1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2010 The FreeBSD Foundation 5 * Copyright (c) 2010 Pawel Jakub Dawidek <pjd@FreeBSD.org> 6 * All rights reserved. 7 * 8 * This software was developed by Pawel Jakub Dawidek under sponsorship from 9 * the FreeBSD Foundation. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 */ 32 33 #include <sys/types.h> 34 #include <sys/sysctl.h> 35 #include <sys/wait.h> 36 37 #include <errno.h> 38 #include <fcntl.h> 39 #include <paths.h> 40 #include <signal.h> 41 #include <stdbool.h> 42 #include <stdint.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <syslog.h> 47 #include <unistd.h> 48 49 #include <pjdlog.h> 50 51 #include "hooks.h" 52 #include "subr.h" 53 #include "synch.h" 54 55 /* Report processes that are running for too long not often than this value. */ 56 #define REPORT_INTERVAL 60 57 58 /* Are we initialized? */ 59 static bool hooks_initialized = false; 60 61 /* 62 * Keep all processes we forked on a global queue, so we can report nicely 63 * when they finish or report that they are running for a long time. 64 */ 65 #define HOOKPROC_MAGIC_ALLOCATED 0x80090ca 66 #define HOOKPROC_MAGIC_ONLIST 0x80090c0 67 struct hookproc { 68 /* Magic. */ 69 int hp_magic; 70 /* PID of a forked child. */ 71 pid_t hp_pid; 72 /* When process were forked? */ 73 time_t hp_birthtime; 74 /* When we logged previous reported? */ 75 time_t hp_lastreport; 76 /* Path to executable and all the arguments we passed. */ 77 char hp_comm[PATH_MAX]; 78 TAILQ_ENTRY(hookproc) hp_next; 79 }; 80 static TAILQ_HEAD(, hookproc) hookprocs; 81 static pthread_mutex_t hookprocs_lock; 82 83 static void hook_remove(struct hookproc *hp); 84 static void hook_free(struct hookproc *hp); 85 86 static void 87 descriptors(void) 88 { 89 int fd; 90 91 /* 92 * Close all (or almost all) descriptors. 93 */ 94 if (pjdlog_mode_get() == PJDLOG_MODE_STD) { 95 closefrom(MAX(MAX(STDIN_FILENO, STDOUT_FILENO), 96 STDERR_FILENO) + 1); 97 return; 98 } 99 100 closefrom(0); 101 102 /* 103 * Redirect stdin, stdout and stderr to /dev/null. 104 */ 105 fd = open(_PATH_DEVNULL, O_RDONLY); 106 if (fd == -1) { 107 pjdlog_errno(LOG_WARNING, "Unable to open %s for reading", 108 _PATH_DEVNULL); 109 } else if (fd != STDIN_FILENO) { 110 if (dup2(fd, STDIN_FILENO) == -1) { 111 pjdlog_errno(LOG_WARNING, 112 "Unable to duplicate descriptor for stdin"); 113 } 114 close(fd); 115 } 116 fd = open(_PATH_DEVNULL, O_WRONLY); 117 if (fd == -1) { 118 pjdlog_errno(LOG_WARNING, "Unable to open %s for writing", 119 _PATH_DEVNULL); 120 } else { 121 if (fd != STDOUT_FILENO && dup2(fd, STDOUT_FILENO) == -1) { 122 pjdlog_errno(LOG_WARNING, 123 "Unable to duplicate descriptor for stdout"); 124 } 125 if (fd != STDERR_FILENO && dup2(fd, STDERR_FILENO) == -1) { 126 pjdlog_errno(LOG_WARNING, 127 "Unable to duplicate descriptor for stderr"); 128 } 129 if (fd != STDOUT_FILENO && fd != STDERR_FILENO) 130 close(fd); 131 } 132 } 133 134 void 135 hook_init(void) 136 { 137 138 PJDLOG_ASSERT(!hooks_initialized); 139 140 mtx_init(&hookprocs_lock); 141 TAILQ_INIT(&hookprocs); 