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 void 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; 38 case ICMP_REDIRECT: 39 break; 40 default: 41 return; 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; 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 57 /* We always hold one tunnel user reference to indicate a tunnel */ 58 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 59 { 60 struct net *net = xs_net(x); 61 struct xfrm_state *t; 62 63 t = xfrm_state_alloc(net); 64 if (t == NULL) 65 goto out; 66 67 t->id.proto = IPPROTO_IPIP; 68 t->id.spi = x->props.saddr.a4; 69 t->id.daddr.a4 = x->id.daddr.a4; 70 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 71 t->props.family = AF_INET; 72 t->props.mode = x->props.mode; 73 t->props.saddr.a4 = x->props.saddr.a4; 74 t->props.flags = x->props.flags; 75 memcpy(&t->mark, &x->mark, sizeof(t->mark)); 76 77 if (xfrm_init_state(t)) 78 goto error; 79 80 atomic_set(&t->tunnel_users, 1); 81 out: 82 return t; 83 84 error: 85 t->km.state = XFRM_STATE_DEAD; 86 xfrm_state_put(t); 87 t = NULL; 88 goto out; 89 } 90 91 /* 92 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are 93 * always incremented on success. 94 */ 95 static int ipcomp_tunnel_attach(struct xfrm_state *x) 96 { 97 struct net *net = xs_net(x); 98 int err = 0; 99 struct xfrm_state *t; 100 u32 mark = x->mark.v & x->mark.m; 101 102 t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr.a4, 103 x->props.saddr.a4, IPPROTO_IPIP, AF_INET); 104 if (!t) { 105 t = ipcomp_tunnel_create(x); 106 if (!t) { 107 err = -EINVAL; 108 goto out; 109 } 110 xfrm_state_insert(t); 111 xfrm_state_hold(t); 112 } 113 x->tunnel = t; 114 atomic_inc(&t->tunnel_users); 115 out: 116 return err; 117 } 118 119 static int ipcomp4_init_state(struct xfrm_state *x) 120 { 121 int err = -EINVAL; 122 123 x->props.header_len = 0; 124 switch (x->props.mode) { 125 case XFRM_MODE_TRANSPORT: 126 break; 127 case XFRM_MODE_TUNNEL: 128 x->props.header_len += sizeof(struct iphdr); 129 break; 130 default: 131 goto out; 132 } 133 134 err = ipcomp_init_state(x); 135 if (err) 136 goto out; 137 138 if (x->props.mode == XFRM_MODE_TUNNEL) { 139 err = ipcomp_tunnel_attach(x); 140 if (err) 141 goto out; 142 } 143 144 err = 0; 145 out: 146 return err; 147 } 148 149 static const struct xfrm_type ipcomp_type = { 150 .description = "IPCOMP4", 151 .owner = THIS_MODULE, 152 .proto = IPPROTO_COMP, 153 .init_state = ipcomp4_init_state, 154 .destructor = ipcomp_destroy, 155 .input = ipcomp_input, 156 .output = ipcomp_output 157 }; 158 159 static const struct net_protocol ipcomp4_protocol = { 160 .handler = xfrm4_rcv, 161 .err_handler = ipcomp4_err, 162 .no_policy = 1, 163 }; 164 165 static int __init ipcomp4_init(void) 166 { 167 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 168 pr_info("%s: can't add xfrm type\n", __func__); 169 return -EAGAIN; 170 } 171 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 172 pr_info("%s: can't add protocol\n", __func__); 173 xfrm_unregister_type(&ipcomp_type, AF_INET); 174 return -EAGAIN; 175 } 176 return 0; 177 } 178 179 static void __exit ipcomp4_fini(void) 180 { 181 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) 182 pr_info("%s: can't remove protocol\n", __func__); 183 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 184 pr_info("%s: can't remove xfrm type\n", __func__); 185 } 186 187 module_init(ipcomp4_init); 188 module_exit(ipcomp4_fini); 189 190 MODULE_LICENSE("GPL"); 191 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173"); 192 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 193 194 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP); 195