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         memset(&sendret, 0, sizeof(sendret));
 492         sendret.fd = -1;
 493
 494         /*
 495          * Stage 1: Receive run_as_data struct from the master.
 496          * The structure contains the command type and all the parameters needed for
 497          * its execution
 498          */
 499         readlen = lttcomm_recv_unix_sock(worker->sockpair[1], &data,
 500                         sizeof(data));
 501         if (readlen == 0) {
 502                 /* hang up */
 503                 ret = 1;
 504                 goto end;
 505         }
 506         if (readlen < sizeof(data)) {
 507                 PERROR("lttcomm_recv_unix_sock error");
 508                 ret = -1;
 509                 goto end;
 510         }
 511
 512         cmd = run_as_enum_to_fct(data.cmd);
 513         if (!cmd) {
 514                 ret = -1;
 515                 goto end;
 516         }
 517
 518         /*
 519          * Stage 2: Receive file descriptor from master.
 520          * Some commands need a file descriptor as input so if it's needed we
 521          * receive the fd using the Unix socket.
 522          */
 523         ret = recv_fd_from_master(worker, data.cmd, &data.fd);
 524         if (ret < 0) {
 525                 PERROR("recv_fd_from_master error");
 526                 ret = -1;
 527                 goto end;
 528         }
 529
 530         prev_euid = getuid();
 531         if (data.gid != getegid()) {
 532                 ret = setegid(data.gid);
 533                 if (ret < 0) {
 534                         sendret._error = true;
 535                         sendret._errno = errno;
 536                         PERROR("setegid");
 537                         goto write_return;
 538                 }
 539         }
 540         if (data.uid != prev_euid) {
 541                 ret = seteuid(data.uid);
 542                 if (ret < 0) {
 543                         sendret._error = true;
 544                         sendret._errno = errno;
 545                         PERROR("seteuid");
 546                         goto write_return;
 547                 }
 548         }
 549
 550         /*
 551          * Also set umask to 0 for mkdir executable bit.
 552          */
 553         umask(0);
 554
 555         /*
 556          * Stage 3: Execute the command
 557          */
 558         ret = (*cmd)(&data, &sendret);
 559         if (ret < 0) {
 560                 DBG("Execution of command returned an error");
 561         }
 562
 563 write_return:
 564         ret = cleanup_received_fd(data.cmd, data.fd);
 565         if (ret < 0) {
 566                 ERR("Error cleaning up FD");
 567                 goto end;
 568         }
 569
 570         /*
 571          * Stage 4: Send run_as_ret structure to the master.
 572          * This structure contain the return value of the command and the errno.
 573          */
 574         writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
 575                         sizeof(sendret));
 576         if (writelen < sizeof(sendret)) {
 577                 PERROR("lttcomm_send_unix_sock error");
 578                 ret = -1;
 579                 goto end;
 580         }
 581
 582         /*
 583          * Stage 5: Send file descriptor to the master
 584          * Some commands return a file descriptor so if it's needed we pass it back
 585          * to the master using the Unix socket.
 586          */
 587         ret = send_fd_to_master(worker, data.cmd, sendret.fd);
 588         if (ret < 0) {
 589                 DBG("Sending FD to master returned an error");
 590                 goto end;
 591         }
 592
 593         if (seteuid(prev_euid) < 0) {
 594                 PERROR("seteuid");
 595                 ret = -1;
 596                 goto end;
 597         }
 598         ret = 0;
 599 end:
 600         return ret;
 601 }
 602
 603 static
 604 int run_as_worker(struct run_as_worker *worker)
 605 {
 606         int ret;
 607         ssize_t writelen;
 608         struct run_as_ret sendret;
 609         size_t proc_orig_len;
 610
 611         /*
 612          * Initialize worker. Set a different process cmdline.
