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                         sendret._error = true;
 532                         sendret._errno = errno;
 533                         PERROR("setegid");
 534                         goto write_return;
 535                 }
 536         }
 537         if (data.uid != prev_euid) {
 538                 ret = seteuid(data.uid);
 539                 if (ret < 0) {
 540                         sendret._error = true;
 541                         sendret._errno = errno;
 542                         PERROR("seteuid");
 543                         goto write_return;
 544                 }
 545         }
 546
 547         /*
 548          * Also set umask to 0 for mkdir executable bit.
 549          */
 550         umask(0);
 551
 552         /*
 553          * Stage 3: Execute the command
 554          */
 555         ret = (*cmd)(&data, &sendret);
 556         if (ret < 0) {
 557                 DBG("Execution of command returned an error");
 558         }
 559
 560 write_return:
 561         ret = cleanup_received_fd(data.cmd, data.fd);
 562         if (ret < 0) {
 563                 ERR("Error cleaning up FD");
 564                 goto end;
 565         }
 566
 567         /*
 568          * Stage 4: Send run_as_ret structure to the master.
 569          * This structure contain the return value of the command and the errno.
 570          */
 571         writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
 572                         sizeof(sendret));
 573         if (writelen < sizeof(sendret)) {
 574                 PERROR("lttcomm_send_unix_sock error");
 575                 ret = -1;
 576                 goto end;
 577         }
 578
 579         /*
 580          * Stage 5: Send file descriptor to the master
 581          * Some commands return a file descriptor so if it's needed we pass it back
 582          * to the master using the Unix socket.
 583          */
 584         ret = send_fd_to_master(worker, data.cmd, sendret.fd);
 585         if (ret < 0) {
 586                 DBG("Sending FD to master returned an error");
 587                 goto end;
 588         }
 589
 590         if (seteuid(prev_euid) < 0) {
 591                 PERROR("seteuid");
 592                 ret = -1;
 593                 goto end;
 594         }
 595         ret = 0;
 596 end:
 597         return ret;
 598 }
 599
 600 static
 601 int run_as_worker(struct run_as_worker *worker)
 602 {
 603         int ret;
 604         ssize_t writelen;
 605         struct run_as_ret sendret;
 606         size_t proc_orig_len;
 607
 608         /*
 609          * Initialize worker. Set a different process cmdline.
 610          */
 611         proc_orig_len = strlen(worker->procname);
 612         memset(worker->procname, 0, proc_orig_len);
 613         strncpy(worker->procname, DEFAULT_RUN_AS_WORKER_NAME, proc_orig_len);
 614
 615         ret = lttng_prctl(PR_SET_NAME,
 616                         (unsigned long) DEFAULT_RUN_AS_WORKER_NAME, 0, 0, 0);
 617         if (ret && ret != -ENOSYS) {
 618                 /* Don't fail as this is not essential. */
 619                 PERROR("prctl PR_SET_NAME");
 620         }
 621
 622         memset(&sendret, 0, sizeof(sendret));
 623
 624         writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
 625                         sizeof(sendret));
 626         if (writelen < sizeof(sendret)) {
 627                 PERROR("lttcomm_send_unix_sock error");
 628                 ret = EXIT_FAILURE;
 629                 goto end;
 630         }
 631
 632         for (;;) {
 633                 ret = handle_one_cmd(worker);
 634                 if (ret < 0) {
 635                         ret = EXIT_FAILURE;
 636                         goto end;
 637                 } else if (ret > 0) {
 638                         break;
 639                 } else {
 640                         continue;       /* Next command. */
 641                 }
 642         }
 643         ret = EXIT_SUCCESS;
 644 end:
 645         return ret;
 646 }
 647
 648 static
 649 int run_as_cmd(struct run_as_worker *worker,
 650                 enum run_as_cmd cmd,
 651                 struct run_as_data *data,
 652                 struct run_as_ret *ret_value,
 653                 uid_t uid, gid_t gid)
 654 {
 655         int ret = 0;
 656         ssize_t readlen, writelen;
 657
 658         /*
 659          * If we are non-root, we can only deal with our own uid.
