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         char buf[SIZ];
  52
  53         if (!access("/var/run/egd-pool", F_OK))
  54                 RAND_egd("/var/run/egd-pool");
  55
  56         if (!RAND_status()) {
  57                 lprintf(3,
  58                         "PRNG not adequately seeded, won't do SSL/TLS\n");
  59                 return;
  60         }
  61         SSLCritters =
  62             malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  63         if (!SSLCritters) {
  64                 lprintf(1, "citserver: can't allocate memory!!\n");
  65                 /* Nothing's been initialized, just die */
  66                 exit(1);
  67         } else {
  68                 int a;
  69
  70                 for (a = 0; a < CRYPTO_num_locks(); a++) {
  71                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
  72                         if (!SSLCritters[a]) {
  73                                 lprintf(1,
  74                                         "citserver: can't allocate memory!!\n");
  75                                 /* Nothing's been initialized, just die */
  76                                 exit(1);
  77                         }
  78                         pthread_mutex_init(SSLCritters[a], NULL);
  79                 }
  80         }
  81
  82         /*
  83          * Initialize SSL transport layer
  84          */
  85         SSL_library_init();
  86         OpenSSL_add_all_algorithms();
  87         SSL_load_error_strings();
  88         ssl_method = SSLv2_server_method();
  89         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
  90                 lprintf(3, "SSL_CTX_new failed: %s\n",
  91                         ERR_reason_error_string(ERR_get_error()));
  92                 return;
  93         }
  94
  95         CRYPTO_set_locking_callback(ssl_lock);
  96         CRYPTO_set_id_callback(id_callback);
  97
  98         /* Load DH parameters into the context */
  99         dh = DH_new();
 100         if (!dh) {
 101                 lprintf(3, "init_ssl() can't allocate a DH object: %s\n",
 102                         ERR_reason_error_string(ERR_get_error()));
 103                 SSL_CTX_free(ssl_ctx);
 104                 ssl_ctx = NULL;
 105                 return;
 106         }
 107         if (!(BN_hex2bn(&(dh->p), DH_P))) {
 108                 lprintf(3, "init_ssl() can't assign DH_P: %s\n",
 109                         ERR_reason_error_string(ERR_get_error()));
 110                 SSL_CTX_free(ssl_ctx);
 111                 ssl_ctx = NULL;
 112                 return;
 113         }
 114         if (!(BN_hex2bn(&(dh->g), DH_G))) {
 115                 lprintf(3, "init_ssl() can't assign DH_G: %s\n",
 116                         ERR_reason_error_string(ERR_get_error()));
 117                 SSL_CTX_free(ssl_ctx);
 118                 ssl_ctx = NULL;
 119                 return;
 120         }
 121         dh->length = DH_L;
 122         SSL_CTX_set_tmp_dh(ssl_ctx, dh);
 123         DH_free(dh);
 124
 125         /* Get our certificates in order.
 126          * First, create the key/cert directory if it's not there already...
 127          */
 128         mkdir(CTDL_CRYPTO_DIR, 0700);
 129
 130         /*
 131          * Before attempting to generate keys/certificates, first try
 132          * link to them from the Citadel server if it's on the same host.
 133          * We ignore any error return because it either meant that there
 134          * was nothing in Citadel to link from (in which case we just
 135          * generate new files) or the target files already exist (which
 136          * is not fatal either).
 137          */
 138         if (!strcasecmp(ctdlhost, "uds")) {
 139                 sprintf(buf, "%s/keys/citadel.key", ctdlport);
 140                 symlink(buf, CTDL_KEY_PATH);
 141                 sprintf(buf, "%s/keys/citadel.csr", ctdlport);
 142                 symlink(buf, CTDL_CSR_PATH);
 143                 sprintf(buf, "%s/keys/citadel.cer", ctdlport);
 144                 symlink(buf, CTDL_CER_PATH);
 145         }
 146
 147         /*
 148          * If we still don't have a private key, generate one.
