root/net/decnet/netfilter/dn_rtmsg.c

DEFINITIONS

1. dnrmg_build_message
2. dnrmg_send_peer
3. dnrmg_hook
4. dnrmg_receive_user_skb
5. dn_rtmsg_init
6. dn_rtmsg_fini

/*
 * DECnet       An implementation of the DECnet protocol suite for the LINUX
 *              operating system.  DECnet is implemented using the  BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              DECnet Routing Message Grabulator
 *
 *              (C) 2000 ChyGwyn Limited  -  http://www.chygwyn.com/
 *              This code may be copied under the GPL v.2 or at your option
 *              any later version.
 *
 * Author:      Steven Whitehouse <steve@chygwyn.com>
 *
 */
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/netfilter.h>
#include <linux/spinlock.h>
#include <linux/netlink.h>
#include <linux/netfilter_decnet.h>

#include <net/sock.h>
#include <net/flow.h>
#include <net/dn.h>
#include <net/dn_route.h>

static struct sock *dnrmg = NULL;


static struct sk_buff *dnrmg_build_message(struct sk_buff *rt_skb, int *errp)
{
        struct sk_buff *skb = NULL;
        size_t size;
        sk_buff_data_t old_tail;
        struct nlmsghdr *nlh;
        unsigned char *ptr;
        struct nf_dn_rtmsg *rtm;

        size = NLMSG_SPACE(rt_skb->len);
        size += NLMSG_ALIGN(sizeof(struct nf_dn_rtmsg));
        skb = alloc_skb(size, GFP_ATOMIC);
        if (!skb)
                goto nlmsg_failure;
        old_tail = skb->tail;
        nlh = NLMSG_PUT(skb, 0, 0, 0, size - sizeof(*nlh));
        rtm = (struct nf_dn_rtmsg *)NLMSG_DATA(nlh);
        rtm->nfdn_ifindex = rt_skb->dev->ifindex;
        ptr = NFDN_RTMSG(rtm);
        skb_copy_from_linear_data(rt_skb, ptr, rt_skb->len);
        nlh->nlmsg_len = skb->tail - old_tail;
        return skb;

nlmsg_failure:
        if (skb)
                kfree_skb(skb);
        *errp = -ENOMEM;
        if (net_ratelimit())
                printk(KERN_ERR "dn_rtmsg: error creating netlink message\n");
        return NULL;
}

static void dnrmg_send_peer(struct sk_buff *skb)
{
        struct sk_buff *skb2;
        int status = 0;
        int group = 0;
        unsigned char flags = *skb->data;

        switch(flags & DN_RT_CNTL_MSK) {
                case DN_RT_PKT_L1RT:
                        group = DNRNG_NLGRP_L1;
                        break;
                case DN_RT_PKT_L2RT:
                        group = DNRNG_NLGRP_L2;
                        break;
                default:
                        return;
        }

        skb2 = dnrmg_build_message(skb, &status);
        if (skb2 == NULL)
                return;
        NETLINK_CB(skb2).dst_group = group;
        netlink_broadcast(dnrmg, skb2, 0, group, GFP_ATOMIC);
}


static unsigned int dnrmg_hook(unsigned int hook,
                        struct sk_buff *skb,
                        const struct net_device *in,
                        const struct net_device *out,
                        int (*okfn)(struct sk_buff *))
{
        dnrmg_send_peer(skb);
        return NF_ACCEPT;
}


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

static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
{
        struct nlmsghdr *nlh = nlmsg_hdr(skb);

        if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
                return;

        if (security_netlink_recv(skb, CAP_NET_ADMIN))
                RCV_SKB_FAIL(-EPERM);

        /* Eventually we might send routing messages too */

        RCV_SKB_FAIL(-EINVAL);
}

static struct nf_hook_ops dnrmg_ops __read_mostly = {
        .hook           = dnrmg_hook,
        .pf             = PF_DECnet,
        .hooknum        = NF_DN_ROUTE,
        .priority       = NF_DN_PRI_DNRTMSG,
};

static int __init dn_rtmsg_init(void)
{
        int rv = 0;

        dnrmg = netlink_kernel_create(&init_net,
                                      NETLINK_DNRTMSG, DNRNG_NLGRP_MAX,
                                      dnrmg_receive_user_skb,
                                      NULL, THIS_MODULE);
        if (dnrmg == NULL) {
                printk(KERN_ERR "dn_rtmsg: Cannot create netlink socket");
                return -ENOMEM;
        }

        rv = nf_register_hook(&dnrmg_ops);
        if (rv) {
                netlink_kernel_release(dnrmg);
        }

        return rv;
}

static void __exit dn_rtmsg_fini(void)
{
        nf_unregister_hook(&dnrmg_ops);
        netlink_kernel_release(dnrmg);
}


MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_DNRTMSG);

module_init(dn_rtmsg_init);
module_exit(dn_rtmsg_fini);