source4/lib/tls/tls.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    transport layer security handling code
   5
   6    Copyright (C) Andrew Tridgell 2004-2005
   7    Copyright (C) Stefan Metzmacher 2004
   8    Copyright (C) Andrew Bartlett 2006
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  22 */
  23
  24 #include "includes.h"
  25 #include "system/filesys.h"
  26 #include "lib/events/events.h"
  27 #include "lib/socket/socket.h"
  28 #include "lib/tls/tls.h"
  29 #include "param/param.h"
  30
  31 #if ENABLE_GNUTLS
  32 #include <gnutls/gnutls.h>
  33
  34 #define DH_BITS 1024
  35
  36 #if defined(HAVE_GNUTLS_DATUM) && !defined(HAVE_GNUTLS_DATUM_T)
  37 typedef gnutls_datum gnutls_datum_t;
  38 #endif
  39
  40 /* hold persistent tls data */
  41 struct tls_params {
  42         gnutls_certificate_credentials x509_cred;
  43         gnutls_dh_params dh_params;
  44         bool tls_enabled;
  45         const char *tls_priority;
  46 };
  47 #endif
  48
  49 /* hold per connection tls data */
  50 struct tls_context {
  51         struct socket_context *socket;
  52         struct tevent_fd *fde;
  53         bool tls_enabled;
  54 #if ENABLE_GNUTLS
  55         gnutls_session session;
  56         bool done_handshake;
  57         bool have_first_byte;
  58         uint8_t first_byte;
  59         bool tls_detect;
  60         const char *plain_chars;
  61         bool output_pending;
  62         gnutls_certificate_credentials xcred;
  63         bool interrupted;
  64 #endif
  65 };
  66
  67 bool tls_enabled(struct socket_context *sock)
  68 {
  69         struct tls_context *tls;
  70         if (!sock) {
  71                 return false;
  72         }
  73         if (strcmp(sock->backend_name, "tls") != 0) {
  74                 return false;
  75         }
  76         tls = talloc_get_type(sock->private_data, struct tls_context);
  77         if (!tls) {
  78                 return false;
  79         }
  80         return tls->tls_enabled;
  81 }
  82
  83
  84 #if ENABLE_GNUTLS
  85
  86 static const struct socket_ops tls_socket_ops;
  87
  88 static NTSTATUS tls_socket_init(struct socket_context *sock)
  89 {
  90         switch (sock->type) {
  91         case SOCKET_TYPE_STREAM:
  92                 break;
  93         default:
  94                 return NT_STATUS_INVALID_PARAMETER;
  95         }
  96
  97         sock->backend_name = "tls";
  98
  99         return NT_STATUS_OK;
 100 }
 101
 102 #define TLSCHECK(call) do { \
 103         ret = call; \
 104         if (ret < 0) { \
 105                 DEBUG(0,("TLS %s - %s\n", #call, gnutls_strerror(ret))); \
 106                 goto failed; \
 107         } \
 108 } while (0)
 109
 110
 111 /*
 112   callback for reading from a socket
 113 */
 114 static ssize_t tls_pull(gnutls_transport_ptr ptr, void *buf, size_t size)
 115 {
 116         struct tls_context *tls = talloc_get_type(ptr, struct tls_context);
 117         NTSTATUS status;
 118         size_t nread;
 119
 120         if (tls->have_first_byte) {
 121                 *(uint8_t *)buf = tls->first_byte;
 122                 tls->have_first_byte = false;
 123                 return 1;
 124         }
 125
 126         status = socket_recv(tls->socket, buf, size, &nread);
 127         if (NT_STATUS_EQUAL(status, NT_STATUS_END_OF_FILE)) {
 128                 return 0;
 129         }
 130         if (NT_STATUS_IS_ERR(status)) {
 131                 TEVENT_FD_NOT_READABLE(tls->fde);
 132                 TEVENT_FD_NOT_WRITEABLE(tls->fde);
 133                 errno = EBADF;
 134                 return -1;
 135         }
 136         if (!NT_STATUS_IS_OK(status)) {
 137                 TEVENT_FD_READABLE(tls->fde);
 138                 errno = EAGAIN;
 139                 return -1;
 140         }
 141         if (tls->output_pending) {
