| 1 | /* |
| 2 | * PDKIM - a RFC4871 (DKIM) implementation |
| 3 | * |
| 4 | * Copyright (C) 2009 - 2016 Tom Kistner <tom@duncanthrax.net> |
| 5 | * Copyright (C) 2016 - 2017 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 SIGN_OPENSSL |
| 36 | # include <openssl/rsa.h> |
| 37 | # include <openssl/ssl.h> |
| 38 | # include <openssl/err.h> |
| 39 | #elif defined(SIGN_GNUTLS) |
| 40 | # include <gnutls/gnutls.h> |
| 41 | # include <gnutls/x509.h> |
| 42 | #endif |
| 43 | |
| 44 | #include "pdkim.h" |
| 45 | #include "signing.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 | |
| 55 | /* -------------------------------------------------------------------------- */ |
| 56 | struct pdkim_stringlist { |
| 57 | uschar * value; |
| 58 | int tag; |
| 59 | void * next; |
| 60 | }; |
| 61 | |
| 62 | /* -------------------------------------------------------------------------- */ |
| 63 | /* A bunch of list constants */ |
| 64 | const uschar * pdkim_querymethods[] = { |
| 65 | US"dns/txt", |
| 66 | NULL |
| 67 | }; |
| 68 | const uschar * pdkim_canons[] = { |
| 69 | US"simple", |
| 70 | US"relaxed", |
| 71 | NULL |
| 72 | }; |
| 73 | |
| 74 | typedef struct { |
| 75 | const uschar * dkim_hashname; |
| 76 | hashmethod exim_hashmethod; |
| 77 | } pdkim_hashtype; |
| 78 | static const pdkim_hashtype pdkim_hashes[] = { |
| 79 | { US"sha1", HASH_SHA1 }, |
| 80 | { US"sha256", HASH_SHA2_256 }, |
| 81 | { US"sha512", HASH_SHA2_512 } |
| 82 | }; |
| 83 | |
| 84 | const uschar * pdkim_keytypes[] = { |
| 85 | US"rsa" |
| 86 | }; |
| 87 | |
| 88 | typedef struct pdkim_combined_canon_entry { |
| 89 | const uschar * str; |
| 90 | int canon_headers; |
| 91 | int canon_body; |
| 92 | } pdkim_combined_canon_entry; |
| 93 | |
| 94 | pdkim_combined_canon_entry pdkim_combined_canons[] = { |
| 95 | { US"simple/simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE }, |
| 96 | { US"simple/relaxed", PDKIM_CANON_SIMPLE, PDKIM_CANON_RELAXED }, |
| 97 | { US"relaxed/simple", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE }, |
| 98 | { US"relaxed/relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_RELAXED }, |
| 99 | { US"simple", PDKIM_CANON_SIMPLE, PDKIM_CANON_SIMPLE }, |
| 100 | { US"relaxed", PDKIM_CANON_RELAXED, PDKIM_CANON_SIMPLE }, |
| 101 | { NULL, 0, 0 } |
| 102 | }; |
| 103 | |
| 104 | |
| 105 | static blob lineending = {.data = US"\r\n", .len = 2}; |
| 106 | |
| 107 | /* -------------------------------------------------------------------------- */ |
| 108 | uschar * |
| 109 | dkim_sig_to_a_tag(const pdkim_signature * sig) |
| 110 | { |
| 111 | if ( sig->keytype < 0 || sig->keytype > nelem(pdkim_keytypes) |
| 112 | || sig->hashtype < 0 || sig->hashtype > nelem(pdkim_hashes)) |
| 113 | return US"err"; |
| 114 | return string_sprintf("%s-%s", |
| 115 | pdkim_keytypes[sig->keytype], pdkim_hashes[sig->hashtype].dkim_hashname); |
| 116 | } |
| 117 | |
| 118 | |
| 119 | |
| 120 | const char * |
| 121 | pdkim_verify_status_str(int status) |
| 122 | { |
| 123 | switch(status) |
| 124 | { |
| 125 | case PDKIM_VERIFY_NONE: return "PDKIM_VERIFY_NONE"; |
| 126 | case PDKIM_VERIFY_INVALID: return "PDKIM_VERIFY_INVALID"; |
| 127 | case PDKIM_VERIFY_FAIL: return "PDKIM_VERIFY_FAIL"; |
| 128 | case PDKIM_VERIFY_PASS: return "PDKIM_VERIFY_PASS"; |
| 129 | default: return "PDKIM_VERIFY_UNKNOWN"; |
| 130 | } |
| 131 | } |
| 132 | |
| 133 | const char * |
| 134 | pdkim_verify_ext_status_str(int ext_status) |
| 135 | { |
| 136 | switch(ext_status) |
| 137 | { |
| 138 | case PDKIM_VERIFY_FAIL_BODY: return "PDKIM_VERIFY_FAIL_BODY"; |
| 139 | case PDKIM_VERIFY_FAIL_MESSAGE: return "PDKIM_VERIFY_FAIL_MESSAGE"; |
| 140 | case PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH: return "PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH"; |
| 141 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: return "PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE"; |
| 142 | case PDKIM_VERIFY_INVALID_BUFFER_SIZE: return "PDKIM_VERIFY_INVALID_BUFFER_SIZE"; |
| 143 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: return "PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD"; |
| 144 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return "PDKIM_VERIFY_INVALID_PUBKEY_IMPORT"; |
| 145 | case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: return "PDKIM_VERIFY_INVALID_SIGNATURE_ERROR"; |
| 146 | case PDKIM_VERIFY_INVALID_DKIM_VERSION: return "PDKIM_VERIFY_INVALID_DKIM_VERSION"; |
| 147 | default: return "PDKIM_VERIFY_UNKNOWN"; |
| 148 | } |
| 149 | } |
| 150 | |
| 151 | const uschar * |
| 152 | pdkim_errstr(int status) |
| 153 | { |
| 154 | switch(status) |
| 155 | { |
| 156 | case PDKIM_OK: return US"OK"; |
| 157 | case PDKIM_FAIL: return US"FAIL"; |
| 158 | case PDKIM_ERR_RSA_PRIVKEY: return US"RSA_PRIVKEY"; |
| 159 | case PDKIM_ERR_RSA_SIGNING: return US"RSA SIGNING"; |
| 160 | case PDKIM_ERR_LONG_LINE: return US"RSA_LONG_LINE"; |
| 161 | case PDKIM_ERR_BUFFER_TOO_SMALL: return US"BUFFER_TOO_SMALL"; |
| 162 | case PDKIM_SIGN_PRIVKEY_WRAP: return US"PRIVKEY_WRAP"; |
| 163 | case PDKIM_SIGN_PRIVKEY_B64D: return US"PRIVKEY_B64D"; |
| 164 | default: return US"(unknown)"; |
| 165 | } |
| 166 | } |
| 167 | |
| 168 | |
| 169 | /* -------------------------------------------------------------------------- */ |
| 170 | /* Print debugging functions */ |
| 171 | static void |
| 172 | pdkim_quoteprint(const uschar *data, int len) |
| 173 | { |
| 174 | int i; |
| 175 | for (i = 0; i < len; i++) |
| 176 | { |
| 177 | const int c = data[i]; |
| 178 | switch (c) |
| 179 | { |
| 180 | case ' ' : debug_printf("{SP}"); break; |
| 181 | case '\t': debug_printf("{TB}"); break; |
| 182 | case '\r': debug_printf("{CR}"); break; |
| 183 | case '\n': debug_printf("{LF}"); break; |
| 184 | case '{' : debug_printf("{BO}"); break; |
| 185 | case '}' : debug_printf("{BC}"); break; |
| 186 | default: |
| 187 | if ( (c < 32) || (c > 127) ) |
| 188 | debug_printf("{%02x}", c); |
| 189 | else |
| 190 | debug_printf("%c", c); |
| 191 | break; |
| 192 | } |
| 193 | } |
| 194 | debug_printf("\n"); |
| 195 | } |
| 196 | |
| 197 | static void |
| 198 | pdkim_hexprint(const uschar *data, int len) |
| 199 | { |
| 200 | int i; |
| 201 | if (data) for (i = 0 ; i < len; i++) debug_printf("%02x", data[i]); |
| 202 | else debug_printf("<NULL>"); |
| 203 | debug_printf("\n"); |
| 204 | } |
| 205 | |
| 206 | |
| 207 | |
| 208 | static pdkim_stringlist * |
| 209 | pdkim_prepend_stringlist(pdkim_stringlist * base, const uschar * str) |
| 210 | { |
| 211 | pdkim_stringlist * new_entry = store_get(sizeof(pdkim_stringlist)); |
| 212 | |
| 213 | memset(new_entry, 0, sizeof(pdkim_stringlist)); |
| 214 | new_entry->value = string_copy(str); |
| 215 | if (base) new_entry->next = base; |
| 216 | return new_entry; |
| 217 | } |
| 218 | |
| 219 | |
| 220 | |
| 221 | /* Trim whitespace fore & aft */ |
| 222 | |
| 223 | static void |
| 224 | pdkim_strtrim(gstring * str) |
| 225 | { |
| 226 | uschar * p = str->s; |
| 227 | uschar * q; |
| 228 | |
| 229 | while (*p == '\t' || *p == ' ') /* dump the leading whitespace */ |
| 230 | { str->size--; str->ptr--; str->s++; } |
| 231 | |
| 232 | while ( str->ptr > 0 |
| 233 | && ((q = str->s + str->ptr - 1), (*q == '\t' || *q == ' ')) |
| 234 | ) |
| 235 | str->ptr--; /* dump trailing whitespace */ |
| 236 | |
| 237 | (void) string_from_gstring(str); |
| 238 | } |
| 239 | |
| 240 | |
| 241 | |
| 242 | /* -------------------------------------------------------------------------- */ |
| 243 | |
| 244 | DLLEXPORT void |
| 245 | pdkim_free_ctx(pdkim_ctx *ctx) |
| 246 | { |
| 247 | } |
| 248 | |
| 249 | |
| 250 | /* -------------------------------------------------------------------------- */ |
| 251 | /* Matches the name of the passed raw "header" against |
