protocol.c

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/* SCTP kernel implementation
 * (C) Copyright IBM Corp. 2001, 2004
 * Copyright (c) 1999-2000 Cisco, Inc.
 * Copyright (c) 1999-2001 Motorola, Inc.
 * Copyright (c) 2001 Intel Corp.
 * Copyright (c) 2001 Nokia, Inc.
 * Copyright (c) 2001 La Monte H.P. Yarroll
 *
 * This file is part of the SCTP kernel implementation
 *
 * Initialization/cleanup for SCTP protocol support.
 *
 * This SCTP implementation 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, or (at your option)
 * any later version.
 *
 * This SCTP implementation 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 GNU CC; see the file COPYING.  If not, write to
 * the Free Software Foundation, 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <[email protected]>
 *
 * Or submit a bug report through the following website:
 *    http://www.sf.net/projects/lksctp
 *
 * Written or modified by:
 *    La Monte H.P. Yarroll <[email protected]>
 *    Karl Knutson <[email protected]>
 *    Jon Grimm <[email protected]>
 *    Sridhar Samudrala <[email protected]>
 *    Daisy Chang <[email protected]>
 *    Ardelle Fan <[email protected]>
 *
 * Any bugs reported given to us we will try to fix... any fixes shared will
 * be incorporated into the next SCTP release.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/init.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/seq_file.h>
#include <linux/bootmem.h>
#include <linux/highmem.h>
#include <linux/swap.h>
#include <linux/slab.h>
#include <net/net_namespace.h>
#include <net/protocol.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/route.h>
#include <net/sctp/sctp.h>
#include <net/addrconf.h>
#include <net/inet_common.h>
#include <net/inet_ecn.h>

/* Global data structures. */
struct sctp_globals sctp_globals __read_mostly;

struct idr sctp_assocs_id;
DEFINE_SPINLOCK(sctp_assocs_id_lock);

static struct sctp_pf *sctp_pf_inet6_specific;
static struct sctp_pf *sctp_pf_inet_specific;
static struct sctp_af *sctp_af_v4_specific;
static struct sctp_af *sctp_af_v6_specific;

struct kmem_cache *sctp_chunk_cachep __read_mostly;
struct kmem_cache *sctp_bucket_cachep __read_mostly;

long sysctl_sctp_mem[3];
int sysctl_sctp_rmem[3];
int sysctl_sctp_wmem[3];

/* Set up the proc fs entry for the SCTP protocol. */
static __net_init int sctp_proc_init(struct net *net)
{
#ifdef CONFIG_PROC_FS
    net->sctp.proc_net_sctp = proc_net_mkdir(net, "sctp", net->proc_net);
    if (!net->sctp.proc_net_sctp)
        goto out_proc_net_sctp;
    if (sctp_snmp_proc_init(net))
        goto out_snmp_proc_init;
    if (sctp_eps_proc_init(net))
        goto out_eps_proc_init;
    if (sctp_assocs_proc_init(net))
        goto out_assocs_proc_init;
    if (sctp_remaddr_proc_init(net))
        goto out_remaddr_proc_init;

    return 0;

out_remaddr_proc_init:
    sctp_assocs_proc_exit(net);
out_assocs_proc_init:
    sctp_eps_proc_exit(net);
out_eps_proc_init:
    sctp_snmp_proc_exit(net);
out_snmp_proc_init:
    remove_proc_entry("sctp", net->proc_net);
    net->sctp.proc_net_sctp = NULL;
out_proc_net_sctp:
    return -ENOMEM;
#endif /* CONFIG_PROC_FS */
    return 0;
}

/* Clean up the proc fs entry for the SCTP protocol.
 * Note: Do not make this __exit as it is used in the init error
 * path.
 */
static void sctp_proc_exit(struct net *net)
{
#ifdef CONFIG_PROC_FS
    sctp_snmp_proc_exit(net);
    sctp_eps_proc_exit(net);
    sctp_assocs_proc_exit(net);
    sctp_remaddr_proc_exit(net);

    remove_proc_entry("sctp", net->proc_net);
    net->sctp.proc_net_sctp = NULL;
#endif
}

/* Private helper to extract ipv4 address and stash them in
 * the protocol structure.
 */
static void sctp_v4_copy_addrlist(struct list_head *addrlist,
                  struct net_device *dev)
{
    struct in_device *in_dev;
    struct in_ifaddr *ifa;
    struct sctp_sockaddr_entry *addr;

    rcu_read_lock();
    if ((in_dev = __in_dev_get_rcu(dev)) == NULL) {
        rcu_read_unlock();
        return;
    }

    for (ifa = in_dev->ifa_list; ifa; ifa = ifa->ifa_next) {
        /* Add the address to the local list.  */
        addr = t_new(struct sctp_sockaddr_entry, GFP_ATOMIC);
        if (addr) {
            addr->a.v4.sin_family = AF_INET;
            addr->a.v4.sin_port = 0;
            addr->a.v4.sin_addr.s_addr = ifa->ifa_local;
            addr->valid = 1;
            INIT_LIST_HEAD(&addr->list);
            list_add_tail(&addr->list, addrlist);
        }
    }

    rcu_read_unlock();
}

/* Extract our IP addresses from the system and stash them in the
 * protocol structure.
 */
static void sctp_get_local_addr_list(struct net *net)
{
    struct net_device *dev;
    struct list_head *pos;
    struct sctp_af *af;

    rcu_read_lock();
    for_each_netdev_rcu(net, dev) {
        __list_for_each(pos, &sctp_address_families) {
            af = list_entry(pos, struct sctp_af, list);
            af->copy_addrlist(&net->sctp.local_addr_list, dev);
        }
    }
    rcu_read_unlock();
}

