nsswitch/wb_common.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    winbind client common code
   5
   6    Copyright (C) Tim Potter 2000
   7    Copyright (C) Andrew Tridgell 2000
   8    Copyright (C) Andrew Bartlett 2002
   9
  10
  11    This library is free software; you can redistribute it and/or
  12    modify it under the terms of the GNU Lesser General Public
  13    License as published by the Free Software Foundation; either
  14    version 3 of the License, or (at your option) any later version.
  15
  16    This library is distributed in the hope that it will be useful,
  17    but WITHOUT ANY WARRANTY; without even the implied warranty of
  18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19    Library General Public License for more details.
  20
  21    You should have received a copy of the GNU Lesser General Public License
  22    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  23 */
  24
  25 #include "replace.h"
  26 #include "system/select.h"
  27 #include "winbind_client.h"
  28
  29 /* Global variables.  These are effectively the client state information */
  30
  31 int winbindd_fd = -1;           /* fd for winbindd socket */
  32 static int is_privileged = 0;
  33
  34 /* Free a response structure */
  35
  36 void winbindd_free_response(struct winbindd_response *response)
  37 {
  38         /* Free any allocated extra_data */
  39
  40         if (response)
  41                 SAFE_FREE(response->extra_data.data);
  42 }
  43
  44 /* Initialise a request structure */
  45
  46 static void winbindd_init_request(struct winbindd_request *request,
  47                                   int request_type)
  48 {
  49         request->length = sizeof(struct winbindd_request);
  50
  51         request->cmd = (enum winbindd_cmd)request_type;
  52         request->pid = getpid();
  53
  54 }
  55
  56 /* Initialise a response structure */
  57
  58 static void init_response(struct winbindd_response *response)
  59 {
  60         /* Initialise return value */
  61
  62         response->result = WINBINDD_ERROR;
  63 }
  64
  65 /* Close established socket */
  66
  67 #if HAVE_FUNCTION_ATTRIBUTE_DESTRUCTOR
  68 __attribute__((destructor))
  69 #endif
  70 static void winbind_close_sock(void)
  71 {
  72         if (winbindd_fd != -1) {
  73                 close(winbindd_fd);
  74                 winbindd_fd = -1;
  75         }
  76 }
  77
  78 #define CONNECT_TIMEOUT 30
  79
  80 /* Make sure socket handle isn't stdin, stdout or stderr */
  81 #define RECURSION_LIMIT 3
  82
  83 static int make_nonstd_fd_internals(int fd, int limit /* Recursion limiter */)
  84 {
  85         int new_fd;
  86         if (fd >= 0 && fd <= 2) {
  87 #ifdef F_DUPFD
  88                 if ((new_fd = fcntl(fd, F_DUPFD, 3)) == -1) {
  89                         return -1;
  90                 }
  91                 /* Paranoia */
  92                 if (new_fd < 3) {
  93                         close(new_fd);
  94                         return -1;
  95                 }
  96                 close(fd);
  97                 return new_fd;
  98 #else
  99                 if (limit <= 0)
 100                         return -1;
 101
 102                 new_fd = dup(fd);
 103                 if (new_fd == -1)
 104                         return -1;
 105
 106                 /* use the program stack to hold our list of FDs to close */
 107                 new_fd = make_nonstd_fd_internals(new_fd, limit - 1);
 108                 close(fd);
 109                 return new_fd;
 110 #endif
 111         }
 112         return fd;
 113 }
 114
 115 /****************************************************************************