 142                 TEVENT_FD_WRITEABLE(tls->fde);
 143         }
 144         if (size != nread) {
 145                 TEVENT_FD_READABLE(tls->fde);
 146         }
 147         return nread;
 148 }
 149
 150 /*
 151   callback for writing to a socket
 152 */
 153 static ssize_t tls_push(gnutls_transport_ptr ptr, const void *buf, size_t size)
 154 {
 155         struct tls_context *tls = talloc_get_type(ptr, struct tls_context);
 156         NTSTATUS status;
 157         size_t nwritten, total_nwritten = 0;
 158         DATA_BLOB b;
 159
 160         if (!tls->tls_enabled) {
 161                 return size;
 162         }
 163
 164         b.data = discard_const(buf);
 165         b.length = size;
 166
 167         /* Cope with socket_wrapper 1500 byte chunking for PCAP */
 168         do {
 169                 status = socket_send(tls->socket, &b, &nwritten);
 170
 171                 if (NT_STATUS_EQUAL(status, STATUS_MORE_ENTRIES)) {
 172                         errno = EAGAIN;
 173                         return -1;
 174                 }
 175                 if (!NT_STATUS_IS_OK(status)) {
 176                         TEVENT_FD_WRITEABLE(tls->fde);
 177                         return -1;
 178                 }
 179
 180                 total_nwritten += nwritten;
 181
 182                 if (size == nwritten) {
 183                         break;
 184                 }
 185
 186                 b.data += nwritten;
 187                 b.length -= nwritten;
 188
 189                 TEVENT_FD_WRITEABLE(tls->fde);
 190         } while (b.length);
 191
 192         return total_nwritten;
 193 }
 194
 195 /*
 196   destroy a tls session
 197  */
 198 static int tls_destructor(struct tls_context *tls)
 199 {
 200         int ret;
 201         ret = gnutls_bye(tls->session, GNUTLS_SHUT_WR);
 202         if (ret < 0) {
 203                 DEBUG(4,("TLS gnutls_bye failed - %s\n", gnutls_strerror(ret)));
 204         }
 205         return 0;
 206 }
 207
 208
 209 /*
 210   possibly continue the handshake process
 211 */
 212 static NTSTATUS tls_handshake(struct tls_context *tls)
 213 {
 214         int ret;
 215
 216         if (tls->done_handshake) {
 217                 return NT_STATUS_OK;
 218         }
 219
 220         ret = gnutls_handshake(tls->session);
 221         if (ret == GNUTLS_E_INTERRUPTED || ret == GNUTLS_E_AGAIN) {
 222                 if (gnutls_record_get_direction(tls->session) == 1) {
 223                         TEVENT_FD_WRITEABLE(tls->fde);
 224                 }
 225                 return STATUS_MORE_ENTRIES;
 226         }
 227         if (ret < 0) {
 228                 DEBUG(0,("TLS gnutls_handshake failed - %s\n", gnutls_strerror(ret)));
 229                 return NT_STATUS_UNEXPECTED_NETWORK_ERROR;
 230         }
 231         tls->done_handshake = true;
 232         return NT_STATUS_OK;
 233 }
 234
 235 /*
 236   possibly continue an interrupted operation
 237 */
 238 static NTSTATUS tls_interrupted(struct tls_context *tls)
 239 {
 240         int ret;
 241
 242         if (!tls->interrupted) {
 243                 return NT_STATUS_OK;
 244         }
 245         if (gnutls_record_get_direction(tls->session) == 1) {
 246                 ret = gnutls_record_send(tls->session, NULL, 0);
 247         } else {
 248                 ret = gnutls_record_recv(tls->session, NULL, 0);
 249         }
 250         if (ret == GNUTLS_E_INTERRUPTED || ret == GNUTLS_E_AGAIN) {
 251                 return STATUS_MORE_ENTRIES;
 252         }
 253         tls->interrupted = false;
 254         return NT_STATUS_OK;
 255 }
 256
 257 /*
 258   see how many bytes are pending on the connection
 259 */
 260 static NTSTATUS tls_socket_pending(struct socket_context *sock, size_t *npending)
 261 {
 262         struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
 263         if (!tls->tls_enabled || tls->tls_detect) {
