| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* Copyright (c) University of Cambridge, 1995 - 2017 */ |
| 6 | /* See the file NOTICE for conditions of use and distribution. */ |
| 7 | |
| 8 | /* Code for DKIM support. Other DKIM relevant code is in |
| 9 | receive.c, transport.c and transports/smtp.c */ |
| 10 | |
| 11 | #include "exim.h" |
| 12 | |
| 13 | #ifndef DISABLE_DKIM |
| 14 | |
| 15 | #include "pdkim/pdkim.h" |
| 16 | |
| 17 | int dkim_verify_oldpool; |
| 18 | pdkim_ctx *dkim_verify_ctx = NULL; |
| 19 | pdkim_signature *dkim_signatures = NULL; |
| 20 | pdkim_signature *dkim_cur_sig = NULL; |
| 21 | static BOOL dkim_collect_error = FALSE; |
| 22 | |
| 23 | static int |
| 24 | dkim_exim_query_dns_txt(char *name, char *answer) |
| 25 | { |
| 26 | dns_answer dnsa; |
| 27 | dns_scan dnss; |
| 28 | dns_record *rr; |
| 29 | |
| 30 | lookup_dnssec_authenticated = NULL; |
| 31 | if (dns_lookup(&dnsa, US name, T_TXT, NULL) != DNS_SUCCEED) |
| 32 | return PDKIM_FAIL; /*XXX better error detail? logging? */ |
| 33 | |
| 34 | /* Search for TXT record */ |
| 35 | |
| 36 | for (rr = dns_next_rr(&dnsa, &dnss, RESET_ANSWERS); |
| 37 | rr; |
| 38 | rr = dns_next_rr(&dnsa, &dnss, RESET_NEXT)) |
| 39 | if (rr->type == T_TXT) |
| 40 | { |
| 41 | int rr_offset = 0; |
| 42 | int answer_offset = 0; |
| 43 | |
| 44 | /* Copy record content to the answer buffer */ |
| 45 | |
| 46 | while (rr_offset < rr->size) |
| 47 | { |
| 48 | uschar len = rr->data[rr_offset++]; |
| 49 | snprintf(answer + answer_offset, |
| 50 | PDKIM_DNS_TXT_MAX_RECLEN - answer_offset, |
| 51 | "%.*s", (int)len, (char *) (rr->data + rr_offset)); |
| 52 | rr_offset += len; |
| 53 | answer_offset += len; |
| 54 | if (answer_offset >= PDKIM_DNS_TXT_MAX_RECLEN) |
| 55 | return PDKIM_FAIL; /*XXX better error detail? logging? */ |
| 56 | } |
| 57 | return PDKIM_OK; |
| 58 | } |
| 59 | |
| 60 | return PDKIM_FAIL; /*XXX better error detail? logging? */ |
| 61 | } |
| 62 | |
| 63 | |
| 64 | void |
| 65 | dkim_exim_init(void) |
| 66 | { |
| 67 | pdkim_init(); |
| 68 | } |
| 69 | |
| 70 | |
| 71 | |
| 72 | void |
| 73 | dkim_exim_verify_init(BOOL dot_stuffing) |
| 74 | { |
| 75 | /* There is a store-reset between header & body reception |
| 76 | so cannot use the main pool. Any allocs done by Exim |
| 77 | memory-handling must use the perm pool. */ |
| 78 | |
| 79 | dkim_verify_oldpool = store_pool; |
| 80 | store_pool = POOL_PERM; |
| 81 | |
| 82 | /* Free previous context if there is one */ |
| 83 | |
| 84 | if (dkim_verify_ctx) |
| 85 | pdkim_free_ctx(dkim_verify_ctx); |
| 86 | |
| 87 | /* Create new context */ |
| 88 | |
| 89 | dkim_verify_ctx = pdkim_init_verify(&dkim_exim_query_dns_txt, dot_stuffing); |
| 90 | dkim_collect_input = !!dkim_verify_ctx; |
| 91 | dkim_collect_error = FALSE; |
| 92 | |
