ip_queue.c

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	}
	if (!skb_ip_make_writable(&e->skb, v->data_len))
		return -ENOMEM;
	memcpy(e->skb->data, v->payload, v->data_len);
	e->skb->nfcache |= NFC_ALTERED;

	/*
	 * Extra routing may needed on local out, as the QUEUE target never
	 * returns control to the table.
	 */
	if (e->info->hook == NF_IP_LOCAL_OUT) {
		struct iphdr *iph = e->skb->nh.iph;

		if (!(iph->tos == e->rt_info.tos
		      && iph->daddr == e->rt_info.daddr
		      && iph->saddr == e->rt_info.saddr))
			return ip_route_me_harder(&e->skb);
	}
	return 0;
}

static inline int
id_cmp(struct ipq_queue_entry *e, unsigned long id)
{
	return (id == (unsigned long )e);
}

static int
ipq_set_verdict(struct ipq_verdict_msg *vmsg, unsigned int len)
{
	struct ipq_queue_entry *entry;

	if (vmsg->value > NF_MAX_VERDICT)
		return -EINVAL;

	entry = ipq_find_dequeue_entry(id_cmp, vmsg->id);
	if (entry == NULL)
		return -ENOENT;
	else {
		int verdict = vmsg->value;
		
		if (vmsg->data_len && vmsg->data_len == len)
			if (ipq_mangle_ipv4(vmsg, entry) < 0)
				verdict = NF_DROP;
		
		ipq_issue_verdict(entry, verdict);
		return 0;
	}
}

static int
ipq_set_mode(unsigned char mode, unsigned int range)
{
	int status;

	write_lock_bh(&queue_lock);
	status = __ipq_set_mode(mode, range);
	write_unlock_bh(&queue_lock);
	return status;
}

static int
ipq_receive_peer(struct ipq_peer_msg *pmsg,
                 unsigned char type, unsigned int len)
{
	int status = 0;

	if (len < sizeof(*pmsg))
		return -EINVAL;

	switch (type) {
	case IPQM_MODE:
		status = ipq_set_mode(pmsg->msg.mode.value,
		                      pmsg->msg.mode.range);
		break;
		
	case IPQM_VERDICT:
		if (pmsg->msg.verdict.value > NF_MAX_VERDICT)
			status = -EINVAL;
		else
			status = ipq_set_verdict(&pmsg->msg.verdict,
			                         len - sizeof(*pmsg));
			break;
	default:
		status = -EINVAL;
	}
	return status;
}

static int
dev_cmp(struct ipq_queue_entry *entry, unsigned long ifindex)
{
	if (entry->info->indev)
		if (entry->info->indev->ifindex == ifindex)
			return 1;
			
	if (entry->info->outdev)
		if (entry->info->outdev->ifindex == ifindex)
			return 1;

	return 0;
}

static void
ipq_dev_drop(int ifindex)
{
	struct ipq_queue_entry *entry;
	
	while ((entry = ipq_find_dequeue_entry(dev_cmp, ifindex)) != NULL)
		ipq_issue_verdict(entry, NF_DROP);
}

#define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)

static inline void
ipq_rcv_skb(struct sk_buff *skb)
{
	int status, type, pid, flags, nlmsglen, skblen;
	struct nlmsghdr *nlh;

	skblen = skb->len;
	if (skblen < sizeof(*nlh))
		return;

	nlh = (struct nlmsghdr *)skb->data;
	nlmsglen = nlh->nlmsg_len;
	if (nlmsglen < sizeof(*nlh) || skblen < nlmsglen)
		return;

	pid = nlh->nlmsg_pid;
	flags = nlh->nlmsg_flags;
	
	if(pid <= 0 || !(flags & NLM_F_REQUEST) || flags & NLM_F_MULTI)
		RCV_SKB_FAIL(-EINVAL);
		
	if (flags & MSG_TRUNC)
		RCV_SKB_FAIL(-ECOMM);
		
	type = nlh->nlmsg_type;
	if (type < NLMSG_NOOP || type >= IPQM_MAX)
		RCV_SKB_FAIL(-EINVAL);
		
	if (type <= IPQM_BASE)
		return;
		
	if (security_netlink_recv(skb))
		RCV_SKB_FAIL(-EPERM);
	
	write_lock_bh(&queue_lock);
	
	if (peer_pid) {
		if (peer_pid != pid) {
			write_unlock_bh(&queue_lock);
			RCV_SKB_FAIL(-EBUSY);
		}
	} else {
		net_enable_timestamp();
		peer_pid = pid;
	}
		
	write_unlock_bh(&queue_lock);
	
	status = ipq_receive_peer(NLMSG_DATA(nlh), type,
	                          skblen - NLMSG_LENGTH(0));
	if (status < 0)
		RCV_SKB_FAIL(status);
		
	if (flags & NLM_F_ACK)
		netlink_ack(skb, nlh, 0);
        return;
}

static void
ipq_rcv_sk(struct sock *sk, int len)
{
	do {
		struct sk_buff *skb;

		if (down_trylock(&ipqnl_sem))
			return;
			
		while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
			ipq_rcv_skb(skb);
			kfree_skb(skb);
		}
		
		up(&ipqnl_sem);

