webcit/crypto.c

   1 /*
   2  * Copyright (c) 1996-2012 by the citadel.org team
   3  *
   4  * This program is open source software.  You can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License, version 3.
   6  *
   7  *
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  *
  15  *
  16  *
  17  */
  18
  19 #include "sysdep.h"
  20 #ifdef HAVE_OPENSSL
  21
  22 #include "webcit.h"
  23 #include "webserver.h"
  24
  25 /* where to find the keys */
  26 #define CTDL_CRYPTO_DIR         ctdl_key_dir
  27 #define CTDL_KEY_PATH           file_crpt_file_key
  28 #define CTDL_CSR_PATH           file_crpt_file_csr
  29 #define CTDL_CER_PATH           file_crpt_file_cer
  30 #define SIGN_DAYS               3650                    /* how long our certificate should live */
  31
  32 SSL_CTX *ssl_ctx;               /* SSL context */
  33 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  34 char *ssl_cipher_list = DEFAULT_SSL_CIPHER_LIST;
  35
  36 pthread_key_t ThreadSSL;        /* Per-thread SSL context */
  37
  38 static unsigned long id_callback(void)
  39 {
  40         return (unsigned long) pthread_self();
  41 }
  42
  43 void shutdown_ssl(void)
  44 {
  45         ERR_free_strings();
  46
  47         /* Openssl requires these while shutdown.
  48          * Didn't find a way to get out of this clean.
  49          * int i, n = CRYPTO_num_locks();
  50          * for (i = 0; i < n; i++)
  51          *      free(SSLCritters[i]);
  52          * free(SSLCritters);
  53          */
  54 }
  55
  56 /*
  57  * initialize ssl engine, load certs and initialize openssl internals
  58  */
  59 void init_ssl(void)
  60 {
  61         const SSL_METHOD *ssl_method;
  62         RSA *rsa=NULL;
  63         X509_REQ *req = NULL;
  64         X509 *cer = NULL;
  65         EVP_PKEY *pk = NULL;
  66         EVP_PKEY *req_pkey = NULL;
  67         X509_NAME *name = NULL;
  68         FILE *fp;
  69         char buf[SIZ];
  70         int rv = 0;
  71
  72         if (!access("/var/run/egd-pool", F_OK)) {
  73                 RAND_egd("/var/run/egd-pool");
  74         }
  75
  76         if (!RAND_status()) {
  77                 syslog(3, "PRNG not adequately seeded, won't do SSL/TLS\n");
  78                 return;
  79         }
  80         SSLCritters = malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  81         if (!SSLCritters) {
  82                 syslog(1, "citserver: can't allocate memory!!\n");
  83                 /* Nothing's been initialized, just die */
  84                 ShutDownWebcit();
  85                 exit(WC_EXIT_SSL);
  86         } else {
  87                 int a;
  88
  89                 for (a = 0; a < CRYPTO_num_locks(); a++) {
  90                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
  91                         if (!SSLCritters[a]) {
  92                                 syslog(1,
  93                                         "citserver: can't allocate memory!!\n");
  94                                 /** Nothing's been initialized, just die */
  95                                 ShutDownWebcit();
  96                                 exit(WC_EXIT_SSL);
  97                         }
  98                         pthread_mutex_init(SSLCritters[a], NULL);
  99                 }
 100         }
 101
 102         /*
 103          * Initialize SSL transport layer
 104          */
 105         SSL_library_init();
 106         SSL_load_error_strings();
 107         ssl_method = SSLv23_server_method();
 108         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 109                 syslog(3, "SSL_CTX_new failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 110                 return;
 111         }
 112
 113         syslog(9, "Requesting cipher list: %s\n", ssl_cipher_list);
 114         if (!(SSL_CTX_set_cipher_list(ssl_ctx, ssl_cipher_list))) {
 115                 syslog(3, "SSL_CTX_set_cipher_list failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 116                 return;
 117         }
 118
 119         CRYPTO_set_locking_callback(ssl_lock);
 120         CRYPTO_set_id_callback(id_callback);
 121
 122         /*
 123          * Get our certificates in order. (FIXME: dirify. this is a setup job.)
