system_cmds/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 #include <libiosexec.h>
  66
  67 /* Local headers */
  68
  69 #define MAIN
  70 #include "privs.h"
  71 #include "pathnames.h"
  72
  73 /* Macros */
  74
  75 #ifndef ATJOB_DIR
  76 #define ATJOB_DIR _PATH_ATJOBS
  77 #endif
  78
  79 #ifndef ATSPOOL_DIR
  80 #define ATSPOOL_DIR _PATH_ATSPOOL
  81 #endif
  82
  83 #ifndef LOADAVG_MX
  84 #define LOADAVG_MX 1.5
  85 #endif
  86
  87 /* File scope variables */
  88
  89 static const char * const atrun = "atrun"; /* service name for syslog etc. */
  90 static int debug = 0;
  91
  92 void perr(const char *fmt, ...);
  93 void perrx(const char *fmt, ...);
  94 static void usage(void);
  95
  96 /* Local functions */
  97 static ssize_t
  98 write_string(int fd, const char* a)
  99 {
 100     return write(fd, a, strlen(a));
 101 }
 102
 103 #undef DEBUG_FORK
 104 #ifdef DEBUG_FORK
 105 static pid_t
 106 myfork(void)
 107 {
 108         pid_t res;
 109         res = fork();
 110         if (res == 0)
 111             kill(getpid(),SIGSTOP);
 112         return res;
 113 }
 114
 115 #define fork myfork
 116 #endif
 117
 118 static void
 119 run_file(const char *filename, uid_t uid, gid_t gid)
 120 {
 121 /* Run a file by spawning off a process which redirects I/O,
 122  * spawns a subshell, then waits for it to complete and sends
 123  * mail to the user.
 124  */
 125     pid_t pid;
 126     int fd_out, fd_in;
 127     int queue;
 128     char mailbuf[MAXLOGNAME], fmt[64];
 129     char *mailname = NULL;
 130     FILE *stream;
 131     int send_mail = 0;
 132     struct stat buf, lbuf;
 133     off_t size;
 134     struct passwd *pentry;
 135     int fflags;
 136     long nuid;
 137     long ngid;
 138 #ifdef PAM
 139     pam_handle_t *pamh = NULL;
 140     int pam_err;
 141     struct pam_conv pamc = {
 142         .conv = openpam_nullconv,
 143         .appdata_ptr = NULL
 144     };
 145 #endif
 146
 147     PRIV_START
 148
 149     if (chmod(filename, S_IRUSR) != 0)
 150     {
 151         perr("cannot change file permissions");
 152     }
 153
 154     PRIV_END
 155
 156     pid = fork();
 157     if (pid == -1)
 158         perr("cannot fork");
 159
 160     else if (pid != 0)
 161         return;
 162
 163 #ifdef __APPLE__
 164     {
 165         pid_t pg = setsid();
 166         if (pg == -1) syslog(LOG_ERR,"setsid() failed: %m");
 167     }
 168 #endif
 169
 170     /* Let's see who we mail to.  Hopefully, we can read it from
 171      * the command file; if not, send it to the owner, or, failing that,
 172      * to root.
