webcit/crypto.c

   1 /*
   2  * $Id$
   3  *
   4  * Provides HTTPS, when the OpenSSL library is available.
   5  */
   6
   7 #ifdef HAVE_OPENSSL
   8
   9 #include "webcit.h"
  10 #include "webserver.h"
  11
  12 #define CTDL_CRYPTO_DIR         "./keys"
  13 #define CTDL_KEY_PATH           CTDL_CRYPTO_DIR "/citadel.key"
  14 #define CTDL_CSR_PATH           CTDL_CRYPTO_DIR "/citadel.csr"
  15 #define CTDL_CER_PATH           CTDL_CRYPTO_DIR "/citadel.cer"
  16 #define SIGN_DAYS               365
  17
  18 SSL_CTX *ssl_ctx;               /* SSL context */
  19 pthread_mutex_t **SSLCritters;  /* Things needing locking */
  20
  21 pthread_key_t ThreadSSL;        /* Per-thread SSL context */
  22
  23 static unsigned long id_callback(void)
  24 {
  25         return (unsigned long) pthread_self();
  26 }
  27
  28
  29 void init_ssl(void)
  30 {
  31         SSL_METHOD *ssl_method;
  32         RSA *rsa=NULL;
  33         X509_REQ *req = NULL;
  34         X509 *cer = NULL;
  35         EVP_PKEY *pk = NULL;
  36         EVP_PKEY *req_pkey = NULL;
  37         X509_NAME *name = NULL;
  38         FILE *fp;
  39         char buf[SIZ];
  40
  41         if (!access("/var/run/egd-pool", F_OK))
  42                 RAND_egd("/var/run/egd-pool");
  43
  44         if (!RAND_status()) {
  45                 lprintf(3,
  46                         "PRNG not adequately seeded, won't do SSL/TLS\n");
  47                 return;
  48         }
  49         SSLCritters =
  50             malloc(CRYPTO_num_locks() * sizeof(pthread_mutex_t *));
  51         if (!SSLCritters) {
  52                 lprintf(1, "citserver: can't allocate memory!!\n");
  53                 /* Nothing's been initialized, just die */
  54                 exit(1);
  55         } else {
  56                 int a;
  57
  58                 for (a = 0; a < CRYPTO_num_locks(); a++) {
  59                         SSLCritters[a] = malloc(sizeof(pthread_mutex_t));
  60                         if (!SSLCritters[a]) {
  61                                 lprintf(1,
  62                                         "citserver: can't allocate memory!!\n");
  63                                 /* Nothing's been initialized, just die */
  64                                 exit(1);
  65                         }
  66                         pthread_mutex_init(SSLCritters[a], NULL);
  67                 }
  68         }
  69
  70         /*
  71          * Initialize SSL transport layer
  72          */
  73         SSL_library_init();
  74         SSL_load_error_strings();
  75         ssl_method = SSLv23_server_method();
  76         if (!(ssl_ctx = SSL_CTX_new(ssl_method))) {
  77                 lprintf(3, "SSL_CTX_new failed: %s\n",
  78                         ERR_reason_error_string(ERR_get_error()));
  79                 return;
  80         }
  81
  82         CRYPTO_set_locking_callback(ssl_lock);
  83         CRYPTO_set_id_callback(id_callback);
  84
  85         /* Get our certificates in order.
  86          * First, create the key/cert directory if it's not there already...
  87          */
  88         mkdir(CTDL_CRYPTO_DIR, 0700);
  89
  90         /*
  91          * Before attempting to generate keys/certificates, first try
  92          * link to them from the Citadel server if it's on the same host.
  93          * We ignore any error return because it either meant that there
  94          * was nothing in Citadel to link from (in which case we just
  95          * generate new files) or the target files already exist (which
  96          * is not fatal either).
  97          */
  98         if (!strcasecmp(ctdlhost, "uds")) {
  99                 sprintf(buf, "%s/keys/citadel.key", ctdlport);
 100                 symlink(buf, CTDL_KEY_PATH);
 101                 sprintf(buf, "%s/keys/citadel.csr", ctdlport);
 102                 symlink(buf, CTDL_CSR_PATH);
 103                 sprintf(buf, "%s/keys/citadel.cer", ctdlport);
 104                 symlink(buf, CTDL_CER_PATH);
 105         }
 106
 107         /*
 108          * If we still don't have a private key, generate one.
