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Close security holes reported.
This commit is contained in:
Andrey A. Chernov 1995-04-12 02:52:21 +00:00
parent b89321a57d
commit c70e5825aa
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=7768
3 changed files with 427 additions and 247 deletions
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24
libexec/atrun/Makefile
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@ -1,13 +1,25 @@
# $Id: Makefile,v 1.2 1993/12/05 12:26:10 cgd Exp $
# $Id: Makefile,v 1.1 1994/01/05 01:02:56 nate Exp $
MAINSRC= ${.CURDIR}/../../usr.bin/at
.include "$(MAINSRC)/Makefile.inc"
PROG= atrun
MAN8= atrun.8
BINDIR= /usr/libexec
BINOWN= root
BINDIR= $(ATLIB_DIR)
MANSRC= .
CLEANFILES += ${MAN8}
MANDEPEND = ${MAN8}
CFLAGS+= -I${.CURDIR}/../../usr.bin/at
LDADD+= -lutil
DPADD+= ${LIBUTIL}
CFLAGS+= -I$(MAINSRC)
${MAN8}: atrun.man
sed -e \
"s@_ATSPOOL_DIR@$(ATSPOOL_DIR)@g; \
s@_ATJOB_DIR@$(ATJOB_DIR)@g; \
s@_ATLIB_DIR@$(ATLIB_DIR)@g; \
s@_LOADAVG_MX@$(LOADAVG_MX)@g;" \
< $? > $@
.include <bsd.prog.mk>

584
libexec/atrun/atrun.c
View File

@ -1,7 +1,6 @@
/*
* atrun.c - run jobs queued by at; run with root privileges.
* Copyright (c) 1993 by Thomas Koenig
* All rights reserved.
/*
* atrun.c - run jobs queued by at; run with root privileges.
* 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
@ -30,9 +29,11 @@
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <ctype.h>
#include <dirent.h>
#include <errno.h>
#include <pwd.h>
#include <grp.h>
#include <signal.h>
#include <stddef.h>
#include <stdio.h>
@ -41,287 +42,388 @@
#include <time.h>
#include <unistd.h>
#include <syslog.h>
#ifndef __FreeBSD__
#include <getopt.h>
#else
#include <paths.h>
#endif
/* Local headers */
#ifndef __FreeBSD__
#include "gloadavg.h"
#endif
#define MAIN
#include "privs.h"
#include "pathnames.h"
#include "atrun.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 char *namep;
static char rcsid[] = "$Id: atrun.c,v 1.1 1993/12/05 11:36:38 cgd Exp $";
static char rcsid[] = "$Id: atrun.c,v 1.1 1994/05/10 18:23:08 kernel Exp $";
static debug = 0;
/* Local functions */
static void
perr(a)
const char *a;
perr(const char *a)
{
if (debug)
{
perror(a);
}
else
syslog(LOG_ERR, "%s: %m", a);
exit(EXIT_FAILURE);
exit(EXIT_FAILURE);
}
static int
write_string(fd, a)
int fd;
const char *a;
write_string(int fd, const char* a)
{
return write(fd, a, strlen(a));
return write(fd, a, strlen(a));
}
static void
run_file(filename, uid, gid)
const char *filename;
uid_t uid;
gid_t gid;
#ifdef DEBUG_FORK
static pid_t
myfork()
{
/*
* Run a file by by spawning off a process which redirects I/O,
* spawns a subshell, then waits for it to complete and spawns another
* process to send mail to the user.
*/
pid_t pid;
int fd_out, fd_in;
int queue;
char mailbuf[9];
char *mailname = NULL;
FILE *stream;
int send_mail = 0;
struct stat buf;
off_t size;
struct passwd *pentry;
int fflags;
pid_t res;
res = fork();
if (res == 0)
kill(getpid(),SIGSTOP);
return res;
}
pid = fork();
if (pid == -1)
perr("Cannot fork");
else if (pid > 0)
return;
#define fork myfork
#endif
/*
* 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.
