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