webcit/crypto.c

   1 /* $Id$ */
   2
   3 #ifdef HAVE_OPENSSL
   4
   5
   6 #include <stdlib.h>
   7 #include <unistd.h>
   8 #include <string.h>
   9 #include <sys/stat.h>
  10 #include <sys/types.h>
  11 #include <pthread.h>
  12
  13 #include <sys/time.h>
  14 #include "webcit.h"
  15 #include "webserver.h"
  16
  17 #define CTDL_CRYPTO_DIR         WEBCITDIR "/keys"
  18 #define CTDL_KEY_PATH           CTDL_CRYPTO_DIR "/citadel.key"
  19 #define CTDL_CSR_PATH           CTDL_CRYPTO_DIR "/citadel.csr"
  20 #define CTDL_CER_PATH           CTDL_CRYPTO_DIR "/citadel.cer"
  21 #define SIGN_DAYS               365
  22
  23
  24 /* Shared Diffie-Hellman parameters */
  25 #define DH_P            "1A74527AEE4EE2568E85D4FB2E65E18C9394B9C80C42507D7A6A0DBE9A9A54B05A9A96800C34C7AA5297095B69C88901EEFD127F969DCA26A54C0E0B5C5473EBAEB00957D2633ECAE3835775425DE66C0DE6D024DBB17445E06E6B0C78415E589B8814F08531D02FD43778451E7685541079CFFB79EF0D26EFEEBBB69D1E80383"
  26 #define DH_G            "2"
  27 #define DH_L            1024
  28
  29 SSL_CTX *ssl_ctx;               /* SSL context */
  30 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  31
  32 pthread_key_t ThreadSSL;        /* Per-thread SSL context */
  33
  34 static unsigned long id_callback(void)
  35 {
  36         return (unsigned long) pthread_self();
  37 }
  38
  39  /*
  40   * Set up the cert things on the server side. We do need both the
  41   * private key (in key_file) and the cert (in cert_file).
  42   * Both files may be identical.
  43   *
  44   * This function is taken from OpenSSL apps/s_cb.c
  45   */
  46
  47 static int ctdl_install_certificate(SSL_CTX * ctx,
  48                           const char *cert_file, const char *key_file)
  49 {
  50         if (cert_file != NULL) {
  51                 if (SSL_CTX_use_certificate_file(ctx, cert_file,
  52                                                  SSL_FILETYPE_PEM) <= 0) {
  53                         lprintf(3, "unable to get certificate from '%s'",
  54                                 cert_file);
  55                         return (0);
  56                 }
  57                 if (key_file == NULL)
  58                         key_file = cert_file;
  59                 if (SSL_CTX_use_PrivateKey_file(ctx, key_file,
  60                                                 SSL_FILETYPE_PEM) <= 0) {
  61                         lprintf(3, "unable to get private key from '%s'",
  62                                 key_file);
  63                         return (0);
  64                 }
  65                 /* Now we know that a key and cert have been set against
  66                  * the SSL context */
  67                 if (!SSL_CTX_check_private_key(ctx)) {
  68                         lprintf(3,
  69                                 "Private key does not match the certificate public key");
  70                         return (0);
  71                 }
  72         }
  73         return (1);
  74 }
  75
  76
  77 void init_ssl(void)
  78 {
  79         SSL_METHOD *ssl_method;
  80         DH *dh;
  81         RSA *rsa=NULL;
  82         X509_REQ *req = NULL;
  83         X509 *cer = NULL;
  84         EVP_PKEY *pk = NULL;
  85         EVP_PKEY *req_pkey = NULL;
  86         X509_NAME *name = NULL;
  87         FILE *fp;
  88
  89         if (!access("/var/run/egd-pool", F_OK))
  90                 RAND_egd("/var/run/egd-pool");
  91
  92         if (!RAND_status()) {
  93                 lprintf(3,
  94                         "PRNG not adequately seeded, won't do SSL/TLS\n");
  95                 return;
  96         }
  97         SSLCritters =
  98             malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  99         if (!SSLCritters) {
 100                 lprintf(1, "citserver: can't allocate memory!!\n");
 101                 /* Nothing's been initialized, just die */
 102                 exit(1);
 103         } else {
 104                 int a;
 105
 106                 for (a = 0; a < CRYPTO_num_locks(); a++) {
 107                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
 108                         if (!SSLCritters[a]) {
 109                                 lprintf(1,
 110                                         "citserver: can't allocate memory!!\n");
