net/ipv6/ipcomp6.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173
   4  *
   5  * Copyright (C)2003 USAGI/WIDE Project
   6  *
   7  * Author       Mitsuru KANDA  <mk@linux-ipv6.org>
   8  */
   9 /*
  10  * [Memo]
  11  *
  12  * Outbound:
  13  *  The compression of IP datagram MUST be done before AH/ESP processing,
  14  *  fragmentation, and the addition of Hop-by-Hop/Routing header.
  15  *
  16  * Inbound:
  17  *  The decompression of IP datagram MUST be done after the reassembly,
  18  *  AH/ESP processing.
  19  */
  20
  21 #define pr_fmt(fmt) "IPv6: " fmt
  22
  23 #include <linux/module.h>
  24 #include <net/ip.h>
  25 #include <net/xfrm.h>
  26 #include <net/ipcomp.h>
  27 #include <linux/crypto.h>
  28 #include <linux/err.h>
  29 #include <linux/pfkeyv2.h>
  30 #include <linux/random.h>
  31 #include <linux/percpu.h>
  32 #include <linux/smp.h>
  33 #include <linux/list.h>
  34 #include <linux/vmalloc.h>
  35 #include <linux/rtnetlink.h>
  36 #include <net/ip6_route.h>
  37 #include <net/icmp.h>
  38 #include <net/ipv6.h>
  39 #include <net/protocol.h>
  40 #include <linux/ipv6.h>
  41 #include <linux/icmpv6.h>
  42 #include <linux/mutex.h>
  43
  44 static int ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
  45                                 u8 type, u8 code, int offset, __be32 info)
  46 {
  47         struct net *net = dev_net(skb->dev);
  48         __be32 spi;
  49         const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
  50         struct ip_comp_hdr *ipcomph =
  51                 (struct ip_comp_hdr *)(skb->data + offset);
  52         struct xfrm_state *x;
  53
  54         if (type != ICMPV6_PKT_TOOBIG &&
  55             type != NDISC_REDIRECT)
  56                 return 0;
  57
  58         spi = htonl(ntohs(ipcomph->cpi));
  59         x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
  60                               spi, IPPROTO_COMP, AF_INET6);
  61         if (!x)
  62                 return 0;
  63
  64         if (type == NDISC_REDIRECT)
  65                 ip6_redirect(skb, net, skb->dev->ifindex, 0,
  66                              sock_net_uid(net, NULL));
  67         else
  68                 ip6_update_pmtu(skb, net, info, 0, 0, sock_net_uid(net, NULL));
  69         xfrm_state_put(x);
  70
  71         return 0;
  72 }
  73
  74 static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
  75 {
  76         struct net *net = xs_net(x);
  77         struct xfrm_state *t = NULL;
  78
  79         t = xfrm_state_alloc(net);
  80         if (!t)
  81                 goto out;
  82
  83         t->id.proto = IPPROTO_IPV6;
  84         t->id.spi = xfrm6_tunnel_alloc_spi(net, (xfrm_address_t *)&x->props.saddr);
  85         if (!t->id.spi)
  86                 goto error;
  87
  88         memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
  89         memcpy(&t->sel, &x->sel, sizeof(t->sel));
  90         t->props.family = AF_INET6;
  91         t->props.mode = x->props.mode;
  92         memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
  93         memcpy(&t->mark, &x->mark, sizeof(t->mark));
  94         t->if_id = x->if_id;
  95
  96         if (xfrm_init_state(t))
  97                 goto error;
  98
  99         atomic_set(&t->tunnel_users, 1);
 100
 101 out:
 102         return t;
 103
 104 error:
 105         t->km.state = XFRM_STATE_DEAD;
 106         xfrm_state_put(t);
 107         t = NULL;
 108         goto out;
 109 }
 110
 111 static int ipcomp6_tunnel_attach(struct xfrm_state *x)
 112 {
 113         struct net *net = xs_net(x);
 114         int err = 0;
 115         struct xfrm_state *t = NULL;
 116         __be32 spi;
