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 ipcomp4_err(struct sk_buff * skb,u32 info)22 static 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 break; 35 case ICMP_REDIRECT: 36 break; 37 default: 38 return 0; 39 } 40 41 spi = htonl(ntohs(ipch->cpi)); 42 x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr, 43 spi, IPPROTO_COMP, AF_INET); 44 if (!x) 45 return 0; 46 47 if (icmp_hdr(skb)->type == ICMP_DEST_UNREACH) 48 ipv4_update_pmtu(skb, net, info, 0, IPPROTO_COMP); 49 else 50 ipv4_redirect(skb, net, 0, IPPROTO_COMP); 51 xfrm_state_put(x); 52 53 return 0; 54 } 55 56 /* We always hold one tunnel user reference to indicate a tunnel */ ipcomp_tunnel_create(struct xfrm_state * x)57 static struct xfrm_state *ipcomp_tunnel_create(struct xfrm_state *x) 58 { 59 struct net *net = xs_net(x); 60 struct xfrm_state *t; 61 62 t = xfrm_state_alloc(net); 63 if (!t) 64 goto out; 65 66 t->id.proto = IPPROTO_IPIP; 67 t->id.spi = x->props.saddr.a4; 68 t->id.daddr.a4 = x->id.daddr.a4; 69 memcpy(&t->sel, &x->sel, sizeof(t->sel)); 70 t->props.family = AF_INET; 71 t->props.mode = x->props.mode; 72 t->props.saddr.a4 = x->props.saddr.a4; 73 t->props.flags = x->props.flags; 74 t->props.extra_flags = x->props.extra_flags; 75 memcpy(&t->mark, &x->mark, sizeof(t->mark)); 76 t->if_id = x->if_id; 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 */ ipcomp_tunnel_attach(struct xfrm_state * x)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 ipcomp4_init_state(struct xfrm_state * x,struct netlink_ext_ack * extack)120 static int ipcomp4_init_state(struct xfrm_state *x, 121 struct netlink_ext_ack *extack) 122 { 123 int err = -EINVAL; 124 125 x->props.header_len = 0; 126 switch (x->props.mode) { 127 case XFRM_MODE_TRANSPORT: 128 break; 129 case XFRM_MODE_TUNNEL: 130 x->props.header_len += sizeof(struct iphdr); 131 break; 132 default: 133 NL_SET_ERR_MSG(extack, "Unsupported XFRM mode for IPcomp"); 134 goto out; 135 } 136 137 err = ipcomp_init_state(x, extack); 138 if (err) 139 goto out; 140 141 if (x->props.mode == XFRM_MODE_TUNNEL) { 142 err = ipcomp_tunnel_attach(x); 143 if (err) { 144 NL_SET_ERR_MSG(extack, "Kernel error: failed to initialize the associated state"); 145 goto out; 146 } 147 } 148 149 err = 0; 150 out: 151 return err; 152 } 153 ipcomp4_rcv_cb(struct sk_buff * skb,int err)154 static int ipcomp4_rcv_cb(struct sk_buff *skb, int err) 155 { 156 return 0; 157 } 158 159 static const struct xfrm_type ipcomp_type = { 160 .owner = THIS_MODULE, 161 .proto = IPPROTO_COMP, 162 .init_state = ipcomp4_init_state, 163 .destructor = ipcomp_destroy, 164 .input = ipcomp_input, 165 .output = ipcomp_output 166 }; 167 168 static struct xfrm4_protocol ipcomp4_protocol = { 169 .handler = xfrm4_rcv, 170 .input_handler = xfrm_input, 171 .cb_handler = ipcomp4_rcv_cb, 172 .err_handler = ipcomp4_err, 173 .priority = 0, 174 }; 175 ipcomp4_init(void)176 static int __init ipcomp4_init(void) 177 { 178 if (xfrm_register_type(&ipcomp_type, AF_INET) < 0) { 179 pr_info("%s: can't add xfrm type\n", __func__); 180 return -EAGAIN; 181 } 182 if (xfrm4_protocol_register(&ipcomp4_protocol, IPPROTO_COMP) < 0) { 183 pr_info("%s: can't add protocol\n", __func__); 184 xfrm_unregister_type(&ipcomp_type, AF_INET); 185 return -EAGAIN; 186 } 187 return 0; 188 } 189 ipcomp4_fini(void)190 static void __exit ipcomp4_fini(void) 191 { 192 if (xfrm4_protocol_deregister(&ipcomp4_protocol, IPPROTO_COMP) < 0) 193 pr_info("%s: can't remove protocol\n", __func__); 194 xfrm_unregister_type(&ipcomp_type, AF_INET); 195 } 196 197 module_init(ipcomp4_init); 198 module_exit(ipcomp4_fini); 199 200 MODULE_LICENSE("GPL"); 201 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp/IPv4) - RFC3173"); 202 MODULE_AUTHOR("James Morris <jmorris@intercode.com.au>"); 203 204 MODULE_ALIAS_XFRM_TYPE(AF_INET, XFRM_PROTO_COMP); 205