atrun.tproj/atrun.c

   1 /*
   2  *  atrun.c - run jobs queued by at; run with root privileges.
   3  *  Copyright (C) 1993, 1994 Thomas Koenig
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. The name of the author(s) may not be used to endorse or promote
  11  *    products derived from this software without specific prior written
  12  *    permission.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
  15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  17  * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
  18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  21  * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  24  */
  25
  26 #ifndef lint
  27 static const char rcsid[] =
  28   "$FreeBSD: src/libexec/atrun/atrun.c,v 1.18 2004/07/11 17:37:32 stefanf Exp $";
  29 #endif /* not lint */
  30
  31 /* System Headers */
  32
  33 #include <sys/fcntl.h>
  34 #include <sys/types.h>
  35 #include <sys/stat.h>
  36 #include <sys/wait.h>
  37 #include <sys/param.h>
  38 #include <ctype.h>
  39 #include <dirent.h>
  40 #include <err.h>
  41 #include <grp.h>
  42 #include <pwd.h>
  43 #include <signal.h>
  44 #include <stddef.h>
  45 #include <stdio.h>
  46 #include <stdlib.h>
  47 #include <string.h>
  48 #include <syslog.h>
  49 #include <time.h>
  50 #include <unistd.h>
  51 #include <utmp.h>
  52 #if 1
  53 #include <paths.h>
  54 #else
  55 #include <getopt.h>
  56 #endif
  57
  58 #if (MAXLOGNAME-1) > UT_NAMESIZE
  59 #define LOGNAMESIZE UT_NAMESIZE
  60 #else
  61 #define LOGNAMESIZE (MAXLOGNAME-1)
  62 #endif
  63
  64 /* Local headers */
  65
  66 #define MAIN
  67 #include "privs.h"
  68 #include "pathnames.h"
  69 /* Macros */
  70
  71 #ifndef ATJOB_DIR
  72 #define ATJOB_DIR _PATH_ATJOBS
  73 #endif
  74
  75 #ifndef ATSPOOL_DIR
  76 #define ATSPOOL_DIR _PATH_ATSPOOL
  77 #endif
  78
  79 #ifndef LOADAVG_MX
  80 #define LOADAVG_MX 1.5
  81 #endif
  82
  83 /* File scope variables */
  84
  85 static int debug = 0;
  86
  87 void perr(const char *a);
  88 static void usage(void);
  89
  90 /* Local functions */
  91 static int
  92 write_string(int fd, const char* a)
  93 {
  94     return write(fd, a, strlen(a));
  95 }
  96
  97 #undef DEBUG_FORK
  98 #ifdef DEBUG_FORK
  99 static pid_t
 100 myfork(void)
 101 {
 102         pid_t res;
 103         res = fork();
 104         if (res == 0)
 105             kill(getpid(),SIGSTOP);
 106         return res;
 107 }
 108
 109 #define fork myfork
 110 #endif
 111
 112 static void
 113 run_file(const char *filename, uid_t uid, gid_t gid)
 114 {
 115 /* Run a file by spawning off a process which redirects I/O,
 116  * spawns a subshell, then waits for it to complete and sends
 117  * mail to the user.
 118  */
 119     pid_t pid;
 120     int fd_out, fd_in;
 121     int queue;
 122     char mailbuf[LOGNAMESIZE + 1], fmt[49];
 123     char *mailname = NULL;
 124     FILE *stream;
 125     int send_mail = 0;
 126     struct stat buf, lbuf;
 127     off_t size;
 128     struct passwd *pentry;
 129     int fflags;
 130     long nuid;
 131     long ngid;
 132
 133
 134     PRIV_START
 135
 136     if (chmod(filename, S_IRUSR) != 0)
 137     {
 138         perr("cannot change file permissions");
 139     }
 140
 141     PRIV_END
 142
 143     pid = fork();
 144     if (pid == -1)
 145         perr("cannot fork");
 146
 147     else if (pid != 0)
 148         return;
 149
 150     /* Let's see who we mail to.  Hopefully, we can read it from
 151      * the command file; if not, send it to the owner, or, failing that,
 152      * to root.
