LXR linux/net/decnet/netfilter/dn

   1/*
   2 * DECnet       An implementation of the DECnet protocol suite for the LINUX
   3 *              operating system.  DECnet is implemented using the  BSD Socket
   4 *              interface as the means of communication with the user level.
   5 *
   6 *              DECnet Routing Message Grabulator
   7 *
   8 *              (C) 2000 ChyGwyn Limited  -  http://www.chygwyn.com/
   9 *              This code may be copied under the GPL v.2 or at your option
  10 *              any later version.
  11 *
  12 * Author:      Steven Whitehouse <steve@chygwyn.com>
  13 *
  14 */
  15#include <linux/module.h>
  16#include <linux/skbuff.h>
  17#include <linux/slab.h>
  18#include <linux/init.h>
  19#include <linux/netdevice.h>
  20#include <linux/netfilter.h>
  21#include <linux/spinlock.h>
  22#include <linux/netlink.h>
  23#include <linux/netfilter_decnet.h>
  24
  25#include <net/sock.h>
  26#include <net/flow.h>
  27#include <net/dn.h>
  28#include <net/dn_route.h>
  29
  30static struct sock *dnrmg = NULL;
  31
  32
  33static struct sk_buff *dnrmg_build_message(struct sk_buff *rt_skb, int *errp)
  34{
  35        struct sk_buff *skb = NULL;
  36        size_t size;
  37        sk_buff_data_t old_tail;
  38        struct nlmsghdr *nlh;
  39        unsigned char *ptr;
  40        struct nf_dn_rtmsg *rtm;
  41
  42        size = NLMSG_SPACE(rt_skb->len);
  43        size += NLMSG_ALIGN(sizeof(struct nf_dn_rtmsg));
  44        skb = alloc_skb(size, GFP_ATOMIC);
  45        if (!skb)
  46                goto nlmsg_failure;
  47        old_tail = skb->tail;
  48        nlh = NLMSG_PUT(skb, 0, 0, 0, size - sizeof(*nlh));
  49        rtm = (struct nf_dn_rtmsg *)NLMSG_DATA(nlh);
  50        rtm->nfdn_ifindex = rt_skb->dev->ifindex;
  51        ptr = NFDN_RTMSG(rtm);
  52        skb_copy_from_linear_data(rt_skb, ptr, rt_skb->len);
  53        nlh->nlmsg_len = skb->tail - old_tail;
  54        return skb;
  55
  56nlmsg_failure:
  57        if (skb)
  58                kfree_skb(skb);
  59        *errp = -ENOMEM;
  60        if (net_ratelimit())
  61                printk(KERN_ERR "dn_rtmsg: error creating netlink message\n");
  62        return NULL;
  63}
  64
  65static void dnrmg_send_peer(struct sk_buff *skb)
  66{
  67        struct sk_buff *skb2;
  68        int status = 0;
  69        int group = 0;
  70        unsigned char flags = *skb->data;
  71
  72        switch(flags & DN_RT_CNTL_MSK) {
  73                case DN_RT_PKT_L1RT:
  74                        group = DNRNG_NLGRP_L1;
  75                        break;
  76                case DN_RT_PKT_L2RT:
  77                        group = DNRNG_NLGRP_L2;
  78                        break;
  79                default:
  80                        return;
  81        }
  82
  83        skb2 = dnrmg_build_message(skb, &status);
  84        if (skb2 == NULL)
  85                return;
  86        NETLINK_CB(skb2).dst_group = group;
  87        netlink_broadcast(dnrmg, skb2, 0, group, GFP_ATOMIC);
  88}
  89
  90
  91static unsigned int dnrmg_hook(unsigned int hook,
  92                        struct sk_buff *skb,
  93                        const struct net_device *in,
  94                        const struct net_device *out,
  95                        int (*okfn)(struct sk_buff *))
  96{
  97        dnrmg_send_peer(skb);
  98        return NF_ACCEPT;
  99}
 100
 101
 102#define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
 103
 104static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
 105{
 106        struct nlmsghdr *nlh = nlmsg_hdr(skb);
 107
 108        if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
 109                return;
 110
 111        if (security_netlink_recv(skb, CAP_NET_ADMIN))
 112                RCV_SKB_FAIL(-EPERM);
 113
 114        /* Eventually we might send routing messages too */
 115
 116        RCV_SKB_FAIL(-EINVAL);
 117}
 118
 119static struct nf_hook_ops dnrmg_ops __read_mostly = {
 120        .hook           = dnrmg_hook,
 121        .pf             = PF_DECnet,
 122        .hooknum        = NF_DN_ROUTE,
 123        .priority       = NF_DN_PRI_DNRTMSG,
 124};
 125
 126static int __init dn_rtmsg_init(void)
 127{
 128        int rv = 0;
 129
 130        dnrmg = netlink_kernel_create(&init_net,
 131                                      NETLINK_DNRTMSG, DNRNG_NLGRP_MAX,
 132                                      dnrmg_receive_user_skb,
 133                                      NULL, THIS_MODULE);
 134        if (dnrmg == NULL) {
 135                printk(KERN_ERR "dn_rtmsg: Cannot create netlink socket");
 136                return -ENOMEM;
 137        }
 138
 139        rv = nf_register_hook(&dnrmg_ops);
 140        if (rv) {
 141                netlink_kernel_release(dnrmg);
 142        }
 143
 144        return rv;
 145}
 146
 147static void __exit dn_rtmsg_fini(void)
 148{
 149        nf_unregister_hook(&dnrmg_ops);
 150        netlink_kernel_release(dnrmg);
 151}
 152
 153
 154MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
 155MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
 156MODULE_LICENSE("GPL");
 157MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_DNRTMSG);
 158
 159module_init(dn_rtmsg_init);
 160module_exit(dn_rtmsg_fini);
 161
 162