webcit/crypto.c

   1 /*
   2  * $Id$
   3  */
   4
   5 #include "sysdep.h"
   6 #ifdef HAVE_OPENSSL
   7
   8 #include "webcit.h"
   9 #include "webserver.h"
  10
  11 /* where to find the keys */
  12 #define CTDL_CRYPTO_DIR         ctdl_key_dir
  13 #define CTDL_KEY_PATH           file_crpt_file_key
  14 #define CTDL_CSR_PATH           file_crpt_file_csr
  15 #define CTDL_CER_PATH           file_crpt_file_cer
  16 #define SIGN_DAYS               3650                    /* how long our certificate should live */
  17
  18 SSL_CTX *ssl_ctx;               /* SSL context */
  19 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  20 char *ssl_cipher_list = DEFAULT_SSL_CIPHER_LIST;
  21
  22 pthread_key_t ThreadSSL;        /* Per-thread SSL context */
  23
  24 static unsigned long id_callback(void)
  25 {
  26         return (unsigned long) pthread_self();
  27 }
  28
  29 void shutdown_ssl(void)
  30 {
  31         ERR_free_strings();
  32
  33         /* Openssl requires these while shutdown.
  34          * Didn't find a way to get out of this clean.
  35          * int i, n = CRYPTO_num_locks();
  36          * for (i = 0; i < n; i++)
  37          *      free(SSLCritters[i]);
  38          * free(SSLCritters);
  39          */
  40 }
  41
  42 /*
  43  * initialize ssl engine, load certs and initialize openssl internals
  44  */
  45 void init_ssl(void)
  46 {
  47         SSL_METHOD *ssl_method;
  48         RSA *rsa=NULL;
  49         X509_REQ *req = NULL;
  50         X509 *cer = NULL;
  51         EVP_PKEY *pk = NULL;
  52         EVP_PKEY *req_pkey = NULL;
  53         X509_NAME *name = NULL;
  54         FILE *fp;
  55         char buf[SIZ];
  56         int rv = 0;
  57
  58         if (!access("/var/run/egd-pool", F_OK)) {
  59                 RAND_egd("/var/run/egd-pool");
  60         }
  61
  62         if (!RAND_status()) {
  63                 lprintf(3, "PRNG not adequately seeded, won't do SSL/TLS\n");
  64                 return;
  65         }
  66         SSLCritters = malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  67         if (!SSLCritters) {
  68                 lprintf(1, "citserver: can't allocate memory!!\n");
  69                 /* Nothing's been initialized, just die */
  70                 ShutDownWebcit();
  71                 exit(WC_EXIT_SSL);
  72         } else {
  73                 int a;
  74
  75                 for (a = 0; a < CRYPTO_num_locks(); a++) {
  76                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
  77                         if (!SSLCritters[a]) {
  78                                 lprintf(1,
  79                                         "citserver: can't allocate memory!!\n");
  80                                 /** Nothing's been initialized, just die */
  81                                 ShutDownWebcit();
  82                                 exit(WC_EXIT_SSL);
  83                         }
  84                         pthread_mutex_init(SSLCritters[a], NULL);
  85                 }
  86         }
  87
  88         /*
  89          * Initialize SSL transport layer
  90          */
  91         SSL_library_init();
  92         SSL_load_error_strings();
  93         ssl_method = SSLv23_server_method();
  94         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
  95                 lprintf(3, "SSL_CTX_new failed: %s\n", ERR_reason_error_string(ERR_get_error()));
  96                 return;
  97         }
  98
  99         lprintf(9, "Requesting cipher list: %s\n", ssl_cipher_list);
 100         if (!(SSL_CTX_set_cipher_list(ssl_ctx, ssl_cipher_list))) {
 101                 lprintf(3, "SSL_CTX_set_cipher_list failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 102                 return;
 103         }
 104
 105         CRYPTO_set_locking_callback(ssl_lock);
 106         CRYPTO_set_id_callback(id_callback);
 107
 108         /*
 109          * Get our certificates in order. (FIXME: dirify. this is a setup job.)
 110          * First, create the key/cert directory if it's not there already...
