src/tlscert-openssl.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Jeremy Harris 2014 - 2018 */
   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 #if OPENSSL_VERSION_NUMBER < 0x10100000L || defined(LIBRESSL_VERSION_NUMBER)
  25 # define ASN1_STRING_get0_data ASN1_STRING_data
  26 #endif
  27
  28 /*****************************************************
  29 *  Export/import a certificate, binary/printable
  30 *****************************************************/
  31 int
  32 tls_export_cert(uschar * buf, size_t buflen, void * cert)
  33 {
  34 BIO * bp = BIO_new(BIO_s_mem());
  35 int fail;
  36
  37 if ((fail = PEM_write_bio_X509(bp, (X509 *)cert) ? 0 : 1))
  38   log_write(0, LOG_MAIN, "TLS error in certificate export: %s",
  39     ERR_error_string(ERR_get_error(), NULL));
  40 else
  41   {
  42   char * cp = CS buf;
  43   int n;
  44   buflen -= 2;
  45   for(;;)
  46     {
  47     if ((n = BIO_gets(bp, cp, (int)buflen)) <= 0) break;
  48     cp += n+1;
  49     buflen -= n+1;
  50     cp[-2] = '\\'; cp[-1] = 'n'; /* newline->"\n" */
  51     }                            /* compat with string_printing() */
  52   *cp = '\0';
  53   }
  54
  55 BIO_free(bp);
  56 return fail;
  57 }
  58
  59 int
  60 tls_import_cert(const uschar * buf, void ** cert)
  61 {
  62 void * reset_point = store_get(0);
  63 const uschar * cp = string_unprinting(US buf);
  64 BIO * bp;
  65 X509 * x = *(X509 **)cert;
  66 int fail = 0;
  67
  68 if (x) X509_free(x);
  69
  70 bp = BIO_new_mem_buf(US cp, -1);
  71 if (!(x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
  72   {
  73   log_write(0, LOG_MAIN, "TLS error in certificate import: %s",
  74     ERR_error_string(ERR_get_error(), NULL));
  75   fail = 1;
  76   }
  77 else
  78   *cert = (void *)x;
  79 BIO_free(bp);
  80 store_reset(reset_point);
  81 return fail;
  82 }
  83
  84 void
  85 tls_free_cert(void ** cert)
  86 {
  87 X509 * x = *(X509 **)cert;
  88 if (x)
  89   {
  90   X509_free(x);
  91   *cert = NULL;
  92   }
  93 }
  94
  95
  96 /*****************************************************
  97 *  Certificate field extraction routines
  98 *****************************************************/
  99
 100 /* First, some internal service functions */
 101
 102 static uschar *
 103 badalloc(void)
 104 {
 105 expand_string_message = US"allocation failure";
 106 return NULL;
 107 }
 108
 109 static uschar *
 110 bio_string_copy(BIO * bp, int len)
 111 {
 112 uschar * cp = US"";
 113 len = len > 0 ? (int) BIO_get_mem_data(bp, &cp) : 0;
 114 cp = string_copyn(cp, len);
 115 BIO_free(bp);
 116 return cp;
 117 }
 118
 119 static uschar *
 120 asn1_time_copy(const ASN1_TIME * asntime, uschar * mod)
 121 {
 122 uschar * s = NULL;
 123 BIO * bp = BIO_new(BIO_s_mem());
 124 int len;
 125
 126 if (!bp)
 127   return badalloc();
 128 len = ASN1_TIME_print(bp, asntime);
 129 len = len > 0 ? (int) BIO_get_mem_data(bp, CSS &s) : 0;
 130
 131 if (mod && Ustrcmp(mod, "raw") == 0)            /* native ASN */
 132   s = string_copyn(s, len);
 133 else
 134   {
 135   struct tm tm;
 136   struct tm * tm_p = &tm;
 137   BOOL mod_tz = TRUE;
 138   uschar * tz = to_tz(US"GMT0");    /* need to call strptime with baseline TZ */
 139
 140   /* Parse OpenSSL ASN1_TIME_print output.  A shame there seems to
 141   be no other interface for the times.
