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