[PATCH] w1: Userspace communication protocol over connector.

[linux-2.6/verdex.git] / net / ipv6 / icmp.c

/*
 *      Internet Control Message Protocol (ICMPv6)
 *      Linux INET6 implementation
 *
 *      Authors:
 *      Pedro Roque             <roque@di.fc.ul.pt>
 *
 *      $Id: icmp.c,v 1.38 2002/02/08 03:57:19 davem Exp $
 *
 *      Based on net/ipv4/icmp.c
 *
 *      RFC 1885
 *
 *      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.
 */

/*
 *      Changes:
 *
 *      Andi Kleen              :       exception handling
 *      Andi Kleen                      add rate limits. never reply to a icmp.
 *                                      add more length checks and other fixes.
 *      yoshfuji                :       ensure to sent parameter problem for
 *                                      fragments.
 *      YOSHIFUJI Hideaki @USAGI:       added sysctl for icmp rate limit.
 *      Randy Dunlap and
 *      YOSHIFUJI Hideaki @USAGI:       Per-interface statistics support
 *      Kazunori MIYAZAWA @USAGI:       change output process to use ip6_append_data
 */

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/skbuff.h>
#include <linux/init.h>
#include <linux/netfilter.h>

#ifdef CONFIG_SYSCTL
#include <linux/sysctl.h>
#endif

#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/icmpv6.h>

#include <net/ip.h>
#include <net/sock.h>

#include <net/ipv6.h>
#include <net/ip6_checksum.h>
#include <net/protocol.h>
#include <net/raw.h>
#include <net/rawv6.h>
#include <net/transp_v6.h>
#include <net/ip6_route.h>
#include <net/addrconf.h>
#include <net/icmp.h>

#include <asm/uaccess.h>
#include <asm/system.h>

DEFINE_SNMP_STAT(struct icmpv6_mib, icmpv6_statistics) __read_mostly;

/*
 *      The ICMP socket(s). This is the most convenient way to flow control
 *      our ICMP output as well as maintain a clean interface throughout
 *      all layers. All Socketless IP sends will soon be gone.
 *
 *      On SMP we have one ICMP socket per-cpu.
 */
static DEFINE_PER_CPU(struct socket *, __icmpv6_socket) = NULL;
#define icmpv6_socket   __get_cpu_var(__icmpv6_socket)

static int icmpv6_rcv(struct sk_buff **pskb);

static struct inet6_protocol icmpv6_protocol = {
        .handler        =       icmpv6_rcv,
        .flags          =       INET6_PROTO_FINAL,
};

static __inline__ int icmpv6_xmit_lock(void)
{
        local_bh_disable();

        if (unlikely(!spin_trylock(&icmpv6_socket->sk->sk_lock.slock))) {
                /* This can happen if the output path (f.e. SIT or
                 * ip6ip6 tunnel) signals dst_link_failure() for an
                 * outgoing ICMP6 packet.
                 */
                local_bh_enable();
                return 1;
        }
        return 0;
}

static __inline__ void icmpv6_xmit_unlock(void)
{
        spin_unlock_bh(&icmpv6_socket->sk->sk_lock.slock);
}

/* 
 * Slightly more convenient version of icmpv6_send.
 */
void icmpv6_param_prob(struct sk_buff *skb, int code, int pos)
{
        icmpv6_send(skb, ICMPV6_PARAMPROB, code, pos, skb->dev);
        kfree_skb(skb);
}

