src/common/runas.c

   1 /*
   2  * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
   3  *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License, version 2 only,
   7  * as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #define _LGPL_SOURCE
  20 #include <errno.h>
  21 #include <limits.h>
  22 #include <stdio.h>
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <sys/wait.h>
  26 #include <sys/types.h>
  27 #include <sys/stat.h>
  28 #include <unistd.h>
  29 #include <fcntl.h>
  30 #include <sched.h>
  31 #include <signal.h>
  32 #include <assert.h>
  33 #include <signal.h>
  34
  35 #include <common/lttng-kernel.h>
  36 #include <common/common.h>
  37 #include <common/utils.h>
  38 #include <common/compat/getenv.h>
  39 #include <common/compat/prctl.h>
  40 #include <common/unix.h>
  41 #include <common/defaults.h>
  42 #include <common/lttng-elf.h>
  43
  44 #include <lttng/constant.h>
  45
  46 #include "runas.h"
  47
  48 struct run_as_data;
  49 struct run_as_ret;
  50 typedef int (*run_as_fct)(struct run_as_data *data, struct run_as_ret *ret_value);
  51
  52 struct run_as_mkdir_data {
  53         char path[PATH_MAX];
  54         mode_t mode;
  55 };
  56
  57 struct run_as_open_data {
  58         char path[PATH_MAX];
  59         int flags;
  60         mode_t mode;
  61 };
  62
  63 struct run_as_unlink_data {
  64         char path[PATH_MAX];
  65 };
  66
  67 struct run_as_rmdir_recursive_data {
  68         char path[PATH_MAX];
  69 };
  70
  71 struct run_as_extract_elf_symbol_offset_data {
  72         char function[LTTNG_SYMBOL_NAME_LEN];
  73 };
  74
  75 struct run_as_extract_sdt_probe_offsets_data {
  76         char probe_name[LTTNG_SYMBOL_NAME_LEN];
  77         char provider_name[LTTNG_SYMBOL_NAME_LEN];
  78 };
  79
  80 struct run_as_mkdir_ret {
  81         int ret;
  82 };
  83
  84 struct run_as_open_ret {
  85         int ret;
  86 };
  87
  88 struct run_as_unlink_ret {
  89         int ret;
  90 };
  91
  92 struct run_as_rmdir_recursive_ret {
  93         int ret;
  94 };
  95
  96 struct run_as_extract_elf_symbol_offset_ret {
  97         uint64_t offset;
  98 };
  99
 100 struct run_as_extract_sdt_probe_offsets_ret {
 101         uint32_t num_offset;
 102         uint64_t offsets[LTTNG_KERNEL_MAX_UPROBE_NUM];
 103 };
 104
 105 enum run_as_cmd {
 106         RUN_AS_MKDIR,
 107         RUN_AS_OPEN,
 108         RUN_AS_UNLINK,
 109         RUN_AS_RMDIR_RECURSIVE,
 110         RUN_AS_MKDIR_RECURSIVE,
 111         RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET,
 112         RUN_AS_EXTRACT_SDT_PROBE_OFFSETS,
 113 };
 114
 115 struct run_as_data {
 116         enum run_as_cmd cmd;
 117         int fd;
 118         union {
 119                 struct run_as_mkdir_data mkdir;
 120                 struct run_as_open_data open;
 121                 struct run_as_unlink_data unlink;
 122                 struct run_as_rmdir_recursive_data rmdir_recursive;
 123                 struct run_as_extract_elf_symbol_offset_data extract_elf_symbol_offset;
 124                 struct run_as_extract_sdt_probe_offsets_data extract_sdt_probe_offsets;
 125         } u;
 126         uid_t uid;
 127         gid_t gid;
 128 };
 129
 130 /*
 131  * The run_as_ret structure holds the returned value and status of the command.
 132  *
 133  * The `u` union field holds the return value of the command; in most cases it
 134  * represents the success or the failure of the command. In more complex
 135  * commands, it holds a computed value.
 136  *
 137  * The _errno field is the errno recorded after the execution of the command.
 138  *
 139  * The _error fields is used the signify that return status of the command. For
 140  * simple commands returning `int` the _error field will be the same as the
 141  * ret_int field. In complex commands, it signify the success or failure of the
 142  * command.
 143  *
 144  */
 145 struct run_as_ret {
 146         int fd;
 147         union {
 148                 struct run_as_mkdir_ret mkdir;
 149                 struct run_as_open_ret open;
 150                 struct run_as_unlink_ret unlink;
 151                 struct run_as_rmdir_recursive_ret rmdir_recursive;
 152                 struct run_as_extract_elf_symbol_offset_ret extract_elf_symbol_offset;
 153                 struct run_as_extract_sdt_probe_offsets_ret extract_sdt_probe_offsets;
 154         } u;
 155         int _errno;
 156         bool _error;
 157 };
 158
 159 struct run_as_worker {
 160         pid_t pid;      /* Worker PID. */
 161         int sockpair[2];
 162         char *procname;
 163 };
 164
 165 /* Single global worker per process (for now). */
 166 static struct run_as_worker *global_worker;
 167 /* Lock protecting the worker. */
 168 static pthread_mutex_t worker_lock = PTHREAD_MUTEX_INITIALIZER;
 169
 170 #ifdef VALGRIND
 171 static
 172 int use_clone(void)
 173 {
 174         return 0;
 175 }
 176 #else
 177 static
 178 int use_clone(void)
 179 {
 180         return !lttng_secure_getenv("LTTNG_DEBUG_NOCLONE");
 181 }
 182 #endif
 183
 184 LTTNG_HIDDEN
 185 int _utils_mkdir_recursive_unsafe(const char *path, mode_t mode);
 186
 187 /*
 188  * Create recursively directory using the FULL path.
