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