xref: /openbmc/linux/net/ipv4/ipcomp.c (revision 9d749629)
1 /*
2  * IP Payload Compression Protocol (IPComp) - RFC3173.
3  *
4  * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the Free
8  * Software Foundation; either version 2 of the License, or (at your option)
9  * any later version.
10  *
11  * Todo:
12  *   - Tunable compression parameters.
13  *   - Compression stats.
14  *   - Adaptive compression.
15  */
16 #include <linux/module.h>
17 #include <linux/err.h>
18 #include <linux/rtnetlink.h>
19 #include <net/ip.h>
20 #include <net/xfrm.h>
21 #include <net/icmp.h>
22 #include <net/ipcomp.h>
23 #include <net/protocol.h>
24 #include <net/sock.h>
25 
26 static void ipcomp4_err(struct sk_buff *skb, u32 info)
27 {
28 	struct net *net = dev_net(skb->dev);
29 	__be32 spi;
30 	const struct iphdr *iph = (const struct iphdr *)skb->data;
31 	struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
32 	struct xfrm_state *x;
33 
34 	switch (icmp_hdr(skb)->type) {
35 	case ICMP_DEST_UNREACH:
36 		if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
37 			return;
38 	case ICMP_REDIRECT:
39 		break;
40 	default:
41 		return;
42 	}
43 
44 	spi = htonl(ntohs(ipch->cpi));
45 	x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
46 			      spi, IPPROTO_COMP, AF_INET);
47 	if (!x)
48 		return;
49 
50 	if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH) {
51 		atomic_inc(&flow_cache_genid);
52 		rt_genid_bump(net);
53 
54 		ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_COMP, 0);
55 	} else
56 		ipv4_redirect(skb, net, 0, 0, IPPROTO_COMP, 0);
57 	xfrm_state_put(x);
58 }
59 
60 /* We always hold one tunnel user reference to indicate a tunnel */
61 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
62 {
63 	struct net *net = xs_net(x);
64 	struct xfrm_state *t;
65 
66 	t = xfrm_state_alloc(net);
67 	if (t == NULL)
68 		goto out;
69 
70 	t->id.proto = IPPROTO_IPIP;
71 	t->id.spi = x->props.saddr.a4;
72 	t->id.daddr.a4 = x->id.daddr.a4;
73 	memcpy(&t->sel, &x->sel, sizeof(t->sel));
74 	t->props.family = AF_INET;
75 	t->props.mode = x->props.mode;
76 	t->props.saddr.a4 = x->props.saddr.a4;
77 	t->props.flags = x->props.flags;
78 	memcpy(&t->mark, &x->mark, sizeof(t->mark));
79 
80 	if (xfrm_init_state(t))
81 		goto error;
82 
83 	atomic_set(&t->tunnel_users, 1);
84 out:
85 	return t;
86 
87 error:
88 	t->km.state = XFRM_STATE_DEAD;
89 	xfrm_state_put(t);
90 	t = NULL;
91 	goto out;
92 }
93 
94 /*
95  * Must be protected by xfrm_cfg_mutex.  State and tunnel user references are
96  * always incremented on success.
97  */
98 static int ipcomp_tunnel_attach(struct xfrm_state *x)
99 {
100 	struct net *net = xs_net(x);
101 	int err = 0;
102 	struct xfrm_state *t;
103 	u32 mark = x->mark.v & x->mark.m;
104 
105 	t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr.a4,
106 			      x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
107 	if (!t) {
108 		t = ipcomp_tunnel_create(x);
109 		if (!t) {
110 			err = -EINVAL;
111 			goto out;
112 		}
113 		xfrm_state_insert(t);
114 		xfrm_state_hold(t);
115 	}
116 	x->tunnel = t;
117 	atomic_inc(&t->tunnel_users);
118 out:
119 	return err;
120 }
121 
122 static int ipcomp4_init_state(struct xfrm_state *x)
123 {
124 	int err = -EINVAL;
125 
126 	x->props.header_len = 0;
127 	switch (x->props.mode) {
128 	case XFRM_MODE_TRANSPORT:
129 		break;
130 	case XFRM_MODE_TUNNEL:
131 		x->props.header_len += sizeof(struct iphdr);
132 		break;
133 	default:
134 		goto out;
135 	}
136 
137 	err = ipcomp_init_state(x);
138 	if (err)
139 		goto out;
140 
141 	if (x->props.mode == XFRM_MODE_TUNNEL) {
142 		err = ipcomp_tunnel_attach(x);
143 		if (err)
144 			goto out;
145 	}
146 
147 	err = 0;
148 out:
149 	return err;
150 }
151 
152 static const struct xfrm_type ipcomp_type = {
153 	.description	= "IPCOMP4",
154 	.owner		= THIS_MODULE,
155 	.proto	     	= IPPROTO_COMP,
156 	.init_state	= ipcomp4_init_state,
157 	.destructor	= ipcomp_destroy,
158 	.input		= ipcomp_input,
159 	.output		= ipcomp_output
160 };
161 
162 static const struct net_protocol ipcomp4_protocol = {
163 	.handler	=	xfrm4_rcv,
164 	.err_handler	=	ipcomp4_err,
165 	.no_policy	=	1,
166 	.netns_ok	=	1,
167 };
168 
169 static int __init ipcomp4_init(void)
170 {
171 	if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
172 		pr_info("%s: can't add xfrm type\n", __func__);
173 		return -EAGAIN;
174 	}
175 	if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
176 		pr_info("%s: can't add protocol\n", __func__);
177 		xfrm_unregister_type(&ipcomp_type, AF_INET);
178 		return -EAGAIN;
179 	}
180 	return 0;
181 }
182 
183 static void __exit ipcomp4_fini(void)
184 {
185 	if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0)
186 		pr_info("%s: can't remove protocol\n", __func__);
187 	if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0)
188 		pr_info("%s: can't remove xfrm type\n", __func__);
189 }
190 
191 module_init(ipcomp4_init);
192 module_exit(ipcomp4_fini);
193 
194 MODULE_LICENSE("GPL");
195 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173");
196 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
197 
198 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);
199