src/src/tlscert-openssl.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Jeremy Harris 2014 - 2015 */
   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
  21 /*****************************************************
  22 *  Export/import a certificate, binary/printable
  23 *****************************************************/
  24 int
  25 tls_export_cert(uschar * buf, size_t buflen, void * cert)
  26 {
  27 BIO * bp = BIO_new(BIO_s_mem());
  28 int fail;
  29
  30 if ((fail = PEM_write_bio_X509(bp, (X509 *)cert) ? 0 : 1))
  31   log_write(0, LOG_MAIN, "TLS error in certificate export: %s",
  32     ERR_error_string(ERR_get_error(), NULL));
  33 else
  34   {
  35   char * cp = CS buf;
  36   int n;
  37   buflen -= 2;
  38   for(;;)
  39     {
  40     if ((n = BIO_gets(bp, cp, (int)buflen)) <= 0) break;
  41     cp += n+1;
  42     buflen -= n+1;
  43     cp[-2] = '\\'; cp[-1] = 'n'; /* newline->"\n" */
  44     }                            /* compat with string_printing() */
  45   *cp = '\0';
  46   }
  47
  48 BIO_free(bp);
  49 return fail;
  50 }
  51
  52 int
  53 tls_import_cert(const uschar * buf, void ** cert)
  54 {
  55 void * reset_point = store_get(0);
  56 const uschar * cp = string_unprinting(US buf);
  57 BIO * bp;
  58 X509 * x = *(X509 **)cert;
  59 int fail = 0;
  60
  61 if (x) X509_free(x);
  62
  63 bp = BIO_new_mem_buf(US cp, -1);
  64 if (!(x = PEM_read_bio_X509(bp, NULL, 0, NULL)))
  65   {
  66   log_write(0, LOG_MAIN, "TLS error in certificate import: %s",
  67     ERR_error_string(ERR_get_error(), NULL));
  68   fail = 1;
  69   }
  70 else
  71   *cert = (void *)x;
  72 BIO_free(bp);
  73 store_reset(reset_point);
  74 return fail;
  75 }
  76
  77 void
  78 tls_free_cert(void ** cert)
  79 {
  80 X509 * x = *(X509 **)cert;
  81 if (x)
  82   {
  83   X509_free(x);
  84   *cert = NULL;
  85   }
  86 }
  87
  88
  89 /*****************************************************
  90 *  Certificate field extraction routines
  91 *****************************************************/
  92
  93 /* First, some internal service functions */
  94
  95 static uschar *
  96 badalloc(void)
  97 {
  98 expand_string_message = US"allocation failure";
  99 return NULL;
 100 }
 101
 102 static uschar *
 103 bio_string_copy(BIO * bp, int len)
 104 {
 105 uschar * cp = US"";
 106 len = len > 0 ? (int) BIO_get_mem_data(bp, &cp) : 0;
 107 cp = string_copyn(cp, len);
 108 BIO_free(bp);
 109 return cp;
 110 }
 111
 112 static uschar *
 113 asn1_time_copy(const ASN1_TIME * asntime, uschar * mod)
 114 {
 115 uschar * s = NULL;
 116 BIO * bp = BIO_new(BIO_s_mem());
 117 int len;
 118
 119 if (!bp)
 120   return badalloc();
 121 len = ASN1_TIME_print(bp, asntime);
 122 len = len > 0 ? (int) BIO_get_mem_data(bp, &s) : 0;
 123
 124 if (mod && Ustrcmp(mod, "raw") == 0)            /* native ASN */
 125   s = string_copyn(s, len);
 126 else
 127   {
 128   struct tm tm;
 129   struct tm * tm_p = &tm;
 130   BOOL mod_tz = TRUE;
 131   uschar * tz = to_tz(US"GMT0");    /* need to call strptime with baseline TZ */
 132
 133   /* Parse OpenSSL ASN1_TIME_print output.  A shame there seems to
 134   be no other interface for the times.
