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freebsd-src/libexec/atrun/atrun.c
Pedro F. Giffuni e6209940de libexec: adoption of SPDX licensing ID tags. 
Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

No functional change intended.
2017-11-27 15:25:02 +00:00

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/*-
* atrun.c - run jobs queued by at; run with root privileges.
*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (C) 1993, 1994 Thomas Koenig
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. The name of the author(s) may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef lint
static const char rcsid[] =
"$FreeBSD$";
#endif /* not lint */
/* System Headers */
#include <sys/fcntl.h>
#include <sys/file.h>
#include <sys/types.h>
#include <sys/stat.h>
#ifdef __FreeBSD__
#include <sys/sysctl.h>
#endif
#include <sys/wait.h>
#include <sys/param.h>
#include <ctype.h>
#include <dirent.h>
#include <err.h>
#include <grp.h>
#include <pwd.h>
#include <signal.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <time.h>
#include <unistd.h>
#ifdef __FreeBSD__
#include <paths.h>
#else
#include <getopt.h>
#endif
#ifdef LOGIN_CAP
#include <login_cap.h>
#endif
#ifdef PAM
#include <security/pam_appl.h>
#include <security/openpam.h>
#endif
/* Local headers */
#include "gloadavg.h"
#define MAIN
#include "privs.h"
/* Macros */
#ifndef ATJOB_DIR
#define ATJOB_DIR "/usr/spool/atjobs/"
#endif
#ifndef ATSPOOL_DIR
#define ATSPOOL_DIR "/usr/spool/atspool/"
#endif
#ifndef LOADAVG_MX
#define LOADAVG_MX 1.5
#endif
/* File scope variables */
static const char * const atrun = "atrun"; /* service name for syslog etc. */
static int debug = 0;
void perr(const char *fmt, ...);
void perrx(const char *fmt, ...);
static void usage(void);
/* Local functions */
static int
write_string(int fd, const char* a)
{
return write(fd, a, strlen(a));
}
#undef DEBUG_FORK
#ifdef DEBUG_FORK
static pid_t
myfork(void)
{
pid_t res;
res = fork();
if (res == 0)
kill(getpid(),SIGSTOP);
return res;
}
#define fork myfork
#endif
static void
run_file(const char *filename, uid_t uid, gid_t gid)
{
/* Run a file by spawning off a process which redirects I/O,
* spawns a subshell, then waits for it to complete and sends
* mail to the user.
*/
pid_t pid;
int fd_out, fd_in;
int queue;
char mailbuf[MAXLOGNAME], fmt[64];
char *mailname = NULL;
FILE *stream;
int send_mail = 0;
struct stat buf, lbuf;
off_t size;
struct passwd *pentry;
int fflags;
long nuid;
long ngid;
#ifdef PAM
pam_handle_t *pamh = NULL;
int pam_err;
struct pam_conv pamc = {
.conv = openpam_nullconv,
.appdata_ptr = NULL
};
#endif
PRIV_START
if (chmod(filename, S_IRUSR) != 0)
{
perr("cannot change file permissions");
}
PRIV_END
pid = fork();
if (pid == -1)
perr("cannot fork");
else if (pid != 0)
return;
/* Let's see who we mail to. Hopefully, we can read it from
* the command file; if not, send it to the owner, or, failing that,
* to root.
*/
pentry = getpwuid(uid);
if (pentry == NULL)
perrx("Userid %lu not found - aborting job %s",
(unsigned long) uid, filename);
#ifdef PAM
PRIV_START
pam_err = pam_start(atrun, pentry->pw_name, &pamc, &pamh);
if (pam_err != PAM_SUCCESS)
perrx("cannot start PAM: %s", pam_strerror(pamh, pam_err));
pam_err = pam_acct_mgmt(pamh, PAM_SILENT);
/* Expired password shouldn't prevent the job from running. */
if (pam_err != PAM_SUCCESS && pam_err != PAM_NEW_AUTHTOK_REQD)
perrx("Account %s (userid %lu) unavailable for job %s: %s",
pentry->pw_name, (unsigned long)uid,
filename, pam_strerror(pamh, pam_err));
pam_end(pamh, pam_err);
PRIV_END
#endif /* PAM */
PRIV_START
stream=fopen(filename, "r");
PRIV_END
if (stream == NULL)
perr("cannot open input file %s", filename);
if ((fd_in = dup(fileno(stream))) <0)
perr("error duplicating input file descriptor");
if (fstat(fd_in, &buf) == -1)
perr("error in fstat of input file descriptor");
if (lstat(filename, &lbuf) == -1)
perr("error in fstat of input file");
if (S_ISLNK(lbuf.st_mode))
perrx("Symbolic link encountered in job %s - aborting", filename);
if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) ||
(lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) ||
(lbuf.st_size!=buf.st_size))
perrx("Somebody changed files from under us for job %s - aborting",
filename);
if (buf.st_nlink > 1)
perrx("Somebody is trying to run a linked script for job %s", filename);
if ((fflags = fcntl(fd_in, F_GETFD)) <0)
perr("error in fcntl");
fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
snprintf(fmt, sizeof(fmt),
"#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d",
MAXLOGNAME - 1);
if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4)
perrx("File %s is in wrong format - aborting", filename);
if (mailbuf[0] == '-')
perrx("Illegal mail name %s in %s", mailbuf, filename);
mailname = mailbuf;
if (nuid != uid)
perrx("Job %s - userid %ld does not match file uid %lu",
filename, nuid, (unsigned long)uid);
if (ngid != gid)
perrx("Job %s - groupid %ld does not match file gid %lu",
filename, ngid, (unsigned long)gid);
fclose(stream);
if (chdir(ATSPOOL_DIR) < 0)
perr("cannot chdir to %s", ATSPOOL_DIR);
/* Create a file to hold the output of the job we are about to run.
