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("Attempt to send invalid file descriptor to master (fd = %i)", fd);
 333                 /* Return 0 as this is not a fatal error. */
 334                 return 0;
 335         }
 336
 337         len = lttcomm_send_fds_unix_sock(sock, &fd, 1);
 338         if (len < 0) {
 339                 PERROR("lttcomm_send_fds_unix_sock");
 340                 return -1;
 341         }
 342         return 0;
 343 }
 344
 345 static
 346 int do_recv_fd(int sock, int *fd)
 347 {
 348         ssize_t len;
 349
 350         len = lttcomm_recv_fds_unix_sock(sock, fd, 1);
 351
 352         if (!len) {
 353                 return -1;
 354         } else if (len < 0) {
 355                 PERROR("lttcomm_recv_fds_unix_sock");
 356                 return -1;
 357         }
 358         if (*fd < 0) {
 359                 ERR("Invalid file descriptor received from worker (fd = %i)", *fd);
 360                 /* Return 0 as this is not a fatal error. */
 361                 return 0;
 362         }
 363
 364         return 0;
 365 }
 366
 367 static
 368 int send_fd_to_worker(struct run_as_worker *worker, enum run_as_cmd cmd, int fd)
 369 {
 370         int ret = 0;
 371
 372         switch (cmd) {
 373         case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET:
 374         case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS:
 375                 break;
 376         default:
 377                 return 0;
 378         }
 379
 380         if (fd < 0) {
 381                 ERR("Refusing to send invalid fd to worker (fd = %i)", fd);
 382                 return -1;
 383         }
 384
 385         ret = do_send_fd(worker->sockpair[0], fd);
 386         if (ret < 0) {
 387                 PERROR("do_send_fd");
 388                 ret = -1;
 389         }
 390
 391         return ret;
 392 }
 393
 394 static
 395 int send_fd_to_master(struct run_as_worker *worker, enum run_as_cmd cmd, int fd)
 396 {
 397         int ret = 0, ret_close = 0;
 398
 399         switch (cmd) {
 400         case RUN_AS_OPEN:
 401                 break;
 402         default:
 403                 return 0;
 404         }
 405
 406         if (fd < 0) {
 407                 DBG("Not sending file descriptor to master as it is invalid (fd = %i)", fd);
 408                 return 0;
 409         }
 410         ret = do_send_fd(worker->sockpair[1], fd);
 411         if (ret < 0) {
 412                 PERROR("do_send_fd error");
 413                 ret = -1;
 414         }
 415
 416         ret_close = close(fd);
 417         if (ret_close < 0) {
 418                 PERROR("close");
 419         }
 420
 421         return ret;
 422 }
 423
 424 static
 425 int recv_fd_from_worker(struct run_as_worker *worker, enum run_as_cmd cmd, int *fd)
 426 {
 427         int ret = 0;
 428
 429         switch (cmd) {
 430         case RUN_AS_OPEN:
 431                 break;
 432         default:
 433                 return 0;
 434         }
 435
 436         ret = do_recv_fd(worker->sockpair[0], fd);
 437         if (ret < 0) {
 438                 PERROR("do_recv_fd error");
 439                 ret = -1;
 440         }
 441
 442         return ret;
 443 }
 444
 445 static
 446 int recv_fd_from_master(struct run_as_worker *worker, enum run_as_cmd cmd, int *fd)
 447 {
 448         int ret = 0;
 449
 450         switch (cmd) {
 451         case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET:
 452         case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS:
 453                 break;
 454         default:
 455                 return 0;
 456         }
 457
 458         ret = do_recv_fd(worker->sockpair[1], fd);
 459         if (ret < 0) {
 460                 PERROR("do_recv_fd error");
 461                 ret = -1;
 462         }
 463
 464         return ret;
 465 }
 466
 467 static
 468 int cleanup_received_fd(enum run_as_cmd cmd, int fd)
 469 {
 470         int ret = 0;
 471
 472         switch (cmd) {
 473         case RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET:
 474         case RUN_AS_EXTRACT_SDT_PROBE_OFFSETS:
 475                 break;
 476         default:
 477                 return 0;
 478         }
 479
 480         if (fd < 0) {
 481                 return 0;
 482         }
 483         ret = close(fd);
 484         if (ret < 0) {
 485                 PERROR("close error");
 486                 ret = -1;
 487         }
 488
 489         return ret;
 490 }
 491
 492 /*
 493  * Return < 0 on error, 0 if OK, 1 on hangup.
