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 talk to the priviliged pipe which should be owned by root.
 175  *
 176  * This checks if we have uid_wrapper running and if this is the case it will
 177  * allow to connect to the winbind privileged pipe even it is not owned by root.
 178  *
 179  * @param[in]  uid      The uid to check if we can safely talk to the pipe.
 180  *
 181  * @return              If we have access it returns true, else false.
 182  */
 183 static bool winbind_privileged_pipe_is_root(uid_t uid)
 184 {
 185         if (uid == 0) {
 186                 return true;
 187         }
 188
 189         if (uid_wrapper_enabled()) {
 190                 return true;
 191         }
 192
 193         return false;
 194 }
 195
 196 /* Connect to winbindd socket */
 197
 198 static int winbind_named_pipe_sock(const char *dir)
 199 {
 200         struct sockaddr_un sunaddr;
 201         struct stat st;
 202         char *path = NULL;
 203         int fd;
 204         int wait_time;
 205         int slept;
 206
 207         /* Check permissions on unix socket directory */
 208
 209         if (lstat(dir, &st) == -1) {
 210                 errno = ENOENT;
 211                 return -1;
 212         }
 213
 214         /*
 215          * This tells us that the pipe is owned by a privileged
 216          * process, as we will be sending passwords to it.
 217          */
 218         if (!S_ISDIR(st.st_mode) ||
 219             !winbind_privileged_pipe_is_root(st.st_uid)) {
 220                 errno = ENOENT;
 221                 return -1;
 222         }
 223
 224         /* Connect to socket */
 225
 226         if (asprintf(&path, "%s/%s", dir, WINBINDD_SOCKET_NAME) < 0) {
 227                 return -1;
 228         }
 229
 230         ZERO_STRUCT(sunaddr);
 231         sunaddr.sun_family = AF_UNIX;
 232         strncpy(sunaddr.sun_path, path, sizeof(sunaddr.sun_path) - 1);
 233
 234         /* If socket file doesn't exist, don't bother trying to connect
 235            with retry.  This is an attempt to make the system usable when
 236            the winbindd daemon is not running. */
 237
 238         if (lstat(path, &st) == -1) {
 239                 errno = ENOENT;
 240                 SAFE_FREE(path);
 241                 return -1;
 242         }
 243
 244         SAFE_FREE(path);
 245         /* Check permissions on unix socket file */
 246
 247         /*
 248          * This tells us that the pipe is owned by a privileged
 249          * process, as we will be sending passwords to it.
 250          */
 251         if (!S_ISSOCK(st.st_mode) ||
 252             !winbind_privileged_pipe_is_root(st.st_uid)) {
 253                 errno = ENOENT;
 254                 return -1;
 255         }
 256
 257         /* Connect to socket */
 258
 259         if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
 260                 return -1;
 261         }
 262
 263         /* Set socket non-blocking and close on exec. */
 264
 265         if ((fd = make_safe_fd( fd)) == -1) {
 266                 return fd;
 267         }
 268
 269         for (wait_time = 0; connect(fd, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) == -1;
 270                         wait_time += slept) {
 271                 struct pollfd pfd;
 272                 int ret;
 273                 int connect_errno = 0;
 274                 socklen_t errnosize;
 275
 276                 if (wait_time >= CONNECT_TIMEOUT)
 277                         goto error_out;
 278
 279                 switch (errno) {
 280                         case EINPROGRESS:
 281                                 pfd.fd = fd;
 282                                 pfd.events = POLLOUT;
 283
 284                                 ret = poll(&pfd, 1, (CONNECT_TIMEOUT - wait_time) * 1000);
 285
 286                                 if (ret > 0) {
 287                                         errnosize = sizeof(connect_errno);
 288
 289                                         ret = getsockopt(fd, SOL_SOCKET,
 290                                                         SO_ERROR, &connect_errno, &errnosize);
 291
 292                                         if (ret >= 0 && connect_errno == 0) {
 293                                                 /* Connect succeed */
 294                                                 goto out;
 295                                         }
 296                                 }
 297
 298                                 slept = CONNECT_TIMEOUT;
 299                                 break;
 300                         case EAGAIN:
