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    Copyright (C) Matthew Newton 2015
  10
  11
  12    This library is free software; you can redistribute it and/or
  13    modify it under the terms of the GNU Lesser General Public
  14    License as published by the Free Software Foundation; either
  15    version 3 of the License, or (at your option) any later version.
  16
  17    This library is distributed in the hope that it will be useful,
  18    but WITHOUT ANY WARRANTY; without even the implied warranty of
  19    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20    Library General Public License for more details.
  21
  22    You should have received a copy of the GNU Lesser General Public License
  23    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  24 */
  25
  26 #include "replace.h"
  27 #include "system/select.h"
  28 #include "winbind_client.h"
  29
  30 /* Global context */
  31
  32 struct winbindd_context {
  33         int winbindd_fd;        /* winbind file descriptor */
  34         bool is_privileged;     /* using the privileged socket? */
  35         pid_t our_pid;          /* calling process pid */
  36 };
  37
  38 static struct winbindd_context wb_global_ctx = {
  39         .winbindd_fd = -1,
  40         .is_privileged = false,
  41         .our_pid = 0
  42 };
  43
  44 /* Free a response structure */
  45
  46 void winbindd_free_response(struct winbindd_response *response)
  47 {
  48         /* Free any allocated extra_data */
  49
  50         if (response)
  51                 SAFE_FREE(response->extra_data.data);
  52 }
  53
  54 /* Initialise a request structure */
  55
  56 static void winbindd_init_request(struct winbindd_request *request,
  57                                   int request_type)
  58 {
  59         request->length = sizeof(struct winbindd_request);
  60
  61         request->cmd = (enum winbindd_cmd)request_type;
  62         request->pid = getpid();
  63
  64 }
  65
  66 /* Initialise a response structure */
  67
  68 static void init_response(struct winbindd_response *response)
  69 {
  70         /* Initialise return value */
  71
  72         response->result = WINBINDD_ERROR;
  73 }
  74
  75 /* Close established socket */
  76
  77 static void winbind_close_sock(struct winbindd_context *ctx)
  78 {
  79         if (!ctx) {
  80                 return;
  81         }
  82
  83         if (ctx->winbindd_fd != -1) {
  84                 close(ctx->winbindd_fd);
  85                 ctx->winbindd_fd = -1;
  86         }
  87 }
  88
  89 /* Destructor for global context to ensure fd is closed */
  90
  91 #if HAVE_DESTRUCTOR_ATTRIBUTE
  92 __attribute__((destructor))
  93 #endif
  94 static void winbind_destructor(void)
  95 {
  96         winbind_close_sock(&wb_global_ctx);
  97 }
  98
  99 #define CONNECT_TIMEOUT 30
 100
 101 /* Make sure socket handle isn't stdin, stdout or stderr */
 102 #define RECURSION_LIMIT 3
 103
 104 static int make_nonstd_fd_internals(int fd, int limit /* Recursion limiter */)
 105 {
 106         int new_fd;
 107         if (fd >= 0 && fd <= 2) {
 108 #ifdef F_DUPFD
 109                 if ((new_fd = fcntl(fd, F_DUPFD, 3)) == -1) {
 110                         return -1;
 111                 }
 112                 /* Paranoia */
 113                 if (new_fd < 3) {
 114                         close(new_fd);
 115                         return -1;
 116                 }
 117                 close(fd);
 118                 return new_fd;
 119 #else
 120                 if (limit <= 0)
 121                         return -1;
 122
 123                 new_fd = dup(fd);
 124                 if (new_fd == -1)
 125                         return -1;
 126
 127                 /* use the program stack to hold our list of FDs to close */
 128                 new_fd = make_nonstd_fd_internals(new_fd, limit - 1);
 129                 close(fd);
 130                 return new_fd;
 131 #endif
 132         }
 133         return fd;
 134 }
 135
 136 /****************************************************************************