 189  */
 190 static
 191 int _mkdir_recursive(struct run_as_data *data, struct run_as_ret *ret_value)
 192 {
 193         const char *path;
 194         mode_t mode;
 195
 196         path = data->u.mkdir.path;
 197         mode = data->u.mkdir.mode;
 198
 199         /* Safe to call as we have transitioned to the requested uid/gid. */
 200         ret_value->u.mkdir.ret = _utils_mkdir_recursive_unsafe(path, mode);
 201         ret_value->_errno = errno;
 202         ret_value->_error = (ret_value->u.mkdir.ret) ? true : false;
 203         return ret_value->u.mkdir.ret;
 204 }
 205
 206 static
 207 int _mkdir(struct run_as_data *data, struct run_as_ret *ret_value)
 208 {
 209         ret_value->u.mkdir.ret = mkdir(data->u.mkdir.path, data->u.mkdir.mode);
 210         ret_value->_errno = errno;
 211         ret_value->_error = (ret_value->u.mkdir.ret) ? true : false;
 212         return ret_value->u.mkdir.ret;
 213 }
 214
 215 static
 216 int _open(struct run_as_data *data, struct run_as_ret *ret_value)
 217 {
 218         ret_value->u.open.ret = open(data->u.open.path, data->u.open.flags, data->u.open.mode);
 219         ret_value->fd = ret_value->u.open.ret;
 220         ret_value->_errno = errno;
 221         ret_value->_error = (ret_value->u.open.ret) ? true : false;
 222         return ret_value->u.open.ret;
 223 }
 224
 225 static
 226 int _unlink(struct run_as_data *data, struct run_as_ret *ret_value)
 227 {
 228         ret_value->u.unlink.ret = unlink(data->u.unlink.path);
 229         ret_value->_errno = errno;
 230         ret_value->_error = (ret_value->u.unlink.ret) ? true : false;
 231         return ret_value->u.unlink.ret;
 232 }
 233
 234 static
 235 int _rmdir_recursive(struct run_as_data *data, struct run_as_ret *ret_value)
 236 {
 237         ret_value->u.rmdir_recursive.ret = utils_recursive_rmdir(data->u.rmdir_recursive.path);
 238         ret_value->_errno = errno;
 239         ret_value->_error = (ret_value->u.rmdir_recursive.ret) ? true : false;
 240         return ret_value->u.rmdir_recursive.ret;
 241 }
 242
 243 static
 244 int _extract_elf_symbol_offset(struct run_as_data *data,
 245                 struct run_as_ret *ret_value)
 246 {
 247         int ret = 0;
 248         ret_value->_error = false;
 249
 250         ret = lttng_elf_get_symbol_offset(data->fd,
 251                          data->u.extract_elf_symbol_offset.function,
 252                          &ret_value->u.extract_elf_symbol_offset.offset);
 253         if (ret) {
 254                 DBG("Failed to extract ELF function offset");
 255                 ret_value->_error = true;
 256         }
 257
 258         return ret;
 259 }
 260
 261 static
 262 int _extract_sdt_probe_offsets(struct run_as_data *data,
 263                 struct run_as_ret *ret_value)
 264 {
 265         int ret = 0;
 266         uint64_t *offsets = NULL;
 267         uint32_t num_offset;
 268
 269         ret_value->_error = false;
 270
 271         /* On success, this call allocates the offsets paramater. */
 272         ret = lttng_elf_get_sdt_probe_offsets(data->fd,
 273                         data->u.extract_sdt_probe_offsets.provider_name,
 274                         data->u.extract_sdt_probe_offsets.probe_name,
 275                         &offsets, &num_offset);
 276
 277         if (ret) {
 278                 DBG("Failed to extract SDT probe offsets");
 279                 ret_value->_error = true;
 280                 goto end;
 281         }
 282
 283         if (num_offset <= 0 || num_offset > LTTNG_KERNEL_MAX_UPROBE_NUM) {
 284                 DBG("Wrong number of probes.");
 285                 ret = -1;
 286                 ret_value->_error = true;
 287                 goto free_offset;
 288         }
 289
 290         /* Copy the content of the offsets array to the ret struct. */
 291         memcpy(ret_value->u.extract_sdt_probe_offsets.offsets,
 292                         offsets, num_offset * sizeof(uint64_t));
 293
 294         ret_value->u.extract_sdt_probe_offsets.num_offset = num_offset;
 295
 296 free_offset:
 297         free(offsets);
 298 end:
 299         return ret;
 300 }
 301
 302 static
 303 run_as_fct run_as_enum_to_fct(enum run_as_cmd cmd)
 304 {
 305         switch (cmd) {
 306         case RUN_AS_MKDIR:
 307                 return _mkdir;
 308         case RUN_AS_OPEN:
 309                 return _open;
 310         case RUN_AS_UNLINK:
 311                 return _unlink;
 312         case RUN_AS_RMDIR_RECURSIVE:
 313                 return _rmdir_recursive;
