1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * IP Payload Compression Protocol (IPComp) - RFC3173. 4 * 5 * Copyright (c) 2003 James Morris <jmorris@intercode.com.au> 6 * 7 * Todo: 8 * - Tunable compression parameters. 9 * - Compression stats. 10 * - Adaptive compression. 11 */ 12#include <linux/module.h> 13#include <linux/err.h> 14#include <linux/rtnetlink.h> 15#include <net/ip.h> 16#include <net/xfrm.h> 17#include <net/icmp.h> 18#include <net/ipcomp.h> 19#include <net/protocol.h> 20#include <net/sock.h> 21 22static int ipcomp4_err(struct sk_buff *skb, u32 info) 23{ 24 struct net *net = dev_net(skb->dev); 25 __be32 spi; 26 const struct iphdr *iph = (const struct iphdr *)skb->data; 27 struct ip_comp_hdr *ipch = (struct ip_comp_hdr *)(skb->data+(iph->ihl<<2)); 28 struct xfrm_state *x; 29 30 switch (icmp_hdr(skb)->type) { 31 case ICMP_DEST_UNREACH: 32 if (icmp_hdr(skb)->code != ICMP_FRAG_NEEDED) 33 return 0; 34 case ICMP_REDIRECT: 35 break; 36 default: 37 return 0; 38 } 39 40 spi = htonl(ntohs(ipch->cpi)); 41 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 42 spi, IPPROTO_COMP, AF_INET); 43 if (!x) 44 return 0; 45 46 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH) 47 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_COMP); 48 else 49 ipv4_redirect(skb, net, 0, IPPROTO_COMP); 50 xfrm_state_put(x); 51 52 return 0; 53} 54 55/* We always hold one tunnel user reference to indicate a tunnel */ 56static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 57{ 58 struct net *net = xs_net(x); 59 struct xfrm_state *t; 60 61 t = xfrm_state_alloc(net); 62 if (!t) 63 goto out; 64 65 t->id.proto = IPPROTO_IPIP; 66 t->id.spi = x->props.saddr.a4; 67 t->id.daddr.a4 = x->id.daddr.a4; 68 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 69 t->props.family = AF_INET; 70 t->props.mode = x->props.mode; 71 t->props.saddr.a4 = x->props.saddr.a4; 72 t->props.flags = x->props.flags; 73 t->props.extra_flags = x->props.extra_flags; 74 memcpy(&t->mark, &x->mark, sizeof(t->mark)); 75 t->if_id = x->if_id; 76 77 if (xfrm_init_state(t)) 78 goto error; 79 80 atomic_set(&t->tunnel_users, 1); 81out: 82 return t; 83 84error: 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 */ 95static 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); 115out: 116 return err; 117} 118 119static 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; 145out: 146 return err; 147} 148 149static int ipcomp4_rcv_cb(struct sk_buff *skb, int err) 150{ 151 return 0; 152} 153 154static const struct xfrm_type ipcomp_type = { 155 .description = "IPCOMP4", 156 .owner = THIS_MODULE, 157 .proto = IPPROTO_COMP, 158 .init_state = ipcomp4_init_state, 159 .destructor = ipcomp_destroy, 160 .input = ipcomp_input, 161 .output = ipcomp_output 162}; 163 164static struct xfrm4_protocol ipcomp4_protocol = { 165 .handler = xfrm4_rcv, 166 .input_handler = xfrm_input, 167 .cb_handler = ipcomp4_rcv_cb, 168 .err_handler = ipcomp4_err, 169 .priority = 0, 170}; 171 172static int __init ipcomp4_init(void) 173{ 174 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 175 pr_info("%s: can't add xfrm type\n", __func__); 176 return -EAGAIN; 177 } 178 if (xfrm4_protocol_register(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 179 pr_info("%s: can't add protocol\n", __func__); 180 xfrm_unregister_type(&ipcomp_type, AF_INET); 181 return -EAGAIN; 182 } 183 return 0; 184} 185 186static void __exit ipcomp4_fini(void) 187{ 188 if (xfrm4_protocol_deregister(&ipcomp4_protocol, IPPROTO_COMP) < 0) 189 pr_info("%s: can't remove protocol\n", __func__); 190 xfrm_unregister_type(&ipcomp_type, AF_INET); 191} 192 193module_init(ipcomp4_init); 194module_exit(ipcomp4_fini); 195 196MODULE_LICENSE("GPL"); 197MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173"); 198MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 199 200MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP); 201