/*
 * Figure out, may we reply to this packet with icmp error.
 *
 * We do not reply, if:
 *      - it was icmp error message.
 *      - it is truncated, so that it is known, that protocol is ICMPV6
 *        (i.e. in the middle of some exthdr)
 *
 *      --ANK (980726)
 */

static int is_ineligible(struct sk_buff *skb)
{
        int ptr = (u8*)(skb->nh.ipv6h+1) - skb->data;
        int len = skb->len - ptr;
        __u8 nexthdr = skb->nh.ipv6h->nexthdr;

        if (len < 0)
                return 1;

        ptr = ipv6_skip_exthdr(skb, ptr, &nexthdr);
        if (ptr < 0)
                return 0;
        if (nexthdr == IPPROTO_ICMPV6) {
                u8 _type, *tp;
                tp = skb_header_pointer(skb,
                        ptr+offsetof(struct icmp6hdr, icmp6_type),
                        sizeof(_type), &_type);
                if (tp == NULL ||
                    !(*tp & ICMPV6_INFOMSG_MASK))
                        return 1;
        }
        return 0;
}

static int sysctl_icmpv6_time = 1*HZ; 

/* 
 * Check the ICMP output rate limit 
 */
static inline int icmpv6_xrlim_allow(struct sock *sk, int type,
                                     struct flowi *fl)
{
        struct dst_entry *dst;
        int res = 0;

        /* Informational messages are not limited. */
        if (type & ICMPV6_INFOMSG_MASK)
                return 1;

        /* Do not limit pmtu discovery, it would break it. */
        if (type == ICMPV6_PKT_TOOBIG)
                return 1;

        /* 
         * Look up the output route.
         * XXX: perhaps the expire for routing entries cloned by
         * this lookup should be more aggressive (not longer than timeout).
         */
        dst = ip6_route_output(sk, fl);
        if (dst->error) {
                IP6_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
        } else if (dst->dev && (dst->dev->flags&IFF_LOOPBACK)) {
                res = 1;
        } else {
                struct rt6_info *rt = (struct rt6_info *)dst;
                int tmo = sysctl_icmpv6_time;

                /* Give more bandwidth to wider prefixes. */
                if (rt->rt6i_dst.plen < 128)
                        tmo >>= ((128 - rt->rt6i_dst.plen)>>5);

                res = xrlim_allow(dst, tmo);
        }
        dst_release(dst);
        return res;
}

/*
 *      an inline helper for the "simple" if statement below
 *      checks if parameter problem report is caused by an
 *      unrecognized IPv6 option that has the Option Type 
 *      highest-order two bits set to 10
 */

static __inline__ int opt_unrec(struct sk_buff *skb, __u32 offset)
{
        u8 _optval, *op;

        offset += skb->nh.raw - skb->data;
        op = skb_header_pointer(skb, offset, sizeof(_optval), &_optval);
        if (op == NULL)
                return 1;
        return (*op & 0xC0) == 0x80;
}

static int icmpv6_push_pending_frames(struct sock *sk, struct flowi *fl, struct icmp6hdr *thdr, int len)
{
        struct sk_buff *skb;
        struct icmp6hdr *icmp6h;
        int err = 0;

        if ((skb = skb_peek(&sk->sk_write_queue)) == NULL)
                goto out;

        icmp6h = (struct icmp6hdr*) skb->h.raw;
        memcpy(icmp6h, thdr, sizeof(struct icmp6hdr));
        icmp6h->icmp6_cksum = 0;

        if (skb_queue_len(&sk->sk_write_queue) == 1) {
                skb->csum = csum_partial((char *)icmp6h,
                                        sizeof(struct icmp6hdr), skb->csum);
                icmp6h->icmp6_cksum = csum_ipv6_magic(&fl->fl6_src,
                                                      &fl->fl6_dst,
                                                      len, fl->proto,
                                                      skb->csum);
        } else {
                u32 tmp_csum = 0;

                skb_queue_walk(&sk->sk_write_queue, skb) {
                        tmp_csum = csum_add(tmp_csum, skb->csum);
                }

                tmp_csum = csum_partial((char *)icmp6h,
                                        sizeof(struct icmp6hdr), tmp_csum);
                tmp_csum = csum_ipv6_magic(&fl->fl6_src,
                                           &fl->fl6_dst,
                                           len, fl->proto, tmp_csum);
                icmp6h->icmp6_cksum = tmp_csum;
        }
        if (icmp6h->icmp6_cksum == 0)
                icmp6h->icmp6_cksum = -1;
        ip6_push_pending_frames(sk);
out:
        return err;
}