/* Free the existing local addresses.  */
static void sctp_free_local_addr_list(struct net *net)
{
    struct sctp_sockaddr_entry *addr;
    struct list_head *pos, *temp;

    list_for_each_safe(pos, temp, &net->sctp.local_addr_list) {
        addr = list_entry(pos, struct sctp_sockaddr_entry, list);
        list_del(pos);
        kfree(addr);
    }
}

/* Copy the local addresses which are valid for 'scope' into 'bp'.  */
int sctp_copy_local_addr_list(struct net *net, struct sctp_bind_addr *bp,
                  sctp_scope_t scope, gfp_t gfp, int copy_flags)
{
    struct sctp_sockaddr_entry *addr;
    int error = 0;

    rcu_read_lock();
    list_for_each_entry_rcu(addr, &net->sctp.local_addr_list, list) {
        if (!addr->valid)
            continue;
        if (sctp_in_scope(net, &addr->a, scope)) {
            /* Now that the address is in scope, check to see if
             * the address type is really supported by the local
             * sock as well as the remote peer.
             */
            if ((((AF_INET == addr->a.sa.sa_family) &&
                  (copy_flags & SCTP_ADDR4_PEERSUPP))) ||
                (((AF_INET6 == addr->a.sa.sa_family) &&
                  (copy_flags & SCTP_ADDR6_ALLOWED) &&
                  (copy_flags & SCTP_ADDR6_PEERSUPP)))) {
                error = sctp_add_bind_addr(bp, &addr->a,
                            SCTP_ADDR_SRC, GFP_ATOMIC);
                if (error)
                    goto end_copy;
            }
        }
    }

end_copy:
    rcu_read_unlock();
    return error;
}

/* Initialize a sctp_addr from in incoming skb.  */
static void sctp_v4_from_skb(union sctp_addr *addr, struct sk_buff *skb,
                 int is_saddr)
{
    void *from;
    __be16 *port;
    struct sctphdr *sh;

    port = &addr->v4.sin_port;
    addr->v4.sin_family = AF_INET;

    sh = sctp_hdr(skb);
    if (is_saddr) {
        *port  = sh->source;
        from = &ip_hdr(skb)->saddr;
    } else {
        *port = sh->dest;
        from = &ip_hdr(skb)->daddr;
    }
    memcpy(&addr->v4.sin_addr.s_addr, from, sizeof(struct in_addr));
}

/* Initialize an sctp_addr from a socket. */
static void sctp_v4_from_sk(union sctp_addr *addr, struct sock *sk)
{
    addr->v4.sin_family = AF_INET;
    addr->v4.sin_port = 0;
    addr->v4.sin_addr.s_addr = inet_sk(sk)->inet_rcv_saddr;
}

/* Initialize sk->sk_rcv_saddr from sctp_addr. */
static void sctp_v4_to_sk_saddr(union sctp_addr *addr, struct sock *sk)
{
    inet_sk(sk)->inet_rcv_saddr = addr->v4.sin_addr.s_addr;
}

/* Initialize sk->sk_daddr from sctp_addr. */
static void sctp_v4_to_sk_daddr(union sctp_addr *addr, struct sock *sk)
{
    inet_sk(sk)->inet_daddr = addr->v4.sin_addr.s_addr;
}

/* Initialize a sctp_addr from an address parameter. */
static void sctp_v4_from_addr_param(union sctp_addr *addr,
                    union sctp_addr_param *param,
                    __be16 port, int iif)
{
    addr->v4.sin_family = AF_INET;
    addr->v4.sin_port = port;
    addr->v4.sin_addr.s_addr = param->v4.addr.s_addr;
}

/* Initialize an address parameter from a sctp_addr and return the length
 * of the address parameter.
 */
static int sctp_v4_to_addr_param(const union sctp_addr *addr,
                 union sctp_addr_param *param)
{
    int length = sizeof(sctp_ipv4addr_param_t);

    param->v4.param_hdr.type = SCTP_PARAM_IPV4_ADDRESS;
    param->v4.param_hdr.length = htons(length);
    param->v4.addr.s_addr = addr->v4.sin_addr.s_addr;

    return length;
}

/* Initialize a sctp_addr from a dst_entry. */
static void sctp_v4_dst_saddr(union sctp_addr *saddr, struct flowi4 *fl4,
                  __be16 port)
{
    saddr->v4.sin_family = AF_INET;
    saddr->v4.sin_port = port;
    saddr->v4.sin_addr.s_addr = fl4->saddr;
}