 116  Set a fd into blocking/nonblocking mode. Uses POSIX O_NONBLOCK if available,
 117  else
 118  if SYSV use O_NDELAY
 119  if BSD use FNDELAY
 120  Set close on exec also.
 121 ****************************************************************************/
 122
 123 static int make_safe_fd(int fd)
 124 {
 125         int result, flags;
 126         int new_fd = make_nonstd_fd_internals(fd, RECURSION_LIMIT);
 127         if (new_fd == -1) {
 128                 close(fd);
 129                 return -1;
 130         }
 131
 132         /* Socket should be nonblocking. */
 133 #ifdef O_NONBLOCK
 134 #define FLAG_TO_SET O_NONBLOCK
 135 #else
 136 #ifdef SYSV
 137 #define FLAG_TO_SET O_NDELAY
 138 #else /* BSD */
 139 #define FLAG_TO_SET FNDELAY
 140 #endif
 141 #endif
 142
 143         if ((flags = fcntl(new_fd, F_GETFL)) == -1) {
 144                 close(new_fd);
 145                 return -1;
 146         }
 147
 148         flags |= FLAG_TO_SET;
 149         if (fcntl(new_fd, F_SETFL, flags) == -1) {
 150                 close(new_fd);
 151                 return -1;
 152         }
 153
 154 #undef FLAG_TO_SET
 155
 156         /* Socket should be closed on exec() */
 157 #ifdef FD_CLOEXEC
 158         result = flags = fcntl(new_fd, F_GETFD, 0);
 159         if (flags >= 0) {
 160                 flags |= FD_CLOEXEC;
 161                 result = fcntl( new_fd, F_SETFD, flags );
 162         }
 163         if (result < 0) {
 164                 close(new_fd);
 165                 return -1;
 166         }
 167 #endif
 168         return new_fd;
 169 }
 170
 171 /**
 172  * @internal
 173  *
 174  * @brief Check if we have priviliged access.
 175  *
 176  * This checks if we have uid_wrapper running and if yes turns it of so that we
 177  * can check if we have access.
 178  *
 179  * @param[in]  uid      The uid to compare if we have access.
 180  *
 181  * @return              If we have access it returns true, else false.
 182  */
 183 static bool winbind_privileged_access(uid_t uid)
 184 {
 185         uid_t euid;
 186
 187         if (uid_wrapper_enabled()) {
 188                 setenv("UID_WRAPPER_MYUID", "1", 1);
 189         }
 190
 191         euid = geteuid();
 192
 193         if (uid_wrapper_enabled()) {
 194                 unsetenv("UID_WRAPPER_MYUID");
 195         }
 196
 197         return (uid == euid);
 198 }
 199
 200 /* Connect to winbindd socket */
 201
 202 static int winbind_named_pipe_sock(const char *dir)
 203 {
 204         struct sockaddr_un sunaddr;
 205         struct stat st;
 206         char *path = NULL;
 207         int fd;
 208         int wait_time;
 209         int slept;
 210
 211         /* Check permissions on unix socket directory */
 212
 213         if (lstat(dir, &st) == -1) {
 214                 errno = ENOENT;
 215                 return -1;
 216         }
 217
 218         /* This tells uid_wrapper to return the userid for the geteuid check */
 219         if (!S_ISDIR(st.st_mode) ||
 220             !winbind_privileged_access(st.st_uid)) {
 221                 errno = ENOENT;
 222                 return -1;
 223         }
 224
 225         /* Connect to socket */
 226
 227         if (asprintf(&path, "%s/%s", dir, WINBINDD_SOCKET_NAME) < 0) {
 228                 return -1;
 229         }
 230
 231         ZERO_STRUCT(sunaddr);
 232         sunaddr.sun_family = AF_UNIX;
 233         strncpy(sunaddr.sun_path, path, sizeof(sunaddr.sun_path) - 1);
 234
 235         /* If socket file doesn't exist, don't bother trying to connect
 236            with retry.  This is an attempt to make the system usable when
 237            the winbindd daemon is not running. */
 238
 239         if (lstat(path, &st) == -1) {
 240                 errno = ENOENT;
 241                 SAFE_FREE(path);
 242                 return -1;
 243         }
 244
 245         SAFE_FREE(path);
 246         /* Check permissions on unix socket file */
 247
 248         /* This tells uid_wrapper to return the userid for the geteuid check */
 249         if (!S_ISSOCK(st.st_mode) ||
 250             !winbind_privileged_access(st.st_uid)) {
 251                 errno = ENOENT;
 252                 return -1;
 253         }
 254
 255         /* Connect to socket */
 256
 257         if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
 258                 return -1;
 259         }
 260
 261         /* Set socket non-blocking and close on exec. */
 262
 263         if ((fd = make_safe_fd( fd)) == -1) {
 264                 return fd;
 265         }
 266
 267         for (wait_time = 0; connect(fd, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) == -1;
 268                         wait_time += slept) {
 269                 struct pollfd pfd;
 270                 int ret;
 271                 int connect_errno = 0;
 272                 socklen_t errnosize;