 149          */
 150         if (access(CTDL_KEY_PATH, R_OK) != 0) {
 151                 lprintf(5, "Generating RSA key pair.\n");
 152                 rsa = RSA_generate_key(1024,    /* modulus size */
 153                                         65537,  /* exponent */
 154                                         NULL,   /* no callback */
 155                                         NULL);  /* no callback */
 156                 if (rsa == NULL) {
 157                         lprintf(3, "Key generation failed: %s\n",
 158                                 ERR_reason_error_string(ERR_get_error()));
 159                 }
 160                 if (rsa != NULL) {
 161                         fp = fopen(CTDL_KEY_PATH, "w");
 162                         if (fp != NULL) {
 163                                 chmod(CTDL_KEY_PATH, 0600);
 164                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 165                                                         rsa,    /* the key */
 166                                                         NULL,   /* no enc */
 167                                                         NULL,   /* no passphr */
 168                                                         0,      /* no passphr */
 169                                                         NULL,   /* no callbk */
 170                                                         NULL    /* no callbk */
 171                                 ) != 1) {
 172                                         lprintf(3, "Cannot write key: %s\n",
 173                                                 ERR_reason_error_string(ERR_get_error()));
 174                                         unlink(CTDL_KEY_PATH);
 175                                 }
 176                                 fclose(fp);
 177                         }
 178                         RSA_free(rsa);
 179                 }
 180         }
 181
 182         /*
 183          * Generate a CSR if we don't have one.
 184          */
 185         if (access(CTDL_CSR_PATH, R_OK) != 0) {
 186                 lprintf(5, "Generating a certificate signing request.\n");
 187
 188                 /*
 189                  * Read our key from the file.  No, we don't just keep this
 190                  * in memory from the above key-generation function, because
 191                  * there is the possibility that the key was already on disk
 192                  * and we didn't just generate it now.
 193                  */
 194                 fp = fopen(CTDL_KEY_PATH, "r");
 195                 if (fp) {
 196                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 197                         fclose(fp);
 198                 }
 199
 200                 if (rsa) {
 201
 202                         /* Create a public key from the private key */
 203                         if (pk=EVP_PKEY_new(), pk != NULL) {
 204                                 EVP_PKEY_assign_RSA(pk, rsa);
 205                                 if (req = X509_REQ_new(), req != NULL) {
 206
 207                                         /* Set the public key */
 208                                         X509_REQ_set_pubkey(req, pk);
 209                                         X509_REQ_set_version(req, 0L);
 210
 211                                         name = X509_REQ_get_subject_name(req);
 212
 213                                         /* Tell it who we are */
 214
 215                                         /*
 216                                         X509_NAME_add_entry_by_txt(name, "C",
 217                                                 MBSTRING_ASC, "US", -1, -1, 0);
 218
 219                                         X509_NAME_add_entry_by_txt(name, "ST",
 220                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 221
 222                                         X509_NAME_add_entry_by_txt(name, "L",
 223                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 224                                         */
 225
 226                                         X509_NAME_add_entry_by_txt(name, "O",
 227                                                 MBSTRING_ASC, "FIXME.FIXME.org", -1, -1, 0);
 228
 229                                         X509_NAME_add_entry_by_txt(name, "OU",
 230                                                 MBSTRING_ASC, "Citadel server", -1, -1, 0);
 231
 232                                         X509_NAME_add_entry_by_txt(name, "CN",
 233                                                 MBSTRING_ASC, "FIXME.FIXME.org", -1, -1, 0);
 234
 235                                         X509_REQ_set_subject_name(req, name);
 236
 237                                         /* Sign the CSR */
 238                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 239                                                 lprintf(3, "X509_REQ_sign(): error\n");
 240                                         }
 241                                         else {
 242                                                 /* Write it to disk. */
 243                                                 fp = fopen(CTDL_CSR_PATH, "w");
 244                                                 if (fp != NULL) {
 245                                                         chmod(CTDL_CSR_PATH, 0600);
 246                                                         PEM_write_X509_REQ(fp, req);
 247                                                         fclose(fp);
 248                                                 }
 249                                         }
 250
 251                                         X509_REQ_free(req);
 252                                 }
 253                         }
 254
 255                         RSA_free(rsa);
 256                 }
 257
 258                 else {
 259                         lprintf(3, "Unable to read private key.\n");
 260                 }
 261         }
 262
 263
 264
 265         /*
 266          * Generate a self-signed certificate if we don't have one.
 267          */
 268         if (access(CTDL_CER_PATH, R_OK) != 0) {
 269                 lprintf(5, "Generating a self-signed certificate.\n");
 270
 271                 /* Same deal as before: always read the key from disk because
 272                  * it may or may not have just been generated.