 264                 return socket_pending(tls->socket, npending);
 265         }
 266         *npending = gnutls_record_check_pending(tls->session);
 267         if (*npending == 0) {
 268                 NTSTATUS status = socket_pending(tls->socket, npending);
 269                 if (*npending == 0) {
 270                         /* seems to be a gnutls bug */
 271                         (*npending) = 100;
 272                 }
 273                 return status;
 274         }
 275         return NT_STATUS_OK;
 276 }
 277
 278 /*
 279   receive data either by tls or normal socket_recv
 280 */
 281 static NTSTATUS tls_socket_recv(struct socket_context *sock, void *buf,
 282                                 size_t wantlen, size_t *nread)
 283 {
 284         int ret;
 285         NTSTATUS status;
 286         struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
 287
 288         if (tls->tls_enabled && tls->tls_detect) {
 289                 status = socket_recv(tls->socket, &tls->first_byte, 1, nread);
 290                 NT_STATUS_NOT_OK_RETURN(status);
 291                 if (*nread == 0) return NT_STATUS_OK;
 292                 tls->tls_detect = false;
 293                 /* look for the first byte of a valid HTTP operation */
 294                 if (strchr(tls->plain_chars, tls->first_byte)) {
 295                         /* not a tls link */
 296                         tls->tls_enabled = false;
 297                         *(uint8_t *)buf = tls->first_byte;
 298                         return NT_STATUS_OK;
 299                 }
 300                 tls->have_first_byte = true;
 301         }
 302
 303         if (!tls->tls_enabled) {
 304                 return socket_recv(tls->socket, buf, wantlen, nread);
 305         }
 306
 307         status = tls_handshake(tls);
 308         NT_STATUS_NOT_OK_RETURN(status);
 309
 310         status = tls_interrupted(tls);
 311         NT_STATUS_NOT_OK_RETURN(status);
 312
 313         ret = gnutls_record_recv(tls->session, buf, wantlen);
 314         if (ret == GNUTLS_E_INTERRUPTED || ret == GNUTLS_E_AGAIN) {
 315                 if (gnutls_record_get_direction(tls->session) == 1) {
 316                         TEVENT_FD_WRITEABLE(tls->fde);
 317                 }
 318                 tls->interrupted = true;
 319                 return STATUS_MORE_ENTRIES;
 320         }
 321         if (ret < 0) {
 322                 return NT_STATUS_UNEXPECTED_NETWORK_ERROR;
 323         }
 324         *nread = ret;
 325         return NT_STATUS_OK;
 326 }
 327
 328
 329 /*
 330   send data either by tls or normal socket_recv
 331 */
 332 static NTSTATUS tls_socket_send(struct socket_context *sock,
 333                                 const DATA_BLOB *blob, size_t *sendlen)
 334 {
 335         NTSTATUS status;
 336         int ret;
 337         struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
 338
 339         if (!tls->tls_enabled) {
 340                 return socket_send(tls->socket, blob, sendlen);
 341         }
 342
 343         status = tls_handshake(tls);
 344         NT_STATUS_NOT_OK_RETURN(status);
 345
 346         status = tls_interrupted(tls);
 347         NT_STATUS_NOT_OK_RETURN(status);
 348
 349         ret = gnutls_record_send(tls->session, blob->data, blob->length);
 350         if (ret == GNUTLS_E_INTERRUPTED || ret == GNUTLS_E_AGAIN) {
 351                 if (gnutls_record_get_direction(tls->session) == 1) {
 352                         TEVENT_FD_WRITEABLE(tls->fde);
 353                 }
 354                 tls->interrupted = true;
 355                 return STATUS_MORE_ENTRIES;
 356         }
 357         if (ret < 0) {
 358                 DEBUG(0,("gnutls_record_send of %d failed - %s\n", (int)blob->length, gnutls_strerror(ret)));
 359                 return NT_STATUS_UNEXPECTED_NETWORK_ERROR;
 360         }