 153      */
 154
 155     pentry = getpwuid(uid);
 156     if (pentry == NULL)
 157     {
 158         syslog(LOG_ERR,"Userid %lu not found - aborting job %s",
 159                (unsigned long) uid, filename);
 160         exit(EXIT_FAILURE);
 161     }
 162     PRIV_START
 163
 164     stream=fopen(filename, "r");
 165
 166     PRIV_END
 167
 168 #ifdef __FreeBSD__
 169     if (pentry->pw_expire && time(NULL) >= pentry->pw_expire)
 170     {
 171         syslog(LOG_ERR, "Userid %lu is expired - aborting job %s",
 172                 (unsigned long) uid, filename);
 173         exit(EXIT_FAILURE);
 174     }
 175 #endif
 176
 177     if (stream == NULL)
 178         perr("cannot open input file");
 179
 180     if ((fd_in = dup(fileno(stream))) <0)
 181         perr("error duplicating input file descriptor");
 182
 183     if (fstat(fd_in, &buf) == -1)
 184         perr("error in fstat of input file descriptor");
 185
 186     if (lstat(filename, &lbuf) == -1)
 187         perr("error in fstat of input file");
 188
 189     if (S_ISLNK(lbuf.st_mode)) {
 190         syslog(LOG_ERR,"Symbolic link encountered in job %s - aborting",
 191                 filename);
 192         exit(EXIT_FAILURE);
 193     }
 194     if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) ||
 195         (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) ||
 196         (lbuf.st_size!=buf.st_size)) {
 197         syslog(LOG_ERR,"Somebody changed files from under us for job %s - "
 198         "aborting",filename);
 199         exit(EXIT_FAILURE);
 200     }
 201     if (buf.st_nlink > 1) {
 202         syslog(LOG_ERR,"Someboy is trying to run a linked script for job %s",
 203                 filename);
 204         exit(EXIT_FAILURE);
 205     }
 206     if ((fflags = fcntl(fd_in, F_GETFD)) <0)
 207         perr("error in fcntl");
 208
 209     fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
 210
 211     snprintf(fmt, sizeof(fmt),
 212         "#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d",
 213                           LOGNAMESIZE);
 214     if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4) {
 215         syslog(LOG_ERR,"File %s is in wrong format - aborting", filename);
 216         exit(EXIT_FAILURE);
 217     }
 218     if (mailbuf[0] == '-') {
 219         syslog(LOG_ERR,"illegal mail name %s in %s",mailbuf,filename);
 220         exit(EXIT_FAILURE);
 221     }
 222     mailname = mailbuf;
 223     if (nuid != uid) {
 224         syslog(LOG_ERR,"Job %s - userid %ld does not match file uid %lu",
 225                 filename, nuid, (unsigned long)uid);
 226         exit(EXIT_FAILURE);
 227     }
 228     if (ngid != gid) {
 229         syslog(LOG_ERR,"Job %s - groupid %ld does not match file gid %lu",
 230                 filename, ngid, (unsigned long)gid);
 231         exit(EXIT_FAILURE);
 232     }
 233     fclose(stream);
 234     if (chdir(ATSPOOL_DIR) < 0)
 235         perr("cannot chdir to " ATSPOOL_DIR);
 236
 237     /* Create a file to hold the output of the job we are about to run.
 238      * Write the mail header.
 239      */
 240     if((fd_out=open(filename,
 241                 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0)
 242         perr("cannot create output file");
 243
 244     write_string(fd_out, "Subject: Output from your job ");
 245     write_string(fd_out, filename);
 246     write_string(fd_out, "\n\n");
 247     fstat(fd_out, &buf);
 248     size = buf.st_size;
 249
 250     close(STDIN_FILENO);
 251     close(STDOUT_FILENO);
 252     close(STDERR_FILENO);
 253
 254     pid = fork();
 255     if (pid < 0)
 256         perr("error in fork");
 257
 258     else if (pid == 0)
 259     {
 260         char *nul = NULL;
 261         char **nenvp = &nul;
 262
 263         /* Set up things for the child; we want standard input from the input file,
 264          * and standard output and error sent to our output file.
