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