 613          */
 614         proc_orig_len = strlen(worker->procname);
 615         memset(worker->procname, 0, proc_orig_len);
 616         strncpy(worker->procname, DEFAULT_RUN_AS_WORKER_NAME, proc_orig_len);
 617
 618         ret = lttng_prctl(PR_SET_NAME,
 619                         (unsigned long) DEFAULT_RUN_AS_WORKER_NAME, 0, 0, 0);
 620         if (ret && ret != -ENOSYS) {
 621                 /* Don't fail as this is not essential. */
 622                 PERROR("prctl PR_SET_NAME");
 623         }
 624
 625         memset(&sendret, 0, sizeof(sendret));
 626
 627         writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
 628                         sizeof(sendret));
 629         if (writelen < sizeof(sendret)) {
 630                 PERROR("lttcomm_send_unix_sock error");
 631                 ret = EXIT_FAILURE;
 632                 goto end;
 633         }
 634
 635         for (;;) {
 636                 ret = handle_one_cmd(worker);
 637                 if (ret < 0) {
 638                         ret = EXIT_FAILURE;
 639                         goto end;
 640                 } else if (ret > 0) {
 641                         break;
 642                 } else {
 643                         continue;       /* Next command. */
 644                 }
 645         }
 646         ret = EXIT_SUCCESS;
 647 end:
 648         return ret;
 649 }
 650
 651 static
 652 int run_as_cmd(struct run_as_worker *worker,
 653                 enum run_as_cmd cmd,
 654                 struct run_as_data *data,
 655                 struct run_as_ret *ret_value,
 656                 uid_t uid, gid_t gid)
 657 {
 658         int ret = 0;
 659         ssize_t readlen, writelen;
 660
 661         /*
 662          * If we are non-root, we can only deal with our own uid.
 663          */
 664         if (geteuid() != 0) {
 665                 if (uid != geteuid()) {
 666                         ret = -1;
 667                         ret_value->_errno = EPERM;
 668                         ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)",
 669                                 (int) uid, (int) geteuid());
 670                         goto end;
 671                 }
 672         }
 673
 674         data->cmd = cmd;
 675         data->uid = uid;
 676         data->gid = gid;
 677
 678         /*
 679          * Stage 1: Send the run_as_data struct to the worker process
 680          */
 681         writelen = lttcomm_send_unix_sock(worker->sockpair[0], data,
 682                         sizeof(*data));
 683         if (writelen < sizeof(*data)) {
 684                 PERROR("Error writing message to run_as");
 685                 ret = -1;
 686                 ret_value->_errno = EIO;
 687                 goto end;
 688         }
 689
 690         /*
 691          * Stage 2: Send file descriptor to the worker process if needed
 692          */
 693         ret = send_fd_to_worker(worker, data->cmd, data->fd);
 694         if (ret) {
 695                 PERROR("do_send_fd error");
 696                 ret = -1;
 697                 ret_value->_errno = EIO;
 698                 goto end;
 699         }
 700
 701         /*
 702          * Stage 3: Wait for the execution of the command
 703          */
 704
 705         /*
 706          * Stage 4: Receive the run_as_ret struct containing the return value and
 707          * errno
 708          */
 709         readlen = lttcomm_recv_unix_sock(worker->sockpair[0], ret_value,
 710                         sizeof(*ret_value));
 711         if (!readlen) {
 712                 ERR("Run-as worker has hung-up during run_as_cmd");
 713                 ret = -1;
 714                 ret_value->_errno = EIO;
 715                 goto end;
 716         } else if (readlen < sizeof(*ret_value)) {
 717                 PERROR("Error reading response from run_as");
 718                 ret = -1;
 719                 ret_value->_errno = errno;
 720                 goto end;
 721         }
 722
 723         /*
 724          * Stage 5: Receive file descriptor if needed
 725          */
 726         ret = recv_fd_from_worker(worker, data->cmd, &ret_value->fd);
 727         if (ret < 0) {
 728                 ERR("Error receiving fd");
 729                 ret = -1;
 730                 ret_value->_errno = EIO;
 731         }
 732
 733 end:
 734         return ret;
 735 }
 736
 737 /*
 738  * This is for debugging ONLY and should not be considered secure.
