LXR linux/net/decnet/netfilter/dn

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * DECnet       An implementation of the DECnet protocol suite for the LINUX
   4 *              operating system.  DECnet is implemented using the  BSD Socket
   5 *              interface as the means of communication with the user level.
   6 *
   7 *              DECnet Routing Message Grabulator
   8 *
   9 *              (C) 2000 ChyGwyn Limited  -  https://www.chygwyn.com/
  10 *
  11 * Author:      Steven Whitehouse <steve@chygwyn.com>
  12 */
  13#include <linux/module.h>
  14#include <linux/skbuff.h>
  15#include <linux/slab.h>
  16#include <linux/init.h>
  17#include <linux/netdevice.h>
  18#include <linux/netfilter.h>
  19#include <linux/spinlock.h>
  20#include <net/netlink.h>
  21#include <linux/netfilter_decnet.h>
  22
  23#include <net/sock.h>
  24#include <net/flow.h>
  25#include <net/dn.h>
  26#include <net/dn_route.h>
  27
  28static struct sock *dnrmg = NULL;
  29
  30
  31static struct sk_buff *dnrmg_build_message(struct sk_buff *rt_skb, int *errp)
  32{
  33        struct sk_buff *skb = NULL;
  34        size_t size;
  35        sk_buff_data_t old_tail;
  36        struct nlmsghdr *nlh;
  37        unsigned char *ptr;
  38        struct nf_dn_rtmsg *rtm;
  39
  40        size = NLMSG_ALIGN(rt_skb->len) +
  41               NLMSG_ALIGN(sizeof(struct nf_dn_rtmsg));
  42        skb = nlmsg_new(size, GFP_ATOMIC);
  43        if (!skb) {
  44                *errp = -ENOMEM;
  45                return NULL;
  46        }
  47        old_tail = skb->tail;
  48        nlh = nlmsg_put(skb, 0, 0, 0, size, 0);
  49        if (!nlh) {
  50                kfree_skb(skb);
  51                *errp = -ENOMEM;
  52                return NULL;
  53        }
  54        rtm = (struct nf_dn_rtmsg *)nlmsg_data(nlh);
  55        rtm->nfdn_ifindex = rt_skb->dev->ifindex;
  56        ptr = NFDN_RTMSG(rtm);
  57        skb_copy_from_linear_data(rt_skb, ptr, rt_skb->len);
  58        nlh->nlmsg_len = skb->tail - old_tail;
  59        return skb;
  60}
  61
  62static void dnrmg_send_peer(struct sk_buff *skb)
  63{
  64        struct sk_buff *skb2;
  65        int status = 0;
  66        int group = 0;
  67        unsigned char flags = *skb->data;
  68
  69        switch (flags & DN_RT_CNTL_MSK) {
  70        case DN_RT_PKT_L1RT:
  71                group = DNRNG_NLGRP_L1;
  72                break;
  73        case DN_RT_PKT_L2RT:
  74                group = DNRNG_NLGRP_L2;
  75                break;
  76        default:
  77                return;
  78        }
  79
  80        skb2 = dnrmg_build_message(skb, &status);
  81        if (skb2 == NULL)
  82                return;
  83        NETLINK_CB(skb2).dst_group = group;
  84        netlink_broadcast(dnrmg, skb2, 0, group, GFP_ATOMIC);
  85}
  86
  87
  88static unsigned int dnrmg_hook(void *priv,
  89                        struct sk_buff *skb,
  90                        const struct nf_hook_state *state)
  91{
  92        dnrmg_send_peer(skb);
  93        return NF_ACCEPT;
  94}
  95
  96
  97#define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err), NULL); return; } while (0)
  98
  99static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
 100{
 101        struct nlmsghdr *nlh = nlmsg_hdr(skb);
 102
 103        if (skb->len < sizeof(*nlh) ||
 104            nlh->nlmsg_len < sizeof(*nlh) ||
 105            skb->len < nlh->nlmsg_len)
 106                return;
 107
 108        if (!netlink_capable(skb, CAP_NET_ADMIN))
 109                RCV_SKB_FAIL(-EPERM);
 110
 111        /* Eventually we might send routing messages too */
 112
 113        RCV_SKB_FAIL(-EINVAL);
 114}
 115
 116static const struct nf_hook_ops dnrmg_ops = {
 117        .hook           = dnrmg_hook,
 118        .pf             = NFPROTO_DECNET,
 119        .hooknum        = NF_DN_ROUTE,
 120        .priority       = NF_DN_PRI_DNRTMSG,
 121};
 122
 123static int __init dn_rtmsg_init(void)
 124{
 125        int rv = 0;
 126        struct netlink_kernel_cfg cfg = {
 127                .groups = DNRNG_NLGRP_MAX,
 128                .input  = dnrmg_receive_user_skb,
 129        };
 130
 131        dnrmg = netlink_kernel_create(&init_net, NETLINK_DNRTMSG, &cfg);
 132        if (dnrmg == NULL) {
 133                printk(KERN_ERR "dn_rtmsg: Cannot create netlink socket");
 134                return -ENOMEM;
 135        }
 136
 137        rv = nf_register_net_hook(&init_net, &dnrmg_ops);
 138        if (rv) {
 139                netlink_kernel_release(dnrmg);
 140        }
 141
 142        return rv;
 143}
 144
 145static void __exit dn_rtmsg_fini(void)
 146{
 147        nf_unregister_net_hook(&init_net, &dnrmg_ops);
 148        netlink_kernel_release(dnrmg);
 149}
 150
 151
 152MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
 153MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
 154MODULE_LICENSE("GPL");
 155MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_DNRTMSG);
 156
 157module_init(dn_rtmsg_init);
 158module_exit(dn_rtmsg_fini);
 159