/* Compare two addresses exactly. */
static int sctp_v4_cmp_addr(const union sctp_addr *addr1,
                const union sctp_addr *addr2)
{
    if (addr1->sa.sa_family != addr2->sa.sa_family)
        return 0;
    if (addr1->v4.sin_port != addr2->v4.sin_port)
        return 0;
    if (addr1->v4.sin_addr.s_addr != addr2->v4.sin_addr.s_addr)
        return 0;

    return 1;
}

/* Initialize addr struct to INADDR_ANY. */
static void sctp_v4_inaddr_any(union sctp_addr *addr, __be16 port)
{
    addr->v4.sin_family = AF_INET;
    addr->v4.sin_addr.s_addr = htonl(INADDR_ANY);
    addr->v4.sin_port = port;
}

/* Is this a wildcard address? */
static int sctp_v4_is_any(const union sctp_addr *addr)
{
    return htonl(INADDR_ANY) == addr->v4.sin_addr.s_addr;
}

/* This function checks if the address is a valid address to be used for
 * SCTP binding.
 *
 * Output:
 * Return 0 - If the address is a non-unicast or an illegal address.
 * Return 1 - If the address is a unicast.
 */
static int sctp_v4_addr_valid(union sctp_addr *addr,
                  struct sctp_sock *sp,
                  const struct sk_buff *skb)
{
    /* IPv4 addresses not allowed */
    if (sp && ipv6_only_sock(sctp_opt2sk(sp)))
        return 0;

    /* Is this a non-unicast address or a unusable SCTP address? */
    if (IS_IPV4_UNUSABLE_ADDRESS(addr->v4.sin_addr.s_addr))
        return 0;

    /* Is this a broadcast address? */
    if (skb && skb_rtable(skb)->rt_flags & RTCF_BROADCAST)
        return 0;

    return 1;
}

/* Should this be available for binding?   */
static int sctp_v4_available(union sctp_addr *addr, struct sctp_sock *sp)
{
    struct net *net = sock_net(&sp->inet.sk);
    int ret = inet_addr_type(net, addr->v4.sin_addr.s_addr);


    if (addr->v4.sin_addr.s_addr != htonl(INADDR_ANY) &&
       ret != RTN_LOCAL &&
       !sp->inet.freebind &&
       !sysctl_ip_nonlocal_bind)
        return 0;

    if (ipv6_only_sock(sctp_opt2sk(sp)))
        return 0;

    return 1;
}

/* Checking the loopback, private and other address scopes as defined in
 * RFC 1918.   The IPv4 scoping is based on the draft for SCTP IPv4
 * scoping <draft-stewart-tsvwg-sctp-ipv4-00.txt>.
 *
 * Level 0 - unusable SCTP addresses
 * Level 1 - loopback address
 * Level 2 - link-local addresses
 * Level 3 - private addresses.
 * Level 4 - global addresses
 * For INIT and INIT-ACK address list, let L be the level of
 * of requested destination address, sender and receiver
 * SHOULD include all of its addresses with level greater
 * than or equal to L.
 *
 * IPv4 scoping can be controlled through sysctl option
 * net.sctp.addr_scope_policy
 */
static sctp_scope_t sctp_v4_scope(union sctp_addr *addr)
{
    sctp_scope_t retval;

    /* Check for unusable SCTP addresses. */
    if (IS_IPV4_UNUSABLE_ADDRESS(addr->v4.sin_addr.s_addr)) {
        retval =  SCTP_SCOPE_UNUSABLE;
    } else if (ipv4_is_loopback(addr->v4.sin_addr.s_addr)) {
        retval = SCTP_SCOPE_LOOPBACK;
    } else if (ipv4_is_linklocal_169(addr->v4.sin_addr.s_addr)) {
        retval = SCTP_SCOPE_LINK;
    } else if (ipv4_is_private_10(addr->v4.sin_addr.s_addr) ||
           ipv4_is_private_172(addr->v4.sin_addr.s_addr) ||
           ipv4_is_private_192(addr->v4.sin_addr.s_addr)) {
        retval = SCTP_SCOPE_PRIVATE;
    } else {
        retval = SCTP_SCOPE_GLOBAL;
    }

    return retval;
}

/* Returns a valid dst cache entry for the given source and destination ip
 * addresses. If an association is passed, trys to get a dst entry with a
 * source address that matches an address in the bind address list.
 */
static void sctp_v4_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
                struct flowi *fl, struct sock *sk)
{
    struct sctp_association *asoc = t->asoc;
    struct rtable *rt;
    struct flowi4 *fl4 = &fl->u.ip4;
    struct sctp_bind_addr *bp;
    struct sctp_sockaddr_entry *laddr;
    struct dst_entry *dst = NULL;
    union sctp_addr *daddr = &t->ipaddr;
    union sctp_addr dst_saddr;

    memset(fl4, 0x0, sizeof(struct flowi4));
    fl4->daddr  = daddr->v4.sin_addr.s_addr;
    fl4->fl4_dport = daddr->v4.sin_port;
    fl4->flowi4_proto = IPPROTO_SCTP;
    if (asoc) {
        fl4->flowi4_tos = RT_CONN_FLAGS(asoc->base.sk);
        fl4->flowi4_oif = asoc->base.sk->sk_bound_dev_if;
        fl4->fl4_sport = htons(asoc->base.bind_addr.port);
    }
    if (saddr) {
        fl4->saddr = saddr->v4.sin_addr.s_addr;
        fl4->fl4_sport = saddr->v4.sin_port;
    }

