net/decnet/netfilter/dn_rtmsg.c

   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
  29 #include <linux/netfilter_decnet.h>
  30
  31 static struct sock *dnrmg = NULL;
  32
  33
  34 static struct sk_buff *dnrmg_build_message(struct sk_buff *rt_skb, int *errp)
  35 {
  36         struct sk_buff *skb = NULL;
  37         size_t size;
  38         unsigned char *old_tail;
  39         struct nlmsghdr *nlh;
  40         unsigned char *ptr;
  41         struct nf_dn_rtmsg *rtm;
  42
  43         size = NLMSG_SPACE(rt_skb->len);
  44         size += NLMSG_ALIGN(sizeof(struct nf_dn_rtmsg));
  45         skb = alloc_skb(size, GFP_ATOMIC);
  46         if (!skb)
  47                 goto nlmsg_failure;
  48         old_tail = skb->tail;
  49         nlh = NLMSG_PUT(skb, 0, 0, 0, size - sizeof(*nlh));
  50         rtm = (struct nf_dn_rtmsg *)NLMSG_DATA(nlh);
  51         rtm->nfdn_ifindex = rt_skb->dev->ifindex;
  52         ptr = NFDN_RTMSG(rtm);
  53         memcpy(ptr, rt_skb->data, rt_skb->len);
  54         nlh->nlmsg_len = skb->tail - old_tail;
  55         return skb;
  56
  57 nlmsg_failure:
  58         if (skb)
  59                 kfree_skb(skb);
  60         *errp = -ENOMEM;
  61         if (net_ratelimit())
  62                 printk(KERN_ERR "dn_rtmsg: error creating netlink message\n");
  63         return NULL;
  64 }
  65
  66 static void dnrmg_send_peer(struct sk_buff *skb)
  67 {
  68         struct sk_buff *skb2;
  69         int status = 0;
  70         int group = 0;
  71         unsigned char flags = *skb->data;
  72
  73         switch(flags & DN_RT_CNTL_MSK) {
  74                 case DN_RT_PKT_L1RT:
  75                         group = DNRNG_NLGRP_L1;
  76                         break;
  77                 case DN_RT_PKT_L2RT:
  78                         group = DNRNG_NLGRP_L2;
  79                         break;
  80                 default:
  81                         return;
  82         }
  83
  84         skb2 = dnrmg_build_message(skb, &status);
  85         if (skb2 == NULL)
  86                 return;
  87         NETLINK_CB(skb2).dst_group = group;
  88         netlink_broadcast(dnrmg, skb2, 0, group, GFP_ATOMIC);
  89 }
  90
  91
  92 static unsigned int dnrmg_hook(unsigned int hook,
  93                         struct sk_buff **pskb,
  94                         const struct net_device *in,
  95                         const struct net_device *out,
  96                         int (*okfn)(struct sk_buff *))
  97 {
  98         dnrmg_send_peer(*pskb);
  99         return NF_ACCEPT;
 100 }
 101
 102
 103 #define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
 104
 105 static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
 106 {
 107         struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data;
 108
 109         if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
 110                 return;
 111
 112         if (!cap_raised(NETLINK_CB(skb).eff_cap, CAP_NET_ADMIN))
 113                 RCV_SKB_FAIL(-EPERM);
 114
 115         /* Eventually we might send routing messages too */
 116
 117         RCV_SKB_FAIL(-EINVAL);
 118 }
 119
 120 static void dnrmg_receive_user_sk(struct sock *sk, int len)
 121 {
 122         struct sk_buff *skb;
 123         unsigned int qlen = skb_queue_len(&sk->sk_receive_queue);
 124
 125         for (; qlen && (skb = skb_dequeue(&sk->sk_receive_queue)); qlen--) {
 126                 dnrmg_receive_user_skb(skb);
 127                 kfree_skb(skb);
 128         }
 129 }
 130
 131 static struct nf_hook_ops dnrmg_ops = {
 132         .hook           = dnrmg_hook,
 133         .pf             = PF_DECnet,
 134         .hooknum        = NF_DN_ROUTE,
 135         .priority       = NF_DN_PRI_DNRTMSG,
 136 };
 137
 138 static int __init init(void)
 139 {
 140         int rv = 0;
 141
 142         dnrmg = netlink_kernel_create(NETLINK_DNRTMSG, DNRNG_NLGRP_MAX,
 143                                       dnrmg_receive_user_sk, THIS_MODULE);
 144         if (dnrmg == NULL) {
 145                 printk(KERN_ERR "dn_rtmsg: Cannot create netlink socket");
 146                 return -ENOMEM;
 147         }
 148
 149         rv = nf_register_hook(&dnrmg_ops);
 150         if (rv) {
 151                 sock_release(dnrmg->sk_socket);
 152         }
 153
 154         return rv;
 155 }
 156
 157 static void __exit fini(void)
 158 {
 159         nf_unregister_hook(&dnrmg_ops);
 160         sock_release(dnrmg->sk_socket);
 161 }
 162
 163
 164 MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
 165 MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
 166 MODULE_LICENSE("GPL");
 167 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_DNRTMSG);
 168
 169 module_init(init);
 170 module_exit(fini);
 171