 111                                 /* Nothing's been initialized, just die */
 112                                 exit(1);
 113                         }
 114                         pthread_mutex_init(SSLCritters[a], NULL);
 115                 }
 116         }
 117
 118         /*
 119          * Initialize SSL transport layer
 120          */
 121         SSL_library_init();
 122         OpenSSL_add_all_algorithms();
 123         SSL_load_error_strings();
 124         ssl_method = SSLv2_server_method();
 125         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
 126                 lprintf(3, "SSL_CTX_new failed: %s\n",
 127                         ERR_reason_error_string(ERR_get_error()));
 128                 return;
 129         }
 130
 131         CRYPTO_set_locking_callback(ssl_lock);
 132         CRYPTO_set_id_callback(id_callback);
 133
 134         /* Load DH parameters into the context */
 135         dh = DH_new();
 136         if (!dh) {
 137                 lprintf(3, "init_ssl() can't allocate a DH object: %s\n",
 138                         ERR_reason_error_string(ERR_get_error()));
 139                 SSL_CTX_free(ssl_ctx);
 140                 ssl_ctx = NULL;
 141                 return;
 142         }
 143         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 144                 lprintf(3, "init_ssl() can't assign DH_P: %s\n",
 145                         ERR_reason_error_string(ERR_get_error()));
 146                 SSL_CTX_free(ssl_ctx);
 147                 ssl_ctx = NULL;
 148                 return;
 149         }
 150         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 151                 lprintf(3, "init_ssl() can't assign DH_G: %s\n",
 152                         ERR_reason_error_string(ERR_get_error()));
 153                 SSL_CTX_free(ssl_ctx);
 154                 ssl_ctx = NULL;
 155                 return;
 156         }
 157         dh->length = DH_L;
 158         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 159         DH_free(dh);
 160
 161         /* Get our certificates in order.
 162          * First, create the key/cert directory if it's not there already...
 163          */
 164         mkdir(CTDL_CRYPTO_DIR, 0700);
 165
 166         /*
 167          * Generate a key pair if we don't have one.
 168          */
 169         if (access(CTDL_KEY_PATH, R_OK) != 0) {
 170                 lprintf(5, "Generating RSA key pair.\n");
 171                 rsa = RSA_generate_key(1024,    /* modulus size */
 172                                         65537,  /* exponent */
 173                                         NULL,   /* no callback */
 174                                         NULL);  /* no callback */
 175                 if (rsa == NULL) {
 176                         lprintf(3, "Key generation failed: %s\n",
 177                                 ERR_reason_error_string(ERR_get_error()));
 178                 }
 179                 if (rsa != NULL) {
 180                         fp = fopen(CTDL_KEY_PATH, "w");
 181                         if (fp != NULL) {
 182                                 chmod(CTDL_KEY_PATH, 0600);
 183                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 184                                                         rsa,    /* the key */
 185                                                         NULL,   /* no enc */
 186                                                         NULL,   /* no passphr */
 187                                                         0,      /* no passphr */
 188                                                         NULL,   /* no callbk */
 189                                                         NULL    /* no callbk */
 190                                 ) != 1) {
 191                                         lprintf(3, "Cannot write key: %s\n",
 192                                                 ERR_reason_error_string(ERR_get_error()));
 193                                         unlink(CTDL_KEY_PATH);
 194                                 }
 195                                 fclose(fp);
 196                         }
 197                         RSA_free(rsa);
 198                 }
 199         }
 200
 201         /*
 202          * Generate a CSR if we don't have one.