 314         case RUN_AS_MKDIR_RECURSIVE:
 315                 return _mkdir_recursive;
 316         case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET:
 317                 return _extract_elf_symbol_offset;
 318         case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS:
 319                 return _extract_sdt_probe_offsets;
 320         default:
 321                 ERR("Unknown command %d", (int) cmd);
 322                 return NULL;
 323         }
 324 }
 325
 326 static
 327 int do_send_fd(int sock, int fd)
 328 {
 329         ssize_t len;
 330
 331         if (fd < 0) {
 332                 ERR("Invalid file description");
 333                 return 0;
 334         }
 335
 336         len = lttcomm_send_fds_unix_sock(sock, &fd, 1);
 337         if (len < 0) {
 338                 PERROR("lttcomm_send_fds_unix_sock");
 339                 return -1;
 340         }
 341         return 0;
 342 }
 343
 344 static
 345 int do_recv_fd(int sock, int *fd)
 346 {
 347         ssize_t len;
 348
 349         if (*fd < 0) {
 350                 ERR("Invalid file description");
 351                 return 0;
 352         }
 353
 354         len = lttcomm_recv_fds_unix_sock(sock, fd, 1);
 355
 356         if (!len) {
 357                 return -1;
 358         } else if (len < 0) {
 359                 PERROR("lttcomm_recv_fds_unix_sock");
 360                 return -1;
 361         }
 362         return 0;
 363 }
 364
 365 static
 366 int send_fd_to_worker(struct run_as_worker *worker, enum run_as_cmd cmd, int fd)
 367 {
 368         int ret = 0;
 369
 370         switch (cmd) {
 371         case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET:
 372         case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS:
 373                 break;
 374         default:
 375                 return 0;
 376         }
 377
 378         ret = do_send_fd(worker->sockpair[0], fd);
 379         if (ret < 0) {
 380                 PERROR("do_send_fd");
 381                 ret = -1;
 382         }
 383
 384         return ret;
 385 }
 386
 387 static
 388 int send_fd_to_master(struct run_as_worker *worker, enum run_as_cmd cmd, int fd)
 389 {
 390         int ret = 0, ret_close = 0;
 391
 392         switch (cmd) {
 393         case RUN_AS_OPEN:
 394                 break;
 395         default:
 396                 return 0;
 397         }
 398
 399         ret = do_send_fd(worker->sockpair[1], fd);
 400         if (ret < 0) {
 401                 PERROR("do_send_fd error");
 402                 ret = -1;
 403         }
 404
 405         ret_close = close(fd);
 406         if (ret_close < 0) {
 407                 PERROR("close");
 408         }
 409
 410         return ret;
 411 }
 412
 413 static
 414 int recv_fd_from_worker(struct run_as_worker *worker, enum run_as_cmd cmd, int *fd)
 415 {
 416         int ret = 0;
 417
 418         switch (cmd) {
 419         case RUN_AS_OPEN:
 420                 break;
 421         default:
 422                 return 0;
 423         }
 424
 425         ret = do_recv_fd(worker->sockpair[0], fd);
 426         if (ret < 0) {
 427                 PERROR("do_recv_fd error");
 428                 ret = -1;
 429         }
 430
 431         return ret;
 432 }
 433
 434 static
 435 int recv_fd_from_master(struct run_as_worker *worker, enum run_as_cmd cmd, int *fd)
 436 {
 437         int ret = 0;
 438
 439         switch (cmd) {
 440         case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET:
 441         case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS:
 442                 break;
 443         default:
 444                 return 0;
 445         }
 446
 447         ret = do_recv_fd(worker->sockpair[1], fd);
 448         if (ret < 0) {
 449                 PERROR("do_recv_fd error");
 450                 ret = -1;
 451         }
 452
 453         return ret;
 454 }
 455
 456 static
 457 int cleanup_received_fd(enum run_as_cmd cmd, int fd)
 458 {
 459         int ret = 0;
 460
 461         switch (cmd) {
 462         case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET:
 463         case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS:
 464                 break;
 465         default:
 466                 return 0;
 467         }
 468
 469         ret = close(fd);
 470         if (ret < 0) {
 471                 PERROR("close error");
 472                 ret = -1;
 473         }
 474
 475         return ret;
 476 }
 477
 478 /*
 479  * Return < 0 on error, 0 if OK, 1 on hangup.
