tunnel6.c

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/*
 * Copyright (C)2003,2004 USAGI/WIDE Project
 *
 * 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
 *
 * Authors  Mitsuru KANDA  <[email protected]>
 *      YOSHIFUJI Hideaki <[email protected]>
 */

#define pr_fmt(fmt) "IPv6: " fmt

#include <linux/icmpv6.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <net/ipv6.h>
#include <net/protocol.h>
#include <net/xfrm.h>

static struct xfrm6_tunnel __rcu *tunnel6_handlers __read_mostly;
static struct xfrm6_tunnel __rcu *tunnel46_handlers __read_mostly;
static DEFINE_MUTEX(tunnel6_mutex);

int xfrm6_tunnel_register(struct xfrm6_tunnel *handler, unsigned short family)
{
    struct xfrm6_tunnel __rcu **pprev;
    struct xfrm6_tunnel *t;
    int ret = -EEXIST;
    int priority = handler->priority;

    mutex_lock(&tunnel6_mutex);

    for (pprev = (family == AF_INET6) ? &tunnel6_handlers : &tunnel46_handlers;
         (t = rcu_dereference_protected(*pprev,
            lockdep_is_held(&tunnel6_mutex))) != NULL;
         pprev = &t->next) {
        if (t->priority > priority)
            break;
        if (t->priority == priority)
            goto err;
    }

    handler->next = *pprev;
    rcu_assign_pointer(*pprev, handler);

    ret = 0;

err:
    mutex_unlock(&tunnel6_mutex);

    return ret;
}

EXPORT_SYMBOL(xfrm6_tunnel_register);

int xfrm6_tunnel_deregister(struct xfrm6_tunnel *handler, unsigned short family)
{
    struct xfrm6_tunnel __rcu **pprev;
    struct xfrm6_tunnel *t;
    int ret = -ENOENT;

    mutex_lock(&tunnel6_mutex);

    for (pprev = (family == AF_INET6) ? &tunnel6_handlers : &tunnel46_handlers;
         (t = rcu_dereference_protected(*pprev,
            lockdep_is_held(&tunnel6_mutex))) != NULL;
         pprev = &t->next) {
        if (t == handler) {
            *pprev = handler->next;
            ret = 0;
            break;
        }
    }

    mutex_unlock(&tunnel6_mutex);

    synchronize_net();

    return ret;
}

EXPORT_SYMBOL(xfrm6_tunnel_deregister);

#define for_each_tunnel_rcu(head, handler)      \
    for (handler = rcu_dereference(head);       \
         handler != NULL;               \
         handler = rcu_dereference(handler->next))  \

static int tunnel6_rcv(struct sk_buff *skb)
{
    struct xfrm6_tunnel *handler;

    if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
        goto drop;

    for_each_tunnel_rcu(tunnel6_handlers, handler)
        if (!handler->handler(skb))
            return 0;

    icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);

drop:
    kfree_skb(skb);
    return 0;
}

static int tunnel46_rcv(struct sk_buff *skb)
{
    struct xfrm6_tunnel *handler;

    if (!pskb_may_pull(skb, sizeof(struct iphdr)))
        goto drop;

    for_each_tunnel_rcu(tunnel46_handlers, handler)
        if (!handler->handler(skb))
            return 0;

    icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_PORT_UNREACH, 0);

drop:
    kfree_skb(skb);
    return 0;
}

static void tunnel6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
            u8 type, u8 code, int offset, __be32 info)
{
    struct xfrm6_tunnel *handler;

    for_each_tunnel_rcu(tunnel6_handlers, handler)
        if (!handler->err_handler(skb, opt, type, code, offset, info))
            break;
}

static const struct inet6_protocol tunnel6_protocol = {
    .handler    = tunnel6_rcv,
    .err_handler    = tunnel6_err,
    .flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
};

static const struct inet6_protocol tunnel46_protocol = {
    .handler    = tunnel46_rcv,
    .err_handler    = tunnel6_err,
    .flags          = INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
};

static int __init tunnel6_init(void)
{
    if (inet6_add_protocol(&tunnel6_protocol, IPPROTO_IPV6)) {
        pr_err("%s: can't add protocol\n", __func__);
        return -EAGAIN;
    }
    if (inet6_add_protocol(&tunnel46_protocol, IPPROTO_IPIP)) {
        pr_err("%s: can't add protocol\n", __func__);
        inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6);
        return -EAGAIN;
    }
    return 0;
}

static void __exit tunnel6_fini(void)
{
    if (inet6_del_protocol(&tunnel46_protocol, IPPROTO_IPIP))
        pr_err("%s: can't remove protocol\n", __func__);
    if (inet6_del_protocol(&tunnel6_protocol, IPPROTO_IPV6))
        pr_err("%s: can't remove protocol\n", __func__);
}

module_init(tunnel6_init);
module_exit(tunnel6_fini);
MODULE_LICENSE("GPL");