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(name, "O",
 206                                                 MBSTRING_ASC, "Organization name", -1, -1, 0);
 207
 208                                         X509_NAME_add_entry_by_txt(name, "OU",
 209                                                 MBSTRING_ASC, "Citadel server", -1, -1, 0);
 210
 211                                         X509_NAME_add_entry_by_txt(name, "CN",
 212                                                 MBSTRING_ASC, "*", -1, -1, 0);
 213
 214                                         X509_REQ_set_subject_name(req, name);
 215
 216                                         /** Sign the CSR */
 217                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 218                                                 lprintf(3, "X509_REQ_sign(): error\n");
 219                                         }
 220                                         else {
 221                                                 /** Write it to disk. */
 222                                                 fp = fopen(CTDL_CSR_PATH, "w");
 223                                                 if (fp != NULL) {
 224                                                         chmod(CTDL_CSR_PATH, 0600);
 225                                                         PEM_write_X509_REQ(fp, req);
 226                                                         fclose(fp);
 227                                                 }
 228                                                 else {
 229                                                         lprintf(3, "Cannot write key: %s\n", CTDL_CSR_PATH);
 230                                                         exit(0);
 231                                                 }
 232                                         }
 233
 234                                         X509_REQ_free(req);
 235                                 }
 236                         }
 237
 238                         RSA_free(rsa);
 239                 }
 240
 241                 else {
 242                         lprintf(3, "Unable to read private key.\n");
 243                 }
 244         }
 245
 246
 247
 248         /**
 249          * Generate a self-signed certificate if we don't have one.
 250          */
 251         if (access(CTDL_CER_PATH, R_OK) != 0) {
 252                 lprintf(5, "Generating a self-signed certificate.\n");
 253
 254                 /** Same deal as before: always read the key from disk because
 255                  * it may or may not have just been generated.
 256                  */
 257                 fp = fopen(CTDL_KEY_PATH, "r");
 258                 if (fp) {
 259                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 260                         fclose(fp);
 261                 }
 262
 263                 /** This also holds true for the CSR. */
 264                 req = NULL;
 265                 cer = NULL;
 266                 pk = NULL;
 267                 if (rsa) {
 268                         if (pk=EVP_PKEY_new(), pk != NULL) {
 269                                 EVP_PKEY_assign_RSA(pk, rsa);
 270                         }
 271
 272                         fp = fopen(CTDL_CSR_PATH, "r");
 273                         if (fp) {
 274                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 275                                 fclose(fp);
 276                         }
 277
 278                         if (req) {
 279                                 if (cer = X509_new(), cer != NULL) {
 280
 281                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 282                                         X509_set_issuer_name(cer, req->req_info->subject);
 283                                         X509_set_subject_name(cer, req->req_info->subject);
 284                                         X509_gmtime_adj(X509_get_notBefore(cer), 0);
 285                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 286
 287                                         req_pkey = X509_REQ_get_pubkey(req);
 288                                         X509_set_pubkey(cer, req_pkey);
 289                                         EVP_PKEY_free(req_pkey);
 290
 291                                         /** Sign the cert */
 292                                         if (!X509_sign(cer, pk, EVP_md5())) {
 293                                                 lprintf(3, "X509_sign(): error\n");
 294                                         }
 295                                         else {
 296                                                 /** Write it to disk. */
 297                                                 fp = fopen(CTDL_CER_PATH, "w");
 298                                                 if (fp != NULL) {
 299                                                         chmod(CTDL_CER_PATH, 0600);
 300                                                         PEM_write_X509(fp, cer);
 301                                                         fclose(fp);
 302                                                 }
 303                                                 else {
 304                                                         lprintf(3, "Cannot write key: %s\n", CTDL_CER_PATH);
 305                                                         exit(0);
 306                                                 }
 307                                         }
 308                                         X509_free(cer);
 309                                 }
 310                         }
 311
 312                         RSA_free(rsa);
 313                 }
 314         }
 315
 316         /**
 317          * Now try to bind to the key and certificate.
