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 = 0,
  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_FUNCTION_ATTRIBUTE_DESTRUCTOR
  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 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         char *path = NULL;
 224         int fd;
 225         int wait_time;
 226         int slept;
 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         if (asprintf(&path, "%s/%s", dir, WINBINDD_SOCKET_NAME) < 0) {
 248                 return -1;
 249         }
 250
 251         ZERO_STRUCT(sunaddr);
 252         sunaddr.sun_family = AF_UNIX;
 253         strncpy(sunaddr.sun_path, path, sizeof(sunaddr.sun_path) - 1);
 254
 255         /* If socket file doesn't exist, don't bother trying to connect
 256            with retry.  This is an attempt to make the system usable when
 257            the winbindd daemon is not running. */
 258
 259         if (lstat(path, &st) == -1) {
 260                 errno = ENOENT;
 261                 SAFE_FREE(path);
 262                 return -1;
 263         }
 264
 265         SAFE_FREE(path);
 266         /* Check permissions on unix socket file */
 267
 268         /*
 269          * This tells us that the pipe is owned by a privileged
 270          * process, as we will be sending passwords to it.
 271          */
 272         if (!S_ISSOCK(st.st_mode) ||
 273             !winbind_privileged_pipe_is_root(st.st_uid)) {
 274                 errno = ENOENT;
 275                 return -1;
 276         }
 277
 278         /* Connect to socket */
 279
 280         if ((fd = socket(AF_UNIX, SOCK_STREAM, 0)) == -1) {
 281                 return -1;
 282         }
 283
 284         /* Set socket non-blocking and close on exec. */
 285
 286         if ((fd = make_safe_fd( fd)) == -1) {
 287                 return fd;
 288         }
 289
 290         for (wait_time = 0; connect(fd, (struct sockaddr *)&sunaddr, sizeof(sunaddr)) == -1;
 291                         wait_time += slept) {
 292                 struct pollfd pfd;
 293                 int ret;
 294                 int connect_errno = 0;
 295                 socklen_t errnosize;
 296
 297                 if (wait_time >= CONNECT_TIMEOUT)
 298                         goto error_out;
 299
 300                 switch (errno) {
 301                         case EINPROGRESS:
 302                                 pfd.fd = fd;
 303                                 pfd.events = POLLOUT;
 304
 305                                 ret = poll(&pfd, 1, (CONNECT_TIMEOUT - wait_time) * 1000);
 306
 307                                 if (ret > 0) {
 308                                         errnosize = sizeof(connect_errno);
 309
 310                                         ret = getsockopt(fd, SOL_SOCKET,
 311                                                         SO_ERROR, &connect_errno, &errnosize);
 312
 313                                         if (ret >= 0 && connect_errno == 0) {
 314                                                 /* Connect succeed */
 315                                                 goto out;
 316                                         }
 317                                 }
 318
 319                                 slept = CONNECT_TIMEOUT;
 320                                 break;
 321                         case EAGAIN:
 322                                 slept = rand() % 3 + 1;
 323                                 sleep(slept);
 324                                 break;
 325                         default:
 326                                 goto error_out;
 327                 }
 328
 329         }
 330
 331   out:
 332
 333         return fd;
 334
 335   error_out:
 336
 337         close(fd);
 338         return -1;
 339 }
 340
 341 static const char *winbindd_socket_dir(void)
 342 {
 343         if (nss_wrapper_enabled()) {
 344                 const char *env_dir;
 345
 346                 env_dir = getenv("SELFTEST_WINBINDD_SOCKET_DIR");
 347                 if (env_dir != NULL) {
 348                         return env_dir;
 349                 }
 350         }
 351
 352         return WINBINDD_SOCKET_DIR;
 353 }
 354
 355 /* Connect to winbindd socket */
 356
 357 static int winbind_open_pipe_sock(struct winbindd_context *ctx,
 358                                   int recursing, int need_priv)
 359 {
 360 #ifdef HAVE_UNIXSOCKET
 361         struct winbindd_request request;
 362         struct winbindd_response response;
 363
 364         ZERO_STRUCT(request);
 365         ZERO_STRUCT(response);
 366
 367         if (!ctx) {
 368                 return -1;
 369         }
 370
 371         if (ctx->our_pid != getpid()) {