 124          * First, create the key/cert directory if it's not there already...
 125          */
 126         mkdir(CTDL_CRYPTO_DIR, 0700);
 127
 128         /*
 129          * Before attempting to generate keys/certificates, first try
 130          * link to them from the Citadel server if it's on the same host.
 131          * We ignore any error return because it either meant that there
 132          * was nothing in Citadel to link from (in which case we just
 133          * generate new files) or the target files already exist (which
 134          * is not fatal either).
 135          */
 136         if (!strcasecmp(ctdlhost, "uds")) {
 137                 sprintf(buf, "%s/keys/citadel.key", ctdlport);
 138                 rv = symlink(buf, CTDL_KEY_PATH);
 139                 if (!rv) syslog(1, "%s\n", strerror(errno));
 140                 sprintf(buf, "%s/keys/citadel.csr", ctdlport);
 141                 rv = symlink(buf, CTDL_CSR_PATH);
 142                 if (!rv) syslog(1, "%s\n", strerror(errno));
 143                 sprintf(buf, "%s/keys/citadel.cer", ctdlport);
 144                 rv = symlink(buf, CTDL_CER_PATH);
 145                 if (!rv) syslog(1, "%s\n", strerror(errno));
 146         }
 147
 148         /*
 149          * If we still don't have a private key, generate one.
 150          */
 151         if (access(CTDL_KEY_PATH, R_OK) != 0) {
 152                 syslog(5, "Generating RSA key pair.\n");
 153                 rsa = RSA_generate_key(1024,    /* modulus size */
 154                                         65537,  /* exponent */
 155                                         NULL,   /* no callback */
 156                                         NULL    /* no callback */
 157                 );
 158                 if (rsa == NULL) {
 159                         syslog(3, "Key generation failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 160                 }
 161                 if (rsa != NULL) {
 162                         fp = fopen(CTDL_KEY_PATH, "w");
 163                         if (fp != NULL) {
 164                                 chmod(CTDL_KEY_PATH, 0600);
 165                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 166                                                         rsa,    /* the key */
 167                                                         NULL,   /* no enc */
 168                                                         NULL,   /* no passphr */
 169                                                         0,      /* no passphr */
 170                                                         NULL,   /* no callbk */
 171                                                         NULL    /* no callbk */
 172                                 ) != 1) {
 173                                         syslog(3, "Cannot write key: %s\n",
 174                                                 ERR_reason_error_string(ERR_get_error()));
 175                                         unlink(CTDL_KEY_PATH);
 176                                 }
 177                                 fclose(fp);
 178                         }
 179                         else {
 180                                 syslog(3, "Cannot write key: %s\n", CTDL_KEY_PATH);
 181                                 ShutDownWebcit();
 182                                 exit(0);
 183                         }
 184                         RSA_free(rsa);
 185                 }
 186         }
 187
 188         /*
 189          * If there is no certificate file on disk, we will be generating a self-signed certificate
 190          * in the next step.  Therefore, if we have neither a CSR nor a certificate, generate
 191          * the CSR in this step so that the next step may commence.
 192          */
 193         if ( (access(CTDL_CER_PATH, R_OK) != 0) && (access(CTDL_CSR_PATH, R_OK) != 0) ) {
 194                 syslog(5, "Generating a certificate signing request.\n");
 195
 196                 /*
 197                  * Read our key from the file.  No, we don't just keep this
 198                  * in memory from the above key-generation function, because
 199                  * there is the possibility that the key was already on disk
 200                  * and we didn't just generate it now.
 201                  */
 202                 fp = fopen(CTDL_KEY_PATH, "r");
 203                 if (fp) {
 204                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 205                         fclose(fp);
 206                 }
 207
 208                 if (rsa) {
 209
 210                         /** Create a public key from the private key */
 211                         if (pk=EVP_PKEY_new(), pk != NULL) {
 212                                 EVP_PKEY_assign_RSA(pk, rsa);
 213                                 if (req = X509_REQ_new(), req != NULL) {
 214                                         const char *env;
 215                                         /* Set the public key */
 216                                         X509_REQ_set_pubkey(req, pk);
 217                                         X509_REQ_set_version(req, 0L);
 218
 219                                         name = X509_REQ_get_subject_name(req);
 220
 221                                         /* Tell it who we are */
 222
 223                                         /*
 224                                          * We used to add these fields to the subject, but
 225                                          * now we don't.  Someone doing this for real isn't
 226                                          * going to use the webcit-generated CSR anyway.