| 93 | /* Start feed up with any cached data */ |
| 94 | receive_get_cache(); |
| 95 | |
| 96 | store_pool = dkim_verify_oldpool; |
| 97 | } |
| 98 | |
| 99 | |
| 100 | void |
| 101 | dkim_exim_verify_feed(uschar * data, int len) |
| 102 | { |
| 103 | int rc; |
| 104 | |
| 105 | store_pool = POOL_PERM; |
| 106 | if ( dkim_collect_input |
| 107 | && (rc = pdkim_feed(dkim_verify_ctx, CS data, len)) != PDKIM_OK) |
| 108 | { |
| 109 | log_write(0, LOG_MAIN, |
| 110 | "DKIM: validation error: %.100s", pdkim_errstr(rc)); |
| 111 | dkim_collect_error = TRUE; |
| 112 | dkim_collect_input = FALSE; |
| 113 | } |
| 114 | store_pool = dkim_verify_oldpool; |
| 115 | } |
| 116 | |
| 117 | |
| 118 | void |
| 119 | dkim_exim_verify_finish(void) |
| 120 | { |
| 121 | pdkim_signature * sig = NULL; |
| 122 | int dkim_signers_size = 0; |
| 123 | int dkim_signers_ptr = 0; |
| 124 | int rc; |
| 125 | |
| 126 | store_pool = POOL_PERM; |
| 127 | |
| 128 | /* Delete eventual previous signature chain */ |
| 129 | |
| 130 | dkim_signers = NULL; |
| 131 | dkim_signatures = NULL; |
| 132 | |
| 133 | if (dkim_collect_error) |
| 134 | { |
| 135 | log_write(0, LOG_MAIN, |
| 136 | "DKIM: Error while running this message through validation," |
| 137 | " disabling signature verification."); |
| 138 | dkim_disable_verify = TRUE; |
| 139 | goto out; |
| 140 | } |
| 141 | |
| 142 | dkim_collect_input = FALSE; |
| 143 | |
| 144 | /* Finish DKIM operation and fetch link to signatures chain */ |
| 145 | |
| 146 | if ((rc = pdkim_feed_finish(dkim_verify_ctx, &dkim_signatures)) != PDKIM_OK) |
| 147 | { |
| 148 | log_write(0, LOG_MAIN, |
| 149 | "DKIM: validation error: %.100s", pdkim_errstr(rc)); |
| 150 | goto out; |
| 151 | } |
| 152 | |
| 153 | for (sig = dkim_signatures; sig; sig = sig->next) |
| 154 | { |
| 155 | int size = 0, ptr = 0; |
| 156 | uschar * logmsg = NULL, * s; |
| 157 | |
| 158 | /* Log a line for each signature */ |
| 159 | |
| 160 | if (!(s = sig->domain)) s = US"<UNSET>"; |
| 161 | logmsg = string_append(logmsg, &size, &ptr, 2, "d=", s); |
| 162 | if (!(s = sig->selector)) s = US"<UNSET>"; |
| 163 | logmsg = string_append(logmsg, &size, &ptr, 2, " s=", s); |
| 164 | logmsg = string_append(logmsg, &size, &ptr, 7, |
| 165 | " c=", sig->canon_headers == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", |
| 166 | "/", sig->canon_body == PDKIM_CANON_SIMPLE ? "simple" : "relaxed", |
| 167 | " a=", sig->algo == PDKIM_ALGO_RSA_SHA256 |
| 168 | ? "rsa-sha256" |
| 169 | : sig->algo == PDKIM_ALGO_RSA_SHA1 ? "rsa-sha1" : "err", |
| 170 | string_sprintf(" b=%d", |
| 171 | (int)sig->sighash.len > -1 ? sig->sighash.len * 8 : 0)); |
| 172 | if ((s= sig->identity)) string_append(logmsg, &size, &ptr, 2, " i=", s); |
| 173 | if (sig->created > 0) string_append(logmsg, &size, &ptr, 1, |