| 252 | the passed colon-separated "tick", and invalidates |
| 253 | the entry in tick. Entries can be prefixed for multi- or over-signing, |
| 254 | in which case do not invalidate. |
| 255 | |
| 256 | Returns OK for a match, or fail-code |
| 257 | */ |
| 258 | |
| 259 | static int |
| 260 | header_name_match(const uschar * header, uschar * tick) |
| 261 | { |
| 262 | const uschar * ticklist = tick; |
| 263 | int sep = ':'; |
| 264 | BOOL multisign; |
| 265 | uschar * hname, * p, * ele; |
| 266 | uschar * hcolon = Ustrchr(header, ':'); /* Get header name */ |
| 267 | |
| 268 | if (!hcolon) |
| 269 | return PDKIM_FAIL; /* This isn't a header */ |
| 270 | |
| 271 | /* if we had strncmpic() we wouldn't need this copy */ |
| 272 | hname = string_copyn(header, hcolon-header); |
| 273 | |
| 274 | while (p = US ticklist, ele = string_nextinlist(&ticklist, &sep, NULL, 0)) |
| 275 | { |
| 276 | switch (*ele) |
| 277 | { |
| 278 | case '=': case '+': multisign = TRUE; ele++; break; |
| 279 | default: multisign = FALSE; break; |
| 280 | } |
| 281 | |
| 282 | if (strcmpic(ele, hname) == 0) |
| 283 | { |
| 284 | if (!multisign) |
| 285 | *p = '_'; /* Invalidate this header name instance in tick-off list */ |
| 286 | return PDKIM_OK; |
| 287 | } |
| 288 | } |
| 289 | return PDKIM_FAIL; |
| 290 | } |
| 291 | |
| 292 | |
| 293 | /* -------------------------------------------------------------------------- */ |
| 294 | /* Performs "relaxed" canonicalization of a header. */ |
| 295 | |
| 296 | static uschar * |
| 297 | pdkim_relax_header(const uschar * header, BOOL append_crlf) |
| 298 | { |
| 299 | BOOL past_field_name = FALSE; |
| 300 | BOOL seen_wsp = FALSE; |
| 301 | const uschar * p; |
| 302 | uschar * relaxed = store_get(Ustrlen(header)+3); |
| 303 | uschar * q = relaxed; |
| 304 | |
| 305 | for (p = header; *p; p++) |
| 306 | { |
| 307 | uschar c = *p; |
| 308 | |
| 309 | if (c == '\r' || c == '\n') /* Ignore CR & LF */ |
| 310 | continue; |
| 311 | if (c == '\t' || c == ' ') |
| 312 | { |
| 313 | if (seen_wsp) |
| 314 | continue; |
| 315 | c = ' '; /* Turns WSP into SP */ |
| 316 | seen_wsp = TRUE; |
| 317 | } |
| 318 | else |
| 319 | if (!past_field_name && c == ':') |
| 320 | { |
| 321 | if (seen_wsp) q--; /* This removes WSP immediately before the colon */ |
| 322 | seen_wsp = TRUE; /* This removes WSP immediately after the colon */ |
| 323 | past_field_name = TRUE; |
| 324 | } |
| 325 | else |
| 326 | seen_wsp = FALSE; |
| 327 | |
| 328 | /* Lowercase header name */ |
| 329 | if (!past_field_name) c = tolower(c); |
| 330 | *q++ = c; |
| 331 | } |
| 332 | |
| 333 | if (q > relaxed && q[-1] == ' ') q--; /* Squash eventual trailing SP */ |
| 334 | |
| 335 | if (append_crlf) { *q++ = '\r'; *q++ = '\n'; } |
| 336 | *q = '\0'; |
| 337 | return relaxed; |
| 338 | } |
| 339 | |
| 340 | |
| 341 | /* -------------------------------------------------------------------------- */ |
| 342 | #define PDKIM_QP_ERROR_DECODE -1 |
| 343 | |
| 344 | static const uschar * |
| 345 | pdkim_decode_qp_char(const uschar *qp_p, int *c) |
| 346 | { |
| 347 | const uschar *initial_pos = qp_p; |
| 348 | |
| 349 | /* Advance one char */ |
| 350 | qp_p++; |
| 351 | |
| 352 | /* Check for two hex digits and decode them */ |
| 353 | if (isxdigit(*qp_p) && isxdigit(qp_p[1])) |
| 354 | { |
| 355 | /* Do hex conversion */ |
| 356 | *c = (isdigit(*qp_p) ? *qp_p - '0' : toupper(*qp_p) - 'A' + 10) << 4; |
| 357 | *c |= isdigit(qp_p[1]) ? qp_p[1] - '0' : toupper(qp_p[1]) - 'A' + 10; |
| 358 | return qp_p + 2; |
| 359 | } |
| 360 | |
| 361 | /* Illegal char here */ |
| 362 | *c = PDKIM_QP_ERROR_DECODE; |
| 363 | return initial_pos; |
| 364 | } |
| 365 | |
| 366 | |
| 367 | /* -------------------------------------------------------------------------- */ |
| 368 | |
| 369 | static uschar * |
| 370 | pdkim_decode_qp(const uschar * str) |
| 371 | { |
| 372 | int nchar = 0; |
| 373 | uschar * q; |
| 374 | const uschar * p = str; |
| 375 | uschar * n = store_get(Ustrlen(str)+1); |
| 376 | |
| 377 | *n = '\0'; |
| 378 | q = n; |
| 379 | while (*p) |
| 380 | { |
| 381 | if (*p == '=') |
| 382 | { |
| 383 | p = pdkim_decode_qp_char(p, &nchar); |
| 384 | if (nchar >= 0) |
| 385 | { |
| 386 | *q++ = nchar; |
| 387 | continue; |
| 388 | } |
| 389 | } |
| 390 | else |
| 391 | *q++ = *p; |
| 392 | p++; |
| 393 | } |
| 394 | *q = '\0'; |
| 395 | return n; |
| 396 | } |
| 397 | |
| 398 | |
| 399 | /* -------------------------------------------------------------------------- */ |
| 400 | |
| 401 | static void |
| 402 | pdkim_decode_base64(const uschar * str, blob * b) |
| 403 | { |
| 404 | int dlen; |
| 405 | dlen = b64decode(str, &b->data); |
| 406 | if (dlen < 0) b->data = NULL; |
| 407 | b->len = dlen; |
| 408 | } |
| 409 | |
| 410 | static uschar * |
| 411 | pdkim_encode_base64(blob * b) |
| 412 | { |
| 413 | return b64encode(b->data, b->len); |
| 414 | } |
| 415 | |
| 416 | |
| 417 | /* -------------------------------------------------------------------------- */ |
| 418 | #define PDKIM_HDR_LIMBO 0 |
| 419 | #define PDKIM_HDR_TAG 1 |
| 420 | #define PDKIM_HDR_VALUE 2 |
| 421 | |
| 422 | static pdkim_signature * |
| 423 | pdkim_parse_sig_header(pdkim_ctx * ctx, uschar * raw_hdr) |
| 424 | { |
| 425 | pdkim_signature * sig; |
| 426 | uschar *p, *q; |
| 427 | gstring * cur_tag = NULL; |
| 428 | gstring * cur_val = NULL; |
| 429 | BOOL past_hname = FALSE; |
| 430 | BOOL in_b_val = FALSE; |
| 431 | int where = PDKIM_HDR_LIMBO; |
| 432 | int i; |
| 433 | |
| 434 | sig = store_get(sizeof(pdkim_signature)); |
| 435 | memset(sig, 0, sizeof(pdkim_signature)); |
| 436 | sig->bodylength = -1; |
| 437 | |
| 438 | /* Set so invalid/missing data error display is accurate */ |
| 439 | sig->version = 0; |
| 440 | sig->keytype = -1; |
| 441 | sig->hashtype = -1; |
| 442 | |
| 443 | q = sig->rawsig_no_b_val = store_get(Ustrlen(raw_hdr)+1); |
| 444 | |
| 445 | for (p = raw_hdr; ; p++) |
| 446 | { |
| 447 | char c = *p; |
| 448 | |
| 449 | /* Ignore FWS */ |
| 450 | if (c == '\r' || c == '\n') |
| 451 | goto NEXT_CHAR; |
| 452 | |
| 453 | /* Fast-forward through header name */ |
| 454 | if (!past_hname) |
| 455 | { |
| 456 | if (c == ':') past_hname = TRUE; |
| 457 | goto NEXT_CHAR; |
| 458 | } |
| 459 | |
| 460 | if (where == PDKIM_HDR_LIMBO) |
| 461 | { |
| 462 | /* In limbo, just wait for a tag-char to appear */ |
| 463 | if (!(c >= 'a' && c <= 'z')) |
| 464 | goto NEXT_CHAR; |
| 465 | |
| 466 | where = PDKIM_HDR_TAG; |
| 467 | } |
| 468 | |
| 469 | if (where == PDKIM_HDR_TAG) |
| 470 | { |
| 471 | if (c >= 'a' && c <= 'z') |
| 472 | cur_tag = string_catn(cur_tag, p, 1); |
| 473 | |
| 474 | if (c == '=') |
| 475 | { |
| 476 | if (Ustrcmp(string_from_gstring(cur_tag), "b") == 0) |
| 477 | { |
| 478 | *q++ = '='; |
| 479 | in_b_val = TRUE; |
| 480 | } |
| 481 | where = PDKIM_HDR_VALUE; |
| 482 | goto NEXT_CHAR; |
| 483 | } |
| 484 | } |
| 485 | |
| 486 | if (where == PDKIM_HDR_VALUE) |
| 487 | { |
| 488 | if (c == '\r' || c == '\n' || c == ' ' || c == '\t') |
| 489 | goto NEXT_CHAR; |
| 490 | |
| 491 | if (c == ';' || c == '\0') |
| 492 | { |
| 493 | /* We must have both tag and value, and tags must be one char except |
| 494 | for the possibility of "bh". */ |
| 495 | |
| 496 | if ( cur_tag && cur_val |
| 497 | && (cur_tag->ptr == 1 || *cur_tag->s == 'b') |
| 498 | ) |
| 499 | { |
| 500 | (void) string_from_gstring(cur_val); |
| 501 | pdkim_strtrim(cur_val); |
| 502 | |
| 503 | DEBUG(D_acl) debug_printf(" %s=%s\n", cur_tag->s, cur_val->s); |
| 504 | |
| 505 | switch (*cur_tag->s) |
| 506 | { |
| 507 | case 'b': |
| 508 | switch (cur_tag->s[1]) |
| 509 | { |
| 510 | case '\0': pdkim_decode_base64(cur_val->s, &sig->sighash); break; |
| 511 | case 'h': if (cur_tag->ptr == 2) |
