1 /* 2 * IP Payload Compression Protocol (IPComp) - RFC3173. 3 * 4 * Copyright (c) 2003 James Morris <[email protected]> 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 ipv4_update_pmtu(skb, net, info, 0, 0, IPPROTO_COMP, 0); 46 xfrm_state_put(x); 47 } 48 49 /* We always hold one tunnel user reference to indicate a tunnel */ 50 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 51 { 52 struct net *net = xs_net(x); 53 struct xfrm_state *t; 54 55 t = xfrm_state_alloc(net); 56 if (t == NULL) 57 goto out; 58 59 t->id.proto = IPPROTO_IPIP; 60 t->id.spi = x->props.saddr.a4; 61 t->id.daddr.a4 = x->id.daddr.a4; 62 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 63 t->props.family = AF_INET; 64 t->props.mode = x->props.mode; 65 t->props.saddr.a4 = x->props.saddr.a4; 66 t->props.flags = x->props.flags; 67 memcpy(&t->mark, &x->mark, sizeof(t->mark)); 68 69 if (xfrm_init_state(t)) 70 goto error; 71 72 atomic_set(&t->tunnel_users, 1); 73 out: 74 return t; 75 76 error: 77 t->km.state = XFRM_STATE_DEAD; 78 xfrm_state_put(t); 79 t = NULL; 80 goto out; 81 } 82 83 /* 84 * Must be protected by xfrm_cfg_mutex. State and tunnel user references are 85 * always incremented on success. 86 */ 87 static int ipcomp_tunnel_attach(struct xfrm_state *x) 88 { 89 struct net *net = xs_net(x); 90 int err = 0; 91 struct xfrm_state *t; 92 u32 mark = x->mark.v & x->mark.m; 93 94 t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr.a4, 95 x->props.saddr.a4, IPPROTO_IPIP, AF_INET); 96 if (!t) { 97 t = ipcomp_tunnel_create(x); 98 if (!t) { 99 err = -EINVAL; 100 goto out; 101 } 102 xfrm_state_insert(t); 103 xfrm_state_hold(t); 104 } 105 x->tunnel = t; 106 atomic_inc(&t->tunnel_users); 107 out: 108 return err; 109 } 110 111 static int ipcomp4_init_state(struct xfrm_state *x) 112 { 113 int err = -EINVAL; 114 115 x->props.header_len = 0; 116 switch (x->props.mode) { 117 case XFRM_MODE_TRANSPORT: 118 break; 119 case XFRM_MODE_TUNNEL: 120 x->props.header_len += sizeof(struct iphdr); 121 break; 122 default: 123 goto out; 124 } 125 126 err = ipcomp_init_state(x); 127 if (err) 128 goto out; 129 130 if (x->props.mode == XFRM_MODE_TUNNEL) { 131 err = ipcomp_tunnel_attach(x); 132 if (err) 133 goto out; 134 } 135 136 err = 0; 137 out: 138 return err; 139 } 140 141 static const struct xfrm_type ipcomp_type = { 142 .description = "IPCOMP4", 143 .owner = THIS_MODULE, 144 .proto = IPPROTO_COMP, 145 .init_state = ipcomp4_init_state, 146 .destructor = ipcomp_destroy, 147 .input = ipcomp_input, 148 .output = ipcomp_output 149 }; 150 151 static const struct net_protocol ipcomp4_protocol = { 152 .handler = xfrm4_rcv, 153 .err_handler = ipcomp4_err, 154 .no_policy = 1, 155 }; 156 157 static int __init ipcomp4_init(void) 158 { 159 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 160 pr_info("%s: can't add xfrm type\n", __func__); 161 return -EAGAIN; 162 } 163 if (inet_add_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 164 pr_info("%s: can't add protocol\n", __func__); 165 xfrm_unregister_type(&ipcomp_type, AF_INET); 166 return -EAGAIN; 167 } 168 return 0; 169 } 170 171 static void __exit ipcomp4_fini(void) 172 { 173 if (inet_del_protocol(&ipcomp4_protocol, IPPROTO_COMP) < 0) 174 pr_info("%s: can't remove protocol\n", __func__); 175 if (xfrm_unregister_type(&ipcomp_type, AF_INET) < 0) 176 pr_info("%s: can't remove xfrm type\n", __func__); 177 } 178 179 module_init(ipcomp4_init); 180 module_exit(ipcomp4_fini); 181 182 MODULE_LICENSE("GPL"); 183 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173"); 184 MODULE_AUTHOR("James Morris <[email protected]>"); 185 186 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP); 187