 111          */
 112         mkdir(CTDL_CRYPTO_DIR, 0700);
 113
 114         /*
 115          * Before attempting to generate keys/certificates, first try
 116          * link to them from the Citadel server if it's on the same host.
 117          * We ignore any error return because it either meant that there
 118          * was nothing in Citadel to link from (in which case we just
 119          * generate new files) or the target files already exist (which
 120          * is not fatal either).
 121          */
 122         if (!strcasecmp(ctdlhost, "uds")) {
 123                 sprintf(buf, "%s/keys/citadel.key", ctdlport);
 124                 rv = symlink(buf, CTDL_KEY_PATH);
 125                 if (!rv) lprintf(1, "%s\n", strerror(errno));
 126                 sprintf(buf, "%s/keys/citadel.csr", ctdlport);
 127                 rv = symlink(buf, CTDL_CSR_PATH);
 128                 if (!rv) lprintf(1, "%s\n", strerror(errno));
 129                 sprintf(buf, "%s/keys/citadel.cer", ctdlport);
 130                 rv = symlink(buf, CTDL_CER_PATH);
 131                 if (!rv) lprintf(1, "%s\n", strerror(errno));
 132         }
 133
 134         /*
 135          * If we still don't have a private key, generate one.
 136          */
 137         if (access(CTDL_KEY_PATH, R_OK) != 0) {
 138                 lprintf(5, "Generating RSA key pair.\n");
 139                 rsa = RSA_generate_key(1024,    /* modulus size */
 140                                         65537,  /* exponent */
 141                                         NULL,   /* no callback */
 142                                         NULL    /* no callback */
 143                 );
 144                 if (rsa == NULL) {
 145                         lprintf(3, "Key generation failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 146                 }
 147                 if (rsa != NULL) {
 148                         fp = fopen(CTDL_KEY_PATH, "w");
 149                         if (fp != NULL) {
 150                                 chmod(CTDL_KEY_PATH, 0600);
 151                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 152                                                         rsa,    /* the key */
 153                                                         NULL,   /* no enc */
 154                                                         NULL,   /* no passphr */
 155                                                         0,      /* no passphr */
 156                                                         NULL,   /* no callbk */
 157                                                         NULL    /* no callbk */
 158                                 ) != 1) {
 159                                         lprintf(3, "Cannot write key: %s\n",
 160                                                 ERR_reason_error_string(ERR_get_error()));
 161                                         unlink(CTDL_KEY_PATH);
 162                                 }
 163                                 fclose(fp);
 164                         }
 165                         else {
 166                                 lprintf(3, "Cannot write key: %s\n", CTDL_KEY_PATH);
 167                                 ShutDownWebcit();
 168                                 exit(0);
 169                         }
 170                         RSA_free(rsa);
 171                 }
 172         }
 173
 174         /*
 175          * If there is no certificate file on disk, we will be generating a self-signed certificate
 176          * in the next step.  Therefore, if we have neither a CSR nor a certificate, generate
 177          * the CSR in this step so that the next step may commence.
 178          */
 179         if ( (access(CTDL_CER_PATH, R_OK) != 0) && (access(CTDL_CSR_PATH, R_OK) != 0) ) {
 180                 lprintf(5, "Generating a certificate signing request.\n");
 181
 182                 /*
 183                  * Read our key from the file.  No, we don't just keep this
 184                  * in memory from the above key-generation function, because
 185                  * there is the possibility that the key was already on disk
 186                  * and we didn't just generate it now.
 187                  */
 188                 fp = fopen(CTDL_KEY_PATH, "r");
 189                 if (fp) {
 190                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 191                         fclose(fp);
 192                 }
 193
 194                 if (rsa) {
 195
 196                         /** Create a public key from the private key */
 197                         if (pk=EVP_PKEY_new(), pk != NULL) {
 198                                 EVP_PKEY_assign_RSA(pk, rsa);
 199                                 if (req = X509_REQ_new(), req != NULL) {
 200                                         const char *env;
 201                                         /* Set the public key */
 202                                         X509_REQ_set_pubkey(req, pk);
 203                                         X509_REQ_set_version(req, 0L);
 204
 205                                         name = X509_REQ_get_subject_name(req);
 206
 207                                         /* Tell it who we are */
 208
 209                                         /*
 210                                          * We used to add these fields to the subject, but
 211                                          * now we don't.  Someone doing this for real isn't
 212                                          * going to use the webcit-generated CSR anyway.