 227                                          *
 228                                         X509_NAME_add_entry_by_txt(name, "C",
 229                                                 MBSTRING_ASC, "US", -1, -1, 0);
 230                                         *
 231                                         X509_NAME_add_entry_by_txt(name, "ST",
 232                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 233                                         *
 234                                         X509_NAME_add_entry_by_txt(name, "L",
 235                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 236                                         */
 237
 238                                         env = getenv("O");
 239                                         if (env == NULL)
 240                                                 env = "Organization name",
 241
 242                                         X509_NAME_add_entry_by_txt(
 243                                                 name, "O",
 244                                                 MBSTRING_ASC,
 245                                                 (unsigned char*)env,
 246                                                 -1, -1, 0
 247                                         );
 248
 249                                         env = getenv("OU");
 250                                         if (env == NULL)
 251                                                 env = "Citadel server";
 252
 253                                         X509_NAME_add_entry_by_txt(
 254                                                 name, "OU",
 255                                                 MBSTRING_ASC,
 256                                                 (unsigned char*)env,
 257                                                 -1, -1, 0
 258                                         );
 259
 260                                         env = getenv("CN");
 261                                         if (env == NULL)
 262                                                 env = "*";
 263
 264                                         X509_NAME_add_entry_by_txt(
 265                                                 name, "CN",
 266                                                 MBSTRING_ASC,
 267                                                 (unsigned char*)env,
 268                                                 -1, -1, 0
 269                                         );
 270
 271                                         X509_REQ_set_subject_name(req, name);
 272
 273                                         /* Sign the CSR */
 274                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 275                                                 syslog(3, "X509_REQ_sign(): error\n");
 276                                         }
 277                                         else {
 278                                                 /* Write it to disk. */
 279                                                 fp = fopen(CTDL_CSR_PATH, "w");
 280                                                 if (fp != NULL) {
 281                                                         chmod(CTDL_CSR_PATH, 0600);
 282                                                         PEM_write_X509_REQ(fp, req);
 283                                                         fclose(fp);
 284                                                 }
 285                                                 else {
 286                                                         syslog(3, "Cannot write key: %s\n", CTDL_CSR_PATH);
 287                                                         ShutDownWebcit();
 288                                                         exit(0);
 289                                                 }
 290                                         }
 291
 292                                         X509_REQ_free(req);
 293                                 }
 294                         }
 295
 296                         RSA_free(rsa);
 297                 }
 298
 299                 else {
 300                         syslog(3, "Unable to read private key.\n");
 301                 }
 302         }
 303
 304
 305
 306         /*
 307          * Generate a self-signed certificate if we don't have one.
 308          */
 309         if (access(CTDL_CER_PATH, R_OK) != 0) {
 310                 syslog(5, "Generating a self-signed certificate.\n");
 311
 312                 /* Same deal as before: always read the key from disk because
 313                  * it may or may not have just been generated.
