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