 273
 274                 if (wait_time >= CONNECT_TIMEOUT)
 275                         goto error_out;
 276
 277                 switch (errno) {
 278                         case EINPROGRESS:
 279                                 pfd.fd = fd;
 280                                 pfd.events = POLLOUT;
 281
 282                                 ret = poll(&pfd, 1, (CONNECT_TIMEOUT - wait_time) * 1000);
 283
 284                                 if (ret > 0) {
 285                                         errnosize = sizeof(connect_errno);
 286
 287                                         ret = getsockopt(fd, SOL_SOCKET,
 288                                                         SO_ERROR, &connect_errno, &errnosize);
 289
 290                                         if (ret >= 0 && connect_errno == 0) {
 291                                                 /* Connect succeed */
 292                                                 goto out;
 293                                         }
 294                                 }
 295
 296                                 slept = CONNECT_TIMEOUT;
 297                                 break;
 298                         case EAGAIN:
 299                                 slept = rand() % 3 + 1;
 300                                 sleep(slept);
 301                                 break;
 302                         default:
 303                                 goto error_out;
 304                 }
 305
 306         }
 307
 308   out:
 309
 310         return fd;
 311
 312   error_out:
 313
 314         close(fd);
 315         return -1;
 316 }
 317
 318 static const char *winbindd_socket_dir(void)
 319 {
 320         if (nss_wrapper_enabled()) {
 321                 const char *env_dir;
 322
 323                 env_dir = getenv("SELFTEST_WINBINDD_SOCKET_DIR");
 324                 if (env_dir != NULL) {
 325                         return env_dir;
 326                 }
 327         }
 328
 329         return WINBINDD_SOCKET_DIR;
 330 }
 331
 332 /* Connect to winbindd socket */
 333
 334 static int winbind_open_pipe_sock(int recursing, int need_priv)
 335 {
 336 #ifdef HAVE_UNIXSOCKET
 337         static pid_t our_pid;
 338         struct winbindd_request request;
 339         struct winbindd_response response;
 340         ZERO_STRUCT(request);
 341         ZERO_STRUCT(response);
 342
 343         if (our_pid != getpid()) {
 344                 winbind_close_sock();
 345                 our_pid = getpid();
 346         }
 347
 348         if ((need_priv != 0) && (is_privileged == 0)) {
 349                 winbind_close_sock();
 350         }
 351
 352         if (winbindd_fd != -1) {
 353                 return winbindd_fd;
 354         }
 355
 356         if (recursing) {
 357                 return -1;
 358         }
 359
 360         if ((winbindd_fd = winbind_named_pipe_sock(winbindd_socket_dir())) == -1) {
 361                 return -1;
 362         }
 363
 364         is_privileged = 0;
 365
 366         /* version-check the socket */
 367
 368         request.wb_flags = WBFLAG_RECURSE;
 369         if ((winbindd_request_response(WINBINDD_INTERFACE_VERSION, &request, &response) != NSS_STATUS_SUCCESS) || (response.data.interface_version != WINBIND_INTERFACE_VERSION)) {
 370                 winbind_close_sock();
 371                 return -1;
 372         }
 373
 374         /* try and get priv pipe */
 375
 376         request.wb_flags = WBFLAG_RECURSE;
 377         if (winbindd_request_response(WINBINDD_PRIV_PIPE_DIR, &request, &response) == NSS_STATUS_SUCCESS) {
 378                 int fd;
 379                 if ((fd = winbind_named_pipe_sock((char *)response.extra_data.data)) != -1) {
 380                         close(winbindd_fd);
 381                         winbindd_fd = fd;
 382                         is_privileged = 1;
 383                 }
 384         }
 385
 386         if ((need_priv != 0) && (is_privileged == 0)) {
 387                 return -1;
 388         }
 389
 390         SAFE_FREE(response.extra_data.data);
 391
 392         return winbindd_fd;
 393 #else
 394         return -1;
 395 #endif /* HAVE_UNIXSOCKET */
 396 }
 397
 398 /* Write data to winbindd socket */
 399
 400 static int winbind_write_sock(void *buffer, int count, int recursing,
 401                               int need_priv)
 402 {
 403         int fd, result, nwritten;
 404
 405         /* Open connection to winbind daemon */
 406
 407  restart:
 408
 409         fd = winbind_open_pipe_sock(recursing, need_priv);
 410         if (fd == -1) {
 411                 errno = ENOENT;
 412                 return -1;
 413         }
 414
 415         /* Write data to socket */
 416
 417         nwritten = 0;
 418
 419         while(nwritten < count) {
 420                 struct pollfd pfd;
 421                 int ret;