| 512 | pdkim_decode_base64(cur_val->s, &sig->bodyhash); |
| 513 | break; |
| 514 | default: break; |
| 515 | } |
| 516 | break; |
| 517 | case 'v': |
| 518 | /* We only support version 1, and that is currently the |
| 519 | only version there is. */ |
| 520 | sig->version = |
| 521 | Ustrcmp(cur_val->s, PDKIM_SIGNATURE_VERSION) == 0 ? 1 : -1; |
| 522 | break; |
| 523 | case 'a': |
| 524 | { |
| 525 | uschar * s = Ustrchr(cur_val->s, '-'); |
| 526 | |
| 527 | for(i = 0; i < nelem(pdkim_keytypes); i++) |
| 528 | if (Ustrncmp(cur_val->s, pdkim_keytypes[i], s - cur_val->s) == 0) |
| 529 | { sig->keytype = i; break; } |
| 530 | for (++s, i = 0; i < nelem(pdkim_hashes); i++) |
| 531 | if (Ustrcmp(s, pdkim_hashes[i].dkim_hashname) == 0) |
| 532 | { sig->hashtype = i; break; } |
| 533 | break; |
| 534 | } |
| 535 | |
| 536 | case 'c': |
| 537 | for (i = 0; pdkim_combined_canons[i].str; i++) |
| 538 | if (Ustrcmp(cur_val->s, pdkim_combined_canons[i].str) == 0) |
| 539 | { |
| 540 | sig->canon_headers = pdkim_combined_canons[i].canon_headers; |
| 541 | sig->canon_body = pdkim_combined_canons[i].canon_body; |
| 542 | break; |
| 543 | } |
| 544 | break; |
| 545 | case 'q': |
| 546 | for (i = 0; pdkim_querymethods[i]; i++) |
| 547 | if (Ustrcmp(cur_val->s, pdkim_querymethods[i]) == 0) |
| 548 | { |
| 549 | sig->querymethod = i; |
| 550 | break; |
| 551 | } |
| 552 | break; |
| 553 | case 's': |
| 554 | sig->selector = string_copyn(cur_val->s, cur_val->ptr); break; |
| 555 | case 'd': |
| 556 | sig->domain = string_copyn(cur_val->s, cur_val->ptr); break; |
| 557 | case 'i': |
| 558 | sig->identity = pdkim_decode_qp(cur_val->s); break; |
| 559 | case 't': |
| 560 | sig->created = strtoul(CS cur_val->s, NULL, 10); break; |
| 561 | case 'x': |
| 562 | sig->expires = strtoul(CS cur_val->s, NULL, 10); break; |
| 563 | case 'l': |
| 564 | sig->bodylength = strtol(CS cur_val->s, NULL, 10); break; |
| 565 | case 'h': |
| 566 | sig->headernames = string_copyn(cur_val->s, cur_val->ptr); break; |
| 567 | case 'z': |
| 568 | sig->copiedheaders = pdkim_decode_qp(cur_val->s); break; |
| 569 | default: |
| 570 | DEBUG(D_acl) debug_printf(" Unknown tag encountered\n"); |
| 571 | break; |
| 572 | } |
| 573 | } |
| 574 | cur_tag = cur_val = NULL; |
| 575 | in_b_val = FALSE; |
| 576 | where = PDKIM_HDR_LIMBO; |
| 577 | } |
| 578 | else |
| 579 | cur_val = string_catn(cur_val, p, 1); |
| 580 | } |
| 581 | |
| 582 | NEXT_CHAR: |
| 583 | if (c == '\0') |
| 584 | break; |
| 585 | |
| 586 | if (!in_b_val) |
| 587 | *q++ = c; |
| 588 | } |
| 589 | |
| 590 | *q = '\0'; |
| 591 | /* Chomp raw header. The final newline must not be added to the signature. */ |
| 592 | while (--q > sig->rawsig_no_b_val && (*q == '\r' || *q == '\n')) |
| 593 | *q = '\0'; |
| 594 | |
| 595 | DEBUG(D_acl) |
| 596 | { |
| 597 | debug_printf( |
| 598 | "PDKIM >> Raw signature w/o b= tag value >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); |
| 599 | pdkim_quoteprint(US sig->rawsig_no_b_val, Ustrlen(sig->rawsig_no_b_val)); |
| 600 | debug_printf( |
| 601 | "PDKIM >> Sig size: %4u bits\n", (unsigned) sig->sighash.len*8); |
| 602 | debug_printf( |
| 603 | "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); |
| 604 | } |
| 605 | |
| 606 | /*XXX hash method: extend for sha512 */ |
| 607 | if (!exim_sha_init(&sig->body_hash_ctx, |
| 608 | pdkim_hashes[sig->hashtype].exim_hashmethod)) |
| 609 | { |
| 610 | DEBUG(D_acl) |
| 611 | debug_printf("PDKIM: hash init error, possibly nonhandled hashtype\n"); |
| 612 | return NULL; |
| 613 | } |
| 614 | return sig; |
| 615 | } |
| 616 | |
| 617 | |
| 618 | /* -------------------------------------------------------------------------- */ |
| 619 | |
| 620 | static pdkim_pubkey * |
| 621 | pdkim_parse_pubkey_record(pdkim_ctx *ctx, const uschar *raw_record) |
| 622 | { |
| 623 | const uschar * ele; |
| 624 | int sep = ';'; |
| 625 | pdkim_pubkey * pub; |
| 626 | |
| 627 | pub = store_get(sizeof(pdkim_pubkey)); |
| 628 | memset(pub, 0, sizeof(pdkim_pubkey)); |
| 629 | |
| 630 | while ((ele = string_nextinlist(&raw_record, &sep, NULL, 0))) |
| 631 | { |
| 632 | const uschar * val; |
| 633 | |
| 634 | if ((val = Ustrchr(ele, '='))) |
| 635 | { |
| 636 | int taglen = val++ - ele; |
| 637 | |
| 638 | DEBUG(D_acl) debug_printf(" %.*s=%s\n", taglen, ele, val); |
| 639 | switch (ele[0]) |
| 640 | { |
| 641 | case 'v': pub->version = val; break; |
| 642 | case 'h': pub->hashes = val; break; |
| 643 | case 'k': break; |
| 644 | case 'g': pub->granularity = val; break; |
| 645 | case 'n': pub->notes = pdkim_decode_qp(val); break; |
| 646 | case 'p': pdkim_decode_base64(val, &pub->key); break; |
| 647 | case 's': pub->srvtype = val; break; |
| 648 | case 't': if (Ustrchr(val, 'y')) pub->testing = 1; |
| 649 | if (Ustrchr(val, 's')) pub->no_subdomaining = 1; |
| 650 | break; |
| 651 | default: DEBUG(D_acl) debug_printf(" Unknown tag encountered\n"); break; |
| 652 | } |
| 653 | } |
| 654 | } |
| 655 | |
| 656 | /* Set fallback defaults */ |
| 657 | if (!pub->version) |
| 658 | pub->version = string_copy(PDKIM_PUB_RECORD_VERSION); |
| 659 | else if (Ustrcmp(pub->version, PDKIM_PUB_RECORD_VERSION) != 0) |
| 660 | { |
| 661 | DEBUG(D_acl) debug_printf(" Bad v= field\n"); |
| 662 | return NULL; |
| 663 | } |
| 664 | |
| 665 | if (!pub->granularity) pub->granularity = US"*"; |
| 666 | /* |
| 667 | if (!pub->keytype ) pub->keytype = US"rsa"; |
| 668 | */ |
| 669 | if (!pub->srvtype ) pub->srvtype = US"*"; |
| 670 | |
| 671 | /* p= is required */ |
| 672 | if (pub->key.data) |
| 673 | return pub; |
| 674 | |
| 675 | DEBUG(D_acl) debug_printf(" Missing p= field\n"); |
| 676 | return NULL; |
| 677 | } |
| 678 | |
| 679 | |
| 680 | /* -------------------------------------------------------------------------- */ |
| 681 | |
| 682 | /* Update the bodyhash for one sig, with some additional data. |
| 683 | If we have to relax the data for this sig, return our copy of it. */ |
| 684 | |
| 685 | /*XXX Currently we calculate a hash for each sig. But it is possible |
| 686 | that multi-signing will be wanted using different signing algos |
| 687 | (rsa, ec) using the same hash and canonicalization. Consider in future |
| 688 | hanging the hash+cacnon from the ctx and only referencing from the sig, |
| 689 | so that it can be calculated only once - being over the body this |
| 690 | caould be meagbytes, hence expensive. */ |
| 691 | |
| 692 | static blob * |
| 693 | pdkim_update_sig_bodyhash(pdkim_signature * sig, blob * orig_data, blob * relaxed_data) |
| 694 | { |
| 695 | blob * canon_data = orig_data; |
| 696 | /* Defaults to simple canon (no further treatment necessary) */ |
| 697 | |
| 698 | if (sig->canon_body == PDKIM_CANON_RELAXED) |
| 699 | { |
| 700 | /* Relax the line if not done already */ |
| 701 | if (!relaxed_data) |
| 702 | { |
| 703 | BOOL seen_wsp = FALSE; |
| 704 | const uschar * p; |
| 705 | int q = 0; |
| 706 | |
| 707 | /* We want to be able to free this else we allocate |
| 708 | for the entire message which could be many MB. Since |
| 709 | we don't know what allocations the SHA routines might |
| 710 | do, not safe to use store_get()/store_reset(). */ |
| 711 | |
| 712 | relaxed_data = store_malloc(sizeof(blob) + orig_data->len+1); |
| 713 | relaxed_data->data = US (relaxed_data+1); |
| 714 | |
| 715 | for (p = orig_data->data; *p; p++) |
| 716 | { |
| 717 | char c = *p; |
| 718 | if (c == '\r') |
| 719 | { |
| 720 | if (q > 0 && relaxed_data->data[q-1] == ' ') |
| 721 | q--; |
| 722 | } |
| 723 | else if (c == '\t' || c == ' ') |
| 724 | { |
| 725 | c = ' '; /* Turns WSP into SP */ |
| 726 | if (seen_wsp) |
| 727 | continue; |
| 728 | seen_wsp = TRUE; |
| 729 | } |
| 730 | else |
| 731 | seen_wsp = FALSE; |