    SCTP_DEBUG_PRINTK("%s: DST:%pI4, SRC:%pI4 - ",
              __func__, &fl4->daddr, &fl4->saddr);

    rt = ip_route_output_key(sock_net(sk), fl4);
    if (!IS_ERR(rt))
        dst = &rt->dst;

    /* If there is no association or if a source address is passed, no
     * more validation is required.
     */
    if (!asoc || saddr)
        goto out;

    bp = &asoc->base.bind_addr;

    if (dst) {
        /* Walk through the bind address list and look for a bind
         * address that matches the source address of the returned dst.
         */
        sctp_v4_dst_saddr(&dst_saddr, fl4, htons(bp->port));
        rcu_read_lock();
        list_for_each_entry_rcu(laddr, &bp->address_list, list) {
            if (!laddr->valid || (laddr->state == SCTP_ADDR_DEL) ||
                (laddr->state != SCTP_ADDR_SRC &&
                !asoc->src_out_of_asoc_ok))
                continue;
            if (sctp_v4_cmp_addr(&dst_saddr, &laddr->a))
                goto out_unlock;
        }
        rcu_read_unlock();

        /* None of the bound addresses match the source address of the
         * dst. So release it.
         */
        dst_release(dst);
        dst = NULL;
    }

    /* Walk through the bind address list and try to get a dst that
     * matches a bind address as the source address.
     */
    rcu_read_lock();
    list_for_each_entry_rcu(laddr, &bp->address_list, list) {
        if (!laddr->valid)
            continue;
        if ((laddr->state == SCTP_ADDR_SRC) &&
            (AF_INET == laddr->a.sa.sa_family)) {
            fl4->saddr = laddr->a.v4.sin_addr.s_addr;
            fl4->fl4_sport = laddr->a.v4.sin_port;
            rt = ip_route_output_key(sock_net(sk), fl4);
            if (!IS_ERR(rt)) {
                dst = &rt->dst;
                goto out_unlock;
            }
        }
    }

out_unlock:
    rcu_read_unlock();
out:
    t->dst = dst;
    if (dst)
        SCTP_DEBUG_PRINTK("rt_dst:%pI4, rt_src:%pI4\n",
                  &fl4->daddr, &fl4->saddr);
    else
        SCTP_DEBUG_PRINTK("NO ROUTE\n");
}

/* For v4, the source address is cached in the route entry(dst). So no need
 * to cache it separately and hence this is an empty routine.
 */
static void sctp_v4_get_saddr(struct sctp_sock *sk,
                  struct sctp_transport *t,
                  struct flowi *fl)
{
    union sctp_addr *saddr = &t->saddr;
    struct rtable *rt = (struct rtable *)t->dst;

    if (rt) {
        saddr->v4.sin_family = AF_INET;
        saddr->v4.sin_addr.s_addr = fl->u.ip4.saddr;
    }
}

/* What interface did this skb arrive on? */
static int sctp_v4_skb_iif(const struct sk_buff *skb)
{
    return inet_iif(skb);
}

/* Was this packet marked by Explicit Congestion Notification? */
static int sctp_v4_is_ce(const struct sk_buff *skb)
{
    return INET_ECN_is_ce(ip_hdr(skb)->tos);
}

/* Create and initialize a new sk for the socket returned by accept(). */
static struct sock *sctp_v4_create_accept_sk(struct sock *sk,
                         struct sctp_association *asoc)
{
    struct sock *newsk = sk_alloc(sock_net(sk), PF_INET, GFP_KERNEL,
            sk->sk_prot);
    struct inet_sock *newinet;

    if (!newsk)
        goto out;

    sock_init_data(NULL, newsk);

    sctp_copy_sock(newsk, sk, asoc);
    sock_reset_flag(newsk, SOCK_ZAPPED);

    newinet = inet_sk(newsk);

    newinet->inet_daddr = asoc->peer.primary_addr.v4.sin_addr.s_addr;

    sk_refcnt_debug_inc(newsk);

    if (newsk->sk_prot->init(newsk)) {
        sk_common_release(newsk);
        newsk = NULL;
    }

out:
    return newsk;
}

/* Map address, empty for v4 family */
static void sctp_v4_addr_v4map(struct sctp_sock *sp, union sctp_addr *addr)
{
    /* Empty */
}

/* Dump the v4 addr to the seq file. */
static void sctp_v4_seq_dump_addr(struct seq_file *seq, union sctp_addr *addr)
{
    seq_printf(seq, "%pI4 ", &addr->v4.sin_addr);
}

static void sctp_v4_ecn_capable(struct sock *sk)
{
    INET_ECN_xmit(sk);
}

void sctp_addr_wq_timeout_handler(unsigned long arg)
{
    struct net *net = (struct net *)arg;
    struct sctp_sockaddr_entry *addrw, *temp;
    struct sctp_sock *sp;

    spin_lock_bh(&net->sctp.addr_wq_lock);

    list_for_each_entry_safe(addrw, temp, &net->sctp.addr_waitq, list) {
        SCTP_DEBUG_PRINTK_IPADDR("sctp_addrwq_timo_handler: the first ent in wq %p is ",
            " for cmd %d at entry %p\n", &net->sctp.addr_waitq, &addrw->a, addrw->state,
            addrw);

