| 1 | /************************************************* |
| 2 | * Exim - an Internet mail transport agent * |
| 3 | *************************************************/ |
| 4 | |
| 5 | /* Copyright (c) Jeremy Harris 2014 - 2018 */ |
| 6 | |
| 7 | /* This file provides TLS/SSL support for Exim using the GnuTLS library, |
| 8 | one of the available supported implementations. This file is #included into |
| 9 | tls.c when USE_GNUTLS has been set. |
| 10 | */ |
| 11 | |
| 12 | #include <gnutls/gnutls.h> |
| 13 | /* needed for cert checks in verification and DN extraction: */ |
| 14 | #include <gnutls/x509.h> |
| 15 | /* needed to disable PKCS11 autoload unless requested */ |
| 16 | #if GNUTLS_VERSION_NUMBER >= 0x020c00 |
| 17 | # include <gnutls/pkcs11.h> |
| 18 | #endif |
| 19 | |
| 20 | |
| 21 | /***************************************************** |
| 22 | * Export/import a certificate, binary/printable |
| 23 | *****************************************************/ |
| 24 | int |
| 25 | tls_export_cert(uschar * buf, size_t buflen, void * cert) |
| 26 | { |
| 27 | size_t sz = buflen; |
| 28 | void * reset_point = store_get(0); |
| 29 | int fail; |
| 30 | const uschar * cp; |
| 31 | |
| 32 | if ((fail = gnutls_x509_crt_export((gnutls_x509_crt_t)cert, |
| 33 | GNUTLS_X509_FMT_PEM, buf, &sz))) |
| 34 | { |
| 35 | log_write(0, LOG_MAIN, "TLS error in certificate export: %s", |
| 36 | gnutls_strerror(fail)); |
| 37 | return 1; |
| 38 | } |
| 39 | if ((cp = string_printing(buf)) != buf) |
| 40 | { |
| 41 | Ustrncpy(buf, cp, buflen); |
| 42 | if (buf[buflen-1]) |
| 43 | fail = 1; |
| 44 | } |
| 45 | store_reset(reset_point); |
| 46 | return fail; |
| 47 | } |
| 48 | |
| 49 | int |
| 50 | tls_import_cert(const uschar * buf, void ** cert) |
| 51 | { |
| 52 | void * reset_point = store_get(0); |
| 53 | gnutls_datum_t datum; |
| 54 | gnutls_x509_crt_t crt = *(gnutls_x509_crt_t *)cert; |
| 55 | int fail = 0; |
| 56 | |
| 57 | if (crt) |
| 58 | gnutls_x509_crt_deinit(crt); |
| 59 | else |
| 60 | gnutls_global_init(); |
| 61 | |
| 62 | gnutls_x509_crt_init(&crt); |
| 63 | |
| 64 | datum.data = string_unprinting(US buf); |
| 65 | datum.size = Ustrlen(datum.data); |
| 66 | if ((fail = gnutls_x509_crt_import(crt, &datum, GNUTLS_X509_FMT_PEM))) |
| 67 | { |
| 68 | log_write(0, LOG_MAIN, "TLS error in certificate import: %s", |
| 69 | gnutls_strerror(fail)); |
| 70 | fail = 1; |
| 71 | } |
| 72 | else |
| 73 | *cert = (void *)crt; |
| 74 | |
| 75 | store_reset(reset_point); |
| 76 | return fail; |
| 77 | } |
| 78 | |
| 79 | void |
| 80 | tls_free_cert(void ** cert) |
| 81 | { |
| 82 | gnutls_x509_crt_t crt = *(gnutls_x509_crt_t *)cert; |
| 83 | if (crt) |
| 84 | { |
| 85 | gnutls_x509_crt_deinit(crt); |
| 86 | gnutls_global_deinit(); |
| 87 | *cert = NULL; |
| 88 | } |
| 89 | } |
| 90 | |
| 91 | /***************************************************** |
| 92 | * Certificate field extraction routines |
| 93 | *****************************************************/ |
| 94 | |
| 95 | /* First, some internal service functions */ |