| 732 | relaxed_data->data[q++] = c; |
| 733 | } |
| 734 | relaxed_data->data[q] = '\0'; |
| 735 | relaxed_data->len = q; |
| 736 | } |
| 737 | canon_data = relaxed_data; |
| 738 | } |
| 739 | |
| 740 | /* Make sure we don't exceed the to-be-signed body length */ |
| 741 | if ( sig->bodylength >= 0 |
| 742 | && sig->signed_body_bytes + (unsigned long)canon_data->len > sig->bodylength |
| 743 | ) |
| 744 | canon_data->len = sig->bodylength - sig->signed_body_bytes; |
| 745 | |
| 746 | if (canon_data->len > 0) |
| 747 | { |
| 748 | exim_sha_update(&sig->body_hash_ctx, CUS canon_data->data, canon_data->len); |
| 749 | sig->signed_body_bytes += canon_data->len; |
| 750 | DEBUG(D_acl) pdkim_quoteprint(canon_data->data, canon_data->len); |
| 751 | } |
| 752 | |
| 753 | return relaxed_data; |
| 754 | } |
| 755 | |
| 756 | |
| 757 | /* -------------------------------------------------------------------------- */ |
| 758 | |
| 759 | static void |
| 760 | pdkim_finish_bodyhash(pdkim_ctx * ctx) |
| 761 | { |
| 762 | pdkim_signature * sig; |
| 763 | |
| 764 | /* Traverse all signatures */ |
| 765 | for (sig = ctx->sig; sig; sig = sig->next) |
| 766 | { /* Finish hashes */ |
| 767 | blob bh; |
| 768 | |
| 769 | exim_sha_finish(&sig->body_hash_ctx, &bh); |
| 770 | |
| 771 | DEBUG(D_acl) |
| 772 | { |
| 773 | debug_printf("PDKIM [%s] Body bytes hashed: %lu\n" |
| 774 | "PDKIM [%s] Body %s computed: ", |
| 775 | sig->domain, sig->signed_body_bytes, |
| 776 | sig->domain, pdkim_hashes[sig->hashtype].dkim_hashname); |
| 777 | pdkim_hexprint(CUS bh.data, bh.len); |
| 778 | } |
| 779 | |
| 780 | /* SIGNING -------------------------------------------------------------- */ |
| 781 | if (ctx->flags & PDKIM_MODE_SIGN) |
| 782 | { |
| 783 | sig->bodyhash = bh; |
| 784 | |
| 785 | /* If bodylength limit is set, and we have received less bytes |
| 786 | than the requested amount, effectively remove the limit tag. */ |
| 787 | if (sig->signed_body_bytes < sig->bodylength) |
| 788 | sig->bodylength = -1; |
| 789 | } |
| 790 | |
| 791 | else |
| 792 | /* VERIFICATION --------------------------------------------------------- */ |
| 793 | /* Be careful that the header sig included a bodyash */ |
| 794 | |
| 795 | if (sig->bodyhash.data && memcmp(bh.data, sig->bodyhash.data, bh.len) == 0) |
| 796 | { |
| 797 | DEBUG(D_acl) debug_printf("PDKIM [%s] Body hash verified OK\n", sig->domain); |
| 798 | } |
| 799 | else |
| 800 | { |
| 801 | DEBUG(D_acl) |
| 802 | { |
| 803 | debug_printf("PDKIM [%s] Body hash signature from headers: ", sig->domain); |
| 804 | pdkim_hexprint(sig->bodyhash.data, sig->bodyhash.len); |
| 805 | debug_printf("PDKIM [%s] Body hash did NOT verify\n", sig->domain); |
| 806 | } |
| 807 | sig->verify_status = PDKIM_VERIFY_FAIL; |
| 808 | sig->verify_ext_status = PDKIM_VERIFY_FAIL_BODY; |
| 809 | } |
| 810 | } |
| 811 | } |
| 812 | |
| 813 | |
| 814 | |
| 815 | static void |
| 816 | pdkim_body_complete(pdkim_ctx * ctx) |
| 817 | { |
| 818 | pdkim_signature * sig; |
| 819 | |
| 820 | /* In simple body mode, if any empty lines were buffered, |
| 821 | replace with one. rfc 4871 3.4.3 */ |
| 822 | /*XXX checking the signed-body-bytes is a gross hack; I think |
| 823 | it indicates that all linebreaks should be buffered, including |
| 824 | the one terminating a text line */ |
| 825 | |
| 826 | for (sig = ctx->sig; sig; sig = sig->next) |
| 827 | if ( sig->canon_body == PDKIM_CANON_SIMPLE |
| 828 | && sig->signed_body_bytes == 0 |
| 829 | && sig->num_buffered_blanklines > 0 |
| 830 | ) |
| 831 | (void) pdkim_update_sig_bodyhash(sig, &lineending, NULL); |
| 832 | |
| 833 | ctx->flags |= PDKIM_SEEN_EOD; |
| 834 | ctx->linebuf_offset = 0; |
| 835 | } |
| 836 | |
| 837 | |
| 838 | |
| 839 | /* -------------------------------------------------------------------------- */ |
| 840 | /* Call from pdkim_feed below for processing complete body lines */ |
| 841 | |
| 842 | static void |
| 843 | pdkim_bodyline_complete(pdkim_ctx * ctx) |
| 844 | { |
| 845 | blob line = {.data = ctx->linebuf, .len = ctx->linebuf_offset}; |
| 846 | pdkim_signature * sig; |
| 847 | blob * rnl = NULL; |
| 848 | blob * rline = NULL; |
| 849 | |
| 850 | /* Ignore extra data if we've seen the end-of-data marker */ |
| 851 | if (ctx->flags & PDKIM_SEEN_EOD) goto all_skip; |
| 852 | |
| 853 | /* We've always got one extra byte to stuff a zero ... */ |
| 854 | ctx->linebuf[line.len] = '\0'; |
| 855 | |
| 856 | /* Terminate on EOD marker */ |
| 857 | if (ctx->flags & PDKIM_DOT_TERM) |
| 858 | { |
| 859 | if (memcmp(line.data, ".\r\n", 3) == 0) |
| 860 | { pdkim_body_complete(ctx); return; } |
| 861 | |
| 862 | /* Unstuff dots */ |
| 863 | if (memcmp(line.data, "..", 2) == 0) |
| 864 | { line.data++; line.len--; } |
| 865 | } |
| 866 | |
| 867 | /* Empty lines need to be buffered until we find a non-empty line */ |
| 868 | if (memcmp(line.data, "\r\n", 2) == 0) |
| 869 | { |
| 870 | for (sig = ctx->sig; sig; sig = sig->next) sig->num_buffered_blanklines++; |
| 871 | goto all_skip; |
| 872 | } |
| 873 | |
| 874 | /* Process line for each sig separately */ |
| 875 | for (sig = ctx->sig; sig; sig = sig->next) |
| 876 | { |
| 877 | if (sig->canon_body == PDKIM_CANON_RELAXED) |
| 878 | { |
| 879 | /* Lines with just spaces need to be buffered too */ |
| 880 | uschar * cp = line.data; |
| 881 | char c; |
| 882 | |
| 883 | while ((c = *cp)) |
| 884 | { |
| 885 | if (c == '\r' && cp[1] == '\n') break; |
| 886 | if (c != ' ' && c != '\t') goto sig_process; |
| 887 | cp++; |
| 888 | } |
| 889 | |
| 890 | sig->num_buffered_blanklines++; |
| 891 | goto sig_skip; |
| 892 | } |
| 893 | |
| 894 | sig_process: |
| 895 | /* At this point, we have a non-empty line, so release the buffered ones. */ |
| 896 | |
| 897 | while (sig->num_buffered_blanklines) |
| 898 | { |
| 899 | rnl = pdkim_update_sig_bodyhash(sig, &lineending, rnl); |
| 900 | sig->num_buffered_blanklines--; |
| 901 | } |
| 902 | |
| 903 | rline = pdkim_update_sig_bodyhash(sig, &line, rline); |
| 904 | sig_skip: ; |
| 905 | } |
| 906 | |
| 907 | if (rnl) store_free(rnl); |
| 908 | if (rline) store_free(rline); |
| 909 | |
| 910 | all_skip: |
| 911 | |
| 912 | ctx->linebuf_offset = 0; |
| 913 | return; |
| 914 | } |
| 915 | |
| 916 | |
| 917 | /* -------------------------------------------------------------------------- */ |
| 918 | /* Callback from pdkim_feed below for processing complete headers */ |
| 919 | #define DKIM_SIGNATURE_HEADERNAME "DKIM-Signature:" |
| 920 | |
| 921 | static int |
| 922 | pdkim_header_complete(pdkim_ctx * ctx) |
| 923 | { |
| 924 | pdkim_signature * sig, * last_sig; |
| 925 | |
| 926 | /* Special case: The last header can have an extra \r appended */ |
| 927 | if ( (ctx->cur_header->ptr > 1) && |
| 928 | (ctx->cur_header->s[ctx->cur_header->ptr-1] == '\r') ) |
| 929 | --ctx->cur_header->ptr; |
| 930 | (void) string_from_gstring(ctx->cur_header); |
| 931 | |
| 932 | if (++ctx->num_headers > PDKIM_MAX_HEADERS) goto BAIL; |
| 933 | |
| 934 | /* SIGNING -------------------------------------------------------------- */ |
| 935 | if (ctx->flags & PDKIM_MODE_SIGN) |
| 936 | for (sig = ctx->sig; sig; sig = sig->next) /* Traverse all signatures */ |
| 937 | |
| 938 | /* Add header to the signed headers list (in reverse order) */ |
| 939 | sig->headers = pdkim_prepend_stringlist(sig->headers, ctx->cur_header->s); |
| 940 | |
| 941 | /* VERIFICATION ----------------------------------------------------------- */ |
| 942 | /* DKIM-Signature: headers are added to the verification list */ |
| 943 | else |
| 944 | { |
| 945 | #ifdef notdef |
| 946 | DEBUG(D_acl) |
| 947 | { |
| 948 | debug_printf("PDKIM >> raw hdr: "); |
| 949 | pdkim_quoteprint(CUS ctx->cur_header->s, ctx->cur_header->ptr); |
| 950 | } |
| 951 | #endif |