static void
run_file(const char *filename, uid_t uid, gid_t gid)
{
/* Run a file by 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[9];
char *mailname = NULL;
FILE *stream;
int send_mail = 0;
struct stat buf;
off_t size;
struct passwd *pentry;
int fflags;
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)
{
syslog(LOG_ERR,"Userid %lu not found - aborting job %s",
(unsigned long) uid, filename);
exit(EXIT_FAILURE);
}
PRIV_START
stream=fopen(filename, "r");
PRIV_END
if (stream == NULL)
perr("Cannot open input file");
if ((fd_in = dup(fileno(stream))) <0)
perr("Error duplicating input file descriptor");
if ((fflags = fcntl(fd_in, F_GETFD)) <0)
perr("Error in fcntl");
fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
if (fscanf(stream, "#! /bin/sh\n# mail %8s %d", mailbuf, &send_mail) == 2)
{
mailname = mailbuf;
pentry = getpwnam(mailname);
if (pentry == NULL || pentry->pw_uid != uid) {
syslog(LOG_ERR,"Userid %lu mismatch name %s - aborting job %s",
(unsigned long) uid, mailname, filename);
exit(EXIT_FAILURE);
}
}
else
{
mailname = pentry->pw_name;
}
fclose(stream);
if (chdir(ATSPOOL_DIR) < 0)
perr("Cannot chdir to " 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 " ATJOB_DIR);
queue = *filename;
PRIV_START
stream = fopen(filename, "r");
nice(tolower(queue) - 'a');
chdir(pentry->pw_dir);
if (initgroups(pentry->pw_name,pentry->pw_gid))
perr("Cannot delete saved userids");
if (setgid(gid) < 0)
perr("Cannot change group");
if (setuid(uid) < 0)
perr("Cannot set user id");
if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0)
perr("Exec failed");
PRIV_END
}
/* We're the parent. Let's wait.
*/
close(fd_in);
close(fd_out);
waitpid(pid, (int *) NULL, 0);
if (stream == NULL)
perr("Cannot open input file");
/* 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");
if ((fd_in = dup(fileno(stream))) < 0)
perr("Error duplicating input file descriptor");
if ((fflags = fcntl(fd_in, F_GETFD)) < 0)
perr("Error in fcntl");
fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
if (fscanf(stream, "#! /bin/sh\n# mail %8s %d", mailbuf, &send_mail) == 2) {
mailname = mailbuf;
} else {
pentry = getpwuid(uid);
if (pentry == NULL)
mailname = "root";
else
mailname = pentry->pw_name;
}
fclose(stream);
if (chdir(_PATH_ATSPOOL) < 0)
perr("Cannot chdir to " _PATH_ATSPOOL);
/*
* 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(_PATH_ATJOBS) < 0)
perr("Cannot chdir to " _PATH_ATJOBS);
queue = *filename;
PRIV_START
if (queue > 'b')
nice(queue - 'b');
if (setgid(gid) < 0)
perr("Cannot change group");
if (setuid(uid) < 0)
perr("Cannot set user id");
chdir("/");
if (execle("/bin/sh", "sh", (char *) NULL, nenvp) != 0)
perr("Exec failed");
PRIV_END
}
/* We're the parent. Let's wait. */
close(fd_in);
close(fd_out);
waitpid(pid, (int *) NULL, 0);
stat(filename, &buf);
if ((buf.st_size != size) || send_mail) {
/* Fork off a child for sending mail */
pid = fork();
if (pid < 0)
perr("Fork failed");
else if (pid == 0) {
if (open(filename, O_RDONLY) != STDIN_FILENO)
perr("Cannot reopen output file");
execl(_PATH_SENDMAIL, _PATH_SENDMAIL, mailname,
(char *) NULL);
perr("Exec failed");
}
waitpid(pid, (int *) NULL, 0);
}
unlink(filename);
exit(EXIT_SUCCESS);
unlink(filename);
if ((buf.st_size != size) || send_mail)
{
#ifdef __FreeBSD__
execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service",
mailname, (char *) NULL);
#else
execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL);
#endif
perr("Exec failed");
}
exit(EXIT_SUCCESS);
}
/* Global functions */
int
main(argc, argv)
int argc;
char *argv[];
main(int argc, char *argv[])
{
/*
* Browse through _PATH_ATJOBS, 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;
int older;
unsigned long ctm;
char queue;
/* 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;
char queue;
time_t now, run_time;
char batch_name[] = "Z2345678901234";
uid_t batch_uid;
gid_t batch_gid;
int c;
int run_batch;
double load_avg = LOADAVG_MX;
/*
* We don't need root privileges all the time; running under uid
* and gid daemon is fine.
*/
/* We don't need root privileges all the time; running under uid and gid daemon
* is fine.
*/
RELINQUISH_PRIVS_ROOT(0) /* it's setuid root */
openlog("atrun", LOG_PID, LOG_CRON);
RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID)
namep = argv[0];
if (chdir(_PATH_ATJOBS) != 0)
perr("Cannot change to " _PATH_ATJOBS);
openlog("atrun", LOG_PID, LOG_CRON);
/*
* 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.
