src/src/tlscert-openssl.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Jeremy Harris 2014 - 2016 */
   6
   7 /* This module provides TLS (aka SSL) support for Exim using the OpenSSL
   8 library. It is #included into the tls.c file when that library is used.
   9 */
  10
  11
  12 /* Heading stuff */
  13
  14 #include <openssl/lhash.h>
  15 #include <openssl/ssl.h>
  16 #include <openssl/err.h>
  17 #include <openssl/rand.h>
  18 #include <openssl/x509v3.h>
  19
  20 #if OPENSSL_VERSION_NUMBER >= 0x10100000L
  21 # define EXIM_HAVE_ASN1_MACROS
  22 #endif
  23
  24
  25 /*****************************************************
  26 *  Export/import a certificate, binary/printable
  27 *****************************************************/
  28 int
  29 tls_export_cert(uschar * buf, size_t buflen, void * cert)
  30 {
  31 BIO * bp = BIO_new(BIO_s_mem());
  32 int fail;
  33
  34 if ((fail = PEM_write_bio_X509(bp, (X509 *)cert) ? 0 : 1))
  35   log_write(0, LOG_MAIN, "TLS error in certificate export: %s",
  36     ERR_error_string(ERR_get_error(), NULL));
  37 else
  38   {
  39   char * cp = CS buf;
  40   int n;
  41   buflen -= 2;
  42   for(;;)
  43     {
  44     if ((n = BIO_gets(bp, cp, (int)buflen)) <= 0) break;
  45     cp += n+1;
  46     buflen -= n+1;
  47     cp[-2] = '\\'; cp[-1] = 'n'; /* newline->"\n" */
  48     }                            /* compat with string_printing() */
  49   *cp = '\0';
  50   }
  51
  52 BIO_free(bp);
  53 return fail;
  54 }
  55
  56 int
  57 tls_import_cert(const uschar * buf, void ** cert)
  58 {
  59 void * reset_point = store_get(0);
  60 const uschar * cp = string_unprinting(US buf);
  61 BIO * bp;
  62 X509 * x = *(X509 **)cert;
  63 int fail = 0;
  64
  65 if (x) X509_free(x);
  66
  67 bp = BIO_new_mem_buf(US cp, -1);
  68 if (!(x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
  69   {
  70   log_write(0, LOG_MAIN, "TLS error in certificate import: %s",
  71     ERR_error_string(ERR_get_error(), NULL));
  72   fail = 1;
  73   }
  74 else
  75   *cert = (void *)x;
  76 BIO_free(bp);
  77 store_reset(reset_point);
  78 return fail;
  79 }
  80
  81 void
  82 tls_free_cert(void ** cert)
  83 {
  84 X509 * x = *(X509 **)cert;
  85 if (x)
  86   {
  87   X509_free(x);
  88   *cert = NULL;
  89   }
  90 }
  91
  92
  93 /*****************************************************
  94 *  Certificate field extraction routines
  95 *****************************************************/
  96
  97 /* First, some internal service functions */
  98
  99 static uschar *
 100 badalloc(void)
 101 {
 102 expand_string_message = US"allocation failure";
 103 return NULL;
 104 }
 105
 106 static uschar *
 107 bio_string_copy(BIO * bp, int len)
 108 {
 109 uschar * cp = US"";
 110 len = len > 0 ? (int) BIO_get_mem_data(bp, &cp) : 0;
 111 cp = string_copyn(cp, len);
 112 BIO_free(bp);
 113 return cp;
 114 }
 115
 116 static uschar *
 117 asn1_time_copy(const ASN1_TIME * asntime, uschar * mod)
 118 {
 119 uschar * s = NULL;
 120 BIO * bp = BIO_new(BIO_s_mem());
 121 int len;
 122
 123 if (!bp)
 124   return badalloc();
 125 len = ASN1_TIME_print(bp, asntime);
 126 len = len > 0 ? (int) BIO_get_mem_data(bp, CSS &s) : 0;
 127
 128 if (mod && Ustrcmp(mod, "raw") == 0)            /* native ASN */
 129   s = string_copyn(s, len);
 130 else
 131   {
 132   struct tm tm;
 133   struct tm * tm_p = &tm;
 134   BOOL mod_tz = TRUE;
 135   uschar * tz = to_tz(US"GMT0");    /* need to call strptime with baseline TZ */
 136
 137   /* Parse OpenSSL ASN1_TIME_print output.  A shame there seems to
 138   be no other interface for the times.
