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/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
  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         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
  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 = 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
  91 static 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
 104 static 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 (!capable(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 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
 126 static 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
 147 static void __exit dn_rtmsg_fini(void)
 148 {
 149         nf_unregister_hook(&dnrmg_ops);
 150         netlink_kernel_release(dnrmg);
 151 }
 152
 153
 154 MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
 155 MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
 156 MODULE_LICENSE("GPL");
 157 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_DNRTMSG);
 158
 159 module_init(dn_rtmsg_init);
 160 module_exit(dn_rtmsg_fini);
 161