src/src/tlscert-openssl.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Jeremy Harris 2014 - 2019 */
   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 #ifdef LIBRESSL_VERSION_NUMBER  /* LibreSSL */
  21 # if LIBRESSL_VERSION_NUMBER >= 0x2090000fL
  22 #  define EXIM_HAVE_ASN1_MACROS
  23 # endif
  24 #else                           /* OpenSSL */
  25 # if OPENSSL_VERSION_NUMBER >= 0x10100000L
  26 #  define EXIM_HAVE_ASN1_MACROS
  27 # endif
  28 #endif
  29
  30 #if OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
  31 # define ASN1_STRING_get0_data ASN1_STRING_data
  32 #endif
  33
  34 /*****************************************************
  35 *  Export/import a certificate, binary/printable
  36 ******************************************************
  37 Return booolean success
  38 */
  39 BOOL
  40 tls_export_cert(uschar * buf, size_t buflen, void * cert)
  41 {
  42 BIO * bp = BIO_new(BIO_s_mem());
  43 BOOL fail;
  44
  45 if ((fail = PEM_write_bio_X509(bp, (X509 *)cert) ? 0 : 1))
  46   log_write(0, LOG_MAIN, "TLS error in certificate export: %s",
  47     ERR_error_string(ERR_get_error(), NULL));
  48 else
  49   {
  50   char * cp = CS buf;
  51   int n;
  52   buflen -= 2;
  53   for(;;)
  54     {
  55     if ((n = BIO_gets(bp, cp, (int)buflen)) <= 0) break;
  56     cp += n+1;
  57     buflen -= n+1;
  58     cp[-2] = '\\'; cp[-1] = 'n'; /* newline->"\n" */
  59     }                            /* compat with string_printing() */
  60   *cp = '\0';
  61   }
  62
  63 BIO_free(bp);
  64 return !fail;
  65 }
  66
  67 /* On error, NULL out the destination */
  68 BOOL
  69 tls_import_cert(const uschar * buf, void ** cert)
  70 {
  71 rmark reset_point = store_mark();
  72 const uschar * cp = string_unprinting(US buf);
  73 BIO * bp;
  74 X509 * x = *(X509 **)cert;
  75
  76 if (x) X509_free(x);
  77
  78 bp = BIO_new_mem_buf(US cp, -1);
  79 if (!(x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
  80   log_write(0, LOG_MAIN, "TLS error in certificate import: %s",
  81     ERR_error_string(ERR_get_error(), NULL));
  82
  83 *cert = (void *)x;
  84 BIO_free(bp);
  85 store_reset(reset_point);
  86 return !!x;
  87 }
  88
  89 void
  90 tls_free_cert(void ** cert)
  91 {
  92 X509 * x = *(X509 **)cert;
  93 if (x)
  94   {
  95   X509_free(x);
  96   *cert = NULL;
  97   }
  98 }
  99
 100
 101 /*****************************************************
 102 *  Certificate field extraction routines
 103 *****************************************************/
 104
 105 /* First, some internal service functions */
 106
 107 static uschar *
 108 badalloc(void)
 109 {
 110 expand_string_message = US"allocation failure";
 111 return NULL;
 112 }
 113
 114 static uschar *
 115 bio_string_copy(BIO * bp, int len)
 116 {
 117 uschar * cp = US"";
 118 len = len > 0 ? (int) BIO_get_mem_data(bp, &cp) : 0;
 119 cp = string_copyn(cp, len);
 120 BIO_free(bp);
 121 return cp;
 122 }
 123
 124 static uschar *
 125 asn1_time_copy(const ASN1_TIME * asntime, uschar * mod)
 126 {
 127 uschar * s = NULL;
 128 BIO * bp = BIO_new(BIO_s_mem());
 129 int len;
 130
 131 if (!bp)
 132   return badalloc();
 133 len = ASN1_TIME_print(bp, asntime);
 134 len = len > 0 ? (int) BIO_get_mem_data(bp, CSS &s) : 0;
 135
 136 if (mod && Ustrcmp(mod, "raw") == 0)            /* native ASN */
 137   s = string_copyn(s, len);
 138 else
 139   {
 140   struct tm tm;
 141   struct tm * tm_p = &tm;
 142   BOOL mod_tz = TRUE;
 143   uschar * tz = to_tz(US"GMT0");    /* need to call strptime with baseline TZ */
 144
 145   /* Parse OpenSSL ASN1_TIME_print output.  A shame there seems to
 146   be no other interface for the times.
