/*
 * cpuctl_group_changer.c
 *
 * Used to change the group of running tasks to the correct
 * uid container.
 *
 * Copyright IBM Corporation, 2007
 * Author: Dhaval Giani <dhaval@linux.vnet.ibm.com>
 * Derived from test_cn_proc.c by Matt Helsley
 * Original copyright notice follows
 *
 * Copyright (C) Matt Helsley, IBM Corp. 2005
 * Derived from fcctl.c by Guillaume Thouvenin
 * Original copyright notice follows:
 *
 * Copyright (C) 2005 BULL SA.
 * Written by Guillaume Thouvenin <guillaume.thouvenin@bull.net>
 *
 * This program 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.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <string.h>

#include <sys/socket.h>
#include <sys/types.h>

#include <sys/stat.h>
#include <sys/param.h>

#include <linux/connector.h>
#include <linux/netlink.h>
#include "linux/cn_proc.h"

#include <errno.h>

#include <signal.h>
#include <setjmp.h>

#define SEND_MESSAGE_LEN (NLMSG_LENGTH(sizeof(struct cn_msg) + \
				       sizeof(enum proc_cn_mcast_op)))
#define RECV_MESSAGE_LEN (NLMSG_LENGTH(sizeof(struct cn_msg) + \
				       sizeof(struct proc_event)))

#define SEND_MESSAGE_SIZE    (NLMSG_SPACE(SEND_MESSAGE_LEN))
#define RECV_MESSAGE_SIZE    (NLMSG_SPACE(RECV_MESSAGE_LEN))

#define max(x,y) ((y)<(x)?(x):(y))
#define min(x,y) ((y)>(x)?(x):(y))

#define BUFF_SIZE (max(max(SEND_MESSAGE_SIZE, RECV_MESSAGE_SIZE), 1024))
#define MIN_RECV_SIZE (min(SEND_MESSAGE_SIZE, RECV_MESSAGE_SIZE))

#define PROC_CN_MCAST_LISTEN (1)
#define PROC_CN_MCAST_IGNORE (2)

/*
 * SIGINT causes the program to exit gracefully
 * this could happen any time after the LISTEN message has
 * been sent
 */
#define INTR_SIG SIGINT


sigjmp_buf g_jmp;
char cpuctl_fs_path[MAXPATHLEN];

void handle_intr (int signum)
{
	siglongjmp(g_jmp, signum);
}

static inline void itos(int i, char* str)
{
	sprintf(str, "%d", i);
}

int set_notify_release(int val)
{
	FILE *f;

	f = fopen("notify_on_release", "r+");
	fprintf(f, "%d\n", val);
	fclose(f);
	return 0;
}

int add_task_pid(int pid)
{
	FILE *f;

	f = fopen("tasks", "a");
	fprintf(f, "%d\n", pid);
	fclose(f);
	return 0;
}

int set_value(char* file, char *str)
{
	FILE *f;

	f=fopen(file, "w");
	fprintf(f, "%s", str);
	fclose(f);
	return 0;
}

int change_group(int pid, int uid)
{
	char str[100];
	int ret;

	ret = chdir(cpuctl_fs_path);
	itos(uid, str);
	ret = mkdir(str, 0777);
	if (ret == -1) {
		/*
		 * If the folder already exists, then it is alright. anything
		 * else should be killed
		 */
		if (errno != EEXIST) {
			perror("mkdir");
			return -1;
		}
	}
	ret = chdir(str);
	if (ret == -1) {
		/*Again, i am just quitting the program!*/
		perror("chdir");
		return -1;
	}
	/*If using cpusets set cpus and mems*
	 *
	 * set_value("cpus","0");
	 * set_value("mems","0");
	 */
	set_notify_release(1);
	add_task_pid(pid);
	return 0;
}

int handle_msg (struct cn_msg *cn_hdr)
{
	struct proc_event *ev;
	int ret;

	ev = (struct proc_event*)cn_hdr->data;

	switch(ev->what){
	case PROC_EVENT_UID:
		printf("UID Change happening\n");
		printf("UID = %d\tPID=%d\n", ev->event_data.id.e.euid,
						ev->event_data.id.process_pid);
		ret = change_group(ev->event_data.id.process_pid,
					ev->event_data.id.r.ruid);
		break;
	case PROC_EVENT_FORK:
	case PROC_EVENT_EXEC:
	case PROC_EVENT_EXIT:
	default:
		break;
	}
	return ret;
}
int main(int argc, char **argv)
{
	int sk_nl;
	int err;
	struct sockaddr_nl my_nla, kern_nla, from_nla;
	socklen_t from_nla_len;
	char buff[BUFF_SIZE];
	int rc = -1;
	struct nlmsghdr *nl_hdr;
	struct cn_msg *cn_hdr;
	enum proc_cn_mcast_op *mcop_msg;
	size_t recv_len = 0;
	FILE *f;

