src/tlscert-gnu.c

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