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
  23 #include <net/sock.h>
  24 #include <net/flow.h>
  25 #include <net/dn.h>
  26 #include <net/dn_route.h>
  27
  28 #include <linux/netfilter_decnet.h>
  29
  30 static struct sock *dnrmg = NULL;
  31
  32
  33 static 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         unsigned char *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         memcpy(ptr, rt_skb->data, rt_skb->len);
  53         nlh->nlmsg_len = skb->tail - old_tail;
  54         return skb;
  55
  56 nlmsg_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
  65 static 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 = DNRMG_L1_GROUP;
  75                         break;
  76                 case DN_RT_PKT_L2RT:
  77                         group = DNRMG_L2_GROUP;
  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_groups = group;
  87         netlink_broadcast(dnrmg, skb2, 0, group, GFP_ATOMIC);
  88 }
  89
  90
  91 static unsigned int dnrmg_hook(unsigned int hook,
  92                         struct sk_buff **pskb,
  93                         const struct net_device *in,
  94                         const struct net_device *out,
  95                         int (*okfn)(struct sk_buff *))
  96 {
  97         dnrmg_send_peer(*pskb);
  98         return NF_ACCEPT;
  99 }
 100
 101
 102 #define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
 103
 104 static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
 105 {
 106         struct nlmsghdr *nlh = (struct nlmsghdr *)skb->data;
 107
 108         if (nlh->nlmsg_len < sizeof(*nlh) || skb->len < nlh->nlmsg_len)
 109                 return;
 110
 111         if (!cap_raised(NETLINK_CB(skb).eff_cap, 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
 119 static void dnrmg_receive_user_sk(struct sock *sk, int len)
 120 {
 121         struct sk_buff *skb;
 122
 123         while((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
 124                 dnrmg_receive_user_skb(skb);
 125                 kfree_skb(skb);
 126         }
 127 }
 128
 129 static struct nf_hook_ops dnrmg_ops = {
 130         .hook           = dnrmg_hook,
 131         .pf             = PF_DECnet,
 132         .hooknum        = NF_DN_ROUTE,
 133         .priority       = NF_DN_PRI_DNRTMSG,
 134 };
 135
 136 static int __init init(void)
 137 {
 138         int rv = 0;
 139
 140         dnrmg = netlink_kernel_create(NETLINK_DNRTMSG, dnrmg_receive_user_sk);
 141         if (dnrmg == NULL) {
 142                 printk(KERN_ERR "dn_rtmsg: Cannot create netlink socket");
 143                 return -ENOMEM;
 144         }
 145
 146         rv = nf_register_hook(&dnrmg_ops);
 147         if (rv) {
 148                 sock_release(dnrmg->sk_socket);
 149         }
 150
 151         return rv;
 152 }
 153
 154 static void __exit fini(void)
 155 {
 156         nf_unregister_hook(&dnrmg_ops);
 157         sock_release(dnrmg->sk_socket);
 158 }
 159
 160
 161 MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
 162 MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
 163 MODULE_LICENSE("GPL");
 164
 165 module_init(init);
 166 module_exit(fini);
 167