 318          * Note that we use SSL_CTX_use_certificate_chain_file() which allows
 319          * the certificate file to contain intermediate certificates.
 320          */
 321         SSL_CTX_use_certificate_chain_file(ssl_ctx, CTDL_CER_PATH);
 322         SSL_CTX_use_PrivateKey_file(ssl_ctx, CTDL_KEY_PATH, SSL_FILETYPE_PEM);
 323         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 324                 lprintf(3, "Cannot install certificate: %s\n",
 325                                 ERR_reason_error_string(ERR_get_error()));
 326         }
 327
 328 }
 329
 330
 331 /**
 332  * \brief starts SSL/TLS encryption for the current session.
 333  * \param sock the socket connection
 334  * \return Zero if the SSL/TLS handshake succeeded, non-zero otherwise.
 335  */
 336 int starttls(int sock) {
 337         int retval, bits, alg_bits;
 338         SSL *newssl;
 339
 340         pthread_setspecific(ThreadSSL, NULL);
 341
 342         if (!ssl_ctx) {
 343                 return(1);
 344         }
 345         if (!(newssl = SSL_new(ssl_ctx))) {
 346                 lprintf(3, "SSL_new failed: %s\n",
 347                                 ERR_reason_error_string(ERR_get_error()));
 348                 return(2);
 349         }
 350         if (!(SSL_set_fd(newssl, sock))) {
 351                 lprintf(3, "SSL_set_fd failed: %s\n",
 352                         ERR_reason_error_string(ERR_get_error()));
 353                 SSL_free(newssl);
 354                 return(3);
 355         }
 356         retval = SSL_accept(newssl);
 357         if (retval < 1) {
 358                 /**
 359                  * Can't notify the client of an error here; they will
 360                  * discover the problem at the SSL layer and should
 361                  * revert to unencrypted communications.
 362                  */
 363                 long errval;
 364
 365                 errval = SSL_get_error(newssl, retval);
 366                 lprintf(3, "SSL_accept failed: %s\n",
 367                         ERR_reason_error_string(ERR_get_error()));
 368                 SSL_free(newssl);
 369                 newssl = NULL;
 370                 return(4);
 371         }
 372         BIO_set_close(newssl->rbio, BIO_NOCLOSE);
 373         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl), &alg_bits);
 374         lprintf(5, "SSL/TLS using %s on %s (%d of %d bits)\n",
 375                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 376                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 377                 bits, alg_bits);
 378
 379         pthread_setspecific(ThreadSSL, newssl);
 380         return(0);
 381 }
 382
 383
 384
 385 /**
 386  * \brief shuts down the TLS connection
 387  *
 388  * WARNING:  This may make your session vulnerable to a known plaintext
 389  * attack in the current implmentation.
 390  */
 391 void endtls(void)
 392 {
 393         SSL_CTX *ctx = NULL;
 394
 395         if (THREADSSL == NULL) return;
 396
 397         lprintf(5, "Ending SSL/TLS\n");
 398         SSL_shutdown(THREADSSL);
 399         ctx = SSL_get_SSL_CTX(THREADSSL);
 400
 401         /** I don't think this is needed, and it crashes the server anyway
 402          *
 403          *      if (ctx != NULL) {
 404          *              lprintf(9, "Freeing CTX at %x\n", (int)ctx );
 405          *              SSL_CTX_free(ctx);
 406          *      }
 407          */
 408
 409         SSL_free(THREADSSL);
 410         pthread_setspecific(ThreadSSL, NULL);
 411 }
 412
 413
 414 /**
 415  * \brief callback for OpenSSL mutex locks
 416  * \param mode which mode??????
 417  * \param n  how many???
 418  * \param file which filename ???
 419  * \param line what line????
