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 <utmpx.h>
  52 #if 1
  53 #include <paths.h>
  54 #else
  55 #include <getopt.h>
  56 #endif
  57
  58 #if (MAXLOGNAME-1) > _UTX_USERSIZE
  59 #define LOGNAMESIZE _UTX_USERSIZE
  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];
 123     char *fmt = NULL;
 124     char *mailname = NULL;
 125     FILE *stream;
 126     int send_mail = 0;
 127     struct stat buf, lbuf;
 128     off_t size;
 129     struct passwd *pentry;
 130     int fflags;
 131     long nuid;
 132     long ngid;
 133
 134
 135     PRIV_START
 136
 137     if (chmod(filename, S_IRUSR) != 0)
 138     {
 139         perr("cannot change file permissions");
 140     }
 141
 142     PRIV_END
 143
 144     pid = fork();
 145     if (pid == -1)
 146         perr("cannot fork");
 147
 148     else if (pid != 0)
 149         return;
 150
 151 #ifdef __APPLE__
 152     {
 153         pid_t pg = setsid();
 154         if (pg == -1) syslog(LOG_ERR,"setsid() failed: %m");
 155     }
 156 #endif
 157
 158     /* Let's see who we mail to.  Hopefully, we can read it from
 159      * the command file; if not, send it to the owner, or, failing that,
 160      * to root.
 161      */
 162
 163     pentry = getpwuid(uid);
 164     if (pentry == NULL)
 165     {
 166         syslog(LOG_ERR,"Userid %lu not found - aborting job %s",
 167                (unsigned long) uid, filename);
 168         exit(EXIT_FAILURE);
 169     }
 170     PRIV_START
 171
 172     stream=fopen(filename, "r");
 173
 174     PRIV_END
 175
 176 #ifdef __FreeBSD__
 177     if (pentry->pw_expire && time(NULL) >= pentry->pw_expire)
 178     {
 179         syslog(LOG_ERR, "Userid %lu is expired - aborting job %s",
 180                 (unsigned long) uid, filename);
 181         exit(EXIT_FAILURE);
 182     }
 183 #endif
 184
 185     if (stream == NULL)
 186         perr("cannot open input file");
 187
 188     if ((fd_in = dup(fileno(stream))) <0)
 189         perr("error duplicating input file descriptor");
 190
 191     if (fstat(fd_in, &buf) == -1)
 192         perr("error in fstat of input file descriptor");
 193
 194     if (lstat(filename, &lbuf) == -1)
 195         perr("error in fstat of input file");
 196
 197     if (S_ISLNK(lbuf.st_mode)) {
 198         syslog(LOG_ERR,"Symbolic link encountered in job %s - aborting",
 199                 filename);
 200         exit(EXIT_FAILURE);
 201     }
 202     if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) ||
 203         (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) ||
 204         (lbuf.st_size!=buf.st_size)) {
 205         syslog(LOG_ERR,"Somebody changed files from under us for job %s - "
 206         "aborting",filename);
 207         exit(EXIT_FAILURE);
 208     }
 209     if (buf.st_nlink > 1) {
 210         syslog(LOG_ERR,"Someboy is trying to run a linked script for job %s",
 211                 filename);
 212         exit(EXIT_FAILURE);
 213     }
 214     if ((fflags = fcntl(fd_in, F_GETFD)) <0)
 215         perr("error in fcntl");
 216
 217     fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
 218
 219     asprintf(&fmt, "%s%d%s",
 220              "#!/bin/sh\n# atrun uid=%ld gid=%ld\n# mail %",
 221              LOGNAMESIZE,
 222              "s %d");
 223     if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4) {
 224         syslog(LOG_ERR,"File %s is in wrong format - aborting", filename);
 225         exit(EXIT_FAILURE);
 226     }
 227     free(fmt);
 228     if (mailbuf[0] == '-') {
 229         syslog(LOG_ERR,"illegal mail name %s in %s",mailbuf,filename);
 230         exit(EXIT_FAILURE);
 231     }
 232     mailname = mailbuf;
 233     if (nuid != uid) {
 234         syslog(LOG_ERR,"Job %s - userid %ld does not match file uid %lu",
 235                 filename, nuid, (unsigned long)uid);
 236         exit(EXIT_FAILURE);
 237     }
 238     if (ngid != gid) {
 239         syslog(LOG_ERR,"Job %s - groupid %ld does not match file gid %lu",
 240                 filename, ngid, (unsigned long)gid);
 241         exit(EXIT_FAILURE);
 242     }
 243     fclose(stream);
 244     if (chdir(ATSPOOL_DIR) < 0)
 245         perr("cannot chdir to " ATSPOOL_DIR);
 246
 247     /* Create a file to hold the output of the job we are about to run.