 173      */
 174
 175     pentry = getpwuid(uid);
 176     if (pentry == NULL)
 177         perrx("Userid %lu not found - aborting job %s",
 178                 (unsigned long) uid, filename);
 179
 180 #ifdef PAM
 181     PRIV_START
 182
 183     pam_err = pam_start(atrun, pentry->pw_name, &pamc, &pamh);
 184     if (pam_err != PAM_SUCCESS)
 185         perrx("cannot start PAM: %s", pam_strerror(pamh, pam_err));
 186
 187     pam_err = pam_acct_mgmt(pamh, PAM_SILENT);
 188     /* Expired password shouldn't prevent the job from running. */
 189     if (pam_err != PAM_SUCCESS && pam_err != PAM_NEW_AUTHTOK_REQD)
 190         perrx("Account %s (userid %lu) unavailable for job %s: %s",
 191             pentry->pw_name, (unsigned long)uid,
 192             filename, pam_strerror(pamh, pam_err));
 193
 194     pam_end(pamh, pam_err);
 195
 196     PRIV_END
 197 #endif /* PAM */
 198
 199     PRIV_START
 200
 201     stream=fopen(filename, "r");
 202
 203     PRIV_END
 204
 205     if (stream == NULL)
 206         perr("cannot open input file");
 207
 208     if ((fd_in = dup(fileno(stream))) <0)
 209         perr("error duplicating input file descriptor");
 210
 211     if (fstat(fd_in, &buf) == -1)
 212         perr("error in fstat of input file descriptor");
 213
 214     if (lstat(filename, &lbuf) == -1)
 215         perr("error in fstat of input file");
 216
 217     if (S_ISLNK(lbuf.st_mode))
 218         perrx("Symbolic link encountered in job %s - aborting", filename);
 219
 220     if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) ||
 221         (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) ||
 222         (lbuf.st_size!=buf.st_size))
 223         perrx("Somebody changed files from under us for job %s - aborting",
 224                 filename);
 225
 226     if (buf.st_nlink > 1)
 227         perrx("Somebody is trying to run a linked script for job %s", filename);
 228
 229     if ((fflags = fcntl(fd_in, F_GETFD)) <0)
 230         perr("error in fcntl");
 231
 232     fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
 233
 234     snprintf(fmt, sizeof(fmt),
 235         "#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d",
 236                           MAXLOGNAME - 1);
 237
 238     if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4)
 239         perrx("File %s is in wrong format - aborting", filename);
 240
 241     if (mailbuf[0] == '-')
 242         perrx("Illegal mail name %s in %s", mailbuf, filename);
 243
 244     mailname = mailbuf;
 245
 246     if (nuid != uid)
 247         perrx("Job %s - userid %ld does not match file uid %lu",
 248                 filename, nuid, (unsigned long)uid);
 249
 250     if (ngid != gid)
 251         perrx("Job %s - groupid %ld does not match file gid %lu",
 252                 filename, ngid, (unsigned long)gid);
 253
 254     fclose(stream);
 255
 256     if (chdir(ATSPOOL_DIR) < 0)
 257         perr("cannot chdir to %s", ATSPOOL_DIR);
 258
 259     /* Create a file to hold the output of the job we are about to run.
 260      * Write the mail header.
 261      */
 262     if((fd_out=open(filename,
 263                 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0)
 264         perr("cannot create output file");
 265
 266     write_string(fd_out, "Subject: Output from your job ");
 267     write_string(fd_out, filename);
 268     write_string(fd_out, "\n\n");
 269     fstat(fd_out, &buf);
 270     size = buf.st_size;
 271
 272     close(STDIN_FILENO);
 273     close(STDOUT_FILENO);
 274     close(STDERR_FILENO);
 275
 276     pid = fork();
 277     if (pid < 0)
 278         perr("error in fork");
 279
 280     else if (pid == 0)
 281     {
 282         char *nul = NULL;
 283         char **nenvp = &nul;
 284
 285         /* Set up things for the child; we want standard input from the input file,
 286          * and standard output and error sent to our output file.
 287          */
 288
 289         if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0)
 290             perr("error in lseek");
 291
 292         if (dup(fd_in) != STDIN_FILENO)
 293             perr("error in I/O redirection");
 294
 295         if (dup(fd_out) != STDOUT_FILENO)
 296             perr("error in I/O redirection");
 297
 298         if (dup(fd_out) != STDERR_FILENO)
 299             perr("error in I/O redirection");
 300
 301         close(fd_in);
 302         close(fd_out);
 303         if (chdir(ATJOB_DIR) < 0)
 304             perr("cannot chdir to %s", ATJOB_DIR);
 305
 306         queue = *filename;
 307
 308         PRIV_START
 309
 310         nice(tolower(queue) - 'a');
 311
 312 #ifdef LOGIN_CAP
 313         /*
 314          * For simplicity and safety, set all aspects of the user context
 315          * except for a selected subset:  Don't set priority, which was
 316          * set based on the queue file name according to the tradition.
 317          * Don't bother to set environment, including path vars, either
 318          * because it will be discarded anyway.  Although the job file
 319          * should set umask, preset it here just in case.