 265          */
 266
 267         if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0)
 268             perr("error in lseek");
 269
 270         if (dup(fd_in) != STDIN_FILENO)
 271             perr("error in I/O redirection");
 272
 273         if (dup(fd_out) != STDOUT_FILENO)
 274             perr("error in I/O redirection");
 275
 276         if (dup(fd_out) != STDERR_FILENO)
 277             perr("error in I/O redirection");
 278
 279         close(fd_in);
 280         close(fd_out);
 281         if (chdir(ATJOB_DIR) < 0)
 282             perr("cannot chdir to " ATJOB_DIR);
 283
 284         queue = *filename;
 285
 286         PRIV_START
 287
 288         nice(tolower(queue) - 'a');
 289
 290         if (initgroups(pentry->pw_name,pentry->pw_gid))
 291             perr("cannot delete saved userids");
 292
 293         if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
 294             perr("cannot change group");
 295
 296         if (setlogin(pentry->pw_name))
 297             perr("cannot set login name");
 298
 299         if (setuid(uid) < 0 || seteuid(uid) < 0)
 300             perr("cannot set user id");
 301
 302         if (chdir(pentry->pw_dir))
 303                 chdir("/");
 304
 305         if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0)
 306             perr("exec failed for /bin/sh");
 307
 308         PRIV_END
 309     }
 310     /* We're the parent.  Let's wait.
 311      */
 312     close(fd_in);
 313     close(fd_out);
 314     waitpid(pid, (int *) NULL, 0);
 315
 316     /* Send mail.  Unlink the output file first, so it is deleted after
 317      * the run.
 318      */
 319     stat(filename, &buf);
 320     if (open(filename, O_RDONLY) != STDIN_FILENO)
 321         perr("open of jobfile failed");
 322
 323     unlink(filename);
 324     if ((buf.st_size != size) || send_mail)
 325     {
 326         PRIV_START
 327
 328         if (initgroups(pentry->pw_name,pentry->pw_gid))
 329             perr("cannot delete saved userids");
 330
 331         if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
 332             perr("cannot change group");
 333
 334         if (setlogin(pentry->pw_name))
 335             perr("cannot set login name");
 336
 337         if (setuid(uid) < 0 || seteuid(uid) < 0)
 338             perr("cannot set user id");
 339
 340         if (chdir(pentry->pw_dir))
 341                 chdir("/");
 342
 343 #if 1
 344         execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service",
 345                         "-odi", "-oem",
 346                         mailname, (char *) NULL);
 347 #else
 348         execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL);
 349 #endif
 350             perr("exec failed for mail command");
 351
 352         PRIV_END
 353     }
 354     exit(EXIT_SUCCESS);
 355 }
 356
 357 /* Global functions */
 358
 359 /* Needed in gloadavg.c */
 360 void
 361 perr(const char *a)
 362 {
 363     if (debug)
 364     {
 365         warn("%s", a);
 366     }
 367     else
 368         syslog(LOG_ERR, "%s: %m", a);
 369
 370     exit(EXIT_FAILURE);
 371 }
 372
 373 int
 374 main(int argc, char *argv[])
 375 {
 376 /* Browse through  ATJOB_DIR, checking all the jobfiles wether they should
 377  * be executed and or deleted. The queue is coded into the first byte of
 378  * the job filename, the date (in minutes since Eon) as a hex number in the
 379  * following eight bytes, followed by a dot and a serial number.  A file
 380  * which has not been executed yet is denoted by its execute - bit set.