 203          */
 204         if (access(CTDL_CSR_PATH, R_OK) != 0) {
 205                 lprintf(5, "Generating a certificate signing request.\n");
 206
 207                 /*
 208                  * Read our key from the file.  No, we don't just keep this
 209                  * in memory from the above key-generation function, because
 210                  * there is the possibility that the key was already on disk
 211                  * and we didn't just generate it now.
 212                  */
 213                 fp = fopen(CTDL_KEY_PATH, "r");
 214                 if (fp) {
 215                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 216                         fclose(fp);
 217                 }
 218
 219                 if (rsa) {
 220
 221                         /* Create a public key from the private key */
 222                         if (pk=EVP_PKEY_new(), pk != NULL) {
 223                                 EVP_PKEY_assign_RSA(pk, rsa);
 224                                 if (req = X509_REQ_new(), req != NULL) {
 225
 226                                         /* Set the public key */
 227                                         X509_REQ_set_pubkey(req, pk);
 228                                         X509_REQ_set_version(req, 0L);
 229
 230                                         name = X509_REQ_get_subject_name(req);
 231
 232                                         /* Tell it who we are */
 233
 234                                         /*
 235                                         X509_NAME_add_entry_by_txt(name, "C",
 236                                                 MBSTRING_ASC, "US", -1, -1, 0);
 237
 238                                         X509_NAME_add_entry_by_txt(name, "ST",
 239                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 240
 241                                         X509_NAME_add_entry_by_txt(name, "L",
 242                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 243                                         */
 244
 245                                         X509_NAME_add_entry_by_txt(name, "O",
 246                                                 MBSTRING_ASC, "FIXME.FIXME.org", -1, -1, 0);
 247
 248                                         X509_NAME_add_entry_by_txt(name, "OU",
 249                                                 MBSTRING_ASC, "Citadel server", -1, -1, 0);
 250
 251                                         X509_NAME_add_entry_by_txt(name, "CN",
 252                                                 MBSTRING_ASC, "FIXME.FIXME.org", -1, -1, 0);
 253
 254                                         X509_REQ_set_subject_name(req, name);
 255
 256                                         /* Sign the CSR */
 257                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 258                                                 lprintf(3, "X509_REQ_sign(): error\n");
 259                                         }
 260                                         else {
 261                                                 /* Write it to disk. */
 262                                                 fp = fopen(CTDL_CSR_PATH, "w");
 263                                                 if (fp != NULL) {
 264                                                         chmod(CTDL_CSR_PATH, 0600);
 265                                                         PEM_write_X509_REQ(fp, req);
 266                                                         fclose(fp);
 267                                                 }
 268                                         }
 269
 270                                         X509_REQ_free(req);
 271                                 }
 272                         }
 273
 274                         RSA_free(rsa);
 275                 }
 276
 277                 else {
 278                         lprintf(3, "Unable to read private key.\n");
 279                 }
 280         }
 281
 282
 283
 284         /*
 285          * Generate a self-signed certificate if we don't have one.
 286          */
 287         if (access(CTDL_CER_PATH, R_OK) != 0) {
 288                 lprintf(5, "Generating a self-signed certificate.\n");
 289
 290                 /* Same deal as before: always read the key from disk because
 291                  * it may or may not have just been generated.
