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
 378         /* Note that response needs to be initialized to avoid
 379          * crashing on clean up after WINBINDD_PRIV_PIPE_DIR call failed
 380          * as interface version (from the first request) returned as a fstring,
 381          * thus response.extra_data.data will not be NULL even though
 382          * winbindd response did not write over it due to a failure */
 383         ZERO_STRUCT(response);
 384         if (winbindd_request_response(WINBINDD_PRIV_PIPE_DIR, &request, &response) == NSS_STATUS_SUCCESS) {
 385                 int fd;
 386                 if ((fd = winbind_named_pipe_sock((char *)response.extra_data.data)) != -1) {
 387                         close(winbindd_fd);
 388                         winbindd_fd = fd;
 389                         is_privileged = 1;
 390                 }
 391         }
 392
 393         if ((need_priv != 0) && (is_privileged == 0)) {
 394                 return -1;
 395         }
 396
 397         SAFE_FREE(response.extra_data.data);
 398
 399         return winbindd_fd;
 400 #else
 401         return -1;
 402 #endif /* HAVE_UNIXSOCKET */
 403 }
 404
 405 /* Write data to winbindd socket */
 406
 407 static int winbind_write_sock(void *buffer, int count, int recursing,
 408                               int need_priv)
 409 {
 410         int fd, result, nwritten;
 411
 412         /* Open connection to winbind daemon */
 413
 414  restart:
 415
 416         fd = winbind_open_pipe_sock(recursing, need_priv);
 417         if (fd == -1) {
 418                 errno = ENOENT;
 419                 return -1;
 420         }
 421
 422         /* Write data to socket */
 423
 424         nwritten = 0;
 425
 426         while(nwritten < count) {
 427                 struct pollfd pfd;
 428                 int ret;
 429
 430                 /* Catch pipe close on other end by checking if a read()
 431                    call would not block by calling poll(). */
 432
 433                 pfd.fd = fd;
 434                 pfd.events = POLLIN|POLLOUT|POLLHUP;
 435
 436                 ret = poll(&pfd, 1, -1);
 437                 if (ret == -1) {
 438                         winbind_close_sock();
 439                         return -1;                   /* poll error */
 440                 }
 441
 442                 /* Write should be OK if fd not available for reading */
 443
 444                 if ((ret == 1) && (pfd.revents & (POLLIN|POLLHUP|POLLERR))) {
 445
 446                         /* Pipe has closed on remote end */
 447
 448                         winbind_close_sock();
 449                         goto restart;
 450                 }
 451
 452                 /* Do the write */
 453
 454                 result = write(fd, (char *)buffer + nwritten,
 455                                count - nwritten);
 456
 457                 if ((result == -1) || (result == 0)) {
 458
 459                         /* Write failed */
 460
 461                         winbind_close_sock();
 462                         return -1;
 463                 }
 464
 465                 nwritten += result;
 466         }
 467
 468         return nwritten;
 469 }
 470
 471 /* Read data from winbindd socket */
 472
 473 static int winbind_read_sock(void *buffer, int count)
 474 {
 475         int fd;
 476         int nread = 0;
 477         int total_time = 0;
 478
 479         fd = winbind_open_pipe_sock(false, false);
 480         if (fd == -1) {
 481                 return -1;
 482         }
 483
 484         /* Read data from socket */
 485         while(nread < count) {
 486                 struct pollfd pfd;
 487                 int ret;
 488
 489                 /* Catch pipe close on other end by checking if a read()
 490                    call would not block by calling poll(). */
 491
 492                 pfd.fd = fd;
 493                 pfd.events = POLLIN|POLLHUP;
 494
 495                 /* Wait for 5 seconds for a reply. May need to parameterise this... */
 496
 497                 ret = poll(&pfd, 1, 5000);
 498                 if (ret == -1) {
 499                         winbind_close_sock();
 500                         return -1;                   /* poll error */
 501                 }
 502
 503                 if (ret == 0) {
 504                         /* Not ready for read yet... */
 505                         if (total_time >= 30) {
 506                                 /* Timeout */
 507                                 winbind_close_sock();
 508                                 return -1;
 509                         }
 510                         total_time += 5;
 511                         continue;
 512                 }
 513
 514                 if ((ret == 1) && (pfd.revents & (POLLIN|POLLHUP|POLLERR))) {
 515
 516                         /* Do the Read */
 517
 518                         int result = read(fd, (char *)buffer + nread,
 519                               count - nread);
 520
 521                         if ((result == -1) || (result == 0)) {
 522
 523                                 /* Read failed.  I think the only useful thing we
 524                                    can do here is just return -1 and fail since the
 525                                    transaction has failed half way through. */
 526
 527                                 winbind_close_sock();
 528                                 return -1;
 529                         }
 530
 531                         nread += result;
 532
 533                 }
 534         }
 535
 536         return nread;
 537 }
 538
 539 /* Read reply */
 540
 541 static int winbindd_read_reply(struct winbindd_response *response)
 542 {
 543         int result1, result2 = 0;
 544
