webcit/crypto.c

   1 /*
   2  * Copyright (c) 1996-2017 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 void ssl_lock(int mode, int n, const char *file, int line);
  33
  34 static unsigned long id_callback(void)
  35 {
  36         return (unsigned long) pthread_self();
  37 }
  38
  39 void shutdown_ssl(void)
  40 {
  41         ERR_free_strings();
  42
  43         /* Openssl requires these while shutdown.
  44          * Didn't find a way to get out of this clean.
  45          * int i, n = CRYPTO_num_locks();
  46          * for (i = 0; i < n; i++)
  47          *      free(SSLCritters[i]);
  48          * free(SSLCritters);
  49          */
  50 }
  51
  52
  53 void generate_key(char *keyfilename)
  54 {
  55         int ret = 0;
  56         RSA *rsa = NULL;
  57         BIGNUM *bne = NULL;
  58         int bits = 2048;
  59         unsigned long e = RSA_F4;
  60         FILE *fp;
  61
  62         if (access(keyfilename, R_OK) == 0) {
  63                 return;
  64         }
  65
  66         syslog(LOG_INFO, "crypto: generating RSA key pair");
  67
  68         // generate rsa key
  69         bne = BN_new();
  70         ret = BN_set_word(bne,e);
  71         if (ret != 1) {
  72                 goto free_all;
  73         }
  74
  75         rsa = RSA_new();
  76         ret = RSA_generate_key_ex(rsa, bits, bne, NULL);
  77         if (ret != 1) {
  78                 goto free_all;
  79         }
  80
  81         // write the key file
  82         fp = fopen(keyfilename, "w");
  83         if (fp != NULL) {
  84                 chmod(file_crpt_file_key, 0600);
  85                 if (PEM_write_RSAPrivateKey(fp, /* the file */
  86                                         rsa,    /* the key */
  87                                         NULL,   /* no enc */
  88                                         NULL,   /* no passphr */
  89                                         0,      /* no passphr */
  90                                         NULL,   /* no callbk */
  91                                         NULL    /* no callbk */
  92                 ) != 1) {
  93                         syslog(LOG_ERR, "crypto: cannot write key: %s", ERR_reason_error_string(ERR_get_error()));
  94                         unlink(keyfilename);
  95                 }
  96                 fclose(fp);
  97         }
  98
  99     // 4. free
 100 free_all:
 101     RSA_free(rsa);
 102     BN_free(bne);
 103 }
 104
 105
 106 /*
 107  * initialize ssl engine, load certs and initialize openssl internals
 108  */
 109 void init_ssl(void)
 110 {
 111         const SSL_METHOD *ssl_method;
 112         RSA *rsa=NULL;
 113         X509_REQ *req = NULL;
 114         X509 *cer = NULL;
 115         EVP_PKEY *pk = NULL;
 116         EVP_PKEY *req_pkey = NULL;
 117         X509_NAME *name = NULL;
 118         FILE *fp;
 119         char buf[SIZ];
 120         int rv = 0;
 121
 122 #ifndef OPENSSL_NO_EGD
 123         if (!access("/var/run/egd-pool", F_OK)) {
 124                 RAND_egd("/var/run/egd-pool");
 125         }
 126 #endif
 127
 128         if (!RAND_status()) {
 129                 syslog(LOG_WARNING, "PRNG not adequately seeded, won't do SSL/TLS\n");
 130                 return;
 131         }
 132         SSLCritters = malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
 133         if (!SSLCritters) {
 134                 syslog(LOG_ERR, "citserver: can't allocate memory!!\n");
 135                 /* Nothing's been initialized, just die */
 136                 ShutDownWebcit();
 137                 exit(WC_EXIT_SSL);
 138         } else {
 139                 int a;
 140
 141                 for (a = 0; a < CRYPTO_num_locks(); a++) {
 142                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
 143                         if (!SSLCritters[a]) {
 144                                 syslog(LOG_ERR,
 145                                         "citserver: can't allocate memory!!\n");
 146                                 /** Nothing's been initialized, just die */
 147                                 ShutDownWebcit();
 148                                 exit(WC_EXIT_SSL);
 149                         }
 150                         pthread_mutex_init(SSLCritters[a], NULL);
 151                 }
 152         }
 153
 154         /*
 155          * Initialize SSL transport layer
 156          */
 157         SSL_library_init();
 158         SSL_load_error_strings();
 159         ssl_method = SSLv23_server_method();
 160         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 161                 syslog(LOG_WARNING, "SSL_CTX_new failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 162                 return;
 163         }
 164
 165         syslog(LOG_INFO, "Requesting cipher list: %s\n", ssl_cipher_list);
 166         if (!(SSL_CTX_set_cipher_list(ssl_ctx, ssl_cipher_list))) {
 167                 syslog(LOG_WARNING, "SSL_CTX_set_cipher_list failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 168                 return;
 169         }
 170
 171         CRYPTO_set_locking_callback(ssl_lock);
 172         CRYPTO_set_id_callback(id_callback);
 173
 174         /*
 175          * Get our certificates in order. (FIXME: dirify. this is a setup job.)
