src/tlscert-gnu.c

   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 size_t sz = sizeof(bin);
 177 uschar * sp;
 178 uschar * dp;
 179 int ret;
 180
 181 if ((ret = gnutls_x509_crt_get_serial((gnutls_x509_crt_t)cert,
 182     bin, &sz)))
 183   return g_err("gs0", __FUNCTION__, ret);
 184
 185 for(dp = txt, sp = bin; sz; sz--)
 186   dp += sprintf(CS dp, "%.2x", *sp++);
 187 for(sp = txt; sp[0]=='0' && sp[1]; ) sp++;      /* leading zeroes */
 188 return string_copy(sp);
 189 }
 190
 191 uschar *
 192 tls_cert_signature(void * cert, uschar * mod)
 193 {
 194 uschar * cp1 = NULL;
 195 uschar * cp2;
 196 uschar * cp3;
 197 size_t len = 0;
 198 int ret;
 199
 200 if ((ret = gnutls_x509_crt_get_signature((gnutls_x509_crt_t)cert, CS cp1, &len))
 201     != GNUTLS_E_SHORT_MEMORY_BUFFER)
 202   return g_err("gs0", __FUNCTION__, ret);
 203
 204 cp1 = store_get(len*4+1);
 205 if (gnutls_x509_crt_get_signature((gnutls_x509_crt_t)cert, CS cp1, &len) != 0)
 206   return g_err("gs1", __FUNCTION__, ret);
 207
 208 for(cp3 = cp2 = cp1+len; cp1 < cp2; cp1++)
 209   cp3 += sprintf(CS cp3, "%.2x ", *cp1);
 210 cp3[-1]= '\0';
 211
 212 return cp2;
 213 }
 214
 215 uschar *
 216 tls_cert_signature_algorithm(void * cert, uschar * mod)
 217 {
 218 gnutls_sign_algorithm_t algo =
 219   gnutls_x509_crt_get_signature_algorithm((gnutls_x509_crt_t)cert);
 220 return algo < 0 ? NULL : string_copy(US gnutls_sign_get_name(algo));
 221 }
 222
 223 uschar *
 224 tls_cert_subject(void * cert, uschar * mod)
 225 {
 226 uschar * cp = NULL;
 227 int ret;
 228 size_t siz = 0;
 229
 230 if ((ret = gnutls_x509_crt_get_dn(cert, CS cp, &siz))
 231     != GNUTLS_E_SHORT_MEMORY_BUFFER)
 232   return g_err("gs0", __FUNCTION__, ret);
 233
 234 cp = store_get(siz);
 235 if ((ret = gnutls_x509_crt_get_dn(cert, CS cp, &siz)) < 0)
 236   return g_err("gs1", __FUNCTION__, ret);
 237
 238 return mod ? tls_field_from_dn(cp, mod) : cp;
 239 }
 240
 241 uschar *
 242 tls_cert_version(void * cert, uschar * mod)
 243 {
 244 return string_sprintf("%d", gnutls_x509_crt_get_version(cert));
 245 }
 246
 247 uschar *
 248 tls_cert_ext_by_oid(void * cert, uschar * oid, int idx)
 249 {
 250 uschar * cp1 = NULL;
 251 uschar * cp2;
 252 uschar * cp3;
 253 size_t siz = 0;
 254 unsigned int crit;
 255 int ret;
 256
 257 ret = gnutls_x509_crt_get_extension_by_oid ((gnutls_x509_crt_t)cert,
 258   CS oid, idx, CS cp1, &siz, &crit);
 259 if (ret != GNUTLS_E_SHORT_MEMORY_BUFFER)
 260   return g_err("ge0", __FUNCTION__, ret);
 261
 262 cp1 = store_get(siz*4 + 1);
 263
 264 ret = gnutls_x509_crt_get_extension_by_oid ((gnutls_x509_crt_t)cert,
 265   CS oid, idx, CS cp1, &siz, &crit);
 266 if (ret < 0)
 267   return g_err("ge1", __FUNCTION__, ret);
 268
 269 /* binary data, DER encoded */
 270
 271 /* just dump for now */
 272 for(cp3 = cp2 = cp1+siz; cp1 < cp2; cp1++)
 273   cp3 += sprintf(CS cp3, "%.2x ", *cp1);
 274 cp3[-1]= '\0';
 275
 276 return cp2;