| 952 | if (strncasecmp(CCS ctx->cur_header->s, |
| 953 | DKIM_SIGNATURE_HEADERNAME, |
| 954 | Ustrlen(DKIM_SIGNATURE_HEADERNAME)) == 0) |
| 955 | { |
| 956 | /* Create and chain new signature block. We could error-check for all |
| 957 | required tags here, but prefer to create the internal sig and expicitly |
| 958 | fail verification of it later. */ |
| 959 | |
| 960 | DEBUG(D_acl) debug_printf( |
| 961 | "PDKIM >> Found sig, trying to parse >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); |
| 962 | |
| 963 | sig = pdkim_parse_sig_header(ctx, ctx->cur_header->s); |
| 964 | |
| 965 | if (!(last_sig = ctx->sig)) |
| 966 | ctx->sig = sig; |
| 967 | else |
| 968 | { |
| 969 | while (last_sig->next) last_sig = last_sig->next; |
| 970 | last_sig->next = sig; |
| 971 | } |
| 972 | } |
| 973 | |
| 974 | /* all headers are stored for signature verification */ |
| 975 | ctx->headers = pdkim_prepend_stringlist(ctx->headers, ctx->cur_header->s); |
| 976 | } |
| 977 | |
| 978 | BAIL: |
| 979 | ctx->cur_header->s[ctx->cur_header->ptr = 0] = '\0'; /* leave buffer for reuse */ |
| 980 | return PDKIM_OK; |
| 981 | } |
| 982 | |
| 983 | |
| 984 | |
| 985 | /* -------------------------------------------------------------------------- */ |
| 986 | #define HEADER_BUFFER_FRAG_SIZE 256 |
| 987 | |
| 988 | DLLEXPORT int |
| 989 | pdkim_feed(pdkim_ctx * ctx, uschar * data, int len) |
| 990 | { |
| 991 | int p, rc; |
| 992 | |
| 993 | /* Alternate EOD signal, used in non-dotstuffing mode */ |
| 994 | if (!data) |
| 995 | pdkim_body_complete(ctx); |
| 996 | |
| 997 | else for (p = 0; p<len; p++) |
| 998 | { |
| 999 | uschar c = data[p]; |
| 1000 | |
| 1001 | if (ctx->flags & PDKIM_PAST_HDRS) |
| 1002 | { |
| 1003 | if (c == '\n' && !(ctx->flags & PDKIM_SEEN_CR)) /* emulate the CR */ |
| 1004 | { |
| 1005 | ctx->linebuf[ctx->linebuf_offset++] = '\r'; |
| 1006 | if (ctx->linebuf_offset == PDKIM_MAX_BODY_LINE_LEN-1) |
| 1007 | return PDKIM_ERR_LONG_LINE; |
| 1008 | } |
| 1009 | |
| 1010 | /* Processing body byte */ |
| 1011 | ctx->linebuf[ctx->linebuf_offset++] = c; |
| 1012 | if (c == '\r') |
| 1013 | ctx->flags |= PDKIM_SEEN_CR; |
| 1014 | else if (c == '\n') |
| 1015 | { |
| 1016 | ctx->flags &= ~PDKIM_SEEN_CR; |
| 1017 | pdkim_bodyline_complete(ctx); |
| 1018 | } |
| 1019 | |
| 1020 | if (ctx->linebuf_offset == PDKIM_MAX_BODY_LINE_LEN-1) |
| 1021 | return PDKIM_ERR_LONG_LINE; |
| 1022 | } |
| 1023 | else |
| 1024 | { |
| 1025 | /* Processing header byte */ |
| 1026 | if (c == '\r') |
| 1027 | ctx->flags |= PDKIM_SEEN_CR; |
| 1028 | else if (c == '\n') |
| 1029 | { |
| 1030 | if (!(ctx->flags & PDKIM_SEEN_CR)) /* emulate the CR */ |
| 1031 | ctx->cur_header = string_catn(ctx->cur_header, CUS "\r", 1); |
| 1032 | |
| 1033 | if (ctx->flags & PDKIM_SEEN_LF) /* Seen last header line */ |
| 1034 | { |
| 1035 | if ((rc = pdkim_header_complete(ctx)) != PDKIM_OK) |
| 1036 | return rc; |
| 1037 | |
| 1038 | ctx->flags = (ctx->flags & ~(PDKIM_SEEN_LF|PDKIM_SEEN_CR)) | PDKIM_PAST_HDRS; |
| 1039 | DEBUG(D_acl) debug_printf( |
| 1040 | "PDKIM >> Body data for hash, canonicalized >>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); |
| 1041 | continue; |
| 1042 | } |
| 1043 | else |
| 1044 | ctx->flags = (ctx->flags & ~PDKIM_SEEN_CR) | PDKIM_SEEN_LF; |
| 1045 | } |
| 1046 | else if (ctx->flags & PDKIM_SEEN_LF) |
| 1047 | { |
| 1048 | if (!(c == '\t' || c == ' ')) /* End of header */ |
| 1049 | if ((rc = pdkim_header_complete(ctx)) != PDKIM_OK) |
| 1050 | return rc; |
| 1051 | ctx->flags &= ~PDKIM_SEEN_LF; |
| 1052 | } |
| 1053 | |
| 1054 | if (!ctx->cur_header || ctx->cur_header->ptr < PDKIM_MAX_HEADER_LEN) |
| 1055 | ctx->cur_header = string_catn(ctx->cur_header, CUS &data[p], 1); |
| 1056 | } |
| 1057 | } |
| 1058 | return PDKIM_OK; |
| 1059 | } |
| 1060 | |
| 1061 | |
| 1062 | |
| 1063 | /* Extend a growing header with a continuation-linebreak */ |
| 1064 | static gstring * |
| 1065 | pdkim_hdr_cont(gstring * str, int * col) |
| 1066 | { |
| 1067 | *col = 1; |
| 1068 | return string_catn(str, US"\r\n\t", 3); |
| 1069 | } |
| 1070 | |
| 1071 | |
| 1072 | |
| 1073 | /* |
| 1074 | * RFC 5322 specifies that header line length SHOULD be no more than 78 |
| 1075 | * lets make it so! |
| 1076 | * pdkim_headcat |
| 1077 | * |
| 1078 | * returns uschar * (not nul-terminated) |
| 1079 | * |
| 1080 | * col: this int holds and receives column number (octets since last '\n') |
| 1081 | * str: partial string to append to |
| 1082 | * pad: padding, split line or space after before or after eg: ";" |
| 1083 | * intro: - must join to payload eg "h=", usually the tag name |
| 1084 | * payload: eg base64 data - long data can be split arbitrarily. |
| 1085 | * |
| 1086 | * this code doesn't fold the header in some of the places that RFC4871 |
| 1087 | * allows: As per RFC5322(2.2.3) it only folds before or after tag-value |
| 1088 | * pairs and inside long values. it also always spaces or breaks after the |
| 1089 | * "pad" |
| 1090 | * |
| 1091 | * no guarantees are made for output given out-of range input. like tag |
| 1092 | * names longer than 78, or bogus col. Input is assumed to be free of line breaks. |
| 1093 | */ |
| 1094 | |
| 1095 | static gstring * |
| 1096 | pdkim_headcat(int * col, gstring * str, |
| 1097 | const uschar * pad, const uschar * intro, const uschar * payload) |
| 1098 | { |
| 1099 | size_t l; |
| 1100 | |
| 1101 | if (pad) |
| 1102 | { |
| 1103 | l = Ustrlen(pad); |
| 1104 | if (*col + l > 78) |
| 1105 | str = pdkim_hdr_cont(str, col); |
| 1106 | str = string_catn(str, pad, l); |
| 1107 | *col += l; |
| 1108 | } |
| 1109 | |
| 1110 | l = (pad?1:0) + (intro?Ustrlen(intro):0); |
| 1111 | |
| 1112 | if (*col + l > 78) |
| 1113 | { /*can't fit intro - start a new line to make room.*/ |
| 1114 | str = pdkim_hdr_cont(str, col); |
| 1115 | l = intro?Ustrlen(intro):0; |
| 1116 | } |
| 1117 | |
| 1118 | l += payload ? Ustrlen(payload):0 ; |
| 1119 | |
| 1120 | while (l>77) |
| 1121 | { /* this fragment will not fit on a single line */ |
| 1122 | if (pad) |
| 1123 | { |
| 1124 | str = string_catn(str, US" ", 1); |
| 1125 | *col += 1; |
| 1126 | pad = NULL; /* only want this once */ |
| 1127 | l--; |
| 1128 | } |
| 1129 | |
| 1130 | if (intro) |
| 1131 | { |
| 1132 | size_t sl = Ustrlen(intro); |
| 1133 | |
| 1134 | str = string_catn(str, intro, sl); |
| 1135 | *col += sl; |
| 1136 | l -= sl; |
| 1137 | intro = NULL; /* only want this once */ |
| 1138 | } |
| 1139 | |
| 1140 | if (payload) |
| 1141 | { |
| 1142 | size_t sl = Ustrlen(payload); |
| 1143 | size_t chomp = *col+sl < 77 ? sl : 78-*col; |
| 1144 | |
| 1145 | str = string_catn(str, payload, chomp); |
| 1146 | *col += chomp; |
| 1147 | payload += chomp; |
| 1148 | l -= chomp-1; |
| 1149 | } |
| 1150 | |
| 1151 | /* the while precondition tells us it didn't fit. */ |
| 1152 | str = pdkim_hdr_cont(str, col); |
| 1153 | } |
| 1154 | |
| 1155 | if (*col + l > 78) |
| 1156 | { |
| 1157 | str = pdkim_hdr_cont(str, col); |
| 1158 | pad = NULL; |
| 1159 | } |
| 1160 | |
| 1161 | if (pad) |
| 1162 | { |
| 1163 | str = string_catn(str, US" ", 1); |
| 1164 | *col += 1; |
| 1165 | pad = NULL; |
| 1166 | } |
| 1167 | |
| 1168 | if (intro) |
| 1169 | { |
| 1170 | size_t sl = Ustrlen(intro); |
| 1171 | |
| 1172 | str = string_catn(str, intro, sl); |
| 1173 | *col += sl; |
| 1174 | l -= sl; |
| 1175 | intro = NULL; |
| 1176 | } |
| 1177 | |
| 1178 | if (payload) |
| 1179 | { |
| 1180 | size_t sl = Ustrlen(payload); |
| 1181 | |
| 1182 | str = string_catn(str, payload, sl); |
| 1183 | *col += sl; |
| 1184 | } |
| 1185 | |
| 1186 | return str; |
| 1187 | } |
| 1188 | |
| 1189 | |
| 1190 | /* -------------------------------------------------------------------------- */ |
| 1191 | |
