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 #include <sys/cdefs.h>
  27 #ifndef lint
  28 __FBSDID("$FreeBSD: src/libexec/atrun/atrun.c,v 1.27 2009/12/25 10:30:54 ed 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 <stdarg.h>
  45 #include <stddef.h>
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include <string.h>
  49 #include <syslog.h>
  50 #include <time.h>
  51 #include <unistd.h>
  52 #if 1
  53 #include <paths.h>
  54 #else
  55 #include <getopt.h>
  56 #endif
  57 #ifdef LOGIN_CAP
  58 #include <login_cap.h>
  59 #endif
  60 #ifdef PAM
  61 #include <security/pam_appl.h>
  62 #include <security/openpam.h>
  63 #endif
  64
  65 /* Local headers */
  66
  67 #define MAIN
  68 #include "privs.h"
  69 #include "pathnames.h"
  70
  71 /* Macros */
  72
  73 #ifndef ATJOB_DIR
  74 #define ATJOB_DIR _PATH_ATJOBS
  75 #endif
  76
  77 #ifndef ATSPOOL_DIR
  78 #define ATSPOOL_DIR _PATH_ATSPOOL
  79 #endif
  80
  81 #ifndef LOADAVG_MX
  82 #define LOADAVG_MX 1.5
  83 #endif
  84
  85 /* File scope variables */
  86
  87 static const char * const atrun = "atrun"; /* service name for syslog etc. */
  88 static int debug = 0;
  89
  90 void perr(const char *fmt, ...);
  91 void perrx(const char *fmt, ...);
  92 static void usage(void);
  93
  94 /* Local functions */
  95 static ssize_t
  96 write_string(int fd, const char* a)
  97 {
  98     return write(fd, a, strlen(a));
  99 }
 100
 101 #undef DEBUG_FORK
 102 #ifdef DEBUG_FORK
 103 static pid_t
 104 myfork(void)
 105 {
 106         pid_t res;
 107         res = fork();
 108         if (res == 0)
 109             kill(getpid(),SIGSTOP);
 110         return res;
 111 }
 112
 113 #define fork myfork
 114 #endif
 115
 116 static void
 117 run_file(const char *filename, uid_t uid, gid_t gid)
 118 {
 119 /* Run a file by spawning off a process which redirects I/O,
 120  * spawns a subshell, then waits for it to complete and sends
 121  * mail to the user.
 122  */
 123     pid_t pid;
 124     int fd_out, fd_in;
 125     int queue;
 126     char mailbuf[MAXLOGNAME], fmt[64];
 127     char *mailname = NULL;
 128     FILE *stream;
 129     int send_mail = 0;
 130     struct stat buf, lbuf;
 131     off_t size;
 132     struct passwd *pentry;
 133     int fflags;
 134     long nuid;
 135     long ngid;
 136 #ifdef PAM
 137     pam_handle_t *pamh = NULL;
 138     int pam_err;
 139     struct pam_conv pamc = {
 140         .conv = openpam_nullconv,
 141         .appdata_ptr = NULL
 142     };
 143 #endif
 144
 145     PRIV_START
 146
 147     if (chmod(filename, S_IRUSR) != 0)
 148     {
 149         perr("cannot change file permissions");
 150     }
 151
 152     PRIV_END
 153
 154     pid = fork();
 155     if (pid == -1)
 156         perr("cannot fork");
 157
 158     else if (pid != 0)
 159         return;
 160
 161 #ifdef __APPLE__
 162     {
 163         pid_t pg = setsid();
 164         if (pg == -1) syslog(LOG_ERR,"setsid() failed: %m");
 165     }
 166 #endif
 167
 168     /* Let's see who we mail to.  Hopefully, we can read it from
 169      * the command file; if not, send it to the owner, or, failing that,
 170      * to root.