 660          */
 661         if (geteuid() != 0) {
 662                 if (uid != geteuid()) {
 663                         ret = -1;
 664                         ret_value->_errno = EPERM;
 665                         ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)",
 666                                 (int) uid, (int) geteuid());
 667                         goto end;
 668                 }
 669         }
 670
 671         data->cmd = cmd;
 672         data->uid = uid;
 673         data->gid = gid;
 674
 675         /*
 676          * Stage 1: Send the run_as_data struct to the worker process
 677          */
 678         writelen = lttcomm_send_unix_sock(worker->sockpair[0], data,
 679                         sizeof(*data));
 680         if (writelen < sizeof(*data)) {
 681                 PERROR("Error writing message to run_as");
 682                 ret = -1;
 683                 ret_value->_errno = EIO;
 684                 goto end;
 685         }
 686
 687         /*
 688          * Stage 2: Send file descriptor to the worker process if needed
 689          */
 690         ret = send_fd_to_worker(worker, data->cmd, data->fd);
 691         if (ret) {
 692                 PERROR("do_send_fd error");
 693                 ret = -1;
 694                 ret_value->_errno = EIO;
 695                 goto end;
 696         }
 697
 698         /*
 699          * Stage 3: Wait for the execution of the command
 700          */
 701
 702         /*
 703          * Stage 4: Receive the run_as_ret struct containing the return value and
 704          * errno
 705          */
 706         readlen = lttcomm_recv_unix_sock(worker->sockpair[0], ret_value,
 707                         sizeof(*ret_value));
 708         if (!readlen) {
 709                 ERR("Run-as worker has hung-up during run_as_cmd");
 710                 ret = -1;
 711                 ret_value->_errno = EIO;
 712                 goto end;
 713         } else if (readlen < sizeof(*ret_value)) {
 714                 PERROR("Error reading response from run_as");
 715                 ret = -1;
 716                 ret_value->_errno = errno;
 717                 goto end;
 718         }
 719
 720         /*
 721          * Stage 5: Receive file descriptor if needed
 722          */
 723         ret = recv_fd_from_worker(worker, data->cmd, &ret_value->fd);
 724         if (ret < 0) {
 725                 ERR("Error receiving fd");
 726                 ret = -1;
 727                 ret_value->_errno = EIO;
 728         }
 729
 730 end:
 731         return ret;
 732 }
 733
 734 /*
 735  * This is for debugging ONLY and should not be considered secure.
 736  */
 737 static
 738 int run_as_noworker(enum run_as_cmd cmd,
 739                 struct run_as_data *data, struct run_as_ret *ret_value,
 740                 uid_t uid, gid_t gid)
 741 {
 742         int ret, saved_errno;
 743         mode_t old_mask;
 744         run_as_fct fct;
 745
 746         fct = run_as_enum_to_fct(cmd);
 747         if (!fct) {
 748                 errno = -ENOSYS;
 749                 ret = -1;
 750                 goto end;
 751         }
 752         old_mask = umask(0);
 753         ret = fct(data, ret_value);
 754         saved_errno = ret_value->_errno;
 755         umask(old_mask);
 756         errno = saved_errno;
 757 end:
 758         return ret;
 759 }
 760
 761 static
 762 int run_as_restart_worker(struct run_as_worker *worker)
 763 {
 764         int ret = 0;
 765         char *procname = NULL;
 766
 767         procname = worker->procname;
 768
 769         /* Close socket to run_as worker process and clean up the zombie process */
 770         run_as_destroy_worker();
 771
 772         /* Create a new run_as worker process*/
 773         ret = run_as_create_worker(procname);
 774         if (ret < 0 ) {
 775                 ERR("Restarting the worker process failed");
 776                 ret = -1;
 777                 goto err;
 778         }
 779 err:
 780         return ret;
 781 }
 782
 783 static
 784 int run_as(enum run_as_cmd cmd, struct run_as_data *data,
 785                    struct run_as_ret *ret_value, uid_t uid, gid_t gid)
 786 {
 787         int ret, saved_errno;
 788
 789         if (use_clone()) {
 790                 DBG("Using run_as worker");
 791                 pthread_mutex_lock(&worker_lock);
 792                 assert(global_worker);
 793
 794                 ret = run_as_cmd(global_worker, cmd, data, ret_value, uid, gid);
 795                 saved_errno = ret_value->_errno;
 796
 797                 pthread_mutex_unlock(&worker_lock);
 798                 /*
 799                  * If the worker thread crashed the errno is set to EIO. we log
 800                  * the error and  start a new worker process.
