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/init.h>
  18#include <linux/netdevice.h>
  19#include <linux/netfilter.h>
  20#include <linux/spinlock.h>
  21#include <linux/netlink.h>
  22#include <linux/netfilter_decnet.h>
  23
  24#include <net/sock.h>
  25#include <net/flow.h>
  26#include <net/dn.h>
  27#include <net/dn_route.h>
  28
  29static struct sock *dnrmg = NULL;
  30
  31
  32static struct sk_buff *dnrmg_build_message(struct sk_buff *rt_skb, int *errp)
  33{
  34        struct sk_buff *skb = NULL;
  35        size_t size;
  36        sk_buff_data_t old_tail;
  37        struct nlmsghdr *nlh;
  38        unsigned char *ptr;
  39        struct nf_dn_rtmsg *rtm;
  40
  41        size = NLMSG_SPACE(rt_skb->len);
  42        size += NLMSG_ALIGN(sizeof(struct nf_dn_rtmsg));
  43        skb = alloc_skb(size, GFP_ATOMIC);
  44        if (!skb)
  45                goto nlmsg_failure;
  46        old_tail = skb->tail;
  47        nlh = NLMSG_PUT(skb, 0, 0, 0, size - sizeof(*nlh));
  48        rtm = (struct nf_dn_rtmsg *)NLMSG_DATA(nlh);
  49        rtm->nfdn_ifindex = rt_skb->dev->ifindex;
  50        ptr = NFDN_RTMSG(rtm);
  51        skb_copy_from_linear_data(rt_skb, ptr, rt_skb->len);
  52        nlh->nlmsg_len = skb->tail - old_tail;
  53        return skb;
  54
  55nlmsg_failure:
  56        if (skb)
  57                kfree_skb(skb);
  58        *errp = -ENOMEM;
  59        if (net_ratelimit())
  60                printk(KERN_ERR "dn_rtmsg: error creating netlink message\n");
  61        return NULL;
  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(unsigned int hook,
  91                        struct sk_buff *skb,
  92                        const struct net_device *in,
  93                        const struct net_device *out,
  94                        int (*okfn)(struct sk_buff *))
  95{
  96        dnrmg_send_peer(skb);
  97        return NF_ACCEPT;
  98}
  99
 100
 101#define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
 102
 103static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
 104{
 105        struct nlmsghdr *nlh = nlmsg_hdr(skb);
 106
 107        if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
 108                return;
 109
 110        if (security_netlink_recv(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 struct nf_hook_ops dnrmg_ops __read_mostly = {
 119        .hook           = dnrmg_hook,
 120        .pf             = PF_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
 129        dnrmg = netlink_kernel_create(&init_net,
 130                                      NETLINK_DNRTMSG, DNRNG_NLGRP_MAX,
 131                                      dnrmg_receive_user_skb,
 132                                      NULL, THIS_MODULE);
 133        if (dnrmg == NULL) {
 134                printk(KERN_ERR "dn_rtmsg: Cannot create netlink socket");
 135                return -ENOMEM;
 136        }
 137
 138        rv = nf_register_hook(&dnrmg_ops);
 139        if (rv) {
 140                netlink_kernel_release(dnrmg);
 141        }
 142
 143        return rv;
 144}
 145
 146static void __exit dn_rtmsg_fini(void)
 147{
 148        nf_unregister_hook(&dnrmg_ops);
 149        netlink_kernel_release(dnrmg);
 150}
 151
 152
 153MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
 154MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
 155MODULE_LICENSE("GPL");
 156MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_DNRTMSG);
 157
 158module_init(dn_rtmsg_init);
 159module_exit(dn_rtmsg_fini);
 160
 161