 213                                          *
 214                                         X509_NAME_add_entry_by_txt(name, "C",
 215                                                 MBSTRING_ASC, "US", -1, -1, 0);
 216                                         *
 217                                         X509_NAME_add_entry_by_txt(name, "ST",
 218                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 219                                         *
 220                                         X509_NAME_add_entry_by_txt(name, "L",
 221                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 222                                         */
 223
 224                                         env = getenv("O");
 225                                         if (env == NULL)
 226                                                 env = "Organization name",
 227
 228                                         X509_NAME_add_entry_by_txt(
 229                                                 name, "O",
 230                                                 MBSTRING_ASC,
 231                                                 (unsigned char*)env,
 232                                                 -1, -1, 0
 233                                         );
 234
 235                                         env = getenv("OU");
 236                                         if (env == NULL)
 237                                                 env = "Citadel server";
 238
 239                                         X509_NAME_add_entry_by_txt(
 240                                                 name, "OU",
 241                                                 MBSTRING_ASC,
 242                                                 (unsigned char*)env,
 243                                                 -1, -1, 0
 244                                         );
 245
 246                                         env = getenv("CN");
 247                                         if (env == NULL)
 248                                                 env = "*";
 249
 250                                         X509_NAME_add_entry_by_txt(
 251                                                 name, "CN",
 252                                                 MBSTRING_ASC,
 253                                                 (unsigned char*)env,
 254                                                 -1, -1, 0
 255                                         );
 256
 257                                         X509_REQ_set_subject_name(req, name);
 258
 259                                         /* Sign the CSR */
 260                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 261                                                 lprintf(3, "X509_REQ_sign(): error\n");
 262                                         }
 263                                         else {
 264                                                 /* Write it to disk. */
 265                                                 fp = fopen(CTDL_CSR_PATH, "w");
 266                                                 if (fp != NULL) {
 267                                                         chmod(CTDL_CSR_PATH, 0600);
 268                                                         PEM_write_X509_REQ(fp, req);
 269                                                         fclose(fp);
 270                                                 }
 271                                                 else {
 272                                                         lprintf(3, "Cannot write key: %s\n", CTDL_CSR_PATH);
 273                                                         ShutDownWebcit();
 274                                                         exit(0);
 275                                                 }
 276                                         }
 277
 278                                         X509_REQ_free(req);
 279                                 }
 280                         }
 281
 282                         RSA_free(rsa);
 283                 }
 284
 285                 else {
 286                         lprintf(3, "Unable to read private key.\n");
 287                 }
 288         }
 289
 290
 291
 292         /*
 293          * Generate a self-signed certificate if we don't have one.
 294          */
 295         if (access(CTDL_CER_PATH, R_OK) != 0) {
 296                 lprintf(5, "Generating a self-signed certificate.\n");
 297
 298                 /* Same deal as before: always read the key from disk because
 299                  * it may or may not have just been generated.