 494  */
 495 static
 496 int handle_one_cmd(struct run_as_worker *worker)
 497 {
 498         int ret = 0;
 499         struct run_as_data data;
 500         ssize_t readlen, writelen;
 501         struct run_as_ret sendret;
 502         run_as_fct cmd;
 503         uid_t prev_euid;
 504
 505         memset(&sendret, 0, sizeof(sendret));
 506         sendret.fd = -1;
 507
 508         /*
 509          * Stage 1: Receive run_as_data struct from the master.
 510          * The structure contains the command type and all the parameters needed for
 511          * its execution
 512          */
 513         readlen = lttcomm_recv_unix_sock(worker->sockpair[1], &data,
 514                         sizeof(data));
 515         if (readlen == 0) {
 516                 /* hang up */
 517                 ret = 1;
 518                 goto end;
 519         }
 520         if (readlen < sizeof(data)) {
 521                 PERROR("lttcomm_recv_unix_sock error");
 522                 ret = -1;
 523                 goto end;
 524         }
 525
 526         cmd = run_as_enum_to_fct(data.cmd);
 527         if (!cmd) {
 528                 ret = -1;
 529                 goto end;
 530         }
 531
 532         /*
 533          * Stage 2: Receive file descriptor from master.
 534          * Some commands need a file descriptor as input so if it's needed we
 535          * receive the fd using the Unix socket.
 536          */
 537         ret = recv_fd_from_master(worker, data.cmd, &data.fd);
 538         if (ret < 0) {
 539                 PERROR("recv_fd_from_master error");
 540                 ret = -1;
 541                 goto end;
 542         }
 543
 544         prev_euid = getuid();
 545         if (data.gid != getegid()) {
 546                 ret = setegid(data.gid);
 547                 if (ret < 0) {
 548                         sendret._error = true;
 549                         sendret._errno = errno;
 550                         PERROR("setegid");
 551                         goto write_return;
 552                 }
 553         }
 554         if (data.uid != prev_euid) {
 555                 ret = seteuid(data.uid);
 556                 if (ret < 0) {
 557                         sendret._error = true;
 558                         sendret._errno = errno;
 559                         PERROR("seteuid");
 560                         goto write_return;
 561                 }
 562         }
 563
 564         /*
 565          * Also set umask to 0 for mkdir executable bit.
 566          */
 567         umask(0);
 568
 569         /*
 570          * Stage 3: Execute the command
 571          */
 572         ret = (*cmd)(&data, &sendret);
 573         if (ret < 0) {
 574                 DBG("Execution of command returned an error");
 575         }
 576
 577 write_return:
 578         ret = cleanup_received_fd(data.cmd, data.fd);
 579         if (ret < 0) {
 580                 ERR("Error cleaning up FD");
 581                 goto end;
 582         }
 583
 584         /*
 585          * Stage 4: Send run_as_ret structure to the master.
 586          * This structure contain the return value of the command and the errno.
 587          */
 588         writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
 589                         sizeof(sendret));
 590         if (writelen < sizeof(sendret)) {
 591                 PERROR("lttcomm_send_unix_sock error");
 592                 ret = -1;
 593                 goto end;
 594         }
 595
 596         /*
 597          * Stage 5: Send file descriptor to the master
 598          * Some commands return a file descriptor so if it's needed we pass it back
 599          * to the master using the Unix socket.
 600          */
 601         ret = send_fd_to_master(worker, data.cmd, sendret.fd);
 602         if (ret < 0) {
 603                 DBG("Sending FD to master returned an error");
 604                 goto end;
 605         }
 606
 607         if (seteuid(prev_euid) < 0) {
 608                 PERROR("seteuid");
 609                 ret = -1;
 610                 goto end;
 611         }
 612         ret = 0;
 613 end:
 614         return ret;
 615 }
 616
 617 static
 618 int run_as_worker(struct run_as_worker *worker)
 619 {
 620         int ret;
 621         ssize_t writelen;
 622         struct run_as_ret sendret;
 623         size_t proc_orig_len;
 624
 625         /*
 626          * Initialize worker. Set a different process cmdline.