*/
if ((spool = opendir(".")) == NULL)
perr("Cannot read " _PATH_ATJOBS);
opterr = 0;
errno = 0;
while((c=getopt(argc, argv, "dl:"))!= EOF)
{
switch (c)
{
case 'l':
if (sscanf(optarg, "%lf", &load_avg) != 1)
perr("garbled option -l");
if (load_avg <= 0.)
load_avg = LOADAVG_MX;
break;
while ((dirent = readdir(spool)) != NULL) {
double la;
case 'd':
debug ++;
break;
if (stat(dirent->d_name, &buf) != 0)
perr("Cannot stat in " _PATH_ATJOBS);
case '?':
perr("unknown option");
break;
/* We don't want directories */
if (!S_ISREG(buf.st_mode))
continue;
if (sscanf(dirent->d_name, "%c%8lx", &queue, &ctm) != 2)
continue;
if ((queue == 'b') && ((getloadavg(&la, 1) != 1) ||
(la > ATRUN_MAXLOAD)))
continue;
older = (time_t) ctm *60 <= time(NULL);
/* The file is executable and old enough */
if (older && (S_IXUSR & buf.st_mode)) {
/*
* Now we know we want to run the file, we can turn
* off the execute bit
*/
PRIV_START
if (chmod(dirent->d_name, S_IRUSR) != 0)
perr("Cannot change file permissions");
PRIV_END
run_file(dirent->d_name, buf.st_uid, buf.st_gid);
}
/* Delete older files */
if (older && !(S_IXUSR & buf.st_mode) &&
(S_IRUSR & buf.st_mode))
unlink(dirent->d_name);
default:
perr("idiotic option - aborted");
break;
}
closelog();
exit(EXIT_SUCCESS);
}
namep = argv[0];
if (chdir(ATJOB_DIR) != 0)
perr("Cannot change to " ATJOB_DIR);
/* 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 " 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 " ATJOB_DIR);
/* We don't want directories
*/
if (!S_ISREG(buf.st_mode))
continue;
if (sscanf(dirent->d_name,"%c%8lx",&queue,&ctm) != 2)
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;
strncpy(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
*/
#ifndef __FreeBSD__
if (run_batch && (gloadavg() < load_avg)) {
#else
if (run_batch) {
double la;
if (getloadavg(&la, 1) != 1)
perr("Error in getloadavg");
if (la < load_avg)
#endif
run_file(batch_name, batch_uid, batch_gid);
}
closelog();
exit(EXIT_SUCCESS);
}

66
libexec/atrun/atrun.man Normal file
View File

@ -0,0 +1,66 @@
.\" $Id: atrun.man,v 1.1 1994/05/10 18:23:08 kernel Exp $
.Dd April 12, 1995
.Dt ATRUN 8
.Os "FreeBSD 2.1"
.Sh NAME
.Nm atrun
.Nd run jobs queued for later execution
.Sh SYNOPSIS
.Nm atrun
.Op Fl l Ar load_avg
.Op Fl d
.Sh DESCRIPTION
.Nm Atrun
runs jobs queued by
.Xr at 1 .
Root's
.Xr crontab 5
file
.Pa /etc/crontab
has to contain the line
.nf
*/5 * * * * root _ATLIB_DIR/atrun
.fi
so
.Xr atrun 8
gets called every five minutes.
.Pp
At every invocation, every job in lowercase queues whose starting time
has passed is started.
A maximum of one batch jobs (denoted by uppercase queues) are started
each time
.Nm atrun
is invoked.
.Sh OPTIONS
.Bl -tag -width indent
.It Fl l Ar load_avg
Specifies a limiting load factor, over which batch jobs should
not be run, instead of the compiled \- in value of _LOADAVG_MX.
.It Fl d
Debug; print error messages to standard error instead of using
.Xr syslog 3 .
.El
.Sh WARNINGS
For
.Nm atrun
to work, you have to start up a
.Xr cron 8
daemon.
.Sh FILES
.Bl -tag -width _ATSPOOL_DIR -compact
.It Pa _ATSPOOL_DIR
Directory containing output spool files
.It Pa _ATJOB_DIR
Directory containing job files
.El
.Sh SEE ALSO
.Xr cron 8 ,
.Xr crontab 1 ,
.Xr crontab 5 ,
.Xr at 1 ,
.Xr syslog 3 .
.Sh BUGS
The functionality of
.Nm atrun
should be merged into
.Xr cron 8 .