 301                                 slept = rand() % 3 + 1;
 302                                 sleep(slept);
 303                                 break;
 304                         default:
 305                                 goto error_out;
 306                 }
 307
 308         }
 309
 310   out:
 311
 312         return fd;
 313
 314   error_out:
 315
 316         close(fd);
 317         return -1;
 318 }
 319
 320 static const char *winbindd_socket_dir(void)
 321 {
 322         if (nss_wrapper_enabled()) {
 323                 const char *env_dir;
 324
 325                 env_dir = getenv("SELFTEST_WINBINDD_SOCKET_DIR");
 326                 if (env_dir != NULL) {
 327                         return env_dir;
 328                 }
 329         }
 330
 331         return WINBINDD_SOCKET_DIR;
 332 }
 333
 334 /* Connect to winbindd socket */
 335
 336 static int winbind_open_pipe_sock(int recursing, int need_priv)
 337 {
 338 #ifdef HAVE_UNIXSOCKET
 339         static pid_t our_pid;
 340         struct winbindd_request request;
 341         struct winbindd_response response;
 342         ZERO_STRUCT(request);
 343         ZERO_STRUCT(response);
 344
 345         if (our_pid != getpid()) {
 346                 winbind_close_sock();
 347                 our_pid = getpid();
 348         }
 349
 350         if ((need_priv != 0) && (is_privileged == 0)) {
 351                 winbind_close_sock();
 352         }
 353
 354         if (winbindd_fd != -1) {
 355                 return winbindd_fd;
 356         }
 357
 358         if (recursing) {
 359                 return -1;
 360         }
 361
 362         if ((winbindd_fd = winbind_named_pipe_sock(winbindd_socket_dir())) == -1) {
 363                 return -1;
 364         }
 365
 366         is_privileged = 0;
 367
 368         /* version-check the socket */
 369
 370         request.wb_flags = WBFLAG_RECURSE;
 371         if ((winbindd_request_response(WINBINDD_INTERFACE_VERSION, &request, &response) != NSS_STATUS_SUCCESS) || (response.data.interface_version != WINBIND_INTERFACE_VERSION)) {
 372                 winbind_close_sock();
 373                 return -1;
 374         }
 375
 376         /* try and get priv pipe */
 377
 378         request.wb_flags = WBFLAG_RECURSE;
 379
 380         /* Note that response needs to be initialized to avoid
 381          * crashing on clean up after WINBINDD_PRIV_PIPE_DIR call failed
 382          * as interface version (from the first request) returned as a fstring,
 383          * thus response.extra_data.data will not be NULL even though
 384          * winbindd response did not write over it due to a failure */
 385         ZERO_STRUCT(response);
 386         if (winbindd_request_response(WINBINDD_PRIV_PIPE_DIR, &request, &response) == NSS_STATUS_SUCCESS) {
 387                 int fd;
 388                 if ((fd = winbind_named_pipe_sock((char *)response.extra_data.data)) != -1) {
 389                         close(winbindd_fd);
 390                         winbindd_fd = fd;
 391                         is_privileged = 1;
 392                 }
 393         }
 394
 395         if ((need_priv != 0) && (is_privileged == 0)) {
 396                 return -1;
 397         }
 398
 399         SAFE_FREE(response.extra_data.data);
 400
 401         return winbindd_fd;
 402 #else
 403         return -1;
 404 #endif /* HAVE_UNIXSOCKET */
 405 }
 406
 407 /* Write data to winbindd socket */
 408
 409 static int winbind_write_sock(void *buffer, int count, int recursing,
 410                               int need_priv)
 411 {
 412         int fd, result, nwritten;
 413
 414         /* Open connection to winbind daemon */
 415
 416  restart:
 417
 418         fd = winbind_open_pipe_sock(recursing, need_priv);
 419         if (fd == -1) {
 420                 errno = ENOENT;
 421                 return -1;
 422         }
 423
 424         /* Write data to socket */
 425
 426         nwritten = 0;
 427
 428         while(nwritten < count) {
 429                 struct pollfd pfd;
 430                 int ret;
 431
 432                 /* Catch pipe close on other end by checking if a read()
 433                    call would not block by calling poll(). */
 434
 435                 pfd.fd = fd;
 436                 pfd.events = POLLIN|POLLOUT|POLLHUP;
 437
 438                 ret = poll(&pfd, 1, -1);
 439                 if (ret == -1) {
 440                         winbind_close_sock();
 441                         return -1;                   /* poll error */
 442                 }
 443