 372                 winbind_close_sock(ctx);
 373                 ctx->our_pid = getpid();
 374         }
 375
 376         if ((need_priv != 0) && (ctx->is_privileged == 0)) {
 377                 winbind_close_sock(ctx);
 378         }
 379
 380         if (ctx->winbindd_fd != -1) {
 381                 return ctx->winbindd_fd;
 382         }
 383
 384         if (recursing) {
 385                 return -1;
 386         }
 387
 388         ctx->winbindd_fd = winbind_named_pipe_sock(winbindd_socket_dir());
 389
 390         if (ctx->winbindd_fd == -1) {
 391                 return -1;
 392         }
 393
 394         ctx->is_privileged = 0;
 395
 396         /* version-check the socket */
 397
 398         request.wb_flags = WBFLAG_RECURSE;
 399         if ((winbindd_request_response(ctx, WINBINDD_INTERFACE_VERSION, &request,
 400                                        &response) != NSS_STATUS_SUCCESS) ||
 401             (response.data.interface_version != WINBIND_INTERFACE_VERSION)) {
 402                 winbind_close_sock(ctx);
 403                 return -1;
 404         }
 405
 406         /* try and get priv pipe */
 407
 408         request.wb_flags = WBFLAG_RECURSE;
 409
 410         /* Note that response needs to be initialized to avoid
 411          * crashing on clean up after WINBINDD_PRIV_PIPE_DIR call failed
 412          * as interface version (from the first request) returned as a fstring,
 413          * thus response.extra_data.data will not be NULL even though
 414          * winbindd response did not write over it due to a failure */
 415         ZERO_STRUCT(response);
 416         if (winbindd_request_response(ctx, WINBINDD_PRIV_PIPE_DIR, &request,
 417                                       &response) == NSS_STATUS_SUCCESS) {
 418                 int fd;
 419                 fd = winbind_named_pipe_sock((char *)response.extra_data.data);
 420                 if (fd != -1) {
 421                         close(ctx->winbindd_fd);
 422                         ctx->winbindd_fd = fd;
 423                         ctx->is_privileged = 1;
 424                 }
 425         }
 426
 427         if ((need_priv != 0) && (ctx->is_privileged == 0)) {
 428                 return -1;
 429         }
 430
 431         SAFE_FREE(response.extra_data.data);
 432
 433         return ctx->winbindd_fd;
 434 #else
 435         return -1;
 436 #endif /* HAVE_UNIXSOCKET */
 437 }
 438
 439 /* Write data to winbindd socket */
 440
 441 static int winbind_write_sock(struct winbindd_context *ctx, void *buffer,
 442                               int count, int recursing, int need_priv)
 443 {
 444         int fd, result, nwritten;
 445
 446         /* Open connection to winbind daemon */
 447
 448  restart:
 449
 450         fd = winbind_open_pipe_sock(ctx, recursing, need_priv);
 451         if (fd == -1) {
 452                 errno = ENOENT;
 453                 return -1;
 454         }
 455
 456         /* Write data to socket */
 457
 458         nwritten = 0;
 459
 460         while(nwritten < count) {
 461                 struct pollfd pfd;
 462                 int ret;
 463
 464                 /* Catch pipe close on other end by checking if a read()
 465                    call would not block by calling poll(). */
 466
 467                 pfd.fd = fd;
 468                 pfd.events = POLLIN|POLLOUT|POLLHUP;
 469
 470                 ret = poll(&pfd, 1, -1);
 471                 if (ret == -1) {
 472                         winbind_close_sock(ctx);
 473                         return -1;                   /* poll error */
 474                 }
 475
 476                 /* Write should be OK if fd not available for reading */
 477
 478                 if ((ret == 1) && (pfd.revents & (POLLIN|POLLHUP|POLLERR))) {
 479
 480                         /* Pipe has closed on remote end */
 481
 482                         winbind_close_sock(ctx);
 483                         goto restart;
 484                 }
 485
 486                 /* Do the write */
 487
 488                 result = write(fd, (char *)buffer + nwritten,
 489                                count - nwritten);
 490
 491                 if ((result == -1) || (result == 0)) {
 492
 493                         /* Write failed */
 494
 495                         winbind_close_sock(ctx);
 496                         return -1;
 497                 }
 498
 499                 nwritten += result;
 500         }
 501
 502         return nwritten;
 503 }
 504
 505 /* Read data from winbindd socket */
 506
 507 static int winbind_read_sock(struct winbindd_context *ctx,
 508                              void *buffer, int count)
 509 {
 510         int fd;
 511         int nread = 0;