142 hooks_initialized = true; 143 } 144 145 void 146 hook_fini(void) 147 { 148 struct hookproc *hp; 149 150 PJDLOG_ASSERT(hooks_initialized); 151 152 mtx_lock(&hookprocs_lock); 153 while ((hp = TAILQ_FIRST(&hookprocs)) != NULL) { 154 PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST); 155 PJDLOG_ASSERT(hp->hp_pid > 0); 156 157 hook_remove(hp); 158 hook_free(hp); 159 } 160 mtx_unlock(&hookprocs_lock); 161 162 mtx_destroy(&hookprocs_lock); 163 TAILQ_INIT(&hookprocs); 164 hooks_initialized = false; 165 } 166 167 static struct hookproc * 168 hook_alloc(const char *path, char **args) 169 { 170 struct hookproc *hp; 171 unsigned int ii; 172 173 hp = malloc(sizeof(*hp)); 174 if (hp == NULL) { 175 pjdlog_error("Unable to allocate %zu bytes of memory for a hook.", 176 sizeof(*hp)); 177 return (NULL); 178 } 179 180 hp->hp_pid = 0; 181 hp->hp_birthtime = hp->hp_lastreport = time(NULL); 182 (void)strlcpy(hp->hp_comm, path, sizeof(hp->hp_comm)); 183 /* We start at 2nd argument as we don't want to have exec name twice. */ 184 for (ii = 1; args[ii] != NULL; ii++) { 185 (void)snprlcat(hp->hp_comm, sizeof(hp->hp_comm), " %s", 186 args[ii]); 187 } 188 if (strlen(hp->hp_comm) >= sizeof(hp->hp_comm) - 1) { 189 pjdlog_error("Exec path too long, correct configuration file."); 190 free(hp); 191 return (NULL); 192 } 193 hp->hp_magic = HOOKPROC_MAGIC_ALLOCATED; 194 return (hp); 195 } 196 197 static void 198 hook_add(struct hookproc *hp, pid_t pid) 199 { 200 201 PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED); 202 PJDLOG_ASSERT(hp->hp_pid == 0); 203 204 hp->hp_pid = pid; 205 mtx_lock(&hookprocs_lock); 206 hp->hp_magic = HOOKPROC_MAGIC_ONLIST; 207 TAILQ_INSERT_TAIL(&hookprocs, hp, hp_next); 208 mtx_unlock(&hookprocs_lock); 209 } 210 211 static void 212 hook_remove(struct hookproc *hp) 213 { 214 215 PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST); 216 PJDLOG_ASSERT(hp->hp_pid > 0); 217 PJDLOG_ASSERT(mtx_owned(&hookprocs_lock)); 218 219 TAILQ_REMOVE(&hookprocs, hp, hp_next); 220 hp->hp_magic = HOOKPROC_MAGIC_ALLOCATED; 221 } 222 223 static void 224 hook_free(struct hookproc *hp) 225 { 226 227 PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED); 228 PJDLOG_ASSERT(hp->hp_pid > 0); 229 230 hp->hp_magic = 0; 231 free(hp); 232 } 233 234 static struct hookproc * 235 hook_find(pid_t pid) 236 { 237 struct hookproc *hp; 238 239 PJDLOG_ASSERT(mtx_owned(&hookprocs_lock)); 240 241 TAILQ_FOREACH(hp, &hookprocs, hp_next) { 242 PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST); 243 PJDLOG_ASSERT(hp->hp_pid > 0); 244 245 if (hp->hp_pid == pid) 246 break; 247 } 248 249 return (hp); 250 } 251 252 void 253 hook_check_one(pid_t pid, int status) 254 { 255 struct hookproc *hp; 256 257 mtx_lock(&hookprocs_lock); 258 hp = hook_find(pid); 259 if (hp == NULL) { 260 mtx_unlock(&hookprocs_lock); 261 pjdlog_debug(1, "Unknown process pid=%u", pid); 262 return; 263 } 264 hook_remove(hp); 265 mtx_unlock(&hookprocs_lock); 266 if (WIFEXITED(status) && WEXITSTATUS(status) == 0) { 267 pjdlog_debug(1, "Hook exited gracefully (pid=%u, cmd=[%s]).", 268 pid, hp->hp_comm); 269 } else if (WIFSIGNALED(status)) { 270 pjdlog_error("Hook was killed (pid=%u, signal=%d, cmd=[%s]).", 271 pid, WTERMSIG(status), hp->hp_comm); 272 } else { 273 pjdlog_error("Hook exited ungracefully (pid=%u, exitcode=%d, cmd=[%s]).", 274 pid, WIFEXITED(status) ? WEXITSTATUS(status) : -1, 275 hp->hp_comm); 276 } 277 hook_free(hp); 278 } 279 280 void 281 hook_check(void) 282 { 283 struct hookproc *hp, *hp2; 284 time_t now; 285 286 PJDLOG_ASSERT(hooks_initialized); 287 288 pjdlog_debug(2, "Checking hooks."); 289 290 /* 291 * Report about processes that are running for a long time. 292 */ 293 now = time(NULL); 294 mtx_lock(&hookprocs_lock); 295 TAILQ_FOREACH_SAFE(hp, &hookprocs, hp_next, hp2) { 296 PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST); 297 PJDLOG_ASSERT(hp->hp_pid > 0); 298 299 /* 300 * If process doesn't exists we somehow missed it. 301 * Not much can be done expect for logging this situation. 302 */ 303 if (kill(hp->hp_pid, 0) == -1 && errno == ESRCH) { 304 pjdlog_warning("Hook disappeared (pid=%u, cmd=[%s]).", 305 hp->hp_pid, hp->hp_comm); 306 hook_remove(hp); 307 hook_free(hp); 308 continue; 309 } 310 311 /* 312 * Skip processes younger than 1 minute. 313 */ 314 if (now - hp->hp_lastreport < REPORT_INTERVAL) 315 continue; 316 317 /* 318 * Hook is running for too long, report it. 319 */ 320 pjdlog_warning("Hook is running for %ju seconds (pid=%u, cmd=[%s]).", 321 (uintmax_t)(now - hp->hp_birthtime), hp->hp_pid, 322 hp->hp_comm); 323 hp->hp_lastreport = now; 324 } 325 mtx_unlock(&hookprocs_lock); 326 } 327 328 void 329 hook_exec(const char *path, ...) 330 { 331 va_list ap; 332 333 va_start(ap, path); 334 hook_execv(path, ap); 335 va_end(ap); 336 } 337 338 void 339 hook_execv(const char *path, va_list ap) 340 { 341 struct hookproc *hp; 342 char *args[64]; 343 unsigned int ii; 344 sigset_t mask; 345 pid_t pid; 346 347 PJDLOG_ASSERT(hooks_initialized); 348 349 if (path == NULL || path[0] == '\0') 350 return; 351 352 memset(args, 0, sizeof(args)); 353 args[0] = __DECONST(char *, path); 354 for (ii = 1; ii < sizeof(args) / sizeof(args[0]); ii++) { 355 args[ii] = va_arg(ap, char *); 356 if (args[ii] == NULL) 357 break; 358 } 359 PJDLOG_ASSERT(ii < sizeof(args) / sizeof(args[0])); 360 361 hp = hook_alloc(path, args); 362 if (hp == NULL) 363 return; 364 365 pjdlog_debug(1, "Executing hook: %s", hp->hp_comm); 366 367 pid = fork(); 368 switch (pid) { 369 case -1: /* Error. */ 370 pjdlog_errno(LOG_ERR, "Unable to fork to execute %s", path); 371 hook_free(hp); 372 return; 373 case 0: /* Child. */ 374 descriptors(); 375 PJDLOG_VERIFY(sigemptyset(&mask) == 0); 376 PJDLOG_VERIFY(sigprocmask(SIG_SETMASK, &mask, NULL) == 0); 377 /* 378 * Dummy handler set for SIGCHLD in the parent will be restored 379 * to SIG_IGN on execv(3) below, so there is no need to do 380 * anything with it. 381 */ 382 execv(path, args); 383 pjdlog_errno(LOG_ERR, "Unable to execute %s", path); 384 exit(EX_SOFTWARE); 385 default: /* Parent. */ 386 hook_add(hp, pid); 387 break; 388 } 389 } 390