struct icmpv6_msg {
        struct sk_buff  *skb;
        int             offset;
        uint8_t         type;
};

static int icmpv6_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb)
{
        struct icmpv6_msg *msg = (struct icmpv6_msg *) from;
        struct sk_buff *org_skb = msg->skb;
        __u32 csum = 0;

        csum = skb_copy_and_csum_bits(org_skb, msg->offset + offset,
                                      to, len, csum);
        skb->csum = csum_block_add(skb->csum, csum, odd);
        if (!(msg->type & ICMPV6_INFOMSG_MASK))
                nf_ct_attach(skb, org_skb);
        return 0;
}

/*
 *      Send an ICMP message in response to a packet in error
 */
void icmpv6_send(struct sk_buff *skb, int type, int code, __u32 info, 
                 struct net_device *dev)
{
        struct inet6_dev *idev = NULL;
        struct ipv6hdr *hdr = skb->nh.ipv6h;
        struct sock *sk;
        struct ipv6_pinfo *np;
        struct in6_addr *saddr = NULL;
        struct dst_entry *dst;
        struct icmp6hdr tmp_hdr;
        struct flowi fl;
        struct icmpv6_msg msg;
        int iif = 0;
        int addr_type = 0;
        int len;
        int hlimit, tclass;
        int err = 0;

        if ((u8*)hdr < skb->head || (u8*)(hdr+1) > skb->tail)
                return;

        /*
         *      Make sure we respect the rules 
         *      i.e. RFC 1885 2.4(e)
         *      Rule (e.1) is enforced by not using icmpv6_send
         *      in any code that processes icmp errors.
         */
        addr_type = ipv6_addr_type(&hdr->daddr);

        if (ipv6_chk_addr(&hdr->daddr, skb->dev, 0))
                saddr = &hdr->daddr;

        /*
         *      Dest addr check
         */

        if ((addr_type & IPV6_ADDR_MULTICAST || skb->pkt_type != PACKET_HOST)) {
                if (type != ICMPV6_PKT_TOOBIG &&
                    !(type == ICMPV6_PARAMPROB && 
                      code == ICMPV6_UNK_OPTION && 
                      (opt_unrec(skb, info))))
                        return;

                saddr = NULL;
        }

        addr_type = ipv6_addr_type(&hdr->saddr);

        /*
         *      Source addr check
         */

        if (addr_type & IPV6_ADDR_LINKLOCAL)
                iif = skb->dev->ifindex;

        /*
         *      Must not send error if the source does not uniquely
         *      identify a single node (RFC2463 Section 2.4).
         *      We check unspecified / multicast addresses here,
         *      and anycast addresses will be checked later.
         */
        if ((addr_type == IPV6_ADDR_ANY) || (addr_type & IPV6_ADDR_MULTICAST)) {
                LIMIT_NETDEBUG(KERN_DEBUG "icmpv6_send: addr_any/mcast source\n");
                return;
        }

        /* 
         *      Never answer to a ICMP packet.
         */
        if (is_ineligible(skb)) {
                LIMIT_NETDEBUG(KERN_DEBUG "icmpv6_send: no reply to icmp error\n");
                return;
        }

        memset(&fl, 0, sizeof(fl));
        fl.proto = IPPROTO_ICMPV6;
        ipv6_addr_copy(&fl.fl6_dst, &hdr->saddr);
        if (saddr)
                ipv6_addr_copy(&fl.fl6_src, saddr);
        fl.oif = iif;
        fl.fl_icmp_type = type;
        fl.fl_icmp_code = code;

        if (icmpv6_xmit_lock())
                return;

        sk = icmpv6_socket->sk;
        np = inet6_sk(sk);

        if (!icmpv6_xrlim_allow(sk, type, &fl))
                goto out;

        tmp_hdr.icmp6_type = type;
        tmp_hdr.icmp6_code = code;
        tmp_hdr.icmp6_cksum = 0;
        tmp_hdr.icmp6_pointer = htonl(info);

        if (!fl.oif && ipv6_addr_is_multicast(&fl.fl6_dst))
                fl.oif = np->mcast_oif;

        err = ip6_dst_lookup(sk, &dst, &fl);
        if (err)
                goto out;