#if IS_ENABLED(CONFIG_IPV6)
        /* Now we send an ASCONF for each association */
        /* Note. we currently don't handle link local IPv6 addressees */
        if (addrw->a.sa.sa_family == AF_INET6) {
            struct in6_addr *in6;

            if (ipv6_addr_type(&addrw->a.v6.sin6_addr) &
                IPV6_ADDR_LINKLOCAL)
                goto free_next;

            in6 = (struct in6_addr *)&addrw->a.v6.sin6_addr;
            if (ipv6_chk_addr(net, in6, NULL, 0) == 0 &&
                addrw->state == SCTP_ADDR_NEW) {
                unsigned long timeo_val;

                SCTP_DEBUG_PRINTK("sctp_timo_handler: this is on DAD, trying %d sec later\n",
                    SCTP_ADDRESS_TICK_DELAY);
                timeo_val = jiffies;
                timeo_val += msecs_to_jiffies(SCTP_ADDRESS_TICK_DELAY);
                mod_timer(&net->sctp.addr_wq_timer, timeo_val);
                break;
            }
        }
#endif
        list_for_each_entry(sp, &net->sctp.auto_asconf_splist, auto_asconf_list) {
            struct sock *sk;

            sk = sctp_opt2sk(sp);
            /* ignore bound-specific endpoints */
            if (!sctp_is_ep_boundall(sk))
                continue;
            sctp_bh_lock_sock(sk);
            if (sctp_asconf_mgmt(sp, addrw) < 0)
                SCTP_DEBUG_PRINTK("sctp_addrwq_timo_handler: sctp_asconf_mgmt failed\n");
            sctp_bh_unlock_sock(sk);
        }
#if IS_ENABLED(CONFIG_IPV6)
free_next:
#endif
        list_del(&addrw->list);
        kfree(addrw);
    }
    spin_unlock_bh(&net->sctp.addr_wq_lock);
}

static void sctp_free_addr_wq(struct net *net)
{
    struct sctp_sockaddr_entry *addrw;
    struct sctp_sockaddr_entry *temp;

    spin_lock_bh(&net->sctp.addr_wq_lock);
    del_timer(&net->sctp.addr_wq_timer);
    list_for_each_entry_safe(addrw, temp, &net->sctp.addr_waitq, list) {
        list_del(&addrw->list);
        kfree(addrw);
    }
    spin_unlock_bh(&net->sctp.addr_wq_lock);
}

/* lookup the entry for the same address in the addr_waitq
 * sctp_addr_wq MUST be locked
 */
static struct sctp_sockaddr_entry *sctp_addr_wq_lookup(struct net *net,
                    struct sctp_sockaddr_entry *addr)
{
    struct sctp_sockaddr_entry *addrw;

    list_for_each_entry(addrw, &net->sctp.addr_waitq, list) {
        if (addrw->a.sa.sa_family != addr->a.sa.sa_family)
            continue;
        if (addrw->a.sa.sa_family == AF_INET) {
            if (addrw->a.v4.sin_addr.s_addr ==
                addr->a.v4.sin_addr.s_addr)
                return addrw;
        } else if (addrw->a.sa.sa_family == AF_INET6) {
            if (ipv6_addr_equal(&addrw->a.v6.sin6_addr,
                &addr->a.v6.sin6_addr))
                return addrw;
        }
    }
    return NULL;
}

void sctp_addr_wq_mgmt(struct net *net, struct sctp_sockaddr_entry *addr, int cmd)
{
    struct sctp_sockaddr_entry *addrw;
    unsigned long timeo_val;

    /* first, we check if an opposite message already exist in the queue.
     * If we found such message, it is removed.
     * This operation is a bit stupid, but the DHCP client attaches the
     * new address after a couple of addition and deletion of that address
     */

    spin_lock_bh(&net->sctp.addr_wq_lock);
    /* Offsets existing events in addr_wq */
    addrw = sctp_addr_wq_lookup(net, addr);
    if (addrw) {
        if (addrw->state != cmd) {
            SCTP_DEBUG_PRINTK_IPADDR("sctp_addr_wq_mgmt offsets existing entry for %d ",
                " in wq %p\n", addrw->state, &addrw->a,
                &net->sctp.addr_waitq);
            list_del(&addrw->list);
            kfree(addrw);
        }
        spin_unlock_bh(&net->sctp.addr_wq_lock);
        return;
    }

    /* OK, we have to add the new address to the wait queue */
    addrw = kmemdup(addr, sizeof(struct sctp_sockaddr_entry), GFP_ATOMIC);
    if (addrw == NULL) {
        spin_unlock_bh(&net->sctp.addr_wq_lock);
        return;
    }
    addrw->state = cmd;
    list_add_tail(&addrw->list, &net->sctp.addr_waitq);
    SCTP_DEBUG_PRINTK_IPADDR("sctp_addr_wq_mgmt add new entry for cmd:%d ",
        " in wq %p\n", addrw->state, &addrw->a, &net->sctp.addr_waitq);

    if (!timer_pending(&net->sctp.addr_wq_timer)) {
        timeo_val = jiffies;
        timeo_val += msecs_to_jiffies(SCTP_ADDRESS_TICK_DELAY);
        mod_timer(&net->sctp.addr_wq_timer, timeo_val);
    }
    spin_unlock_bh(&net->sctp.addr_wq_lock);
}