 248      * Write the mail header.
 249      */
 250     if((fd_out=open(filename,
 251                 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0)
 252         perr("cannot create output file");
 253
 254     write_string(fd_out, "Subject: Output from your job ");
 255     write_string(fd_out, filename);
 256     write_string(fd_out, "\n\n");
 257     fstat(fd_out, &buf);
 258     size = buf.st_size;
 259
 260     close(STDIN_FILENO);
 261     close(STDOUT_FILENO);
 262     close(STDERR_FILENO);
 263
 264     pid = fork();
 265     if (pid < 0)
 266         perr("error in fork");
 267
 268     else if (pid == 0)
 269     {
 270         char *nul = NULL;
 271         char **nenvp = &nul;
 272
 273         /* Set up things for the child; we want standard input from the input file,
 274          * and standard output and error sent to our output file.
 275          */
 276
 277         if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0)
 278             perr("error in lseek");
 279
 280         if (dup(fd_in) != STDIN_FILENO)
 281             perr("error in I/O redirection");
 282
 283         if (dup(fd_out) != STDOUT_FILENO)
 284             perr("error in I/O redirection");
 285
 286         if (dup(fd_out) != STDERR_FILENO)
 287             perr("error in I/O redirection");
 288
 289         close(fd_in);
 290         close(fd_out);
 291         if (chdir(ATJOB_DIR) < 0)
 292             perr("cannot chdir to " ATJOB_DIR);
 293
 294         queue = *filename;
 295
 296         PRIV_START
 297
 298         nice(tolower(queue) - 'a');
 299
 300         if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
 301             perr("cannot change group");
 302
 303         if (initgroups(pentry->pw_name,pentry->pw_gid))
 304             perr("cannot delete saved userids");
 305
 306         if (setlogin(pentry->pw_name))
 307             perr("cannot set login name");
 308
 309         if (setuid(uid) < 0 || seteuid(uid) < 0)
 310             perr("cannot set user id");
 311
 312         if (chdir(pentry->pw_dir))
 313                 chdir("/");
 314
 315         if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0)
 316             perr("exec failed for /bin/sh");
 317
 318         PRIV_END
 319     }
 320     /* We're the parent.  Let's wait.
 321      */
 322     close(fd_in);
 323     close(fd_out);
 324     waitpid(pid, (int *) NULL, 0);
 325
 326     /* Send mail.  Unlink the output file first, so it is deleted after
 327      * the run.
 328      */
 329     stat(filename, &buf);
 330     if (open(filename, O_RDONLY) != STDIN_FILENO)
 331         perr("open of jobfile failed");
 332
 333     unlink(filename);
 334     if ((buf.st_size != size) || send_mail)
 335     {
 336         PRIV_START
 337
 338         if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
 339             perr("cannot change group");
 340
 341         if (initgroups(pentry->pw_name,pentry->pw_gid))
 342             perr("cannot delete saved userids");
 343
 344         if (setlogin(pentry->pw_name))
 345             perr("cannot set login name");
 346
 347         if (setuid(uid) < 0 || seteuid(uid) < 0)
 348             perr("cannot set user id");
 349
 350         if (chdir(pentry->pw_dir))
 351                 chdir("/");
 352
 353 #if 1
 354         execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service",
 355                         "-odi", "-oem",
 356                         mailname, (char *) NULL);
 357 #else
 358         execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL);
 359 #endif
 360             perr("exec failed for mail command");
 361
 362         PRIV_END
 363     }
 364     exit(EXIT_SUCCESS);
 365 }
 366
 367 /* Global functions */
 368
 369 /* Needed in gloadavg.c */
 370 void
 371 perr(const char *a)
 372 {
 373     if (debug)
 374     {
 375         warn("%s", a);
 376     }
 377     else
 378         syslog(LOG_ERR, "%s: %m", a);
 379
 380     exit(EXIT_FAILURE);
 381 }
 382
 383 int
 384 main(int argc, char *argv[])
 385 {
 386 /* Browse through  ATJOB_DIR, checking all the jobfiles wether they should
 387  * be executed and or deleted. The queue is coded into the first byte of
 388  * the job filename, the date (in minutes since Eon) as a hex number in the
 389  * following eight bytes, followed by a dot and a serial number.  A file
 390  * which has not been executed yet is denoted by its execute - bit set.