        /*
         * We won't send icmp if the destination is known
         * anycast.
         */
        if (((struct rt6_info *)dst)->rt6i_flags & RTF_ANYCAST) {
                LIMIT_NETDEBUG(KERN_DEBUG "icmpv6_send: acast source\n");
                goto out_dst_release;
        }

        if ((err = xfrm_lookup(&dst, &fl, sk, 0)) < 0)
                goto out;

        if (ipv6_addr_is_multicast(&fl.fl6_dst))
                hlimit = np->mcast_hops;
        else
                hlimit = np->hop_limit;
        if (hlimit < 0)
                hlimit = dst_metric(dst, RTAX_HOPLIMIT);
        if (hlimit < 0)
                hlimit = ipv6_get_hoplimit(dst->dev);

        tclass = np->cork.tclass;
        if (tclass < 0)
                tclass = 0;

        msg.skb = skb;
        msg.offset = skb->nh.raw - skb->data;
        msg.type = type;

        len = skb->len - msg.offset;
        len = min_t(unsigned int, len, IPV6_MIN_MTU - sizeof(struct ipv6hdr) -sizeof(struct icmp6hdr));
        if (len < 0) {
                LIMIT_NETDEBUG(KERN_DEBUG "icmp: len problem\n");
                goto out_dst_release;
        }

        idev = in6_dev_get(skb->dev);

        err = ip6_append_data(sk, icmpv6_getfrag, &msg,
                              len + sizeof(struct icmp6hdr),
                              sizeof(struct icmp6hdr),
                              hlimit, tclass, NULL, &fl, (struct rt6_info*)dst,
                              MSG_DONTWAIT);
        if (err) {
                ip6_flush_pending_frames(sk);
                goto out_put;
        }
        err = icmpv6_push_pending_frames(sk, &fl, &tmp_hdr, len + sizeof(struct icmp6hdr));

        if (type >= ICMPV6_DEST_UNREACH && type <= ICMPV6_PARAMPROB)
                ICMP6_INC_STATS_OFFSET_BH(idev, ICMP6_MIB_OUTDESTUNREACHS, type - ICMPV6_DEST_UNREACH);
        ICMP6_INC_STATS_BH(idev, ICMP6_MIB_OUTMSGS);

out_put:
        if (likely(idev != NULL))
                in6_dev_put(idev);
out_dst_release:
        dst_release(dst);
out:
        icmpv6_xmit_unlock();
}

static void icmpv6_echo_reply(struct sk_buff *skb)
{
        struct sock *sk;
        struct inet6_dev *idev;
        struct ipv6_pinfo *np;
        struct in6_addr *saddr = NULL;
        struct icmp6hdr *icmph = (struct icmp6hdr *) skb->h.raw;
        struct icmp6hdr tmp_hdr;
        struct flowi fl;
        struct icmpv6_msg msg;
        struct dst_entry *dst;
        int err = 0;
        int hlimit;
        int tclass;

        saddr = &skb->nh.ipv6h->daddr;

        if (!ipv6_unicast_destination(skb))
                saddr = NULL;

        memcpy(&tmp_hdr, icmph, sizeof(tmp_hdr));
        tmp_hdr.icmp6_type = ICMPV6_ECHO_REPLY;

        memset(&fl, 0, sizeof(fl));
        fl.proto = IPPROTO_ICMPV6;
        ipv6_addr_copy(&fl.fl6_dst, &skb->nh.ipv6h->saddr);
        if (saddr)
                ipv6_addr_copy(&fl.fl6_src, saddr);
        fl.oif = skb->dev->ifindex;
        fl.fl_icmp_type = ICMPV6_ECHO_REPLY;

        if (icmpv6_xmit_lock())
                return;