 739  */
 740 static
 741 int run_as_noworker(enum run_as_cmd cmd,
 742                 struct run_as_data *data, struct run_as_ret *ret_value,
 743                 uid_t uid, gid_t gid)
 744 {
 745         int ret, saved_errno;
 746         mode_t old_mask;
 747         run_as_fct fct;
 748
 749         fct = run_as_enum_to_fct(cmd);
 750         if (!fct) {
 751                 errno = -ENOSYS;
 752                 ret = -1;
 753                 goto end;
 754         }
 755         old_mask = umask(0);
 756         ret = fct(data, ret_value);
 757         saved_errno = ret_value->_errno;
 758         umask(old_mask);
 759         errno = saved_errno;
 760 end:
 761         return ret;
 762 }
 763
 764 static
 765 int run_as_restart_worker(struct run_as_worker *worker)
 766 {
 767         int ret = 0;
 768         char *procname = NULL;
 769
 770         procname = worker->procname;
 771
 772         /* Close socket to run_as worker process and clean up the zombie process */
 773         run_as_destroy_worker();
 774
 775         /* Create a new run_as worker process*/
 776         ret = run_as_create_worker(procname);
 777         if (ret < 0 ) {
 778                 ERR("Restarting the worker process failed");
 779                 ret = -1;
 780                 goto err;
 781         }
 782 err:
 783         return ret;
 784 }
 785
 786 static
 787 int run_as(enum run_as_cmd cmd, struct run_as_data *data,
 788                    struct run_as_ret *ret_value, uid_t uid, gid_t gid)
 789 {
 790         int ret, saved_errno;
 791
 792         if (use_clone()) {
 793                 DBG("Using run_as worker");
 794                 pthread_mutex_lock(&worker_lock);
 795                 assert(global_worker);
 796
 797                 ret = run_as_cmd(global_worker, cmd, data, ret_value, uid, gid);
 798                 saved_errno = ret_value->_errno;
 799
 800                 pthread_mutex_unlock(&worker_lock);
 801                 /*
 802                  * If the worker thread crashed the errno is set to EIO. we log
 803                  * the error and  start a new worker process.
 804                  */
 805                 if (ret == -1 && saved_errno == EIO) {
 806                         DBG("Socket closed unexpectedly... "
 807                                         "Restarting the worker process");
 808                         ret = run_as_restart_worker(global_worker);
 809
 810                         if (ret == -1) {
 811                                 ERR("Failed to restart worker process.");
 812                                 goto err;
 813                         }
 814                 }
 815         } else {
 816                 DBG("Using run_as without worker");
 817                 ret = run_as_noworker(cmd, data, ret_value, uid, gid);
 818         }
 819 err:
 820         return ret;
 821 }
 822
 823 LTTNG_HIDDEN
 824 int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid)
 825 {
 826         struct run_as_data data;
 827         struct run_as_ret ret;
 828
 829         memset(&data, 0, sizeof(data));
 830         memset(&ret, 0, sizeof(ret));
 831         DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d",
 832                         path, (int) mode, (int) uid, (int) gid);
 833         strncpy(data.u.mkdir.path, path, PATH_MAX - 1);
 834         data.u.mkdir.path[PATH_MAX - 1] = '\0';
 835         data.u.mkdir.mode = mode;
 836
 837         run_as(RUN_AS_MKDIR_RECURSIVE, &data, &ret, uid, gid);
 838         errno = ret._errno;
 839         return ret.u.mkdir.ret;
 840 }
 841
 842 LTTNG_HIDDEN
 843 int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid)
 844 {
 845         struct run_as_data data;
 846         struct run_as_ret ret;
 847
 848         memset(&data, 0, sizeof(data));
 849         memset(&ret, 0, sizeof(ret));
 850
 851         DBG3("mkdir() %s with mode %d for uid %d and gid %d",