| 174 | string_sprintf(" t=%lu", sig->created)); |
| 175 | if (sig->expires > 0) string_append(logmsg, &size, &ptr, 1, |
| 176 | string_sprintf(" x=%lu", sig->expires)); |
| 177 | if (sig->bodylength > -1) string_append(logmsg, &size, &ptr, 1, |
| 178 | string_sprintf(" l=%lu", sig->bodylength)); |
| 179 | |
| 180 | switch (sig->verify_status) |
| 181 | { |
| 182 | case PDKIM_VERIFY_NONE: |
| 183 | logmsg = string_append(logmsg, &size, &ptr, 1, " [not verified]"); |
| 184 | break; |
| 185 | |
| 186 | case PDKIM_VERIFY_INVALID: |
| 187 | logmsg = string_append(logmsg, &size, &ptr, 1, " [invalid - "); |
| 188 | switch (sig->verify_ext_status) |
| 189 | { |
| 190 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: |
| 191 | logmsg = string_append(logmsg, &size, &ptr, 1, |
| 192 | "public key record (currently?) unavailable]"); |
| 193 | break; |
| 194 | |
| 195 | case PDKIM_VERIFY_INVALID_BUFFER_SIZE: |
| 196 | logmsg = string_append(logmsg, &size, &ptr, 1, |
| 197 | "overlong public key record]"); |
| 198 | break; |
| 199 | |
| 200 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD: |
| 201 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: |
| 202 | logmsg = string_append(logmsg, &size, &ptr, 1, |
| 203 | "syntax error in public key record]"); |
| 204 | break; |
| 205 | |
| 206 | case PDKIM_VERIFY_INVALID_SIGNATURE_ERROR: |
| 207 | logmsg = string_append(logmsg, &size, &ptr, 1, |
| 208 | "signature tag missing or invalid]"); |
| 209 | break; |
| 210 | |
| 211 | case PDKIM_VERIFY_INVALID_DKIM_VERSION: |
| 212 | logmsg = string_append(logmsg, &size, &ptr, 1, |
| 213 | "unsupported DKIM version]"); |
| 214 | break; |
| 215 | |
| 216 | default: |
| 217 | logmsg = string_append(logmsg, &size, &ptr, 1, |
| 218 | "unspecified problem]"); |
| 219 | } |
| 220 | break; |
| 221 | |
| 222 | case PDKIM_VERIFY_FAIL: |
| 223 | logmsg = |
| 224 | string_append(logmsg, &size, &ptr, 1, " [verification failed - "); |
| 225 | switch (sig->verify_ext_status) |
| 226 | { |
| 227 | case PDKIM_VERIFY_FAIL_BODY: |
| 228 | logmsg = string_append(logmsg, &size, &ptr, 1, |
| 229 | "body hash mismatch (body probably modified in transit)]"); |
| 230 | break; |
| 231 | |
| 232 | case PDKIM_VERIFY_FAIL_MESSAGE: |
| 233 | logmsg = string_append(logmsg, &size, &ptr, 1, |
| 234 | "signature did not verify (headers probably modified in transit)]"); |
| 235 | break; |
| 236 | |
| 237 | default: |
| 238 | logmsg = string_append(logmsg, &size, &ptr, 1, "unspecified reason]"); |
| 239 | } |
| 240 | break; |
| 241 | |
| 242 | case PDKIM_VERIFY_PASS: |
| 243 | logmsg = |
| 244 | string_append(logmsg, &size, &ptr, 1, " [verification succeeded]"); |
| 245 | break; |
| 246 | } |
| 247 | |
| 248 | logmsg[ptr] = '\0'; |
| 249 | log_write(0, LOG_MAIN, "DKIM: %s", logmsg); |
| 250 | |