	} while (ipqnl && ipqnl->sk_receive_queue.qlen);
}

static int
ipq_rcv_dev_event(struct notifier_block *this,
                  unsigned long event, void *ptr)
{
	struct net_device *dev = ptr;

	/* Drop any packets associated with the downed device */
	if (event == NETDEV_DOWN)
		ipq_dev_drop(dev->ifindex);
	return NOTIFY_DONE;
}

static struct notifier_block ipq_dev_notifier = {
	.notifier_call	= ipq_rcv_dev_event,
};

static int
ipq_rcv_nl_event(struct notifier_block *this,
                 unsigned long event, void *ptr)
{
	struct netlink_notify *n = ptr;

	if (event == NETLINK_URELEASE &&
	    n->protocol == NETLINK_FIREWALL && n->pid) {
		write_lock_bh(&queue_lock);
		if (n->pid == peer_pid)
			__ipq_reset();
		write_unlock_bh(&queue_lock);
	}
	return NOTIFY_DONE;
}

static struct notifier_block ipq_nl_notifier = {
	.notifier_call	= ipq_rcv_nl_event,
};

static struct ctl_table_header *ipq_sysctl_header;

static ctl_table ipq_table[] = {
	{
		.ctl_name	= NET_IPQ_QMAX,
		.procname	= NET_IPQ_QMAX_NAME,
		.data		= &queue_maxlen,
		.maxlen		= sizeof(queue_maxlen),
		.mode		= 0644,
		.proc_handler	= proc_dointvec
	},
 	{ .ctl_name = 0 }
};

static ctl_table ipq_dir_table[] = {
	{
		.ctl_name	= NET_IPV4,
		.procname	= "ipv4",
		.mode		= 0555,
		.child		= ipq_table
	},
	{ .ctl_name = 0 }
};

static ctl_table ipq_root_table[] = {
	{
		.ctl_name	= CTL_NET,
		.procname	= "net",
		.mode		= 0555,
		.child		= ipq_dir_table
	},
	{ .ctl_name = 0 }
};

#ifdef CONFIG_PROC_FS
static int
ipq_get_info(char *buffer, char **start, off_t offset, int length)
{
	int len;

	read_lock_bh(&queue_lock);
	
	len = sprintf(buffer,
	              "Peer PID          : %d\n"
	              "Copy mode         : %hu\n"
	              "Copy range        : %u\n"
	              "Queue length      : %u\n"
	              "Queue max. length : %u\n",
	              peer_pid,
	              copy_mode,
	              copy_range,
	              queue_total,
	              queue_maxlen);

	read_unlock_bh(&queue_lock);
	
	*start = buffer + offset;
	len -= offset;
	if (len > length)
		len = length;
	else if (len < 0)
		len = 0;
	return len;
}
#endif /* CONFIG_PROC_FS */

static int
init_or_cleanup(int init)
{
	int status = -ENOMEM;
	struct proc_dir_entry *proc;
	
	if (!init)
		goto cleanup;

	netlink_register_notifier(&ipq_nl_notifier);
	ipqnl = netlink_kernel_create(NETLINK_FIREWALL, ipq_rcv_sk);
	if (ipqnl == NULL) {
		printk(KERN_ERR "ip_queue: failed to create netlink socket\n");
		goto cleanup_netlink_notifier;
	}

	proc = proc_net_create(IPQ_PROC_FS_NAME, 0, ipq_get_info);
	if (proc)
		proc->owner = THIS_MODULE;
	else {
		printk(KERN_ERR "ip_queue: failed to create proc entry\n");
		goto cleanup_ipqnl;
	}
	
	register_netdevice_notifier(&ipq_dev_notifier);
	ipq_sysctl_header = register_sysctl_table(ipq_root_table, 0);
	
	status = nf_register_queue_handler(PF_INET, ipq_enqueue_packet, NULL);
	if (status < 0) {
		printk(KERN_ERR "ip_queue: failed to register queue handler\n");
		goto cleanup_sysctl;
	}
	return status;

cleanup:
	nf_unregister_queue_handler(PF_INET);
	synchronize_net();
	ipq_flush(NF_DROP);
	
cleanup_sysctl:
	unregister_sysctl_table(ipq_sysctl_header);
	unregister_netdevice_notifier(&ipq_dev_notifier);
	proc_net_remove(IPQ_PROC_FS_NAME);
	
cleanup_ipqnl:
	sock_release(ipqnl->sk_socket);
	down(&ipqnl_sem);
	up(&ipqnl_sem);
	
cleanup_netlink_notifier:
	netlink_unregister_notifier(&ipq_nl_notifier);
	return status;
}

static int __init init(void)
{
	
	return init_or_cleanup(1);
}

static void __exit fini(void)
{
	init_or_cleanup(0);
}

MODULE_DESCRIPTION("IPv4 packet queue handler");
MODULE_AUTHOR("James Morris <[e-mail]>");
MODULE_LICENSE("GPL");

module_init(init);
module_exit(fini);