rsa_privkey, int algo,
1675 pdkim_signature *sig;
1677 if (!domain || !selector || !rsa_privkey)
1680 ctx = store_get(sizeof(pdkim_ctx));
1681 memset(ctx, 0, sizeof(pdkim_ctx));
1683 ctx->flags = dot_stuffed ? PDKIM_MODE_SIGN | PDKIM_DOT_TERM : PDKIM_MODE_SIGN;
1684 ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN);
1686 sig = store_get(sizeof(pdkim_signature));
1687 memset(sig, 0, sizeof(pdkim_signature));
1689 sig->bodylength = -1;
1692 sig->domain = string_copy(US domain);
1693 sig->selector = string_copy(US selector);
1694 sig->rsa_privkey = string_copy(US rsa_privkey);
1697 exim_sha_init(&sig->body_hash, algo == PDKIM_ALGO_RSA_SHA1 ? HASH_SHA1 : HASH_SHA256);
1702 /* -------------------------------------------------------------------------- */
1705 pdkim_set_optional(pdkim_ctx *ctx,
1711 unsigned long created,
1712 unsigned long expires)
1714 pdkim_signature * sig = ctx->sig;
1717 sig->identity = string_copy(US identity);
1719 sig->sign_headers = string_copy(sign_headers
1720 ? US sign_headers : US PDKIM_DEFAULT_SIGN_HEADERS);
1722 sig->canon_headers = canon_headers;
1723 sig->canon_body = canon_body;
1724 sig->bodylength = bodylength;
1725 sig->created = created;
1726 sig->expires = expires;
1740 #endif /*DISABLE_DKIM*/