 512         int total_time = 0;
 513
 514         fd = winbind_open_pipe_sock(ctx, false, false);
 515         if (fd == -1) {
 516                 return -1;
 517         }
 518
 519         /* Read data from socket */
 520         while(nread < count) {
 521                 struct pollfd pfd;
 522                 int ret;
 523
 524                 /* Catch pipe close on other end by checking if a read()
 525                    call would not block by calling poll(). */
 526
 527                 pfd.fd = fd;
 528                 pfd.events = POLLIN|POLLHUP;
 529
 530                 /* Wait for 5 seconds for a reply. May need to parameterise this... */
 531
 532                 ret = poll(&pfd, 1, 5000);
 533                 if (ret == -1) {
 534                         winbind_close_sock(ctx);
 535                         return -1;                   /* poll error */
 536                 }
 537
 538                 if (ret == 0) {
 539                         /* Not ready for read yet... */
 540                         if (total_time >= 30) {
 541                                 /* Timeout */
 542                                 winbind_close_sock(ctx);
 543                                 return -1;
 544                         }
 545                         total_time += 5;
 546                         continue;
 547                 }
 548
 549                 if ((ret == 1) && (pfd.revents & (POLLIN|POLLHUP|POLLERR))) {
 550
 551                         /* Do the Read */
 552
 553                         int result = read(fd, (char *)buffer + nread,
 554                               count - nread);
 555
 556                         if ((result == -1) || (result == 0)) {
 557
 558                                 /* Read failed.  I think the only useful thing we
 559                                    can do here is just return -1 and fail since the
 560                                    transaction has failed half way through. */
 561
 562                                 winbind_close_sock(ctx);
 563                                 return -1;
 564                         }
 565
 566                         nread += result;
 567
 568                 }
 569         }
 570
 571         return nread;
 572 }
 573
 574 /* Read reply */
 575
 576 static int winbindd_read_reply(struct winbindd_context *ctx,
 577                                struct winbindd_response *response)
 578 {
 579         int result1, result2 = 0;
 580
 581         if (!response) {
 582                 return -1;
 583         }
 584
 585         /* Read fixed length response */
 586
 587         result1 = winbind_read_sock(ctx, response,
 588                                     sizeof(struct winbindd_response));
 589
 590         /* We actually send the pointer value of the extra_data field from
 591            the server.  This has no meaning in the client's address space
 592            so we clear it out. */
 593
 594         response->extra_data.data = NULL;
 595
 596         if (result1 == -1) {
 597                 return -1;
 598         }
 599
 600         if (response->length < sizeof(struct winbindd_response)) {
 601                 return -1;
 602         }
 603
 604         /* Read variable length response */
 605
 606         if (response->length > sizeof(struct winbindd_response)) {
 607                 int extra_data_len = response->length -
 608                         sizeof(struct winbindd_response);
 609
 610                 /* Mallocate memory for extra data */
 611
 612                 if (!(response->extra_data.data = malloc(extra_data_len))) {
 613                         return -1;
 614                 }
 615
 616                 result2 = winbind_read_sock(ctx, response->extra_data.data,
 617                                             extra_data_len);
 618                 if (result2 == -1) {
 619                         winbindd_free_response(response);
 620                         return -1;
 621                 }
 622         }
 623
 624         /* Return total amount of data read */
 625
 626         return result1 + result2;
 627 }
 628
 629 /*
 630  * send simple types of requests
 631  */
 632
 633 NSS_STATUS winbindd_send_request(struct winbindd_context *ctx,
 634                                  int req_type, int need_priv,
 635                                  struct winbindd_request *request)
 636 {
 637         struct winbindd_request lrequest;
 638
 639         /* Check for our tricky environment variable */
 640
 641         if (winbind_env_set()) {
 642                 return NSS_STATUS_NOTFOUND;
 643         }
 644
 645         if (!request) {
 646                 ZERO_STRUCT(lrequest);
 647                 request = &lrequest;