 292                  */
 293                 fp = fopen(CTDL_KEY_PATH, "r");
 294                 if (fp) {
 295                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 296                         fclose(fp);
 297                 }
 298
 299                 /* This also holds true for the CSR. */
 300                 req = NULL;
 301                 cer = NULL;
 302                 pk = NULL;
 303                 if (rsa) {
 304                         if (pk=EVP_PKEY_new(), pk != NULL) {
 305                                 EVP_PKEY_assign_RSA(pk, rsa);
 306                         }
 307
 308                         fp = fopen(CTDL_CSR_PATH, "r");
 309                         if (fp) {
 310                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 311                                 fclose(fp);
 312                         }
 313
 314                         if (req) {
 315                                 if (cer = X509_new(), cer != NULL) {
 316
 317                                         X509_set_issuer_name(cer, req->req_info->subject);
 318                                         X509_set_subject_name(cer, req->req_info->subject);
 319                                         X509_gmtime_adj(X509_get_notBefore(cer),0);
 320                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 321                                         req_pkey = X509_REQ_get_pubkey(req);
 322                                         X509_set_pubkey(cer, req_pkey);
 323                                         EVP_PKEY_free(req_pkey);
 324
 325                                         /* Sign the cert */
 326                                         if (!X509_sign(cer, pk, EVP_md5())) {
 327                                                 lprintf(3, "X509_sign(): error\n");
 328                                         }
 329                                         else {
 330                                                 /* Write it to disk. */
 331                                                 fp = fopen(CTDL_CER_PATH, "w");
 332                                                 if (fp != NULL) {
 333                                                         chmod(CTDL_CER_PATH, 0600);
 334                                                         PEM_write_X509(fp, cer);
 335                                                         fclose(fp);
 336                                                 }
 337                                         }
 338                                         X509_free(cer);
 339                                 }
 340                         }
 341
 342                         RSA_free(rsa);
 343                 }
 344         }
 345
 346
 347         /*
 348          * Now try to bind to the key and certificate.
 349          */
 350         if (ctdl_install_certificate(ssl_ctx,
 351                         CTDL_CER_PATH,
 352                         CTDL_KEY_PATH) != 1)
 353         {
 354                 lprintf(3, "Cannot install certificate: %s\n",
 355                                 ERR_reason_error_string(ERR_get_error()));
 356         }
 357
 358 }
 359
 360
 361 /*
 362  * starttls() starts SSL/TLS encryption for the current session.
 363  */
 364 int starttls(int sock) {
 365         int retval, bits, alg_bits;
 366         SSL *newssl;
 367
 368         pthread_setspecific(ThreadSSL, NULL);
 369
 370         if (!ssl_ctx) {
 371                 return(1);
 372         }
 373         if (!(newssl = SSL_new(ssl_ctx))) {
 374                 lprintf(3, "SSL_new failed: %s\n",
 375                                 ERR_reason_error_string(ERR_get_error()));
 376                 return(2);
 377         }
 378         if (!(SSL_set_fd(newssl, sock))) {
 379                 lprintf(3, "SSL_set_fd failed: %s\n",
 380                         ERR_reason_error_string(ERR_get_error()));
 381                 SSL_free(newssl);
 382                 return(3);
 383         }
 384         retval = SSL_accept(newssl);
 385         if (retval < 1) {
 386                 /*
 387                  * Can't notify the client of an error here; they will
 388                  * discover the problem at the SSL layer and should
 389                  * revert to unencrypted communications.
 390                  */
 391                 long errval;
 392
 393                 errval = SSL_get_error(newssl, retval);
 394                 lprintf(3, "SSL_accept failed: %s\n",
 395                         ERR_reason_error_string(ERR_get_error()));
 396                 SSL_free(newssl);
 397                 newssl = NULL;
 398                 return(4);
 399         }
 400         BIO_set_close(newssl->rbio, BIO_NOCLOSE);
 401         bits =
 402             SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl),
 403                                 &alg_bits);
 404         lprintf(5, "SSL/TLS using %s on %s (%d of %d bits)\n",
 405                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 406                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 407                 bits, alg_bits);
 408
 409         pthread_setspecific(ThreadSSL, newssl);
 410         return(0);
 411 }
 412
 413
 414
 415 /*
 416  * endtls() shuts down the TLS connection
 417  *
 418  * WARNING:  This may make your session vulnerable to a known plaintext
 419  * attack in the current implmentation.