| 1192 | static uschar * |
| 1193 | pdkim_create_header(pdkim_signature * sig, BOOL final) |
| 1194 | { |
| 1195 | uschar * base64_bh; |
| 1196 | uschar * base64_b; |
| 1197 | int col = 0; |
| 1198 | gstring * hdr; |
| 1199 | gstring * canon_all; |
| 1200 | |
| 1201 | canon_all = string_cat (NULL, pdkim_canons[sig->canon_headers]); |
| 1202 | canon_all = string_catn(canon_all, US"/", 1); |
| 1203 | canon_all = string_cat (canon_all, pdkim_canons[sig->canon_body]); |
| 1204 | (void) string_from_gstring(canon_all); |
| 1205 | |
| 1206 | hdr = string_cat(NULL, US"DKIM-Signature: v="PDKIM_SIGNATURE_VERSION); |
| 1207 | col = hdr->ptr; |
| 1208 | |
| 1209 | /* Required and static bits */ |
| 1210 | hdr = pdkim_headcat(&col, hdr, US";", US"a=", dkim_sig_to_a_tag(sig)); |
| 1211 | hdr = pdkim_headcat(&col, hdr, US";", US"q=", pdkim_querymethods[sig->querymethod]); |
| 1212 | hdr = pdkim_headcat(&col, hdr, US";", US"c=", canon_all->s); |
| 1213 | hdr = pdkim_headcat(&col, hdr, US";", US"d=", sig->domain); |
| 1214 | hdr = pdkim_headcat(&col, hdr, US";", US"s=", sig->selector); |
| 1215 | |
| 1216 | /* list of header names can be split between items. */ |
| 1217 | { |
| 1218 | uschar * n = string_copy(sig->headernames); |
| 1219 | uschar * i = US"h="; |
| 1220 | uschar * s = US";"; |
| 1221 | |
| 1222 | while (*n) |
| 1223 | { |
| 1224 | uschar * c = Ustrchr(n, ':'); |
| 1225 | |
| 1226 | if (c) *c ='\0'; |
| 1227 | |
| 1228 | if (!i) |
| 1229 | hdr = pdkim_headcat(&col, hdr, NULL, NULL, US":"); |
| 1230 | |
| 1231 | hdr = pdkim_headcat(&col, hdr, s, i, n); |
| 1232 | |
| 1233 | if (!c) |
| 1234 | break; |
| 1235 | |
| 1236 | n = c+1; |
| 1237 | s = NULL; |
| 1238 | i = NULL; |
| 1239 | } |
| 1240 | } |
| 1241 | |
| 1242 | base64_bh = pdkim_encode_base64(&sig->bodyhash); |
| 1243 | hdr = pdkim_headcat(&col, hdr, US";", US"bh=", base64_bh); |
| 1244 | |
| 1245 | /* Optional bits */ |
| 1246 | if (sig->identity) |
| 1247 | hdr = pdkim_headcat(&col, hdr, US";", US"i=", sig->identity); |
| 1248 | |
| 1249 | if (sig->created > 0) |
| 1250 | { |
| 1251 | uschar minibuf[20]; |
| 1252 | |
| 1253 | snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->created); |
| 1254 | hdr = pdkim_headcat(&col, hdr, US";", US"t=", minibuf); |
| 1255 | } |
| 1256 | |
| 1257 | if (sig->expires > 0) |
| 1258 | { |
| 1259 | uschar minibuf[20]; |
| 1260 | |
| 1261 | snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->expires); |
| 1262 | hdr = pdkim_headcat(&col, hdr, US";", US"x=", minibuf); |
| 1263 | } |
| 1264 | |
| 1265 | if (sig->bodylength >= 0) |
| 1266 | { |
| 1267 | uschar minibuf[20]; |
| 1268 | |
| 1269 | snprintf(CS minibuf, sizeof(minibuf), "%lu", sig->bodylength); |
| 1270 | hdr = pdkim_headcat(&col, hdr, US";", US"l=", minibuf); |
| 1271 | } |
| 1272 | |
| 1273 | /* Preliminary or final version? */ |
| 1274 | if (final) |
| 1275 | { |
| 1276 | base64_b = pdkim_encode_base64(&sig->sighash); |
| 1277 | hdr = pdkim_headcat(&col, hdr, US";", US"b=", base64_b); |
| 1278 | |
| 1279 | /* add trailing semicolon: I'm not sure if this is actually needed */ |
| 1280 | hdr = pdkim_headcat(&col, hdr, NULL, US";", US""); |
| 1281 | } |
| 1282 | else |
| 1283 | { |
| 1284 | /* To satisfy the rule "all surrounding whitespace [...] deleted" |
| 1285 | ( RFC 6376 section 3.7 ) we ensure there is no whitespace here. Otherwise |
| 1286 | the headcat routine could insert a linebreak which the relaxer would reduce |
| 1287 | to a single space preceding the terminating semicolon, resulting in an |
| 1288 | incorrect header-hash. */ |
| 1289 | hdr = pdkim_headcat(&col, hdr, US";", US"b=;", US""); |
| 1290 | } |
| 1291 | |
| 1292 | return string_from_gstring(hdr); |
| 1293 | } |
| 1294 | |
| 1295 | |
| 1296 | /* -------------------------------------------------------------------------- */ |
| 1297 | |
| 1298 | static pdkim_pubkey * |
| 1299 | pdkim_key_from_dns(pdkim_ctx * ctx, pdkim_signature * sig, ev_ctx * vctx, |
| 1300 | const uschar ** errstr) |
| 1301 | { |
| 1302 | uschar * dns_txt_name, * dns_txt_reply; |
| 1303 | pdkim_pubkey * p; |
| 1304 | |
| 1305 | /* Fetch public key for signing domain, from DNS */ |
| 1306 | |
| 1307 | dns_txt_name = string_sprintf("%s._domainkey.%s.", sig->selector, sig->domain); |
| 1308 | |
| 1309 | if ( !(dns_txt_reply = ctx->dns_txt_callback(CS dns_txt_name)) |
| 1310 | || dns_txt_reply[0] == '\0' |
| 1311 | ) |
| 1312 | { |
| 1313 | sig->verify_status = PDKIM_VERIFY_INVALID; |
| 1314 | sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE; |
| 1315 | return NULL; |
| 1316 | } |
| 1317 | |
| 1318 | DEBUG(D_acl) |
| 1319 | { |
| 1320 | debug_printf( |
| 1321 | "PDKIM >> Parsing public key record >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n" |
| 1322 | " %s\n" |
| 1323 | " Raw record: ", |
| 1324 | dns_txt_name); |
| 1325 | pdkim_quoteprint(CUS dns_txt_reply, Ustrlen(dns_txt_reply)); |
| 1326 | } |
| 1327 | |
| 1328 | if ( !(p = pdkim_parse_pubkey_record(ctx, CUS dns_txt_reply)) |
| 1329 | || (Ustrcmp(p->srvtype, "*") != 0 && Ustrcmp(p->srvtype, "email") != 0) |
| 1330 | ) |
| 1331 | { |
| 1332 | sig->verify_status = PDKIM_VERIFY_INVALID; |
| 1333 | sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD; |
| 1334 | |
| 1335 | DEBUG(D_acl) |
| 1336 | { |
| 1337 | if (p) |
| 1338 | debug_printf(" Invalid public key service type '%s'\n", p->srvtype); |
| 1339 | else |
| 1340 | debug_printf(" Error while parsing public key record\n"); |
| 1341 | debug_printf( |
| 1342 | "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); |
| 1343 | } |
| 1344 | return NULL; |
| 1345 | } |
| 1346 | |
| 1347 | DEBUG(D_acl) debug_printf( |
| 1348 | "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); |
| 1349 | |
| 1350 | /* Import public key */ |
| 1351 | if ((*errstr = exim_dkim_verify_init(&p->key, vctx))) |
| 1352 | { |
| 1353 | DEBUG(D_acl) debug_printf("verify_init: %s\n", *errstr); |
| 1354 | sig->verify_status = PDKIM_VERIFY_INVALID; |
| 1355 | sig->verify_ext_status = PDKIM_VERIFY_INVALID_PUBKEY_IMPORT; |
| 1356 | return NULL; |
| 1357 | } |
| 1358 | |
| 1359 | return p; |
| 1360 | } |
| 1361 | |
| 1362 | |
| 1363 | /* -------------------------------------------------------------------------- */ |
| 1364 | |
| 1365 | DLLEXPORT int |
| 1366 | pdkim_feed_finish(pdkim_ctx * ctx, pdkim_signature ** return_signatures, |
| 1367 | const uschar ** err) |
| 1368 | { |
| 1369 | pdkim_signature * sig; |
| 1370 | |
| 1371 | /* Check if we must still flush a (partial) header. If that is the |
| 1372 | case, the message has no body, and we must compute a body hash |
| 1373 | out of '<CR><LF>' */ |
| 1374 | if (ctx->cur_header && ctx->cur_header->ptr > 0) |
| 1375 | { |
| 1376 | blob * rnl = NULL; |
| 1377 | int rc; |
| 1378 | |
| 1379 | if ((rc = pdkim_header_complete(ctx)) != PDKIM_OK) |
| 1380 | return rc; |
| 1381 | |
| 1382 | for (sig = ctx->sig; sig; sig = sig->next) |
| 1383 | rnl = pdkim_update_sig_bodyhash(sig, &lineending, rnl); |
| 1384 | if (rnl) store_free(rnl); |
| 1385 | } |
| 1386 | else |
| 1387 | DEBUG(D_acl) debug_printf( |
| 1388 | "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); |
| 1389 | |
| 1390 | /* Build (and/or evaluate) body hash */ |
| 1391 | pdkim_finish_bodyhash(ctx); |
| 1392 | |
| 1393 | for (sig = ctx->sig; sig; sig = sig->next) |
| 1394 | { |
| 1395 | hctx hhash_ctx; |
| 1396 | uschar * sig_hdr = US""; |
| 1397 | blob hhash; |
| 1398 | gstring * hdata = NULL; |
| 1399 | |
| 1400 | if (!exim_sha_init(&hhash_ctx, pdkim_hashes[sig->hashtype].exim_hashmethod)) |
| 1401 | { |
| 1402 | DEBUG(D_acl) |
| 1403 | debug_printf("PDKIM: hash setup error, possibly nonhandled hashtype\n"); |
| 1404 | break; |
| 1405 | } |
| 1406 | |
| 1407 | if (ctx->flags & PDKIM_MODE_SIGN) |
| 1408 | DEBUG(D_acl) debug_printf( |
