src/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 = 0;
  30 uschar * cp;
  31
  32 if (gnutls_x509_crt_export((gnutls_x509_crt_t)cert,
  33     GNUTLS_X509_FMT_PEM, buf, &sz))
  34   return 1;
  35 if ((cp = string_printing(buf)) != buf)
  36   {
  37   Ustrncpy(buf, cp, buflen);
  38   if (buf[buflen-1])
  39     fail = 1;
  40   }
  41 store_reset(reset_point);
  42 return fail;
  43 }
  44
  45 int
  46 tls_import_cert(const uschar * buf, void ** cert)
  47 {
  48 void * reset_point = store_get(0);
  49 gnutls_datum_t datum;
  50 gnutls_x509_crt_t crt;
  51 int fail = 0;
  52
  53 gnutls_global_init();
  54 gnutls_x509_crt_init(&crt);
  55
  56 datum.data = string_unprinting(US buf);
  57 datum.size = Ustrlen(datum.data);
  58 if (gnutls_x509_crt_import(crt, &datum, GNUTLS_X509_FMT_PEM))
  59   fail = 1;
  60 else
  61   *cert = (void *)crt;
  62
  63 store_reset(reset_point);
  64 return fail;
  65 }
  66
  67 void
  68 tls_free_cert(void * cert)
  69 {
  70 gnutls_x509_crt_deinit((gnutls_x509_crt_t) cert);
  71 gnutls_global_deinit();
  72 }
  73
  74 /*****************************************************
  75 *  Certificate field extraction routines
  76 *****************************************************/
  77 static uschar *
  78 g_err(const char * tag, const char * from, int gnutls_err)
  79 {
  80 expand_string_message = string_sprintf(stderr,
  81   "%s: %s fail: %s\n", from, tag, gnutls_strerror(gnutls_err));
  82 return NULL;
  83 }
  84
  85
  86 static uschar *
  87 time_copy(time_t t)
  88 {
  89 uschar * cp = store_get(32);
  90 struct tm * tp = gmtime(&t);
  91 size_t len = strftime(CS cp, 32, "%b %e %T %Y %Z", tp);
  92 return len > 0 ? cp : NULL;
  93 }
  94
  95 /**/
  96
  97 uschar *
  98 tls_cert_issuer(void * cert, uschar * mod)
  99 {
 100 uschar txt[256];
 101 size_t sz = sizeof(txt);
 102 return ( gnutls_x509_crt_get_issuer_dn(cert, CS txt, &sz) == 0 )
 103   ? string_copy(txt) : NULL;
 104 }
 105
 106 uschar *
 107 tls_cert_not_after(void * cert, uschar * mod)
 108 {
 109 return time_copy(
 110   gnutls_x509_crt_get_expiration_time((gnutls_x509_crt_t)cert));
 111 }
 112
 113 uschar *
 114 tls_cert_not_before(void * cert, uschar * mod)
 115 {
 116 return time_copy(
 117   gnutls_x509_crt_get_activation_time((gnutls_x509_crt_t)cert));
 118 }
 119
 120 uschar *
 121 tls_cert_serial_number(void * cert, uschar * mod)
 122 {
 123 uschar bin[50], txt[150];
 124 size_t sz = sizeof(bin);
 125 uschar * sp;
 126 uschar * dp;
 127
 128 if (gnutls_x509_crt_get_serial((gnutls_x509_crt_t)cert,
 129     bin, &sz) || sz > sizeof(bin))
 130   return NULL;
 131 for(dp = txt, sp = bin; sz; dp += 2, sp++, sz--)
 132   sprintf(dp, "%.2x", *sp);
 133 for(sp = txt; sp[0]=='0' && sp[1]; ) sp++;      /* leading zeroes */
 134 return string_copy(sp);
 135 }
 136
 137 uschar *
 138 tls_cert_signature(void * cert, uschar * mod)
 139 {
 140 uschar * cp1;
 141 uschar * cp2;
 142 uschar * cp3;
 143 size_t len = 0;
 144 int ret;
 145
 146 if ((ret = gnutls_x509_crt_get_signature((gnutls_x509_crt_t)cert, cp1, &len)) !=
 147         GNUTLS_E_SHORT_MEMORY_BUFFER)
 148   {
 149   fprintf(stderr, "%s: gs0 fail: %s\n", __FUNCTION__, gnutls_strerror(ret));
 150   return NULL;
 151   }
 152
 153 cp1 = store_get(len*4+1);
 154
 155 if (gnutls_x509_crt_get_signature((gnutls_x509_crt_t)cert, cp1, &len) != 0)
 156   {
 157   fprintf(stderr, "%s: gs1 fail\n", __FUNCTION__);
 158   return NULL;
 159   }
 160
 161 for(cp3 = cp2 = cp1+len; cp1 < cp2; cp3 += 3, cp1++)
 162   sprintf(cp3, "%.2x ", *cp1);