 135   */
 136
 137   /*XXX %Z might be glibc-specific?  Solaris has it, at least*/
 138   /*XXX should we switch to POSIX locale for this? */
 139   tm.tm_isdst = 0;
 140   if (!strptime(CCS s, "%b %e %T %Y %Z", &tm))
 141     expand_string_message = US"failed time conversion";
 142
 143   else
 144     {
 145     time_t t = mktime(&tm);     /* make the tm self-consistent */
 146
 147     if (mod && Ustrcmp(mod, "int") == 0)        /* seconds since epoch */
 148       s = string_sprintf("%u", t);
 149
 150     else
 151       {
 152       if (!timestamps_utc)      /* decoded string in local TZ */
 153         {                               /* shift to local TZ */
 154         restore_tz(tz);
 155         mod_tz = FALSE;
 156         tm_p = localtime(&t);
 157         }
 158       /* "utc" is default, and rfc5280 says cert times should be Zulu */
 159
 160       /* convert to string in our format */
 161       len = 32;
 162       s = store_get(len);
 163       strftime(CS s, (size_t)len, "%b %e %T %Y %z", tm_p);
 164       }
 165     }
 166
 167   if (mod_tz)
 168     restore_tz(tz);
 169   }
 170 BIO_free(bp);
 171 return s;
 172 }
 173
 174 static uschar *
 175 x509_name_copy(X509_NAME * name)
 176 {
 177 BIO * bp = BIO_new(BIO_s_mem());
 178 int len_good;
 179
 180 if (!bp) return badalloc();
 181
 182 len_good =
 183   X509_NAME_print_ex(bp, name, 0, XN_FLAG_RFC2253) >= 0
 184   ? 1 : 0;
 185 return bio_string_copy(bp, len_good);
 186 }
 187
 188 /**/
 189 /* Now the extractors, called from expand.c
 190 Arguments:
 191   cert          The certificate
 192   mod           Optional modifiers for the operator
 193
 194 Return:
 195   Allocated string with extracted value
 196 */
 197
 198 uschar *
 199 tls_cert_issuer(void * cert, uschar * mod)
 200 {
 201 uschar * cp = x509_name_copy(X509_get_issuer_name((X509 *)cert));
 202 return mod ? tls_field_from_dn(cp, mod) : cp;
 203 }
 204
 205 uschar *
 206 tls_cert_not_before(void * cert, uschar * mod)
 207 {
 208 return asn1_time_copy(X509_get_notBefore((X509 *)cert), mod);
 209 }
 210
 211 uschar *
 212 tls_cert_not_after(void * cert, uschar * mod)
 213 {
 214 return asn1_time_copy(X509_get_notAfter((X509 *)cert), mod);
 215 }
 216
 217 uschar *
 218 tls_cert_serial_number(void * cert, uschar * mod)
 219 {
 220 uschar txt[256];
 221 BIO * bp = BIO_new(BIO_s_mem());
 222 int len;
 223
 224 if (!bp) return badalloc();
 225
 226 len = i2a_ASN1_INTEGER(bp, X509_get_serialNumber((X509 *)cert));
 227 if (len < sizeof(txt))
 228   BIO_read(bp, txt, len);
 229 else
 230   len = 0;
 231 BIO_free(bp);
 232 return string_copynlc(txt, len);        /* lowercase */
 233 }
 234
 235 uschar *
 236 tls_cert_signature(void * cert, uschar * mod)
 237 {
 238 uschar * cp = NULL;
 239 BIO * bp = BIO_new(BIO_s_mem());
 240
 241 if (!bp) return badalloc();
 242
 243 if (X509_print_ex(bp, (X509 *)cert, 0,
 244   X509_FLAG_NO_HEADER | X509_FLAG_NO_VERSION | X509_FLAG_NO_SERIAL |
 245   X509_FLAG_NO_SIGNAME | X509_FLAG_NO_ISSUER | X509_FLAG_NO_VALIDITY |
 246   X509_FLAG_NO_SUBJECT | X509_FLAG_NO_PUBKEY | X509_FLAG_NO_EXTENSIONS |
 247   /* X509_FLAG_NO_SIGDUMP is the missing one */
 248   X509_FLAG_NO_AUX) == 1)
 249   {
 250   long len = BIO_get_mem_data(bp, &cp);
 251
 252   /* Strip leading "Signature Algorithm" line */
 253   while (*cp && *cp != '\n') { cp++; len--; }
 254
 255   cp = string_copyn(cp+1, len-1);
 256   }
 257 BIO_free(bp);
 258 return cp;
 259 }
 260
 261 uschar *
 262 tls_cert_signature_algorithm(void * cert, uschar * mod)