 480  */
 481 static
 482 int handle_one_cmd(struct run_as_worker *worker)
 483 {
 484         int ret = 0;
 485         struct run_as_data data;
 486         ssize_t readlen, writelen;
 487         struct run_as_ret sendret;
 488         run_as_fct cmd;
 489         uid_t prev_euid;
 490
 491         /*
 492          * Stage 1: Receive run_as_data struct from the master.
 493          * The structure contains the command type and all the parameters needed for
 494          * its execution
 495          */
 496         readlen = lttcomm_recv_unix_sock(worker->sockpair[1], &data,
 497                         sizeof(data));
 498         if (readlen == 0) {
 499                 /* hang up */
 500                 ret = 1;
 501                 goto end;
 502         }
 503         if (readlen < sizeof(data)) {
 504                 PERROR("lttcomm_recv_unix_sock error");
 505                 ret = -1;
 506                 goto end;
 507         }
 508
 509         cmd = run_as_enum_to_fct(data.cmd);
 510         if (!cmd) {
 511                 ret = -1;
 512                 goto end;
 513         }
 514
 515         /*
 516          * Stage 2: Receive file descriptor from master.
 517          * Some commands need a file descriptor as input so if it's needed we
 518          * receive the fd using the Unix socket.
 519          */
 520         ret = recv_fd_from_master(worker, data.cmd, &data.fd);
 521         if (ret < 0) {
 522                 PERROR("recv_fd_from_master error");
 523                 ret = -1;
 524                 goto end;
 525         }
 526
 527         prev_euid = getuid();
 528         if (data.gid != getegid()) {
 529                 ret = setegid(data.gid);
 530                 if (ret < 0) {
 531                         PERROR("setegid");
 532                         goto write_return;
 533                 }
 534         }
 535         if (data.uid != prev_euid) {
 536                 ret = seteuid(data.uid);
 537                 if (ret < 0) {
 538                         PERROR("seteuid");
 539                         goto write_return;
 540                 }
 541         }
 542
 543         /*
 544          * Also set umask to 0 for mkdir executable bit.
 545          */
 546         umask(0);
 547
 548         /*
 549          * Stage 3: Execute the command
 550          */
 551         ret = (*cmd)(&data, &sendret);
 552         if (ret < 0) {
 553                 DBG("Execution of command returned an error");
 554         }
 555
 556 write_return:
 557         ret = cleanup_received_fd(data.cmd, data.fd);
 558         if (ret < 0) {
 559                 ERR("Error cleaning up FD");
 560                 goto end;
 561         }
 562
 563         /*
 564          * Stage 4: Send run_as_ret structure to the master.
 565          * This structure contain the return value of the command and the errno.
 566          */
 567         writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
 568                         sizeof(sendret));
 569         if (writelen < sizeof(sendret)) {
 570                 PERROR("lttcomm_send_unix_sock error");
 571                 ret = -1;
 572                 goto end;
 573         }
 574
 575         /*
 576          * Stage 5: Send file descriptor to the master
 577          * Some commands return a file descriptor so if it's needed we pass it back
 578          * to the master using the Unix socket.
 579          */
 580         ret = send_fd_to_master(worker, data.cmd, sendret.fd);
 581         if (ret < 0) {
 582                 DBG("Sending FD to master returned an error");
 583                 goto end;
 584         }
 585
 586         if (seteuid(prev_euid) < 0) {
 587                 PERROR("seteuid");
 588                 ret = -1;
 589                 goto end;
 590         }
 591         ret = 0;
 592 end:
 593         return ret;
 594 }
 595
 596 static
 597 int run_as_worker(struct run_as_worker *worker)
 598 {
 599         int ret;
 600         ssize_t writelen;
 601         struct run_as_ret sendret;
 602         size_t proc_orig_len;
 603
 604         /*
 605          * Initialize worker. Set a different process cmdline.
 606          */
 607         proc_orig_len = strlen(worker->procname);
 608         memset(worker->procname, 0, proc_orig_len);
 609         strncpy(worker->procname, DEFAULT_RUN_AS_WORKER_NAME, proc_orig_len);
 610
 611         ret = lttng_prctl(PR_SET_NAME,
 612                         (unsigned long) DEFAULT_RUN_AS_WORKER_NAME, 0, 0, 0);
 613         if (ret && ret != -ENOSYS) {
 614                 /* Don't fail as this is not essential. */
 615                 PERROR("prctl PR_SET_NAME");
 616         }
 617
 618         memset(&sendret, 0, sizeof(sendret));
 619
 620         writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
 621                         sizeof(sendret));
 622         if (writelen < sizeof(sendret)) {
 623                 PERROR("lttcomm_send_unix_sock error");
 624                 ret = EXIT_FAILURE;
 625                 goto end;
 626         }
 627
 628         for (;;) {
 629                 ret = handle_one_cmd(worker);
 630                 if (ret < 0) {
 631                         ret = EXIT_FAILURE;
 632                         goto end;
 633                 } else if (ret > 0) {
 634                         break;
 635                 } else {
 636                         continue;       /* Next command. */
 637                 }
 638         }
 639         ret = EXIT_SUCCESS;
 640 end:
 641         return ret;
 642 }
 643
 644 static
 645 int run_as_cmd(struct run_as_worker *worker,
 646                 enum run_as_cmd cmd,
 647                 struct run_as_data *data,
 648                 struct run_as_ret *ret_value,
 649                 uid_t uid, gid_t gid)
 650 {
 651         int ret = 0;
 652         ssize_t readlen, writelen;
 653
 654         /*
 655          * If we are non-root, we can only deal with our own uid.