| 1409 | "PDKIM >> Headers to be signed: >>>>>>>>>>>>\n" |
| 1410 | " %s\n", |
| 1411 | sig->sign_headers); |
| 1412 | |
| 1413 | DEBUG(D_acl) debug_printf( |
| 1414 | "PDKIM >> Header data for hash, canonicalized, in sequence >>>>>>>>>>>>\n"); |
| 1415 | |
| 1416 | |
| 1417 | /* SIGNING ---------------------------------------------------------------- */ |
| 1418 | /* When signing, walk through our header list and add them to the hash. As we |
| 1419 | go, construct a list of the header's names to use for the h= parameter. |
| 1420 | Then append to that list any remaining header names for which there was no |
| 1421 | header to sign. */ |
| 1422 | |
| 1423 | if (ctx->flags & PDKIM_MODE_SIGN) |
| 1424 | { |
| 1425 | gstring * g = NULL; |
| 1426 | pdkim_stringlist *p; |
| 1427 | const uschar * l; |
| 1428 | uschar * s; |
| 1429 | int sep = 0; |
| 1430 | |
| 1431 | sig->headernames = NULL; /* Collected signed header names */ |
| 1432 | |
| 1433 | for (p = sig->headers; p; p = p->next) |
| 1434 | { |
| 1435 | uschar * rh = p->value; |
| 1436 | |
| 1437 | if (header_name_match(rh, sig->sign_headers) == PDKIM_OK) |
| 1438 | { |
| 1439 | /* Collect header names (Note: colon presence is guaranteed here) */ |
| 1440 | g = string_append_listele_n(g, ':', rh, Ustrchr(rh, ':') - rh); |
| 1441 | |
| 1442 | if (sig->canon_headers == PDKIM_CANON_RELAXED) |
| 1443 | rh = pdkim_relax_header(rh, TRUE); /* cook header for relaxed canon */ |
| 1444 | |
| 1445 | /* Feed header to the hash algorithm */ |
| 1446 | exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh)); |
| 1447 | |
| 1448 | /* Remember headers block for signing (when the library cannot do incremental) */ |
| 1449 | hdata = exim_dkim_data_append(hdata, rh); |
| 1450 | |
| 1451 | DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh)); |
| 1452 | } |
| 1453 | } |
| 1454 | |
| 1455 | /* Any headers we wanted to sign but were not present must also be listed. |
| 1456 | Ignore elements that have been ticked-off or are marked as never-oversign. */ |
| 1457 | |
| 1458 | l = sig->sign_headers; |
| 1459 | while((s = string_nextinlist(&l, &sep, NULL, 0))) |
| 1460 | { |
| 1461 | if (*s == '+') /* skip oversigning marker */ |
| 1462 | s++; |
| 1463 | if (*s != '_' && *s != '=') |
| 1464 | g = string_append_listele(g, ':', s); |
| 1465 | } |
| 1466 | sig->headernames = string_from_gstring(g); |
| 1467 | |
| 1468 | /* Create signature header with b= omitted */ |
| 1469 | sig_hdr = pdkim_create_header(sig, FALSE); |
| 1470 | } |
| 1471 | |
| 1472 | /* VERIFICATION ----------------------------------------------------------- */ |
| 1473 | /* When verifying, walk through the header name list in the h= parameter and |
| 1474 | add the headers to the hash in that order. */ |
| 1475 | else |
| 1476 | { |
| 1477 | uschar * p = sig->headernames; |
| 1478 | uschar * q; |
| 1479 | pdkim_stringlist * hdrs; |
| 1480 | |
| 1481 | if (p) |
| 1482 | { |
| 1483 | /* clear tags */ |
| 1484 | for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next) |
| 1485 | hdrs->tag = 0; |
| 1486 | |
| 1487 | p = string_copy(p); |
| 1488 | while(1) |
| 1489 | { |
| 1490 | if ((q = Ustrchr(p, ':'))) |
| 1491 | *q = '\0'; |
| 1492 | |
| 1493 | /*XXX walk the list of headers in same order as received. */ |
| 1494 | for (hdrs = ctx->headers; hdrs; hdrs = hdrs->next) |
| 1495 | if ( hdrs->tag == 0 |
| 1496 | && strncasecmp(CCS hdrs->value, CCS p, Ustrlen(p)) == 0 |
| 1497 | && (hdrs->value)[Ustrlen(p)] == ':' |
| 1498 | ) |
| 1499 | { |
| 1500 | /* cook header for relaxed canon, or just copy it for simple */ |
| 1501 | |
| 1502 | uschar * rh = sig->canon_headers == PDKIM_CANON_RELAXED |
| 1503 | ? pdkim_relax_header(hdrs->value, TRUE) |
| 1504 | : string_copy(CUS hdrs->value); |
| 1505 | |
| 1506 | /* Feed header to the hash algorithm */ |
| 1507 | exim_sha_update(&hhash_ctx, CUS rh, Ustrlen(rh)); |
| 1508 | |
| 1509 | DEBUG(D_acl) pdkim_quoteprint(rh, Ustrlen(rh)); |
| 1510 | hdrs->tag = 1; |
| 1511 | break; |
| 1512 | } |
| 1513 | |
| 1514 | if (!q) break; |
| 1515 | p = q+1; |
| 1516 | } |
| 1517 | |
| 1518 | sig_hdr = string_copy(sig->rawsig_no_b_val); |
| 1519 | } |
| 1520 | } |
| 1521 | |
| 1522 | DEBUG(D_acl) debug_printf( |
| 1523 | "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); |
| 1524 | |
| 1525 | DEBUG(D_acl) |
| 1526 | { |
| 1527 | debug_printf( |
| 1528 | "PDKIM >> Signed DKIM-Signature header, pre-canonicalized >>>>>>>>>>>>>\n"); |
| 1529 | pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr)); |
| 1530 | debug_printf( |
| 1531 | "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); |
| 1532 | } |
| 1533 | |
| 1534 | /* Relax header if necessary */ |
| 1535 | if (sig->canon_headers == PDKIM_CANON_RELAXED) |
| 1536 | sig_hdr = pdkim_relax_header(sig_hdr, FALSE); |
| 1537 | |
| 1538 | DEBUG(D_acl) |
| 1539 | { |
| 1540 | debug_printf( |
| 1541 | "PDKIM >> Signed DKIM-Signature header, canonicalized >>>>>>>>>>>>>>>>>\n"); |
| 1542 | pdkim_quoteprint(CUS sig_hdr, Ustrlen(sig_hdr)); |
| 1543 | debug_printf( |
| 1544 | "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); |
| 1545 | } |
| 1546 | |
| 1547 | /* Finalize header hash */ |
| 1548 | exim_sha_update(&hhash_ctx, CUS sig_hdr, Ustrlen(sig_hdr)); |
| 1549 | exim_sha_finish(&hhash_ctx, &hhash); |
| 1550 | |
| 1551 | DEBUG(D_acl) |
| 1552 | { |
| 1553 | debug_printf("PDKIM [%s] Header %s computed: ", |
| 1554 | sig->domain, pdkim_hashes[sig->hashtype].dkim_hashname); |
| 1555 | pdkim_hexprint(hhash.data, hhash.len); |
| 1556 | } |
| 1557 | |
| 1558 | /* Remember headers block for signing (when the signing library cannot do |
| 1559 | incremental) */ |
| 1560 | if (ctx->flags & PDKIM_MODE_SIGN) |
| 1561 | hdata = exim_dkim_data_append(hdata, US sig_hdr); |
| 1562 | |
| 1563 | /* SIGNING ---------------------------------------------------------------- */ |
| 1564 | if (ctx->flags & PDKIM_MODE_SIGN) |
| 1565 | { |
| 1566 | es_ctx sctx; |
| 1567 | |
| 1568 | /* Import private key, including the keytype */ |
| 1569 | /*XXX extend for non-RSA algos */ |
| 1570 | if ((*err = exim_dkim_signing_init(US sig->privkey, &sctx))) |
| 1571 | { |
| 1572 | DEBUG(D_acl) debug_printf("signing_init: %s\n", *err); |
| 1573 | return PDKIM_ERR_RSA_PRIVKEY; |
| 1574 | } |
| 1575 | |
| 1576 | /* Do signing. With OpenSSL we are signing the hash of headers just |
| 1577 | calculated, with GnuTLS we have to sign an entire block of headers |
| 1578 | (due to available interfaces) and it recalculates the hash internally. */ |
| 1579 | |
| 1580 | #if defined(SIGN_GNUTLS) |
| 1581 | hhash.data = hdata->s; |
| 1582 | hhash.len = hdata->ptr; |
| 1583 | #endif |
| 1584 | |
| 1585 | /*XXX extend for non-RSA algos */ |
| 1586 | if ((*err = exim_dkim_sign(&sctx, |
| 1587 | pdkim_hashes[sig->hashtype].exim_hashmethod, |
| 1588 | &hhash, &sig->sighash))) |
| 1589 | { |
| 1590 | DEBUG(D_acl) debug_printf("signing: %s\n", *err); |
| 1591 | return PDKIM_ERR_RSA_SIGNING; |
| 1592 | } |
| 1593 | |
| 1594 | DEBUG(D_acl) |
| 1595 | { |
| 1596 | debug_printf( "PDKIM [%s] b computed: ", sig->domain); |
| 1597 | pdkim_hexprint(sig->sighash.data, sig->sighash.len); |
| 1598 | } |
| 1599 | |
| 1600 | sig->signature_header = pdkim_create_header(sig, TRUE); |
| 1601 | } |
| 1602 | |
| 1603 | /* VERIFICATION ----------------------------------------------------------- */ |
| 1604 | else |
| 1605 | { |
| 1606 | ev_ctx vctx; |
| 1607 | |
| 1608 | /* Make sure we have all required signature tags */ |
| 1609 | if (!( sig->domain && *sig->domain |
| 1610 | && sig->selector && *sig->selector |
| 1611 | && sig->headernames && *sig->headernames |
| 1612 | && sig->bodyhash.data |
| 1613 | && sig->sighash.data |
| 1614 | && sig->keytype >= 0 |
| 1615 | && sig->hashtype >= 0 |