 137  Set a fd into blocking/nonblocking mode. Uses POSIX O_NONBLOCK if available,
 138  else
 139  if SYSV use O_NDELAY
 140  if BSD use FNDELAY
 141  Set close on exec also.
 142 ****************************************************************************/
 143
 144 static int make_safe_fd(int fd)
 145 {
 146         int result, flags;
 147         int new_fd = make_nonstd_fd_internals(fd, RECURSION_LIMIT);
 148         if (new_fd == -1) {
 149                 close(fd);
 150                 return -1;
 151         }
 152
 153         /* Socket should be nonblocking. */
 154 #ifdef O_NONBLOCK
 155 #define FLAG_TO_SET O_NONBLOCK
 156 #else
 157 #ifdef SYSV
 158 #define FLAG_TO_SET O_NDELAY
 159 #else /* BSD */
 160 #define FLAG_TO_SET FNDELAY
 161 #endif
 162 #endif
 163
 164         if ((flags = fcntl(new_fd, F_GETFL)) == -1) {
 165                 close(new_fd);
 166                 return -1;
 167         }
 168
 169         flags |= FLAG_TO_SET;
 170         if (fcntl(new_fd, F_SETFL, flags) == -1) {
 171                 close(new_fd);
 172                 return -1;
 173         }
 174
 175 #undef FLAG_TO_SET
 176
 177         /* Socket should be closed on exec() */
 178 #ifdef FD_CLOEXEC
 179         result = flags = fcntl(new_fd, F_GETFD, 0);
 180         if (flags >= 0) {
 181                 flags |= FD_CLOEXEC;
 182                 result = fcntl( new_fd, F_SETFD, flags );
 183         }
 184         if (result < 0) {
 185                 close(new_fd);
 186                 return -1;
 187         }
 188 #endif
 189         return new_fd;
 190 }
 191
 192 /**
 193  * @internal
 194  *
 195  * @brief Check if we talk to the priviliged pipe which should be owned by root.
 196  *
 197  * This checks if we have uid_wrapper running and if this is the case it will
 198  * allow one to connect to the winbind privileged pipe even it is not owned by root.
 199  *
 200  * @param[in]  uid      The uid to check if we can safely talk to the pipe.
 201  *
 202  * @return              If we have access it returns true, else false.
 203  */
 204 static bool winbind_privileged_pipe_is_root(uid_t uid)
 205 {
 206         if (uid == 0) {
 207                 return true;
 208         }
 209
 210         if (uid_wrapper_enabled()) {
 211                 return true;
 212         }
 213
 214         return false;
 215 }
 216
 217 /* Connect to winbindd socket */
 218
 219 static int winbind_named_pipe_sock(const char *dir)
 220 {
 221         struct sockaddr_un sunaddr;
 222         struct stat st;
 223         int fd;
 224         int wait_time;
 225         int slept;
 226         int ret;
 227
 228         /* Check permissions on unix socket directory */
 229
 230         if (lstat(dir, &st) == -1) {
 231                 errno = ENOENT;
 232                 return -1;
 233         }
 234
 235         /*
 236          * This tells us that the pipe is owned by a privileged
 237          * process, as we will be sending passwords to it.
 238          */
 239         if (!S_ISDIR(st.st_mode) ||
 240             !winbind_privileged_pipe_is_root(st.st_uid)) {
 241                 errno = ENOENT;
 242                 return -1;
 243         }
 244
 245         /* Connect to socket */
 246
 247         sunaddr = (struct sockaddr_un) { .sun_family = AF_UNIX };
 248
 249         ret = snprintf(sunaddr.sun_path, sizeof(sunaddr.sun_path),
 250                        "%s/%s", dir, WINBINDD_SOCKET_NAME);
 251         if ((ret == -1) || (ret >= sizeof(sunaddr.sun_path))) {
 252                 errno = ENAMETOOLONG;
 253                 return -1;
 254         }
 255
 256         /* If socket file doesn't exist, don't bother trying to connect
 257            with retry.  This is an attempt to make the system usable when
 258            the winbindd daemon is not running. */
 259
 260         if (lstat(sunaddr.sun_path, &st) == -1) {
 261                 errno = ENOENT;
 262                 return -1;
 263         }
 264
 265         /* Check permissions on unix socket file */
 266
 267         /*
 268          * This tells us that the pipe is owned by a privileged
 269          * process, as we will be sending passwords to it.