 171      */
 172
 173     pentry = getpwuid(uid);
 174     if (pentry == NULL)
 175         perrx("Userid %lu not found - aborting job %s",
 176                 (unsigned long) uid, filename);
 177
 178 #ifdef PAM
 179     PRIV_START
 180
 181     pam_err = pam_start(atrun, pentry->pw_name, &pamc, &pamh);
 182     if (pam_err != PAM_SUCCESS)
 183         perrx("cannot start PAM: %s", pam_strerror(pamh, pam_err));
 184
 185     pam_err = pam_acct_mgmt(pamh, PAM_SILENT);
 186     /* Expired password shouldn't prevent the job from running. */
 187     if (pam_err != PAM_SUCCESS && pam_err != PAM_NEW_AUTHTOK_REQD)
 188         perrx("Account %s (userid %lu) unavailable for job %s: %s",
 189             pentry->pw_name, (unsigned long)uid,
 190             filename, pam_strerror(pamh, pam_err));
 191
 192     pam_end(pamh, pam_err);
 193
 194     PRIV_END
 195 #endif /* PAM */
 196
 197     PRIV_START
 198
 199     stream=fopen(filename, "r");
 200
 201     PRIV_END
 202
 203     if (stream == NULL)
 204         perr("cannot open input file");
 205
 206     if ((fd_in = dup(fileno(stream))) <0)
 207         perr("error duplicating input file descriptor");
 208
 209     if (fstat(fd_in, &buf) == -1)
 210         perr("error in fstat of input file descriptor");
 211
 212     if (lstat(filename, &lbuf) == -1)
 213         perr("error in fstat of input file");
 214
 215     if (S_ISLNK(lbuf.st_mode))
 216         perrx("Symbolic link encountered in job %s - aborting", filename);
 217
 218     if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) ||
 219         (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) ||
 220         (lbuf.st_size!=buf.st_size))
 221         perrx("Somebody changed files from under us for job %s - aborting",
 222                 filename);
 223
 224     if (buf.st_nlink > 1)
 225         perrx("Somebody is trying to run a linked script for job %s", filename);
 226
 227     if ((fflags = fcntl(fd_in, F_GETFD)) <0)
 228         perr("error in fcntl");
 229
 230     fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
 231
 232     snprintf(fmt, sizeof(fmt),
 233         "#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d",
 234                           MAXLOGNAME - 1);
 235
 236     if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4)
 237         perrx("File %s is in wrong format - aborting", filename);
 238
 239     if (mailbuf[0] == '-')
 240         perrx("Illegal mail name %s in %s", mailbuf, filename);
 241
 242     mailname = mailbuf;
 243
 244     if (nuid != uid)
 245         perrx("Job %s - userid %ld does not match file uid %lu",
 246                 filename, nuid, (unsigned long)uid);
 247
 248     if (ngid != gid)
 249         perrx("Job %s - groupid %ld does not match file gid %lu",
 250                 filename, ngid, (unsigned long)gid);
 251
 252     fclose(stream);
 253
 254     if (chdir(ATSPOOL_DIR) < 0)
 255         perr("cannot chdir to %s", ATSPOOL_DIR);
 256
 257     /* Create a file to hold the output of the job we are about to run.
 258      * Write the mail header.
 259      */
 260     if((fd_out=open(filename,
 261                 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0)
 262         perr("cannot create output file");
 263
 264     write_string(fd_out, "Subject: Output from your job ");
 265     write_string(fd_out, filename);
 266     write_string(fd_out, "\n\n");
 267     fstat(fd_out, &buf);
 268     size = buf.st_size;
 269
 270     close(STDIN_FILENO);
 271     close(STDOUT_FILENO);
 272     close(STDERR_FILENO);
 273
 274     pid = fork();
 275     if (pid < 0)
 276         perr("error in fork");
 277
 278     else if (pid == 0)
 279     {
 280         char *nul = NULL;
 281         char **nenvp = &nul;
 282
 283         /* Set up things for the child; we want standard input from the input file,
 284          * and standard output and error sent to our output file.
 285          */
 286
 287         if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0)
 288             perr("error in lseek");
 289
 290         if (dup(fd_in) != STDIN_FILENO)
 291             perr("error in I/O redirection");
 292
 293         if (dup(fd_out) != STDOUT_FILENO)
 294             perr("error in I/O redirection");
 295
 296         if (dup(fd_out) != STDERR_FILENO)
 297             perr("error in I/O redirection");
 298
 299         close(fd_in);
 300         close(fd_out);
 301         if (chdir(ATJOB_DIR) < 0)
 302             perr("cannot chdir to %s", ATJOB_DIR);
 303
 304         queue = *filename;
 305
 306         PRIV_START
 307
 308         nice(tolower(queue) - 'a');
 309
 310 #ifdef LOGIN_CAP
 311         /*
 312          * For simplicity and safety, set all aspects of the user context
 313          * except for a selected subset:  Don't set priority, which was
 314          * set based on the queue file name according to the tradition.