 117         u32 mark = x->mark.m & x->mark.v;
 118
 119         spi = xfrm6_tunnel_spi_lookup(net, (xfrm_address_t *)&x->props.saddr);
 120         if (spi)
 121                 t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr,
 122                                               spi, IPPROTO_IPV6, AF_INET6);
 123         if (!t) {
 124                 t = ipcomp6_tunnel_create(x);
 125                 if (!t) {
 126                         err = -EINVAL;
 127                         goto out;
 128                 }
 129                 xfrm_state_insert(t);
 130                 xfrm_state_hold(t);
 131         }
 132         x->tunnel = t;
 133         atomic_inc(&t->tunnel_users);
 134
 135 out:
 136         return err;
 137 }
 138
 139 static int ipcomp6_init_state(struct xfrm_state *x,
 140                               struct netlink_ext_ack *extack)
 141 {
 142         int err = -EINVAL;
 143
 144         x->props.header_len = 0;
 145         switch (x->props.mode) {
 146         case XFRM_MODE_TRANSPORT:
 147                 break;
 148         case XFRM_MODE_TUNNEL:
 149                 x->props.header_len += sizeof(struct ipv6hdr);
 150                 break;
 151         default:
 152                 NL_SET_ERR_MSG(extack, "Unsupported XFRM mode for IPcomp");
 153                 goto out;
 154         }
 155
 156         err = ipcomp_init_state(x, extack);
 157         if (err)
 158                 goto out;
 159
 160         if (x->props.mode == XFRM_MODE_TUNNEL) {
 161                 err = ipcomp6_tunnel_attach(x);
 162                 if (err) {
 163                         NL_SET_ERR_MSG(extack, "Kernel error: failed to initialize the associated state");
 164                         goto out;
 165                 }
 166         }
 167
 168         err = 0;
 169 out:
 170         return err;
 171 }
 172
 173 static int ipcomp6_rcv_cb(struct sk_buff *skb, int err)
 174 {
 175         return 0;
 176 }
 177
 178 static const struct xfrm_type ipcomp6_type = {
 179         .owner          = THIS_MODULE,
 180         .proto          = IPPROTO_COMP,
 181         .init_state     = ipcomp6_init_state,
 182         .destructor     = ipcomp_destroy,
 183         .input          = ipcomp_input,
 184         .output         = ipcomp_output,
 185 };
 186
 187 static struct xfrm6_protocol ipcomp6_protocol = {
 188         .handler        = xfrm6_rcv,
 189         .input_handler  = xfrm_input,
 190         .cb_handler     = ipcomp6_rcv_cb,
 191         .err_handler    = ipcomp6_err,
 192         .priority       = 0,
 193 };
 194
 195 static int __init ipcomp6_init(void)
 196 {
 197         if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
 198                 pr_info("%s: can't add xfrm type\n", __func__);
 199                 return -EAGAIN;
 200         }
 201         if (xfrm6_protocol_register(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
 202                 pr_info("%s: can't add protocol\n", __func__);
 203                 xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 204                 return -EAGAIN;
 205         }
 206         return 0;
 207 }
 208
 209 static void __exit ipcomp6_fini(void)
 210 {
 211         if (xfrm6_protocol_deregister(&ipcomp6_protocol, IPPROTO_COMP) < 0)
 212                 pr_info("%s: can't remove protocol\n", __func__);
 213         xfrm_unregister_type(&ipcomp6_type, AF_INET6);
 214 }
 215
 216 module_init(ipcomp6_init);
 217 module_exit(ipcomp6_fini);
 218 MODULE_LICENSE("GPL");
 219 MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
 220 MODULE_AUTHOR("Mitsuru KANDA <mk@linux-ipv6.org>");
 221
 222 MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);