 176          * First, create the key/cert directory if it's not there already...
 177          */
 178         mkdir(CTDL_CRYPTO_DIR, 0700);
 179
 180         /*
 181          * Before attempting to generate keys/certificates, first try
 182          * link to them from the Citadel server if it's on the same host.
 183          * We ignore any error return because it either meant that there
 184          * was nothing in Citadel to link from (in which case we just
 185          * generate new files) or the target files already exist (which
 186          * is not fatal either).
 187          */
 188         if (!strcasecmp(ctdlhost, "uds")) {
 189                 sprintf(buf, "%s/keys/citadel.key", ctdlport);
 190                 rv = symlink(buf, CTDL_KEY_PATH);
 191                 if (!rv) syslog(LOG_DEBUG, "%s\n", strerror(errno));
 192                 sprintf(buf, "%s/keys/citadel.csr", ctdlport);
 193                 rv = symlink(buf, CTDL_CSR_PATH);
 194                 if (!rv) syslog(LOG_DEBUG, "%s\n", strerror(errno));
 195                 sprintf(buf, "%s/keys/citadel.cer", ctdlport);
 196                 rv = symlink(buf, CTDL_CER_PATH);
 197                 if (!rv) syslog(LOG_DEBUG, "%s\n", strerror(errno));
 198         }
 199
 200         /*
 201          * If we still don't have a private key, generate one.
 202          */
 203         generate_key(CTDL_KEY_PATH);
 204
 205         /*
 206          * If there is no certificate file on disk, we will be generating a self-signed certificate
 207          * in the next step.  Therefore, if we have neither a CSR nor a certificate, generate
 208          * the CSR in this step so that the next step may commence.
 209          */
 210         if ( (access(CTDL_CER_PATH, R_OK) != 0) && (access(CTDL_CSR_PATH, R_OK) != 0) ) {
 211                 syslog(LOG_INFO, "Generating a certificate signing request.\n");
 212
 213                 /*
 214                  * Read our key from the file.  No, we don't just keep this
 215                  * in memory from the above key-generation function, because
 216                  * there is the possibility that the key was already on disk
 217                  * and we didn't just generate it now.
 218                  */
 219                 fp = fopen(CTDL_KEY_PATH, "r");
 220                 if (fp) {
 221                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 222                         fclose(fp);
 223                 }
 224
 225                 if (rsa) {
 226
 227                         /** Create a public key from the private key */
 228                         if (pk=EVP_PKEY_new(), pk != NULL) {
 229                                 EVP_PKEY_assign_RSA(pk, rsa);
 230                                 if (req = X509_REQ_new(), req != NULL) {
 231                                         const char *env;
 232                                         /* Set the public key */
 233                                         X509_REQ_set_pubkey(req, pk);
 234                                         X509_REQ_set_version(req, 0L);
 235
 236                                         name = X509_REQ_get_subject_name(req);
 237
 238                                         /* Tell it who we are */
 239
 240                                         /*
 241                                          * We used to add these fields to the subject, but
 242                                          * now we don't.  Someone doing this for real isn't
 243                                          * going to use the webcit-generated CSR anyway.