 163 cp3[-1]= '\0';
 164
 165 return cp2;
 166 }
 167
 168 uschar *
 169 tls_cert_signature_algorithm(void * cert, uschar * mod)
 170 {
 171 gnutls_sign_algorithm_t algo =
 172   gnutls_x509_crt_get_signature_algorithm((gnutls_x509_crt_t)cert);
 173 return algo < 0 ? NULL : string_copy(gnutls_sign_get_name(algo));
 174 }
 175
 176 uschar *
 177 tls_cert_subject(void * cert, uschar * mod)
 178 {
 179 uschar * cp = NULL;
 180 int ret;
 181 size_t siz = 0;
 182
 183 ret = gnutls_x509_crt_get_dn(cert, cp, &siz);
 184 if (ret != GNUTLS_E_SHORT_MEMORY_BUFFER)
 185   {
 186   fprintf(stderr, "%s: gs0 fail: %s\n", __FUNCTION__, gnutls_strerror(ret));
 187   return NULL;
 188   }
 189
 190 cp = store_get(siz);
 191
 192 ret = gnutls_x509_crt_get_dn(cert, cp, &siz);
 193 if (ret < 0)
 194   {
 195   fprintf(stderr, "%s: gs1 fail: %s\n", __FUNCTION__, gnutls_strerror(ret));
 196   return NULL;
 197   }
 198
 199 return cp;
 200 }
 201
 202 uschar *
 203 tls_cert_version(void * cert, uschar * mod)
 204 {
 205 return string_sprintf("%d", gnutls_x509_crt_get_version(cert));
 206 }
 207
 208 uschar *
 209 tls_cert_ext_by_oid(void * cert, uschar * oid, int idx)
 210 {
 211 uschar * cp1 = NULL;
 212 uschar * cp2;
 213 uschar * cp3;
 214 size_t siz = 0;
 215 unsigned int crit;
 216 int ret;
 217
 218 ret = gnutls_x509_crt_get_extension_by_oid ((gnutls_x509_crt_t)cert,
 219   oid, idx, cp1, &siz, &crit);
 220 if (ret != GNUTLS_E_SHORT_MEMORY_BUFFER)
 221   return g_err("ge0", __FUNCTION__, ret);
 222
 223 cp1 = store_get(siz*4 + 1);
 224
 225 ret = gnutls_x509_crt_get_extension_by_oid ((gnutls_x509_crt_t)cert,
 226   oid, idx, cp1, &siz, &crit);
 227 if (ret < 0)
 228   return g_err("ge1", __FUNCTION__, ret);
 229
 230 /* binary data, DER encoded */
 231
 232 /* just dump for now */
 233 for(cp3 = cp2 = cp1+siz; cp1 < cp2; cp3 += 3, cp1++)
 234   sprintf(cp3, "%.2x ", *cp1);
 235 cp3[-1]= '\0';
 236
 237 return cp2;
 238 }
 239
 240 uschar *
 241 tls_cert_subject_altname(void * cert, uschar * mod)
 242 {
 243 uschar * list = NULL;
 244 int index;
 245 size_t siz;
 246 int ret;
 247 uschar sep = '\n';
 248 uschar * tag = US"";
 249 uschar * ele;
 250 int match = -1;
 251
 252 while (mod)
 253   {
 254   if (*mod == '>' && *++mod) sep = *mod++;
 255   else if (Ustrcmp(mod, "dns")==0) { match = GNUTLS_SAN_DNSNAME; mod += 3; }
 256   else if (Ustrcmp(mod, "uri")==0) { match = GNUTLS_SAN_URI; mod += 3; }
 257   else if (Ustrcmp(mod, "mail")==0) { match = GNUTLS_SAN_RFC822NAME; mod += 4; }
 258   else continue;
 259
 260   if (*mod++ != ',')
 261     break;
 262   }
 263
 264 for(index = 0;; index++)
 265   {
 266   siz = 0;
 267   switch(ret = gnutls_x509_crt_get_subject_alt_name(
 268     (gnutls_x509_crt_t)cert, index, NULL, &siz, NULL))
 269     {
 270     case GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE:
 271       return list;      /* no more elements; normal exit */
 272
 273     case GNUTLS_E_SHORT_MEMORY_BUFFER:
 274       break;
 275
 276     default:
 277       return g_err("gs0", __FUNCTION__, ret);
 278     }
 279
 280   ele = store_get(siz+1);
 281   if ((ret = gnutls_x509_crt_get_subject_alt_name(
 282     (gnutls_x509_crt_t)cert, index, ele, &siz, NULL)) < 0)
 283     return g_err("gs1", __FUNCTION__, ret);
 284   ele[siz] = '\0';
 285
 286   if (match != -1 && match != ret)
 287     continue;
 288   switch (ret)
 289     {
 290     case GNUTLS_SAN_DNSNAME:    tag = US"DNS";  break;
 291     case GNUTLS_SAN_URI:        tag = US"URI";  break;