 270          */
 271         if (!S_ISSOCK(st.st_mode) ||
 272             !winbind_privileged_pipe_is_root(st.st_uid)) {
 273                 errno = ENOENT;
 274                 return -1;
 275         }
 276
 277         /* Connect to socket */
 278
 279         if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
 280                 return -1;
 281         }
 282
 283         /* Set socket non-blocking and close on exec. */
 284
 285         if ((fd = make_safe_fd( fd)) == -1) {
 286                 return fd;
 287         }
 288
 289         for (wait_time = 0; connect(fd, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) == -1;
 290                         wait_time += slept) {
 291                 struct pollfd pfd;
 292                 int connect_errno = 0;
 293                 socklen_t errnosize;
 294
 295                 if (wait_time >= CONNECT_TIMEOUT)
 296                         goto error_out;
 297
 298                 switch (errno) {
 299                         case EINPROGRESS:
 300                                 pfd.fd = fd;
 301                                 pfd.events = POLLOUT;
 302
 303                                 ret = poll(&pfd, 1, (CONNECT_TIMEOUT - wait_time) * 1000);
 304
 305                                 if (ret > 0) {
 306                                         errnosize = sizeof(connect_errno);
 307
 308                                         ret = getsockopt(fd, SOL_SOCKET,
 309                                                         SO_ERROR, &connect_errno, &errnosize);
 310
 311                                         if (ret >= 0 && connect_errno == 0) {
 312                                                 /* Connect succeed */
 313                                                 goto out;
 314                                         }
 315                                 }
 316
 317                                 slept = CONNECT_TIMEOUT;
 318                                 break;
 319                         case EAGAIN:
 320                                 slept = rand() % 3 + 1;
 321                                 sleep(slept);
 322                                 break;
 323                         default:
 324                                 goto error_out;
 325                 }
 326
 327         }
 328
 329   out:
 330
 331         return fd;
 332
 333   error_out:
 334
 335         close(fd);
 336         return -1;
 337 }
 338
 339 static const char *winbindd_socket_dir(void)
 340 {
 341         if (nss_wrapper_enabled()) {
 342                 const char *env_dir;
 343
 344                 env_dir = getenv("SELFTEST_WINBINDD_SOCKET_DIR");
 345                 if (env_dir != NULL) {
 346                         return env_dir;
 347                 }
 348         }
 349
 350         return WINBINDD_SOCKET_DIR;
 351 }
 352
 353 /* Connect to winbindd socket */
 354
 355 static int winbind_open_pipe_sock(struct winbindd_context *ctx,
 356                                   int recursing, int need_priv)
 357 {
 358 #ifdef HAVE_UNIXSOCKET
 359         struct winbindd_request request;
 360         struct winbindd_response response;
 361
 362         ZERO_STRUCT(request);
 363         ZERO_STRUCT(response);
 364
 365         if (!ctx) {
 366                 return -1;
 367         }
 368
 369         if (ctx->our_pid != getpid()) {
 370                 winbind_close_sock(ctx);
 371                 ctx->our_pid = getpid();
 372         }
 373
 374         if ((need_priv != 0) && !ctx->is_privileged) {
 375                 winbind_close_sock(ctx);
 376         }
 377
 378         if (ctx->winbindd_fd != -1) {
 379                 return ctx->winbindd_fd;
 380         }
 381
 382         if (recursing) {
 383                 return -1;
 384         }
 385
 386         ctx->winbindd_fd = winbind_named_pipe_sock(winbindd_socket_dir());
 387
 388         if (ctx->winbindd_fd == -1) {
 389                 return -1;
 390         }
 391
 392         ctx->is_privileged = false;
 393
 394         /* version-check the socket */
 395
 396         request.wb_flags = WBFLAG_RECURSE;
 397         if ((winbindd_request_response(ctx, WINBINDD_INTERFACE_VERSION, &request,
 398                                        &response) != NSS_STATUS_SUCCESS) ||
