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