 656          */
 657         if (geteuid() != 0) {
 658                 if (uid != geteuid()) {
 659                         ret = -1;
 660                         ret_value->_errno = EPERM;
 661                         ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)",
 662                                 (int) uid, (int) geteuid());
 663                         goto end;
 664                 }
 665         }
 666
 667         data->cmd = cmd;
 668         data->uid = uid;
 669         data->gid = gid;
 670
 671         /*
 672          * Stage 1: Send the run_as_data struct to the worker process
 673          */
 674         writelen = lttcomm_send_unix_sock(worker->sockpair[0], data,
 675                         sizeof(*data));
 676         if (writelen < sizeof(*data)) {
 677                 PERROR("Error writing message to run_as");
 678                 ret = -1;
 679                 ret_value->_errno = EIO;
 680                 goto end;
 681         }
 682
 683         /*
 684          * Stage 2: Send file descriptor to the worker process if needed
 685          */
 686         ret = send_fd_to_worker(worker, data->cmd, data->fd);
 687         if (ret) {
 688                 PERROR("do_send_fd error");
 689                 ret = -1;
 690                 ret_value->_errno = EIO;
 691                 goto end;
 692         }
 693
 694         /*
 695          * Stage 3: Wait for the execution of the command
 696          */
 697
 698         /*
 699          * Stage 4: Receive the run_as_ret struct containing the return value and
 700          * errno
 701          */
 702         readlen = lttcomm_recv_unix_sock(worker->sockpair[0], ret_value,
 703                         sizeof(*ret_value));
 704         if (!readlen) {
 705                 ERR("Run-as worker has hung-up during run_as_cmd");
 706                 ret = -1;
 707                 ret_value->_errno = EIO;
 708                 goto end;
 709         } else if (readlen < sizeof(*ret_value)) {
 710                 PERROR("Error reading response from run_as");
 711                 ret = -1;
 712                 ret_value->_errno = errno;
 713         }
 714
 715         /*
 716          * Stage 5: Receive file descriptor if needed
 717          */
 718         ret = recv_fd_from_worker(worker, data->cmd, &ret_value->fd);
 719         if (ret < 0) {
 720                 ERR("Error receiving fd");
 721                 ret = -1;
 722                 ret_value->_errno = EIO;
 723         }
 724
 725 end:
 726         return ret;
 727 }
 728
 729 /*
 730  * This is for debugging ONLY and should not be considered secure.
 731  */
 732 static
 733 int run_as_noworker(enum run_as_cmd cmd,
 734                 struct run_as_data *data, struct run_as_ret *ret_value,
 735                 uid_t uid, gid_t gid)
 736 {
 737         int ret, saved_errno;
 738         mode_t old_mask;
 739         run_as_fct fct;
 740
 741         fct = run_as_enum_to_fct(cmd);
 742         if (!fct) {
 743                 errno = -ENOSYS;
 744                 ret = -1;
 745                 goto end;
 746         }
 747         old_mask = umask(0);
 748         ret = fct(data, ret_value);
 749         saved_errno = ret_value->_errno;
 750         umask(old_mask);
 751         errno = saved_errno;
 752 end:
 753         return ret;
 754 }
 755
 756 static
 757 int run_as_restart_worker(struct run_as_worker *worker)
 758 {
 759         int ret = 0;
 760         char *procname = NULL;
 761
 762         procname = worker->procname;
 763
 764         /* Close socket to run_as worker process and clean up the zombie process */
 765         run_as_destroy_worker();
 766
 767         /* Create a new run_as worker process*/
 768         ret = run_as_create_worker(procname);
 769         if (ret < 0 ) {
 770                 ERR("Restarting the worker process failed");
 771                 ret = -1;
 772                 goto err;
 773         }
 774 err:
 775         return ret;
 776 }
 777
 778 static
 779 int run_as(enum run_as_cmd cmd, struct run_as_data *data,
 780                    struct run_as_ret *ret_value, uid_t uid, gid_t gid)
 781 {
 782         int ret, saved_errno;
 783
 784         if (use_clone()) {
 785                 DBG("Using run_as worker");
 786                 pthread_mutex_lock(&worker_lock);
 787                 assert(global_worker);
 788
 789                 ret = run_as_cmd(global_worker, cmd, data, ret_value, uid, gid);
 790                 saved_errno = ret_value->_errno;
 791
 792                 pthread_mutex_unlock(&worker_lock);
 793                 /*
 794                  * If the worker thread crashed the errno is set to EIO. we log
 795                  * the error and  start a new worker process.