| 251 | /* Build a colon-separated list of signing domains (and identities, if present) in dkim_signers */ |
| 252 | |
| 253 | if (sig->domain) |
| 254 | dkim_signers = string_append_listele(dkim_signers, ':', sig->domain); |
| 255 | |
| 256 | if (sig->identity) |
| 257 | dkim_signers = string_append_listele(dkim_signers, ':', sig->identity); |
| 258 | |
| 259 | /* Process next signature */ |
| 260 | } |
| 261 | |
| 262 | out: |
| 263 | store_pool = dkim_verify_oldpool; |
| 264 | } |
| 265 | |
| 266 | |
| 267 | void |
| 268 | dkim_exim_acl_setup(uschar * id) |
| 269 | { |
| 270 | pdkim_signature * sig; |
| 271 | uschar * cmp_val; |
| 272 | |
| 273 | dkim_cur_sig = NULL; |
| 274 | dkim_cur_signer = id; |
| 275 | |
| 276 | if (dkim_disable_verify || !id || !dkim_verify_ctx) |
| 277 | return; |
| 278 | |
| 279 | /* Find signature to run ACL on */ |
| 280 | |
| 281 | for (sig = dkim_signatures; sig; sig = sig->next) |
| 282 | if ( (cmp_val = Ustrchr(id, '@') != NULL ? US sig->identity : US sig->domain) |
| 283 | && strcmpic(cmp_val, id) == 0 |
| 284 | ) |
| 285 | { |
| 286 | dkim_cur_sig = sig; |
| 287 | |
| 288 | /* The "dkim_domain" and "dkim_selector" expansion variables have |
| 289 | related globals, since they are used in the signing code too. |
| 290 | Instead of inventing separate names for verification, we set |
| 291 | them here. This is easy since a domain and selector is guaranteed |
| 292 | to be in a signature. The other dkim_* expansion items are |
| 293 | dynamically fetched from dkim_cur_sig at expansion time (see |
| 294 | function below). */ |
| 295 | |
| 296 | dkim_signing_domain = US sig->domain; |
| 297 | dkim_signing_selector = US sig->selector; |
| 298 | dkim_key_length = sig->sighash.len * 8; |
| 299 | return; |
| 300 | } |
| 301 | } |
| 302 | |
| 303 | |
| 304 | static uschar * |
| 305 | dkim_exim_expand_defaults(int what) |
| 306 | { |
| 307 | switch (what) |
| 308 | { |
| 309 | case DKIM_ALGO: return US""; |
| 310 | case DKIM_BODYLENGTH: return US"9999999999999"; |
| 311 | case DKIM_CANON_BODY: return US""; |
| 312 | case DKIM_CANON_HEADERS: return US""; |
| 313 | case DKIM_COPIEDHEADERS: return US""; |
| 314 | case DKIM_CREATED: return US"0"; |
| 315 | case DKIM_EXPIRES: return US"9999999999999"; |
| 316 | case DKIM_HEADERNAMES: return US""; |
| 317 | case DKIM_IDENTITY: return US""; |
| 318 | case DKIM_KEY_GRANULARITY: return US"*"; |
| 319 | case DKIM_KEY_SRVTYPE: return US"*"; |
| 320 | case DKIM_KEY_NOTES: return US""; |
| 321 | case DKIM_KEY_TESTING: return US"0"; |
| 322 | case DKIM_NOSUBDOMAINS: return US"0"; |
| 323 | case DKIM_VERIFY_STATUS: return US"none"; |
| 324 | case DKIM_VERIFY_REASON: return US""; |
| 325 | default: return US""; |
| 326 | } |
| 327 | } |
| 328 | |
| 329 | |
| 330 | uschar * |
| 331 | dkim_exim_expand_query(int what) |
| 332 | { |