 545         if (!response) {
 546                 return -1;
 547         }
 548
 549         /* Read fixed length response */
 550
 551         result1 = winbind_read_sock(response,
 552                                     sizeof(struct winbindd_response));
 553         if (result1 == -1) {
 554                 return -1;
 555         }
 556
 557         if (response->length < sizeof(struct winbindd_response)) {
 558                 return -1;
 559         }
 560
 561         /* We actually send the pointer value of the extra_data field from
 562            the server.  This has no meaning in the client's address space
 563            so we clear it out. */
 564
 565         response->extra_data.data = NULL;
 566
 567         /* Read variable length response */
 568
 569         if (response->length > sizeof(struct winbindd_response)) {
 570                 int extra_data_len = response->length -
 571                         sizeof(struct winbindd_response);
 572
 573                 /* Mallocate memory for extra data */
 574
 575                 if (!(response->extra_data.data = malloc(extra_data_len))) {
 576                         return -1;
 577                 }
 578
 579                 result2 = winbind_read_sock(response->extra_data.data,
 580                                             extra_data_len);
 581                 if (result2 == -1) {
 582                         winbindd_free_response(response);
 583                         return -1;
 584                 }
 585         }
 586
 587         /* Return total amount of data read */
 588
 589         return result1 + result2;
 590 }
 591
 592 /*
 593  * send simple types of requests
 594  */
 595
 596 NSS_STATUS winbindd_send_request(int req_type, int need_priv,
 597                                  struct winbindd_request *request)
 598 {
 599         struct winbindd_request lrequest;
 600
 601         /* Check for our tricky environment variable */
 602
 603         if (winbind_env_set()) {
 604                 return NSS_STATUS_NOTFOUND;
 605         }
 606
 607         if (!request) {
 608                 ZERO_STRUCT(lrequest);
 609                 request = &lrequest;
 610         }
 611
 612         /* Fill in request and send down pipe */
 613
 614         winbindd_init_request(request, req_type);
 615
 616         if (winbind_write_sock(request, sizeof(*request),
 617                                request->wb_flags & WBFLAG_RECURSE,
 618                                need_priv) == -1)
 619         {
 620                 /* Set ENOENT for consistency.  Required by some apps */
 621                 errno = ENOENT;
 622
 623                 return NSS_STATUS_UNAVAIL;
 624         }
 625
 626         if ((request->extra_len != 0) &&
 627             (winbind_write_sock(request->extra_data.data,
 628                                 request->extra_len,
 629                                 request->wb_flags & WBFLAG_RECURSE,
 630                                 need_priv) == -1))
 631         {
 632                 /* Set ENOENT for consistency.  Required by some apps */
 633                 errno = ENOENT;
 634
 635                 return NSS_STATUS_UNAVAIL;
 636         }
 637
 638         return NSS_STATUS_SUCCESS;
 639 }
 640
 641 /*
 642  * Get results from winbindd request
 643  */
 644
 645 NSS_STATUS winbindd_get_response(struct winbindd_response *response)
 646 {
 647         struct winbindd_response lresponse;
 648
 649         if (!response) {
 650                 ZERO_STRUCT(lresponse);
 651                 response = &lresponse;
 652         }
 653
 654         init_response(response);
 655
 656         /* Wait for reply */
 657         if (winbindd_read_reply(response) == -1) {
 658                 /* Set ENOENT for consistency.  Required by some apps */
 659                 errno = ENOENT;
 660
 661                 return NSS_STATUS_UNAVAIL;
 662         }
 663
 664         /* Throw away extra data if client didn't request it */
 665         if (response == &lresponse) {
 666                 winbindd_free_response(response);
 667         }
 668
 669         /* Copy reply data from socket */
 670         if (response->result != WINBINDD_OK) {
 671                 return NSS_STATUS_NOTFOUND;
 672         }
 673
 674         return NSS_STATUS_SUCCESS;
 675 }
 676
 677 /* Handle simple types of requests */
 678
 679 NSS_STATUS winbindd_request_response(int req_type,
 680                             struct winbindd_request *request,
 681                             struct winbindd_response *response)
 682 {
 683         NSS_STATUS status = NSS_STATUS_UNAVAIL;
 684         int count = 0;
 685
 686         while ((status == NSS_STATUS_UNAVAIL) && (count < 10)) {
 687                 status = winbindd_send_request(req_type, 0, request);
 688                 if (status != NSS_STATUS_SUCCESS)
 689                         return(status);
 690                 status = winbindd_get_response(response);
 691                 count += 1;
 692         }
 693
 694         return status;
 695 }
 696
 697 NSS_STATUS winbindd_priv_request_response(int req_type,
 698                                           struct winbindd_request *request,
 699                                           struct winbindd_response *response)
 700 {
 701         NSS_STATUS status = NSS_STATUS_UNAVAIL;
 702         int count = 0;
 703
 704         while ((status == NSS_STATUS_UNAVAIL) && (count < 10)) {
 705                 status = winbindd_send_request(req_type, 1, request);
 706                 if (status != NSS_STATUS_SUCCESS)
 707                         return(status);
 708                 status = winbindd_get_response(response);
 709                 count += 1;
 710         }
 711
 712         return status;
 713 }