/* Event handler for inet address addition/deletion events.
 * The sctp_local_addr_list needs to be protocted by a spin lock since
 * multiple notifiers (say IPv4 and IPv6) may be running at the same
 * time and thus corrupt the list.
 * The reader side is protected with RCU.
 */
static int sctp_inetaddr_event(struct notifier_block *this, unsigned long ev,
                   void *ptr)
{
    struct in_ifaddr *ifa = (struct in_ifaddr *)ptr;
    struct sctp_sockaddr_entry *addr = NULL;
    struct sctp_sockaddr_entry *temp;
    struct net *net = dev_net(ifa->ifa_dev->dev);
    int found = 0;

    switch (ev) {
    case NETDEV_UP:
        addr = kmalloc(sizeof(struct sctp_sockaddr_entry), GFP_ATOMIC);
        if (addr) {
            addr->a.v4.sin_family = AF_INET;
            addr->a.v4.sin_port = 0;
            addr->a.v4.sin_addr.s_addr = ifa->ifa_local;
            addr->valid = 1;
            spin_lock_bh(&net->sctp.local_addr_lock);
            list_add_tail_rcu(&addr->list, &net->sctp.local_addr_list);
            sctp_addr_wq_mgmt(net, addr, SCTP_ADDR_NEW);
            spin_unlock_bh(&net->sctp.local_addr_lock);
        }
        break;
    case NETDEV_DOWN:
        spin_lock_bh(&net->sctp.local_addr_lock);
        list_for_each_entry_safe(addr, temp,
                    &net->sctp.local_addr_list, list) {
            if (addr->a.sa.sa_family == AF_INET &&
                    addr->a.v4.sin_addr.s_addr ==
                    ifa->ifa_local) {
                sctp_addr_wq_mgmt(net, addr, SCTP_ADDR_DEL);
                found = 1;
                addr->valid = 0;
                list_del_rcu(&addr->list);
                break;
            }
        }
        spin_unlock_bh(&net->sctp.local_addr_lock);
        if (found)
            kfree_rcu(addr, rcu);
        break;
    }

    return NOTIFY_DONE;
}

/*
 * Initialize the control inode/socket with a control endpoint data
 * structure.  This endpoint is reserved exclusively for the OOTB processing.
 */
static int sctp_ctl_sock_init(struct net *net)
{
    int err;
    sa_family_t family = PF_INET;

    if (sctp_get_pf_specific(PF_INET6))
        family = PF_INET6;

    err = inet_ctl_sock_create(&net->sctp.ctl_sock, family,
                   SOCK_SEQPACKET, IPPROTO_SCTP, net);

    /* If IPv6 socket could not be created, try the IPv4 socket */
    if (err < 0 && family == PF_INET6)
        err = inet_ctl_sock_create(&net->sctp.ctl_sock, AF_INET,
                       SOCK_SEQPACKET, IPPROTO_SCTP,
                       net);

    if (err < 0) {
        pr_err("Failed to create the SCTP control socket\n");
        return err;
    }
    return 0;
}

/* Register address family specific functions. */
int sctp_register_af(struct sctp_af *af)
{
    switch (af->sa_family) {
    case AF_INET:
        if (sctp_af_v4_specific)
            return 0;
        sctp_af_v4_specific = af;
        break;
    case AF_INET6:
        if (sctp_af_v6_specific)
            return 0;
        sctp_af_v6_specific = af;
        break;
    default:
        return 0;
    }

    INIT_LIST_HEAD(&af->list);
    list_add_tail(&af->list, &sctp_address_families);
    return 1;
}

/* Get the table of functions for manipulating a particular address
 * family.
 */
struct sctp_af *sctp_get_af_specific(sa_family_t family)
{
    switch (family) {
    case AF_INET:
        return sctp_af_v4_specific;
    case AF_INET6:
        return sctp_af_v6_specific;
    default:
        return NULL;
    }
}

/* Common code to initialize a AF_INET msg_name. */
static void sctp_inet_msgname(char *msgname, int *addr_len)
{
    struct sockaddr_in *sin;

    sin = (struct sockaddr_in *)msgname;
    *addr_len = sizeof(struct sockaddr_in);
    sin->sin_family = AF_INET;
    memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
}

/* Copy the primary address of the peer primary address as the msg_name. */
static void sctp_inet_event_msgname(struct sctp_ulpevent *event, char *msgname,
                    int *addr_len)
{
    struct sockaddr_in *sin, *sinfrom;

    if (msgname) {
        struct sctp_association *asoc;

        asoc = event->asoc;
        sctp_inet_msgname(msgname, addr_len);
        sin = (struct sockaddr_in *)msgname;
        sinfrom = &asoc->peer.primary_addr.v4;
        sin->sin_port = htons(asoc->peer.port);
        sin->sin_addr.s_addr = sinfrom->sin_addr.s_addr;
    }
}

/* Initialize and copy out a msgname from an inbound skb. */
static void sctp_inet_skb_msgname(struct sk_buff *skb, char *msgname, int *len)
{
    if (msgname) {
        struct sctphdr *sh = sctp_hdr(skb);
        struct sockaddr_in *sin = (struct sockaddr_in *)msgname;

        sctp_inet_msgname(msgname, len);
        sin->sin_port = sh->source;
        sin->sin_addr.s_addr = ip_hdr(skb)->saddr;
    }
}