| 333 | if (!dkim_verify_ctx || dkim_disable_verify || !dkim_cur_sig) |
| 334 | return dkim_exim_expand_defaults(what); |
| 335 | |
| 336 | switch (what) |
| 337 | { |
| 338 | case DKIM_ALGO: |
| 339 | switch (dkim_cur_sig->algo) |
| 340 | { |
| 341 | case PDKIM_ALGO_RSA_SHA1: return US"rsa-sha1"; |
| 342 | case PDKIM_ALGO_RSA_SHA256: |
| 343 | default: return US"rsa-sha256"; |
| 344 | } |
| 345 | |
| 346 | case DKIM_BODYLENGTH: |
| 347 | return dkim_cur_sig->bodylength >= 0 |
| 348 | ? string_sprintf(OFF_T_FMT, (LONGLONG_T) dkim_cur_sig->bodylength) |
| 349 | : dkim_exim_expand_defaults(what); |
| 350 | |
| 351 | case DKIM_CANON_BODY: |
| 352 | switch (dkim_cur_sig->canon_body) |
| 353 | { |
| 354 | case PDKIM_CANON_RELAXED: return US"relaxed"; |
| 355 | case PDKIM_CANON_SIMPLE: |
| 356 | default: return US"simple"; |
| 357 | } |
| 358 | |
| 359 | case DKIM_CANON_HEADERS: |
| 360 | switch (dkim_cur_sig->canon_headers) |
| 361 | { |
| 362 | case PDKIM_CANON_RELAXED: return US"relaxed"; |
| 363 | case PDKIM_CANON_SIMPLE: |
| 364 | default: return US"simple"; |
| 365 | } |
| 366 | |
| 367 | case DKIM_COPIEDHEADERS: |
| 368 | return dkim_cur_sig->copiedheaders |
| 369 | ? US dkim_cur_sig->copiedheaders : dkim_exim_expand_defaults(what); |
| 370 | |
| 371 | case DKIM_CREATED: |
| 372 | return dkim_cur_sig->created > 0 |
| 373 | ? string_sprintf("%llu", dkim_cur_sig->created) |
| 374 | : dkim_exim_expand_defaults(what); |
| 375 | |
| 376 | case DKIM_EXPIRES: |
| 377 | return dkim_cur_sig->expires > 0 |
| 378 | ? string_sprintf("%llu", dkim_cur_sig->expires) |
| 379 | : dkim_exim_expand_defaults(what); |
| 380 | |
| 381 | case DKIM_HEADERNAMES: |
| 382 | return dkim_cur_sig->headernames |
| 383 | ? dkim_cur_sig->headernames : dkim_exim_expand_defaults(what); |
| 384 | |
| 385 | case DKIM_IDENTITY: |
| 386 | return dkim_cur_sig->identity |
| 387 | ? US dkim_cur_sig->identity : dkim_exim_expand_defaults(what); |
| 388 | |
| 389 | case DKIM_KEY_GRANULARITY: |
| 390 | return dkim_cur_sig->pubkey |
| 391 | ? dkim_cur_sig->pubkey->granularity |
| 392 | ? US dkim_cur_sig->pubkey->granularity |
| 393 | : dkim_exim_expand_defaults(what) |
| 394 | : dkim_exim_expand_defaults(what); |
| 395 | |
| 396 | case DKIM_KEY_SRVTYPE: |
| 397 | return dkim_cur_sig->pubkey |
| 398 | ? dkim_cur_sig->pubkey->srvtype |
| 399 | ? US dkim_cur_sig->pubkey->srvtype |
| 400 | : dkim_exim_expand_defaults(what) |
| 401 | : dkim_exim_expand_defaults(what); |
| 402 | |
| 403 | case DKIM_KEY_NOTES: |
| 404 | return dkim_cur_sig->pubkey |
| 405 | ? dkim_cur_sig->pubkey->notes |
| 406 | ? US dkim_cur_sig->pubkey->notes |
| 407 | : dkim_exim_expand_defaults(what) |
| 408 | : dkim_exim_expand_defaults(what); |
| 409 | |
| 410 | case DKIM_KEY_TESTING: |
| 411 | return dkim_cur_sig->pubkey |
