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(dev: 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, mark: skb->mark, daddr: (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, mtu: info, oif: 0, IPPROTO_COMP); |
49 | else |
50 | ipv4_redirect(skb, net, oif: 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(x: t)) |
79 | goto error; |
80 | |
81 | atomic_set(v: &t->tunnel_users, i: 1); |
82 | out: |
83 | return t; |
84 | |
85 | error: |
86 | t->km.state = XFRM_STATE_DEAD; |
87 | xfrm_state_put(x: 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, daddr: (xfrm_address_t *)&x->id.daddr.a4, |
104 | spi: 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(x: t); |
112 | xfrm_state_hold(x: t); |
113 | } |
114 | x->tunnel = t; |
115 | atomic_inc(v: &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(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(handler: &ipcomp4_protocol, IPPROTO_COMP) < 0) { |
183 | pr_info("%s: can't add protocol\n" , __func__); |
184 | xfrm_unregister_type(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(handler: &ipcomp4_protocol, IPPROTO_COMP) < 0) |
193 | pr_info("%s: can't remove protocol\n" , __func__); |
194 | xfrm_unregister_type(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 | |