 852                         path, (int) mode, (int) uid, (int) gid);
 853         strncpy(data.u.mkdir.path, path, PATH_MAX - 1);
 854         data.u.mkdir.path[PATH_MAX - 1] = '\0';
 855         data.u.mkdir.mode = mode;
 856         run_as(RUN_AS_MKDIR, &data, &ret, uid, gid);
 857         errno = ret._errno;
 858         return ret.u.mkdir.ret;
 859 }
 860
 861 LTTNG_HIDDEN
 862 int run_as_open(const char *path, int flags, mode_t mode, uid_t uid, gid_t gid)
 863 {
 864         struct run_as_data data;
 865         struct run_as_ret ret;
 866
 867         memset(&data, 0, sizeof(data));
 868         memset(&ret, 0, sizeof(ret));
 869
 870         DBG3("open() %s with flags %X mode %d for uid %d and gid %d",
 871                         path, flags, (int) mode, (int) uid, (int) gid);
 872         strncpy(data.u.open.path, path, PATH_MAX - 1);
 873         data.u.open.path[PATH_MAX - 1] = '\0';
 874         data.u.open.flags = flags;
 875         data.u.open.mode = mode;
 876         run_as(RUN_AS_OPEN, &data, &ret, uid, gid);
 877         errno = ret._errno;
 878         ret.u.open.ret = ret.fd;
 879         return ret.u.open.ret;
 880 }
 881
 882 LTTNG_HIDDEN
 883 int run_as_unlink(const char *path, uid_t uid, gid_t gid)
 884 {
 885         struct run_as_data data;
 886         struct run_as_ret ret;
 887
 888         memset(&data, 0, sizeof(data));
 889         memset(&ret, 0, sizeof(ret));
 890
 891         DBG3("unlink() %s with for uid %d and gid %d",
 892                         path, (int) uid, (int) gid);
 893         strncpy(data.u.unlink.path, path, PATH_MAX - 1);
 894         data.u.unlink.path[PATH_MAX - 1] = '\0';
 895         run_as(RUN_AS_UNLINK, &data, &ret, uid, gid);
 896         errno = ret._errno;
 897         return ret.u.unlink.ret;
 898 }
 899
 900 LTTNG_HIDDEN
 901 int run_as_rmdir_recursive(const char *path, uid_t uid, gid_t gid)
 902 {
 903         struct run_as_data data;
 904         struct run_as_ret ret;
 905
 906         memset(&data, 0, sizeof(data));
 907         memset(&ret, 0, sizeof(ret));
 908
 909         DBG3("rmdir_recursive() %s with for uid %d and gid %d",
 910                         path, (int) uid, (int) gid);
 911         strncpy(data.u.rmdir_recursive.path, path, PATH_MAX - 1);
 912         data.u.rmdir_recursive.path[PATH_MAX - 1] = '\0';
 913         run_as(RUN_AS_RMDIR_RECURSIVE, &data, &ret, uid, gid);
 914         errno = ret._errno;
 915         return ret.u.rmdir_recursive.ret;
 916 }
 917
 918 LTTNG_HIDDEN
 919 int run_as_extract_elf_symbol_offset(int fd, const char* function,
 920                 uid_t uid, gid_t gid, uint64_t *offset)
 921 {
 922         struct run_as_data data;
 923         struct run_as_ret ret;
 924
 925         memset(&data, 0, sizeof(data));
 926         memset(&ret, 0, sizeof(ret));
 927
 928         DBG3("extract_elf_symbol_offset() on fd=%d and function=%s "
 929                 "with for uid %d and gid %d", fd, function, (int) uid, (int) gid);
 930
 931         data.fd = fd;
 932
 933         strncpy(data.u.extract_elf_symbol_offset.function, function, LTTNG_SYMBOL_NAME_LEN - 1);
 934
 935         data.u.extract_elf_symbol_offset.function[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 936
 937         run_as(RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET, &data, &ret, uid, gid);
 938
 939         errno = ret._errno;
 940
 941         if (ret._error) {
 942                 return -1;
 943         }
 944
 945         *offset = ret.u.extract_elf_symbol_offset.offset;
 946         return 0;
 947 }
 948
 949 LTTNG_HIDDEN
 950 int run_as_extract_sdt_probe_offsets(int fd, const char* provider_name,
 951                 const char* probe_name, uid_t uid, gid_t gid,
 952                 uint64_t **offsets, uint32_t *num_offset)
 953 {
 954         struct run_as_data data;
 955         struct run_as_ret ret;
 956
 957         memset(&data, 0, sizeof(data));