 801                  */
 802                 if (ret == -1 && saved_errno == EIO) {
 803                         DBG("Socket closed unexpectedly... "
 804                                         "Restarting the worker process");
 805                         ret = run_as_restart_worker(global_worker);
 806
 807                         if (ret == -1) {
 808                                 ERR("Failed to restart worker process.");
 809                                 goto err;
 810                         }
 811                 }
 812         } else {
 813                 DBG("Using run_as without worker");
 814                 ret = run_as_noworker(cmd, data, ret_value, uid, gid);
 815         }
 816 err:
 817         return ret;
 818 }
 819
 820 LTTNG_HIDDEN
 821 int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid)
 822 {
 823         struct run_as_data data;
 824         struct run_as_ret ret;
 825
 826         memset(&data, 0, sizeof(data));
 827         memset(&ret, 0, sizeof(ret));
 828         DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d",
 829                         path, (int) mode, (int) uid, (int) gid);
 830         strncpy(data.u.mkdir.path, path, PATH_MAX - 1);
 831         data.u.mkdir.path[PATH_MAX - 1] = '\0';
 832         data.u.mkdir.mode = mode;
 833
 834         run_as(RUN_AS_MKDIR_RECURSIVE, &data, &ret, uid, gid);
 835         errno = ret._errno;
 836         return ret.u.mkdir.ret;
 837 }
 838
 839 LTTNG_HIDDEN
 840 int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid)
 841 {
 842         struct run_as_data data;
 843         struct run_as_ret ret;
 844
 845         memset(&data, 0, sizeof(data));
 846         memset(&ret, 0, sizeof(ret));
 847
 848         DBG3("mkdir() %s with mode %d for uid %d and gid %d",
 849                         path, (int) mode, (int) uid, (int) gid);
 850         strncpy(data.u.mkdir.path, path, PATH_MAX - 1);
 851         data.u.mkdir.path[PATH_MAX - 1] = '\0';
 852         data.u.mkdir.mode = mode;
 853         run_as(RUN_AS_MKDIR, &data, &ret, uid, gid);
 854         errno = ret._errno;
 855         return ret.u.mkdir.ret;
 856 }
 857
 858 LTTNG_HIDDEN
 859 int run_as_open(const char *path, int flags, mode_t mode, uid_t uid, gid_t gid)
 860 {
 861         struct run_as_data data;
 862         struct run_as_ret ret;
 863
 864         memset(&data, 0, sizeof(data));
 865         memset(&ret, 0, sizeof(ret));
 866
 867         DBG3("open() %s with flags %X mode %d for uid %d and gid %d",
 868                         path, flags, (int) mode, (int) uid, (int) gid);
 869         strncpy(data.u.open.path, path, PATH_MAX - 1);
 870         data.u.open.path[PATH_MAX - 1] = '\0';
 871         data.u.open.flags = flags;
 872         data.u.open.mode = mode;
 873         run_as(RUN_AS_OPEN, &data, &ret, uid, gid);
 874         errno = ret._errno;
 875         ret.u.open.ret = ret.fd;
 876         return ret.u.open.ret;
 877 }
 878
 879 LTTNG_HIDDEN
 880 int run_as_unlink(const char *path, uid_t uid, gid_t gid)
 881 {
 882         struct run_as_data data;
 883         struct run_as_ret ret;
 884
 885         memset(&data, 0, sizeof(data));
 886         memset(&ret, 0, sizeof(ret));
 887
 888         DBG3("unlink() %s with for uid %d and gid %d",
 889                         path, (int) uid, (int) gid);
 890         strncpy(data.u.unlink.path, path, PATH_MAX - 1);
 891         data.u.unlink.path[PATH_MAX - 1] = '\0';
 892         run_as(RUN_AS_UNLINK, &data, &ret, uid, gid);
 893         errno = ret._errno;
 894         return ret.u.unlink.ret;
 895 }
 896
 897 LTTNG_HIDDEN
 898 int run_as_rmdir_recursive(const char *path, uid_t uid, gid_t gid)
 899 {
 900         struct run_as_data data;
 901         struct run_as_ret ret;
 902