| 96 | |
| 97 | static uschar * |
| 98 | g_err(const char * tag, const char * from, int gnutls_err) |
| 99 | { |
| 100 | expand_string_message = string_sprintf("%s: %s fail: %s\n", |
| 101 | from, tag, gnutls_strerror(gnutls_err)); |
| 102 | return NULL; |
| 103 | } |
| 104 | |
| 105 | |
| 106 | static uschar * |
| 107 | time_copy(time_t t, uschar * mod) |
| 108 | { |
| 109 | uschar * cp; |
| 110 | size_t len = 32; |
| 111 | |
| 112 | if (mod && Ustrcmp(mod, "int") == 0) |
| 113 | return string_sprintf("%u", (unsigned)t); |
| 114 | |
| 115 | cp = store_get(len); |
| 116 | if (f.timestamps_utc) |
| 117 | { |
| 118 | uschar * tz = to_tz(US"GMT0"); |
| 119 | len = strftime(CS cp, len, "%b %e %T %Y %Z", gmtime(&t)); |
| 120 | restore_tz(tz); |
| 121 | } |
| 122 | else |
| 123 | len = strftime(CS cp, len, "%b %e %T %Y %Z", localtime(&t)); |
| 124 | return len > 0 ? cp : NULL; |
| 125 | } |
| 126 | |
| 127 | |
| 128 | /**/ |
| 129 | /* Now the extractors, called from expand.c |
| 130 | Arguments: |
| 131 | cert The certificate |
| 132 | mod Optional modifiers for the operator |
| 133 | |
| 134 | Return: |
| 135 | Allocated string with extracted value |
| 136 | */ |
| 137 | |
| 138 | uschar * |
| 139 | tls_cert_issuer(void * cert, uschar * mod) |
| 140 | { |
| 141 | uschar * cp = NULL; |
| 142 | int ret; |
| 143 | size_t siz = 0; |
| 144 | |
| 145 | if ((ret = gnutls_x509_crt_get_issuer_dn(cert, CS cp, &siz)) |
| 146 | != GNUTLS_E_SHORT_MEMORY_BUFFER) |
| 147 | return g_err("gi0", __FUNCTION__, ret); |
| 148 | |
| 149 | cp = store_get(siz); |
| 150 | if ((ret = gnutls_x509_crt_get_issuer_dn(cert, CS cp, &siz)) < 0) |
| 151 | return g_err("gi1", __FUNCTION__, ret); |
| 152 | |
| 153 | return mod ? tls_field_from_dn(cp, mod) : cp; |
| 154 | } |
| 155 | |
| 156 | uschar * |
| 157 | tls_cert_not_after(void * cert, uschar * mod) |
| 158 | { |
| 159 | return time_copy( |
| 160 | gnutls_x509_crt_get_expiration_time((gnutls_x509_crt_t)cert), |
| 161 | mod); |
| 162 | } |
| 163 | |
| 164 | uschar * |
| 165 | tls_cert_not_before(void * cert, uschar * mod) |
| 166 | { |
| 167 | return time_copy( |
| 168 | gnutls_x509_crt_get_activation_time((gnutls_x509_crt_t)cert), |
| 169 | mod); |
| 170 | } |
| 171 | |
| 172 | uschar * |
| 173 | tls_cert_serial_number(void * cert, uschar * mod) |
| 174 | { |
| 175 | uschar bin[50], txt[150]; |
| 176 | uschar * sp = bin; |
| 177 | size_t sz = sizeof(bin); |
| 178 | int ret; |
| 179 | |
| 180 | if ((ret = gnutls_x509_crt_get_serial((gnutls_x509_crt_t)cert, |
| 181 | bin, &sz))) |
| 182 | return g_err("gs0", __FUNCTION__, ret); |
| 183 | |
| 184 | for(uschar * dp = txt; sz; sz--) |
| 185 | dp += sprintf(CS dp, "%.2x", *sp++); |
| 186 | for(sp = txt; sp[0]=='0' && sp[1]; ) sp++; /* leading zeroes */ |
| 187 | return string_copy(sp); |
| 188 | } |
| 189 | |
| 190 | uschar * |
| 191 | tls_cert_signature(void * cert, uschar * mod) |
| 192 | { |
| 193 | uschar * cp1 = NULL; |
| 194 | uschar * cp2; |
| 195 | uschar * cp3; |
| 196 | size_t len = 0; |
| 197 | int ret; |
| 198 | |