| 412 | ? dkim_cur_sig->pubkey->testing |
| 413 | ? US"1" |
| 414 | : dkim_exim_expand_defaults(what) |
| 415 | : dkim_exim_expand_defaults(what); |
| 416 | |
| 417 | case DKIM_NOSUBDOMAINS: |
| 418 | return dkim_cur_sig->pubkey |
| 419 | ? dkim_cur_sig->pubkey->no_subdomaining |
| 420 | ? US"1" |
| 421 | : dkim_exim_expand_defaults(what) |
| 422 | : dkim_exim_expand_defaults(what); |
| 423 | |
| 424 | case DKIM_VERIFY_STATUS: |
| 425 | switch (dkim_cur_sig->verify_status) |
| 426 | { |
| 427 | case PDKIM_VERIFY_INVALID: return US"invalid"; |
| 428 | case PDKIM_VERIFY_FAIL: return US"fail"; |
| 429 | case PDKIM_VERIFY_PASS: return US"pass"; |
| 430 | case PDKIM_VERIFY_NONE: |
| 431 | default: return US"none"; |
| 432 | } |
| 433 | |
| 434 | case DKIM_VERIFY_REASON: |
| 435 | switch (dkim_cur_sig->verify_ext_status) |
| 436 | { |
| 437 | case PDKIM_VERIFY_INVALID_PUBKEY_UNAVAILABLE: |
| 438 | return US"pubkey_unavailable"; |
| 439 | case PDKIM_VERIFY_INVALID_PUBKEY_DNSRECORD:return US"pubkey_dns_syntax"; |
| 440 | case PDKIM_VERIFY_INVALID_PUBKEY_IMPORT: return US"pubkey_der_syntax"; |
| 441 | case PDKIM_VERIFY_FAIL_BODY: return US"bodyhash_mismatch"; |
| 442 | case PDKIM_VERIFY_FAIL_MESSAGE: return US"signature_incorrect"; |
| 443 | } |
| 444 | |
| 445 | default: |
| 446 | return US""; |
| 447 | } |
| 448 | } |
| 449 | |
| 450 | |
| 451 | uschar * |
| 452 | dkim_exim_sign(int dkim_fd, struct ob_dkim * dkim) |
| 453 | { |
| 454 | const uschar * dkim_domain; |
| 455 | int sep = 0; |
| 456 | uschar *seen_items = NULL; |
| 457 | int seen_items_size = 0; |
| 458 | int seen_items_offset = 0; |
| 459 | uschar itembuf[256]; |
| 460 | uschar *dkim_canon_expanded; |
| 461 | uschar *dkim_sign_headers_expanded; |
| 462 | uschar *dkim_private_key_expanded; |
| 463 | pdkim_ctx *ctx = NULL; |
| 464 | uschar *rc = NULL; |
| 465 | uschar *sigbuf = NULL; |
| 466 | int sigsize = 0; |
| 467 | int sigptr = 0; |
| 468 | pdkim_signature *signature; |
| 469 | int pdkim_canon; |
| 470 | int pdkim_rc; |
| 471 | int sread; |
| 472 | char buf[4096]; |
| 473 | int save_errno = 0; |
| 474 | int old_pool = store_pool; |
| 475 | |
| 476 | store_pool = POOL_MAIN; |
| 477 | |
| 478 | if (!(dkim_domain = expand_cstring(dkim->dkim_domain))) |
| 479 | { |
| 480 | /* expansion error, do not send message. */ |
| 481 | log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " |
| 482 | "dkim_domain: %s", expand_string_message); |
| 483 | goto bad; |
| 484 | } |
| 485 | |
| 486 | /* Set $dkim_domain expansion variable to each unique domain in list. */ |
| 487 | |
| 488 | while ((dkim_signing_domain = string_nextinlist(&dkim_domain, &sep, |
| 489 | itembuf, sizeof(itembuf)))) |
| 490 | { |
| 491 | if (!dkim_signing_domain || dkim_signing_domain[0] == '\0') |
| 492 | continue; |
| 493 | |