 244                                          *
 245                                         X509_NAME_add_entry_by_txt(name, "C",
 246                                                 MBSTRING_ASC, "US", -1, -1, 0);
 247                                         *
 248                                         X509_NAME_add_entry_by_txt(name, "ST",
 249                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 250                                         *
 251                                         X509_NAME_add_entry_by_txt(name, "L",
 252                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 253                                         */
 254
 255                                         env = getenv("O");
 256                                         if (env == NULL)
 257                                                 env = "Organization name",
 258
 259                                         X509_NAME_add_entry_by_txt(
 260                                                 name, "O",
 261                                                 MBSTRING_ASC,
 262                                                 (unsigned char*)env,
 263                                                 -1, -1, 0
 264                                         );
 265
 266                                         env = getenv("OU");
 267                                         if (env == NULL)
 268                                                 env = "Citadel server";
 269
 270                                         X509_NAME_add_entry_by_txt(
 271                                                 name, "OU",
 272                                                 MBSTRING_ASC,
 273                                                 (unsigned char*)env,
 274                                                 -1, -1, 0
 275                                         );
 276
 277                                         env = getenv("CN");
 278                                         if (env == NULL)
 279                                                 env = "*";
 280
 281                                         X509_NAME_add_entry_by_txt(
 282                                                 name, "CN",
 283                                                 MBSTRING_ASC,
 284                                                 (unsigned char*)env,
 285                                                 -1, -1, 0
 286                                         );
 287
 288                                         X509_REQ_set_subject_name(req, name);
 289
 290                                         /* Sign the CSR */
 291                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 292                                                 syslog(LOG_WARNING, "X509_REQ_sign(): error\n");
 293                                         }
 294                                         else {
 295                                                 /* Write it to disk. */
 296                                                 fp = fopen(CTDL_CSR_PATH, "w");
 297                                                 if (fp != NULL) {
 298                                                         chmod(CTDL_CSR_PATH, 0600);
 299                                                         PEM_write_X509_REQ(fp, req);
 300                                                         fclose(fp);
 301                                                 }
 302                                                 else {
 303                                                         syslog(LOG_WARNING, "Cannot write key: %s\n", CTDL_CSR_PATH);
 304                                                         ShutDownWebcit();
 305                                                         exit(0);
 306                                                 }
 307                                         }
 308
 309                                         X509_REQ_free(req);
 310                                 }
 311                         }
 312
 313                         RSA_free(rsa);
 314                 }
 315
 316                 else {
 317                         syslog(LOG_WARNING, "Unable to read private key.\n");
 318                 }
 319         }
 320
 321
 322
 323         /*
 324          * Generate a self-signed certificate if we don't have one.
 325          */
 326         if (access(CTDL_CER_PATH, R_OK) != 0) {
 327                 syslog(LOG_INFO, "Generating a self-signed certificate.\n");
 328
 329                 /* Same deal as before: always read the key from disk because
 330                  * it may or may not have just been generated.
 331                  */
 332                 fp = fopen(CTDL_KEY_PATH, "r");
 333                 if (fp) {
 334                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 335                         fclose(fp);
 336                 }
 337
 338                 /* This also holds true for the CSR. */
 339                 req = NULL;
 340                 cer = NULL;
 341                 pk = NULL;
 342                 if (rsa) {
 343                         if (pk=EVP_PKEY_new(), pk != NULL) {
 344                                 EVP_PKEY_assign_RSA(pk, rsa);
 345                         }
 346
 347                         fp = fopen(CTDL_CSR_PATH, "r");
 348                         if (fp) {
 349                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 350                                 fclose(fp);
 351                         }
 352
 353                         if (req) {
 354                                 if (cer = X509_new(), cer != NULL) {
 355
 356                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 357                                         X509_set_issuer_name(cer, X509_REQ_get_subject_name(req));
 358                                         X509_set_subject_name(cer, X509_REQ_get_subject_name(req));
 359                                         X509_gmtime_adj(X509_get_notBefore(cer), 0);
 360                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 361
 362                                         req_pkey = X509_REQ_get_pubkey(req);
 363                                         X509_set_pubkey(cer, req_pkey);
 364                                         EVP_PKEY_free(req_pkey);
 365
 366                                         /* Sign the cert */
 367                                         if (!X509_sign(cer, pk, EVP_md5())) {
 368                                                 syslog(LOG_WARNING, "X509_sign(): error\n");
 369                                         }
 370                                         else {
 371                                                 /* Write it to disk. */
 372                                                 fp = fopen(CTDL_CER_PATH, "w");
 373                                                 if (fp != NULL) {
 374                                                         chmod(CTDL_CER_PATH, 0600);
 375                                                         PEM_write_X509(fp, cer);
 376                                                         fclose(fp);
 377                                                 }
 378                                                 else {
 379                                                         syslog(LOG_WARNING, "Cannot write key: %s\n", CTDL_CER_PATH);
 380                                                         ShutDownWebcit();
 381                                                         exit(0);
 382                                                 }
 383                                         }
 384                                         X509_free(cer);
 385                                 }
 386                         }
 387
 388                         RSA_free(rsa);
 389                 }
 390         }
 391
 392         /*
 393          * Now try to bind to the key and certificate.
