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 t->props.extra_flags = x->props.extra_flags; 76 memcpy(&t->mark, &x->mark, sizeof(t->mark)); 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 { 122 int err = -EINVAL; 123 124 x->props.header_len = 0; 125 switch (x->props.mode) { 126 case XFRM_MODE_TRANSPORT: 127 break; 128 case XFRM_MODE_TUNNEL: 129 x->props.header_len += sizeof(struct iphdr); 130 break; 131 default: 132 goto out; 133 } 134 135 err = ipcomp_init_state(x); 136 if (err) 137 goto out; 138 139 if (x->props.mode == XFRM_MODE_TUNNEL) { 140 err = ipcomp_tunnel_attach(x); 141 if (err) 142 goto out; 143 } 144 145 err = 0; 146 out: 147 return err; 148 } 149 150 static const struct xfrm_type ipcomp_type = { 151 .description = "IPCOMP4", 152 .owner = THIS_MODULE, 153 .proto = IPPROTO_COMP, 154 .init_state = ipcomp4_init_state, 155 .destructor = ipcomp_destroy, 156 .input = ipcomp_input, 157 .output = ipcomp_output 158 }; 159 160 static const struct net_protocol ipcomp4_protocol = { 161 .handler = xfrm4_rcv, 162 .err_handler = ipcomp4_err, 163 .no_policy = 1, 164 .netns_ok = 1, 165 }; 166 167 static int __init ipcomp4_init(void) 168 { 169 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 170 pr_info("%s: can't add xfrm type\n", __func__); 171 return -EAGAIN; 172 } 173 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 174 pr_info("%s: can't add protocol\n", __func__); 175 xfrm_unregister_type(&ipcomp_type, AF_INET); 176 return -EAGAIN; 177 } 178 return 0; 179 } 180 181 static void __exit ipcomp4_fini(void) 182 { 183 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) 184 pr_info("%s: can't remove protocol\n", __func__); 185 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 186 pr_info("%s: can't remove xfrm type\n", __func__); 187 } 188 189 module_init(ipcomp4_init); 190 module_exit(ipcomp4_fini); 191 192 MODULE_LICENSE("GPL"); 193 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173"); 194 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 195 196 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP); 197