| 494 | /* Only sign once for each domain, no matter how often it |
| 495 | appears in the expanded list. */ |
| 496 | |
| 497 | if (seen_items) |
| 498 | { |
| 499 | const uschar *seen_items_list = seen_items; |
| 500 | if (match_isinlist(dkim_signing_domain, |
| 501 | &seen_items_list, 0, NULL, NULL, MCL_STRING, TRUE, |
| 502 | NULL) == OK) |
| 503 | continue; |
| 504 | |
| 505 | seen_items = |
| 506 | string_append(seen_items, &seen_items_size, &seen_items_offset, 1, ":"); |
| 507 | } |
| 508 | |
| 509 | seen_items = |
| 510 | string_append(seen_items, &seen_items_size, &seen_items_offset, 1, |
| 511 | dkim_signing_domain); |
| 512 | seen_items[seen_items_offset] = '\0'; |
| 513 | |
| 514 | /* Set up $dkim_selector expansion variable. */ |
| 515 | |
| 516 | if (!(dkim_signing_selector = expand_string(dkim->dkim_selector))) |
| 517 | { |
| 518 | log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " |
| 519 | "dkim_selector: %s", expand_string_message); |
| 520 | goto bad; |
| 521 | } |
| 522 | |
| 523 | /* Get canonicalization to use */ |
| 524 | |
| 525 | dkim_canon_expanded = dkim->dkim_canon |
| 526 | ? expand_string(dkim->dkim_canon) : US"relaxed"; |
| 527 | if (!dkim_canon_expanded) |
| 528 | { |
| 529 | /* expansion error, do not send message. */ |
| 530 | log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " |
| 531 | "dkim_canon: %s", expand_string_message); |
| 532 | goto bad; |
| 533 | } |
| 534 | |
| 535 | if (Ustrcmp(dkim_canon_expanded, "relaxed") == 0) |
| 536 | pdkim_canon = PDKIM_CANON_RELAXED; |
| 537 | else if (Ustrcmp(dkim_canon_expanded, "simple") == 0) |
| 538 | pdkim_canon = PDKIM_CANON_SIMPLE; |
| 539 | else |
| 540 | { |
| 541 | log_write(0, LOG_MAIN, |
| 542 | "DKIM: unknown canonicalization method '%s', defaulting to 'relaxed'.\n", |
| 543 | dkim_canon_expanded); |
| 544 | pdkim_canon = PDKIM_CANON_RELAXED; |
| 545 | } |
| 546 | |
| 547 | dkim_sign_headers_expanded = NULL; |
| 548 | if (dkim->dkim_sign_headers) |
| 549 | if (!(dkim_sign_headers_expanded = expand_string(dkim->dkim_sign_headers))) |
| 550 | { |
| 551 | log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " |
| 552 | "dkim_sign_headers: %s", expand_string_message); |
| 553 | goto bad; |
| 554 | } |
| 555 | /* else pass NULL, which means default header list */ |
| 556 | |
| 557 | /* Get private key to use. */ |
| 558 | |
| 559 | if (!(dkim_private_key_expanded = expand_string(dkim->dkim_private_key))) |
| 560 | { |
| 561 | log_write(0, LOG_MAIN | LOG_PANIC, "failed to expand " |
| 562 | "dkim_private_key: %s", expand_string_message); |
| 563 | goto bad; |
| 564 | } |
| 565 | |
| 566 | if ( Ustrlen(dkim_private_key_expanded) == 0 |
| 567 | || Ustrcmp(dkim_private_key_expanded, "0") == 0 |
| 568 | || Ustrcmp(dkim_private_key_expanded, "false") == 0 |
| 569 | ) |