 142   */
 143
 144   /*XXX %Z might be glibc-specific?  Solaris has it, at least*/
 145   /*XXX should we switch to POSIX locale for this? */
 146   tm.tm_isdst = 0;
 147   if (!len || !strptime(CCS s, "%b %e %T %Y %Z", &tm))
 148     expand_string_message = US"failed time conversion";
 149
 150   else
 151     {
 152     time_t t = mktime(&tm);     /* make the tm self-consistent */
 153
 154     if (mod && Ustrcmp(mod, "int") == 0)        /* seconds since epoch */
 155       s = string_sprintf(TIME_T_FMT, t);
 156
 157     else
 158       {
 159       if (!f.timestamps_utc)    /* decoded string in local TZ */
 160         {                               /* shift to local TZ */
 161         restore_tz(tz);
 162         mod_tz = FALSE;
 163         tm_p = localtime(&t);
 164         }
 165       /* "utc" is default, and rfc5280 says cert times should be Zulu */
 166
 167       /* convert to string in our format */
 168       len = 32;
 169       s = store_get(len);
 170       strftime(CS s, (size_t)len, "%b %e %T %Y %z", tm_p);
 171       }
 172     }
 173
 174   if (mod_tz)
 175     restore_tz(tz);
 176   }
 177 BIO_free(bp);
 178 return s;
 179 }
 180
 181 static uschar *
 182 x509_name_copy(X509_NAME * name)
 183 {
 184 BIO * bp = BIO_new(BIO_s_mem());
 185 int len_good;
 186
 187 if (!bp) return badalloc();
 188
 189 len_good =
 190   X509_NAME_print_ex(bp, name, 0, XN_FLAG_RFC2253) >= 0
 191   ? 1 : 0;
 192 return bio_string_copy(bp, len_good);
 193 }
 194
 195 /**/
 196 /* Now the extractors, called from expand.c
 197 Arguments:
 198   cert          The certificate
 199   mod           Optional modifiers for the operator
 200
 201 Return:
 202   Allocated string with extracted value
 203 */
 204
 205 uschar *
 206 tls_cert_issuer(void * cert, uschar * mod)
 207 {
 208 uschar * cp = x509_name_copy(X509_get_issuer_name((X509 *)cert));
 209 return mod ? tls_field_from_dn(cp, mod) : cp;
 210 }
 211
 212 uschar *
 213 tls_cert_not_before(void * cert, uschar * mod)
 214 {
 215 return asn1_time_copy(X509_get_notBefore((X509 *)cert), mod);
 216 }
 217
 218 uschar *
 219 tls_cert_not_after(void * cert, uschar * mod)
 220 {
 221 return asn1_time_copy(X509_get_notAfter((X509 *)cert), mod);
 222 }
 223
 224 uschar *
 225 tls_cert_serial_number(void * cert, uschar * mod)
 226 {
 227 uschar txt[256];
 228 BIO * bp = BIO_new(BIO_s_mem());
 229 int len;
 230
 231 if (!bp) return badalloc();
 232
 233 len = i2a_ASN1_INTEGER(bp, X509_get_serialNumber((X509 *)cert));
 234 if (len < sizeof(txt))
 235   BIO_read(bp, txt, len);
 236 else
 237   len = 0;
 238 BIO_free(bp);
 239 return string_copynlc(txt, len);        /* lowercase */
 240 }
 241
 242 uschar *
 243 tls_cert_signature(void * cert, uschar * mod)
 244 {
 245 uschar * cp = NULL;
 246 BIO * bp = BIO_new(BIO_s_mem());
 247
 248 if (!bp) return badalloc();
 249
 250 if (X509_print_ex(bp, (X509 *)cert, 0,
 251   X509_FLAG_NO_HEADER | X509_FLAG_NO_VERSION | X509_FLAG_NO_SERIAL |
 252   X509_FLAG_NO_SIGNAME | X509_FLAG_NO_ISSUER | X509_FLAG_NO_VALIDITY |
 253   X509_FLAG_NO_SUBJECT | X509_FLAG_NO_PUBKEY | X509_FLAG_NO_EXTENSIONS |
 254   /* X509_FLAG_NO_SIGDUMP is the missing one */
 255   X509_FLAG_NO_AUX) == 1)
 256   {
 257   long len = BIO_get_mem_data(bp, &cp);
 258
 259   /* Strip leading "Signature Algorithm" line */
 260   while (*cp && *cp != '\n') { cp++; len--; }
 261