| 1616 | && sig->version |
| 1617 | ) ) |
| 1618 | { |
| 1619 | sig->verify_status = PDKIM_VERIFY_INVALID; |
| 1620 | sig->verify_ext_status = PDKIM_VERIFY_INVALID_SIGNATURE_ERROR; |
| 1621 | |
| 1622 | DEBUG(D_acl) debug_printf( |
| 1623 | " Error in DKIM-Signature header: tags missing or invalid\n" |
| 1624 | "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); |
| 1625 | goto NEXT_VERIFY; |
| 1626 | } |
| 1627 | |
| 1628 | /* Make sure sig uses supported DKIM version (only v1) */ |
| 1629 | if (sig->version != 1) |
| 1630 | { |
| 1631 | sig->verify_status = PDKIM_VERIFY_INVALID; |
| 1632 | sig->verify_ext_status = PDKIM_VERIFY_INVALID_DKIM_VERSION; |
| 1633 | |
| 1634 | DEBUG(D_acl) debug_printf( |
| 1635 | " Error in DKIM-Signature header: unsupported DKIM version\n" |
| 1636 | "PDKIM <<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); |
| 1637 | goto NEXT_VERIFY; |
| 1638 | } |
| 1639 | |
| 1640 | DEBUG(D_acl) |
| 1641 | { |
| 1642 | debug_printf( "PDKIM [%s] b from mail: ", sig->domain); |
| 1643 | pdkim_hexprint(sig->sighash.data, sig->sighash.len); |
| 1644 | } |
| 1645 | |
| 1646 | if (!(sig->pubkey = pdkim_key_from_dns(ctx, sig, &vctx, err))) |
| 1647 | goto NEXT_VERIFY; |
| 1648 | |
| 1649 | /* If the pubkey limits to a list of specific hashes, ignore sigs that |
| 1650 | do not have the hash part of the sig algorithm matching */ |
| 1651 | |
| 1652 | if (sig->pubkey->hashes) |
| 1653 | { |
| 1654 | const uschar * list = sig->pubkey->hashes, * ele; |
| 1655 | int sep = ':'; |
| 1656 | while ((ele = string_nextinlist(&list, &sep, NULL, 0))) |
| 1657 | if (Ustrcmp(ele, pdkim_hashes[sig->hashtype].dkim_hashname) == 0) break; |
| 1658 | if (!ele) |
| 1659 | { |
| 1660 | DEBUG(D_acl) debug_printf("pubkey h=%s vs. sig a=%s_%s\n", |
| 1661 | sig->pubkey->hashes, |
| 1662 | pdkim_keytypes[sig->keytype], |
| 1663 | pdkim_hashes[sig->hashtype].dkim_hashname); |
| 1664 | sig->verify_status = PDKIM_VERIFY_FAIL; |
| 1665 | sig->verify_ext_status = PDKIM_VERIFY_FAIL_SIG_ALGO_MISMATCH; |
| 1666 | goto NEXT_VERIFY; |
| 1667 | } |
| 1668 | } |
| 1669 | |
| 1670 | /* Check the signature */ |
| 1671 | /*XXX needs extension for non-RSA */ |
| 1672 | if ((*err = exim_dkim_verify(&vctx, |
| 1673 | pdkim_hashes[sig->hashtype].exim_hashmethod, |
| 1674 | &hhash, &sig->sighash))) |
| 1675 | { |
| 1676 | DEBUG(D_acl) debug_printf("headers verify: %s\n", *err); |
| 1677 | sig->verify_status = PDKIM_VERIFY_FAIL; |
| 1678 | sig->verify_ext_status = PDKIM_VERIFY_FAIL_MESSAGE; |
| 1679 | goto NEXT_VERIFY; |
| 1680 | } |
| 1681 | |
| 1682 | |
| 1683 | /* We have a winner! (if bodyhash was correct earlier) */ |
| 1684 | if (sig->verify_status == PDKIM_VERIFY_NONE) |
| 1685 | sig->verify_status = PDKIM_VERIFY_PASS; |
| 1686 | |
| 1687 | NEXT_VERIFY: |
| 1688 | |
| 1689 | DEBUG(D_acl) |
| 1690 | { |
| 1691 | debug_printf("PDKIM [%s] signature status: %s", |
| 1692 | sig->domain, pdkim_verify_status_str(sig->verify_status)); |
| 1693 | if (sig->verify_ext_status > 0) |
| 1694 | debug_printf(" (%s)\n", |
| 1695 | pdkim_verify_ext_status_str(sig->verify_ext_status)); |
| 1696 | else |
| 1697 | debug_printf("\n"); |
| 1698 | } |
| 1699 | } |
| 1700 | } |
| 1701 | |
| 1702 | /* If requested, set return pointer to signature(s) */ |
| 1703 | if (return_signatures) |
| 1704 | *return_signatures = ctx->sig; |
| 1705 | |
| 1706 | return PDKIM_OK; |
| 1707 | } |
| 1708 | |
| 1709 | |
| 1710 | /* -------------------------------------------------------------------------- */ |
| 1711 | |
| 1712 | DLLEXPORT pdkim_ctx * |
| 1713 | pdkim_init_verify(uschar * (*dns_txt_callback)(char *), BOOL dot_stuffing) |
| 1714 | { |
| 1715 | pdkim_ctx * ctx; |
| 1716 | |
| 1717 | ctx = store_get(sizeof(pdkim_ctx)); |
| 1718 | memset(ctx, 0, sizeof(pdkim_ctx)); |
| 1719 | |
| 1720 | if (dot_stuffing) ctx->flags = PDKIM_DOT_TERM; |
| 1721 | ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN); |
| 1722 | ctx->dns_txt_callback = dns_txt_callback; |
| 1723 | |
| 1724 | return ctx; |
| 1725 | } |
| 1726 | |
| 1727 | |
| 1728 | /* -------------------------------------------------------------------------- */ |
| 1729 | |
| 1730 | /*XXX ? needs extension to cover non-RSA algo? */ |
| 1731 | |
| 1732 | DLLEXPORT pdkim_signature * |
| 1733 | pdkim_init_sign(pdkim_ctx * ctx, |
| 1734 | uschar * domain, uschar * selector, uschar * privkey, |
| 1735 | uschar * hashname, const uschar ** errstr) |
| 1736 | { |
| 1737 | int hashtype; |
| 1738 | pdkim_signature * sig; |
| 1739 | |
| 1740 | if (!domain || !selector || !privkey) |
| 1741 | return NULL; |
| 1742 | |
| 1743 | /* Allocate & init one signature struct */ |
| 1744 | |
| 1745 | sig = store_get(sizeof(pdkim_signature)); |
| 1746 | memset(sig, 0, sizeof(pdkim_signature)); |
| 1747 | |
| 1748 | sig->bodylength = -1; |
| 1749 | |
| 1750 | sig->domain = string_copy(US domain); |
| 1751 | sig->selector = string_copy(US selector); |
| 1752 | sig->privkey = string_copy(US privkey); |
| 1753 | /*XXX no keytype yet; comes from privkey */ |
| 1754 | |
| 1755 | for (hashtype = 0; hashtype < nelem(pdkim_hashes); hashtype++) |
| 1756 | if (Ustrcmp(hashname, pdkim_hashes[hashtype].dkim_hashname) == 0) |
| 1757 | { sig->hashtype = hashtype; break; } |
| 1758 | if (hashtype >= nelem(pdkim_hashes)) |
| 1759 | { |
| 1760 | DEBUG(D_acl) |
| 1761 | debug_printf("PDKIM: unrecognised hashname '%s'\n", hashname); |
| 1762 | return NULL; |
| 1763 | } |
| 1764 | |
| 1765 | if (!exim_sha_init(&sig->body_hash_ctx, pdkim_hashes[hashtype].exim_hashmethod)) |
| 1766 | { |
| 1767 | DEBUG(D_acl) |
| 1768 | debug_printf("PDKIM: hash setup error, possibly nonhandled hashtype\n"); |
| 1769 | return NULL; |
| 1770 | } |
| 1771 | |
| 1772 | DEBUG(D_acl) |
| 1773 | { |
| 1774 | pdkim_signature s = *sig; |
| 1775 | ev_ctx vctx; |
| 1776 | |
| 1777 | debug_printf("PDKIM (checking verify key)>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>\n"); |
| 1778 | if (!pdkim_key_from_dns(ctx, &s, &vctx, errstr)) |
| 1779 | debug_printf("WARNING: bad dkim key in dns\n"); |
| 1780 | debug_printf("PDKIM (finished checking verify key)<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<\n"); |
| 1781 | } |
| 1782 | return sig; |
| 1783 | } |
| 1784 | |
| 1785 | |
| 1786 | /* -------------------------------------------------------------------------- */ |
| 1787 | |
| 1788 | DLLEXPORT void |
| 1789 | pdkim_set_optional(pdkim_signature * sig, |
| 1790 | char * sign_headers, |
| 1791 | char * identity, |
| 1792 | int canon_headers, |
| 1793 | int canon_body, |
| 1794 | long bodylength, |
| 1795 | unsigned long created, |
| 1796 | unsigned long expires) |
| 1797 | { |
| 1798 | if (identity) |
| 1799 | sig->identity = string_copy(US identity); |
| 1800 | |
| 1801 | sig->sign_headers = string_copy(sign_headers |
| 1802 | ? US sign_headers : US PDKIM_DEFAULT_SIGN_HEADERS); |
| 1803 | |
| 1804 | sig->canon_headers = canon_headers; |
| 1805 | sig->canon_body = canon_body; |
| 1806 | sig->bodylength = bodylength; |
| 1807 | sig->created = created; |
| 1808 | sig->expires = expires; |
| 1809 | |
| 1810 | return; |
| 1811 | } |
| 1812 | |
| 1813 | |
| 1814 | |
| 1815 | void |
| 1816 | pdkim_init_context(pdkim_ctx * ctx, BOOL dot_stuffed, |
| 1817 | uschar * (*dns_txt_callback)(char *)) |
| 1818 | { |
| 1819 | memset(ctx, 0, sizeof(pdkim_ctx)); |
| 1820 | ctx->flags = dot_stuffed ? PDKIM_MODE_SIGN | PDKIM_DOT_TERM : PDKIM_MODE_SIGN; |
| 1821 | ctx->linebuf = store_get(PDKIM_MAX_BODY_LINE_LEN); |
| 1822 | DEBUG(D_acl) ctx->dns_txt_callback = dns_txt_callback; |
| 1823 | } |
| 1824 | |
| 1825 | |
| 1826 | void |
| 1827 | pdkim_init(void) |
| 1828 | { |
| 1829 | exim_dkim_init(); |
| 1830 | } |
| 1831 | |
| 1832 | |
| 1833 | |
| 1834 | #endif /*DISABLE_DKIM*/ |