 422
 423                 /* Catch pipe close on other end by checking if a read()
 424                    call would not block by calling poll(). */
 425
 426                 pfd.fd = fd;
 427                 pfd.events = POLLIN|POLLOUT|POLLHUP;
 428
 429                 ret = poll(&pfd, 1, -1);
 430                 if (ret == -1) {
 431                         winbind_close_sock();
 432                         return -1;                   /* poll error */
 433                 }
 434
 435                 /* Write should be OK if fd not available for reading */
 436
 437                 if ((ret == 1) && (pfd.revents & (POLLIN|POLLHUP|POLLERR))) {
 438
 439                         /* Pipe has closed on remote end */
 440
 441                         winbind_close_sock();
 442                         goto restart;
 443                 }
 444
 445                 /* Do the write */
 446
 447                 result = write(fd, (char *)buffer + nwritten,
 448                                count - nwritten);
 449
 450                 if ((result == -1) || (result == 0)) {
 451
 452                         /* Write failed */
 453
 454                         winbind_close_sock();
 455                         return -1;
 456                 }
 457
 458                 nwritten += result;
 459         }
 460
 461         return nwritten;
 462 }
 463
 464 /* Read data from winbindd socket */
 465
 466 static int winbind_read_sock(void *buffer, int count)
 467 {
 468         int fd;
 469         int nread = 0;
 470         int total_time = 0;
 471
 472         fd = winbind_open_pipe_sock(false, false);
 473         if (fd == -1) {
 474                 return -1;
 475         }
 476
 477         /* Read data from socket */
 478         while(nread < count) {
 479                 struct pollfd pfd;
 480                 int ret;
 481
 482                 /* Catch pipe close on other end by checking if a read()
 483                    call would not block by calling poll(). */
 484
 485                 pfd.fd = fd;
 486                 pfd.events = POLLIN|POLLHUP;
 487
 488                 /* Wait for 5 seconds for a reply. May need to parameterise this... */
 489
 490                 ret = poll(&pfd, 1, 5000);
 491                 if (ret == -1) {
 492                         winbind_close_sock();
 493                         return -1;                   /* poll error */
 494                 }
 495
 496                 if (ret == 0) {
 497                         /* Not ready for read yet... */
 498                         if (total_time >= 30) {
 499                                 /* Timeout */
 500                                 winbind_close_sock();
 501                                 return -1;
 502                         }
 503                         total_time += 5;
 504                         continue;
 505                 }
 506
 507                 if ((ret == 1) && (pfd.revents & (POLLIN|POLLHUP|POLLERR))) {
 508
 509                         /* Do the Read */
 510
 511                         int result = read(fd, (char *)buffer + nread,
 512                               count - nread);
 513
 514                         if ((result == -1) || (result == 0)) {
 515
 516                                 /* Read failed.  I think the only useful thing we
 517                                    can do here is just return -1 and fail since the
 518                                    transaction has failed half way through. */
 519
 520                                 winbind_close_sock();
 521                                 return -1;
 522                         }
 523
 524                         nread += result;
 525
 526                 }
 527         }
 528
 529         return nread;
 530 }
 531
 532 /* Read reply */
 533
 534 static int winbindd_read_reply(struct winbindd_response *response)
 535 {
 536         int result1, result2 = 0;
 537
 538         if (!response) {
 539                 return -1;
 540         }
 541
 542         /* Read fixed length response */
 543
 544         result1 = winbind_read_sock(response,
 545                                     sizeof(struct winbindd_response));
 546         if (result1 == -1) {
 547                 return -1;
 548         }
 549
 550         if (response->length < sizeof(struct winbindd_response)) {
 551                 return -1;
 552         }
 553
 554         /* We actually send the pointer value of the extra_data field from
 555            the server.  This has no meaning in the client's address space
 556            so we clear it out. */
 557
 558         response->extra_data.data = NULL;
 559
 560         /* Read variable length response */
 561
 562         if (response->length > sizeof(struct winbindd_response)) {
 563                 int extra_data_len = response->length -