/* Do we support this AF? */
static int sctp_inet_af_supported(sa_family_t family, struct sctp_sock *sp)
{
    /* PF_INET only supports AF_INET addresses. */
    return AF_INET == family;
}

/* Address matching with wildcards allowed. */
static int sctp_inet_cmp_addr(const union sctp_addr *addr1,
                  const union sctp_addr *addr2,
                  struct sctp_sock *opt)
{
    /* PF_INET only supports AF_INET addresses. */
    if (addr1->sa.sa_family != addr2->sa.sa_family)
        return 0;
    if (htonl(INADDR_ANY) == addr1->v4.sin_addr.s_addr ||
        htonl(INADDR_ANY) == addr2->v4.sin_addr.s_addr)
        return 1;
    if (addr1->v4.sin_addr.s_addr == addr2->v4.sin_addr.s_addr)
        return 1;

    return 0;
}

/* Verify that provided sockaddr looks bindable.  Common verification has
 * already been taken care of.
 */
static int sctp_inet_bind_verify(struct sctp_sock *opt, union sctp_addr *addr)
{
    return sctp_v4_available(addr, opt);
}

/* Verify that sockaddr looks sendable.  Common verification has already
 * been taken care of.
 */
static int sctp_inet_send_verify(struct sctp_sock *opt, union sctp_addr *addr)
{
    return 1;
}

/* Fill in Supported Address Type information for INIT and INIT-ACK
 * chunks.  Returns number of addresses supported.
 */
static int sctp_inet_supported_addrs(const struct sctp_sock *opt,
                     __be16 *types)
{
    types[0] = SCTP_PARAM_IPV4_ADDRESS;
    return 1;
}

/* Wrapper routine that calls the ip transmit routine. */
static inline int sctp_v4_xmit(struct sk_buff *skb,
                   struct sctp_transport *transport)
{
    struct inet_sock *inet = inet_sk(skb->sk);

    SCTP_DEBUG_PRINTK("%s: skb:%p, len:%d, src:%pI4, dst:%pI4\n",
              __func__, skb, skb->len,
              &transport->fl.u.ip4.saddr,
              &transport->fl.u.ip4.daddr);

    inet->pmtudisc = transport->param_flags & SPP_PMTUD_ENABLE ?
             IP_PMTUDISC_DO : IP_PMTUDISC_DONT;

    SCTP_INC_STATS(sock_net(&inet->sk), SCTP_MIB_OUTSCTPPACKS);
    return ip_queue_xmit(skb, &transport->fl);
}

static struct sctp_af sctp_af_inet;

static struct sctp_pf sctp_pf_inet = {
    .event_msgname = sctp_inet_event_msgname,
    .skb_msgname   = sctp_inet_skb_msgname,
    .af_supported  = sctp_inet_af_supported,
    .cmp_addr      = sctp_inet_cmp_addr,
    .bind_verify   = sctp_inet_bind_verify,
    .send_verify   = sctp_inet_send_verify,
    .supported_addrs = sctp_inet_supported_addrs,
    .create_accept_sk = sctp_v4_create_accept_sk,
    .addr_v4map = sctp_v4_addr_v4map,
    .af            = &sctp_af_inet
};

/* Notifier for inetaddr addition/deletion events.  */
static struct notifier_block sctp_inetaddr_notifier = {
    .notifier_call = sctp_inetaddr_event,
};

/* Socket operations.  */
static const struct proto_ops inet_seqpacket_ops = {
    .family        = PF_INET,
    .owner         = THIS_MODULE,
    .release       = inet_release,  /* Needs to be wrapped... */
    .bind          = inet_bind,
    .connect       = inet_dgram_connect,
    .socketpair    = sock_no_socketpair,
    .accept        = inet_accept,
    .getname       = inet_getname,  /* Semantics are different.  */
    .poll          = sctp_poll,
    .ioctl         = inet_ioctl,
    .listen        = sctp_inet_listen,
    .shutdown      = inet_shutdown, /* Looks harmless.  */
    .setsockopt    = sock_common_setsockopt, /* IP_SOL IP_OPTION is a problem */
    .getsockopt    = sock_common_getsockopt,
    .sendmsg       = inet_sendmsg,
    .recvmsg       = sock_common_recvmsg,
    .mmap          = sock_no_mmap,
    .sendpage      = sock_no_sendpage,
#ifdef CONFIG_COMPAT
    .compat_setsockopt = compat_sock_common_setsockopt,
    .compat_getsockopt = compat_sock_common_getsockopt,
#endif
};

/* Registration with AF_INET family.  */
static struct inet_protosw sctp_seqpacket_protosw = {
    .type       = SOCK_SEQPACKET,
    .protocol   = IPPROTO_SCTP,
    .prot       = &sctp_prot,
    .ops        = &inet_seqpacket_ops,
    .no_check   = 0,
    .flags      = SCTP_PROTOSW_FLAG
};
static struct inet_protosw sctp_stream_protosw = {
    .type       = SOCK_STREAM,
    .protocol   = IPPROTO_SCTP,
    .prot       = &sctp_prot,
    .ops        = &inet_seqpacket_ops,
    .no_check   = 0,
    .flags      = SCTP_PROTOSW_FLAG
};