 109          */
 110         if (access(CTDL_KEY_PATH, R_OK) != 0) {
 111                 lprintf(5, "Generating RSA key pair.\n");
 112                 rsa = RSA_generate_key(1024,    /* modulus size */
 113                                         65537,  /* exponent */
 114                                         NULL,   /* no callback */
 115                                         NULL);  /* no callback */
 116                 if (rsa == NULL) {
 117                         lprintf(3, "Key generation failed: %s\n",
 118                                 ERR_reason_error_string(ERR_get_error()));
 119                 }
 120                 if (rsa != NULL) {
 121                         fp = fopen(CTDL_KEY_PATH, "w");
 122                         if (fp != NULL) {
 123                                 chmod(CTDL_KEY_PATH, 0600);
 124                                 if (PEM_write_RSAPrivateKey(fp, /* the file */
 125                                                         rsa,    /* the key */
 126                                                         NULL,   /* no enc */
 127                                                         NULL,   /* no passphr */
 128                                                         0,      /* no passphr */
 129                                                         NULL,   /* no callbk */
 130                                                         NULL    /* no callbk */
 131                                 ) != 1) {
 132                                         lprintf(3, "Cannot write key: %s\n",
 133                                                 ERR_reason_error_string(ERR_get_error()));
 134                                         unlink(CTDL_KEY_PATH);
 135                                 }
 136                                 fclose(fp);
 137                         }
 138                         RSA_free(rsa);
 139                 }
 140         }
 141
 142         /*
 143          * Generate a CSR if we don't have one.
 144          */
 145         if (access(CTDL_CSR_PATH, R_OK) != 0) {
 146                 lprintf(5, "Generating a certificate signing request.\n");
 147
 148                 /*
 149                  * Read our key from the file.  No, we don't just keep this
 150                  * in memory from the above key-generation function, because
 151                  * there is the possibility that the key was already on disk
 152                  * and we didn't just generate it now.
 153                  */
 154                 fp = fopen(CTDL_KEY_PATH, "r");
 155                 if (fp) {
 156                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 157                         fclose(fp);
 158                 }
 159
 160                 if (rsa) {
 161
 162                         /* Create a public key from the private key */
 163                         if (pk=EVP_PKEY_new(), pk != NULL) {
 164                                 EVP_PKEY_assign_RSA(pk, rsa);
 165                                 if (req = X509_REQ_new(), req != NULL) {
 166
 167                                         /* Set the public key */
 168                                         X509_REQ_set_pubkey(req, pk);
 169                                         X509_REQ_set_version(req, 0L);
 170
 171                                         name = X509_REQ_get_subject_name(req);
 172
 173                                         /* Tell it who we are */
 174
 175                                         /*
 176                                         X509_NAME_add_entry_by_txt(name, "C",
 177                                                 MBSTRING_ASC, "US", -1, -1, 0);
 178
 179                                         X509_NAME_add_entry_by_txt(name, "ST",
 180                                                 MBSTRING_ASC, "New York", -1, -1, 0);
 181
 182                                         X509_NAME_add_entry_by_txt(name, "L",
 183                                                 MBSTRING_ASC, "Mount Kisco", -1, -1, 0);
 184                                         */
 185
 186                                         X509_NAME_add_entry_by_txt(name, "O",
 187                                                 MBSTRING_ASC, "FIXME.FIXME.org", -1, -1, 0);
 188
 189                                         X509_NAME_add_entry_by_txt(name, "OU",
 190                                                 MBSTRING_ASC, "Citadel server", -1, -1, 0);
 191
 192                                         X509_NAME_add_entry_by_txt(name, "CN",
 193                                                 MBSTRING_ASC, "FIXME.FIXME.org", -1, -1, 0);
 194
 195                                         X509_REQ_set_subject_name(req, name);
 196
 197                                         /* Sign the CSR */
 198                                         if (!X509_REQ_sign(req, pk, EVP_md5())) {
 199                                                 lprintf(3, "X509_REQ_sign(): error\n");
 200                                         }
 201                                         else {
 202                                                 /* Write it to disk. */
 203                                                 fp = fopen(CTDL_CSR_PATH, "w");
 204                                                 if (fp != NULL) {
 205                                                         chmod(CTDL_CSR_PATH, 0600);
 206                                                         PEM_write_X509_REQ(fp, req);
 207                                                         fclose(fp);
 208                                                 }
 209                                         }
 210
 211                                         X509_REQ_free(req);
 212                                 }
 213                         }
 214
 215                         RSA_free(rsa);
 216                 }
 217
 218                 else {
 219                         lprintf(3, "Unable to read private key.\n");
 220                 }
 221         }
 222
 223
 224
 225         /*
 226          * Generate a self-signed certificate if we don't have one.
 227          */
 228         if (access(CTDL_CER_PATH, R_OK) != 0) {
 229                 lprintf(5, "Generating a self-signed certificate.\n");
 230
 231                 /* Same deal as before: always read the key from disk because
 232                  * it may or may not have just been generated.