 314                  */
 315                 fp = fopen(CTDL_KEY_PATH, "r");
 316                 if (fp) {
 317                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 318                         fclose(fp);
 319                 }
 320
 321                 /* This also holds true for the CSR. */
 322                 req = NULL;
 323                 cer = NULL;
 324                 pk = NULL;
 325                 if (rsa) {
 326                         if (pk=EVP_PKEY_new(), pk != NULL) {
 327                                 EVP_PKEY_assign_RSA(pk, rsa);
 328                         }
 329
 330                         fp = fopen(CTDL_CSR_PATH, "r");
 331                         if (fp) {
 332                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 333                                 fclose(fp);
 334                         }
 335
 336                         if (req) {
 337                                 if (cer = X509_new(), cer != NULL) {
 338
 339                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 340                                         X509_set_issuer_name(cer, req->req_info->subject);
 341                                         X509_set_subject_name(cer, req->req_info->subject);
 342                                         X509_gmtime_adj(X509_get_notBefore(cer), 0);
 343                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 344
 345                                         req_pkey = X509_REQ_get_pubkey(req);
 346                                         X509_set_pubkey(cer, req_pkey);
 347                                         EVP_PKEY_free(req_pkey);
 348
 349                                         /* Sign the cert */
 350                                         if (!X509_sign(cer, pk, EVP_md5())) {
 351                                                 syslog(3, "X509_sign(): error\n");
 352                                         }
 353                                         else {
 354                                                 /* Write it to disk. */
 355                                                 fp = fopen(CTDL_CER_PATH, "w");
 356                                                 if (fp != NULL) {
 357                                                         chmod(CTDL_CER_PATH, 0600);
 358                                                         PEM_write_X509(fp, cer);
 359                                                         fclose(fp);
 360                                                 }
 361                                                 else {
 362                                                         syslog(3, "Cannot write key: %s\n", CTDL_CER_PATH);
 363                                                         ShutDownWebcit();
 364                                                         exit(0);
 365                                                 }
 366                                         }
 367                                         X509_free(cer);
 368                                 }
 369                         }
 370
 371                         RSA_free(rsa);
 372                 }
 373         }
 374
 375         /*
 376          * Now try to bind to the key and certificate.
 377          * Note that we use SSL_CTX_use_certificate_chain_file() which allows
 378          * the certificate file to contain intermediate certificates.
 379          */
 380         SSL_CTX_use_certificate_chain_file(ssl_ctx, CTDL_CER_PATH);
 381         SSL_CTX_use_PrivateKey_file(ssl_ctx, CTDL_KEY_PATH, SSL_FILETYPE_PEM);
 382         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 383                 syslog(3, "Cannot install certificate: %s\n",
 384                                 ERR_reason_error_string(ERR_get_error()));
 385         }
 386
 387 }
 388
 389
 390 /*
 391  * starts SSL/TLS encryption for the current session.
 392  */
 393 int starttls(int sock) {
 394         int retval, bits, alg_bits;/*r; */
 395         SSL *newssl;
 396
 397         pthread_setspecific(ThreadSSL, NULL);
 398
 399         if (!ssl_ctx) {
 400                 return(1);
 401         }
 402         if (!(newssl = SSL_new(ssl_ctx))) {
 403                 syslog(3, "SSL_new failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 404                 return(2);
 405         }
 406         if (!(SSL_set_fd(newssl, sock))) {
 407                 syslog(3, "SSL_set_fd failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 408                 SSL_free(newssl);
 409                 return(3);
 410         }
 411         retval = SSL_accept(newssl);
 412         if (retval < 1) {
 413                 /*
 414                  * Can't notify the client of an error here; they will
 415                  * discover the problem at the SSL layer and should
 416                  * revert to unencrypted communications.
 417                  */
 418                 long errval;
 419                 const char *ssl_error_reason = NULL;
 420
 421                 errval = SSL_get_error(newssl, retval);
 422                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 423                 if (ssl_error_reason == NULL) {
 424                         syslog(3, "SSL_accept failed: errval=%ld, retval=%d %s\n", errval, retval, strerror(errval));
 425                 }
 426                 else {
 427                         syslog(3, "SSL_accept failed: %s\n", ssl_error_reason);
 428                 }
 429                 sleeeeeeeeeep(1);
 430                 retval = SSL_accept(newssl);
 431         }
 432         if (retval < 1) {
 433                 long errval;
 434                 const char *ssl_error_reason = NULL;
 435
 436                 errval = SSL_get_error(newssl, retval);
 437                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 438                 if (ssl_error_reason == NULL) {
 439                         syslog(3, "SSL_accept failed: errval=%ld, retval=%d (%s)\n", errval, retval, strerror(errval));
 440                 }
 441                 else {
 442                         syslog(3, "SSL_accept failed: %s\n", ssl_error_reason);
 443                 }
 444                 SSL_free(newssl);
 445                 newssl = NULL;
 446                 return(4);
 447         }
 448         else {
 449                 syslog(15, "SSL_accept success\n");
 450         }
 451         /*r = */BIO_set_close(newssl->rbio, BIO_NOCLOSE);
 452         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl), &alg_bits);
 453         syslog(15, "SSL/TLS using %s on %s (%d of %d bits)\n",
 454                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 455                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 456                 bits, alg_bits);
 457
 458         pthread_setspecific(ThreadSSL, newssl);
 459         syslog(15, "SSL started\n");
 460         return(0);
 461 }
 462
 463
 464
 465 /*
 466  * shuts down the TLS connection
 467  *
 468  * WARNING:  This may make your session vulnerable to a known plaintext
 469  * attack in the current implmentation.