 147   */
 148
 149   /*XXX %Z might be glibc-specific?  Solaris has it, at least*/
 150   /*XXX should we switch to POSIX locale for this? */
 151   tm.tm_isdst = 0;
 152   if (!len || !strptime(CCS s, "%b %e %T %Y %Z", &tm))
 153     expand_string_message = US"failed time conversion";
 154
 155   else
 156     {
 157     time_t t = mktime(&tm);     /* make the tm self-consistent */
 158
 159     if (mod && Ustrcmp(mod, "int") == 0)        /* seconds since epoch */
 160       s = string_sprintf(TIME_T_FMT, t);
 161
 162     else
 163       {
 164       if (!f.timestamps_utc)    /* decoded string in local TZ */
 165         {                               /* shift to local TZ */
 166         restore_tz(tz);
 167         mod_tz = FALSE;
 168         tm_p = localtime(&t);
 169         }
 170       /* "utc" is default, and rfc5280 says cert times should be Zulu */
 171
 172       /* convert to string in our format */
 173       len = 32;
 174       s = store_get(len, FALSE);
 175       strftime(CS s, (size_t)len, "%b %e %T %Y %z", tm_p);
 176       }
 177     }
 178
 179   if (mod_tz)
 180     restore_tz(tz);
 181   }
 182 BIO_free(bp);
 183 return s;
 184 }
 185
 186 static uschar *
 187 x509_name_copy(X509_NAME * name)
 188 {
 189 BIO * bp = BIO_new(BIO_s_mem());
 190 int len_good;
 191
 192 if (!bp) return badalloc();
 193
 194 len_good =
 195   X509_NAME_print_ex(bp, name, 0, XN_FLAG_RFC2253) >= 0
 196   ? 1 : 0;
 197 return bio_string_copy(bp, len_good);
 198 }
 199
 200 /**/
 201 /* Now the extractors, called from expand.c
 202 Arguments:
 203   cert          The certificate
 204   mod           Optional modifiers for the operator
 205
 206 Return:
 207   Allocated string with extracted value
 208 */
 209
 210 uschar *
 211 tls_cert_issuer(void * cert, uschar * mod)
 212 {
 213 uschar * cp = x509_name_copy(X509_get_issuer_name((X509 *)cert));
 214 return mod ? tls_field_from_dn(cp, mod) : cp;
 215 }
 216
 217 uschar *
 218 tls_cert_not_before(void * cert, uschar * mod)
 219 {
 220 return asn1_time_copy(X509_get_notBefore((X509 *)cert), mod);
 221 }
 222
 223 uschar *
 224 tls_cert_not_after(void * cert, uschar * mod)
 225 {
 226 return asn1_time_copy(X509_get_notAfter((X509 *)cert), mod);
 227 }
 228
 229 uschar *
 230 tls_cert_serial_number(void * cert, uschar * mod)
 231 {
 232 uschar txt[256];
 233 BIO * bp = BIO_new(BIO_s_mem());
 234 int len;
 235
 236 if (!bp) return badalloc();
 237
 238 len = i2a_ASN1_INTEGER(bp, X509_get_serialNumber((X509 *)cert));
 239 if (len < sizeof(txt))
 240   BIO_read(bp, txt, len);
 241 else
 242   len = 0;
 243 BIO_free(bp);
 244 return string_copynlc(txt, len);        /* lowercase */
 245 }
 246
 247 uschar *
 248 tls_cert_signature(void * cert, uschar * mod)
 249 {
 250 uschar * cp = NULL;
