// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* DECnet An implementation of the DECnet protocol suite for the LINUX
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* operating system. DECnet is implemented using the BSD Socket
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* interface as the means of communication with the user level.
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*
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* DECnet Routing Message Grabulator
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*
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* (C) 2000 ChyGwyn Limited - https://www.chygwyn.com/
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*
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* Author: Steven Whitehouse <steve@chygwyn.com>
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/netdevice.h>
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#include <linux/netfilter.h>
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#include <linux/spinlock.h>
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#include <net/netlink.h>
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#include <linux/netfilter_decnet.h>
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#include <net/sock.h>
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#include <net/flow.h>
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#include <net/dn.h>
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#include <net/dn_route.h>
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static struct sock *dnrmg = NULL;
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static struct sk_buff *dnrmg_build_message(struct sk_buff *rt_skb, int *errp)
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{
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struct sk_buff *skb = NULL;
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size_t size;
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sk_buff_data_t old_tail;
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struct nlmsghdr *nlh;
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unsigned char *ptr;
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struct nf_dn_rtmsg *rtm;
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size = NLMSG_ALIGN(rt_skb->len) +
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NLMSG_ALIGN(sizeof(struct nf_dn_rtmsg));
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skb = nlmsg_new(size, GFP_ATOMIC);
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if (!skb) {
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*errp = -ENOMEM;
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return NULL;
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}
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old_tail = skb->tail;
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nlh = nlmsg_put(skb, 0, 0, 0, size, 0);
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if (!nlh) {
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kfree_skb(skb);
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*errp = -ENOMEM;
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return NULL;
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}
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rtm = (struct nf_dn_rtmsg *)nlmsg_data(nlh);
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rtm->nfdn_ifindex = rt_skb->dev->ifindex;
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ptr = NFDN_RTMSG(rtm);
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skb_copy_from_linear_data(rt_skb, ptr, rt_skb->len);
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nlh->nlmsg_len = skb->tail - old_tail;
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return skb;
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}
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static void dnrmg_send_peer(struct sk_buff *skb)
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{
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struct sk_buff *skb2;
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int status = 0;
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int group = 0;
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unsigned char flags = *skb->data;
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switch (flags & DN_RT_CNTL_MSK) {
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case DN_RT_PKT_L1RT:
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group = DNRNG_NLGRP_L1;
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break;
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case DN_RT_PKT_L2RT:
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group = DNRNG_NLGRP_L2;
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break;
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default:
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return;
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}
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skb2 = dnrmg_build_message(skb, &status);
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if (skb2 == NULL)
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return;
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NETLINK_CB(skb2).dst_group = group;
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netlink_broadcast(dnrmg, skb2, 0, group, GFP_ATOMIC);
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}
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static unsigned int dnrmg_hook(void *priv,
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struct sk_buff *skb,
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const struct nf_hook_state *state)
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{
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dnrmg_send_peer(skb);
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return NF_ACCEPT;
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}
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#define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err), NULL); return; } while (0)
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static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
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{
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struct nlmsghdr *nlh = nlmsg_hdr(skb);
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if (skb->len < sizeof(*nlh) ||
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nlh->nlmsg_len < sizeof(*nlh) ||
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skb->len < nlh->nlmsg_len)
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return;
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if (!netlink_capable(skb, CAP_NET_ADMIN))
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RCV_SKB_FAIL(-EPERM);
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/* Eventually we might send routing messages too */
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RCV_SKB_FAIL(-EINVAL);
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}
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static const struct nf_hook_ops dnrmg_ops = {
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.hook = dnrmg_hook,
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.pf = NFPROTO_DECNET,
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.hooknum = NF_DN_ROUTE,
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.priority = NF_DN_PRI_DNRTMSG,
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};
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static int __init dn_rtmsg_init(void)
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{
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int rv = 0;
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struct netlink_kernel_cfg cfg = {
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.groups = DNRNG_NLGRP_MAX,
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.input = dnrmg_receive_user_skb,
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};
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dnrmg = netlink_kernel_create(&init_net, NETLINK_DNRTMSG, &cfg);
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if (dnrmg == NULL) {
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printk(KERN_ERR "dn_rtmsg: Cannot create netlink socket");
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return -ENOMEM;
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}
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rv = nf_register_net_hook(&init_net, &dnrmg_ops);
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if (rv) {
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netlink_kernel_release(dnrmg);
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}
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return rv;
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}
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static void __exit dn_rtmsg_fini(void)
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{
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nf_unregister_net_hook(&init_net, &dnrmg_ops);
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netlink_kernel_release(dnrmg);
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}
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MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
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MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
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MODULE_LICENSE("GPL");
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MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_DNRTMSG);
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module_init(dn_rtmsg_init);
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module_exit(dn_rtmsg_fini);
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