| 199 | if ((ret = gnutls_x509_crt_get_signature((gnutls_x509_crt_t)cert, CS cp1, &len)) |
| 200 | != GNUTLS_E_SHORT_MEMORY_BUFFER) |
| 201 | return g_err("gs0", __FUNCTION__, ret); |
| 202 | |
| 203 | cp1 = store_get(len*4+1); |
| 204 | if (gnutls_x509_crt_get_signature((gnutls_x509_crt_t)cert, CS cp1, &len) != 0) |
| 205 | return g_err("gs1", __FUNCTION__, ret); |
| 206 | |
| 207 | for(cp3 = cp2 = cp1+len; cp1 < cp2; cp1++) |
| 208 | cp3 += sprintf(CS cp3, "%.2x ", *cp1); |
| 209 | cp3[-1]= '\0'; |
| 210 | |
| 211 | return cp2; |
| 212 | } |
| 213 | |
| 214 | uschar * |
| 215 | tls_cert_signature_algorithm(void * cert, uschar * mod) |
| 216 | { |
| 217 | gnutls_sign_algorithm_t algo = |
| 218 | gnutls_x509_crt_get_signature_algorithm((gnutls_x509_crt_t)cert); |
| 219 | return algo < 0 ? NULL : string_copy(US gnutls_sign_get_name(algo)); |
| 220 | } |
| 221 | |
| 222 | uschar * |
| 223 | tls_cert_subject(void * cert, uschar * mod) |
| 224 | { |
| 225 | uschar * cp = NULL; |
| 226 | int ret; |
| 227 | size_t siz = 0; |
| 228 | |
| 229 | if ((ret = gnutls_x509_crt_get_dn(cert, CS cp, &siz)) |
| 230 | != GNUTLS_E_SHORT_MEMORY_BUFFER) |
| 231 | return g_err("gs0", __FUNCTION__, ret); |
| 232 | |
| 233 | cp = store_get(siz); |
| 234 | if ((ret = gnutls_x509_crt_get_dn(cert, CS cp, &siz)) < 0) |
| 235 | return g_err("gs1", __FUNCTION__, ret); |
| 236 | |
| 237 | return mod ? tls_field_from_dn(cp, mod) : cp; |
| 238 | } |
| 239 | |
| 240 | uschar * |
| 241 | tls_cert_version(void * cert, uschar * mod) |
| 242 | { |
| 243 | return string_sprintf("%d", gnutls_x509_crt_get_version(cert)); |
| 244 | } |
| 245 | |
| 246 | uschar * |
| 247 | tls_cert_ext_by_oid(void * cert, uschar * oid, int idx) |
| 248 | { |
| 249 | uschar * cp1 = NULL; |
| 250 | uschar * cp2; |
| 251 | uschar * cp3; |
| 252 | size_t siz = 0; |
| 253 | unsigned int crit; |
| 254 | int ret; |
| 255 | |
| 256 | ret = gnutls_x509_crt_get_extension_by_oid ((gnutls_x509_crt_t)cert, |
| 257 | CS oid, idx, CS cp1, &siz, &crit); |
| 258 | if (ret != GNUTLS_E_SHORT_MEMORY_BUFFER) |
| 259 | return g_err("ge0", __FUNCTION__, ret); |
| 260 | |
| 261 | cp1 = store_get(siz*4 + 1); |
| 262 | |
| 263 | ret = gnutls_x509_crt_get_extension_by_oid ((gnutls_x509_crt_t)cert, |
| 264 | CS oid, idx, CS cp1, &siz, &crit); |
| 265 | if (ret < 0) |
| 266 | return g_err("ge1", __FUNCTION__, ret); |
| 267 | |
| 268 | /* binary data, DER encoded */ |
| 269 | |
| 270 | /* just dump for now */ |
| 271 | for(cp3 = cp2 = cp1+siz; cp1 < cp2; cp1++) |
| 272 | cp3 += sprintf(CS cp3, "%.2x ", *cp1); |
| 273 | cp3[-1]= '\0'; |
| 274 | |
| 275 | return cp2; |
| 276 | } |
| 277 | |
| 278 | uschar * |
| 279 | tls_cert_subject_altname(void * cert, uschar * mod) |
| 280 | { |
| 281 | gstring * list = NULL; |
| 282 | size_t siz; |
| 283 | int ret; |
| 284 | uschar sep = '\n'; |
| 285 | uschar * tag = US""; |
| 286 | uschar * ele; |
| 287 | int match = -1; |
| 288 | |
| 289 | while (mod) |
| 290 | { |
| 291 | if (*mod == '>' && *++mod) sep = *mod++; |