 361         *sendlen = ret;
 362         tls->output_pending = (ret < blob->length);
 363         return NT_STATUS_OK;
 364 }
 365
 366
 367 /*
 368   initialise global tls state
 369 */
 370 struct tls_params *tls_initialise(TALLOC_CTX *mem_ctx, struct loadparm_context *lp_ctx)
 371 {
 372         struct tls_params *params;
 373         int ret;
 374         struct stat st;
 375         TALLOC_CTX *tmp_ctx = talloc_new(mem_ctx);
 376         const char *keyfile = lpcfg_tls_keyfile(tmp_ctx, lp_ctx);
 377         const char *certfile = lpcfg_tls_certfile(tmp_ctx, lp_ctx);
 378         const char *cafile = lpcfg_tls_cafile(tmp_ctx, lp_ctx);
 379         const char *crlfile = lpcfg_tls_crlfile(tmp_ctx, lp_ctx);
 380         const char *dhpfile = lpcfg_tls_dhpfile(tmp_ctx, lp_ctx);
 381         void tls_cert_generate(TALLOC_CTX *, const char *, const char *, const char *, const char *);
 382         params = talloc(mem_ctx, struct tls_params);
 383         if (params == NULL) {
 384                 talloc_free(tmp_ctx);
 385                 return NULL;
 386         }
 387
 388         if (!lpcfg_tls_enabled(lp_ctx) || keyfile == NULL || *keyfile == 0) {
 389                 params->tls_enabled = false;
 390                 talloc_free(tmp_ctx);
 391                 return params;
 392         }
 393
 394         params->tls_priority = lpcfg_tls_priority(lp_ctx);
 395
 396         if (!file_exist(cafile)) {
 397                 char *hostname = talloc_asprintf(mem_ctx, "%s.%s",
 398                                                  lpcfg_netbios_name(lp_ctx),
 399                                                  lpcfg_dnsdomain(lp_ctx));
 400                 if (hostname == NULL) {
 401                         ret = GNUTLS_E_MEMORY_ERROR;
 402                         goto init_failed;
 403                 }
 404                 tls_cert_generate(params, hostname, keyfile, certfile, cafile);
 405                 talloc_free(hostname);
 406         }
 407
 408         if (file_exist(keyfile) &&
 409             !file_check_permissions(keyfile, geteuid(), 0600, &st))
 410         {
 411                 DEBUG(0, ("Invalid permissions on TLS private key file '%s':\n"
 412                           "owner uid %u should be %u, mode 0%o should be 0%o\n"
 413                           "This is known as CVE-2013-4476.\n"
 414                           "Removing all tls .pem files will cause an "
 415                           "auto-regeneration with the correct permissions.\n",
 416                           keyfile,
 417                           (unsigned int)st.st_uid, geteuid(),
 418                           (unsigned int)(st.st_mode & 0777), 0600));
 419                 talloc_free(tmp_ctx);
 420                 return NULL;
 421         }
 422
 423         ret = gnutls_global_init();
 424         if (ret < 0) goto init_failed;
 425
 426         gnutls_certificate_allocate_credentials(&params->x509_cred);
 427         if (ret < 0) goto init_failed;
 428
 429         if (cafile && *cafile) {
 430                 ret = gnutls_certificate_set_x509_trust_file(params->x509_cred, cafile,
 431                                                              GNUTLS_X509_FMT_PEM);
 432                 if (ret < 0) {
 433                         DEBUG(0,("TLS failed to initialise cafile %s\n", cafile));
 434                         goto init_failed;
 435                 }
 436         }
 437
 438         if (crlfile && *crlfile) {
 439                 ret = gnutls_certificate_set_x509_crl_file(params->x509_cred,
 440                                                            crlfile,
 441                                                            GNUTLS_X509_FMT_PEM);
 442                 if (ret < 0) {
 443                         DEBUG(0,("TLS failed to initialise crlfile %s\n", crlfile));
 444                         goto init_failed;