 233                  */
 234                 fp = fopen(CTDL_KEY_PATH, "r");
 235                 if (fp) {
 236                         rsa = PEM_read_RSAPrivateKey(fp, NULL, NULL, NULL);
 237                         fclose(fp);
 238                 }
 239
 240                 /* This also holds true for the CSR. */
 241                 req = NULL;
 242                 cer = NULL;
 243                 pk = NULL;
 244                 if (rsa) {
 245                         if (pk=EVP_PKEY_new(), pk != NULL) {
 246                                 EVP_PKEY_assign_RSA(pk, rsa);
 247                         }
 248
 249                         fp = fopen(CTDL_CSR_PATH, "r");
 250                         if (fp) {
 251                                 req = PEM_read_X509_REQ(fp, NULL, NULL, NULL);
 252                                 fclose(fp);
 253                         }
 254
 255                         if (req) {
 256                                 if (cer = X509_new(), cer != NULL) {
 257
 258                                         ASN1_INTEGER_set(X509_get_serialNumber(cer), 0);
 259                                         X509_set_issuer_name(cer, req->req_info->subject);
 260                                         X509_set_subject_name(cer, req->req_info->subject);
 261                                         X509_gmtime_adj(X509_get_notBefore(cer), 0);
 262                                         X509_gmtime_adj(X509_get_notAfter(cer),(long)60*60*24*SIGN_DAYS);
 263
 264                                         req_pkey = X509_REQ_get_pubkey(req);
 265                                         X509_set_pubkey(cer, req_pkey);
 266                                         EVP_PKEY_free(req_pkey);
 267
 268                                         /* Sign the cert */
 269                                         if (!X509_sign(cer, pk, EVP_md5())) {
 270                                                 lprintf(3, "X509_sign(): error\n");
 271                                         }
 272                                         else {
 273                                                 /* Write it to disk. */
 274                                                 fp = fopen(CTDL_CER_PATH, "w");
 275                                                 if (fp != NULL) {
 276                                                         chmod(CTDL_CER_PATH, 0600);
 277                                                         PEM_write_X509(fp, cer);
 278                                                         fclose(fp);
 279                                                 }
 280                                         }
 281                                         X509_free(cer);
 282                                 }
 283                         }
 284
 285                         RSA_free(rsa);
 286                 }
 287         }
 288
 289         /*
 290          * Now try to bind to the key and certificate.
 291          * Note that we use SSL_CTX_use_certificate_chain_file() which allows
 292          * the certificate file to contain intermediate certificates.
 293          */
 294         SSL_CTX_use_certificate_chain_file(ssl_ctx, CTDL_CER_PATH);
 295         SSL_CTX_use_PrivateKey_file(ssl_ctx, CTDL_KEY_PATH, SSL_FILETYPE_PEM);
 296         if ( !SSL_CTX_check_private_key(ssl_ctx) ) {
 297                 lprintf(3, "Cannot install certificate: %s\n",
 298                                 ERR_reason_error_string(ERR_get_error()));
 299         }
 300
 301 }
 302
 303
 304 /*
 305  * starttls() starts SSL/TLS encryption for the current session.
 306  */
 307 int starttls(int sock) {
 308         int retval, bits, alg_bits;
 309         SSL *newssl;
 310
 311         pthread_setspecific(ThreadSSL, NULL);
 312
 313         if (!ssl_ctx) {
 314                 return(1);
 315         }
 316         if (!(newssl = SSL_new(ssl_ctx))) {
 317                 lprintf(3, "SSL_new failed: %s\n",
 318                                 ERR_reason_error_string(ERR_get_error()));
 319                 return(2);
 320         }
 321         if (!(SSL_set_fd(newssl, sock))) {
 322                 lprintf(3, "SSL_set_fd failed: %s\n",
 323                         ERR_reason_error_string(ERR_get_error()));
 324                 SSL_free(newssl);
 325                 return(3);
 326         }
 327         retval = SSL_accept(newssl);
 328         if (retval < 1) {
 329                 /*
 330                  * Can't notify the client of an error here; they will
 331                  * discover the problem at the SSL layer and should
 332                  * revert to unencrypted communications.
 333                  */
 334                 long errval;
 335
 336                 errval = SSL_get_error(newssl, retval);
 337                 lprintf(3, "SSL_accept failed: %s\n",
 338                         ERR_reason_error_string(ERR_get_error()));
 339                 SSL_free(newssl);
 340                 newssl = NULL;
 341                 return(4);
 342         }
 343         BIO_set_close(newssl->rbio, BIO_NOCLOSE);
 344         bits =
 345             SSL_CIPHER_get_bits(SSL_get_current_cipher(newssl),
 346                                 &alg_bits);
 347         lprintf(5, "SSL/TLS using %s on %s (%d of %d bits)\n",
 348                 SSL_CIPHER_get_name(SSL_get_current_cipher(newssl)),
 349                 SSL_CIPHER_get_version(SSL_get_current_cipher(newssl)),
 350                 bits, alg_bits);
 351
 352         pthread_setspecific(ThreadSSL, newssl);
 353         return(0);
 354 }
 355
 356
 357
 358 /*
 359  * endtls() shuts down the TLS connection
 360  *
 361  * WARNING:  This may make your session vulnerable to a known plaintext
 362  * attack in the current implmentation.