 251 BIO * bp = BIO_new(BIO_s_mem());
 252
 253 if (!bp) return badalloc();
 254
 255 if (X509_print_ex(bp, (X509 *)cert, 0,
 256   X509_FLAG_NO_HEADER | X509_FLAG_NO_VERSION | X509_FLAG_NO_SERIAL |
 257   X509_FLAG_NO_SIGNAME | X509_FLAG_NO_ISSUER | X509_FLAG_NO_VALIDITY |
 258   X509_FLAG_NO_SUBJECT | X509_FLAG_NO_PUBKEY | X509_FLAG_NO_EXTENSIONS |
 259   /* X509_FLAG_NO_SIGDUMP is the missing one */
 260   X509_FLAG_NO_AUX) == 1)
 261   {
 262   long len = BIO_get_mem_data(bp, &cp);
 263
 264   /* Strip leading "Signature Algorithm" line */
 265   while (*cp && *cp != '\n') { cp++; len--; }
 266
 267   cp = string_copyn(cp+1, len-1);
 268   }
 269 BIO_free(bp);
 270 return cp;
 271 }
 272
 273 uschar *
 274 tls_cert_signature_algorithm(void * cert, uschar * mod)
 275 {
 276 uschar * cp = NULL;
 277 BIO * bp = BIO_new(BIO_s_mem());
 278
 279 if (!bp) return badalloc();
 280
 281 if (X509_print_ex(bp, (X509 *)cert, 0,
 282   X509_FLAG_NO_HEADER | X509_FLAG_NO_VERSION | X509_FLAG_NO_SERIAL |
 283   /* X509_FLAG_NO_SIGNAME is the missing one */
 284   X509_FLAG_NO_ISSUER | X509_FLAG_NO_VALIDITY |
 285   X509_FLAG_NO_SUBJECT | X509_FLAG_NO_PUBKEY | X509_FLAG_NO_EXTENSIONS |
 286   X509_FLAG_NO_SIGDUMP | X509_FLAG_NO_AUX) == 1)
 287   {
 288   long len = BIO_get_mem_data(bp, &cp);
 289
 290   /* Strip leading "    Signature Algorithm: " and trailing newline */
 291   while (*cp && *cp != ':') { cp++; len--; }
 292   do { cp++; len--; } while (*cp && *cp == ' ');
 293   if (cp[len-1] == '\n') len--;
 294
 295   cp = string_copyn(cp, len);
 296   }
 297 BIO_free(bp);
 298 return cp;
 299 }
 300
 301 uschar *
 302 tls_cert_subject(void * cert, uschar * mod)
 303 {
 304 uschar * cp = x509_name_copy(X509_get_subject_name((X509 *)cert));
 305 return mod ? tls_field_from_dn(cp, mod) : cp;
 306 }
 307
 308 uschar *
 309 tls_cert_version(void * cert, uschar * mod)
 310 {
 311 return string_sprintf("%ld", X509_get_version((X509 *)cert));
 312 }
 313
 314 uschar *
 315 tls_cert_ext_by_oid(void * cert, uschar * oid, int idx)
 316 {
 317 int nid = OBJ_create(CS oid, "", "");
 318 int nidx = X509_get_ext_by_NID((X509 *)cert, nid, idx);
 319 X509_EXTENSION * ex = X509_get_ext((X509 *)cert, nidx);
 320 ASN1_OCTET_STRING * adata = X509_EXTENSION_get_data(ex);
 321 BIO * bp = BIO_new(BIO_s_mem());
 322 long len;
 323 uschar * cp1;
 324 uschar * cp2;
 325 uschar * cp3;
 326
 327 if (!bp) return badalloc();
 328
 329 #ifdef EXIM_HAVE_ASN1_MACROS
 330 ASN1_STRING_print(bp, adata);
 331 #else
 332 M_ASN1_OCTET_STRING_print(bp, adata);
 333 #endif
 334
 335 /* binary data, DER encoded */
 336 /* just dump for now */
 337 len = BIO_get_mem_data(bp, &cp1);
 338 cp3 = cp2 = store_get(len*3+1, TRUE);
 339
 340 while(len)
 341   {
 342   cp2 += sprintf(CS cp2, "%.2x ", *cp1++);
