ipcomp6.c

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/*
 * IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173
 *
 * Copyright (C)2003 USAGI/WIDE Project
 *
 * Author   Mitsuru KANDA  <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
/*
 * [Memo]
 *
 * Outbound:
 *  The compression of IP datagram MUST be done before AH/ESP processing,
 *  fragmentation, and the addition of Hop-by-Hop/Routing header.
 *
 * Inbound:
 *  The decompression of IP datagram MUST be done after the reassembly,
 *  AH/ESP processing.
 */

#define pr_fmt(fmt) "IPv6: " fmt

#include <linux/module.h>
#include <net/ip.h>
#include <net/xfrm.h>
#include <net/ipcomp.h>
#include <linux/crypto.h>
#include <linux/err.h>
#include <linux/pfkeyv2.h>
#include <linux/random.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/list.h>
#include <linux/vmalloc.h>
#include <linux/rtnetlink.h>
#include <net/ip6_route.h>
#include <net/icmp.h>
#include <net/ipv6.h>
#include <net/protocol.h>
#include <linux/ipv6.h>
#include <linux/icmpv6.h>
#include <linux/mutex.h>

static void ipcomp6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                u8 type, u8 code, int offset, __be32 info)
{
    struct net *net = dev_net(skb->dev);
    __be32 spi;
    const struct ipv6hdr *iph = (const struct ipv6hdr *)skb->data;
    struct ip_comp_hdr *ipcomph =
        (struct ip_comp_hdr *)(skb->data + offset);
    struct xfrm_state *x;

    if (type != ICMPV6_DEST_UNREACH &&
        type != ICMPV6_PKT_TOOBIG &&
        type != NDISC_REDIRECT)
        return;

    spi = htonl(ntohs(ipcomph->cpi));
    x = xfrm_state_lookup(net, skb->mark, (const xfrm_address_t *)&iph->daddr,
                  spi, IPPROTO_COMP, AF_INET6);
    if (!x)
        return;

    if (type == NDISC_REDIRECT)
        ip6_redirect(skb, net, 0, 0);
    else
        ip6_update_pmtu(skb, net, info, 0, 0);
    xfrm_state_put(x);
}

static struct xfrm_state *ipcomp6_tunnel_create(struct xfrm_state *x)
{
    struct net *net = xs_net(x);
    struct xfrm_state *t = NULL;

    t = xfrm_state_alloc(net);
    if (!t)
        goto out;

    t->id.proto = IPPROTO_IPV6;
    t->id.spi = xfrm6_tunnel_alloc_spi(net, (xfrm_address_t *)&x->props.saddr);
    if (!t->id.spi)
        goto error;

    memcpy(t->id.daddr.a6, x->id.daddr.a6, sizeof(struct in6_addr));
    memcpy(&t->sel, &x->sel, sizeof(t->sel));
    t->props.family = AF_INET6;
    t->props.mode = x->props.mode;
    memcpy(t->props.saddr.a6, x->props.saddr.a6, sizeof(struct in6_addr));
    memcpy(&t->mark, &x->mark, sizeof(t->mark));

    if (xfrm_init_state(t))
        goto error;

    atomic_set(&t->tunnel_users, 1);

out:
    return t;

error:
    t->km.state = XFRM_STATE_DEAD;
    xfrm_state_put(t);
    t = NULL;
    goto out;
}

static int ipcomp6_tunnel_attach(struct xfrm_state *x)
{
    struct net *net = xs_net(x);
    int err = 0;
    struct xfrm_state *t = NULL;
    __be32 spi;
    u32 mark = x->mark.m & x->mark.v;

    spi = xfrm6_tunnel_spi_lookup(net, (xfrm_address_t *)&x->props.saddr);
    if (spi)
        t = xfrm_state_lookup(net, mark, (xfrm_address_t *)&x->id.daddr,
                          spi, IPPROTO_IPV6, AF_INET6);
    if (!t) {
        t = ipcomp6_tunnel_create(x);
        if (!t) {
            err = -EINVAL;
            goto out;
        }
        xfrm_state_insert(t);
        xfrm_state_hold(t);
    }
    x->tunnel = t;
    atomic_inc(&t->tunnel_users);

out:
    return err;
}

static int ipcomp6_init_state(struct xfrm_state *x)
{
    int err = -EINVAL;

    x->props.header_len = 0;
    switch (x->props.mode) {
    case XFRM_MODE_TRANSPORT:
        break;
    case XFRM_MODE_TUNNEL:
        x->props.header_len += sizeof(struct ipv6hdr);
        break;
    default:
        goto out;
    }

    err = ipcomp_init_state(x);
    if (err)
        goto out;

    if (x->props.mode == XFRM_MODE_TUNNEL) {
        err = ipcomp6_tunnel_attach(x);
        if (err)
            goto out;
    }

    err = 0;
out:
    return err;
}

static const struct xfrm_type ipcomp6_type =
{
    .description    = "IPCOMP6",
    .owner      = THIS_MODULE,
    .proto      = IPPROTO_COMP,
    .init_state = ipcomp6_init_state,
    .destructor = ipcomp_destroy,
    .input      = ipcomp_input,
    .output     = ipcomp_output,
    .hdr_offset = xfrm6_find_1stfragopt,
};

static const struct inet6_protocol ipcomp6_protocol =
{
    .handler    = xfrm6_rcv,
    .err_handler    = ipcomp6_err,
    .flags      = INET6_PROTO_NOPOLICY,
};

static int __init ipcomp6_init(void)
{
    if (xfrm_register_type(&ipcomp6_type, AF_INET6) < 0) {
        pr_info("%s: can't add xfrm type\n", __func__);
        return -EAGAIN;
    }
    if (inet6_add_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0) {
        pr_info("%s: can't add protocol\n", __func__);
        xfrm_unregister_type(&ipcomp6_type, AF_INET6);
        return -EAGAIN;
    }
    return 0;
}

static void __exit ipcomp6_fini(void)
{
    if (inet6_del_protocol(&ipcomp6_protocol, IPPROTO_COMP) < 0)
        pr_info("%s: can't remove protocol\n", __func__);
    if (xfrm_unregister_type(&ipcomp6_type, AF_INET6) < 0)
        pr_info("%s: can't remove xfrm type\n", __func__);
}

module_init(ipcomp6_init);
module_exit(ipcomp6_fini);
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("IP Payload Compression Protocol (IPComp) for IPv6 - RFC3173");
MODULE_AUTHOR("Mitsuru KANDA <[email protected]>");

MODULE_ALIAS_XFRM_TYPE(AF_INET6, XFRM_PROTO_COMP);