 420  */
 421 void ssl_lock(int mode, int n, const char *file, int line)
 422 {
 423         if (mode & CRYPTO_LOCK)
 424                 pthread_mutex_lock(SSLCritters[n]);
 425         else
 426                 pthread_mutex_unlock(SSLCritters[n]);
 427 }
 428
 429 /**
 430  * \brief Send binary data to the client encrypted.
 431  * \param buf chars to send to the client
 432  * \param nbytes how many chars
 433  */
 434 void client_write_ssl(char *buf, int nbytes)
 435 {
 436         int retval;
 437         int nremain;
 438         char junk[1];
 439
 440         if (THREADSSL == NULL) return;
 441
 442         nremain = nbytes;
 443
 444         while (nremain > 0) {
 445                 if (SSL_want_write(THREADSSL)) {
 446                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 447                                 lprintf(9, "SSL_read in client_write: %s\n",
 448                                                 ERR_reason_error_string(ERR_get_error()));
 449                         }
 450                 }
 451                 retval = SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 452                 if (retval < 1) {
 453                         long errval;
 454
 455                         errval = SSL_get_error(THREADSSL, retval);
 456                         if (errval == SSL_ERROR_WANT_READ ||
 457                             errval == SSL_ERROR_WANT_WRITE) {
 458                                 sleep(1);
 459                                 continue;
 460                         }
 461                         lprintf(9, "SSL_write got error %ld, ret %d\n", errval, retval);
 462                         if (retval == -1) {
 463                                 lprintf(9, "errno is %d\n", errno);
 464                         }
 465                         endtls();
 466                         return;
 467                 }
 468                 nremain -= retval;
 469         }
 470 }
 471
 472
 473 /**
 474  * \brief read data from the encrypted layer.
 475  * \param buf charbuffer to read to
 476  * \param bytes how many
 477  * \param timeout how long should we wait?
 478  * \returns what???
 479  */
 480 int client_read_ssl(char *buf, int bytes, int timeout)
 481 {
 482 #if 0
 483         fd_set rfds;
 484         struct timeval tv;
 485         int retval;
 486         int s;
 487 #endif
 488         int len, rlen;
 489         char junk[1];
 490
 491         if (THREADSSL == NULL) return(0);
 492
 493         len = 0;
 494         while (len < bytes) {
 495 #if 0
 496                 /**
 497                  * This code is disabled because we don't need it when
 498                  * using blocking reads (which we are). -IO
 499                  */
 500                 FD_ZERO(&rfds);
 501                 s = BIO_get_fd(THREADSSL->rbio, NULL);
 502                 FD_SET(s, &rfds);
 503                 tv.tv_sec = timeout;
 504                 tv.tv_usec = 0;
 505
 506                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 507
 508                 if (FD_ISSET(s, &rfds) == 0) {
 509                         return (0);
 510                 }
 511
 512 #endif
 513                 if (SSL_want_read(THREADSSL)) {
 514                         if ((SSL_write(THREADSSL, junk, 0)) < 1) {
 515                                 lprintf(9, "SSL_write in client_read: %s\n", ERR_reason_error_string(ERR_get_error()));
 516                         }
 517                 }
 518                 rlen = SSL_read(THREADSSL, &buf[len], bytes - len);
 519                 if (rlen < 1) {
 520                         long errval;
 521
 522                         errval = SSL_get_error(THREADSSL, rlen);
 523                         if (errval == SSL_ERROR_WANT_READ ||
 524                             errval == SSL_ERROR_WANT_WRITE) {
 525                                 sleep(1);
 526                                 continue;
 527                         }
 528                         lprintf(9, "SSL_read got error %ld\n", errval);
 529                         endtls();
 530                         return (0);
 531                 }
 532                 len += rlen;
 533         }
 534         return (1);
 535 }
 536
 537
 538 #endif                          /* HAVE_OPENSSL */
 539 /*@}*/