 300                  */
 301                 fp = fopen(CTDL_KEY_PATH, "r");
 302                 if (fp) {
 303                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 304                         fclose(fp);
 305                 }
 306
 307                 /* This also holds true for the CSR. */
 308                 req = NULL;
 309                 cer = NULL;
 310                 pk = NULL;
 311                 if (rsa) {
 312                         if (pk=EVP_PKEY_new(), pk != NULL) {
 313                                 EVP_PKEY_assign_RSA(pk, rsa);
 314                         }
 315
 316                         fp = fopen(CTDL_CSR_PATH, "r");
 317                         if (fp) {
 318                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 319                                 fclose(fp);
 320                         }
 321
 322                         if (req) {
 323                                 if (cer = X509_new(), cer != NULL) {
 324
 325                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 326                                         X509_set_issuer_name(cer, req->req_info->subject);
 327                                         X509_set_subject_name(cer, req->req_info->subject);
 328                                         X509_gmtime_adj(X509_get_notBefore(cer), 0);
 329                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 330
 331                                         req_pkey = X509_REQ_get_pubkey(req);
 332                                         X509_set_pubkey(cer, req_pkey);
 333                                         EVP_PKEY_free(req_pkey);
 334
 335                                         /* Sign the cert */
 336                                         if (!X509_sign(cer, pk, EVP_md5())) {
 337                                                 lprintf(3, "X509_sign(): error\n");
 338                                         }
 339                                         else {
 340                                                 /* Write it to disk. */
 341                                                 fp = fopen(CTDL_CER_PATH, "w");
 342                                                 if (fp != NULL) {
 343                                                         chmod(CTDL_CER_PATH, 0600);
 344                                                         PEM_write_X509(fp, cer);
 345                                                         fclose(fp);
 346                                                 }
 347                                                 else {
 348                                                         lprintf(3, "Cannot write key: %s\n", CTDL_CER_PATH);
 349                                                         ShutDownWebcit();
 350                                                         exit(0);
 351                                                 }
 352                                         }
 353                                         X509_free(cer);
 354                                 }
 355                         }
 356
 357                         RSA_free(rsa);
 358                 }
 359         }
 360
 361         /*
 362          * Now try to bind to the key and certificate.
 363          * Note that we use SSL_CTX_use_certificate_chain_file() which allows
 364          * the certificate file to contain intermediate certificates.
 365          */
 366         SSL_CTX_use_certificate_chain_file(ssl_ctx, CTDL_CER_PATH);
 367         SSL_CTX_use_PrivateKey_file(ssl_ctx, CTDL_KEY_PATH, SSL_FILETYPE_PEM);
 368         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 369                 lprintf(3, "Cannot install certificate: %s\n",
 370                                 ERR_reason_error_string(ERR_get_error()));
 371         }
 372
 373 }
 374
 375
 376 /*
 377  * starts SSL/TLS encryption for the current session.
 378  */
 379 int starttls(int sock) {
 380         int retval, bits, alg_bits, r;
 381         SSL *newssl;
 382
 383         pthread_setspecific(ThreadSSL, NULL);
 384
 385         if (!ssl_ctx) {
 386                 return(1);
 387         }
 388         if (!(newssl = SSL_new(ssl_ctx))) {
 389                 lprintf(3, "SSL_new failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 390                 return(2);
 391         }
 392         if (!(SSL_set_fd(newssl, sock))) {
 393                 lprintf(3, "SSL_set_fd failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 394                 SSL_free(newssl);
 395                 return(3);
 396         }
 397         retval = SSL_accept(newssl);
 398         if (retval < 1) {
 399                 /*
 400                  * Can't notify the client of an error here; they will
 401                  * discover the problem at the SSL layer and should
 402                  * revert to unencrypted communications.
 403                  */
 404                 long errval;
 405                 const char *ssl_error_reason = NULL;
 406
 407                 errval = SSL_get_error(newssl, retval);
 408                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 409                 if (ssl_error_reason == NULL) {
 410                         lprintf(3, "SSL_accept failed: errval=%i, retval=%i %s\n", errval, retval, strerror(errval));
 411                 }
 412                 else {
 413                         lprintf(3, "SSL_accept failed: %s\n", ssl_error_reason);
 414                 }
 415                 sleeeeeeeeeep(1);
 416                 retval = SSL_accept(newssl);
 417         }
 418         if (retval < 1) {
 419                 long errval;
 420                 const char *ssl_error_reason = NULL;
 421
 422                 errval = SSL_get_error(newssl, retval);
 423                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 424                 if (ssl_error_reason == NULL) {
 425                         lprintf(3, "SSL_accept failed: errval=%i, retval=%i (%s)\n", errval, retval, strerror(errval));
 426                 }
 427                 else {
 428                         lprintf(3, "SSL_accept failed: %s\n", ssl_error_reason);
 429                 }
 430                 SSL_free(newssl);
 431                 newssl = NULL;
 432                 return(4);
 433         }
 434         else {
 435                 lprintf(15, "SSL_accept success\n");
 436         }
 437         r = BIO_set_close(newssl->rbio, BIO_NOCLOSE);
 438         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl), &alg_bits);
 439         lprintf(15, "SSL/TLS using %s on %s (%d of %d bits)\n",
 440                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 441                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 442                 bits, alg_bits);
 443
 444         pthread_setspecific(ThreadSSL, newssl);
 445         lprintf(15, "SSL started\n");
 446         return(0);
 447 }
 448
 449
 450
 451 /*
 452  * shuts down the TLS connection
 453  *
 454  * WARNING:  This may make your session vulnerable to a known plaintext
 455  * attack in the current implmentation.