 262   cp = string_copyn(cp+1, len-1);
 263   }
 264 BIO_free(bp);
 265 return cp;
 266 }
 267
 268 uschar *
 269 tls_cert_signature_algorithm(void * cert, uschar * mod)
 270 {
 271 uschar * cp = NULL;
 272 BIO * bp = BIO_new(BIO_s_mem());
 273
 274 if (!bp) return badalloc();
 275
 276 if (X509_print_ex(bp, (X509 *)cert, 0,
 277   X509_FLAG_NO_HEADER | X509_FLAG_NO_VERSION | X509_FLAG_NO_SERIAL |
 278   /* X509_FLAG_NO_SIGNAME is the missing one */
 279   X509_FLAG_NO_ISSUER | X509_FLAG_NO_VALIDITY |
 280   X509_FLAG_NO_SUBJECT | X509_FLAG_NO_PUBKEY | X509_FLAG_NO_EXTENSIONS |
 281   X509_FLAG_NO_SIGDUMP | X509_FLAG_NO_AUX) == 1)
 282   {
 283   long len = BIO_get_mem_data(bp, &cp);
 284
 285   /* Strip leading "    Signature Algorithm: " and trailing newline */
 286   while (*cp && *cp != ':') { cp++; len--; }
 287   do { cp++; len--; } while (*cp && *cp == ' ');
 288   if (cp[len-1] == '\n') len--;
 289
 290   cp = string_copyn(cp, len);
 291   }
 292 BIO_free(bp);
 293 return cp;
 294 }
 295
 296 uschar *
 297 tls_cert_subject(void * cert, uschar * mod)
 298 {
 299 uschar * cp = x509_name_copy(X509_get_subject_name((X509 *)cert));
 300 return mod ? tls_field_from_dn(cp, mod) : cp;
 301 }
 302
 303 uschar *
 304 tls_cert_version(void * cert, uschar * mod)
 305 {
 306 return string_sprintf("%ld", X509_get_version((X509 *)cert));
 307 }
 308
 309 uschar *
 310 tls_cert_ext_by_oid(void * cert, uschar * oid, int idx)
 311 {
 312 int nid = OBJ_create(CS oid, "", "");
 313 int nidx = X509_get_ext_by_NID((X509 *)cert, nid, idx);
 314 X509_EXTENSION * ex = X509_get_ext((X509 *)cert, nidx);
 315 ASN1_OCTET_STRING * adata = X509_EXTENSION_get_data(ex);
 316 BIO * bp = BIO_new(BIO_s_mem());
 317 long len;
 318 uschar * cp1;
 319 uschar * cp2;
 320 uschar * cp3;
 321
 322 if (!bp) return badalloc();
 323
 324 #ifdef EXIM_HAVE_ASN1_MACROS
 325 ASN1_STRING_print(bp, adata);
 326 #else
 327 M_ASN1_OCTET_STRING_print(bp, adata);
 328 #endif
 329
 330 /* binary data, DER encoded */
 331 /* just dump for now */
 332 len = BIO_get_mem_data(bp, &cp1);
 333 cp3 = cp2 = store_get(len*3+1);
 334
 335 while(len)
 336   {
 337   cp2 += sprintf(CS cp2, "%.2x ", *cp1++);
 338   len--;
 339   }
 340 cp2[-1] = '\0';
 341
 342 return cp3;
 343 }
 344
 345 uschar *
 346 tls_cert_subject_altname(void * cert, uschar * mod)
 347 {
 348 gstring * list = NULL;
 349 STACK_OF(GENERAL_NAME) * san = (STACK_OF(GENERAL_NAME) *)
 350   X509_get_ext_d2i((X509 *)cert, NID_subject_alt_name, NULL, NULL);
 351 uschar osep = '\n';
 352 uschar * tag = US"";
 353 uschar * ele;
 354 int match = -1;
 355 int len;
 356
 357 if (!san) return NULL;
 358
 359 while (mod && *mod)
 360   {
 361   if (*mod == '>' && *++mod) osep = *mod++;
 362   else if (Ustrncmp(mod,"dns",3)==0) { match = GEN_DNS; mod += 3; }
 363   else if (Ustrncmp(mod,"uri",3)==0) { match = GEN_URI; mod += 3; }
 364   else if (Ustrncmp(mod,"mail",4)==0) { match = GEN_EMAIL; mod += 4; }
 365   else mod++;
 366
 367   if (*mod == ',') mod++;
 368   }
 369
 370 while (sk_GENERAL_NAME_num(san) > 0)
 371   {
 372   GENERAL_NAME * namePart = sk_GENERAL_NAME_pop(san);
 373   if (match != -1 && match != namePart->type)
 374     continue;
 375   switch (namePart->type)
 376     {
 377     case GEN_DNS:
 378       tag = US"DNS";
 379       ele = US ASN1_STRING_get0_data(namePart->d.dNSName);