 627          */
 628         proc_orig_len = strlen(worker->procname);
 629         memset(worker->procname, 0, proc_orig_len);
 630         strncpy(worker->procname, DEFAULT_RUN_AS_WORKER_NAME, proc_orig_len);
 631
 632         ret = lttng_prctl(PR_SET_NAME,
 633                         (unsigned long) DEFAULT_RUN_AS_WORKER_NAME, 0, 0, 0);
 634         if (ret && ret != -ENOSYS) {
 635                 /* Don't fail as this is not essential. */
 636                 PERROR("prctl PR_SET_NAME");
 637         }
 638
 639         memset(&sendret, 0, sizeof(sendret));
 640
 641         writelen = lttcomm_send_unix_sock(worker->sockpair[1], &sendret,
 642                         sizeof(sendret));
 643         if (writelen < sizeof(sendret)) {
 644                 PERROR("lttcomm_send_unix_sock error");
 645                 ret = EXIT_FAILURE;
 646                 goto end;
 647         }
 648
 649         for (;;) {
 650                 ret = handle_one_cmd(worker);
 651                 if (ret < 0) {
 652                         ret = EXIT_FAILURE;
 653                         goto end;
 654                 } else if (ret > 0) {
 655                         break;
 656                 } else {
 657                         continue;       /* Next command. */
 658                 }
 659         }
 660         ret = EXIT_SUCCESS;
 661 end:
 662         return ret;
 663 }
 664
 665 static
 666 int run_as_cmd(struct run_as_worker *worker,
 667                 enum run_as_cmd cmd,
 668                 struct run_as_data *data,
 669                 struct run_as_ret *ret_value,
 670                 uid_t uid, gid_t gid)
 671 {
 672         int ret = 0;
 673         ssize_t readlen, writelen;
 674
 675         /*
 676          * If we are non-root, we can only deal with our own uid.
 677          */
 678         if (geteuid() != 0) {
 679                 if (uid != geteuid()) {
 680                         ret = -1;
 681                         ret_value->_errno = EPERM;
 682                         ERR("Client (%d)/Server (%d) UID mismatch (and sessiond is not root)",
 683                                 (int) uid, (int) geteuid());
 684                         goto end;
 685                 }
 686         }
 687
 688         data->cmd = cmd;
 689         data->uid = uid;
 690         data->gid = gid;
 691
 692         /*
 693          * Stage 1: Send the run_as_data struct to the worker process
 694          */
 695         writelen = lttcomm_send_unix_sock(worker->sockpair[0], data,
 696                         sizeof(*data));
 697         if (writelen < sizeof(*data)) {
 698                 PERROR("Error writing message to run_as");
 699                 ret = -1;
 700                 ret_value->_errno = EIO;
 701                 goto end;
 702         }
 703
 704         /*
 705          * Stage 2: Send file descriptor to the worker process if needed
 706          */
 707         ret = send_fd_to_worker(worker, data->cmd, data->fd);
 708         if (ret) {
 709                 PERROR("do_send_fd error");
 710                 ret = -1;
 711                 ret_value->_errno = EIO;
 712                 goto end;
 713         }
 714
 715         /*
 716          * Stage 3: Wait for the execution of the command
 717          */
 718
 719         /*
 720          * Stage 4: Receive the run_as_ret struct containing the return value and
 721          * errno
 722          */
 723         readlen = lttcomm_recv_unix_sock(worker->sockpair[0], ret_value,
 724                         sizeof(*ret_value));
 725         if (!readlen) {
 726                 ERR("Run-as worker has hung-up during run_as_cmd");
 727                 ret = -1;
 728                 ret_value->_errno = EIO;
 729                 goto end;
 730         } else if (readlen < sizeof(*ret_value)) {
 731                 PERROR("Error reading response from run_as");
 732                 ret = -1;
 733                 ret_value->_errno = errno;
 734                 goto end;
 735         }
 736
 737         if (ret_value->_error) {
 738                 /* Skip stage 5 on error as there will be no fd to receive. */
 739                 goto end;
 740         }
 741
 742         /*
 743          * Stage 5: Receive file descriptor if needed
 744          */
 745         ret = recv_fd_from_worker(worker, data->cmd, &ret_value->fd);
 746         if (ret < 0) {
 747                 ERR("Error receiving fd");
 748                 ret = -1;
 749                 ret_value->_errno = EIO;
 750         }
 751
 752 end:
 753         return ret;
 754 }
 755
 756 /*
 757  * This is for debugging ONLY and should not be considered secure.
