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 - http://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
28 static struct sock *dnrmg = NULL;
29
30
dnrmg_build_message(struct sk_buff * rt_skb,int * errp)31 static 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
dnrmg_send_peer(struct sk_buff * skb)62 static 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
dnrmg_hook(void * priv,struct sk_buff * skb,const struct nf_hook_state * state)88 static 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
dnrmg_receive_user_skb(struct sk_buff * skb)99 static 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
116 static 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
dn_rtmsg_init(void)123 static 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
dn_rtmsg_fini(void)145 static void __exit dn_rtmsg_fini(void)
146 {
147 nf_unregister_net_hook(&init_net, &dnrmg_ops);
148 netlink_kernel_release(dnrmg);
149 }
150
151
152 MODULE_DESCRIPTION("DECnet Routing Message Grabulator");
153 MODULE_AUTHOR("Steven Whitehouse <steve@chygwyn.com>");
154 MODULE_LICENSE("GPL");
155 MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_DNRTMSG);
156
157 module_init(dn_rtmsg_init);
158 module_exit(dn_rtmsg_fini);
159