 380       len = ASN1_STRING_length(namePart->d.dNSName);
 381       break;
 382     case GEN_URI:
 383       tag = US"URI";
 384       ele = US ASN1_STRING_get0_data(namePart->d.uniformResourceIdentifier);
 385       len = ASN1_STRING_length(namePart->d.uniformResourceIdentifier);
 386       break;
 387     case GEN_EMAIL:
 388       tag = US"MAIL";
 389       ele = US ASN1_STRING_get0_data(namePart->d.rfc822Name);
 390       len = ASN1_STRING_length(namePart->d.rfc822Name);
 391       break;
 392     default:
 393       continue; /* ignore unrecognised types */
 394     }
 395   if (ele[len]) /* not nul-terminated */
 396     ele = string_copyn(ele, len);
 397
 398   if (Ustrlen(ele) == len)      /* ignore any with embedded nul */
 399     list = string_append_listele(list, osep,
 400           match == -1 ? string_sprintf("%s=%s", tag, ele) : ele);
 401   }
 402
 403 sk_GENERAL_NAME_free(san);
 404 return string_from_gstring(list);
 405 }
 406
 407 uschar *
 408 tls_cert_ocsp_uri(void * cert, uschar * mod)
 409 {
 410 STACK_OF(ACCESS_DESCRIPTION) * ads = (STACK_OF(ACCESS_DESCRIPTION) *)
 411   X509_get_ext_d2i((X509 *)cert, NID_info_access, NULL, NULL);
 412 int adsnum = sk_ACCESS_DESCRIPTION_num(ads);
 413 int i;
 414 uschar sep = '\n';
 415 gstring * list = NULL;
 416
 417 if (mod)
 418   if (*mod == '>' && *++mod) sep = *mod++;
 419
 420 for (i = 0; i < adsnum; i++)
 421   {
 422   ACCESS_DESCRIPTION * ad = sk_ACCESS_DESCRIPTION_value(ads, i);
 423
 424   if (ad && OBJ_obj2nid(ad->method) == NID_ad_OCSP)
 425     list = string_append_listele_n(list, sep,
 426       US ASN1_STRING_get0_data(ad->location->d.ia5),
 427       ASN1_STRING_length(ad->location->d.ia5));
 428   }
 429 sk_ACCESS_DESCRIPTION_free(ads);
 430 return string_from_gstring(list);
 431 }
 432
 433 uschar *
 434 tls_cert_crl_uri(void * cert, uschar * mod)
 435 {
 436 STACK_OF(DIST_POINT) * dps = (STACK_OF(DIST_POINT) *)
 437   X509_get_ext_d2i((X509 *)cert,  NID_crl_distribution_points,
 438     NULL, NULL);
 439 DIST_POINT * dp;
 440 int dpsnum = sk_DIST_POINT_num(dps);
 441 int i;
 442 uschar sep = '\n';
 443 gstring * list = NULL;
 444
 445 if (mod)
 446   if (*mod == '>' && *++mod) sep = *mod++;
 447
 448 if (dps) for (i = 0; i < dpsnum; i++)
 449   if ((dp = sk_DIST_POINT_value(dps, i)))
 450     {
 451     STACK_OF(GENERAL_NAME) * names = dp->distpoint->name.fullname;
 452     GENERAL_NAME * np;
 453     int nnum = sk_GENERAL_NAME_num(names);
 454     int j;
 455
 456     for (j = 0; 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(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 int j;
 497 unsigned int n;
 498 uschar md[EVP_MAX_MD_SIZE];
 499 uschar * cp;
 500
 501 if (!X509_digest(cert,fdig,md,&n))
 502   {
 503   expand_string_message = US"tls_cert_fprt: out of mem\n";
 504   return NULL;
 505   }
 506 cp = store_get(n*2+1);
 507 for (j = 0; j < (int)n; j++) sprintf(CS cp+2*j, "%02X", md[j]);
 508 return(cp);
 509 }
 510
 511 uschar *
 512 tls_cert_fprt_md5(void * cert)
 513 {
 514 return fingerprint((X509 *)cert, EVP_md5());
 515 }
 516
 517 uschar *
 518 tls_cert_fprt_sha1(void * cert)
 519 {
 520 return fingerprint((X509 *)cert, EVP_sha1());
 521 }
 522
 523 uschar *
 524 tls_cert_fprt_sha256(void * cert)
 525 {
 526 return fingerprint((X509 *)cert, EVP_sha256());
 527 }
 528
 529
 530 /* vi: aw ai sw=2
 531 */
 532 /* End of tlscert-openssl.c */