 796                  */
 797                 if (ret == -1 && saved_errno == EIO) {
 798                         DBG("Socket closed unexpectedly... "
 799                                         "Restarting the worker process");
 800                         ret = run_as_restart_worker(global_worker);
 801
 802                         if (ret == -1) {
 803                                 ERR("Failed to restart worker process.");
 804                                 goto err;
 805                         }
 806                 }
 807         } else {
 808                 DBG("Using run_as without worker");
 809                 ret = run_as_noworker(cmd, data, ret_value, uid, gid);
 810         }
 811 err:
 812         return ret;
 813 }
 814
 815 LTTNG_HIDDEN
 816 int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid)
 817 {
 818         struct run_as_data data;
 819         struct run_as_ret ret;
 820
 821         memset(&data, 0, sizeof(data));
 822         memset(&ret, 0, sizeof(ret));
 823         DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d",
 824                         path, (int) mode, (int) uid, (int) gid);
 825         strncpy(data.u.mkdir.path, path, PATH_MAX - 1);
 826         data.u.mkdir.path[PATH_MAX - 1] = '\0';
 827         data.u.mkdir.mode = mode;
 828
 829         run_as(RUN_AS_MKDIR_RECURSIVE, &data, &ret, uid, gid);
 830         errno = ret._errno;
 831         return ret.u.mkdir.ret;
 832 }
 833
 834 LTTNG_HIDDEN
 835 int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid)
 836 {
 837         struct run_as_data data;
 838         struct run_as_ret ret;
 839
 840         memset(&data, 0, sizeof(data));
 841         memset(&ret, 0, sizeof(ret));
 842
 843         DBG3("mkdir() %s with mode %d for uid %d and gid %d",
 844                         path, (int) mode, (int) uid, (int) gid);
 845         strncpy(data.u.mkdir.path, path, PATH_MAX - 1);
 846         data.u.mkdir.path[PATH_MAX - 1] = '\0';
 847         data.u.mkdir.mode = mode;
 848         run_as(RUN_AS_MKDIR, &data, &ret, uid, gid);
 849         errno = ret._errno;
 850         return ret.u.mkdir.ret;
 851 }
 852
 853 LTTNG_HIDDEN
 854 int run_as_open(const char *path, int flags, mode_t mode, uid_t uid, gid_t gid)
 855 {
 856         struct run_as_data data;
 857         struct run_as_ret ret;
 858
 859         memset(&data, 0, sizeof(data));
 860         memset(&ret, 0, sizeof(ret));
 861
 862         DBG3("open() %s with flags %X mode %d for uid %d and gid %d",
 863                         path, flags, (int) mode, (int) uid, (int) gid);
 864         strncpy(data.u.open.path, path, PATH_MAX - 1);
 865         data.u.open.path[PATH_MAX - 1] = '\0';
 866         data.u.open.flags = flags;
 867         data.u.open.mode = mode;
 868         run_as(RUN_AS_OPEN, &data, &ret, uid, gid);
 869         errno = ret._errno;
 870         ret.u.open.ret = ret.fd;
 871         return ret.u.open.ret;
 872 }
 873
 874 LTTNG_HIDDEN
 875 int run_as_unlink(const char *path, uid_t uid, gid_t gid)
 876 {
 877         struct run_as_data data;
 878         struct run_as_ret ret;
 879
 880         memset(&data, 0, sizeof(data));
 881         memset(&ret, 0, sizeof(ret));
 882
 883         DBG3("unlink() %s with for uid %d and gid %d",
 884                         path, (int) uid, (int) gid);
 885         strncpy(data.u.unlink.path, path, PATH_MAX - 1);
 886         data.u.unlink.path[PATH_MAX - 1] = '\0';
 887         run_as(RUN_AS_UNLINK, &data, &ret, uid, gid);
 888         errno = ret._errno;
 889         return ret.u.unlink.ret;
 890 }
 891
 892 LTTNG_HIDDEN
 893 int run_as_rmdir_recursive(const char *path, uid_t uid, gid_t gid)
 894 {
 895         struct run_as_data data;
 896         struct run_as_ret ret;
 897
 898         memset(&data, 0, sizeof(data));
 899         memset(&ret, 0, sizeof(ret));
 900
 901         DBG3("rmdir_recursive() %s with for uid %d and gid %d",
 902                         path, (int) uid, (int) gid);
 903         strncpy(data.u.rmdir_recursive.path, path, PATH_MAX - 1);
 904         data.u.rmdir_recursive.path[PATH_MAX - 1] = '\0';
 905         run_as(RUN_AS_RMDIR_RECURSIVE, &data, &ret, uid, gid);
 906         errno = ret._errno;
 907         return ret.u.rmdir_recursive.ret;
 908 }
 909
 910 LTTNG_HIDDEN
 911 int run_as_extract_elf_symbol_offset(int fd, const char* function,
 912                 uid_t uid, gid_t gid, uint64_t *offset)
 913 {
 914         struct run_as_data data;
 915         struct run_as_ret ret;
 916
 917         DBG3("extract_elf_symbol_offset() on fd=%d and function=%s "
 918                 "with for uid %d and gid %d", fd, function, (int) uid, (int) gid);
 919
 920         data.fd = fd;
 921
