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/*++
/* NAME
/* chrootuid 1
/* SUMMARY
/* run command in restricted environment
/* SYNOPSIS
/* \fBchrootuid\fR \fInewroot newuser command\fR...
/* DESCRIPTION
/* The \fBchrootuid\fR command sets up a restricted environment for
/* executing \fIcommand\fR. Access to the file system is restricted to
/* the \fInewroot\fR subtree; privileges are restricted to those of
/* the \fInewuser\fR account (which must be a known account in the
/* unrestricted environment).
/* The initial working directory is changed to \fInewroot\fR.
/*
/* \fBchrootuid\fR combines chroot(8) and su(1) into one program, so
/* that there is no need to have commands such as /usr/bin/su
/* in the restricted environment.
/*
/* Only the superuser can use the \fBchrootuid\fR command.
/* DIAGNOSTICS
/* The exit status is 1 when \fBchrootuid\fR has a problem, otherwise
/* the exit status is the exit status of \fIcommand\fR.
/* SEE ALSO
/* chroot(8), su(1)
/* DIAGNOSTICS
/* Problems are reported to the syslog daemon.
/* AUTHOR(S)
/* Wietse Venema
/* Eindhoven University of Technology
/* Department of Mathematics and Computer Science
/* Den Dolech 2, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
/*
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/* CREATION DATE
/* Tue Oct 13 11:37:29 MET 1992
/* LAST MODIFICATION
/* Wed Jul 25 11:25:08 EDT 2001
/* VERSION/RELEASE
/* 1.3
/*--*/
#ifndef lint
static char sccsid[] = "@(#) chrootuid.c 1.3 2001/07/25 11:25:08";
#endif
/* System libraries. */
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <pwd.h>
#include <grp.h>
#include <syslog.h>
extern char *optarg;
extern int optind, opterr, optopt;
int main(argc, argv)
int argc;
char **argv;
{
struct passwd *pwd;
int interactive = 1;
int optstart = 0;
/*
* Open a channel to the syslog daemon. Older versions of openlog()
* require only two arguments.
*/
#ifdef LOG_DAEMON
(void) openlog(argv[0], LOG_PID | LOG_NDELAY, LOG_DAEMON);
#else
(void) openlog(argv[0], LOG_PID);
#endif
/*
* Require proper amount of arguments. In all cases of error, exit with
* zero status because we have already reported the problem via syslogd.
* No need to make inetd complain, too.
*/
/* If we use -i, skip it over and increment optstart */
/* we cannot use the getopt library using:
* if (getopt(argc, argv, "i") != -1) {
* in order to preserve the arguments provided to the command
* This means that -i must be the *first* (and only) argument */
if ( argv[1] != NULL && strncmp(argv[1], "-i", 2) == 0 ) {
interactive = 0;
optstart++;
}
if (argc-optstart < 4) {
if (interactive) {
syslog(LOG_ERR, "usage: %s [-i] path user command", argv[0]);
} else {
fprintf(stderr,"usage: %s [-i] path user command\n", argv[0]);
return (1);
}
return (0);
}
/* Must step into the new subtree. */
if (chdir(argv[1+optstart])) {
if (interactive) {
syslog(LOG_ERR, "chdir(%s): %m", argv[1+optstart]);
return (0);
} else {
fprintf(stderr, "chdir(%s): %s\n", argv[1+optstart], strerror(errno));
return (1);
}
}
/* The user must be known in the *unrestricted* universe... */
if ((pwd = getpwnam(argv[2+optstart])) == 0) {
if (interactive) {
syslog(LOG_ERR, "%s: user unknown", argv[2+optstart]);
return (0);
} else {
fprintf(stderr, "%s: user unknown\n", argv[2+optstart]);
return (1);
}
}
/* initgroups() accesses the group file in the unrestricted universe... */
if (initgroups(pwd->pw_name, pwd->pw_gid) < 0) {
if (interactive) {
syslog(LOG_ERR, "initgroups: %m");
return (0);
} else {
fprintf(stderr, "initgroups: %s\n", strerror(errno));
return (1);
}
}
endgrent();
/* Do the chroot() before giving away root privileges. */
if (chroot(argv[1+optstart])) {
if (interactive) {
syslog(LOG_ERR, "chroot(%s): %m", argv[1+optstart]);
return (0);
} else {
fprintf(stderr, "chroot(%s): %s\n", argv[1+optstart], strerror(errno));
return (1);
}
}
/* Switch group id then user id. */
if (setgid(pwd->pw_gid)) {
if (interactive) {
syslog(LOG_ERR, "setgid(%d): %m", pwd->pw_gid);
return (0);
} else {
fprintf(stderr, "setgid(%d): %s\n", pwd->pw_gid, strerror(errno));
return (1);
}
}
if (setuid(pwd->pw_uid)) {
if (interactive) {
syslog(LOG_ERR, "setuid(%d): %m", pwd->pw_uid);
return (0);
} else {
fprintf(stderr, "setuid(%d): %s\n", pwd->pw_uid, strerror(errno));
return (1);
}
}
/* In case we still have the /etc/passwd file still open. */
endpwent();
/* Run the command and hope for the best. */
(void) execv(argv[3+optstart], argv + 3+optstart);
if (interactive) {
syslog(LOG_ERR, "%s: %m", argv[3+optstart]);
return (0);
}
fprintf(stderr, "%s: %s", argv[3+optstart], strerror(errno));
return (1);
}
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