 343   len--;
 344   }
 345 cp2[-1] = '\0';
 346
 347 return cp3;
 348 }
 349
 350 uschar *
 351 tls_cert_subject_altname(void * cert, uschar * mod)
 352 {
 353 gstring * list = NULL;
 354 STACK_OF(GENERAL_NAME) * san = (STACK_OF(GENERAL_NAME) *)
 355   X509_get_ext_d2i((X509 *)cert, NID_subject_alt_name, NULL, NULL);
 356 uschar osep = '\n';
 357 uschar * tag = US"";
 358 uschar * ele;
 359 int match = -1;
 360 int len;
 361
 362 if (!san) return NULL;
 363
 364 while (mod && *mod)
 365   {
 366   if (*mod == '>' && *++mod) osep = *mod++;
 367   else if (Ustrncmp(mod,"dns",3)==0) { match = GEN_DNS; mod += 3; }
 368   else if (Ustrncmp(mod,"uri",3)==0) { match = GEN_URI; mod += 3; }
 369   else if (Ustrncmp(mod,"mail",4)==0) { match = GEN_EMAIL; mod += 4; }
 370   else mod++;
 371
 372   if (*mod == ',') mod++;
 373   }
 374
 375 while (sk_GENERAL_NAME_num(san) > 0)
 376   {
 377   GENERAL_NAME * namePart = sk_GENERAL_NAME_pop(san);
 378   if (match != -1 && match != namePart->type)
 379     continue;
 380   switch (namePart->type)
 381     {
 382     case GEN_DNS:
 383       tag = US"DNS";
 384       ele = US ASN1_STRING_get0_data(namePart->d.dNSName);
 385       len = ASN1_STRING_length(namePart->d.dNSName);
 386       break;
 387     case GEN_URI:
 388       tag = US"URI";
 389       ele = US ASN1_STRING_get0_data(namePart->d.uniformResourceIdentifier);
 390       len = ASN1_STRING_length(namePart->d.uniformResourceIdentifier);
 391       break;
 392     case GEN_EMAIL:
 393       tag = US"MAIL";
 394       ele = US ASN1_STRING_get0_data(namePart->d.rfc822Name);
 395       len = ASN1_STRING_length(namePart->d.rfc822Name);
 396       break;
 397     default:
 398       continue; /* ignore unrecognised types */
 399     }
 400   if (ele[len]) /* not nul-terminated */
 401     ele = string_copyn(ele, len);
 402
 403   if (Ustrlen(ele) == len)      /* ignore any with embedded nul */
 404     list = string_append_listele(list, osep,
 405           match == -1 ? string_sprintf("%s=%s", tag, ele) : ele);
 406   }
 407
 408 sk_GENERAL_NAME_free(san);
 409 return string_from_gstring(list);
 410 }
 411
 412 uschar *
 413 tls_cert_ocsp_uri(void * cert, uschar * mod)
 414 {
 415 STACK_OF(ACCESS_DESCRIPTION) * ads = (STACK_OF(ACCESS_DESCRIPTION) *)
 416   X509_get_ext_d2i((X509 *)cert, NID_info_access, NULL, NULL);
 417 int adsnum = sk_ACCESS_DESCRIPTION_num(ads);
 418 uschar sep = '\n';
 419 gstring * list = NULL;
 420
 421 if (mod)
 422   if (*mod == '>' && *++mod) sep = *mod++;
 423
 424 for (int i = 0; i < adsnum; i++)
 425   {
 426   ACCESS_DESCRIPTION * ad = sk_ACCESS_DESCRIPTION_value(ads, i);
 427
 428   if (ad && OBJ_obj2nid(ad->method) == NID_ad_OCSP)
 429     list = string_append_listele_n(list, sep,
