src/src/tlscert-openssl.c

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