 399             (response.data.interface_version != WINBIND_INTERFACE_VERSION)) {
 400                 winbind_close_sock(ctx);
 401                 return -1;
 402         }
 403
 404         if (need_priv == 0) {
 405                 return ctx->winbindd_fd;
 406         }
 407
 408         /* try and get priv pipe */
 409
 410         request.wb_flags = WBFLAG_RECURSE;
 411
 412         /* Note that response needs to be initialized to avoid
 413          * crashing on clean up after WINBINDD_PRIV_PIPE_DIR call failed
 414          * as interface version (from the first request) returned as a fstring,
 415          * thus response.extra_data.data will not be NULL even though
 416          * winbindd response did not write over it due to a failure */
 417         ZERO_STRUCT(response);
 418         if (winbindd_request_response(ctx, WINBINDD_PRIV_PIPE_DIR, &request,
 419                                       &response) == NSS_STATUS_SUCCESS) {
 420                 int fd;
 421                 fd = winbind_named_pipe_sock((char *)response.extra_data.data);
 422                 if (fd != -1) {
 423                         close(ctx->winbindd_fd);
 424                         ctx->winbindd_fd = fd;
 425                         ctx->is_privileged = true;
 426                 }
 427
 428                 SAFE_FREE(response.extra_data.data);
 429         }
 430
 431         if (!ctx->is_privileged) {
 432                 return -1;
 433         }
 434
 435         return ctx->winbindd_fd;
 436 #else
 437         return -1;
 438 #endif /* HAVE_UNIXSOCKET */
 439 }
 440
 441 /* Write data to winbindd socket */
 442
 443 static int winbind_write_sock(struct winbindd_context *ctx, void *buffer,
 444                               int count, int recursing, int need_priv)
 445 {
 446         int fd, result, nwritten;
 447
 448         /* Open connection to winbind daemon */
 449
 450  restart:
 451
 452         fd = winbind_open_pipe_sock(ctx, recursing, need_priv);
 453         if (fd == -1) {
 454                 errno = ENOENT;
 455                 return -1;
 456         }
 457
 458         /* Write data to socket */
 459
 460         nwritten = 0;
 461
 462         while(nwritten < count) {
 463                 struct pollfd pfd;
 464                 int ret;
 465
 466                 /* Catch pipe close on other end by checking if a read()
 467                    call would not block by calling poll(). */
 468
 469                 pfd.fd = fd;
 470                 pfd.events = POLLIN|POLLOUT|POLLHUP;
 471
 472                 ret = poll(&pfd, 1, -1);
 473                 if (ret == -1) {
 474                         winbind_close_sock(ctx);
 475                         return -1;                   /* poll error */
 476                 }
 477
 478                 /* Write should be OK if fd not available for reading */
 479
 480                 if ((ret == 1) && (pfd.revents & (POLLIN|POLLHUP|POLLERR))) {
 481
 482                         /* Pipe has closed on remote end */
 483
 484                         winbind_close_sock(ctx);
 485                         goto restart;
 486                 }
 487
 488                 /* Do the write */
 489
 490                 result = write(fd, (char *)buffer + nwritten,
 491                                count - nwritten);
 492
 493                 if ((result == -1) || (result == 0)) {
 494
 495                         /* Write failed */
 496
 497                         winbind_close_sock(ctx);
 498                         return -1;
 499                 }
 500
 501                 nwritten += result;
 502         }
 503
 504         return nwritten;
 505 }
 506
 507 /* Read data from winbindd socket */
 508
 509 static int winbind_read_sock(struct winbindd_context *ctx,
 510                              void *buffer, int count)
 511 {
 512         int fd;
 513         int nread = 0;
 514         int total_time = 0;
 515
 516         fd = winbind_open_pipe_sock(ctx, false, false);
 517         if (fd == -1) {
 518                 return -1;
 519         }
 520
 521         /* Read data from socket */
 522         while(nread < count) {
 523                 struct pollfd pfd;
 524                 int ret;
 525
 526                 /* Catch pipe close on other end by checking if a read()
