1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * IP Payload Compression Protocol (IPComp) - RFC3173.
4 *
5 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au>
6 *
7 * Todo:
8 * - Tunable compression parameters.
9 * - Compression stats.
10 * - Adaptive compression.
11 */
12 #include <linux/module.h>
13 #include <linux/err.h>
14 #include <linux/rtnetlink.h>
15 #include <net/ip.h>
16 #include <net/xfrm.h>
17 #include <net/icmp.h>
18 #include <net/ipcomp.h>
19 #include <net/protocol.h>
20 #include <net/sock.h>
21
ipcomp4_err(struct sk_buff * skb,u32 info)22 static int ipcomp4_err(struct sk_buff *skb, u32 info)
23 {
24 struct net *net = dev_net(skb->dev);
25 __be32 spi;
26 const struct iphdr *iph = (const struct iphdr *)skb->data;
27 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2));
28 struct xfrm_state *x;
29
30 switch (icmp_hdr(skb)->type) {
31 case ICMP_DEST_UNREACH:
32 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED)
33 return 0;
34 case ICMP_REDIRECT:
35 break;
36 default:
37 return 0;
38 }
39
40 spi = htonl(ntohs(ipch->cpi));
41 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
42 spi, IPPROTO_COMP, AF_INET);
43 if (!x)
44 return 0;
45
46 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
47 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_COMP);
48 else
49 ipv4_redirect(skb, net, 0, IPPROTO_COMP);
50 xfrm_state_put(x);
51
52 return 0;
53 }
54
55 /* We always hold one tunnel user reference to indicate a tunnel */
ipcomp_tunnel_create(struct xfrm_state * x)56 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
57 {
58 struct net *net = xs_net(x);
59 struct xfrm_state *t;
60
61 t = xfrm_state_alloc(net);
62 if (!t)
63 goto out;
64
65 t->id.proto = IPPROTO_IPIP;
66 t->id.spi = x->props.saddr.a4;
67 t->id.daddr.a4 = x->id.daddr.a4;
68 memcpy(&t->sel, &x->sel, sizeof(t->sel));
69 t->props.family = AF_INET;
70 t->props.mode = x->props.mode;
71 t->props.saddr.a4 = x->props.saddr.a4;
72 t->props.flags = x->props.flags;
73 t->props.extra_flags = x->props.extra_flags;
74 memcpy(&t->mark, &x->mark, sizeof(t->mark));
75
76 if (xfrm_init_state(t))
77 goto error;
78
79 atomic_set(&t->tunnel_users, 1);
80 out:
81 return t;
82
83 error:
84 t->km.state = XFRM_STATE_DEAD;
85 xfrm_state_put(t);
86 t = NULL;
87 goto out;
88 }
89
90 /*
91 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are
92 * always incremented on success.
93 */
ipcomp_tunnel_attach(struct xfrm_state * x)94 static int ipcomp_tunnel_attach(struct xfrm_state *x)
95 {
96 struct net *net = xs_net(x);
97 int err = 0;
98 struct xfrm_state *t;
99 u32 mark = x->mark.v & x->mark.m;
100
101 t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr.a4,
102 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
103 if (!t) {
104 t = ipcomp_tunnel_create(x);
105 if (!t) {
106 err = -EINVAL;
107 goto out;
108 }
109 xfrm_state_insert(t);
110 xfrm_state_hold(t);
111 }
112 x->tunnel = t;
113 atomic_inc(&t->tunnel_users);
114 out:
115 return err;
116 }
117
ipcomp4_init_state(struct xfrm_state * x)118 static int ipcomp4_init_state(struct xfrm_state *x)
119 {
120 int err = -EINVAL;
121
122 x->props.header_len = 0;
123 switch (x->props.mode) {
124 case XFRM_MODE_TRANSPORT:
125 break;
126 case XFRM_MODE_TUNNEL:
127 x->props.header_len += sizeof(struct iphdr);
128 break;
129 default:
130 goto out;
131 }
132
133 err = ipcomp_init_state(x);
134 if (err)
135 goto out;
136
137 if (x->props.mode == XFRM_MODE_TUNNEL) {
138 err = ipcomp_tunnel_attach(x);
139 if (err)
140 goto out;
141 }
142
143 err = 0;
144 out:
145 return err;
146 }
147
ipcomp4_rcv_cb(struct sk_buff * skb,int err)148 static int ipcomp4_rcv_cb(struct sk_buff *skb, int err)
149 {
150 return 0;
151 }
152
153 static const struct xfrm_type ipcomp_type = {
154 .description = "IPCOMP4",
155 .owner = THIS_MODULE,
156 .proto = IPPROTO_COMP,
157 .init_state = ipcomp4_init_state,
158 .destructor = ipcomp_destroy,
159 .input = ipcomp_input,
160 .output = ipcomp_output
161 };
162
163 static struct xfrm4_protocol ipcomp4_protocol = {
164 .handler = xfrm4_rcv,
165 .input_handler = xfrm_input,
166 .cb_handler = ipcomp4_rcv_cb,
167 .err_handler = ipcomp4_err,
168 .priority = 0,
169 };
170
ipcomp4_init(void)171 static int __init ipcomp4_init(void)
172 {
173 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
174 pr_info("%s: can't add xfrm type\n", __func__);
175 return -EAGAIN;
176 }
177 if (xfrm4_protocol_register(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
178 pr_info("%s: can't add protocol\n", __func__);
179 xfrm_unregister_type(&ipcomp_type, AF_INET);
180 return -EAGAIN;
181 }
182 return 0;
183 }
184
ipcomp4_fini(void)185 static void __exit ipcomp4_fini(void)
186 {
187 if (xfrm4_protocol_deregister(&ipcomp4_protocol, IPPROTO_COMP) < 0)
188 pr_info("%s: can't remove protocol\n", __func__);
189 xfrm_unregister_type(&ipcomp_type, AF_INET);
190 }
191
192 module_init(ipcomp4_init);
193 module_exit(ipcomp4_fini);
194
195 MODULE_LICENSE("GPL");
196 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173");
197 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
198
199 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);
200