 139   */
 140
 141   /*XXX %Z might be glibc-specific?  Solaris has it, at least*/
 142   /*XXX should we switch to POSIX locale for this? */
 143   tm.tm_isdst = 0;
 144   if (!len || !strptime(CCS s, "%b %e %T %Y %Z", &tm))
 145     expand_string_message = US"failed time conversion";
 146
 147   else
 148     {
 149     time_t t = mktime(&tm);     /* make the tm self-consistent */
 150
 151     if (mod && Ustrcmp(mod, "int") == 0)        /* seconds since epoch */
 152       s = string_sprintf(TIME_T_FMT, t);
 153
 154     else
 155       {
 156       if (!timestamps_utc)      /* decoded string in local TZ */
 157         {                               /* shift to local TZ */
 158         restore_tz(tz);
 159         mod_tz = FALSE;
 160         tm_p = localtime(&t);
 161         }
 162       /* "utc" is default, and rfc5280 says cert times should be Zulu */
 163
 164       /* convert to string in our format */
 165       len = 32;
 166       s = store_get(len);
 167       strftime(CS s, (size_t)len, "%b %e %T %Y %z", tm_p);
 168       }
 169     }
 170
 171   if (mod_tz)
 172     restore_tz(tz);
 173   }
 174 BIO_free(bp);
 175 return s;
 176 }
 177
 178 static uschar *
 179 x509_name_copy(X509_NAME * name)
 180 {
 181 BIO * bp = BIO_new(BIO_s_mem());
 182 int len_good;
 183
 184 if (!bp) return badalloc();
 185
 186 len_good =
 187   X509_NAME_print_ex(bp, name, 0, XN_FLAG_RFC2253) >= 0
 188   ? 1 : 0;
 189 return bio_string_copy(bp, len_good);
 190 }
 191
 192 /**/
 193 /* Now the extractors, called from expand.c
 194 Arguments:
 195   cert          The certificate
 196   mod           Optional modifiers for the operator
 197
 198 Return:
 199   Allocated string with extracted value
 200 */
 201
 202 uschar *
 203 tls_cert_issuer(void * cert, uschar * mod)
 204 {
 205 uschar * cp = x509_name_copy(X509_get_issuer_name((X509 *)cert));
 206 return mod ? tls_field_from_dn(cp, mod) : cp;
 207 }
 208
 209 uschar *
 210 tls_cert_not_before(void * cert, uschar * mod)
 211 {
 212 return asn1_time_copy(X509_get_notBefore((X509 *)cert), mod);
 213 }
 214
 215 uschar *
 216 tls_cert_not_after(void * cert, uschar * mod)
 217 {
 218 return asn1_time_copy(X509_get_notAfter((X509 *)cert), mod);
 219 }
 220
 221 uschar *
 222 tls_cert_serial_number(void * cert, uschar * mod)
 223 {
 224 uschar txt[256];
 225 BIO * bp = BIO_new(BIO_s_mem());
 226 int len;
 227
 228 if (!bp) return badalloc();
 229
 230 len = i2a_ASN1_INTEGER(bp, X509_get_serialNumber((X509 *)cert));
 231 if (len < sizeof(txt))
 232   BIO_read(bp, txt, len);
 233 else
 234   len = 0;
 235 BIO_free(bp);
 236 return string_copynlc(txt, len);        /* lowercase */
 237 }
 238
 239 uschar *
 240 tls_cert_signature(void * cert, uschar * mod)
 241 {
 242 uschar * cp = NULL;