 758  */
 759 static
 760 int run_as_noworker(enum run_as_cmd cmd,
 761                 struct run_as_data *data, struct run_as_ret *ret_value,
 762                 uid_t uid, gid_t gid)
 763 {
 764         int ret, saved_errno;
 765         mode_t old_mask;
 766         run_as_fct fct;
 767
 768         fct = run_as_enum_to_fct(cmd);
 769         if (!fct) {
 770                 errno = -ENOSYS;
 771                 ret = -1;
 772                 goto end;
 773         }
 774         old_mask = umask(0);
 775         ret = fct(data, ret_value);
 776         saved_errno = ret_value->_errno;
 777         umask(old_mask);
 778         errno = saved_errno;
 779 end:
 780         return ret;
 781 }
 782
 783 static
 784 int run_as_restart_worker(struct run_as_worker *worker)
 785 {
 786         int ret = 0;
 787         char *procname = NULL;
 788
 789         procname = worker->procname;
 790
 791         /* Close socket to run_as worker process and clean up the zombie process */
 792         run_as_destroy_worker();
 793
 794         /* Create a new run_as worker process*/
 795         ret = run_as_create_worker(procname);
 796         if (ret < 0 ) {
 797                 ERR("Restarting the worker process failed");
 798                 ret = -1;
 799                 goto err;
 800         }
 801 err:
 802         return ret;
 803 }
 804
 805 static
 806 int run_as(enum run_as_cmd cmd, struct run_as_data *data,
 807                    struct run_as_ret *ret_value, uid_t uid, gid_t gid)
 808 {
 809         int ret, saved_errno;
 810
 811         if (use_clone()) {
 812                 DBG("Using run_as worker");
 813                 pthread_mutex_lock(&worker_lock);
 814                 assert(global_worker);
 815
 816                 ret = run_as_cmd(global_worker, cmd, data, ret_value, uid, gid);
 817                 saved_errno = ret_value->_errno;
 818
 819                 pthread_mutex_unlock(&worker_lock);
 820                 /*
 821                  * If the worker thread crashed the errno is set to EIO. we log
 822                  * the error and  start a new worker process.
 823                  */
 824                 if (ret == -1 && saved_errno == EIO) {
 825                         DBG("Socket closed unexpectedly... "
 826                                         "Restarting the worker process");
 827                         ret = run_as_restart_worker(global_worker);
 828                         if (ret == -1) {
 829                                 ERR("Failed to restart worker process.");
 830                                 goto err;
 831                         }
 832                 }
 833         } else {
 834                 DBG("Using run_as without worker");
 835                 ret = run_as_noworker(cmd, data, ret_value, uid, gid);
 836         }
 837 err:
 838         return ret;
 839 }
 840
 841 LTTNG_HIDDEN
 842 int run_as_mkdir_recursive(const char *path, mode_t mode, uid_t uid, gid_t gid)
 843 {
 844         struct run_as_data data;
 845         struct run_as_ret ret;
 846
 847         memset(&data, 0, sizeof(data));
 848         memset(&ret, 0, sizeof(ret));
 849         DBG3("mkdir() recursive %s with mode %d for uid %d and gid %d",
 850                         path, (int) mode, (int) uid, (int) gid);
 851         strncpy(data.u.mkdir.path, path, PATH_MAX - 1);
 852         data.u.mkdir.path[PATH_MAX - 1] = '\0';
 853         data.u.mkdir.mode = mode;
 854
 855         run_as(RUN_AS_MKDIR_RECURSIVE, &data, &ret, uid, gid);
 856         errno = ret._errno;
 857         return ret.u.mkdir.ret;
 858 }
 859
 860 LTTNG_HIDDEN
 861 int run_as_mkdir(const char *path, mode_t mode, uid_t uid, gid_t gid)
 862 {
 863         struct run_as_data data;
 864         struct run_as_ret ret;
 865
 866         memset(&data, 0, sizeof(data));