 363  */
 364 void endtls(void)
 365 {
 366         lprintf(5, "Ending SSL/TLS\n");
 367         SSL_shutdown(THREADSSL);
 368         SSL_free(THREADSSL);
 369         pthread_setspecific(ThreadSSL, NULL);
 370 }
 371
 372
 373 /*
 374  * ssl_lock() callback for OpenSSL mutex locks
 375  */
 376 void ssl_lock(int mode, int n, const char *file, int line)
 377 {
 378         if (mode & CRYPTO_LOCK)
 379                 pthread_mutex_lock(SSLCritters[n]);
 380         else
 381                 pthread_mutex_unlock(SSLCritters[n]);
 382 }
 383
 384 /*
 385  * client_write_ssl() Send binary data to the client encrypted.
 386  */
 387 void client_write_ssl(char *buf, int nbytes)
 388 {
 389         int retval;
 390         int nremain;
 391         char junk[1];
 392
 393         nremain = nbytes;
 394
 395         while (nremain > 0) {
 396                 if (SSL_want_write(THREADSSL)) {
 397                         if ((SSL_read(THREADSSL, junk, 0)) < 1) {
 398                                 lprintf(9, "SSL_read in client_write: %s\n", ERR_reason_error_string(ERR_get_error()));
 399                         }
 400                 }
 401                 retval =
 402                     SSL_write(THREADSSL, &buf[nbytes - nremain], nremain);
 403                 if (retval < 1) {
 404                         long errval;
 405
 406                         errval = SSL_get_error(THREADSSL, retval);
 407                         if (errval == SSL_ERROR_WANT_READ ||
 408                             errval == SSL_ERROR_WANT_WRITE) {
 409                                 sleep(1);
 410                                 continue;
 411                         }
 412                         lprintf(9, "SSL_write got error %ld, ret %d\n", errval, retval);
 413                         if (retval == -1)
 414                                 lprintf(9, "errno is %d\n", errno);
 415                         endtls();
 416                         return;
 417                 }
 418                 nremain -= retval;
 419         }
 420 }
 421
 422
 423 /*
 424  * client_read_ssl() - read data from the encrypted layer.
 425  */
 426 int client_read_ssl(char *buf, int bytes, int timeout)
 427 {
 428 #if 0
 429         fd_set rfds;
 430         struct timeval tv;
 431         int retval;
 432         int s;
 433 #endif
 434         int len, rlen;
 435         char junk[1];
 436
 437         len = 0;
 438         while (len < bytes) {
 439 #if 0
 440                 /*
 441                  * This code is disabled because we don't need it when
 442                  * using blocking reads (which we are). -IO
 443                  */
 444                 FD_ZERO(&rfds);
 445                 s = BIO_get_fd(THREADSSL->rbio, NULL);
 446                 FD_SET(s, &rfds);
 447                 tv.tv_sec = timeout;
 448                 tv.tv_usec = 0;
 449
 450                 retval = select(s + 1, &rfds, NULL, NULL, &tv);
 451
 452                 if (FD_ISSET(s, &rfds) == 0) {
 453                         return (0);
 454                 }
 455
 456 #endif
 457                 if (SSL_want_read(THREADSSL)) {
 458                         if ((SSL_write(THREADSSL, junk, 0)) < 1) {
 459                                 lprintf(9, "SSL_write in client_read: %s\n", ERR_reason_error_string(ERR_get_error()));
 460                         }
 461                 }
 462                 rlen = SSL_read(THREADSSL, &buf[len], bytes - len);
 463                 if (rlen < 1) {
 464                         long errval;
 465
 466                         errval = SSL_get_error(THREADSSL, rlen);
 467                         if (errval == SSL_ERROR_WANT_READ ||
 468                             errval == SSL_ERROR_WANT_WRITE) {
 469                                 sleep(1);
 470                                 continue;
 471                         }
 472                         lprintf(9, "SSL_read got error %ld\n", errval);
 473                         endtls();
 474                         return (0);
 475                 }
 476                 len += rlen;
 477         }
 478         return (1);
 479 }
 480
 481
 482 #endif                          /* HAVE_OPENSSL */