 243 BIO * bp = BIO_new(BIO_s_mem());
 244
 245 if (!bp) return badalloc();
 246
 247 if (X509_print_ex(bp, (X509 *)cert, 0,
 248   X509_FLAG_NO_HEADER | X509_FLAG_NO_VERSION | X509_FLAG_NO_SERIAL |
 249   X509_FLAG_NO_SIGNAME | X509_FLAG_NO_ISSUER | X509_FLAG_NO_VALIDITY |
 250   X509_FLAG_NO_SUBJECT | X509_FLAG_NO_PUBKEY | X509_FLAG_NO_EXTENSIONS |
 251   /* X509_FLAG_NO_SIGDUMP is the missing one */
 252   X509_FLAG_NO_AUX) == 1)
 253   {
 254   long len = BIO_get_mem_data(bp, &cp);
 255
 256   /* Strip leading "Signature Algorithm" line */
 257   while (*cp && *cp != '\n') { cp++; len--; }
 258
 259   cp = string_copyn(cp+1, len-1);
 260   }
 261 BIO_free(bp);
 262 return cp;
 263 }
 264
 265 uschar *
 266 tls_cert_signature_algorithm(void * cert, uschar * mod)
 267 {
 268 uschar * cp = NULL;
 269 BIO * bp = BIO_new(BIO_s_mem());
 270
 271 if (!bp) return badalloc();
 272
 273 if (X509_print_ex(bp, (X509 *)cert, 0,
 274   X509_FLAG_NO_HEADER | X509_FLAG_NO_VERSION | X509_FLAG_NO_SERIAL |
 275   /* X509_FLAG_NO_SIGNAME is the missing one */
 276   X509_FLAG_NO_ISSUER | X509_FLAG_NO_VALIDITY |
 277   X509_FLAG_NO_SUBJECT | X509_FLAG_NO_PUBKEY | X509_FLAG_NO_EXTENSIONS |
 278   X509_FLAG_NO_SIGDUMP | X509_FLAG_NO_AUX) == 1)
 279   {
 280   long len = BIO_get_mem_data(bp, &cp);
 281
 282   /* Strip leading "    Signature Algorithm: " and trailing newline */
 283   while (*cp && *cp != ':') { cp++; len--; }
 284   do { cp++; len--; } while (*cp && *cp == ' ');
 285   if (cp[len-1] == '\n') len--;
 286
 287   cp = string_copyn(cp, len);
 288   }
 289 BIO_free(bp);
 290 return cp;
 291 }
 292
 293 uschar *
 294 tls_cert_subject(void * cert, uschar * mod)
 295 {
 296 uschar * cp = x509_name_copy(X509_get_subject_name((X509 *)cert));
 297 return mod ? tls_field_from_dn(cp, mod) : cp;
 298 }
 299
 300 uschar *
 301 tls_cert_version(void * cert, uschar * mod)
 302 {
 303 return string_sprintf("%ld", X509_get_version((X509 *)cert));
 304 }
 305
 306 uschar *
 307 tls_cert_ext_by_oid(void * cert, uschar * oid, int idx)
 308 {
 309 int nid = OBJ_create(CS oid, "", "");
 310 int nidx = X509_get_ext_by_NID((X509 *)cert, nid, idx);
 311 X509_EXTENSION * ex = X509_get_ext((X509 *)cert, nidx);
 312 ASN1_OCTET_STRING * adata = X509_EXTENSION_get_data(ex);
 313 BIO * bp = BIO_new(BIO_s_mem());
 314 long len;
 315 uschar * cp1;
 316 uschar * cp2;
 317 uschar * cp3;
 318
 319 if (!bp) return badalloc();
 320
 321 #ifdef EXIM_HAVE_ASN1_MACROS
 322 ASN1_STRING_print(bp, adata);
 323 #else
 324 M_ASN1_OCTET_STRING_print(bp, adata);
 325 #endif
 326
 327 /* binary data, DER encoded */
 328 /* just dump for now */
 329 len = BIO_get_mem_data(bp, &cp1);
 330 cp3 = cp2 = store_get(len*3+1);
 331
 332 while(len)
 333   {
 334   cp2 += sprintf(CS cp2, "%.2x ", *cp1++);