 867         memset(&ret, 0, sizeof(ret));
 868
 869         DBG3("mkdir() %s with mode %d for uid %d and gid %d",
 870                         path, (int) mode, (int) uid, (int) gid);
 871         strncpy(data.u.mkdir.path, path, PATH_MAX - 1);
 872         data.u.mkdir.path[PATH_MAX - 1] = '\0';
 873         data.u.mkdir.mode = mode;
 874         run_as(RUN_AS_MKDIR, &data, &ret, uid, gid);
 875         errno = ret._errno;
 876         return ret.u.mkdir.ret;
 877 }
 878
 879 LTTNG_HIDDEN
 880 int run_as_open(const char *path, int flags, mode_t mode, 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("open() %s with flags %X mode %d for uid %d and gid %d",
 889                         path, flags, (int) mode, (int) uid, (int) gid);
 890         strncpy(data.u.open.path, path, PATH_MAX - 1);
 891         data.u.open.path[PATH_MAX - 1] = '\0';
 892         data.u.open.flags = flags;
 893         data.u.open.mode = mode;
 894         run_as(RUN_AS_OPEN, &data, &ret, uid, gid);
 895         errno = ret._errno;
 896         ret.u.open.ret = ret.fd;
 897         return ret.u.open.ret;
 898 }
 899
 900 LTTNG_HIDDEN
 901 int run_as_unlink(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("unlink() %s with for uid %d and gid %d",
 910                         path, (int) uid, (int) gid);
 911         strncpy(data.u.unlink.path, path, PATH_MAX - 1);
 912         data.u.unlink.path[PATH_MAX - 1] = '\0';
 913         run_as(RUN_AS_UNLINK, &data, &ret, uid, gid);
 914         errno = ret._errno;
 915         return ret.u.unlink.ret;
 916 }
 917
 918 LTTNG_HIDDEN
 919 int run_as_rmdir_recursive(const char *path, uid_t uid, gid_t gid)
 920 {
 921         struct run_as_data data;
 922         struct run_as_ret ret;
 923
 924         memset(&data, 0, sizeof(data));
 925         memset(&ret, 0, sizeof(ret));
 926
 927         DBG3("rmdir_recursive() %s with for uid %d and gid %d",
 928                         path, (int) uid, (int) gid);
 929         strncpy(data.u.rmdir_recursive.path, path, PATH_MAX - 1);
 930         data.u.rmdir_recursive.path[PATH_MAX - 1] = '\0';
 931         run_as(RUN_AS_RMDIR_RECURSIVE, &data, &ret, uid, gid);
 932         errno = ret._errno;
 933         return ret.u.rmdir_recursive.ret;
 934 }
 935
 936 LTTNG_HIDDEN
 937 int run_as_extract_elf_symbol_offset(int fd, const char* function,
 938                 uid_t uid, gid_t gid, uint64_t *offset)
 939 {
 940         struct run_as_data data;
 941         struct run_as_ret ret;
 942
 943         memset(&data, 0, sizeof(data));
 944         memset(&ret, 0, sizeof(ret));
 945
 946         DBG3("extract_elf_symbol_offset() on fd=%d and function=%s "
 947                 "with for uid %d and gid %d", fd, function, (int) uid, (int) gid);
 948
 949         data.fd = fd;
 950
 951         strncpy(data.u.extract_elf_symbol_offset.function, function, LTTNG_SYMBOL_NAME_LEN - 1);
 952
 953         data.u.extract_elf_symbol_offset.function[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 954
 955         run_as(RUN_AS_EXTRACT_ELF_SYMBOL_OFFSET, &data, &ret, uid, gid);
 956
 957         errno = ret._errno;
 958
 959         if (ret._error) {
 960                 return -1;
 961         }
 962
 963         *offset = ret.u.extract_elf_symbol_offset.offset;
 964         return 0;
 965 }
 966
 967 LTTNG_HIDDEN
 968 int run_as_extract_sdt_probe_offsets(int fd, const char* provider_name,
 969                 const char* probe_name, uid_t uid, gid_t gid,
 970                 uint64_t **offsets, uint32_t *num_offset)
 971 {
 972         struct run_as_data data;
 973         struct run_as_ret ret;
 974
 975         memset(&data, 0, sizeof(data));
 976         memset(&ret, 0, sizeof(ret));
 977
 978         DBG3("extract_sdt_probe_offsets() on fd=%d, probe_name=%s and "