 903         memset(&data, 0, sizeof(data));
 904         memset(&ret, 0, sizeof(ret));
 905
 906         DBG3("rmdir_recursive() %s with for uid %d and gid %d",
 907                         path, (int) uid, (int) gid);
 908         strncpy(data.u.rmdir_recursive.path, path, PATH_MAX - 1);
 909         data.u.rmdir_recursive.path[PATH_MAX - 1] = '\0';
 910         run_as(RUN_AS_RMDIR_RECURSIVE, &data, &ret, uid, gid);
 911         errno = ret._errno;
 912         return ret.u.rmdir_recursive.ret;
 913 }
 914
 915 LTTNG_HIDDEN
 916 int run_as_extract_elf_symbol_offset(int fd, const char* function,
 917                 uid_t uid, gid_t gid, uint64_t *offset)
 918 {
 919         struct run_as_data data;
 920         struct run_as_ret ret;
 921
 922         DBG3("extract_elf_symbol_offset() on fd=%d and function=%s "
 923                 "with for uid %d and gid %d", fd, function, (int) uid, (int) gid);
 924
 925         data.fd = fd;
 926
 927         strncpy(data.u.extract_elf_symbol_offset.function, function, LTTNG_SYMBOL_NAME_LEN - 1);
 928
 929         data.u.extract_elf_symbol_offset.function[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 930
 931         run_as(RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET, &data, &ret, uid, gid);
 932
 933         errno = ret._errno;
 934
 935         if (ret._error) {
 936                 return -1;
 937         }
 938
 939         *offset = ret.u.extract_elf_symbol_offset.offset;
 940         return 0;
 941 }
 942
 943 LTTNG_HIDDEN
 944 int run_as_extract_sdt_probe_offsets(int fd, const char* provider_name,
 945                 const char* probe_name, uid_t uid, gid_t gid,
 946                 uint64_t **offsets, uint32_t *num_offset)
 947 {
 948         struct run_as_data data;
 949         struct run_as_ret ret;
 950
 951         DBG3("extract_sdt_probe_offsets() on fd=%d, probe_name=%s and "
 952                 "provider_name=%s with for uid %d and gid %d", fd, probe_name,
 953                 provider_name, (int) uid, (int) gid);
 954
 955         data.fd = fd;
 956
 957         strncpy(data.u.extract_sdt_probe_offsets.probe_name, probe_name, LTTNG_SYMBOL_NAME_LEN - 1);
 958         strncpy(data.u.extract_sdt_probe_offsets.provider_name, provider_name, LTTNG_SYMBOL_NAME_LEN - 1);
 959
 960         data.u.extract_sdt_probe_offsets.probe_name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 961         data.u.extract_sdt_probe_offsets.provider_name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 962
 963         run_as(RUN_AS_EXTRACT_SDT_PROBE_OFFSETS, &data, &ret, uid, gid);
 964
 965         errno = ret._errno;
 966
 967         if (ret._error) {
 968                 return -1;
 969         }
 970
 971         *num_offset = ret.u.extract_sdt_probe_offsets.num_offset;
 972
 973         *offsets = zmalloc(*num_offset * sizeof(uint64_t));
 974         if (!*offsets) {
 975                 return -ENOMEM;
 976         }
 977
 978         memcpy(*offsets, ret.u.extract_sdt_probe_offsets.offsets, *num_offset * sizeof(uint64_t));
 979         return 0;
 980 }
 981
 982 static
 983 int reset_sighandler(void)
 984 {
 985         int sig;
 986
 987         DBG("Resetting run_as worker signal handlers to default");
 988         for (sig = 1; sig <= 31; sig++) {
 989                 (void) signal(sig, SIG_DFL);
 990         }
 991         return 0;
 992 }
 993
 994 static
 995 void worker_sighandler(int sig)
 996 {
 997         const char *signame;
 998
 999         /*
1000          * The worker will inherit its parent's signals since they are part of
1001          * the same process group. However, in the case of SIGINT and SIGTERM,
1002          * we want to give the worker a chance to teardown gracefully when its
1003          * parent closes the command socket.
