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 __be32 spi; 29 struct iphdr *iph = (struct iphdr *)skb->data; 30 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2)); 31 struct xfrm_state *x; 32 33 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || 34 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 35 return; 36 37 spi = htonl(ntohs(ipch->cpi)); 38 x = xfrm_state_lookup((xfrm_address_t *)&iph->daddr, 39 spi, IPPROTO_COMP, AF_INET); 40 if (!x) 41 return; 42 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/" NIPQUAD_FMT "\n", 43 spi, NIPQUAD(iph->daddr)); 44 xfrm_state_put(x); 45 } 46 47 /* We always hold one tunnel user reference to indicate a tunnel */ 48 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 49 { 50 struct xfrm_state *t; 51 52 t = xfrm_state_alloc(); 53 if (t == NULL) 54 goto out; 55 56 t->id.proto = IPPROTO_IPIP; 57 t->id.spi = x->props.saddr.a4; 58 t->id.daddr.a4 = x->id.daddr.a4; 59 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 60 t->props.family = AF_INET; 61 t->props.mode = x->props.mode; 62 t->props.saddr.a4 = x->props.saddr.a4; 63 t->props.flags = x->props.flags; 64 65 if (xfrm_init_state(t)) 66 goto error; 67 68 atomic_set(&t->tunnel_users, 1); 69 out: 70 return t; 71 72 error: 73 t->km.state = XFRM_STATE_DEAD; 74 xfrm_state_put(t); 75 t = NULL; 76 goto out; 77 } 78 79 /* 80 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are 81 * always incremented on success. 82 */ 83 static int ipcomp_tunnel_attach(struct xfrm_state *x) 84 { 85 int err = 0; 86 struct xfrm_state *t; 87 88 t = xfrm_state_lookup((xfrm_address_t *)&x->id.daddr.a4, 89 x->props.saddr.a4, IPPROTO_IPIP, AF_INET); 90 if (!t) { 91 t = ipcomp_tunnel_create(x); 92 if (!t) { 93 err = -EINVAL; 94 goto out; 95 } 96 xfrm_state_insert(t); 97 xfrm_state_hold(t); 98 } 99 x->tunnel = t; 100 atomic_inc(&t->tunnel_users); 101 out: 102 return err; 103 } 104 105 static int ipcomp4_init_state(struct xfrm_state *x) 106 { 107 int err = -EINVAL; 108 109 x->props.header_len = 0; 110 switch (x->props.mode) { 111 case XFRM_MODE_TRANSPORT: 112 break; 113 case XFRM_MODE_TUNNEL: 114 x->props.header_len += sizeof(struct iphdr); 115 break; 116 default: 117 goto out; 118 } 119 120 err = ipcomp_init_state(x); 121 if (err) 122 goto out; 123 124 if (x->props.mode == XFRM_MODE_TUNNEL) { 125 err = ipcomp_tunnel_attach(x); 126 if (err) 127 goto error_tunnel; 128 } 129 130 err = 0; 131 out: 132 return err; 133 134 error_tunnel: 135 ipcomp_destroy(x); 136 goto out; 137 } 138 139 static const struct xfrm_type ipcomp_type = { 140 .description = "IPCOMP4", 141 .owner = THIS_MODULE, 142 .proto = IPPROTO_COMP, 143 .init_state = ipcomp4_init_state, 144 .destructor = ipcomp_destroy, 145 .input = ipcomp_input, 146 .output = ipcomp_output 147 }; 148 149 static struct net_protocol ipcomp4_protocol = { 150 .handler = xfrm4_rcv, 151 .err_handler = ipcomp4_err, 152 .no_policy = 1, 153 }; 154 155 static int __init ipcomp4_init(void) 156 { 157 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 158 printk(KERN_INFO "ipcomp init: can't add xfrm type\n"); 159 return -EAGAIN; 160 } 161 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 162 printk(KERN_INFO "ipcomp init: can't add protocol\n"); 163 xfrm_unregister_type(&ipcomp_type, AF_INET); 164 return -EAGAIN; 165 } 166 return 0; 167 } 168 169 static void __exit ipcomp4_fini(void) 170 { 171 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) 172 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n"); 173 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 174 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n"); 175 } 176 177 module_init(ipcomp4_init); 178 module_exit(ipcomp4_fini); 179 180 MODULE_LICENSE("GPL"); 181 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173"); 182 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 183 184 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP); 185