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/*
* gcsd
*
* gcsd the generic command sequencer daemon can be used to serialize
* commands sent over various paralell communication channels to a
* single command output. It can be seen as a multiplexer for any
* kind of communication between a single resource and various clients
* which want to submit commands to it or query information from it.
* gcsd is written in C and Lua. The goal is to provide an easy to
* understand high level API based on Lua which can be used to
* implement the business logic of the so formed multiplexer daemon.
*
*
* Copyright (C) 2009-2010 Markus Grueneis <gimpf@spreadspace.org>
* Christian Pointner <equinox@spreadspace.org>
*
* This file is part of gcsd.
*
* gcsd 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 3 of the License, or
* any later version.
*
* gcsd 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 gcsd. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef GCSD_daemon_h_INCLUDED
#define GCSD_daemon_h_INCLUDED
#include <poll.h>
#include <fcntl.h>
#include <pwd.h>
#include <grp.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
struct priv_info_struct {
struct passwd* pw_;
struct group* gr_;
};
typedef struct priv_info_struct priv_info_t;
int priv_init(priv_info_t* priv, const char* username, const char* groupname)
{
if(!priv)
return -1;
priv->pw_ = NULL;
priv->gr_ = NULL;
priv->pw_ = getpwnam(username);
if(!priv->pw_) {
log_printf(ERROR, "unkown user %s", username);
return -1;
}
if(groupname)
priv->gr_ = getgrnam(groupname);
else
priv->gr_ = getgrgid(priv->pw_->pw_gid);
if(!priv->gr_) {
log_printf(ERROR, "unkown group %s", groupname);
return -1;
}
return 0;
}
int priv_drop(priv_info_t* priv)
{
if(!priv || !priv->pw_ || !priv->gr_) {
log_printf(ERROR, "privileges not initialized properly");
return -1;
}
if(setgid(priv->gr_->gr_gid)) {
log_printf(ERROR, "setgid('%s') failed: %s", priv->gr_->gr_name, strerror(errno));
return -1;
}
gid_t gr_list[1];
gr_list[0] = priv->gr_->gr_gid;
if(setgroups (1, gr_list)) {
log_printf(ERROR, "setgroups(['%s']) failed: %s", priv->gr_->gr_name, strerror(errno));
return -1;
}
if(setuid(priv->pw_->pw_uid)) {
log_printf(ERROR, "setuid('%s') failed: %s", priv->pw_->pw_name, strerror(errno));
return -1;
}
log_printf(NOTICE, "dropped privileges to %s:%s", priv->pw_->pw_name, priv->gr_->gr_name);
return 0;
}
int do_chroot(const char* chrootdir)
{
if(getuid() != 0) {
log_printf(ERROR, "this program has to be run as root in order to run in a chroot");
return -1;
}
if(chroot(chrootdir)) {
log_printf(ERROR, "can't chroot to %s: %s", chrootdir, strerror(errno));
return -1;
}
log_printf(NOTICE, "we are in chroot jail (%s) now", chrootdir);
if(chdir("/")) {
log_printf(ERROR, "can't change to /: %s", strerror(errno));
return -1;
}
return 0;
}
void daemonize()
{
pid_t pid;
pid = fork();
if(pid < 0) {
log_printf(ERROR, "daemonizing failed at fork(): %s, exitting", strerror(errno));
exit(-1);
}
if(pid) exit(0);
umask(0);
if(setsid() < 0) {
log_printf(ERROR, "daemonizing failed at setsid(): %s, exitting", strerror(errno));
exit(-1);
}
pid = fork();
if(pid < 0) {
log_printf(ERROR, "daemonizing failed at fork(): %s, exitting", strerror(errno));
exit(-1);
}
if(pid) exit(0);
if ((chdir("/")) < 0) {
log_printf(ERROR, "daemonizing failed at chdir(): %s, exitting", strerror(errno));
exit(-1);
}
int fd;
for (fd=0;fd<=2;fd++) // close all file descriptors
close(fd);
fd = open("/dev/null",O_RDWR); // stdin
if(fd == -1)
log_printf(WARNING, "can't open stdin (chroot and no link to /dev/null?)");
else {
if(dup(fd) == -1) // stdout
log_printf(WARNING, "can't open stdout");
if(dup(fd) == -1) // stderr
log_printf(WARNING, "can't open stderr");
}
umask(027);
}
#endif
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