 527                    call would not block by calling poll(). */
 528
 529                 pfd.fd = fd;
 530                 pfd.events = POLLIN|POLLHUP;
 531
 532                 /* Wait for 5 seconds for a reply. May need to parameterise this... */
 533
 534                 ret = poll(&pfd, 1, 5000);
 535                 if (ret == -1) {
 536                         winbind_close_sock(ctx);
 537                         return -1;                   /* poll error */
 538                 }
 539
 540                 if (ret == 0) {
 541                         /* Not ready for read yet... */
 542                         if (total_time >= 300) {
 543                                 /* Timeout */
 544                                 winbind_close_sock(ctx);
 545                                 return -1;
 546                         }
 547                         total_time += 5;
 548                         continue;
 549                 }
 550
 551                 if ((ret == 1) && (pfd.revents & (POLLIN|POLLHUP|POLLERR))) {
 552
 553                         /* Do the Read */
 554
 555                         int result = read(fd, (char *)buffer + nread,
 556                               count - nread);
 557
 558                         if ((result == -1) || (result == 0)) {
 559
 560                                 /* Read failed.  I think the only useful thing we
 561                                    can do here is just return -1 and fail since the
 562                                    transaction has failed half way through. */
 563
 564                                 winbind_close_sock(ctx);
 565                                 return -1;
 566                         }
 567
 568                         nread += result;
 569
 570                 }
 571         }
 572
 573         return nread;
 574 }
 575
 576 /* Read reply */
 577
 578 static int winbindd_read_reply(struct winbindd_context *ctx,
 579                                struct winbindd_response *response)
 580 {
 581         int result1, result2 = 0;
 582
 583         if (!response) {
 584                 return -1;
 585         }
 586
 587         /* Read fixed length response */
 588
 589         result1 = winbind_read_sock(ctx, response,
 590                                     sizeof(struct winbindd_response));
 591
 592         /* We actually send the pointer value of the extra_data field from
 593            the server.  This has no meaning in the client's address space
 594            so we clear it out. */
 595
 596         response->extra_data.data = NULL;
 597
 598         if (result1 == -1) {
 599                 return -1;
 600         }
 601
 602         if (response->length < sizeof(struct winbindd_response)) {
 603                 return -1;
 604         }
 605
 606         /* Read variable length response */
 607
 608         if (response->length > sizeof(struct winbindd_response)) {
 609                 int extra_data_len = response->length -
 610                         sizeof(struct winbindd_response);
 611
 612                 /* Mallocate memory for extra data */
 613
 614                 if (!(response->extra_data.data = malloc(extra_data_len))) {
 615                         return -1;
 616                 }
 617
 618                 result2 = winbind_read_sock(ctx, response->extra_data.data,
 619                                             extra_data_len);
 620                 if (result2 == -1) {
 621                         winbindd_free_response(response);
 622                         return -1;
 623                 }
 624         }
 625
 626         /* Return total amount of data read */
 627
 628         return result1 + result2;
 629 }
 630
 631 /*
 632  * send simple types of requests
 633  */
 634
 635 static NSS_STATUS winbindd_send_request(
 636         struct winbindd_context *ctx,
 637         int req_type,
 638         int need_priv,
 639         struct winbindd_request *request)
 640 {
 641         struct winbindd_request lrequest;
 642
 643         /* Check for our tricky environment variable */
 644
 645         if (winbind_env_set()) {
 646                 return NSS_STATUS_NOTFOUND;
 647         }
 648
 649         if (!request) {
 650                 ZERO_STRUCT(lrequest);
