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
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 break;
35 case ICMP_REDIRECT:
36 break;
37 default:
38 return 0;
39 }
40
41 spi = htonl(ntohs(ipch->cpi));
42 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
43 spi, IPPROTO_COMP, AF_INET);
44 if (!x)
45 return 0;
46
47 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH)
48 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_COMP);
49 else
50 ipv4_redirect(skb, net, 0, IPPROTO_COMP);
51 xfrm_state_put(x);
52
53 return 0;
54 }
55
56 /* We always hold one tunnel user reference to indicate a tunnel */
57 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x)
58 {
59 struct net *net = xs_net(x);
60 struct xfrm_state *t;
61
62 t = xfrm_state_alloc(net);
63 if (!t)
64 goto out;
65
66 t->id.proto = IPPROTO_IPIP;
67 t->id.spi = x->props.saddr.a4;
68 t->id.daddr.a4 = x->id.daddr.a4;
69 memcpy(&t->sel, &x->sel, sizeof(t->sel));
70 t->props.family = AF_INET;
71 t->props.mode = x->props.mode;
72 t->props.saddr.a4 = x->props.saddr.a4;
73 t->props.flags = x->props.flags;
74 t->props.extra_flags = x->props.extra_flags;
75 memcpy(&t->mark, &x->mark, sizeof(t->mark));
76 t->if_id = x->if_id;
77
78 if (xfrm_init_state(t))
79 goto error;
80
81 atomic_set(&t->tunnel_users, 1);
82 out:
83 return t;
84
85 error:
86 t->km.state = XFRM_STATE_DEAD;
87 xfrm_state_put(t);
88 t = NULL;
89 goto out;
90 }
91
92 /*
93 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are
94 * always incremented on success.
95 */
96 static int ipcomp_tunnel_attach(struct xfrm_state *x)
97 {
98 struct net *net = xs_net(x);
99 int err = 0;
100 struct xfrm_state *t;
101 u32 mark = x->mark.v & x->mark.m;
102
103 t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr.a4,
104 x->props.saddr.a4, IPPROTO_IPIP, AF_INET);
105 if (!t) {
106 t = ipcomp_tunnel_create(x);
107 if (!t) {
108 err = -EINVAL;
109 goto out;
110 }
111 xfrm_state_insert(t);
112 xfrm_state_hold(t);
113 }
114 x->tunnel = t;
115 atomic_inc(&t->tunnel_users);
116 out:
117 return err;
118 }
119
120 static int ipcomp4_init_state(struct xfrm_state *x,
121 struct netlink_ext_ack *extack)
122 {
123 int err = -EINVAL;
124
125 x->props.header_len = 0;
126 switch (x->props.mode) {
127 case XFRM_MODE_TRANSPORT:
128 break;
129 case XFRM_MODE_TUNNEL:
130 x->props.header_len += sizeof(struct iphdr);
131 break;
132 default:
133 NL_SET_ERR_MSG(extack, "Unsupported XFRM mode for IPcomp");
134 goto out;
135 }
136
137 err = ipcomp_init_state(x, extack);
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 NL_SET_ERR_MSG(extack, "Kernel error: failed to initialize the associated state");
145 goto out;
146 }
147 }
148
149 err = 0;
150 out:
151 return err;
152 }
153
154 static int ipcomp4_rcv_cb(struct sk_buff *skb, int err)
155 {
156 return 0;
157 }
158
159 static const struct xfrm_type ipcomp_type = {
160 .owner = THIS_MODULE,
161 .proto = IPPROTO_COMP,
162 .init_state = ipcomp4_init_state,
163 .destructor = ipcomp_destroy,
164 .input = ipcomp_input,
165 .output = ipcomp_output
166 };
167
168 static struct xfrm4_protocol ipcomp4_protocol = {
169 .handler = xfrm4_rcv,
170 .input_handler = xfrm_input,
171 .cb_handler = ipcomp4_rcv_cb,
172 .err_handler = ipcomp4_err,
173 .priority = 0,
174 };
175
176 static int __init ipcomp4_init(void)
177 {
178 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) {
179 pr_info("%s: can't add xfrm type\n", __func__);
180 return -EAGAIN;
181 }
182 if (xfrm4_protocol_register(&ipcomp4_protocol, IPPROTO_COMP) < 0) {
183 pr_info("%s: can't add protocol\n", __func__);
184 xfrm_unregister_type(&ipcomp_type, AF_INET);
185 return -EAGAIN;
186 }
187 return 0;
188 }
189
190 static void __exit ipcomp4_fini(void)
191 {
192 if (xfrm4_protocol_deregister(&ipcomp4_protocol, IPPROTO_COMP) < 0)
193 pr_info("%s: can't remove protocol\n", __func__);
194 xfrm_unregister_type(&ipcomp_type, AF_INET);
195 }
196
197 module_init(ipcomp4_init);
198 module_exit(ipcomp4_fini);
199
200 MODULE_LICENSE("GPL");
201 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173");
202 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>");
203
204 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP);
205
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.