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 static struct sock *dnrmg = NULL;
  30
  31
  32 static 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
  55 nlmsg_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
  64 static 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
  90 static 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
 103 static 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
 118 static 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
 125 static 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
 146 static void __exit dn_rtmsg_fini(void)
 147 {
 148         nf_unregister_hook(&dnrmg_ops);
 149         netlink_kernel_release(dnrmg);
 150 }
 151
 152
 153 MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
 154 MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
 155 MODULE_LICENSE("GPL");
 156 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_DNRTMSG);
 157
 158 module_init(dn_rtmsg_init);
 159 module_exit(dn_rtmsg_fini);
 160