        sk = icmpv6_socket->sk;
        np = inet6_sk(sk);

        if (!fl.oif && ipv6_addr_is_multicast(&fl.fl6_dst))
                fl.oif = np->mcast_oif;

        err = ip6_dst_lookup(sk, &dst, &fl);
        if (err)
                goto out;
        if ((err = xfrm_lookup(&dst, &fl, sk, 0)) < 0)
                goto out;

        if (ipv6_addr_is_multicast(&fl.fl6_dst))
                hlimit = np->mcast_hops;
        else
                hlimit = np->hop_limit;
        if (hlimit < 0)
                hlimit = dst_metric(dst, RTAX_HOPLIMIT);
        if (hlimit < 0)
                hlimit = ipv6_get_hoplimit(dst->dev);

        tclass = np->cork.tclass;
        if (tclass < 0)
                tclass = 0;

        idev = in6_dev_get(skb->dev);

        msg.skb = skb;
        msg.offset = 0;
        msg.type = ICMPV6_ECHO_REPLY;

        err = ip6_append_data(sk, icmpv6_getfrag, &msg, skb->len + sizeof(struct icmp6hdr),
                                sizeof(struct icmp6hdr), hlimit, tclass, NULL, &fl,
                                (struct rt6_info*)dst, MSG_DONTWAIT);

        if (err) {
                ip6_flush_pending_frames(sk);
                goto out_put;
        }
        err = icmpv6_push_pending_frames(sk, &fl, &tmp_hdr, skb->len + sizeof(struct icmp6hdr));

        ICMP6_INC_STATS_BH(idev, ICMP6_MIB_OUTECHOREPLIES);
        ICMP6_INC_STATS_BH(idev, ICMP6_MIB_OUTMSGS);

out_put: 
        if (likely(idev != NULL))
                in6_dev_put(idev);
        dst_release(dst);
out: 
        icmpv6_xmit_unlock();
}

static void icmpv6_notify(struct sk_buff *skb, int type, int code, u32 info)
{
        struct in6_addr *saddr, *daddr;
        struct inet6_protocol *ipprot;
        struct sock *sk;
        int inner_offset;
        int hash;
        u8 nexthdr;

        if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
                return;

        nexthdr = ((struct ipv6hdr *)skb->data)->nexthdr;
        if (ipv6_ext_hdr(nexthdr)) {
                /* now skip over extension headers */
                inner_offset = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr), &nexthdr);
                if (inner_offset<0)
                        return;
        } else {
                inner_offset = sizeof(struct ipv6hdr);
        }

        /* Checkin header including 8 bytes of inner protocol header. */
        if (!pskb_may_pull(skb, inner_offset+8))
                return;

        saddr = &skb->nh.ipv6h->saddr;
        daddr = &skb->nh.ipv6h->daddr;

        /* BUGGG_FUTURE: we should try to parse exthdrs in this packet.
           Without this we will not able f.e. to make source routed
           pmtu discovery.
           Corresponding argument (opt) to notifiers is already added.
           --ANK (980726)
         */

        hash = nexthdr & (MAX_INET_PROTOS - 1);

        rcu_read_lock();
        ipprot = rcu_dereference(inet6_protos[hash]);
        if (ipprot && ipprot->err_handler)
                ipprot->err_handler(skb, NULL, type, code, inner_offset, info);
        rcu_read_unlock();

        read_lock(&raw_v6_lock);
        if ((sk = sk_head(&raw_v6_htable[hash])) != NULL) {
                while((sk = __raw_v6_lookup(sk, nexthdr, daddr, saddr,
                                            IP6CB(skb)->iif))) {
                        rawv6_err(sk, skb, NULL, type, code, inner_offset, info);
                        sk = sk_next(sk);
                }
        }
        read_unlock(&raw_v6_lock);
}
  
/*
 *      Handle icmp messages
 */

static int icmpv6_rcv(struct sk_buff **pskb)
{
        struct sk_buff *skb = *pskb;
        struct net_device *dev = skb->dev;
        struct inet6_dev *idev = __in6_dev_get(dev);
        struct in6_addr *saddr, *daddr;
        struct ipv6hdr *orig_hdr;
        struct icmp6hdr *hdr;
        int type;