 445                 }
 446         }
 447
 448         ret = gnutls_certificate_set_x509_key_file(params->x509_cred,
 449                                                    certfile, keyfile,
 450                                                    GNUTLS_X509_FMT_PEM);
 451         if (ret < 0) {
 452                 DEBUG(0,("TLS failed to initialise certfile %s and keyfile %s\n",
 453                          certfile, keyfile));
 454                 goto init_failed;
 455         }
 456
 457         ret = gnutls_dh_params_init(&params->dh_params);
 458         if (ret < 0) goto init_failed;
 459
 460         if (dhpfile && *dhpfile) {
 461                 gnutls_datum_t dhparms;
 462                 size_t size;
 463                 dhparms.data = (uint8_t *)file_load(dhpfile, &size, 0, mem_ctx);
 464
 465                 if (!dhparms.data) {
 466                         DEBUG(0,("Failed to read DH Parms from %s\n", dhpfile));
 467                         goto init_failed;
 468                 }
 469                 dhparms.size = size;
 470
 471                 ret = gnutls_dh_params_import_pkcs3(params->dh_params, &dhparms, GNUTLS_X509_FMT_PEM);
 472                 if (ret < 0) goto init_failed;
 473         } else {
 474                 ret = gnutls_dh_params_generate2(params->dh_params, DH_BITS);
 475                 if (ret < 0) goto init_failed;
 476         }
 477
 478         gnutls_certificate_set_dh_params(params->x509_cred, params->dh_params);
 479
 480         params->tls_enabled = true;
 481
 482         talloc_free(tmp_ctx);
 483         return params;
 484
 485 init_failed:
 486         DEBUG(0,("GNUTLS failed to initialise - %s\n", gnutls_strerror(ret)));
 487         params->tls_enabled = false;
 488         talloc_free(tmp_ctx);
 489         return params;
 490 }
 491
 492
 493 /*
 494   setup for a new connection
 495 */
 496 struct socket_context *tls_init_server(struct tls_params *params,
 497                                        struct socket_context *socket_ctx,
 498                                        struct tevent_fd *fde,
 499                                        const char *plain_chars)
 500 {
 501         struct tls_context *tls;
 502         int ret;
 503         struct socket_context *new_sock;
 504         NTSTATUS nt_status;
 505         const char *error_pos;
 506
 507         nt_status = socket_create_with_ops(socket_ctx, &tls_socket_ops, &new_sock,
 508                                            SOCKET_TYPE_STREAM,
 509                                            socket_ctx->flags | SOCKET_FLAG_ENCRYPT);
 510         if (!NT_STATUS_IS_OK(nt_status)) {
 511                 return NULL;
 512         }
 513
 514         tls = talloc(new_sock, struct tls_context);
 515         if (tls == NULL) {
 516                 return NULL;
 517         }
 518
 519         tls->socket          = socket_ctx;
 520         talloc_steal(tls, socket_ctx);
 521         tls->fde             = fde;
 522
 523         new_sock->private_data    = tls;
 524
 525         if (!params->tls_enabled) {
 526                 talloc_free(new_sock);
 527                 return NULL;
 528         }
 529
 530         TLSCHECK(gnutls_init(&tls->session, GNUTLS_SERVER));
 531
 532         talloc_set_destructor(tls, tls_destructor);
 533
 534         ret = gnutls_priority_set_direct(tls->session,
 535                                          params->tls_priority,
 536                                          &error_pos);
 537         if (ret != GNUTLS_E_SUCCESS) {
 538                 DEBUG(0,("TLS %s - %s.  Check 'tls priority' option at '%s'\n",
 539                          __location__, gnutls_strerror(ret), error_pos));
 540                 talloc_free(new_sock);
 541                 return NULL;
 542         }
 543
 544         TLSCHECK(gnutls_credentials_set(tls->session, GNUTLS_CRD_CERTIFICATE,