| 292 | else if (Ustrcmp(mod, "dns")==0) { match = GNUTLS_SAN_DNSNAME; mod += 3; } |
| 293 | else if (Ustrcmp(mod, "uri")==0) { match = GNUTLS_SAN_URI; mod += 3; } |
| 294 | else if (Ustrcmp(mod, "mail")==0) { match = GNUTLS_SAN_RFC822NAME; mod += 4; } |
| 295 | else continue; |
| 296 | |
| 297 | if (*mod++ != ',') |
| 298 | break; |
| 299 | } |
| 300 | |
| 301 | for (int index = 0;; index++) |
| 302 | { |
| 303 | siz = 0; |
| 304 | switch(ret = gnutls_x509_crt_get_subject_alt_name( |
| 305 | (gnutls_x509_crt_t)cert, index, NULL, &siz, NULL)) |
| 306 | { |
| 307 | case GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE: |
| 308 | return string_from_gstring(list); /* no more elements; normal exit */ |
| 309 | |
| 310 | case GNUTLS_E_SHORT_MEMORY_BUFFER: |
| 311 | break; |
| 312 | |
| 313 | default: |
| 314 | return g_err("gs0", __FUNCTION__, ret); |
| 315 | } |
| 316 | |
| 317 | ele = store_get(siz+1); |
| 318 | if ((ret = gnutls_x509_crt_get_subject_alt_name( |
| 319 | (gnutls_x509_crt_t)cert, index, ele, &siz, NULL)) < 0) |
| 320 | return g_err("gs1", __FUNCTION__, ret); |
| 321 | ele[siz] = '\0'; |
| 322 | |
| 323 | if ( match != -1 && match != ret /* wrong type of SAN */ |
| 324 | || Ustrlen(ele) != siz) /* contains a NUL */ |
| 325 | continue; |
| 326 | switch (ret) |
| 327 | { |
| 328 | case GNUTLS_SAN_DNSNAME: tag = US"DNS"; break; |
| 329 | case GNUTLS_SAN_URI: tag = US"URI"; break; |
| 330 | case GNUTLS_SAN_RFC822NAME: tag = US"MAIL"; break; |
| 331 | default: continue; /* ignore unrecognised types */ |
| 332 | } |
| 333 | list = string_append_listele(list, sep, |
| 334 | match == -1 ? string_sprintf("%s=%s", tag, ele) : ele); |
| 335 | } |
| 336 | /*NOTREACHED*/ |
| 337 | } |
| 338 | |
| 339 | uschar * |
| 340 | tls_cert_ocsp_uri(void * cert, uschar * mod) |
| 341 | { |
| 342 | #if GNUTLS_VERSION_NUMBER >= 0x030000 |
| 343 | gnutls_datum_t uri; |
| 344 | int ret; |
| 345 | uschar sep = '\n'; |
| 346 | gstring * list = NULL; |
| 347 | |
| 348 | if (mod) |
| 349 | if (*mod == '>' && *++mod) sep = *mod++; |
| 350 | |
| 351 | for (int index = 0;; index++) |
| 352 | { |
| 353 | ret = gnutls_x509_crt_get_authority_info_access((gnutls_x509_crt_t)cert, |
| 354 | index, GNUTLS_IA_OCSP_URI, &uri, NULL); |
| 355 | |
| 356 | if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) |
| 357 | return string_from_gstring(list); |
| 358 | if (ret < 0) |
| 359 | return g_err("gai", __FUNCTION__, ret); |
| 360 | |
| 361 | list = string_append_listele_n(list, sep, uri.data, uri.size); |
| 362 | } |
| 363 | /*NOTREACHED*/ |
| 364 | |
| 365 | #else |
| 366 | |
| 367 | expand_string_message = |
| 368 | string_sprintf("%s: OCSP support with GnuTLS requires version 3.0.0\n", |
| 369 | __FUNCTION__); |
| 370 | return NULL; |
| 371 | |
| 372 | #endif |
| 373 | } |
| 374 | |
| 375 | uschar * |
| 376 | tls_cert_crl_uri(void * cert, uschar * mod) |
| 377 | { |
| 378 | int ret; |
| 379 | uschar sep = '\n'; |
| 380 | gstring * list = NULL; |
| 381 | uschar * ele; |
| 382 | |
| 383 | if (mod) |
| 384 | if (*mod == '>' && *++mod) sep = *mod++; |
| 385 | |