 922         strncpy(data.u.extract_elf_symbol_offset.function, function, LTTNG_SYMBOL_NAME_LEN - 1);
 923
 924         data.u.extract_elf_symbol_offset.function[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 925
 926         run_as(RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET, &data, &ret, uid, gid);
 927
 928         errno = ret._errno;
 929
 930         if (ret._error) {
 931                 return -1;
 932         }
 933
 934         *offset = ret.u.extract_elf_symbol_offset.offset;
 935         return 0;
 936 }
 937
 938 LTTNG_HIDDEN
 939 int run_as_extract_sdt_probe_offsets(int fd, const char* provider_name,
 940                 const char* probe_name, uid_t uid, gid_t gid,
 941                 uint64_t **offsets, uint32_t *num_offset)
 942 {
 943         struct run_as_data data;
 944         struct run_as_ret ret;
 945
 946         DBG3("extract_sdt_probe_offsets() on fd=%d, probe_name=%s and "
 947                 "provider_name=%s with for uid %d and gid %d", fd, probe_name,
 948                 provider_name, (int) uid, (int) gid);
 949
 950         data.fd = fd;
 951
 952         strncpy(data.u.extract_sdt_probe_offsets.probe_name, probe_name, LTTNG_SYMBOL_NAME_LEN - 1);
 953         strncpy(data.u.extract_sdt_probe_offsets.provider_name, provider_name, LTTNG_SYMBOL_NAME_LEN - 1);
 954
 955         data.u.extract_sdt_probe_offsets.probe_name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 956         data.u.extract_sdt_probe_offsets.provider_name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 957
 958         run_as(RUN_AS_EXTRACT_SDT_PROBE_OFFSETS, &data, &ret, uid, gid);
 959
 960         errno = ret._errno;
 961
 962         if (ret._error) {
 963                 return -1;
 964         }
 965
 966         *num_offset = ret.u.extract_sdt_probe_offsets.num_offset;
 967
 968         *offsets = zmalloc(*num_offset * sizeof(uint64_t));
 969         if (!*offsets) {
 970                 return -ENOMEM;
 971         }
 972
 973         memcpy(*offsets, ret.u.extract_sdt_probe_offsets.offsets, *num_offset * sizeof(uint64_t));
 974         return 0;
 975 }
 976
 977 static
 978 int reset_sighandler(void)
 979 {
 980         int sig;
 981
 982         DBG("Resetting run_as worker signal handlers to default");
 983         for (sig = 1; sig <= 31; sig++) {
 984                 (void) signal(sig, SIG_DFL);
 985         }
 986         return 0;
 987 }
 988
 989 static
 990 void worker_sighandler(int sig)
 991 {
 992         const char *signame;
 993
 994         /*
 995          * The worker will inherit its parent's signals since they are part of
 996          * the same process group. However, in the case of SIGINT and SIGTERM,
 997          * we want to give the worker a chance to teardown gracefully when its
 998          * parent closes the command socket.
 999          */
1000         switch (sig) {
1001         case SIGINT:
1002                 signame = "SIGINT";
1003                 break;
1004         case SIGTERM:
1005                 signame = "SIGTERM";
1006                 break;
1007         default:
1008                 signame = NULL;
1009         }
1010
1011         if (signame) {
1012                 DBG("run_as worker received signal %s", signame);
1013         } else {
1014                 DBG("run_as_worker received signal %d", sig);
1015         }
1016 }
1017
1018 static
1019 int set_worker_sighandlers(void)
1020 {
1021         int ret = 0;
1022         sigset_t sigset;
1023         struct sigaction sa;
1024
1025         if ((ret = sigemptyset(&sigset)) < 0) {
1026                 PERROR("sigemptyset");
1027                 goto end;
1028         }
1029
1030         sa.sa_handler = worker_sighandler;
1031         sa.sa_mask = sigset;
1032         sa.sa_flags = 0;
1033         if ((ret = sigaction(SIGINT, &sa, NULL)) < 0) {
1034                 PERROR("sigaction SIGINT");
1035                 goto end;
1036         }
1037
1038         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
1039                 PERROR("sigaction SIGTERM");
1040                 goto end;
1041         }
1042
1043         DBG("run_as signal handler set for SIGTERM and SIGINT");
1044 end:
1045         return ret;
1046 }
1047
1048 LTTNG_HIDDEN
1049 int run_as_create_worker(char *procname)
1050 {
1051         pid_t pid;
1052         int i, ret = 0;
1053         ssize_t readlen;
1054         struct run_as_ret recvret;
1055         struct run_as_worker *worker;
1056
1057         pthread_mutex_lock(&worker_lock);
1058         assert(!global_worker);
1059         if (!use_clone()) {
1060                 /*
1061                  * Don't initialize a worker, all run_as tasks will be performed
1062                  * in the current process.