1004          */
1005         switch (sig) {
1006         case SIGINT:
1007                 signame = "SIGINT";
1008                 break;
1009         case SIGTERM:
1010                 signame = "SIGTERM";
1011                 break;
1012         default:
1013                 signame = NULL;
1014         }
1015
1016         if (signame) {
1017                 DBG("run_as worker received signal %s", signame);
1018         } else {
1019                 DBG("run_as_worker received signal %d", sig);
1020         }
1021 }
1022
1023 static
1024 int set_worker_sighandlers(void)
1025 {
1026         int ret = 0;
1027         sigset_t sigset;
1028         struct sigaction sa;
1029
1030         if ((ret = sigemptyset(&sigset)) < 0) {
1031                 PERROR("sigemptyset");
1032                 goto end;
1033         }
1034
1035         sa.sa_handler = worker_sighandler;
1036         sa.sa_mask = sigset;
1037         sa.sa_flags = 0;
1038         if ((ret = sigaction(SIGINT, &sa, NULL)) < 0) {
1039                 PERROR("sigaction SIGINT");
1040                 goto end;
1041         }
1042
1043         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
1044                 PERROR("sigaction SIGTERM");
1045                 goto end;
1046         }
1047
1048         DBG("run_as signal handler set for SIGTERM and SIGINT");
1049 end:
1050         return ret;
1051 }
1052
1053 LTTNG_HIDDEN
1054 int run_as_create_worker(char *procname)
1055 {
1056         pid_t pid;
1057         int i, ret = 0;
1058         ssize_t readlen;
1059         struct run_as_ret recvret;
1060         struct run_as_worker *worker;
1061
1062         pthread_mutex_lock(&worker_lock);
1063         assert(!global_worker);
1064         if (!use_clone()) {
1065                 /*
1066                  * Don't initialize a worker, all run_as tasks will be performed
1067                  * in the current process.