 381  * For those files which are to be executed, run_file() is called, which forks
 382  * off a child which takes care of I/O redirection, forks off another child
 383  * for execution and yet another one, optionally, for sending mail.
 384  * Files which already have run are removed during the next invocation.
 385  */
 386     DIR *spool;
 387     struct dirent *dirent;
 388     struct stat buf;
 389     unsigned long ctm;
 390     unsigned long jobno;
 391     char queue;
 392     time_t now, run_time;
 393     char batch_name[] = "Z2345678901234";
 394     uid_t batch_uid;
 395     gid_t batch_gid;
 396     int c;
 397     int run_batch;
 398     double load_avg = LOADAVG_MX, la;
 399
 400 /* We don't need root privileges all the time; running under uid and gid daemon
 401  * is fine.
 402  */
 403
 404     RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID)
 405
 406     openlog("atrun", LOG_PID, LOG_CRON);
 407
 408     opterr = 0;
 409     while((c=getopt(argc, argv, "dl:"))!= -1)
 410     {
 411         switch (c)
 412         {
 413         case 'l':
 414             if (sscanf(optarg, "%lf", &load_avg) != 1)
 415                 perr("garbled option -l");
 416             if (load_avg <= 0.)
 417                 load_avg = LOADAVG_MX;
 418             break;
 419
 420         case 'd':
 421             debug ++;
 422             break;
 423
 424         case '?':
 425         default:
 426             usage();
 427         }
 428     }
 429
 430     if (chdir(ATJOB_DIR) != 0)
 431         perr("cannot change to " ATJOB_DIR);
 432
 433     /* Main loop. Open spool directory for reading and look over all the
 434      * files in there. If the filename indicates that the job should be run
 435      * and the x bit is set, fork off a child which sets its user and group
 436      * id to that of the files and exec a /bin/sh which executes the shell
 437      * script. Unlink older files if they should no longer be run.  For
 438      * deletion, their r bit has to be turned on.
 439      *
 440      * Also, pick the oldest batch job to run, at most one per invocation of
 441      * atrun.
 442      */
 443     if ((spool = opendir(".")) == NULL)
 444         perr("cannot read " ATJOB_DIR);
 445
 446     now = time(NULL);
 447     run_batch = 0;
 448     batch_uid = (uid_t) -1;
 449     batch_gid = (gid_t) -1;
 450
 451     while ((dirent = readdir(spool)) != NULL) {
 452         if (stat(dirent->d_name,&buf) != 0)
 453             perr("cannot stat in " ATJOB_DIR);
 454
 455         /* We don't want directories
 456          */
 457         if (!S_ISREG(buf.st_mode))
 458             continue;
 459
 460         if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3)
 461             continue;
 462
 463         run_time = (time_t) ctm*60;
 464
 465         if ((S_IXUSR & buf.st_mode) && (run_time <=now)) {
 466             if (isupper(queue) && (strcmp(batch_name,dirent->d_name) > 0)) {
 467                 run_batch = 1;
 468                 strncpy(batch_name, dirent->d_name, sizeof(batch_name));
 469                 batch_uid = buf.st_uid;
 470                 batch_gid = buf.st_gid;
 471             }
 472
 473         /* The file is executable and old enough
 474          */
 475             if (islower(queue))
 476                 run_file(dirent->d_name, buf.st_uid, buf.st_gid);
 477         }
 478         /*  Delete older files
 479          */
 480         if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode))
 481             unlink(dirent->d_name);
 482     }
 483     /* run the single batch file, if any
 484     */
 485     if (run_batch && (getloadavg(&la, 1) == 1) && la < load_avg)
 486         run_file(batch_name, batch_uid, batch_gid);
 487
 488     closelog();
 489     exit(EXIT_SUCCESS);
 490 }
 491
 492 static void
 493 usage(void)
 494 {
 495     if (debug)
 496         fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n");
 497     else
 498         syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]");
 499
 500     exit(EXIT_FAILURE);
 501 }