 292     case GNUTLS_SAN_RFC822NAME: tag = US"MAIL"; break;
 293     default: continue;        /* ignore unrecognised types */
 294     }
 295   list = string_append_listele(list, sep,
 296           match == -1 ? string_sprintf("%s=%s", tag, ele) : ele);
 297   }
 298 /*NOTREACHED*/
 299 }
 300
 301 uschar *
 302 tls_cert_ocsp_uri(void * cert, uschar * mod)
 303 {
 304 #if GNUTLS_VERSION_NUMBER >= 0x030000
 305 gnutls_datum_t uri;
 306 int ret;
 307 uschar sep = '\n';
 308 int index;
 309 uschar * list = NULL;
 310
 311 if (mod)
 312   if (*mod == '>' && *++mod) sep = *mod++;
 313
 314 for(index = 0;; index++)
 315   {
 316   ret = gnutls_x509_crt_get_authority_info_access((gnutls_x509_crt_t)cert,
 317           index, GNUTLS_IA_OCSP_URI, &uri, NULL);
 318
 319   if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE)
 320     return list;
 321   if (ret < 0)
 322     return g_err("gai", __FUNCTION__, ret);
 323
 324   list = string_append_listele(list, sep,
 325             string_copyn(uri.data, uri.size));
 326   }
 327 /*NOTREACHED*/
 328
 329 #else
 330
 331 expand_string_message =
 332   string_sprintf("%s: OCSP support with GnuTLS requires version 3.0.0\n",
 333     __FUNCTION__);
 334 return NULL;
 335
 336 #endif
 337 }
 338
 339 uschar *
 340 tls_cert_crl_uri(void * cert, uschar * mod)
 341 {
 342 int ret;
 343 size_t siz;
 344 uschar sep = '\n';
 345 int index;
 346 uschar * list = NULL;
 347 uschar * ele;
 348
 349 if (mod)
 350   if (*mod == '>' && *++mod) sep = *mod++;
 351
 352 for(index = 0;; index++)
 353   {
 354   siz = 0;
 355   switch(ret = gnutls_x509_crt_get_crl_dist_points(
 356     (gnutls_x509_crt_t)cert, index, NULL, &siz, NULL, NULL))
 357     {
 358     case GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE:
 359       return list;
 360     case GNUTLS_E_SHORT_MEMORY_BUFFER:
 361       break;
 362     default:
 363       return g_err("gc0", __FUNCTION__, ret);
 364     }
 365
 366   ele = store_get(siz+1);
 367   if ((ret = gnutls_x509_crt_get_crl_dist_points(
 368       (gnutls_x509_crt_t)cert, index, ele, &siz, NULL, NULL)) < 0)
 369     return g_err("gc1", __FUNCTION__, ret);
 370
 371   ele[siz] = '\0';
 372   list = string_append_listele(list, sep, ele);
 373   }
 374 /*NOTREACHED*/
 375 }
 376
 377
 378 /*****************************************************
 379 *  Certificate operator routines
 380 *****************************************************/
 381 static uschar *
 382 fingerprint(gnutls_x509_crt_t cert, gnutls_digest_algorithm_t algo)
 383 {
 384 int ret;
 385 size_t siz = 0;
 386 uschar * cp;
 387 uschar * cp2;
 388 uschar * cp3;
 389
 390 if ((ret = gnutls_x509_crt_get_fingerprint(cert, algo, NULL, &siz))
 391     != GNUTLS_E_SHORT_MEMORY_BUFFER)
 392   return g_err("gf0", __FUNCTION__, ret);
 393
 394 cp = store_get(siz*3+1);
 395 if ((ret = gnutls_x509_crt_get_fingerprint(cert, algo, cp, &siz)) < 0)
 396   return g_err("gf1", __FUNCTION__, ret);
 397
 398 for (cp3 = cp2 = cp+siz; cp < cp2; cp++, cp3+=2)
 399   sprintf(cp3, "%02X",*cp);
 400 return cp2;
 401 }
 402
 403
 404 uschar *
 405 tls_cert_fprt_md5(void * cert)
 406 {
 407 return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_MD5);
 408 }
 409
 410 uschar *
 411 tls_cert_fprt_sha1(void * cert)
 412 {
 413 return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_SHA1);
 414 }
 415
 416 uschar *
 417 tls_cert_fprt_sha256(void * cert)
 418 {
 419 return fingerprint((gnutls_x509_crt_t)cert, GNUTLS_DIG_SHA256);
 420 }
 421
 422
 423 /* vi: aw ai sw=2
 424 */
 425 /* End of tlscert-gnu.c */