 315          * Don't bother to set environment, including path vars, either
 316          * because it will be discarded anyway.  Although the job file
 317          * should set umask, preset it here just in case.
 318          */
 319         if (setusercontext(NULL, pentry, uid, LOGIN_SETALL &
 320                 ~(LOGIN_SETPRIORITY | LOGIN_SETPATH | LOGIN_SETENV)) != 0)
 321             exit(EXIT_FAILURE); /* setusercontext() logged the error */
 322 #else /* LOGIN_CAP */
 323         if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
 324             perr("cannot change group");
 325
 326         if (initgroups(pentry->pw_name,pentry->pw_gid))
 327             perr("cannot init group access list");
 328
 329         if (setlogin(pentry->pw_name))
 330             perr("cannot set login name");
 331
 332         if (setuid(uid) < 0 || seteuid(uid) < 0)
 333             perr("cannot set user id");
 334 #endif /* LOGIN_CAP */
 335
 336         if (chdir(pentry->pw_dir))
 337                 chdir("/");
 338
 339         if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0)
 340             perr("exec failed for /bin/sh");
 341
 342         PRIV_END
 343     }
 344     /* We're the parent.  Let's wait.
 345      */
 346     close(fd_in);
 347     close(fd_out);
 348     waitpid(pid, (int *) NULL, 0);
 349
 350     /* Send mail.  Unlink the output file first, so it is deleted after
 351      * the run.
 352      */
 353     stat(filename, &buf);
 354     if (open(filename, O_RDONLY) != STDIN_FILENO)
 355         perr("open of jobfile failed");
 356
 357     unlink(filename);
 358     if ((buf.st_size != size) || send_mail)
 359     {
 360         PRIV_START
 361
 362 #ifdef LOGIN_CAP
 363         /*
 364          * This time set full context to run the mailer.
 365          */
 366         if (setusercontext(NULL, pentry, uid, LOGIN_SETALL) != 0)
 367             exit(EXIT_FAILURE); /* setusercontext() logged the error */
 368 #else /* LOGIN_CAP */
 369         if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
 370             perr("cannot change group");
 371
 372         if (initgroups(pentry->pw_name,pentry->pw_gid))
 373             perr("cannot init group access list");
 374
 375         if (setlogin(pentry->pw_name))
 376             perr("cannot set login name");
 377
 378         if (setuid(uid) < 0 || seteuid(uid) < 0)
 379             perr("cannot set user id");
 380 #endif /* LOGIN_CAP */
 381
 382         if (chdir(pentry->pw_dir))
 383                 chdir("/");
 384
 385 #if 1
 386         execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service",
 387                         "-odi", "-oem",
 388                         mailname, (char *) NULL);
 389 #else
 390         execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL);
 391 #endif
 392             perr("exec failed for mail command");
 393
 394         PRIV_END
 395     }
 396     exit(EXIT_SUCCESS);
 397 }
 398
 399 /* Global functions */
 400
 401 /* Needed in gloadavg.c */
 402 void
 403 perr(const char *fmt, ...)
 404 {
 405     const char * const fmtadd = ": %m";
 406     char nfmt[strlen(fmt) + strlen(fmtadd) + 1];
 407     va_list ap;
 408
 409     va_start(ap, fmt);
 410     if (debug)
 411     {
 412         vwarn(fmt, ap);
 413     }
 414     else
 415     {
 416         snprintf(nfmt, sizeof(nfmt), "%s%s", fmt, fmtadd);
 417         vsyslog(LOG_ERR, nfmt, ap);
 418     }
 419     va_end(ap);
 420
 421     exit(EXIT_FAILURE);
 422 }
 423
 424 void
 425 perrx(const char *fmt, ...)
 426 {
 427     va_list ap;
 428
 429     va_start(ap, fmt);
 430     if (debug)
 431         vwarnx(fmt, ap);
 432     else
 433         vsyslog(LOG_ERR, fmt, ap);
 434     va_end(ap);
 435
 436     exit(EXIT_FAILURE);
 437 }
 438
 439 int
 440 main(int argc, char *argv[])
 441 {
 442 /* Browse through  ATJOB_DIR, checking all the jobfiles wether they should
 443  * be executed and or deleted. The queue is coded into the first byte of
 444  * the job filename, the date (in minutes since Eon) as a hex number in the
 445  * following eight bytes, followed by a dot and a serial number.  A file
 446  * which has not been executed yet is denoted by its execute - bit set.