 648         }
 649
 650         /* Fill in request and send down pipe */
 651
 652         winbindd_init_request(request, req_type);
 653
 654         if (winbind_write_sock(ctx, request, sizeof(*request),
 655                                request->wb_flags & WBFLAG_RECURSE,
 656                                need_priv) == -1)
 657         {
 658                 /* Set ENOENT for consistency.  Required by some apps */
 659                 errno = ENOENT;
 660
 661                 return NSS_STATUS_UNAVAIL;
 662         }
 663
 664         if ((request->extra_len != 0) &&
 665             (winbind_write_sock(ctx, request->extra_data.data,
 666                                 request->extra_len,
 667                                 request->wb_flags & WBFLAG_RECURSE,
 668                                 need_priv) == -1))
 669         {
 670                 /* Set ENOENT for consistency.  Required by some apps */
 671                 errno = ENOENT;
 672
 673                 return NSS_STATUS_UNAVAIL;
 674         }
 675
 676         return NSS_STATUS_SUCCESS;
 677 }
 678
 679 /*
 680  * Get results from winbindd request
 681  */
 682
 683 NSS_STATUS winbindd_get_response(struct winbindd_context *ctx,
 684                                  struct winbindd_response *response)
 685 {
 686         struct winbindd_response lresponse;
 687
 688         if (!response) {
 689                 ZERO_STRUCT(lresponse);
 690                 response = &lresponse;
 691         }
 692
 693         init_response(response);
 694
 695         /* Wait for reply */
 696         if (winbindd_read_reply(ctx, response) == -1) {
 697                 /* Set ENOENT for consistency.  Required by some apps */
 698                 errno = ENOENT;
 699
 700                 return NSS_STATUS_UNAVAIL;
 701         }
 702
 703         /* Throw away extra data if client didn't request it */
 704         if (response == &lresponse) {
 705                 winbindd_free_response(response);
 706         }
 707
 708         /* Copy reply data from socket */
 709         if (response->result != WINBINDD_OK) {
 710                 return NSS_STATUS_NOTFOUND;
 711         }
 712
 713         return NSS_STATUS_SUCCESS;
 714 }
 715
 716 /* Handle simple types of requests */
 717
 718 NSS_STATUS winbindd_request_response(struct winbindd_context *ctx,
 719                                      int req_type,
 720                                      struct winbindd_request *request,
 721                                      struct winbindd_response *response)
 722 {
 723         NSS_STATUS status = NSS_STATUS_UNAVAIL;
 724         int count = 0;
 725         struct winbindd_context *wb_ctx = ctx;
 726
 727         if (ctx == NULL) {
 728                 wb_ctx = &wb_global_ctx;
 729         }
 730
 731         while ((status == NSS_STATUS_UNAVAIL) && (count < 10)) {
 732                 status = winbindd_send_request(wb_ctx, req_type, 0, request);
 733                 if (status != NSS_STATUS_SUCCESS)
 734                         return(status);
 735                 status = winbindd_get_response(wb_ctx, response);
 736                 count += 1;
 737         }
 738
 739         return status;
 740 }
 741
 742 NSS_STATUS winbindd_priv_request_response(struct winbindd_context *ctx,
 743                                           int req_type,
 744                                           struct winbindd_request *request,
 745                                           struct winbindd_response *response)
 746 {
 747         NSS_STATUS status = NSS_STATUS_UNAVAIL;
 748         int count = 0;
 749         struct winbindd_context *wb_ctx = ctx;
 750
 751         if (ctx == NULL) {
 752                 wb_ctx = &wb_global_ctx;
 753         }
 754
 755         while ((status == NSS_STATUS_UNAVAIL) && (count < 10)) {
 756                 status = winbindd_send_request(wb_ctx, req_type, 1, request);
 757                 if (status != NSS_STATUS_SUCCESS)
 758                         return(status);
 759                 status = winbindd_get_response(wb_ctx, response);
 760                 count += 1;
 761         }
 762
 763         return status;
 764 }
 765
 766 /* Create and free winbindd context */
 767
 768 struct winbindd_context *winbindd_ctx_create(void)
 769 {
 770         struct winbindd_context *ctx;
 771
 772         ctx = calloc(1, sizeof(struct winbindd_context));
 773
 774         if (!ctx) {
 775                 return NULL;
 776         }
 777
 778         ctx->winbindd_fd = -1;
 779
 780         return ctx;
 781 }
 782
 783 void winbindd_ctx_free(struct winbindd_context *ctx)
 784 {
 785         winbind_close_sock(ctx);
 786         free(ctx);
 787 }