 263 {
 264 uschar * cp = NULL;
 265 BIO * bp = BIO_new(BIO_s_mem());
 266
 267 if (!bp) return badalloc();
 268
 269 if (X509_print_ex(bp, (X509 *)cert, 0,
 270   X509_FLAG_NO_HEADER | X509_FLAG_NO_VERSION | X509_FLAG_NO_SERIAL |
 271   /* X509_FLAG_NO_SIGNAME is the missing one */
 272   X509_FLAG_NO_ISSUER | X509_FLAG_NO_VALIDITY |
 273   X509_FLAG_NO_SUBJECT | X509_FLAG_NO_PUBKEY | X509_FLAG_NO_EXTENSIONS |
 274   X509_FLAG_NO_SIGDUMP | X509_FLAG_NO_AUX) == 1)
 275   {
 276   long len = BIO_get_mem_data(bp, &cp);
 277
 278   /* Strip leading "    Signature Algorithm: " and trailing newline */
 279   while (*cp && *cp != ':') { cp++; len--; }
 280   do { cp++; len--; } while (*cp && *cp == ' ');
 281   if (cp[len-1] == '\n') len--;
 282
 283   cp = string_copyn(cp, len);
 284   }
 285 BIO_free(bp);
 286 return cp;
 287 }
 288
 289 uschar *
 290 tls_cert_subject(void * cert, uschar * mod)
 291 {
 292 uschar * cp = x509_name_copy(X509_get_subject_name((X509 *)cert));
 293 return mod ? tls_field_from_dn(cp, mod) : cp;
 294 }
 295
 296 uschar *
 297 tls_cert_version(void * cert, uschar * mod)
 298 {
 299 return string_sprintf("%d", X509_get_version((X509 *)cert));
 300 }
 301
 302 uschar *
 303 tls_cert_ext_by_oid(void * cert, uschar * oid, int idx)
 304 {
 305 int nid = OBJ_create(CS oid, "", "");
 306 int nidx = X509_get_ext_by_NID((X509 *)cert, nid, idx);
 307 X509_EXTENSION * ex = X509_get_ext((X509 *)cert, nidx);
 308 ASN1_OCTET_STRING * adata = X509_EXTENSION_get_data(ex);
 309 BIO * bp = BIO_new(BIO_s_mem());
 310 long len;
 311 uschar * cp1;
 312 uschar * cp2;
 313 uschar * cp3;
 314
 315 if (!bp) return badalloc();
 316
 317 M_ASN1_OCTET_STRING_print(bp, adata);
 318 /* binary data, DER encoded */
 319
 320 /* just dump for now */
 321 len = BIO_get_mem_data(bp, &cp1);
 322 cp3 = cp2 = store_get(len*3+1);
 323
 324 while(len)
 325   {
 326   sprintf(CS cp2, "%.2x ", *cp1++);
 327   cp2 += 3;
 328   len--;
 329   }
 330 cp2[-1] = '\0';
 331
 332 return cp3;
 333 }
 334
 335 uschar *
 336 tls_cert_subject_altname(void * cert, uschar * mod)
 337 {
 338 uschar * list = NULL;
 339 STACK_OF(GENERAL_NAME) * san = (STACK_OF(GENERAL_NAME) *)
 340   X509_get_ext_d2i((X509 *)cert, NID_subject_alt_name, NULL, NULL);
 341 uschar osep = '\n';
 342 uschar * tag = US"";
 343 uschar * ele;
 344 int match = -1;
 345 int len;
 346
 347 if (!san) return NULL;
 348
 349 while (mod && *mod)
 350   {
 351   if (*mod == '>' && *++mod) osep = *mod++;
 352   else if (Ustrncmp(mod,"dns",3)==0) { match = GEN_DNS; mod += 3; }
 353   else if (Ustrncmp(mod,"uri",3)==0) { match = GEN_URI; mod += 3; }
 354   else if (Ustrncmp(mod,"mail",4)==0) { match = GEN_EMAIL; mod += 4; }
 355   else mod++;
 356
 357   if (*mod == ',') mod++;
 358   }
 359
 360 while (sk_GENERAL_NAME_num(san) > 0)
 361   {
 362   GENERAL_NAME * namePart = sk_GENERAL_NAME_pop(san);
 363   if (match != -1 && match != namePart->type)
 364     continue;
 365   switch (namePart->type)
 366     {
 367     case GEN_DNS:
 368       tag = US"DNS";
 369       ele = ASN1_STRING_data(namePart->d.dNSName);
 370       len = ASN1_STRING_length(namePart->d.dNSName);
 371       break;
 372     case GEN_URI:
 373       tag = US"URI";
 374       ele = ASN1_STRING_data(namePart->d.uniformResourceIdentifier);
 375       len = ASN1_STRING_length(namePart->d.uniformResourceIdentifier);
 376       break;
 377     case GEN_EMAIL:
 378       tag = US"MAIL";
 379       ele = ASN1_STRING_data(namePart->d.rfc822Name);
 380       len = ASN1_STRING_length(namePart->d.rfc822Name);