        ICMP6_INC_STATS_BH(idev, ICMP6_MIB_INMSGS);

        saddr = &skb->nh.ipv6h->saddr;
        daddr = &skb->nh.ipv6h->daddr;

        /* Perform checksum. */
        switch (skb->ip_summed) {
        case CHECKSUM_HW:
                if (!csum_ipv6_magic(saddr, daddr, skb->len, IPPROTO_ICMPV6,
                                     skb->csum))
                        break;
                /* fall through */
        case CHECKSUM_NONE:
                skb->csum = ~csum_ipv6_magic(saddr, daddr, skb->len,
                                             IPPROTO_ICMPV6, 0);
                if (__skb_checksum_complete(skb)) {
                        LIMIT_NETDEBUG(KERN_DEBUG "ICMPv6 checksum failed [" NIP6_FMT " > " NIP6_FMT "]\n",
                                       NIP6(*saddr), NIP6(*daddr));
                        goto discard_it;
                }
        }

        if (!pskb_pull(skb, sizeof(struct icmp6hdr)))
                goto discard_it;

        hdr = (struct icmp6hdr *) skb->h.raw;

        type = hdr->icmp6_type;

        if (type >= ICMPV6_DEST_UNREACH && type <= ICMPV6_PARAMPROB)
                ICMP6_INC_STATS_OFFSET_BH(idev, ICMP6_MIB_INDESTUNREACHS, type - ICMPV6_DEST_UNREACH);
        else if (type >= ICMPV6_ECHO_REQUEST && type <= NDISC_REDIRECT)
                ICMP6_INC_STATS_OFFSET_BH(idev, ICMP6_MIB_INECHOS, type - ICMPV6_ECHO_REQUEST);

        switch (type) {
        case ICMPV6_ECHO_REQUEST:
                icmpv6_echo_reply(skb);
                break;

        case ICMPV6_ECHO_REPLY:
                /* we couldn't care less */
                break;

        case ICMPV6_PKT_TOOBIG:
                /* BUGGG_FUTURE: if packet contains rthdr, we cannot update
                   standard destination cache. Seems, only "advanced"
                   destination cache will allow to solve this problem
                   --ANK (980726)
                 */
                if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
                        goto discard_it;
                hdr = (struct icmp6hdr *) skb->h.raw;
                orig_hdr = (struct ipv6hdr *) (hdr + 1);
                rt6_pmtu_discovery(&orig_hdr->daddr, &orig_hdr->saddr, dev,
                                   ntohl(hdr->icmp6_mtu));

                /*
                 *      Drop through to notify
                 */

        case ICMPV6_DEST_UNREACH:
        case ICMPV6_TIME_EXCEED:
        case ICMPV6_PARAMPROB:
                icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);
                break;

        case NDISC_ROUTER_SOLICITATION:
        case NDISC_ROUTER_ADVERTISEMENT:
        case NDISC_NEIGHBOUR_SOLICITATION:
        case NDISC_NEIGHBOUR_ADVERTISEMENT:
        case NDISC_REDIRECT:
                ndisc_rcv(skb);
                break;

        case ICMPV6_MGM_QUERY:
                igmp6_event_query(skb);
                break;

        case ICMPV6_MGM_REPORT:
                igmp6_event_report(skb);
                break;

        case ICMPV6_MGM_REDUCTION:
        case ICMPV6_NI_QUERY:
        case ICMPV6_NI_REPLY:
        case ICMPV6_MLD2_REPORT:
        case ICMPV6_DHAAD_REQUEST:
        case ICMPV6_DHAAD_REPLY:
        case ICMPV6_MOBILE_PREFIX_SOL:
        case ICMPV6_MOBILE_PREFIX_ADV:
                break;

        default:
                LIMIT_NETDEBUG(KERN_DEBUG "icmpv6: msg of unknown type\n");

