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