| 570 | continue; /* don't sign, but no error */ |
| 571 | |
| 572 | if (dkim_private_key_expanded[0] == '/') |
| 573 | { |
| 574 | int privkey_fd, off = 0, len; |
| 575 | |
| 576 | /* Looks like a filename, load the private key. */ |
| 577 | |
| 578 | memset(big_buffer, 0, big_buffer_size); |
| 579 | |
| 580 | if ((privkey_fd = open(CS dkim_private_key_expanded, O_RDONLY)) < 0) |
| 581 | { |
| 582 | log_write(0, LOG_MAIN | LOG_PANIC, "unable to open " |
| 583 | "private key file for reading: %s", |
| 584 | dkim_private_key_expanded); |
| 585 | goto bad; |
| 586 | } |
| 587 | |
| 588 | do |
| 589 | { |
| 590 | if ((len = read(privkey_fd, big_buffer + off, big_buffer_size - 2 - off)) < 0) |
| 591 | { |
| 592 | (void) close(privkey_fd); |
| 593 | log_write(0, LOG_MAIN|LOG_PANIC, "unable to read private key file: %s", |
| 594 | dkim_private_key_expanded); |
| 595 | goto bad; |
| 596 | } |
| 597 | off += len; |
| 598 | } |
| 599 | while (len > 0); |
| 600 | |
| 601 | (void) close(privkey_fd); |
| 602 | big_buffer[off] = '\0'; |
| 603 | dkim_private_key_expanded = big_buffer; |
| 604 | } |
| 605 | |
| 606 | ctx = pdkim_init_sign(CS dkim_signing_domain, |
| 607 | CS dkim_signing_selector, |
| 608 | CS dkim_private_key_expanded, |
| 609 | PDKIM_ALGO_RSA_SHA256, |
| 610 | dkim->dot_stuffed, |
| 611 | &dkim_exim_query_dns_txt |
| 612 | ); |
| 613 | dkim_private_key_expanded[0] = '\0'; |
| 614 | pdkim_set_optional(ctx, |
| 615 | CS dkim_sign_headers_expanded, |
| 616 | NULL, |
| 617 | pdkim_canon, |
| 618 | pdkim_canon, -1, 0, 0); |
| 619 | |
| 620 | lseek(dkim_fd, 0, SEEK_SET); |
| 621 | |
| 622 | while ((sread = read(dkim_fd, &buf, sizeof(buf))) > 0) |
| 623 | if ((pdkim_rc = pdkim_feed(ctx, buf, sread)) != PDKIM_OK) |
| 624 | goto pk_bad; |
| 625 | |
| 626 | /* Handle failed read above. */ |
| 627 | if (sread == -1) |
| 628 | { |
| 629 | debug_printf("DKIM: Error reading -K file.\n"); |
| 630 | save_errno = errno; |
| 631 | goto bad; |
| 632 | } |
| 633 | |
| 634 | if ((pdkim_rc = pdkim_feed_finish(ctx, &signature)) != PDKIM_OK) |
| 635 | goto pk_bad; |
| 636 | |
| 637 | sigbuf = string_append(sigbuf, &sigsize, &sigptr, 2, |
| 638 | US signature->signature_header, US"\r\n"); |
| 639 | |
| 640 | pdkim_free_ctx(ctx); |
| 641 | ctx = NULL; |
| 642 | } |
| 643 | |
| 644 | if (sigbuf) |
| 645 | { |
| 646 | sigbuf[sigptr] = '\0'; |
| 647 | rc = sigbuf; |
| 648 | } |
| 649 | else |
| 650 | rc = US""; |
| 651 | |
| 652 | CLEANUP: |
| 653 | if (ctx) |
| 654 | pdkim_free_ctx(ctx); |
| 655 | store_pool = old_pool; |
| 656 | errno = save_errno; |
| 657 | return rc; |
| 658 | |
| 659 | pk_bad: |
| 660 | log_write(0, LOG_MAIN|LOG_PANIC, |
| 661 | "DKIM: signing failed: %.100s", pdkim_errstr(pdkim_rc)); |
| 662 | bad: |
| 663 | rc = NULL; |
| 664 | goto CLEANUP; |
| 665 | } |
| 666 | |
| 667 | #endif |