                /* informational */
                if (type & ICMPV6_INFOMSG_MASK)
                        break;

                /* 
                 * error of unknown type. 
                 * must pass to upper level 
                 */

                icmpv6_notify(skb, type, hdr->icmp6_code, hdr->icmp6_mtu);
        };
        kfree_skb(skb);
        return 0;

discard_it:
        ICMP6_INC_STATS_BH(idev, ICMP6_MIB_INERRORS);
        kfree_skb(skb);
        return 0;
}

int __init icmpv6_init(struct net_proto_family *ops)
{
        struct sock *sk;
        int err, i, j;

        for_each_possible_cpu(i) {
                err = sock_create_kern(PF_INET6, SOCK_RAW, IPPROTO_ICMPV6,
                                       &per_cpu(__icmpv6_socket, i));
                if (err < 0) {
                        printk(KERN_ERR
                               "Failed to initialize the ICMP6 control socket "
                               "(err %d).\n",
                               err);
                        goto fail;
                }

                sk = per_cpu(__icmpv6_socket, i)->sk;
                sk->sk_allocation = GFP_ATOMIC;

                /* Enough space for 2 64K ICMP packets, including
                 * sk_buff struct overhead.
                 */
                sk->sk_sndbuf =
                        (2 * ((64 * 1024) + sizeof(struct sk_buff)));

                sk->sk_prot->unhash(sk);
        }


        if (inet6_add_protocol(&icmpv6_protocol, IPPROTO_ICMPV6) < 0) {
                printk(KERN_ERR "Failed to register ICMP6 protocol\n");
                err = -EAGAIN;
                goto fail;
        }

        return 0;

 fail:
        for (j = 0; j < i; j++) {
                if (!cpu_possible(j))
                        continue;
                sock_release(per_cpu(__icmpv6_socket, j));
        }

        return err;
}

void icmpv6_cleanup(void)
{
        int i;

        for_each_possible_cpu(i) {
                sock_release(per_cpu(__icmpv6_socket, i));
        }
        inet6_del_protocol(&icmpv6_protocol, IPPROTO_ICMPV6);
}

static const struct icmp6_err {
        int err;
        int fatal;
} tab_unreach[] = {
        {       /* NOROUTE */
                .err    = ENETUNREACH,
                .fatal  = 0,
        },
        {       /* ADM_PROHIBITED */
                .err    = EACCES,
                .fatal  = 1,
        },
        {       /* Was NOT_NEIGHBOUR, now reserved */
                .err    = EHOSTUNREACH,
                .fatal  = 0,
        },
        {       /* ADDR_UNREACH */
                .err    = EHOSTUNREACH,
                .fatal  = 0,
        },
        {       /* PORT_UNREACH */
                .err    = ECONNREFUSED,
                .fatal  = 1,
        },
};

int icmpv6_err_convert(int type, int code, int *err)
{
        int fatal = 0;

        *err = EPROTO;

        switch (type) {
        case ICMPV6_DEST_UNREACH:
                fatal = 1;
                if (code <= ICMPV6_PORT_UNREACH) {
                        *err  = tab_unreach[code].err;
                        fatal = tab_unreach[code].fatal;
                }
                break;

        case ICMPV6_PKT_TOOBIG:
                *err = EMSGSIZE;
                break;
                
        case ICMPV6_PARAMPROB:
                *err = EPROTO;
                fatal = 1;
                break;

        case ICMPV6_TIME_EXCEED:
                *err = EHOSTUNREACH;
                break;
        };

        return fatal;
}

#ifdef CONFIG_SYSCTL
ctl_table ipv6_icmp_table[] = {
        {
                .ctl_name       = NET_IPV6_ICMP_RATELIMIT,
                .procname       = "ratelimit",
                .data           = &sysctl_icmpv6_time,
                .maxlen         = sizeof(int),
                .mode           = 0644,
                .proc_handler   = &proc_dointvec
        },
        { .ctl_name = 0 },
};
#endif