| 386 | for (int index = 0;; index++) |
| 387 | { |
| 388 | size_t siz = 0; |
| 389 | switch(ret = gnutls_x509_crt_get_crl_dist_points( |
| 390 | (gnutls_x509_crt_t)cert, index, NULL, &siz, NULL, NULL)) |
| 391 | { |
| 392 | case GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE: |
| 393 | return string_from_gstring(list); |
| 394 | case GNUTLS_E_SHORT_MEMORY_BUFFER: |
| 395 | break; |
| 396 | default: |
| 397 | return g_err("gc0", __FUNCTION__, ret); |
| 398 | } |
| 399 | |
| 400 | ele = store_get(siz); |
| 401 | if ((ret = gnutls_x509_crt_get_crl_dist_points( |
| 402 | (gnutls_x509_crt_t)cert, index, ele, &siz, NULL, NULL)) < 0) |
| 403 | return g_err("gc1", __FUNCTION__, ret); |
| 404 | |
| 405 | list = string_append_listele_n(list, sep, ele, siz); |
| 406 | } |
| 407 | /*NOTREACHED*/ |
| 408 | } |
| 409 | |
| 410 | |
| 411 | /***************************************************** |
| 412 | * Certificate operator routines |
| 413 | *****************************************************/ |
| 414 | uschar * |
| 415 | tls_cert_der_b64(void * cert) |
| 416 | { |
| 417 | size_t len = 0; |
| 418 | uschar * cp = NULL; |
| 419 | int fail; |
| 420 | |
| 421 | if ( (fail = gnutls_x509_crt_export((gnutls_x509_crt_t)cert, |
| 422 | GNUTLS_X509_FMT_DER, cp, &len)) != GNUTLS_E_SHORT_MEMORY_BUFFER |
| 423 | || !(cp = store_get((int)len)) |
| 424 | || (fail = gnutls_x509_crt_export((gnutls_x509_crt_t)cert, |
| 425 | GNUTLS_X509_FMT_DER, cp, &len)) |
| 426 | ) |
| 427 | { |
| 428 | log_write(0, LOG_MAIN, "TLS error in certificate export: %s", |
| 429 | gnutls_strerror(fail)); |
| 430 | return NULL; |
| 431 | } |
| 432 | return b64encode(CUS cp, (int)len); |
| 433 | } |
| 434 | |
| 435 | |
| 436 | static uschar * |
| 437 | fingerprint(gnutls_x509_crt_t cert, gnutls_digest_algorithm_t algo) |
| 438 | { |
| 439 | int ret; |
| 440 | size_t siz = 0; |
| 441 | uschar * cp; |
| 442 | uschar * cp2; |
| 443 | |
| 444 | if ((ret = gnutls_x509_crt_get_fingerprint(cert, algo, NULL, &siz)) |
| 445 | != GNUTLS_E_SHORT_MEMORY_BUFFER) |
| 446 | return g_err("gf0", __FUNCTION__, ret); |
| 447 | |
| 448 | cp = store_get(siz*3+1); |
| 449 | if ((ret = gnutls_x509_crt_get_fingerprint(cert, algo, cp, &siz)) < 0) |
| 450 | return g_err("gf1", __FUNCTION__, ret); |
| 451 | |
| 452 | for (uschar * cp3 = cp2 = cp+siz; cp < cp2; cp++) |
| 453 | cp3 += sprintf(CS cp3, "%02X", *cp); |
| 454 | return cp2; |
| 455 | } |
| 456 | |
| 457 | |
| 458 | uschar * |
| 459 | tls_cert_fprt_md5(void * cert) |
| 460 | { |
| 461 | return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_MD5); |
| 462 | } |
| 463 | |
| 464 | uschar * |
| 465 | tls_cert_fprt_sha1(void * cert) |
| 466 | { |
| 467 | return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_SHA1); |
| 468 | } |
| 469 | |
| 470 | uschar * |
| 471 | tls_cert_fprt_sha256(void * cert) |
| 472 | { |
| 473 | return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_SHA256); |
| 474 | } |
| 475 | |
| 476 | |
| 477 | /* vi: aw ai sw=2 |
| 478 | */ |
| 479 | /* End of tlscert-gnu.c */ |