 456  */
 457 void endtls(void)
 458 {
 459         SSL_CTX *ctx = NULL;
 460
 461         if (THREADSSL == NULL) return;
 462
 463         lprintf(15, "Ending SSL/TLS\n");
 464         SSL_shutdown(THREADSSL);
 465         ctx = SSL_get_SSL_CTX(THREADSSL);
 466
 467         /* I don't think this is needed, and it crashes the server anyway
 468          *
 469          *      if (ctx != NULL) {
 470          *              lprintf(9, "Freeing CTX at %x\n", (int)ctx );
 471          *              SSL_CTX_free(ctx);
 472          *      }
 473          */
 474
 475         SSL_free(THREADSSL);
 476         pthread_setspecific(ThreadSSL, NULL);
 477 }
 478
 479
 480 /*
 481  * callback for OpenSSL mutex locks
 482  */
 483 void ssl_lock(int mode, int n, const char *file, int line)
 484 {
 485         if (mode & CRYPTO_LOCK) {
 486                 pthread_mutex_lock(SSLCritters[n]);
 487         }
 488         else {
 489                 pthread_mutex_unlock(SSLCritters[n]);
 490         }
 491 }
 492
 493 /*
 494  * Send binary data to the client encrypted.
 495  */
 496 void client_write_ssl(const StrBuf *Buf)
 497 {
 498         const char *buf;
 499         int retval;
 500         int nremain;
 501         long nbytes;
 502         char junk[1];
 503
 504         if (THREADSSL == NULL) return;
 505
 506         nbytes = nremain = StrLength(Buf);
 507         buf = ChrPtr(Buf);
 508
 509         while (nremain > 0) {
 510                 if (SSL_want_write(THREADSSL)) {
 511                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 512                                 lprintf(9, "SSL_read in client_write: %s\n",
 513                                                 ERR_reason_error_string(ERR_get_error()));
 514                         }
 515                 }
 516                 retval = SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 517                 if (retval < 1) {
 518                         long errval;
 519
 520                         errval = SSL_get_error(THREADSSL, retval);
 521                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 522                                 sleeeeeeeeeep(1);
 523                                 continue;
 524                         }
 525                         lprintf(9, "SSL_write got error %ld, ret %d\n", errval, retval);
 526                         if (retval == -1) {
 527                                 lprintf(9, "errno is %d\n", errno);
 528                         }
 529                         endtls();
 530                         return;
 531                 }
 532                 nremain -= retval;
 533         }
 534 }
 535
 536
 537 /*
 538  * read data from the encrypted layer.
 539  */
 540 int client_read_sslbuffer(StrBuf *buf, int timeout)
 541 {
 542         char sbuf[16384]; /* OpenSSL communicates in 16k blocks, so let's speak its native tongue. */
 543         int rlen;
 544         char junk[1];
 545         SSL *pssl = THREADSSL;
 546
 547         if (pssl == NULL) return(-1);
 548
 549         while (1) {
 550                 if (SSL_want_read(pssl)) {
 551                         if ((SSL_write(pssl, junk, 0)) < 1) {
 552                                 lprintf(9, "SSL_write in client_read\n");
 553                         }
 554                 }
 555                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 556                 if (rlen < 1) {
 557                         long errval;
 558
 559                         errval = SSL_get_error(pssl, rlen);
 560                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 561                                 sleeeeeeeeeep(1);
 562                                 continue;
 563                         }
 564                         lprintf(9, "SSL_read got error %ld\n", errval);
 565                         endtls();
 566                         return (-1);
 567                 }
 568                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 569                 return rlen;
 570         }
 571         return (0);
 572 }
 573
 574 #endif                          /* HAVE_OPENSSL */