1063                  */
1064                 ret = 0;
1065                 goto end;
1066         }
1067         worker = zmalloc(sizeof(*worker));
1068         if (!worker) {
1069                 ret = -ENOMEM;
1070                 goto end;
1071         }
1072         worker->procname = procname;
1073         /* Create unix socket. */
1074         if (lttcomm_create_anon_unix_socketpair(worker->sockpair) < 0) {
1075                 ret = -1;
1076                 goto error_sock;
1077         }
1078
1079         /* Fork worker. */
1080         pid = fork();
1081         if (pid < 0) {
1082                 PERROR("fork");
1083                 ret = -1;
1084                 goto error_fork;
1085         } else if (pid == 0) {
1086                 /* Child */
1087
1088                 reset_sighandler();
1089
1090                 set_worker_sighandlers();
1091
1092                 /* The child has no use for this lock. */
1093                 pthread_mutex_unlock(&worker_lock);
1094                 /* Just close, no shutdown. */
1095                 if (close(worker->sockpair[0])) {
1096                         PERROR("close");
1097                         exit(EXIT_FAILURE);
1098                 }
1099
1100                 /*
1101                  * Close all FDs aside from STDIN, STDOUT, STDERR and sockpair[1]
1102                  * Sockpair[1] is used as a control channel with the master
1103                  */
1104                 for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) {
1105                         if (i != worker->sockpair[1]) {
1106                                 (void) close(i);
1107                         }
1108                 }
1109
1110                 worker->sockpair[0] = -1;
1111                 ret = run_as_worker(worker);
1112                 if (lttcomm_close_unix_sock(worker->sockpair[1])) {
1113                         PERROR("close");
1114                         ret = -1;
1115                 }
1116                 worker->sockpair[1] = -1;
1117                 LOG(ret ? PRINT_ERR : PRINT_DBG, "run_as worker exiting (ret = %d)", ret);
1118                 exit(ret ? EXIT_FAILURE : EXIT_SUCCESS);
1119         } else {
1120                 /* Parent */
1121
1122                 /* Just close, no shutdown. */
1123                 if (close(worker->sockpair[1])) {
1124                         PERROR("close");
1125                         ret = -1;
1126                         goto error_fork;
1127                 }
1128                 worker->sockpair[1] = -1;
1129                 worker->pid = pid;
1130                 /* Wait for worker to become ready. */
1131                 readlen = lttcomm_recv_unix_sock(worker->sockpair[0],
1132                                 &recvret, sizeof(recvret));
1133                 if (readlen < sizeof(recvret)) {
1134                         ERR("readlen: %zd", readlen);
1135                         PERROR("Error reading response from run_as at creation");
1136                         ret = -1;
1137                         goto error_fork;
1138                 }
1139                 global_worker = worker;
1140         }
1141 end:
1142         pthread_mutex_unlock(&worker_lock);
1143         return ret;
1144
1145         /* Error handling. */
1146 error_fork:
1147         for (i = 0; i < 2; i++) {
1148                 if (worker->sockpair[i] < 0) {
1149                         continue;
1150                 }
1151                 if (lttcomm_close_unix_sock(worker->sockpair[i])) {
1152                         PERROR("close");
1153                 }
1154                 worker->sockpair[i] = -1;
1155         }
1156 error_sock:
1157         free(worker);
1158         pthread_mutex_unlock(&worker_lock);
1159         return ret;
1160 }
1161
1162 LTTNG_HIDDEN
1163 void run_as_destroy_worker(void)
1164 {
1165         struct run_as_worker *worker = global_worker;
1166
1167         DBG("Destroying run_as worker");
1168         pthread_mutex_lock(&worker_lock);
1169         if (!worker) {
1170                 goto end;
1171         }
1172         /* Close unix socket */
1173         DBG("Closing run_as worker socket");
1174         if (lttcomm_close_unix_sock(worker->sockpair[0])) {
1175                 PERROR("close");
1176         }
1177         worker->sockpair[0] = -1;
1178         /* Wait for worker. */
1179         for (;;) {
1180                 int status;
1181                 pid_t wait_ret;
1182
1183                 wait_ret = waitpid(worker->pid, &status, 0);
1184                 if (wait_ret < 0) {
1185                         if (errno == EINTR) {
1186                                 continue;
1187                         }
1188                         PERROR("waitpid");
1189                         break;
1190                 }
1191
1192                 if (WIFEXITED(status)) {
1193                         LOG(WEXITSTATUS(status) == 0 ? PRINT_DBG : PRINT_ERR,
1194                                         DEFAULT_RUN_AS_WORKER_NAME " terminated with status code %d",
1195                                         WEXITSTATUS(status));
1196                         break;
1197                 } else if (WIFSIGNALED(status)) {
1198                         ERR(DEFAULT_RUN_AS_WORKER_NAME " was killed by signal %d",
1199                                         WTERMSIG(status));
1200                         break;
1201                 }
1202         }
1203         free(worker);
1204         global_worker = NULL;
1205 end:
1206         pthread_mutex_unlock(&worker_lock);
1207 }