 394          * Note that we use SSL_CTX_use_certificate_chain_file() which allows
 395          * the certificate file to contain intermediate certificates.
 396          */
 397         SSL_CTX_use_certificate_chain_file(ssl_ctx, CTDL_CER_PATH);
 398         SSL_CTX_use_PrivateKey_file(ssl_ctx, CTDL_KEY_PATH, SSL_FILETYPE_PEM);
 399         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 400                 syslog(LOG_WARNING, "Cannot install certificate: %s\n",
 401                                 ERR_reason_error_string(ERR_get_error()));
 402         }
 403
 404 }
 405
 406
 407 /*
 408  * starts SSL/TLS encryption for the current session.
 409  */
 410 int starttls(int sock) {
 411         int retval, bits, alg_bits;/*r; */
 412         SSL *newssl;
 413
 414         pthread_setspecific(ThreadSSL, NULL);
 415
 416         if (!ssl_ctx) {
 417                 return(1);
 418         }
 419         if (!(newssl = SSL_new(ssl_ctx))) {
 420                 syslog(LOG_WARNING, "SSL_new failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 421                 return(2);
 422         }
 423         if (!(SSL_set_fd(newssl, sock))) {
 424                 syslog(LOG_WARNING, "SSL_set_fd failed: %s\n", ERR_reason_error_string(ERR_get_error()));
 425                 SSL_free(newssl);
 426                 return(3);
 427         }
 428         retval = SSL_accept(newssl);
 429         if (retval < 1) {
 430                 /*
 431                  * Can't notify the client of an error here; they will
 432                  * discover the problem at the SSL layer and should
 433                  * revert to unencrypted communications.
 434                  */
 435                 long errval;
 436                 const char *ssl_error_reason = NULL;
 437
 438                 errval = SSL_get_error(newssl, retval);
 439                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 440                 if (ssl_error_reason == NULL) {
 441                         syslog(LOG_WARNING, "SSL_accept failed: errval=%ld, retval=%d %s\n", errval, retval, strerror(errval));
 442                 }
 443                 else {
 444                         syslog(LOG_WARNING, "SSL_accept failed: %s\n", ssl_error_reason);
 445                 }
 446                 sleeeeeeeeeep(1);
 447                 retval = SSL_accept(newssl);
 448         }
 449         if (retval < 1) {
 450                 long errval;
 451                 const char *ssl_error_reason = NULL;
 452
 453                 errval = SSL_get_error(newssl, retval);
 454                 ssl_error_reason = ERR_reason_error_string(ERR_get_error());
 455                 if (ssl_error_reason == NULL) {
 456                         syslog(LOG_WARNING, "SSL_accept failed: errval=%ld, retval=%d (%s)\n", errval, retval, strerror(errval));
 457                 }
 458                 else {
 459                         syslog(LOG_WARNING, "SSL_accept failed: %s\n", ssl_error_reason);
 460                 }
 461                 SSL_free(newssl);
 462                 newssl = NULL;
 463                 return(4);
 464         }
 465         else {
 466                 syslog(LOG_INFO, "SSL_accept success\n");
 467         }
 468         /*r = */BIO_set_close(SSL_get_rbio(newssl), BIO_NOCLOSE);
 469         bits = SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl), &alg_bits);
 470         syslog(LOG_INFO, "SSL/TLS using %s on %s (%d of %d bits)\n",
 471                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 472                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 473                 bits, alg_bits);
 474
 475         pthread_setspecific(ThreadSSL, newssl);
 476         syslog(LOG_INFO, "SSL started\n");
 477         return(0);
 478 }
 479
 480
 481
 482 /*
 483  * shuts down the TLS connection
 484  *
 485  * WARNING:  This may make your session vulnerable to a known plaintext
 486  * attack in the current implmentation.
