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 <net/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_ALIGN(rt_skb->len) +
  43               NLMSG_ALIGN(sizeof(struct nf_dn_rtmsg));
  44        skb = nlmsg_new(size, GFP_ATOMIC);
  45        if (!skb) {
  46                *errp = -ENOMEM;
  47                return NULL;
  48        }
  49        old_tail = skb->tail;
  50        nlh = nlmsg_put(skb, 0, 0, 0, size, 0);
  51        if (!nlh) {
  52                kfree_skb(skb);
  53                *errp = -ENOMEM;
  54                return NULL;
  55        }
  56        rtm = (struct nf_dn_rtmsg *)nlmsg_data(nlh);
  57        rtm->nfdn_ifindex = rt_skb->dev->ifindex;
  58        ptr = NFDN_RTMSG(rtm);
  59        skb_copy_from_linear_data(rt_skb, ptr, rt_skb->len);
  60        nlh->nlmsg_len = skb->tail - old_tail;
  61        return skb;
  62}
  63
  64static void dnrmg_send_peer(struct sk_buff *skb)
  65{
  66        struct sk_buff *skb2;
  67        int status = 0;
  68        int group = 0;
  69        unsigned char flags = *skb->data;
  70
  71        switch (flags & DN_RT_CNTL_MSK) {
  72        case DN_RT_PKT_L1RT:
  73                group = DNRNG_NLGRP_L1;
  74                break;
  75        case DN_RT_PKT_L2RT:
  76                group = DNRNG_NLGRP_L2;
  77                break;
  78        default:
  79                return;
  80        }
  81
  82        skb2 = dnrmg_build_message(skb, &status);
  83        if (skb2 == NULL)
  84                return;
  85        NETLINK_CB(skb2).dst_group = group;
  86        netlink_broadcast(dnrmg, skb2, 0, group, GFP_ATOMIC);
  87}
  88
  89
  90static unsigned int dnrmg_hook(void *priv,
  91                        struct sk_buff *skb,
  92                        const struct nf_hook_state *state)
  93{
  94        dnrmg_send_peer(skb);
  95        return NF_ACCEPT;
  96}
  97
  98
  99#define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err), NULL); return; } while (0)
 100
 101static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
 102{
 103        struct nlmsghdr *nlh = nlmsg_hdr(skb);
 104
 105        if (skb->len < sizeof(*nlh) ||
 106            nlh->nlmsg_len < sizeof(*nlh) ||
 107            skb->len < nlh->nlmsg_len)
 108                return;
 109
 110        if (!netlink_capable(skb, CAP_NET_ADMIN))
 111                RCV_SKB_FAIL(-EPERM);
 112
 113        /* Eventually we might send routing messages too */
 114
 115        RCV_SKB_FAIL(-EINVAL);
 116}
 117
 118static const struct nf_hook_ops dnrmg_ops = {
 119        .hook           = dnrmg_hook,
 120        .pf             = NFPROTO_DECNET,
 121        .hooknum        = NF_DN_ROUTE,
 122        .priority       = NF_DN_PRI_DNRTMSG,
 123};
 124
 125static int __init dn_rtmsg_init(void)
 126{
 127        int rv = 0;
 128        struct netlink_kernel_cfg cfg = {
 129                .groups = DNRNG_NLGRP_MAX,
 130                .input  = dnrmg_receive_user_skb,
 131        };
 132
 133        dnrmg = netlink_kernel_create(&init_net, NETLINK_DNRTMSG, &cfg);
 134        if (dnrmg == NULL) {
 135                printk(KERN_ERR "dn_rtmsg: Cannot create netlink socket");
 136                return -ENOMEM;
 137        }
 138
 139        rv = nf_register_net_hook(&init_net, &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_net_hook(&init_net, &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