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 if (icmp_hdr(skb)->type != ICMP_DEST_UNREACH || 35 icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 36 return; 37 38 spi = htonl(ntohs(ipch->cpi)); 39 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 40 spi, IPPROTO_COMP, AF_INET); 41 if (!x) 42 return; 43 NETDEBUG(KERN_DEBUG "pmtu discovery on SA IPCOMP/%08x/%pI4\n", 44 spi, &iph->daddr); 45 xfrm_state_put(x); 46 } 47 48 /* We always hold one tunnel user reference to indicate a tunnel */ 49 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 50 { 51 struct net *net = xs_net(x); 52 struct xfrm_state *t; 53 54 t = xfrm_state_alloc(net); 55 if (t == NULL) 56 goto out; 57 58 t->id.proto = IPPROTO_IPIP; 59 t->id.spi = x->props.saddr.a4; 60 t->id.daddr.a4 = x->id.daddr.a4; 61 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 62 t->props.family = AF_INET; 63 t->props.mode = x->props.mode; 64 t->props.saddr.a4 = x->props.saddr.a4; 65 t->props.flags = x->props.flags; 66 memcpy(&t->mark, &x->mark, sizeof(t->mark)); 67 68 if (xfrm_init_state(t)) 69 goto error; 70 71 atomic_set(&t->tunnel_users, 1); 72 out: 73 return t; 74 75 error: 76 t->km.state = XFRM_STATE_DEAD; 77 xfrm_state_put(t); 78 t = NULL; 79 goto out; 80 } 81 82 /* 83 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are 84 * always incremented on success. 85 */ 86 static int ipcomp_tunnel_attach(struct xfrm_state *x) 87 { 88 struct net *net = xs_net(x); 89 int err = 0; 90 struct xfrm_state *t; 91 u32 mark = x->mark.v & x->mark.m; 92 93 t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr.a4, 94 x->props.saddr.a4, IPPROTO_IPIP, AF_INET); 95 if (!t) { 96 t = ipcomp_tunnel_create(x); 97 if (!t) { 98 err = -EINVAL; 99 goto out; 100 } 101 xfrm_state_insert(t); 102 xfrm_state_hold(t); 103 } 104 x->tunnel = t; 105 atomic_inc(&t->tunnel_users); 106 out: 107 return err; 108 } 109 110 static int ipcomp4_init_state(struct xfrm_state *x) 111 { 112 int err = -EINVAL; 113 114 x->props.header_len = 0; 115 switch (x->props.mode) { 116 case XFRM_MODE_TRANSPORT: 117 break; 118 case XFRM_MODE_TUNNEL: 119 x->props.header_len += sizeof(struct iphdr); 120 break; 121 default: 122 goto out; 123 } 124 125 err = ipcomp_init_state(x); 126 if (err) 127 goto out; 128 129 if (x->props.mode == XFRM_MODE_TUNNEL) { 130 err = ipcomp_tunnel_attach(x); 131 if (err) 132 goto out; 133 } 134 135 err = 0; 136 out: 137 return err; 138 } 139 140 static const struct xfrm_type ipcomp_type = { 141 .description = "IPCOMP4", 142 .owner = THIS_MODULE, 143 .proto = IPPROTO_COMP, 144 .init_state = ipcomp4_init_state, 145 .destructor = ipcomp_destroy, 146 .input = ipcomp_input, 147 .output = ipcomp_output 148 }; 149 150 static const struct net_protocol ipcomp4_protocol = { 151 .handler = xfrm4_rcv, 152 .err_handler = ipcomp4_err, 153 .no_policy = 1, 154 }; 155 156 static int __init ipcomp4_init(void) 157 { 158 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 159 printk(KERN_INFO "ipcomp init: can't add xfrm type\n"); 160 return -EAGAIN; 161 } 162 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 163 printk(KERN_INFO "ipcomp init: can't add protocol\n"); 164 xfrm_unregister_type(&ipcomp_type, AF_INET); 165 return -EAGAIN; 166 } 167 return 0; 168 } 169 170 static void __exit ipcomp4_fini(void) 171 { 172 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) 173 printk(KERN_INFO "ip ipcomp close: can't remove protocol\n"); 174 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 175 printk(KERN_INFO "ip ipcomp close: can't remove xfrm type\n"); 176 } 177 178 module_init(ipcomp4_init); 179 module_exit(ipcomp4_fini); 180 181 MODULE_LICENSE("GPL"); 182 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173"); 183 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 184 185 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP); 186