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 int 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 0; 38 case ICMP_REDIRECT: 39 break; 40 default: 41 return 0; 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 0; 49 50 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH) 51 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_COMP, 0); 52 else 53 ipv4_redirect(skb, net, 0, 0, IPPROTO_COMP, 0); 54 xfrm_state_put(x); 55 56 return 0; 57 } 58 59 /* We always hold one tunnel user reference to indicate a tunnel */ 60 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 61 { 62 struct net *net = xs_net(x); 63 struct xfrm_state *t; 64 65 t = xfrm_state_alloc(net); 66 if (t == NULL) 67 goto out; 68 69 t->id.proto = IPPROTO_IPIP; 70 t->id.spi = x->props.saddr.a4; 71 t->id.daddr.a4 = x->id.daddr.a4; 72 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 73 t->props.family = AF_INET; 74 t->props.mode = x->props.mode; 75 t->props.saddr.a4 = x->props.saddr.a4; 76 t->props.flags = x->props.flags; 77 t->props.extra_flags = x->props.extra_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 int ipcomp4_rcv_cb(struct sk_buff *skb, int err) 153 { 154 return 0; 155 } 156 157 static const struct xfrm_type ipcomp_type = { 158 .description = "IPCOMP4", 159 .owner = THIS_MODULE, 160 .proto = IPPROTO_COMP, 161 .init_state = ipcomp4_init_state, 162 .destructor = ipcomp_destroy, 163 .input = ipcomp_input, 164 .output = ipcomp_output 165 }; 166 167 static struct xfrm4_protocol ipcomp4_protocol = { 168 .handler = xfrm4_rcv, 169 .input_handler = xfrm_input, 170 .cb_handler = ipcomp4_rcv_cb, 171 .err_handler = ipcomp4_err, 172 .priority = 0, 173 }; 174 175 static int __init ipcomp4_init(void) 176 { 177 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 178 pr_info("%s: can't add xfrm type\n", __func__); 179 return -EAGAIN; 180 } 181 if (xfrm4_protocol_register(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 182 pr_info("%s: can't add protocol\n", __func__); 183 xfrm_unregister_type(&ipcomp_type, AF_INET); 184 return -EAGAIN; 185 } 186 return 0; 187 } 188 189 static void __exit ipcomp4_fini(void) 190 { 191 if (xfrm4_protocol_deregister(&ipcomp4_protocol, IPPROTO_COMP) < 0) 192 pr_info("%s: can't remove protocol\n", __func__); 193 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 194 pr_info("%s: can't remove xfrm type\n", __func__); 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