1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173
4 *
5 * Copyright (C)2003 USAGI/WIDE Project
6 *
7 * Author Mitsuru KANDA <mk@linux-ipv6.org>
8 */
9 /*
10 * [Memo]
11 *
12 * Outbound:
13 * The compression of IP datagram MUST be done before AH/ESP processing,
14 * fragmentation, and the addition of Hop-by-Hop/Routing header.
15 *
16 * Inbound:
17 * The decompression of IP datagram MUST be done after the reassembly,
18 * AH/ESP processing.
19 */
20
21 #define pr_fmt(fmt) "IPv6: " fmt
22
23 #include <linux/module.h>
24 #include <net/ip.h>
25 #include <net/xfrm.h>
26 #include <net/ipcomp.h>
27 #include <linux/crypto.h>
28 #include <linux/err.h>
29 #include <linux/pfkeyv2.h>
30 #include <linux/random.h>
31 #include <linux/percpu.h>
32 #include <linux/smp.h>
33 #include <linux/list.h>
34 #include <linux/vmalloc.h>
35 #include <linux/rtnetlink.h>
36 #include <net/ip6_route.h>
37 #include <net/icmp.h>
38 #include <net/ipv6.h>
39 #include <net/protocol.h>
40 #include <linux/ipv6.h>
41 #include <linux/icmpv6.h>
42 #include <linux/mutex.h>
43
44 static int ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
45 u8 type, u8 code, int offset, __be32 info)
46 {
47 struct net *net = dev_net(skb->dev);
48 __be32 spi;
49 const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
50 struct ip_comp_hdr *ipcomph =
51 (struct ip_comp_hdr *)(skb->data + offset);
52 struct xfrm_state *x;
53
54 if (type != ICMPV6_PKT_TOOBIG &&
55 type != NDISC_REDIRECT)
56 return 0;
57
58 spi = htonl(ntohs(ipcomph->cpi));
59 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
60 spi, IPPROTO_COMP, AF_INET6);
61 if (!x)
62 return 0;
63
64 if (type == NDISC_REDIRECT)
65 ip6_redirect(skb, net, skb->dev->ifindex, 0,
66 sock_net_uid(net, NULL));
67 else
68 ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
69 xfrm_state_put(x);
70
71 return 0;
72 }
73
74 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
75 {
76 struct net *net = xs_net(x);
77 struct xfrm_state *t = NULL;
78
79 t = xfrm_state_alloc(net);
80 if (!t)
81 goto out;
82
83 t->id.proto = IPPROTO_IPV6;
84 t->id.spi = xfrm6_tunnel_alloc_spi(net, (xfrm_address_t *)&x->props.saddr);
85 if (!t->id.spi)
86 goto error;
87
88 memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
89 memcpy(&t->sel, &x->sel, sizeof(t->sel));
90 t->props.family = AF_INET6;
91 t->props.mode = x->props.mode;
92 memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
93 memcpy(&t->mark, &x->mark, sizeof(t->mark));
94 t->if_id = x->if_id;
95
96 if (xfrm_init_state(t))
97 goto error;
98
99 atomic_set(&t->tunnel_users, 1);
100
101 out:
102 return t;
103
104 error:
105 t->km.state = XFRM_STATE_DEAD;
106 xfrm_state_put(t);
107 t = NULL;
108 goto out;
109 }
110
111 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
112 {
113 struct net *net = xs_net(x);
114 int err = 0;
115 struct xfrm_state *t = NULL;
116 __be32 spi;
117 u32 mark = x->mark.m & x->mark.v;
118
119 spi = xfrm6_tunnel_spi_lookup(net, (xfrm_address_t *)&x->props.saddr);
120 if (spi)
121 t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr,
122 spi, IPPROTO_IPV6, AF_INET6);
123 if (!t) {
124 t = ipcomp6_tunnel_create(x);
125 if (!t) {
126 err = -EINVAL;
127 goto out;
128 }
129 xfrm_state_insert(t);
130 xfrm_state_hold(t);
131 }
132 x->tunnel = t;
133 atomic_inc(&t->tunnel_users);
134
135 out:
136 return err;
137 }
138
139 static int ipcomp6_init_state(struct xfrm_state *x,
140 struct netlink_ext_ack *extack)
141 {
142 int err = -EINVAL;
143
144 x->props.header_len = 0;
145 switch (x->props.mode) {
146 case XFRM_MODE_TRANSPORT:
147 break;
148 case XFRM_MODE_TUNNEL:
149 x->props.header_len += sizeof(struct ipv6hdr);
150 break;
151 default:
152 NL_SET_ERR_MSG(extack, "Unsupported XFRM mode for IPcomp");
153 goto out;
154 }
155
156 err = ipcomp_init_state(x, extack);
157 if (err)
158 goto out;
159
160 if (x->props.mode == XFRM_MODE_TUNNEL) {
161 err = ipcomp6_tunnel_attach(x);
162 if (err) {
163 NL_SET_ERR_MSG(extack, "Kernel error: failed to initialize the associated state");
164 goto out;
165 }
166 }
167
168 err = 0;
169 out:
170 return err;
171 }
172
173 static int ipcomp6_rcv_cb(struct sk_buff *skb, int err)
174 {
175 return 0;
176 }
177
178 static const struct xfrm_type ipcomp6_type = {
179 .owner = THIS_MODULE,
180 .proto = IPPROTO_COMP,
181 .init_state = ipcomp6_init_state,
182 .destructor = ipcomp_destroy,
183 .input = ipcomp_input,
184 .output = ipcomp_output,
185 };
186
187 static struct xfrm6_protocol ipcomp6_protocol = {
188 .handler = xfrm6_rcv,
189 .input_handler = xfrm_input,
190 .cb_handler = ipcomp6_rcv_cb,
191 .err_handler = ipcomp6_err,
192 .priority = 0,
193 };
194
195 static int __init ipcomp6_init(void)
196 {
197 if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
198 pr_info("%s: can't add xfrm type\n", __func__);
199 return -EAGAIN;
200 }
201 if (xfrm6_protocol_register(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
202 pr_info("%s: can't add protocol\n", __func__);
203 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
204 return -EAGAIN;
205 }
206 return 0;
207 }
208
209 static void __exit ipcomp6_fini(void)
210 {
211 if (xfrm6_protocol_deregister(&ipcomp6_protocol, IPPROTO_COMP) < 0)
212 pr_info("%s: can't remove protocol\n", __func__);
213 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
214 }
215
216 module_init(ipcomp6_init);
217 module_exit(ipcomp6_fini);
218 MODULE_LICENSE("GPL");
219 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
220 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
221
222 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);
223
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