	if (argc == 1)
		strcpy(cpuctl_fs_path, "/dev/cpuctl");
	else
		strcpy(cpuctl_fs_path, argv[1]);
	chdir(cpuctl_fs_path);
	f = fopen("tasks", "r");
	if (f == NULL) {
		printf("Container not mounted at %s\n", cpuctl_fs_path);
		return -1;
	}
	fclose(f);
	f = fopen("notify_on_release", "r");
	if (f == NULL) {
		printf("Container not mounted at %s\n", cpuctl_fs_path);
		return -1;
	}
	fclose(f);
	if (getuid() != 0) {
		printf("Only root can start/stop the fork connector\n");
		return 0;
	}
	/*
	 * Create an endpoint for communication. Use the kernel user
	 * interface device (PF_NETLINK) which is a datagram oriented
	 * service (SOCK_DGRAM). The protocol used is the connector
	 * protocol (NETLINK_CONNECTOR)
	 */
	sk_nl = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_CONNECTOR);
	if (sk_nl == -1) {
		printf("socket sk_nl error");
		return rc;
	}
	my_nla.nl_family = AF_NETLINK;
	my_nla.nl_groups = CN_IDX_PROC;
	my_nla.nl_pid = getpid();

	kern_nla.nl_family = AF_NETLINK;
	kern_nla.nl_groups = CN_IDX_PROC;
	kern_nla.nl_pid = 1;

	err = bind(sk_nl, (struct sockaddr *)&my_nla, sizeof(my_nla));
	if (err == -1) {
		printf("binding sk_nl error");
		goto close_and_exit;
	}
	nl_hdr = (struct nlmsghdr *)buff;
	cn_hdr = (struct cn_msg *)NLMSG_DATA(nl_hdr);
	mcop_msg = (enum proc_cn_mcast_op*)&cn_hdr->data[0];
	printf("sending proc connector: PROC_CN_MCAST_LISTEN... ");
	memset(buff, 0, sizeof(buff));
	*mcop_msg = PROC_CN_MCAST_LISTEN;
	signal(INTR_SIG, handle_intr);
	/* fill the netlink header */
	nl_hdr->nlmsg_len = SEND_MESSAGE_LEN;
	nl_hdr->nlmsg_type = NLMSG_DONE;
	nl_hdr->nlmsg_flags = 0;
	nl_hdr->nlmsg_seq = 0;
	nl_hdr->nlmsg_pid = getpid();
	/* fill the connector header */
	cn_hdr->id.idx = CN_IDX_PROC;
	cn_hdr->id.val = CN_VAL_PROC;
	cn_hdr->seq = 0;
	cn_hdr->ack = 0;
	cn_hdr->len = sizeof(enum proc_cn_mcast_op);
	if (send(sk_nl, nl_hdr, nl_hdr->nlmsg_len, 0) != nl_hdr->nlmsg_len) {
		printf("failed to send proc connector mcast ctl op!\n");
		goto close_and_exit;
	}
	printf("sent\n");
	for(memset(buff, 0, sizeof(buff)), from_nla_len = sizeof(from_nla);
	  ; memset(buff, 0, sizeof(buff)), from_nla_len = sizeof(from_nla)) {
		struct nlmsghdr *nlh = (struct nlmsghdr*)buff;
		memcpy(&from_nla, &kern_nla, sizeof(from_nla));
		recv_len = recvfrom(sk_nl, buff, BUFF_SIZE, 0,
				(struct sockaddr*)&from_nla, &from_nla_len);
		if (recv_len < 1)
			continue;
		while (NLMSG_OK(nlh, recv_len)) {
			cn_hdr = NLMSG_DATA(nlh);
			if (nlh->nlmsg_type == NLMSG_NOOP)
				continue;
			if ((nlh->nlmsg_type == NLMSG_ERROR) ||
			    (nlh->nlmsg_type == NLMSG_OVERRUN))
				break;
			if(handle_msg(cn_hdr)<0) {
				goto close_and_exit;
			}
			if (nlh->nlmsg_type == NLMSG_DONE)
				break;
			nlh = NLMSG_NEXT(nlh, recv_len);
		}
	}
close_and_exit:
	close(sk_nl);
	exit(rc);

	return 0;
}