 381       break;
 382     default:
 383       continue; /* ignore unrecognised types */
 384     }
 385   if (ele[len]) /* not nul-terminated */
 386     ele = string_copyn(ele, len);
 387
 388   if (Ustrlen(ele) == len)      /* ignore any with embedded nul */
 389     list = string_append_listele(list, osep,
 390           match == -1 ? string_sprintf("%s=%s", tag, ele) : ele);
 391   }
 392
 393 sk_GENERAL_NAME_free(san);
 394 return list;
 395 }
 396
 397 uschar *
 398 tls_cert_ocsp_uri(void * cert, uschar * mod)
 399 {
 400 STACK_OF(ACCESS_DESCRIPTION) * ads = (STACK_OF(ACCESS_DESCRIPTION) *)
 401   X509_get_ext_d2i((X509 *)cert, NID_info_access, NULL, NULL);
 402 int adsnum = sk_ACCESS_DESCRIPTION_num(ads);
 403 int i;
 404 uschar sep = '\n';
 405 uschar * list = NULL;
 406
 407 if (mod)
 408   if (*mod == '>' && *++mod) sep = *mod++;
 409
 410 for (i = 0; i < adsnum; i++)
 411   {
 412   ACCESS_DESCRIPTION * ad = sk_ACCESS_DESCRIPTION_value(ads, i);
 413
 414   if (ad && OBJ_obj2nid(ad->method) == NID_ad_OCSP)
 415     {
 416     uschar * ele = ASN1_STRING_data(ad->location->d.ia5);
 417     int len =  ASN1_STRING_length(ad->location->d.ia5);
 418     list = string_append_listele_n(list, sep, ele, len);
 419     }
 420   }
 421 sk_ACCESS_DESCRIPTION_free(ads);
 422 return list;
 423 }
 424
 425 uschar *
 426 tls_cert_crl_uri(void * cert, uschar * mod)
 427 {
 428 STACK_OF(DIST_POINT) * dps = (STACK_OF(DIST_POINT) *)
 429   X509_get_ext_d2i((X509 *)cert,  NID_crl_distribution_points,
 430     NULL, NULL);
 431 DIST_POINT * dp;
 432 int dpsnum = sk_DIST_POINT_num(dps);
 433 int i;
 434 uschar sep = '\n';
 435 uschar * list = NULL;
 436
 437 if (mod)
 438   if (*mod == '>' && *++mod) sep = *mod++;
 439
 440 if (dps) for (i = 0; i < dpsnum; i++)
 441   if ((dp = sk_DIST_POINT_value(dps, i)))
 442     {
 443     STACK_OF(GENERAL_NAME) * names = dp->distpoint->name.fullname;
 444     GENERAL_NAME * np;
 445     int nnum = sk_GENERAL_NAME_num(names);
 446     int j;
 447
 448     for (j = 0; j < nnum; j++)
 449       if (  (np = sk_GENERAL_NAME_value(names, j))
 450          && np->type == GEN_URI
 451          )
 452         {
 453         uschar * ele = ASN1_STRING_data(np->d.uniformResourceIdentifier);
 454         int len =  ASN1_STRING_length(np->d.uniformResourceIdentifier);
 455         list = string_append_listele_n(list, sep, ele, len);
 456         }
 457     }
 458 sk_DIST_POINT_free(dps);
 459 return list;
 460 }
 461
 462
 463
 464 /*****************************************************
 465 *  Certificate operator routines
 466 *****************************************************/
 467 static uschar *
 468 fingerprint(X509 * cert, const EVP_MD * fdig)
 469 {
 470 int j;
 471 unsigned int n;
 472 uschar md[EVP_MAX_MD_SIZE];
 473 uschar * cp;
 474
 475 if (!X509_digest(cert,fdig,md,&n))
 476   {
 477   expand_string_message = US"tls_cert_fprt: out of mem\n";
 478   return NULL;
 479   }
 480 cp = store_get(n*2+1);
 481 for (j = 0; j < (int)n; j++) sprintf(CS cp+2*j, "%02X", md[j]);
 482 return(cp);
 483 }
 484
 485 uschar *
 486 tls_cert_fprt_md5(void * cert)
 487 {
 488 return fingerprint((X509 *)cert, EVP_md5());
 489 }
 490
 491 uschar *
 492 tls_cert_fprt_sha1(void * cert)
 493 {
 494 return fingerprint((X509 *)cert, EVP_sha1());
 495 }
 496
 497 uschar *
 498 tls_cert_fprt_sha256(void * cert)
 499 {
 500 return fingerprint((X509 *)cert, EVP_sha256());
 501 }
 502
 503
 504 /* vi: aw ai sw=2
 505 */
 506 /* End of tlscert-openssl.c */