 273                  */
 274                 fp = fopen(CTDL_KEY_PATH, "r");
 275                 if (fp) {
 276                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 277                         fclose(fp);
 278                 }
 279
 280                 /* This also holds true for the CSR. */
 281                 req = NULL;
 282                 cer = NULL;
 283                 pk = NULL;
 284                 if (rsa) {
 285                         if (pk=EVP_PKEY_new(), pk != NULL) {
 286                                 EVP_PKEY_assign_RSA(pk, rsa);
 287                         }
 288
 289                         fp = fopen(CTDL_CSR_PATH, "r");
 290                         if (fp) {
 291                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 292                                 fclose(fp);
 293                         }
 294
 295                         if (req) {
 296                                 if (cer = X509_new(), cer != NULL) {
 297
 298                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 299                                         X509_set_issuer_name(cer, req->req_info->subject);
 300                                         X509_set_subject_name(cer, req->req_info->subject);
 301                                         X509_gmtime_adj(X509_get_notBefore(cer), 0);
 302                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 303
 304                                         req_pkey = X509_REQ_get_pubkey(req);
 305                                         X509_set_pubkey(cer, req_pkey);
 306                                         EVP_PKEY_free(req_pkey);
 307
 308                                         /* Sign the cert */
 309                                         if (!X509_sign(cer, pk, EVP_md5())) {
 310                                                 lprintf(3, "X509_sign(): error\n");
 311                                         }
 312                                         else {
 313                                                 /* Write it to disk. */
 314                                                 fp = fopen(CTDL_CER_PATH, "w");
 315                                                 if (fp != NULL) {
 316                                                         chmod(CTDL_CER_PATH, 0600);
 317                                                         PEM_write_X509(fp, cer);
 318                                                         fclose(fp);
 319                                                 }
 320                                         }
 321                                         X509_free(cer);
 322                                 }
 323                         }
 324
 325                         RSA_free(rsa);
 326                 }
 327         }
 328
 329
 330         /*
 331          * Now try to bind to the key and certificate.
 332          */
 333         SSL_CTX_use_certificate_file(ssl_ctx, CTDL_CER_PATH, SSL_FILETYPE_PEM);
 334         SSL_CTX_use_PrivateKey_file(ssl_ctx, CTDL_KEY_PATH, SSL_FILETYPE_PEM);
 335         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 336                 lprintf(3, "Cannot install certificate: %s\n",
 337                                 ERR_reason_error_string(ERR_get_error()));
 338         }
 339
 340 }
 341
 342
 343 /*
 344  * starttls() starts SSL/TLS encryption for the current session.
 345  */
 346 int starttls(int sock) {
 347         int retval, bits, alg_bits;
 348         SSL *newssl;
 349
 350         pthread_setspecific(ThreadSSL, NULL);
 351
 352         if (!ssl_ctx) {
 353                 return(1);
 354         }
 355         if (!(newssl = SSL_new(ssl_ctx))) {
 356                 lprintf(3, "SSL_new failed: %s\n",
 357                                 ERR_reason_error_string(ERR_get_error()));
 358                 return(2);
 359         }
 360         if (!(SSL_set_fd(newssl, sock))) {
 361                 lprintf(3, "SSL_set_fd failed: %s\n",
 362                         ERR_reason_error_string(ERR_get_error()));
 363                 SSL_free(newssl);
 364                 return(3);
 365         }
 366         retval = SSL_accept(newssl);
 367         if (retval < 1) {
 368                 /*
 369                  * Can't notify the client of an error here; they will
 370                  * discover the problem at the SSL layer and should
 371                  * revert to unencrypted communications.
 372                  */
 373                 long errval;
 374
 375                 errval = SSL_get_error(newssl, retval);
 376                 lprintf(3, "SSL_accept failed: %s\n",
 377                         ERR_reason_error_string(ERR_get_error()));
 378                 SSL_free(newssl);
 379                 newssl = NULL;
 380                 return(4);
 381         }
 382         BIO_set_close(newssl->rbio, BIO_NOCLOSE);
 383         bits =
 384             SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl),
 385                                 &alg_bits);
 386         lprintf(5, "SSL/TLS using %s on %s (%d of %d bits)\n",
 387                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 388                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 389                 bits, alg_bits);
 390
 391         pthread_setspecific(ThreadSSL, newssl);
 392         return(0);
 393 }
 394
 395
 396
 397 /*
 398  * endtls() shuts down the TLS connection
 399  *
 400  * WARNING:  This may make your session vulnerable to a known plaintext
 401  * attack in the current implmentation.