 277 }
 278
 279 uschar *
 280 tls_cert_subject_altname(void * cert, uschar * mod)
 281 {
 282 gstring * list = NULL;
 283 int index;
 284 size_t siz;
 285 int ret;
 286 uschar sep = '\n';
 287 uschar * tag = US"";
 288 uschar * ele;
 289 int match = -1;
 290
 291 while (mod)
 292   {
 293   if (*mod == '>' && *++mod) sep = *mod++;
 294   else if (Ustrcmp(mod, "dns")==0) { match = GNUTLS_SAN_DNSNAME; mod += 3; }
 295   else if (Ustrcmp(mod, "uri")==0) { match = GNUTLS_SAN_URI; mod += 3; }
 296   else if (Ustrcmp(mod, "mail")==0) { match = GNUTLS_SAN_RFC822NAME; mod += 4; }
 297   else continue;
 298
 299   if (*mod++ != ',')
 300     break;
 301   }
 302
 303 for(index = 0;; index++)
 304   {
 305   siz = 0;
 306   switch(ret = gnutls_x509_crt_get_subject_alt_name(
 307       (gnutls_x509_crt_t)cert, index, NULL, &siz, NULL))
 308     {
 309     case GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE:
 310       return string_from_gstring(list); /* no more elements; normal exit */
 311
 312     case GNUTLS_E_SHORT_MEMORY_BUFFER:
 313       break;
 314
 315     default:
 316       return g_err("gs0", __FUNCTION__, ret);
 317     }
 318
 319   ele = store_get(siz+1);
 320   if ((ret = gnutls_x509_crt_get_subject_alt_name(
 321     (gnutls_x509_crt_t)cert, index, ele, &siz, NULL)) < 0)
 322     return g_err("gs1", __FUNCTION__, ret);
 323   ele[siz] = '\0';
 324
 325   if (  match != -1 && match != ret     /* wrong type of SAN */
 326      || Ustrlen(ele) != siz)            /* contains a NUL */
 327     continue;
 328   switch (ret)
 329     {
 330     case GNUTLS_SAN_DNSNAME:    tag = US"DNS";  break;
 331     case GNUTLS_SAN_URI:        tag = US"URI";  break;
 332     case GNUTLS_SAN_RFC822NAME: tag = US"MAIL"; break;
 333     default: continue;        /* ignore unrecognised types */
 334     }
 335   list = string_append_listele(list, sep,
 336           match == -1 ? string_sprintf("%s=%s", tag, ele) : ele);
 337   }
 338 /*NOTREACHED*/
 339 }
 340
 341 uschar *
 342 tls_cert_ocsp_uri(void * cert, uschar * mod)
 343 {
 344 #if GNUTLS_VERSION_NUMBER >= 0x030000
 345 gnutls_datum_t uri;
 346 int ret;
 347 uschar sep = '\n';
 348 int index;
 349 gstring * list = NULL;
 350
 351 if (mod)
 352   if (*mod == '>' && *++mod) sep = *mod++;
 353
 354 for(index = 0;; index++)
 355   {
 356   ret = gnutls_x509_crt_get_authority_info_access((gnutls_x509_crt_t)cert,
 357           index, GNUTLS_IA_OCSP_URI, &uri, NULL);
 358
 359   if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
 360     return string_from_gstring(list);
 361   if (ret < 0)
 362     return g_err("gai", __FUNCTION__, ret);
 363
 364   list = string_append_listele_n(list, sep, uri.data, uri.size);
 365   }
 366 /*NOTREACHED*/
 367
 368 #else
 369
 370 expand_string_message =
 371   string_sprintf("%s: OCSP support with GnuTLS requires version 3.0.0\n",
 372     __FUNCTION__);
 373 return NULL;
 374
 375 #endif
 376 }
 377