 651                 request = &lrequest;
 652         }
 653
 654         /* Fill in request and send down pipe */
 655
 656         winbindd_init_request(request, req_type);
 657
 658         if (winbind_write_sock(ctx, request, sizeof(*request),
 659                                request->wb_flags & WBFLAG_RECURSE,
 660                                need_priv) == -1)
 661         {
 662                 /* Set ENOENT for consistency.  Required by some apps */
 663                 errno = ENOENT;
 664
 665                 return NSS_STATUS_UNAVAIL;
 666         }
 667
 668         if ((request->extra_len != 0) &&
 669             (winbind_write_sock(ctx, request->extra_data.data,
 670                                 request->extra_len,
 671                                 request->wb_flags & WBFLAG_RECURSE,
 672                                 need_priv) == -1))
 673         {
 674                 /* Set ENOENT for consistency.  Required by some apps */
 675                 errno = ENOENT;
 676
 677                 return NSS_STATUS_UNAVAIL;
 678         }
 679
 680         return NSS_STATUS_SUCCESS;
 681 }
 682
 683 /*
 684  * Get results from winbindd request
 685  */
 686
 687 static NSS_STATUS winbindd_get_response(struct winbindd_context *ctx,
 688                                         struct winbindd_response *response)
 689 {
 690         struct winbindd_response lresponse;
 691
 692         if (!response) {
 693                 ZERO_STRUCT(lresponse);
 694                 response = &lresponse;
 695         }
 696
 697         init_response(response);
 698
 699         /* Wait for reply */
 700         if (winbindd_read_reply(ctx, response) == -1) {
 701                 /* Set ENOENT for consistency.  Required by some apps */
 702                 errno = ENOENT;
 703
 704                 return NSS_STATUS_UNAVAIL;
 705         }
 706
 707         /* Throw away extra data if client didn't request it */
 708         if (response == &lresponse) {
 709                 winbindd_free_response(response);
 710         }
 711
 712         /* Copy reply data from socket */
 713         if (response->result != WINBINDD_OK) {
 714                 return NSS_STATUS_NOTFOUND;
 715         }
 716
 717         return NSS_STATUS_SUCCESS;
 718 }
 719
 720 /* Handle simple types of requests */
 721
 722 NSS_STATUS winbindd_request_response(struct winbindd_context *ctx,
 723                                      int req_type,
 724                                      struct winbindd_request *request,
 725                                      struct winbindd_response *response)
 726 {
 727         NSS_STATUS status = NSS_STATUS_UNAVAIL;
 728
 729         if (ctx == NULL) {
 730                 ctx = &wb_global_ctx;
 731         }
 732
 733         status = winbindd_send_request(ctx, req_type, 0, request);
 734         if (status != NSS_STATUS_SUCCESS)
 735                 return (status);
 736         status = winbindd_get_response(ctx, response);
 737
 738         return status;
 739 }
 740
 741 NSS_STATUS winbindd_priv_request_response(struct winbindd_context *ctx,
 742                                           int req_type,
 743                                           struct winbindd_request *request,
 744                                           struct winbindd_response *response)
 745 {
 746         NSS_STATUS status = NSS_STATUS_UNAVAIL;
 747
 748         if (ctx == NULL) {
 749                 ctx = &wb_global_ctx;
 750         }
 751
 752         status = winbindd_send_request(ctx, req_type, 1, request);
 753         if (status != NSS_STATUS_SUCCESS)
 754                 return (status);
 755         status = winbindd_get_response(ctx, response);
 756
 757         return status;
 758 }
 759
 760 /* Create and free winbindd context */
 761
 762 struct winbindd_context *winbindd_ctx_create(void)
 763 {
 764         struct winbindd_context *ctx;
 765
 766         ctx = calloc(1, sizeof(struct winbindd_context));
 767
 768         if (!ctx) {
 769                 return NULL;
 770         }
 771
 772         ctx->winbindd_fd = -1;
 773
 774         return ctx;
 775 }
 776
 777 void winbindd_ctx_free(struct winbindd_context *ctx)
 778 {
 779         winbind_close_sock(ctx);
 780         free(ctx);
 781 }