 335   len--;
 336   }
 337 cp2[-1] = '\0';
 338
 339 return cp3;
 340 }
 341
 342 uschar *
 343 tls_cert_subject_altname(void * cert, uschar * mod)
 344 {
 345 gstring * list = NULL;
 346 STACK_OF(GENERAL_NAME) * san = (STACK_OF(GENERAL_NAME) *)
 347   X509_get_ext_d2i((X509 *)cert, NID_subject_alt_name, NULL, NULL);
 348 uschar osep = '\n';
 349 uschar * tag = US"";
 350 uschar * ele;
 351 int match = -1;
 352 int len;
 353
 354 if (!san) return NULL;
 355
 356 while (mod && *mod)
 357   {
 358   if (*mod == '>' && *++mod) osep = *mod++;
 359   else if (Ustrncmp(mod,"dns",3)==0) { match = GEN_DNS; mod += 3; }
 360   else if (Ustrncmp(mod,"uri",3)==0) { match = GEN_URI; mod += 3; }
 361   else if (Ustrncmp(mod,"mail",4)==0) { match = GEN_EMAIL; mod += 4; }
 362   else mod++;
 363
 364   if (*mod == ',') mod++;
 365   }
 366
 367 while (sk_GENERAL_NAME_num(san) > 0)
 368   {
 369   GENERAL_NAME * namePart = sk_GENERAL_NAME_pop(san);
 370   if (match != -1 && match != namePart->type)
 371     continue;
 372   switch (namePart->type)
 373     {
 374     case GEN_DNS:
 375       tag = US"DNS";
 376       ele = ASN1_STRING_data(namePart->d.dNSName);
 377       len = ASN1_STRING_length(namePart->d.dNSName);
 378       break;
 379     case GEN_URI:
 380       tag = US"URI";
 381       ele = ASN1_STRING_data(namePart->d.uniformResourceIdentifier);
 382       len = ASN1_STRING_length(namePart->d.uniformResourceIdentifier);
 383       break;
 384     case GEN_EMAIL:
 385       tag = US"MAIL";
 386       ele = ASN1_STRING_data(namePart->d.rfc822Name);
 387       len = ASN1_STRING_length(namePart->d.rfc822Name);
 388       break;
 389     default:
 390       continue; /* ignore unrecognised types */
 391     }
 392   if (ele[len]) /* not nul-terminated */
 393     ele = string_copyn(ele, len);
 394
 395   if (Ustrlen(ele) == len)      /* ignore any with embedded nul */
 396     list = string_append_listele(list, osep,
 397           match == -1 ? string_sprintf("%s=%s", tag, ele) : ele);
 398   }
 399
 400 sk_GENERAL_NAME_free(san);
 401 return string_from_gstring(list);
 402 }
 403
 404 uschar *
 405 tls_cert_ocsp_uri(void * cert, uschar * mod)
 406 {
 407 STACK_OF(ACCESS_DESCRIPTION) * ads = (STACK_OF(ACCESS_DESCRIPTION) *)
 408   X509_get_ext_d2i((X509 *)cert, NID_info_access, NULL, NULL);
 409 int adsnum = sk_ACCESS_DESCRIPTION_num(ads);
 410 int i;
 411 uschar sep = '\n';
 412 gstring * list = NULL;
 413
 414 if (mod)
 415   if (*mod == '>' && *++mod) sep = *mod++;
 416
 417 for (i = 0; i < adsnum; i++)
 418   {
 419   ACCESS_DESCRIPTION * ad = sk_ACCESS_DESCRIPTION_value(ads, i);
 420
 421   if (ad && OBJ_obj2nid(ad->method) == NID_ad_OCSP)
 422     list = string_append_listele_n(list, sep,
 423       ASN1_STRING_data(ad->location->d.ia5),