 378 uschar *
 379 tls_cert_crl_uri(void * cert, uschar * mod)
 380 {
 381 int ret;
 382 size_t siz;
 383 uschar sep = '\n';
 384 int index;
 385 gstring * list = NULL;
 386 uschar * ele;
 387
 388 if (mod)
 389   if (*mod == '>' && *++mod) sep = *mod++;
 390
 391 for(index = 0;; index++)
 392   {
 393   siz = 0;
 394   switch(ret = gnutls_x509_crt_get_crl_dist_points(
 395     (gnutls_x509_crt_t)cert, index, NULL, &siz, NULL, NULL))
 396     {
 397     case GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE:
 398       return string_from_gstring(list);
 399     case GNUTLS_E_SHORT_MEMORY_BUFFER:
 400       break;
 401     default:
 402       return g_err("gc0", __FUNCTION__, ret);
 403     }
 404
 405   ele = store_get(siz);
 406   if ((ret = gnutls_x509_crt_get_crl_dist_points(
 407       (gnutls_x509_crt_t)cert, index, ele, &siz, NULL, NULL)) < 0)
 408     return g_err("gc1", __FUNCTION__, ret);
 409
 410   list = string_append_listele_n(list, sep, ele, siz);
 411   }
 412 /*NOTREACHED*/
 413 }
 414
 415
 416 /*****************************************************
 417 *  Certificate operator routines
 418 *****************************************************/
 419 uschar *
 420 tls_cert_der_b64(void * cert)
 421 {
 422 size_t len = 0;
 423 uschar * cp = NULL;
 424 int fail;
 425
 426 if (  (fail = gnutls_x509_crt_export((gnutls_x509_crt_t)cert,
 427         GNUTLS_X509_FMT_DER, cp, &len)) != GNUTLS_E_SHORT_MEMORY_BUFFER
 428    || !(cp = store_get((int)len))
 429    || (fail = gnutls_x509_crt_export((gnutls_x509_crt_t)cert,
 430         GNUTLS_X509_FMT_DER, cp, &len))
 431    )
 432   {
 433   log_write(0, LOG_MAIN, "TLS error in certificate export: %s",
 434     gnutls_strerror(fail));
 435   return NULL;
 436   }
 437 return b64encode(cp, (int)len);
 438 }
 439
 440
 441 static uschar *
 442 fingerprint(gnutls_x509_crt_t cert, gnutls_digest_algorithm_t algo)
 443 {
 444 int ret;
 445 size_t siz = 0;
 446 uschar * cp;
 447 uschar * cp2;
 448 uschar * cp3;
 449
 450 if ((ret = gnutls_x509_crt_get_fingerprint(cert, algo, NULL, &siz))
 451     != GNUTLS_E_SHORT_MEMORY_BUFFER)
 452   return g_err("gf0", __FUNCTION__, ret);
 453
 454 cp = store_get(siz*3+1);
 455 if ((ret = gnutls_x509_crt_get_fingerprint(cert, algo, cp, &siz)) < 0)
 456   return g_err("gf1", __FUNCTION__, ret);
 457
 458 for (cp3 = cp2 = cp+siz; cp < cp2; cp++)
 459   cp3 += sprintf(CS cp3, "%02X", *cp);
 460 return cp2;
 461 }
 462
 463
 464 uschar *
 465 tls_cert_fprt_md5(void * cert)
 466 {
 467 return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_MD5);
 468 }
 469
 470 uschar *
 471 tls_cert_fprt_sha1(void * cert)
 472 {
 473 return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_SHA1);
 474 }
 475
 476 uschar *
 477 tls_cert_fprt_sha256(void * cert)
 478 {
 479 return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_SHA256);
 480 }
 481
 482
 483 /* vi: aw ai sw=2
 484 */
 485 /* End of tlscert-gnu.c */