* Write the mail header.
*/
if((fd_out=open(filename,
O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0)
perr("cannot create output file");
write_string(fd_out, "Subject: Output from your job ");
write_string(fd_out, filename);
write_string(fd_out, "\n\n");
fstat(fd_out, &buf);
size = buf.st_size;
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);
pid = fork();
if (pid < 0)
perr("error in fork");
else if (pid == 0)
{
char *nul = NULL;
char **nenvp = &nul;
/* Set up things for the child; we want standard input from the input file,
* and standard output and error sent to our output file.
*/
if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0)
perr("error in lseek");
if (dup(fd_in) != STDIN_FILENO)
perr("error in I/O redirection");
if (dup(fd_out) != STDOUT_FILENO)
perr("error in I/O redirection");
if (dup(fd_out) != STDERR_FILENO)
perr("error in I/O redirection");
close(fd_in);
close(fd_out);
if (chdir(ATJOB_DIR) < 0)
perr("cannot chdir to %s", ATJOB_DIR);
queue = *filename;
PRIV_START
nice(tolower(queue) - 'a');
#ifdef LOGIN_CAP
/*
* For simplicity and safety, set all aspects of the user context
* except for a selected subset: Don't set priority, which was
* set based on the queue file name according to the tradition.
* Don't bother to set environment, including path vars, either
* because it will be discarded anyway. Although the job file
* should set umask, preset it here just in case.
*/
if (setusercontext(NULL, pentry, uid, LOGIN_SETALL &
~(LOGIN_SETPRIORITY | LOGIN_SETPATH | LOGIN_SETENV)) != 0)
exit(EXIT_FAILURE); /* setusercontext() logged the error */
#else /* LOGIN_CAP */
if (initgroups(pentry->pw_name,pentry->pw_gid))
perr("cannot init group access list");
if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
perr("cannot change group");
if (setlogin(pentry->pw_name))
perr("cannot set login name");
if (setuid(uid) < 0 || seteuid(uid) < 0)
perr("cannot set user id");
#endif /* LOGIN_CAP */
if (chdir(pentry->pw_dir))
chdir("/");
if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0)
perr("exec failed for /bin/sh");
PRIV_END
}
/* We're the parent. Let's wait.
*/
close(fd_in);
close(fd_out);
waitpid(pid, (int *) NULL, 0);
/* Send mail. Unlink the output file first, so it is deleted after
* the run.
*/
stat(filename, &buf);
if (open(filename, O_RDONLY) != STDIN_FILENO)
perr("open of jobfile failed");
unlink(filename);
if ((buf.st_size != size) || send_mail)
{
PRIV_START
#ifdef LOGIN_CAP
/*
* This time set full context to run the mailer.
*/
if (setusercontext(NULL, pentry, uid, LOGIN_SETALL) != 0)
exit(EXIT_FAILURE); /* setusercontext() logged the error */
#else /* LOGIN_CAP */
if (initgroups(pentry->pw_name,pentry->pw_gid))
perr("cannot init group access list");
if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0)
perr("cannot change group");
if (setlogin(pentry->pw_name))
perr("cannot set login name");
if (setuid(uid) < 0 || seteuid(uid) < 0)
perr("cannot set user id");
#endif /* LOGIN_CAP */
if (chdir(pentry->pw_dir))
chdir("/");
#ifdef __FreeBSD__
execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service",
"-odi", "-oem",
mailname, (char *) NULL);
#else
execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL);
#endif
perr("exec failed for mail command");
PRIV_END
}
exit(EXIT_SUCCESS);
}
/* Global functions */
/* Needed in gloadavg.c */
void
perr(const char *fmt, ...)