 402  */
 403 void endtls(void)
 404 {
 405         lprintf(5, "Ending SSL/TLS\n");
 406         SSL_shutdown(THREADSSL);
 407         SSL_free(THREADSSL);
 408         pthread_setspecific(ThreadSSL, NULL);
 409 }
 410
 411
 412 /*
 413  * ssl_lock() callback for OpenSSL mutex locks
 414  */
 415 void ssl_lock(int mode, int n, const char *file, int line)
 416 {
 417         if (mode & CRYPTO_LOCK)
 418                 pthread_mutex_lock(SSLCritters[n]);
 419         else
 420                 pthread_mutex_unlock(SSLCritters[n]);
 421 }
 422
 423 /*
 424  * client_write_ssl() Send binary data to the client encrypted.
 425  */
 426 void client_write_ssl(char *buf, int nbytes)
 427 {
 428         int retval;
 429         int nremain;
 430         char junk[1];
 431
 432         nremain = nbytes;
 433
 434         while (nremain > 0) {
 435                 if (SSL_want_write(THREADSSL)) {
 436                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 437                                 lprintf(9, "SSL_read in client_write: %s\n", ERR_reason_error_string(ERR_get_error()));
 438                         }
 439                 }
 440                 retval =
 441                     SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 442                 if (retval < 1) {
 443                         long errval;
 444
 445                         errval = SSL_get_error(THREADSSL, retval);
 446                         if (errval == SSL_ERROR_WANT_READ ||
 447                             errval == SSL_ERROR_WANT_WRITE) {
 448                                 sleep(1);
 449                                 continue;
 450                         }
 451                         lprintf(9, "SSL_write got error %ld, ret %d\n", errval, retval);
 452                         if (retval == -1)
 453                                 lprintf(9, "errno is %d\n", errno);
 454                         endtls();
 455                         return;
 456                 }
 457                 nremain -= retval;
 458         }
 459 }
 460
 461
 462 /*
 463  * client_read_ssl() - read data from the encrypted layer.
 464  */
 465 int client_read_ssl(char *buf, int bytes, int timeout)
 466 {
 467 #if 0
 468         fd_set rfds;
 469         struct timeval tv;
 470         int retval;
 471         int s;
 472 #endif
 473         int len, rlen;
 474         char junk[1];
 475
 476         len = 0;
 477         while (len < bytes) {
 478 #if 0
 479                 /*
 480                  * This code is disabled because we don't need it when
 481                  * using blocking reads (which we are). -IO
 482                  */
 483                 FD_ZERO(&rfds);
 484                 s = BIO_get_fd(THREADSSL->rbio, NULL);
 485                 FD_SET(s, &rfds);
 486                 tv.tv_sec = timeout;
 487                 tv.tv_usec = 0;
 488
 489                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 490
 491                 if (FD_ISSET(s, &rfds) == 0) {
 492                         return (0);
 493                 }
 494
 495 #endif
 496                 if (SSL_want_read(THREADSSL)) {
 497                         if ((SSL_write(THREADSSL, junk, 0)) < 1) {
 498                                 lprintf(9, "SSL_write in client_read: %s\n", ERR_reason_error_string(ERR_get_error()));
 499                         }
 500                 }
 501                 rlen = SSL_read(THREADSSL, &buf[len], bytes - len);
 502                 if (rlen < 1) {
 503                         long errval;
 504
 505                         errval = SSL_get_error(THREADSSL, rlen);
 506                         if (errval == SSL_ERROR_WANT_READ ||
 507                             errval == SSL_ERROR_WANT_WRITE) {
 508                                 sleep(1);
 509                                 continue;
 510                         }
 511                         lprintf(9, "SSL_read got error %ld\n", errval);
 512                         endtls();
 513                         return (0);
 514                 }
 515                 len += rlen;
 516         }
 517         return (1);
 518 }
 519
 520
 521 #endif                          /* HAVE_OPENSSL */