/* python-setuid.c - Wrapper for execution of Python setuid scripts
 * Copyright (C) 2003 Domenico Andreoli
 *
 * python-setuid.c is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * python-setuid.c is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Prua; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#define PYTHON "/usr/local/bin/python2.4"
#define FULLPATH "/var/qmail/plugins/vmgrucheck.py"

#ifndef PYTHON
#error "This wrapper requires PYTHON macro be defined to specify which Python interpreter is to be used."
#endif
#ifndef FULLPATH
#error "This wrapper requires FULLPATH macro be defined to specify which Python script is to be wrapped."
#endif

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/resource.h>
#include <string.h>
#include <stdarg.h>
#include <errno.h>

#if defined(__STDC__) && defined(__sgi)
#define environ _environ
#endif

static char python[] = PYTHON;
static char fullpath[] = FULLPATH;

static char def_IFS[] = "IFS= \t\n";
static char def_CDPATH[] = "CDPATH=.";
static char def_ENV[] = "ENV=:";
static char def_PATH[] = "PATH=/usr/bin:/bin"; /* :/usr/bin/local"; */

static void die(const char *fmt, ...)
{
	va_list ap;
	va_start(ap, fmt);
	vfprintf(stderr, fmt, ap);
	va_end(ap);
	exit(1);
}

/*
 * This function changes all environment variables that start with LD_
 * into variables that start with XD_.  This is important since we
 * don't want the script that is executed to use any funny shared
 * libraries.
 *
 * If IFS is set in the environment, set it to space,tab,newline.
 * If CDPATH is set in the environment, set it to ".".
 * Set PATH to a reasonable default.
 */
static void clean_environ(void)
{
	char **p;
	extern char **environ;

	for(p = environ; *p; p++) {
		if(strncmp(*p, "LD_", 3) == 0)
			**p = 'X';
		else if(strncmp(*p, "_RLD", 4) == 0)
			**p = 'X';
		else if(strncmp(*p, "PYTHON", 6) == 0)
			**p = 'X';
		else if(strncmp(*p, "IFS=", 4) == 0)
			*p = def_IFS;
		else if(strncmp(*p, "CDPATH=", 7) == 0)
			*p = def_CDPATH;
		else if(strncmp(*p, "ENV=", 4) == 0)
			*p = def_ENV;
	}
	putenv(def_PATH);
}

int main(int argc, char *argv[])
{
	int i;
	char **args, **a;

	struct stat statb;
	struct rlimit rlim;
	
	const gid_t egid = getegid();
	const uid_t euid = geteuid();

	args = (char**) malloc((argc+3) * sizeof(char*));
	if(args == NULL)
		die("%s: malloc: %s\n", argv[0], strerror(errno));
	
	a = args;
	*(a++) = python;

	if(euid != getuid() || egid != getgid()) {	
		if(fullpath[0] != '/')
			die("%s: not a full path name: %s\n", argv[0], fullpath);
		
		if(stat(fullpath, &statb) < 0)
			die("%s: stat: %s\n", argv[0], strerror(errno));
		if(statb.st_uid != 0 && statb.st_uid != euid)
			die("%s: wrong owner: %s\n", argv[0], fullpath);

		clean_environ();

		umask(077);

		rlim.rlim_cur = 0;
		rlim.rlim_max = 0;
		if(setrlimit(RLIMIT_CORE, &rlim) < 0)
			die("%s: setrlimit: %s\n", argv[0], strerror(errno));

		#ifdef PYTHON_VERSION
		/* the -E switch has been added in version 2.2 */
		if(strcmp(PYTHON_VERSION, "2.2") >= 0) {
			/* this should be superfluous given the castrated environment */
			*(a++) = "-E";
		}
		#endif
	}

	*(a++) = fullpath;

	for(i = 1; argv[i] != NULL; i++)
		*(a++) = argv[i];

	*a = NULL;
	
	execv(python, args);

	die("%s: unable to execute %s: %s\n", argv[0], fullpath, strerror(errno));

	return 1;
}