 447  * For those files which are to be executed, run_file() is called, which forks
 448  * off a child which takes care of I/O redirection, forks off another child
 449  * for execution and yet another one, optionally, for sending mail.
 450  * Files which already have run are removed during the next invocation.
 451  */
 452     DIR *spool;
 453     struct dirent *dirent;
 454     struct stat buf;
 455     unsigned long ctm;
 456     unsigned long jobno;
 457     char queue;
 458     time_t now, run_time;
 459     char batch_name[] = "Z2345678901234";
 460     uid_t batch_uid;
 461     gid_t batch_gid;
 462     int c;
 463     int run_batch;
 464     double load_avg = LOADAVG_MX, la;
 465
 466 /* We don't need root privileges all the time; running under uid and gid daemon
 467  * is fine.
 468  */
 469
 470     RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID)
 471
 472     openlog(atrun, LOG_PID, LOG_CRON);
 473
 474     opterr = 0;
 475     while((c=getopt(argc, argv, "dl:"))!= -1)
 476     {
 477         switch (c)
 478         {
 479         case 'l':
 480             if (sscanf(optarg, "%lf", &load_avg) != 1)
 481                 perr("garbled option -l");
 482             if (load_avg <= 0.)
 483                 load_avg = LOADAVG_MX;
 484             break;
 485
 486         case 'd':
 487             debug ++;
 488             break;
 489
 490         case '?':
 491         default:
 492             usage();
 493         }
 494     }
 495
 496     if (chdir(ATJOB_DIR) != 0)
 497         perr("cannot change to %s", ATJOB_DIR);
 498
 499     /* Main loop. Open spool directory for reading and look over all the
 500      * files in there. If the filename indicates that the job should be run
 501      * and the x bit is set, fork off a child which sets its user and group
 502      * id to that of the files and exec a /bin/sh which executes the shell
 503      * script. Unlink older files if they should no longer be run.  For
 504      * deletion, their r bit has to be turned on.
 505      *
 506      * Also, pick the oldest batch job to run, at most one per invocation of
 507      * atrun.
 508      */
 509     if ((spool = opendir(".")) == NULL)
 510         perr("cannot read %s", ATJOB_DIR);
 511
 512     now = time(NULL);
 513     run_batch = 0;
 514     batch_uid = (uid_t) -1;
 515     batch_gid = (gid_t) -1;
 516
 517     while ((dirent = readdir(spool)) != NULL) {
 518         if (stat(dirent->d_name,&buf) != 0)
 519             perr("cannot stat in %s", ATJOB_DIR);
 520
 521         /* We don't want directories
 522          */
 523         if (!S_ISREG(buf.st_mode))
 524             continue;
 525
 526         if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3)
 527             continue;
 528
 529         run_time = (time_t) ctm*60;
 530
 531         if ((S_IXUSR & buf.st_mode) && (run_time <=now)) {
 532             if ((isupper(queue) || queue == 'b') && (strcmp(batch_name,dirent->d_name) > 0)) {
 533                 run_batch = 1;
 534                 strlcpy(batch_name, dirent->d_name, sizeof(batch_name));
 535                 batch_uid = buf.st_uid;
 536                 batch_gid = buf.st_gid;
 537             }
 538
 539         /* The file is executable and old enough
 540          */
 541             if (islower(queue))
 542                 run_file(dirent->d_name, buf.st_uid, buf.st_gid);
 543         }
 544         /*  Delete older files
 545          */
 546         if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode))
 547             unlink(dirent->d_name);
 548     }
 549     /* run the single batch file, if any
 550     */
 551     if (run_batch && (getloadavg(&la, 1) == 1) && la < load_avg)
 552         run_file(batch_name, batch_uid, batch_gid);
 553
 554     closelog();
 555 #if __APPLE__
 556     // allow enough time for child processes to call setsid(2)
 557     sleep(1);
 558 #endif
 559     exit(EXIT_SUCCESS);
 560 }
 561
 562 static void
 563 usage(void)
 564 {
 565     if (debug)
 566         fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n");
 567     else
 568         syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]");
 569
 570     exit(EXIT_FAILURE);
 571 }