webcit/crypto.c

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