 320          */
 321         if (setusercontext(NULL, pentry, uid, LOGIN_SETALL &
 322                 ~(LOGIN_SETPRIORITY | LOGIN_SETPATH | LOGIN_SETENV)) != 0)
 323             exit(EXIT_FAILURE); /* setusercontext() logged the error */
 324 #else /* LOGIN_CAP */
 325         if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
 326             perr("cannot change group");
 327
 328         if (initgroups(pentry->pw_name,pentry->pw_gid))
 329             perr("cannot init group access list");
 330
 331         if (setlogin(pentry->pw_name))
 332             perr("cannot set login name");
 333
 334         if (setuid(uid) < 0 || seteuid(uid) < 0)
 335             perr("cannot set user id");
 336 #endif /* LOGIN_CAP */
 337
 338         if (chdir(pentry->pw_dir))
 339                 chdir("/");
 340
 341         if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0)
 342             perr("exec failed for /bin/sh");
 343
 344         PRIV_END
 345     }
 346     /* We're the parent.  Let's wait.
 347      */
 348     close(fd_in);
 349     close(fd_out);
 350     waitpid(pid, (int *) NULL, 0);
 351
 352     /* Send mail.  Unlink the output file first, so it is deleted after
 353      * the run.
 354      */
 355     stat(filename, &buf);
 356     if (open(filename, O_RDONLY) != STDIN_FILENO)
 357         perr("open of jobfile failed");
 358
 359     unlink(filename);
 360     if ((buf.st_size != size) || send_mail)
 361     {
 362         PRIV_START
 363
 364 #ifdef LOGIN_CAP
 365         /*
 366          * This time set full context to run the mailer.
 367          */
 368         if (setusercontext(NULL, pentry, uid, LOGIN_SETALL) != 0)
 369             exit(EXIT_FAILURE); /* setusercontext() logged the error */
 370 #else /* LOGIN_CAP */
 371         if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
 372             perr("cannot change group");
 373
 374         if (initgroups(pentry->pw_name,pentry->pw_gid))
 375             perr("cannot init group access list");
 376
 377         if (setlogin(pentry->pw_name))
 378             perr("cannot set login name");
 379
 380         if (setuid(uid) < 0 || seteuid(uid) < 0)
 381             perr("cannot set user id");
 382 #endif /* LOGIN_CAP */
 383
 384         if (chdir(pentry->pw_dir))
 385                 chdir("/");
 386
 387 #if 1
 388         execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service",
 389                         "-odi", "-oem",
 390                         mailname, (char *) NULL);
 391 #else
 392         execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL);
 393 #endif
 394             perr("exec failed for mail command");
 395
 396         PRIV_END
 397     }
 398     exit(EXIT_SUCCESS);
 399 }
 400
 401 /* Global functions */
 402
 403 /* Needed in gloadavg.c */
 404 void
 405 perr(const char *fmt, ...)
 406 {
 407     const char * const fmtadd = ": %m";
 408     char nfmt[strlen(fmt) + strlen(fmtadd) + 1];
 409     va_list ap;
 410
 411     va_start(ap, fmt);
 412     if (debug)
 413     {
 414         vwarn(fmt, ap);
 415     }
 416     else
 417     {
 418         snprintf(nfmt, sizeof(nfmt), "%s%s", fmt, fmtadd);
 419         vsyslog(LOG_ERR, nfmt, ap);
 420     }
 421     va_end(ap);
 422
 423     exit(EXIT_FAILURE);
 424 }
 425
 426 void
 427 perrx(const char *fmt, ...)
 428 {
 429     va_list ap;
 430
 431     va_start(ap, fmt);
 432     if (debug)
 433         vwarnx(fmt, ap);
 434     else
 435         vsyslog(LOG_ERR, fmt, ap);
 436     va_end(ap);
 437
 438     exit(EXIT_FAILURE);
 439 }
 440
 441 int
 442 main(int argc, char *argv[])
 443 {
 444 /* Browse through  ATJOB_DIR, checking all the jobfiles wether they should
 445  * be executed and or deleted. The queue is coded into the first byte of
 446  * the job filename, the date (in minutes since Eon) as a hex number in the
 447  * following eight bytes, followed by a dot and a serial number.  A file
 448  * which has not been executed yet is denoted by its execute - bit set.