1068                  */
1069                 ret = 0;
1070                 goto end;
1071         }
1072         worker = zmalloc(sizeof(*worker));
1073         if (!worker) {
1074                 ret = -ENOMEM;
1075                 goto end;
1076         }
1077         worker->procname = procname;
1078         /* Create unix socket. */
1079         if (lttcomm_create_anon_unix_socketpair(worker->sockpair) < 0) {
1080                 ret = -1;
1081                 goto error_sock;
1082         }
1083
1084         /* Fork worker. */
1085         pid = fork();
1086         if (pid < 0) {
1087                 PERROR("fork");
1088                 ret = -1;
1089                 goto error_fork;
1090         } else if (pid == 0) {
1091                 /* Child */
1092
1093                 reset_sighandler();
1094
1095                 set_worker_sighandlers();
1096
1097                 /* The child has no use for this lock. */
1098                 pthread_mutex_unlock(&worker_lock);
1099                 /* Just close, no shutdown. */
1100                 if (close(worker->sockpair[0])) {
1101                         PERROR("close");
1102                         exit(EXIT_FAILURE);
1103                 }
1104
1105                 /*
1106                  * Close all FDs aside from STDIN, STDOUT, STDERR and sockpair[1]
1107                  * Sockpair[1] is used as a control channel with the master
1108                  */
1109                 for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) {
1110                         if (i != worker->sockpair[1]) {
1111                                 (void) close(i);
1112                         }
1113                 }
1114
1115                 worker->sockpair[0] = -1;
1116                 ret = run_as_worker(worker);
1117                 if (lttcomm_close_unix_sock(worker->sockpair[1])) {
1118                         PERROR("close");
1119                         ret = -1;
1120                 }
1121                 worker->sockpair[1] = -1;
1122                 LOG(ret ? PRINT_ERR : PRINT_DBG, "run_as worker exiting (ret = %d)", ret);
1123                 exit(ret ? EXIT_FAILURE : EXIT_SUCCESS);
1124         } else {
1125                 /* Parent */
1126
1127                 /* Just close, no shutdown. */
1128                 if (close(worker->sockpair[1])) {
1129                         PERROR("close");
1130                         ret = -1;
1131                         goto error_fork;
1132                 }
1133                 worker->sockpair[1] = -1;
1134                 worker->pid = pid;
1135                 /* Wait for worker to become ready. */
1136                 readlen = lttcomm_recv_unix_sock(worker->sockpair[0],
1137                                 &recvret, sizeof(recvret));
1138                 if (readlen < sizeof(recvret)) {
1139                         ERR("readlen: %zd", readlen);
1140                         PERROR("Error reading response from run_as at creation");
1141                         ret = -1;
1142                         goto error_fork;
1143                 }
1144                 global_worker = worker;
1145         }
1146 end:
1147         pthread_mutex_unlock(&worker_lock);
1148         return ret;
1149
1150         /* Error handling. */
1151 error_fork:
1152         for (i = 0; i < 2; i++) {
1153                 if (worker->sockpair[i] < 0) {
1154                         continue;
1155                 }
1156                 if (lttcomm_close_unix_sock(worker->sockpair[i])) {
1157                         PERROR("close");
1158                 }
1159                 worker->sockpair[i] = -1;
1160         }
1161 error_sock:
1162         free(worker);
1163         pthread_mutex_unlock(&worker_lock);
1164         return ret;
1165 }
1166
1167 LTTNG_HIDDEN
1168 void run_as_destroy_worker(void)
1169 {
1170         struct run_as_worker *worker = global_worker;
1171
1172         DBG("Destroying run_as worker");
1173         pthread_mutex_lock(&worker_lock);
1174         if (!worker) {
1175                 goto end;
1176         }
1177         /* Close unix socket */
1178         DBG("Closing run_as worker socket");
1179         if (lttcomm_close_unix_sock(worker->sockpair[0])) {
1180                 PERROR("close");
1181         }
1182         worker->sockpair[0] = -1;
1183         /* Wait for worker. */
1184         for (;;) {
1185                 int status;
1186                 pid_t wait_ret;
1187
1188                 wait_ret = waitpid(worker->pid, &status, 0);
1189                 if (wait_ret < 0) {
1190                         if (errno == EINTR) {
1191                                 continue;
1192                         }
1193                         PERROR("waitpid");
1194                         break;
1195                 }
1196
1197                 if (WIFEXITED(status)) {
1198                         LOG(WEXITSTATUS(status) == 0 ? PRINT_DBG : PRINT_ERR,
1199                                         DEFAULT_RUN_AS_WORKER_NAME " terminated with status code %d",
1200                                         WEXITSTATUS(status));
1201                         break;
1202                 } else if (WIFSIGNALED(status)) {
1203                         ERR(DEFAULT_RUN_AS_WORKER_NAME " was killed by signal %d",
1204                                         WTERMSIG(status));
1205                         break;
1206                 }
1207         }
1208         free(worker);
1209         global_worker = NULL;
1210 end:
1211         pthread_mutex_unlock(&worker_lock);
1212 }