 958         memset(&ret, 0, sizeof(ret));
 959
 960         DBG3("extract_sdt_probe_offsets() on fd=%d, probe_name=%s and "
 961                 "provider_name=%s with for uid %d and gid %d", fd, probe_name,
 962                 provider_name, (int) uid, (int) gid);
 963
 964         data.fd = fd;
 965
 966         strncpy(data.u.extract_sdt_probe_offsets.probe_name, probe_name, LTTNG_SYMBOL_NAME_LEN - 1);
 967         strncpy(data.u.extract_sdt_probe_offsets.provider_name, provider_name, LTTNG_SYMBOL_NAME_LEN - 1);
 968
 969         data.u.extract_sdt_probe_offsets.probe_name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 970         data.u.extract_sdt_probe_offsets.provider_name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 971
 972         run_as(RUN_AS_EXTRACT_SDT_PROBE_OFFSETS, &data, &ret, uid, gid);
 973
 974         errno = ret._errno;
 975
 976         if (ret._error) {
 977                 return -1;
 978         }
 979
 980         *num_offset = ret.u.extract_sdt_probe_offsets.num_offset;
 981
 982         *offsets = zmalloc(*num_offset * sizeof(uint64_t));
 983         if (!*offsets) {
 984                 return -ENOMEM;
 985         }
 986
 987         memcpy(*offsets, ret.u.extract_sdt_probe_offsets.offsets, *num_offset * sizeof(uint64_t));
 988         return 0;
 989 }
 990
 991 static
 992 int reset_sighandler(void)
 993 {
 994         int sig;
 995
 996         DBG("Resetting run_as worker signal handlers to default");
 997         for (sig = 1; sig <= 31; sig++) {
 998                 (void) signal(sig, SIG_DFL);
 999         }
1000         return 0;
1001 }
1002
1003 static
1004 void worker_sighandler(int sig)
1005 {
1006         const char *signame;
1007
1008         /*
1009          * The worker will inherit its parent's signals since they are part of
1010          * the same process group. However, in the case of SIGINT and SIGTERM,
1011          * we want to give the worker a chance to teardown gracefully when its
1012          * parent closes the command socket.
1013          */
1014         switch (sig) {
1015         case SIGINT:
1016                 signame = "SIGINT";
1017                 break;
1018         case SIGTERM:
1019                 signame = "SIGTERM";
1020                 break;
1021         default:
1022                 signame = NULL;
1023         }
1024
1025         if (signame) {
1026                 DBG("run_as worker received signal %s", signame);
1027         } else {
1028                 DBG("run_as_worker received signal %d", sig);
1029         }
1030 }
1031
1032 static
1033 int set_worker_sighandlers(void)
1034 {
1035         int ret = 0;
1036         sigset_t sigset;
1037         struct sigaction sa;
1038
1039         if ((ret = sigemptyset(&sigset)) < 0) {
1040                 PERROR("sigemptyset");
1041                 goto end;
1042         }
1043
1044         sa.sa_handler = worker_sighandler;
1045         sa.sa_mask = sigset;
1046         sa.sa_flags = 0;
1047         if ((ret = sigaction(SIGINT, &sa, NULL)) < 0) {
1048                 PERROR("sigaction SIGINT");
1049                 goto end;
1050         }
1051
1052         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
1053                 PERROR("sigaction SIGTERM");
1054                 goto end;
1055         }
1056
1057         DBG("run_as signal handler set for SIGTERM and SIGINT");
1058 end:
1059         return ret;
1060 }
1061
1062 LTTNG_HIDDEN
1063 int run_as_create_worker(char *procname)
1064 {
1065         pid_t pid;
1066         int i, ret = 0;
1067         ssize_t readlen;
1068         struct run_as_ret recvret;
1069         struct run_as_worker *worker;
1070
1071         pthread_mutex_lock(&worker_lock);
1072         assert(!global_worker);
1073         if (!use_clone()) {
1074                 /*
1075                  * Don't initialize a worker, all run_as tasks will be performed
1076                  * in the current process.