 487  */
 488 void endtls(void)
 489 {
 490         /*SSL_CTX *ctx;*/
 491
 492         if (THREADSSL == NULL) return;
 493
 494         syslog(LOG_INFO, "Ending SSL/TLS\n");
 495         SSL_shutdown(THREADSSL);
 496         /*ctx = */SSL_get_SSL_CTX(THREADSSL);
 497
 498         /* I don't think this is needed, and it crashes the server anyway
 499          *
 500          *      if (ctx != NULL) {
 501          *              syslog(LOG_DEBUG, "Freeing CTX at %x\n", (int)ctx );
 502          *              SSL_CTX_free(ctx);
 503          *      }
 504          */
 505
 506         SSL_free(THREADSSL);
 507         pthread_setspecific(ThreadSSL, NULL);
 508 }
 509
 510
 511 /*
 512  * callback for OpenSSL mutex locks
 513  */
 514 void ssl_lock(int mode, int n, const char *file, int line)
 515 {
 516         if (mode & CRYPTO_LOCK) {
 517                 pthread_mutex_lock(SSLCritters[n]);
 518         }
 519         else {
 520                 pthread_mutex_unlock(SSLCritters[n]);
 521         }
 522 }
 523
 524 /*
 525  * Send binary data to the client encrypted.
 526  */
 527 int client_write_ssl(const StrBuf *Buf)
 528 {
 529         const char *buf;
 530         int retval;
 531         int nremain;
 532         long nbytes;
 533         char junk[1];
 534
 535         if (THREADSSL == NULL) return -1;
 536
 537         nbytes = nremain = StrLength(Buf);
 538         buf = ChrPtr(Buf);
 539
 540         while (nremain > 0) {
 541                 if (SSL_want_write(THREADSSL)) {
 542                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 543                                 syslog(LOG_WARNING, "SSL_read in client_write: %s\n",
 544                                                 ERR_reason_error_string(ERR_get_error()));
 545                         }
 546                 }
 547                 retval = SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 548                 if (retval < 1) {
 549                         long errval;
 550
 551                         errval = SSL_get_error(THREADSSL, retval);
 552                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 553                                 sleeeeeeeeeep(1);
 554                                 continue;
 555                         }
 556                         syslog(LOG_WARNING, "SSL_write got error %ld, ret %d\n", errval, retval);
 557                         if (retval == -1) {
 558                                 syslog(LOG_WARNING, "errno is %d\n", errno);
 559                         }
 560                         endtls();
 561                         return -1;
 562                 }
 563                 nremain -= retval;
 564         }
 565         return 0;
 566 }
 567
 568
 569 /*
 570  * read data from the encrypted layer.
 571  */
 572 int client_read_sslbuffer(StrBuf *buf, int timeout)
 573 {
 574         char sbuf[16384]; /* OpenSSL communicates in 16k blocks, so let's speak its native tongue. */
 575         int rlen;
 576         char junk[1];
 577         SSL *pssl = THREADSSL;
 578
 579         if (pssl == NULL) return(-1);
 580
 581         while (1) {
 582                 if (SSL_want_read(pssl)) {
 583                         if ((SSL_write(pssl, junk, 0)) < 1) {
 584                                 syslog(LOG_WARNING, "SSL_write in client_read\n");
 585                         }
 586                 }
 587                 rlen = SSL_read(pssl, sbuf, sizeof(sbuf));
 588                 if (rlen < 1) {
 589                         long errval;
 590
 591                         errval = SSL_get_error(pssl, rlen);
 592                         if (errval == SSL_ERROR_WANT_READ || errval == SSL_ERROR_WANT_WRITE) {
 593                                 sleeeeeeeeeep(1);
 594                                 continue;
 595                         }
 596                         syslog(LOG_WARNING, "SSL_read got error %ld\n", errval);
 597                         endtls();
 598                         return (-1);
 599                 }
 600                 StrBufAppendBufPlain(buf, sbuf, rlen, 0);
 601                 return rlen;
 602         }
 603         return (0);
 604 }
 605
 606 #endif                          /* HAVE_OPENSSL */