 430       US ASN1_STRING_get0_data(ad->location->d.ia5),
 431       ASN1_STRING_length(ad->location->d.ia5));
 432   }
 433 sk_ACCESS_DESCRIPTION_free(ads);
 434 return string_from_gstring(list);
 435 }
 436
 437 uschar *
 438 tls_cert_crl_uri(void * cert, uschar * mod)
 439 {
 440 STACK_OF(DIST_POINT) * dps = (STACK_OF(DIST_POINT) *)
 441   X509_get_ext_d2i((X509 *)cert,  NID_crl_distribution_points,
 442     NULL, NULL);
 443 DIST_POINT * dp;
 444 uschar sep = '\n';
 445 gstring * list = NULL;
 446
 447 if (mod)
 448   if (*mod == '>' && *++mod) sep = *mod++;
 449
 450 if (dps) for (int i = 0, dpsnum = sk_DIST_POINT_num(dps); i < dpsnum; i++)
 451   if ((dp = sk_DIST_POINT_value(dps, i)))
 452     {
 453     STACK_OF(GENERAL_NAME) * names = dp->distpoint->name.fullname;
 454     GENERAL_NAME * np;
 455
 456     for (int j = 0, nnum = sk_GENERAL_NAME_num(names); j < nnum; j++)
 457       if (  (np = sk_GENERAL_NAME_value(names, j))
 458          && np->type == GEN_URI
 459          )
 460         list = string_append_listele_n(list, sep,
 461           US ASN1_STRING_get0_data(np->d.uniformResourceIdentifier),
 462           ASN1_STRING_length(np->d.uniformResourceIdentifier));
 463     }
 464 sk_DIST_POINT_free(dps);
 465 return string_from_gstring(list);
 466 }
 467
 468
 469
 470 /*****************************************************
 471 *  Certificate operator routines
 472 *****************************************************/
 473 uschar *
 474 tls_cert_der_b64(void * cert)
 475 {
 476 BIO * bp = BIO_new(BIO_s_mem());
 477 uschar * cp = NULL;
 478
 479 if (!i2d_X509_bio(bp, (X509 *)cert))
 480   log_write(0, LOG_MAIN, "TLS error in certificate export: %s",
 481     ERR_error_string(ERR_get_error(), NULL));
 482 else
 483   {
 484   long len = BIO_get_mem_data(bp, &cp);
 485   cp = b64encode(CUS cp, (int)len);
 486   }
 487
 488 BIO_free(bp);
 489 return cp;
 490 }
 491
 492
 493 static uschar *
 494 fingerprint(X509 * cert, const EVP_MD * fdig)
 495 {
 496 unsigned int n;
 497 uschar md[EVP_MAX_MD_SIZE];
 498 uschar * cp;
 499
 500 if (!X509_digest(cert,fdig,md,&n))
 501   {
 502   expand_string_message = US"tls_cert_fprt: out of mem\n";
 503   return NULL;
 504   }
 505 cp = store_get(n*2+1, TRUE);
 506 for (int j = 0; j < (int)n; j++) sprintf(CS cp+2*j, "%02X", md[j]);
 507 return(cp);
 508 }
 509
 510 uschar *
 511 tls_cert_fprt_md5(void * cert)
 512 {
 513 return fingerprint((X509 *)cert, EVP_md5());
 514 }
 515
 516 uschar *
 517 tls_cert_fprt_sha1(void * cert)
 518 {
 519 return fingerprint((X509 *)cert, EVP_sha1());
 520 }
 521
 522 uschar *
 523 tls_cert_fprt_sha256(void * cert)
 524 {
 525 return fingerprint((X509 *)cert, EVP_sha256());
 526 }
 527
 528
 529 /* vi: aw ai sw=2
 530 */
 531 /* End of tlscert-openssl.c */