1077                  */
1078                 ret = 0;
1079                 goto end;
1080         }
1081         worker = zmalloc(sizeof(*worker));
1082         if (!worker) {
1083                 ret = -ENOMEM;
1084                 goto end;
1085         }
1086         worker->procname = procname;
1087         /* Create unix socket. */
1088         if (lttcomm_create_anon_unix_socketpair(worker->sockpair) < 0) {
1089                 ret = -1;
1090                 goto error_sock;
1091         }
1092
1093         /* Fork worker. */
1094         pid = fork();
1095         if (pid < 0) {
1096                 PERROR("fork");
1097                 ret = -1;
1098                 goto error_fork;
1099         } else if (pid == 0) {
1100                 /* Child */
1101
1102                 reset_sighandler();
1103
1104                 set_worker_sighandlers();
1105
1106                 /* The child has no use for this lock. */
1107                 pthread_mutex_unlock(&worker_lock);
1108                 /* Just close, no shutdown. */
1109                 if (close(worker->sockpair[0])) {
1110                         PERROR("close");
1111                         exit(EXIT_FAILURE);
1112                 }
1113
1114                 /*
1115                  * Close all FDs aside from STDIN, STDOUT, STDERR and sockpair[1]
1116                  * Sockpair[1] is used as a control channel with the master
1117                  */
1118                 for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) {
1119                         if (i != worker->sockpair[1]) {
1120                                 (void) close(i);
1121                         }
1122                 }
1123
1124                 worker->sockpair[0] = -1;
1125                 ret = run_as_worker(worker);
1126                 if (lttcomm_close_unix_sock(worker->sockpair[1])) {
1127                         PERROR("close");
1128                         ret = -1;
1129                 }
1130                 worker->sockpair[1] = -1;
1131                 LOG(ret ? PRINT_ERR : PRINT_DBG, "run_as worker exiting (ret = %d)", ret);
1132                 exit(ret ? EXIT_FAILURE : EXIT_SUCCESS);
1133         } else {
1134                 /* Parent */
1135
1136                 /* Just close, no shutdown. */
1137                 if (close(worker->sockpair[1])) {
1138                         PERROR("close");
1139                         ret = -1;
1140                         goto error_fork;
1141                 }
1142                 worker->sockpair[1] = -1;
1143                 worker->pid = pid;
1144                 /* Wait for worker to become ready. */
1145                 readlen = lttcomm_recv_unix_sock(worker->sockpair[0],
1146                                 &recvret, sizeof(recvret));
1147                 if (readlen < sizeof(recvret)) {
1148                         ERR("readlen: %zd", readlen);
1149                         PERROR("Error reading response from run_as at creation");
1150                         ret = -1;
1151                         goto error_fork;
1152                 }
1153                 global_worker = worker;
1154         }
1155 end:
1156         pthread_mutex_unlock(&worker_lock);
1157         return ret;
1158
1159         /* Error handling. */
1160 error_fork:
1161         for (i = 0; i < 2; i++) {
1162                 if (worker->sockpair[i] < 0) {
1163                         continue;
1164                 }
1165                 if (lttcomm_close_unix_sock(worker->sockpair[i])) {
1166                         PERROR("close");
1167                 }
1168                 worker->sockpair[i] = -1;
1169         }
1170 error_sock:
1171         free(worker);
1172         pthread_mutex_unlock(&worker_lock);
1173         return ret;
1174 }
1175
1176 LTTNG_HIDDEN
1177 void run_as_destroy_worker(void)
1178 {
1179         struct run_as_worker *worker = global_worker;
1180
1181         DBG("Destroying run_as worker");
1182         pthread_mutex_lock(&worker_lock);
1183         if (!worker) {
1184                 goto end;
1185         }
1186         /* Close unix socket */
1187         DBG("Closing run_as worker socket");
1188         if (lttcomm_close_unix_sock(worker->sockpair[0])) {
1189                 PERROR("close");
1190         }
1191         worker->sockpair[0] = -1;
1192         /* Wait for worker. */
1193         for (;;) {
1194                 int status;
1195                 pid_t wait_ret;
1196
1197                 wait_ret = waitpid(worker->pid, &status, 0);
1198                 if (wait_ret < 0) {
1199                         if (errno == EINTR) {
1200                                 continue;
1201                         }
1202                         PERROR("waitpid");
1203                         break;
1204                 }
1205
1206                 if (WIFEXITED(status)) {
1207                         LOG(WEXITSTATUS(status) == 0 ? PRINT_DBG : PRINT_ERR,
1208                                         DEFAULT_RUN_AS_WORKER_NAME " terminated with status code %d",
1209                                         WEXITSTATUS(status));
1210                         break;
1211                 } else if (WIFSIGNALED(status)) {
1212                         ERR(DEFAULT_RUN_AS_WORKER_NAME " was killed by signal %d",
1213                                         WTERMSIG(status));
1214                         break;
1215                 }
1216         }
1217         free(worker);
1218         global_worker = NULL;
1219 end:
1220         pthread_mutex_unlock(&worker_lock);
1221 }