 979                 "provider_name=%s with for uid %d and gid %d", fd, probe_name,
 980                 provider_name, (int) uid, (int) gid);
 981
 982         data.fd = fd;
 983
 984         strncpy(data.u.extract_sdt_probe_offsets.probe_name, probe_name, LTTNG_SYMBOL_NAME_LEN - 1);
 985         strncpy(data.u.extract_sdt_probe_offsets.provider_name, provider_name, LTTNG_SYMBOL_NAME_LEN - 1);
 986
 987         data.u.extract_sdt_probe_offsets.probe_name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 988         data.u.extract_sdt_probe_offsets.provider_name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
 989
 990         run_as(RUN_AS_EXTRACT_SDT_PROBE_OFFSETS, &data, &ret, uid, gid);
 991
 992         errno = ret._errno;
 993
 994         if (ret._error) {
 995                 return -1;
 996         }
 997
 998         *num_offset = ret.u.extract_sdt_probe_offsets.num_offset;
 999
1000         *offsets = zmalloc(*num_offset * sizeof(uint64_t));
1001         if (!*offsets) {
1002                 return -ENOMEM;
1003         }
1004
1005         memcpy(*offsets, ret.u.extract_sdt_probe_offsets.offsets, *num_offset * sizeof(uint64_t));
1006         return 0;
1007 }
1008
1009 static
1010 int reset_sighandler(void)
1011 {
1012         int sig;
1013
1014         DBG("Resetting run_as worker signal handlers to default");
1015         for (sig = 1; sig <= 31; sig++) {
1016                 (void) signal(sig, SIG_DFL);
1017         }
1018         return 0;
1019 }
1020
1021 static
1022 void worker_sighandler(int sig)
1023 {
1024         const char *signame;
1025
1026         /*
1027          * The worker will inherit its parent's signals since they are part of
1028          * the same process group. However, in the case of SIGINT and SIGTERM,
1029          * we want to give the worker a chance to teardown gracefully when its
1030          * parent closes the command socket.
1031          */
1032         switch (sig) {
1033         case SIGINT:
1034                 signame = "SIGINT";
1035                 break;
1036         case SIGTERM:
1037                 signame = "SIGTERM";
1038                 break;
1039         default:
1040                 signame = NULL;
1041         }
1042
1043         if (signame) {
1044                 DBG("run_as worker received signal %s", signame);
1045         } else {
1046                 DBG("run_as_worker received signal %d", sig);
1047         }
1048 }
1049
1050 static
1051 int set_worker_sighandlers(void)
1052 {
1053         int ret = 0;
1054         sigset_t sigset;
1055         struct sigaction sa;
1056
1057         if ((ret = sigemptyset(&sigset)) < 0) {
1058                 PERROR("sigemptyset");
1059                 goto end;
1060         }
1061
1062         sa.sa_handler = worker_sighandler;
1063         sa.sa_mask = sigset;
1064         sa.sa_flags = 0;
1065         if ((ret = sigaction(SIGINT, &sa, NULL)) < 0) {
1066                 PERROR("sigaction SIGINT");
1067                 goto end;
1068         }
1069
1070         if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
1071                 PERROR("sigaction SIGTERM");
1072                 goto end;
1073         }
1074
1075         DBG("run_as signal handler set for SIGTERM and SIGINT");
1076 end:
1077         return ret;
1078 }
1079
1080 LTTNG_HIDDEN
1081 int run_as_create_worker(char *procname)
1082 {
1083         pid_t pid;
1084         int i, ret = 0;
1085         ssize_t readlen;
1086         struct run_as_ret recvret;
1087         struct run_as_worker *worker;
1088
1089         pthread_mutex_lock(&worker_lock);
1090         assert(!global_worker);
1091         if (!use_clone()) {
1092                 /*
1093                  * Don't initialize a worker, all run_as tasks will be performed
1094                  * in the current process.