 424       ASN1_STRING_length(ad->location->d.ia5));
 425   }
 426 sk_ACCESS_DESCRIPTION_free(ads);
 427 return string_from_gstring(list);
 428 }
 429
 430 uschar *
 431 tls_cert_crl_uri(void * cert, uschar * mod)
 432 {
 433 STACK_OF(DIST_POINT) * dps = (STACK_OF(DIST_POINT) *)
 434   X509_get_ext_d2i((X509 *)cert,  NID_crl_distribution_points,
 435     NULL, NULL);
 436 DIST_POINT * dp;
 437 int dpsnum = sk_DIST_POINT_num(dps);
 438 int i;
 439 uschar sep = '\n';
 440 gstring * list = NULL;
 441
 442 if (mod)
 443   if (*mod == '>' && *++mod) sep = *mod++;
 444
 445 if (dps) for (i = 0; i < dpsnum; i++)
 446   if ((dp = sk_DIST_POINT_value(dps, i)))
 447     {
 448     STACK_OF(GENERAL_NAME) * names = dp->distpoint->name.fullname;
 449     GENERAL_NAME * np;
 450     int nnum = sk_GENERAL_NAME_num(names);
 451     int j;
 452
 453     for (j = 0; j < nnum; j++)
 454       if (  (np = sk_GENERAL_NAME_value(names, j))
 455          && np->type == GEN_URI
 456          )
 457         list = string_append_listele_n(list, sep,
 458           ASN1_STRING_data(np->d.uniformResourceIdentifier),
 459           ASN1_STRING_length(np->d.uniformResourceIdentifier));
 460     }
 461 sk_DIST_POINT_free(dps);
 462 return string_from_gstring(list);
 463 }
 464
 465
 466
 467 /*****************************************************
 468 *  Certificate operator routines
 469 *****************************************************/
 470 uschar *
 471 tls_cert_der_b64(void * cert)
 472 {
 473 BIO * bp = BIO_new(BIO_s_mem());
 474 uschar * cp = NULL;
 475
 476 if (!i2d_X509_bio(bp, (X509 *)cert))
 477   log_write(0, LOG_MAIN, "TLS error in certificate export: %s",
 478     ERR_error_string(ERR_get_error(), NULL));
 479 else
 480   {
 481   long len = BIO_get_mem_data(bp, &cp);
 482   cp = b64encode(cp, (int)len);
 483   }
 484
 485 BIO_free(bp);
 486 return cp;
 487 }
 488
 489
 490 static uschar *
 491 fingerprint(X509 * cert, const EVP_MD * fdig)
 492 {
 493 int j;
 494 unsigned int n;
 495 uschar md[EVP_MAX_MD_SIZE];
 496 uschar * cp;
 497
 498 if (!X509_digest(cert,fdig,md,&n))
 499   {
 500   expand_string_message = US"tls_cert_fprt: out of mem\n";
 501   return NULL;
 502   }
 503 cp = store_get(n*2+1);
 504 for (j = 0; j < (int)n; j++) sprintf(CS cp+2*j, "%02X", md[j]);
 505 return(cp);
 506 }
 507
 508 uschar *
 509 tls_cert_fprt_md5(void * cert)
 510 {
 511 return fingerprint((X509 *)cert, EVP_md5());
 512 }
 513
 514 uschar *
 515 tls_cert_fprt_sha1(void * cert)
 516 {
 517 return fingerprint((X509 *)cert, EVP_sha1());
 518 }
 519
 520 uschar *
 521 tls_cert_fprt_sha256(void * cert)
 522 {
 523 return fingerprint((X509 *)cert, EVP_sha256());
 524 }
 525
 526
 527 /* vi: aw ai sw=2
 528 */
 529 /* End of tlscert-openssl.c */