 449  * For those files which are to be executed, run_file() is called, which forks
 450  * off a child which takes care of I/O redirection, forks off another child
 451  * for execution and yet another one, optionally, for sending mail.
 452  * Files which already have run are removed during the next invocation.
 453  */
 454     DIR *spool;
 455     struct dirent *dirent;
 456     struct stat buf;
 457     unsigned long ctm;
 458     unsigned long jobno;
 459     char queue;
 460     time_t now, run_time;
 461     char batch_name[] = "Z2345678901234";
 462     uid_t batch_uid;
 463     gid_t batch_gid;
 464     int c;
 465     int run_batch;
 466     double load_avg = LOADAVG_MX, la;
 467
 468 /* We don't need root privileges all the time; running under uid and gid daemon
 469  * is fine.
 470  */
 471
 472     RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID)
 473
 474     openlog(atrun, LOG_PID, LOG_CRON);
 475
 476     opterr = 0;
 477     while((c=getopt(argc, argv, "dl:"))!= -1)
 478     {
 479         switch (c)
 480         {
 481         case 'l':
 482             if (sscanf(optarg, "%lf", &load_avg) != 1)
 483                 perr("garbled option -l");
 484             if (load_avg <= 0.)
 485                 load_avg = LOADAVG_MX;
 486             break;
 487
 488         case 'd':
 489             debug ++;
 490             break;
 491
 492         case '?':
 493         default:
 494             usage();
 495         }
 496     }
 497
 498     if (chdir(ATJOB_DIR) != 0)
 499         perr("cannot change to %s", ATJOB_DIR);
 500
 501     /* Main loop. Open spool directory for reading and look over all the
 502      * files in there. If the filename indicates that the job should be run
 503      * and the x bit is set, fork off a child which sets its user and group
 504      * id to that of the files and exec a /bin/sh which executes the shell
 505      * script. Unlink older files if they should no longer be run.  For
 506      * deletion, their r bit has to be turned on.
 507      *
 508      * Also, pick the oldest batch job to run, at most one per invocation of
 509      * atrun.
 510      */
 511     if ((spool = opendir(".")) == NULL)
 512         perr("cannot read %s", ATJOB_DIR);
 513
 514     now = time(NULL);
 515     run_batch = 0;
 516     batch_uid = (uid_t) -1;
 517     batch_gid = (gid_t) -1;
 518
 519     while ((dirent = readdir(spool)) != NULL) {
 520         if (stat(dirent->d_name,&buf) != 0)
 521             perr("cannot stat in %s", ATJOB_DIR);
 522
 523         /* We don't want directories
 524          */
 525         if (!S_ISREG(buf.st_mode))
 526             continue;
 527
 528         if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3)
 529             continue;
 530
 531         run_time = (time_t) ctm*60;
 532
 533         if ((S_IXUSR & buf.st_mode) && (run_time <=now)) {
 534             if ((isupper(queue) || queue == 'b') && (strcmp(batch_name,dirent->d_name) > 0)) {
 535                 run_batch = 1;
 536                 strlcpy(batch_name, dirent->d_name, sizeof(batch_name));
 537                 batch_uid = buf.st_uid;
 538                 batch_gid = buf.st_gid;
 539             }
 540
 541         /* The file is executable and old enough
 542          */
 543             if (islower(queue))
 544                 run_file(dirent->d_name, buf.st_uid, buf.st_gid);
 545         }
 546         /*  Delete older files
 547          */
 548         if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode))
 549             unlink(dirent->d_name);
 550     }
 551     /* run the single batch file, if any
 552     */
 553     if (run_batch && (getloadavg(&la, 1) == 1) && la < load_avg)
 554         run_file(batch_name, batch_uid, batch_gid);
 555
 556     closelog();
 557 #if __APPLE__
 558     // allow enough time for child processes to call setsid(2)
 559     sleep(1);
 560 #endif
 561     exit(EXIT_SUCCESS);
 562 }
 563
 564 static void
 565 usage(void)
 566 {
 567     if (debug)
 568         fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n");
 569     else
 570         syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]");
 571
 572     exit(EXIT_FAILURE);
 573 }