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 <net/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
30static struct sock *dnrmg = NULL;
31
32
33static 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_ALIGN(rt_skb->len) +
43	       NLMSG_ALIGN(sizeof(struct nf_dn_rtmsg));
44	skb = nlmsg_new(size, GFP_ATOMIC);
45	if (!skb) {
46		*errp = -ENOMEM;
47		return NULL;
48	}
49	old_tail = skb->tail;
50	nlh = nlmsg_put(skb, 0, 0, 0, size, 0);
51	if (!nlh) {
52		kfree_skb(skb);
53		*errp = -ENOMEM;
54		return NULL;
55	}
56	rtm = (struct nf_dn_rtmsg *)nlmsg_data(nlh);
57	rtm->nfdn_ifindex = rt_skb->dev->ifindex;
58	ptr = NFDN_RTMSG(rtm);
59	skb_copy_from_linear_data(rt_skb, ptr, rt_skb->len);
60	nlh->nlmsg_len = skb->tail - old_tail;
61	return skb;
62}
63
64static 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
90static unsigned int dnrmg_hook(void *priv,
91			struct sk_buff *skb,
92			const struct nf_hook_state *state)
93{
94	dnrmg_send_peer(skb);
95	return NF_ACCEPT;
96}
97
98
99#define RCV_SKB_FAIL(err) do { netlink_ack(skb, nlh, (err)); return; } while (0)
100
101static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
102{
103	struct nlmsghdr *nlh = nlmsg_hdr(skb);
104
105	if (nlh->nlmsg_len < sizeof(*nlh) || 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 struct nf_hook_ops dnrmg_ops __read_mostly = {
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_hook(&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_hook(&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
160