 444                 /* Write should be OK if fd not available for reading */
 445
 446                 if ((ret == 1) && (pfd.revents & (POLLIN|POLLHUP|POLLERR))) {
 447
 448                         /* Pipe has closed on remote end */
 449
 450                         winbind_close_sock();
 451                         goto restart;
 452                 }
 453
 454                 /* Do the write */
 455
 456                 result = write(fd, (char *)buffer + nwritten,
 457                                count - nwritten);
 458
 459                 if ((result == -1) || (result == 0)) {
 460
 461                         /* Write failed */
 462
 463                         winbind_close_sock();
 464                         return -1;
 465                 }
 466
 467                 nwritten += result;
 468         }
 469
 470         return nwritten;
 471 }
 472
 473 /* Read data from winbindd socket */
 474
 475 static int winbind_read_sock(void *buffer, int count)
 476 {
 477         int fd;
 478         int nread = 0;
 479         int total_time = 0;
 480
 481         fd = winbind_open_pipe_sock(false, false);
 482         if (fd == -1) {
 483                 return -1;
 484         }
 485
 486         /* Read data from socket */
 487         while(nread < count) {
 488                 struct pollfd pfd;
 489                 int ret;
 490
 491                 /* Catch pipe close on other end by checking if a read()
 492                    call would not block by calling poll(). */
 493
 494                 pfd.fd = fd;
 495                 pfd.events = POLLIN|POLLHUP;
 496
 497                 /* Wait for 5 seconds for a reply. May need to parameterise this... */
 498
 499                 ret = poll(&pfd, 1, 5000);
 500                 if (ret == -1) {
 501                         winbind_close_sock();
 502                         return -1;                   /* poll error */
 503                 }
 504
 505                 if (ret == 0) {
 506                         /* Not ready for read yet... */
 507                         if (total_time >= 30) {
 508                                 /* Timeout */
 509                                 winbind_close_sock();
 510                                 return -1;
 511                         }
 512                         total_time += 5;
 513                         continue;
 514                 }
 515
 516                 if ((ret == 1) && (pfd.revents & (POLLIN|POLLHUP|POLLERR))) {
 517
 518                         /* Do the Read */
 519
 520                         int result = read(fd, (char *)buffer + nread,
 521                               count - nread);
 522
 523                         if ((result == -1) || (result == 0)) {
 524
 525                                 /* Read failed.  I think the only useful thing we
 526                                    can do here is just return -1 and fail since the
 527                                    transaction has failed half way through. */
 528
 529                                 winbind_close_sock();
 530                                 return -1;
 531                         }
 532
 533                         nread += result;
 534
 535                 }
 536         }
 537
 538         return nread;
 539 }
 540
 541 /* Read reply */
 542
 543 static int winbindd_read_reply(struct winbindd_response *response)
 544 {
 545         int result1, result2 = 0;
 546
 547         if (!response) {
 548                 return -1;
 549         }
 550
 551         /* Read fixed length response */
 552
 553         result1 = winbind_read_sock(response,
 554                                     sizeof(struct winbindd_response));
 555
 556         /* We actually send the pointer value of the extra_data field from
 557            the server.  This has no meaning in the client's address space
 558            so we clear it out. */
 559
 560         response->extra_data.data = NULL;
 561
 562         if (result1 == -1) {
 563                 return -1;
 564         }
 565
 566         if (response->length < sizeof(struct winbindd_response)) {
 567                 return -1;
 568         }
 569
 570         /* Read variable length response */
 571
 572         if (response->length > sizeof(struct winbindd_response)) {
 573                 int extra_data_len = response->length -
 574                         sizeof(struct winbindd_response);
 575
 576                 /* Mallocate memory for extra data */
 577
 578                 if (!(response->extra_data.data = malloc(extra_data_len))) {
 579                         return -1;