 564                         sizeof(struct winbindd_response);
 565
 566                 /* Mallocate memory for extra data */
 567
 568                 if (!(response->extra_data.data = malloc(extra_data_len))) {
 569                         return -1;
 570                 }
 571
 572                 result2 = winbind_read_sock(response->extra_data.data,
 573                                             extra_data_len);
 574                 if (result2 == -1) {
 575                         winbindd_free_response(response);
 576                         return -1;
 577                 }
 578         }
 579
 580         /* Return total amount of data read */
 581
 582         return result1 + result2;
 583 }
 584
 585 /*
 586  * send simple types of requests
 587  */
 588
 589 NSS_STATUS winbindd_send_request(int req_type, int need_priv,
 590                                  struct winbindd_request *request)
 591 {
 592         struct winbindd_request lrequest;
 593
 594         /* Check for our tricky environment variable */
 595
 596         if (winbind_env_set()) {
 597                 return NSS_STATUS_NOTFOUND;
 598         }
 599
 600         if (!request) {
 601                 ZERO_STRUCT(lrequest);
 602                 request = &lrequest;
 603         }
 604
 605         /* Fill in request and send down pipe */
 606
 607         winbindd_init_request(request, req_type);
 608
 609         if (winbind_write_sock(request, sizeof(*request),
 610                                request->wb_flags & WBFLAG_RECURSE,
 611                                need_priv) == -1)
 612         {
 613                 /* Set ENOENT for consistency.  Required by some apps */
 614                 errno = ENOENT;
 615
 616                 return NSS_STATUS_UNAVAIL;
 617         }
 618
 619         if ((request->extra_len != 0) &&
 620             (winbind_write_sock(request->extra_data.data,
 621                                 request->extra_len,
 622                                 request->wb_flags & WBFLAG_RECURSE,
 623                                 need_priv) == -1))
 624         {
 625                 /* Set ENOENT for consistency.  Required by some apps */
 626                 errno = ENOENT;
 627
 628                 return NSS_STATUS_UNAVAIL;
 629         }
 630
 631         return NSS_STATUS_SUCCESS;
 632 }
 633
 634 /*
 635  * Get results from winbindd request
 636  */
 637
 638 NSS_STATUS winbindd_get_response(struct winbindd_response *response)
 639 {
 640         struct winbindd_response lresponse;
 641
 642         if (!response) {
 643                 ZERO_STRUCT(lresponse);
 644                 response = &lresponse;
 645         }
 646
 647         init_response(response);
 648
 649         /* Wait for reply */
 650         if (winbindd_read_reply(response) == -1) {
 651                 /* Set ENOENT for consistency.  Required by some apps */
 652                 errno = ENOENT;
 653
 654                 return NSS_STATUS_UNAVAIL;
 655         }
 656
 657         /* Throw away extra data if client didn't request it */
 658         if (response == &lresponse) {
 659                 winbindd_free_response(response);
 660         }
 661
 662         /* Copy reply data from socket */
 663         if (response->result != WINBINDD_OK) {
 664                 return NSS_STATUS_NOTFOUND;
 665         }
 666
 667         return NSS_STATUS_SUCCESS;
 668 }
 669
 670 /* Handle simple types of requests */
 671
 672 NSS_STATUS winbindd_request_response(int req_type,
 673                             struct winbindd_request *request,
 674                             struct winbindd_response *response)
 675 {
 676         NSS_STATUS status = NSS_STATUS_UNAVAIL;
 677         int count = 0;
 678
 679         while ((status == NSS_STATUS_UNAVAIL) && (count < 10)) {
 680                 status = winbindd_send_request(req_type, 0, request);
 681                 if (status != NSS_STATUS_SUCCESS)
 682                         return(status);
 683                 status = winbindd_get_response(response);
 684                 count += 1;
 685         }
 686
 687         return status;
 688 }
 689
 690 NSS_STATUS winbindd_priv_request_response(int req_type,
 691                                           struct winbindd_request *request,
 692                                           struct winbindd_response *response)
 693 {
 694         NSS_STATUS status = NSS_STATUS_UNAVAIL;
 695         int count = 0;
 696
 697         while ((status == NSS_STATUS_UNAVAIL) && (count < 10)) {
 698                 status = winbindd_send_request(req_type, 1, request);
 699                 if (status != NSS_STATUS_SUCCESS)
 700                         return(status);
 701                 status = winbindd_get_response(response);
 702                 count += 1;
 703         }
 704
 705         return status;
 706 }