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
30 static struct sock *dnrmg = NULL;
31
32
dnrmg_build_message(struct sk_buff * rt_skb,int * errp)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_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
dnrmg_send_peer(struct sk_buff * skb)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
dnrmg_hook(const struct nf_hook_ops * ops,struct sk_buff * skb,const struct net_device * in,const struct net_device * out,int (* okfn)(struct sk_buff *))90 static unsigned int dnrmg_hook(const struct nf_hook_ops *ops,
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
dnrmg_receive_user_skb(struct sk_buff * skb)103 static inline void dnrmg_receive_user_skb(struct sk_buff *skb)
104 {
105 struct nlmsghdr *nlh = nlmsg_hdr(skb);
106
107 if (skb->len < sizeof(*nlh) ||
108 nlh->nlmsg_len < sizeof(*nlh) ||
109 skb->len < nlh->nlmsg_len)
110 return;
111
112 if (!netlink_capable(skb, CAP_NET_ADMIN))
113 RCV_SKB_FAIL(-EPERM);
114
115 /* Eventually we might send routing messages too */
116
117 RCV_SKB_FAIL(-EINVAL);
118 }
119
120 static struct nf_hook_ops dnrmg_ops __read_mostly = {
121 .hook = dnrmg_hook,
122 .pf = NFPROTO_DECNET,
123 .hooknum = NF_DN_ROUTE,
124 .priority = NF_DN_PRI_DNRTMSG,
125 };
126
dn_rtmsg_init(void)127 static int __init dn_rtmsg_init(void)
128 {
129 int rv = 0;
130 struct netlink_kernel_cfg cfg = {
131 .groups = DNRNG_NLGRP_MAX,
132 .input = dnrmg_receive_user_skb,
133 };
134
135 dnrmg = netlink_kernel_create(&init_net, NETLINK_DNRTMSG, &cfg);
136 if (dnrmg == NULL) {
137 printk(KERN_ERR "dn_rtmsg: Cannot create netlink socket");
138 return -ENOMEM;
139 }
140
141 rv = nf_register_hook(&dnrmg_ops);
142 if (rv) {
143 netlink_kernel_release(dnrmg);
144 }
145
146 return rv;
147 }
148
dn_rtmsg_fini(void)149 static void __exit dn_rtmsg_fini(void)
150 {
151 nf_unregister_hook(&dnrmg_ops);
152 netlink_kernel_release(dnrmg);
153 }
154
155
156 MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
157 MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
158 MODULE_LICENSE("GPL");
159 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_DNRTMSG);
160
161 module_init(dn_rtmsg_init);
162 module_exit(dn_rtmsg_fini);
163
164