 580                 }
 581
 582                 result2 = winbind_read_sock(response->extra_data.data,
 583                                             extra_data_len);
 584                 if (result2 == -1) {
 585                         winbindd_free_response(response);
 586                         return -1;
 587                 }
 588         }
 589
 590         /* Return total amount of data read */
 591
 592         return result1 + result2;
 593 }
 594
 595 /*
 596  * send simple types of requests
 597  */
 598
 599 NSS_STATUS winbindd_send_request(int req_type, int need_priv,
 600                                  struct winbindd_request *request)
 601 {
 602         struct winbindd_request lrequest;
 603
 604         /* Check for our tricky environment variable */
 605
 606         if (winbind_env_set()) {
 607                 return NSS_STATUS_NOTFOUND;
 608         }
 609
 610         if (!request) {
 611                 ZERO_STRUCT(lrequest);
 612                 request = &lrequest;
 613         }
 614
 615         /* Fill in request and send down pipe */
 616
 617         winbindd_init_request(request, req_type);
 618
 619         if (winbind_write_sock(request, sizeof(*request),
 620                                request->wb_flags & WBFLAG_RECURSE,
 621                                need_priv) == -1)
 622         {
 623                 /* Set ENOENT for consistency.  Required by some apps */
 624                 errno = ENOENT;
 625
 626                 return NSS_STATUS_UNAVAIL;
 627         }
 628
 629         if ((request->extra_len != 0) &&
 630             (winbind_write_sock(request->extra_data.data,
 631                                 request->extra_len,
 632                                 request->wb_flags & WBFLAG_RECURSE,
 633                                 need_priv) == -1))
 634         {
 635                 /* Set ENOENT for consistency.  Required by some apps */
 636                 errno = ENOENT;
 637
 638                 return NSS_STATUS_UNAVAIL;
 639         }
 640
 641         return NSS_STATUS_SUCCESS;
 642 }
 643
 644 /*
 645  * Get results from winbindd request
 646  */
 647
 648 NSS_STATUS winbindd_get_response(struct winbindd_response *response)
 649 {
 650         struct winbindd_response lresponse;
 651
 652         if (!response) {
 653                 ZERO_STRUCT(lresponse);
 654                 response = &lresponse;
 655         }
 656
 657         init_response(response);
 658
 659         /* Wait for reply */
 660         if (winbindd_read_reply(response) == -1) {
 661                 /* Set ENOENT for consistency.  Required by some apps */
 662                 errno = ENOENT;
 663
 664                 return NSS_STATUS_UNAVAIL;
 665         }
 666
 667         /* Throw away extra data if client didn't request it */
 668         if (response == &lresponse) {
 669                 winbindd_free_response(response);
 670         }
 671
 672         /* Copy reply data from socket */
 673         if (response->result != WINBINDD_OK) {
 674                 return NSS_STATUS_NOTFOUND;
 675         }
 676
 677         return NSS_STATUS_SUCCESS;
 678 }
 679
 680 /* Handle simple types of requests */
 681
 682 NSS_STATUS winbindd_request_response(int req_type,
 683                             struct winbindd_request *request,
 684                             struct winbindd_response *response)
 685 {
 686         NSS_STATUS status = NSS_STATUS_UNAVAIL;
 687         int count = 0;
 688
 689         while ((status == NSS_STATUS_UNAVAIL) && (count < 10)) {
 690                 status = winbindd_send_request(req_type, 0, request);
 691                 if (status != NSS_STATUS_SUCCESS)
 692                         return(status);
 693                 status = winbindd_get_response(response);
 694                 count += 1;
 695         }
 696
 697         return status;
 698 }
 699
 700 NSS_STATUS winbindd_priv_request_response(int req_type,
 701                                           struct winbindd_request *request,
 702                                           struct winbindd_response *response)
 703 {
 704         NSS_STATUS status = NSS_STATUS_UNAVAIL;
 705         int count = 0;
 706
 707         while ((status == NSS_STATUS_UNAVAIL) && (count < 10)) {
 708                 status = winbindd_send_request(req_type, 1, request);
 709                 if (status != NSS_STATUS_SUCCESS)
 710                         return(status);
 711                 status = winbindd_get_response(response);
 712                 count += 1;
 713         }
 714
 715         return status;
 716 }