 420  */
 421 void endtls(void)
 422 {
 423         lprintf(5, "Ending SSL/TLS\n");
 424         SSL_shutdown(THREADSSL);
 425         SSL_free(THREADSSL);
 426         pthread_setspecific(ThreadSSL, NULL);
 427 }
 428
 429
 430 /*
 431  * ssl_lock() callback for OpenSSL mutex locks
 432  */
 433 void ssl_lock(int mode, int n, const char *file, int line)
 434 {
 435         if (mode & CRYPTO_LOCK)
 436                 pthread_mutex_lock(SSLCritters[n]);
 437         else
 438                 pthread_mutex_unlock(SSLCritters[n]);
 439 }
 440
 441 /*
 442  * client_write_ssl() Send binary data to the client encrypted.
 443  */
 444 void client_write_ssl(char *buf, int nbytes)
 445 {
 446         int retval;
 447         int nremain;
 448         char junk[1];
 449
 450         nremain = nbytes;
 451
 452         while (nremain > 0) {
 453                 if (SSL_want_write(THREADSSL)) {
 454                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 455                                 lprintf(9, "SSL_read in client_write: %s\n", ERR_reason_error_string(ERR_get_error()));
 456                         }
 457                 }
 458                 retval =
 459                     SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 460                 if (retval < 1) {
 461                         long errval;
 462
 463                         errval = SSL_get_error(THREADSSL, retval);
 464                         if (errval == SSL_ERROR_WANT_READ ||
 465                             errval == SSL_ERROR_WANT_WRITE) {
 466                                 sleep(1);
 467                                 continue;
 468                         }
 469                         lprintf(9, "SSL_write got error %ld, ret %d\n", errval, retval);
 470                         if (retval == -1)
 471                                 lprintf(9, "errno is %d\n", errno);
 472                         endtls();
 473                         client_write(&buf[nbytes - nremain], nremain);
 474                         return;
 475                 }
 476                 nremain -= retval;
 477         }
 478 }
 479
 480
 481 /*
 482  * client_read_ssl() - read data from the encrypted layer.
 483  */
 484 int client_read_ssl(char *buf, int bytes, int timeout)
 485 {
 486 #if 0
 487         fd_set rfds;
 488         struct timeval tv;
 489         int retval;
 490         int s;
 491 #endif
 492         int len, rlen;
 493         char junk[1];
 494
 495         len = 0;
 496         while (len < bytes) {
 497 #if 0
 498                 /*
 499                  * This code is disabled because we don't need it when
 500                  * using blocking reads (which we are). -IO
 501                  */
 502                 FD_ZERO(&rfds);
 503                 s = BIO_get_fd(THREADSSL->rbio, NULL);
 504                 FD_SET(s, &rfds);
 505                 tv.tv_sec = timeout;
 506                 tv.tv_usec = 0;
 507
 508                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 509
 510                 if (FD_ISSET(s, &rfds) == 0) {
 511                         return (0);
 512                 }
 513
 514 #endif
 515                 if (SSL_want_read(THREADSSL)) {
 516                         if ((SSL_write(THREADSSL, junk, 0)) < 1) {
 517                                 lprintf(9, "SSL_write in client_read: %s\n", ERR_reason_error_string(ERR_get_error()));
 518                         }
 519                 }
 520                 rlen = SSL_read(THREADSSL, &buf[len], bytes - len);
 521                 if (rlen < 1) {
 522                         long errval;
 523
 524                         errval = SSL_get_error(THREADSSL, rlen);
 525                         if (errval == SSL_ERROR_WANT_READ ||
 526                             errval == SSL_ERROR_WANT_WRITE) {
 527                                 sleep(1);
 528                                 continue;
 529                         }
 530                         lprintf(9, "SSL_read got error %ld\n", errval);
 531                         endtls();
 532                         return (client_read_to
 533                                 (WC->http_sock, &buf[len], bytes - len, timeout));
 534                 }
 535                 len += rlen;
 536         }
 537         return (1);
 538 }
 539
 540
 541 #endif                          /* HAVE_OPENSSL */