{
const char * const fmtadd = ": %m";
char nfmt[strlen(fmt) + strlen(fmtadd) + 1];
va_list ap;
va_start(ap, fmt);
if (debug)
{
vwarn(fmt, ap);
}
else
{
snprintf(nfmt, sizeof(nfmt), "%s%s", fmt, fmtadd);
vsyslog(LOG_ERR, nfmt, ap);
}
va_end(ap);
exit(EXIT_FAILURE);
}
void
perrx(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
if (debug)
vwarnx(fmt, ap);
else
vsyslog(LOG_ERR, fmt, ap);
va_end(ap);
exit(EXIT_FAILURE);
}
int
main(int argc, char *argv[])
{
/* Browse through ATJOB_DIR, checking all the jobfiles wether they should
* be executed and or deleted. The queue is coded into the first byte of
* the job filename, the date (in minutes since Eon) as a hex number in the
* following eight bytes, followed by a dot and a serial number. A file
* which has not been executed yet is denoted by its execute - bit set.
* For those files which are to be executed, run_file() is called, which forks
* off a child which takes care of I/O redirection, forks off another child
* for execution and yet another one, optionally, for sending mail.
* Files which already have run are removed during the next invocation.
*/
DIR *spool;
struct dirent *dirent;
struct stat buf;
unsigned long ctm;
unsigned long jobno;
char queue;
time_t now, run_time;
char batch_name[] = "Z2345678901234";
uid_t batch_uid;
gid_t batch_gid;
int c;
int run_batch;
#ifdef __FreeBSD__
size_t ncpusz;
double load_avg = -1;
int ncpu;
#else
double load_avg = LOADAVG_MX;
#endif
/* We don't need root privileges all the time; running under uid and gid daemon
* is fine.
*/
RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID)
openlog(atrun, LOG_PID, LOG_CRON);
opterr = 0;
while((c=getopt(argc, argv, "dl:"))!= -1)
{
switch (c)
{
case 'l':
if (sscanf(optarg, "%lf", &load_avg) != 1)
perr("garbled option -l");
#ifndef __FreeBSD__
if (load_avg <= 0.)
load_avg = LOADAVG_MX;
#endif
break;
case 'd':
debug ++;
break;
case '?':
default:
usage();
}
}
if (chdir(ATJOB_DIR) != 0)
perr("cannot change to %s", ATJOB_DIR);
#ifdef __FreeBSD__
if (load_avg <= 0.) {
ncpusz = sizeof(size_t);
if (sysctlbyname("hw.ncpu", &ncpu, &ncpusz, NULL, 0) < 0)
ncpu = 1;
load_avg = LOADAVG_MX * ncpu;
}
#endif
/* Main loop. Open spool directory for reading and look over all the
* files in there. If the filename indicates that the job should be run
* and the x bit is set, fork off a child which sets its user and group
* id to that of the files and exec a /bin/sh which executes the shell
* script. Unlink older files if they should no longer be run. For
* deletion, their r bit has to be turned on.
*
* Also, pick the oldest batch job to run, at most one per invocation of
* atrun.
*/
if ((spool = opendir(".")) == NULL)
perr("cannot read %s", ATJOB_DIR);
if (flock(dirfd(spool), LOCK_EX) == -1)
perr("cannot lock %s", ATJOB_DIR);
now = time(NULL);
run_batch = 0;
batch_uid = (uid_t) -1;
batch_gid = (gid_t) -1;
while ((dirent = readdir(spool)) != NULL) {
if (stat(dirent->d_name,&buf) != 0)
perr("cannot stat in %s", ATJOB_DIR);
/* We don't want directories
*/
if (!S_ISREG(buf.st_mode))
continue;
if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3)
continue;
run_time = (time_t) ctm*60;
if ((S_IXUSR & buf.st_mode) && (run_time <=now)) {
if (isupper(queue) && (strcmp(batch_name,dirent->d_name) > 0)) {
run_batch = 1;
strlcpy(batch_name, dirent->d_name, sizeof(batch_name));
batch_uid = buf.st_uid;
batch_gid = buf.st_gid;
}
/* The file is executable and old enough
*/
if (islower(queue))
run_file(dirent->d_name, buf.st_uid, buf.st_gid);
}
/* Delete older files
*/
if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode))
unlink(dirent->d_name);
}
/* run the single batch file, if any
*/
if (run_batch && (gloadavg() < load_avg))
run_file(batch_name, batch_uid, batch_gid);
if (flock(dirfd(spool), LOCK_UN) == -1)
perr("cannot unlock %s", ATJOB_DIR);
if (closedir(spool) == -1)
perr("cannot closedir %s", ATJOB_DIR);
closelog();
exit(EXIT_SUCCESS);
}
static void
usage(void)
{
if (debug)
fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n");
else
syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]");
exit(EXIT_FAILURE);
}
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