sbin/hastd/hooks.c

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