 470  */
 471 void endtls(void)
 472 {
 473         /*SSL_CTX *ctx;*/
 474
 475         if (THREADSSL == NULL) return;
 476
 477         syslog(15, "Ending SSL/TLS\n");
 478         SSL_shutdown(THREADSSL);
 479         /*ctx = */SSL_get_SSL_CTX(THREADSSL);
 480
 481         /* I don't think this is needed, and it crashes the server anyway
 482          *
 483          *      if (ctx != NULL) {
 484          *              syslog(9, "Freeing CTX at %x\n", (int)ctx );
 485          *              SSL_CTX_free(ctx);
 486          *      }
 487          */
 488
 489         SSL_free(THREADSSL);
 490         pthread_setspecific(ThreadSSL, NULL);
 491 }
 492
 493
 494 /*
 495  * callback for OpenSSL mutex locks
 496  */
 497 void ssl_lock(int mode, int n, const char *file, int line)
 498 {
 499         if (mode & CRYPTO_LOCK) {
 500                 pthread_mutex_lock(SSLCritters[n]);
 501         }
 502         else {
 503                 pthread_mutex_unlock(SSLCritters[n]);
 504         }
 505 }
 506
 507 /*
 508  * Send binary data to the client encrypted.
 509  */
 510 void client_write_ssl(const StrBuf *Buf)
 511 {
 512         const char *buf;
 513         int retval;
 514         int nremain;
 515         long nbytes;
 516         char junk[1];
 517
 518         if (THREADSSL == NULL) return;
 519
 520         nbytes = nremain = StrLength(Buf);
 521         buf = ChrPtr(Buf);
 522
 523         while (nremain > 0) {
 524                 if (SSL_want_write(THREADSSL)) {
 525                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 526                                 syslog(9, "SSL_read in client_write: %s\n",
 527                                                 ERR_reason_error_string(ERR_get_error()));
 528                         }
 529                 }
 530                 retval = SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 531                 if (retval < 1) {
 532                         long errval;
 533
 534                         errval = SSL_get_error(THREADSSL, retval);
 535                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 536                                 sleeeeeeeeeep(1);
 537                                 continue;
 538                         }
 539                         syslog(9, "SSL_write got error %ld, ret %d\n", errval, retval);
 540                         if (retval == -1) {
 541                                 syslog(9, "errno is %d\n", errno);
 542                         }
 543                         endtls();
 544                         return;
 545                 }
 546                 nremain -= retval;
 547         }
 548 }
 549
 550
 551 /*
 552  * read data from the encrypted layer.
 553  */
 554 int client_read_sslbuffer(StrBuf *buf, int timeout)
 555 {
 556         char sbuf[16384]; /* OpenSSL communicates in 16k blocks, so let's speak its native tongue. */
 557         int rlen;
 558         char junk[1];
 559         SSL *pssl = THREADSSL;
 560
 561         if (pssl == NULL) return(-1);
 562
 563         while (1) {
 564                 if (SSL_want_read(pssl)) {
 565                         if ((SSL_write(pssl, junk, 0)) < 1) {
 566                                 syslog(9, "SSL_write in client_read\n");
 567                         }
 568                 }
 569                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 570                 if (rlen < 1) {
 571                         long errval;
 572
 573                         errval = SSL_get_error(pssl, rlen);
 574                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 575                                 sleeeeeeeeeep(1);
 576                                 continue;
 577                         }
 578                         syslog(9, "SSL_read got error %ld\n", errval);
 579                         endtls();
 580                         return (-1);
 581                 }
 582                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 583                 return rlen;
 584         }
 585         return (0);
 586 }
 587
 588 #endif                          /* HAVE_OPENSSL */