 391  * For those files which are to be executed, run_file() is called, which forks
 392  * off a child which takes care of I/O redirection, forks off another child
 393  * for execution and yet another one, optionally, for sending mail.
 394  * Files which already have run are removed during the next invocation.
 395  */
 396     DIR *spool;
 397     struct dirent *dirent;
 398     struct stat buf;
 399     unsigned long ctm;
 400     unsigned long jobno;
 401     char queue;
 402     time_t now, run_time;
 403     char batch_name[] = "Z2345678901234";
 404     uid_t batch_uid;
 405     gid_t batch_gid;
 406     int c;
 407     int run_batch;
 408     double load_avg = LOADAVG_MX, la;
 409
 410 /* We don't need root privileges all the time; running under uid and gid daemon
 411  * is fine.
 412  */
 413
 414     RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID)
 415
 416     openlog("atrun", LOG_PID, LOG_CRON);
 417
 418     opterr = 0;
 419     while((c=getopt(argc, argv, "dl:"))!= -1)
 420     {
 421         switch (c)
 422         {
 423         case 'l':
 424             if (sscanf(optarg, "%lf", &load_avg) != 1)
 425                 perr("garbled option -l");
 426             if (load_avg <= 0.)
 427                 load_avg = LOADAVG_MX;
 428             break;
 429
 430         case 'd':
 431             debug ++;
 432             break;
 433
 434         case '?':
 435         default:
 436             usage();
 437         }
 438     }
 439
 440     if (chdir(ATJOB_DIR) != 0)
 441         perr("cannot change to " ATJOB_DIR);
 442
 443     /* Main loop. Open spool directory for reading and look over all the
 444      * files in there. If the filename indicates that the job should be run
 445      * and the x bit is set, fork off a child which sets its user and group
 446      * id to that of the files and exec a /bin/sh which executes the shell
 447      * script. Unlink older files if they should no longer be run.  For
 448      * deletion, their r bit has to be turned on.
 449      *
 450      * Also, pick the oldest batch job to run, at most one per invocation of
 451      * atrun.
 452      */
 453     if ((spool = opendir(".")) == NULL)
 454         perr("cannot read " ATJOB_DIR);
 455
 456     now = time(NULL);
 457     run_batch = 0;
 458     batch_uid = (uid_t) -1;
 459     batch_gid = (gid_t) -1;
 460
 461     while ((dirent = readdir(spool)) != NULL) {
 462         if (stat(dirent->d_name,&buf) != 0)
 463             perr("cannot stat in " ATJOB_DIR);
 464
 465         /* We don't want directories
 466          */
 467         if (!S_ISREG(buf.st_mode))
 468             continue;
 469
 470         if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3)
 471             continue;
 472
 473         run_time = (time_t) ctm*60;
 474
 475         if ((S_IXUSR & buf.st_mode) && (run_time <=now)) {
 476             if (isupper(queue) && (strcmp(batch_name,dirent->d_name) > 0)) {
 477                 run_batch = 1;
 478                 strncpy(batch_name, dirent->d_name, sizeof(batch_name));
 479                 batch_uid = buf.st_uid;
 480                 batch_gid = buf.st_gid;
 481             }
 482
 483         /* The file is executable and old enough
 484          */
 485             if (islower(queue))
 486                 run_file(dirent->d_name, buf.st_uid, buf.st_gid);
 487         }
 488         /*  Delete older files
 489          */
 490         if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode))
 491             unlink(dirent->d_name);
 492     }
 493     /* run the single batch file, if any
 494     */
 495     if (run_batch && (getloadavg(&la, 1) == 1) && la < load_avg)
 496         run_file(batch_name, batch_uid, batch_gid);
 497
 498     closelog();
 499 #if __APPLE__
 500     // allow enough time for child processes to call setsid(2)
 501     sleep(1);
 502 #endif
 503     exit(EXIT_SUCCESS);
 504 }
 505
 506 static void
 507 usage(void)
 508 {
 509     if (debug)
 510         fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n");
 511     else
 512         syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]");
 513
 514     exit(EXIT_FAILURE);
 515 }