 545                                         params->x509_cred));
 546         gnutls_certificate_server_set_request(tls->session, GNUTLS_CERT_REQUEST);
 547         gnutls_dh_set_prime_bits(tls->session, DH_BITS);
 548         gnutls_transport_set_ptr(tls->session, (gnutls_transport_ptr)tls);
 549         gnutls_transport_set_pull_function(tls->session, (gnutls_pull_func)tls_pull);
 550         gnutls_transport_set_push_function(tls->session, (gnutls_push_func)tls_push);
 551 #if GNUTLS_VERSION_MAJOR < 3
 552         gnutls_transport_set_lowat(tls->session, 0);
 553 #endif
 554
 555         tls->plain_chars = plain_chars;
 556         if (plain_chars) {
 557                 tls->tls_detect = true;
 558         } else {
 559                 tls->tls_detect = false;
 560         }
 561
 562         tls->output_pending  = false;
 563         tls->done_handshake  = false;
 564         tls->have_first_byte = false;
 565         tls->tls_enabled     = true;
 566         tls->interrupted     = false;
 567
 568         new_sock->state = SOCKET_STATE_SERVER_CONNECTED;
 569
 570         return new_sock;
 571
 572 failed:
 573         DEBUG(0,("TLS init connection failed - %s\n", gnutls_strerror(ret)));
 574         talloc_free(new_sock);
 575         return NULL;
 576 }
 577
 578
 579 static NTSTATUS tls_socket_set_option(struct socket_context *sock, const char *option, const char *val)
 580 {
 581         set_socket_options(socket_get_fd(sock), option);
 582         return NT_STATUS_OK;
 583 }
 584
 585 static char *tls_socket_get_peer_name(struct socket_context *sock, TALLOC_CTX *mem_ctx)
 586 {
 587         struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
 588         return socket_get_peer_name(tls->socket, mem_ctx);
 589 }
 590
 591 static struct socket_address *tls_socket_get_peer_addr(struct socket_context *sock, TALLOC_CTX *mem_ctx)
 592 {
 593         struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
 594         return socket_get_peer_addr(tls->socket, mem_ctx);
 595 }
 596
 597 static struct socket_address *tls_socket_get_my_addr(struct socket_context *sock, TALLOC_CTX *mem_ctx)
 598 {
 599         struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
 600         return socket_get_my_addr(tls->socket, mem_ctx);
 601 }
 602
 603 static int tls_socket_get_fd(struct socket_context *sock)
 604 {
 605         struct tls_context *tls = talloc_get_type(sock->private_data, struct tls_context);
 606         return socket_get_fd(tls->socket);
 607 }
 608
 609 static const struct socket_ops tls_socket_ops = {
 610         .name                   = "tls",
 611         .fn_init                = tls_socket_init,
 612         .fn_recv                = tls_socket_recv,
 613         .fn_send                = tls_socket_send,
 614         .fn_pending             = tls_socket_pending,
 615
 616         .fn_set_option          = tls_socket_set_option,
 617
 618         .fn_get_peer_name       = tls_socket_get_peer_name,
 619         .fn_get_peer_addr       = tls_socket_get_peer_addr,
 620         .fn_get_my_addr         = tls_socket_get_my_addr,
 621         .fn_get_fd              = tls_socket_get_fd
 622 };
 623
 624 #else
 625
 626 /* for systems without tls we just fail the operations, and the caller
 627  * will retain the original socket */
 628
 629 struct tls_params *tls_initialise(TALLOC_CTX *mem_ctx, struct loadparm_context *lp_ctx)
 630 {
 631         return talloc_new(mem_ctx);
 632 }
 633
 634 /*
 635   setup for a new connection
 636 */
 637 struct socket_context *tls_init_server(struct tls_params *params,
 638                                     struct socket_context *socket,
 639                                     struct tevent_fd *fde,
 640                                     const char *plain_chars)
 641 {
 642         return NULL;
 643 }
 644
 645
 646 #endif
 647