1095                  */
1096                 ret = 0;
1097                 goto end;
1098         }
1099         worker = zmalloc(sizeof(*worker));
1100         if (!worker) {
1101                 ret = -ENOMEM;
1102                 goto end;
1103         }
1104         worker->procname = procname;
1105         /* Create unix socket. */
1106         if (lttcomm_create_anon_unix_socketpair(worker->sockpair) < 0) {
1107                 ret = -1;
1108                 goto error_sock;
1109         }
1110
1111         /* Fork worker. */
1112         pid = fork();
1113         if (pid < 0) {
1114                 PERROR("fork");
1115                 ret = -1;
1116                 goto error_fork;
1117         } else if (pid == 0) {
1118                 /* Child */
1119
1120                 reset_sighandler();
1121
1122                 set_worker_sighandlers();
1123
1124                 /* The child has no use for this lock. */
1125                 pthread_mutex_unlock(&worker_lock);
1126                 /* Just close, no shutdown. */
1127                 if (close(worker->sockpair[0])) {
1128                         PERROR("close");
1129                         exit(EXIT_FAILURE);
1130                 }
1131
1132                 /*
1133                  * Close all FDs aside from STDIN, STDOUT, STDERR and sockpair[1]
1134                  * Sockpair[1] is used as a control channel with the master
1135                  */
1136                 for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) {
1137                         if (i != worker->sockpair[1]) {
1138                                 (void) close(i);
1139                         }
1140                 }
1141
1142                 worker->sockpair[0] = -1;
1143                 ret = run_as_worker(worker);
1144                 if (lttcomm_close_unix_sock(worker->sockpair[1])) {
1145                         PERROR("close");
1146                         ret = -1;
1147                 }
1148                 worker->sockpair[1] = -1;
1149                 LOG(ret ? PRINT_ERR : PRINT_DBG, "run_as worker exiting (ret = %d)", ret);
1150                 exit(ret ? EXIT_FAILURE : EXIT_SUCCESS);
1151         } else {
1152                 /* Parent */
1153
1154                 /* Just close, no shutdown. */
1155                 if (close(worker->sockpair[1])) {
1156                         PERROR("close");
1157                         ret = -1;
1158                         goto error_fork;
1159                 }
1160                 worker->sockpair[1] = -1;
1161                 worker->pid = pid;
1162                 /* Wait for worker to become ready. */
1163                 readlen = lttcomm_recv_unix_sock(worker->sockpair[0],
1164                                 &recvret, sizeof(recvret));
1165                 if (readlen < sizeof(recvret)) {
1166                         ERR("readlen: %zd", readlen);
1167                         PERROR("Error reading response from run_as at creation");
1168                         ret = -1;
1169                         goto error_fork;
1170                 }
1171                 global_worker = worker;
1172         }
1173 end:
1174         pthread_mutex_unlock(&worker_lock);
1175         return ret;
1176
1177         /* Error handling. */
1178 error_fork:
1179         for (i = 0; i < 2; i++) {
1180                 if (worker->sockpair[i] < 0) {
1181                         continue;
1182                 }
1183                 if (lttcomm_close_unix_sock(worker->sockpair[i])) {
1184                         PERROR("close");
1185                 }
1186                 worker->sockpair[i] = -1;
1187         }
1188 error_sock:
1189         free(worker);
1190         pthread_mutex_unlock(&worker_lock);
1191         return ret;
1192 }
1193
1194 LTTNG_HIDDEN
1195 void run_as_destroy_worker(void)
1196 {
1197         struct run_as_worker *worker = global_worker;
1198
1199         DBG("Destroying run_as worker");
1200         pthread_mutex_lock(&worker_lock);
1201         if (!worker) {
1202                 goto end;
1203         }
1204         /* Close unix socket */
1205         DBG("Closing run_as worker socket");
1206         if (lttcomm_close_unix_sock(worker->sockpair[0])) {
1207                 PERROR("close");
1208         }
1209         worker->sockpair[0] = -1;
1210         /* Wait for worker. */
1211         for (;;) {
1212                 int status;
1213                 pid_t wait_ret;
1214
1215                 wait_ret = waitpid(worker->pid, &status, 0);
1216                 if (wait_ret < 0) {
1217                         if (errno == EINTR) {
1218                                 continue;
1219                         }
1220                         PERROR("waitpid");
1221                         break;
1222                 }
1223
1224                 if (WIFEXITED(status)) {
1225                         LOG(WEXITSTATUS(status) == 0 ? PRINT_DBG : PRINT_ERR,
1226                                         DEFAULT_RUN_AS_WORKER_NAME " terminated with status code %d",
1227                                         WEXITSTATUS(status));
1228                         break;
1229                 } else if (WIFSIGNALED(status)) {
1230                         ERR(DEFAULT_RUN_AS_WORKER_NAME " was killed by signal %d",
1231                                         WTERMSIG(status));
1232                         break;
1233                 }
1234         }
1235         free(worker);
1236         global_worker = NULL;
1237 end:
1238         pthread_mutex_unlock(&worker_lock);
1239 }