/* Register with IP layer.  */
static const struct net_protocol sctp_protocol = {
    .handler     = sctp_rcv,
    .err_handler = sctp_v4_err,
    .no_policy   = 1,
    .netns_ok    = 1,
};

/* IPv4 address related functions.  */
static struct sctp_af sctp_af_inet = {
    .sa_family     = AF_INET,
    .sctp_xmit     = sctp_v4_xmit,
    .setsockopt    = ip_setsockopt,
    .getsockopt    = ip_getsockopt,
    .get_dst       = sctp_v4_get_dst,
    .get_saddr     = sctp_v4_get_saddr,
    .copy_addrlist     = sctp_v4_copy_addrlist,
    .from_skb      = sctp_v4_from_skb,
    .from_sk       = sctp_v4_from_sk,
    .to_sk_saddr       = sctp_v4_to_sk_saddr,
    .to_sk_daddr       = sctp_v4_to_sk_daddr,
    .from_addr_param   = sctp_v4_from_addr_param,
    .to_addr_param     = sctp_v4_to_addr_param,
    .cmp_addr      = sctp_v4_cmp_addr,
    .addr_valid    = sctp_v4_addr_valid,
    .inaddr_any    = sctp_v4_inaddr_any,
    .is_any        = sctp_v4_is_any,
    .available     = sctp_v4_available,
    .scope         = sctp_v4_scope,
    .skb_iif       = sctp_v4_skb_iif,
    .is_ce         = sctp_v4_is_ce,
    .seq_dump_addr     = sctp_v4_seq_dump_addr,
    .ecn_capable       = sctp_v4_ecn_capable,
    .net_header_len    = sizeof(struct iphdr),
    .sockaddr_len      = sizeof(struct sockaddr_in),
#ifdef CONFIG_COMPAT
    .compat_setsockopt = compat_ip_setsockopt,
    .compat_getsockopt = compat_ip_getsockopt,
#endif
};

struct sctp_pf *sctp_get_pf_specific(sa_family_t family) {

    switch (family) {
    case PF_INET:
        return sctp_pf_inet_specific;
    case PF_INET6:
        return sctp_pf_inet6_specific;
    default:
        return NULL;
    }
}

/* Register the PF specific function table.  */
int sctp_register_pf(struct sctp_pf *pf, sa_family_t family)
{
    switch (family) {
    case PF_INET:
        if (sctp_pf_inet_specific)
            return 0;
        sctp_pf_inet_specific = pf;
        break;
    case PF_INET6:
        if (sctp_pf_inet6_specific)
            return 0;
        sctp_pf_inet6_specific = pf;
        break;
    default:
        return 0;
    }
    return 1;
}

static inline int init_sctp_mibs(struct net *net)
{
    return snmp_mib_init((void __percpu **)net->sctp.sctp_statistics,
                 sizeof(struct sctp_mib),
                 __alignof__(struct sctp_mib));
}

static inline void cleanup_sctp_mibs(struct net *net)
{
    snmp_mib_free((void __percpu **)net->sctp.sctp_statistics);
}

static void sctp_v4_pf_init(void)
{
    /* Initialize the SCTP specific PF functions. */
    sctp_register_pf(&sctp_pf_inet, PF_INET);
    sctp_register_af(&sctp_af_inet);
}

static void sctp_v4_pf_exit(void)
{
    list_del(&sctp_af_inet.list);
}

static int sctp_v4_protosw_init(void)
{
    int rc;

    rc = proto_register(&sctp_prot, 1);
    if (rc)
        return rc;

    /* Register SCTP(UDP and TCP style) with socket layer.  */
    inet_register_protosw(&sctp_seqpacket_protosw);
    inet_register_protosw(&sctp_stream_protosw);

    return 0;
}

static void sctp_v4_protosw_exit(void)
{
    inet_unregister_protosw(&sctp_stream_protosw);
    inet_unregister_protosw(&sctp_seqpacket_protosw);
    proto_unregister(&sctp_prot);
}

static int sctp_v4_add_protocol(void)
{
    /* Register notifier for inet address additions/deletions. */
    register_inetaddr_notifier(&sctp_inetaddr_notifier);

    /* Register SCTP with inet layer.  */
    if (inet_add_protocol(&sctp_protocol, IPPROTO_SCTP) < 0)
        return -EAGAIN;

    return 0;
}

static void sctp_v4_del_protocol(void)
{
    inet_del_protocol(&sctp_protocol, IPPROTO_SCTP);
    unregister_inetaddr_notifier(&sctp_inetaddr_notifier);
}

static int sctp_net_init(struct net *net)
{
    int status;

    /*
     * 14. Suggested SCTP Protocol Parameter Values
     */
    /* The following protocol parameters are RECOMMENDED:  */
    /* RTO.Initial              - 3  seconds */
    net->sctp.rto_initial           = SCTP_RTO_INITIAL;
    /* RTO.Min                  - 1  second */
    net->sctp.rto_min           = SCTP_RTO_MIN;
    /* RTO.Max                 -  60 seconds */
    net->sctp.rto_max           = SCTP_RTO_MAX;
    /* RTO.Alpha                - 1/8 */
    net->sctp.rto_alpha         = SCTP_RTO_ALPHA;
    /* RTO.Beta                 - 1/4 */
    net->sctp.rto_beta          = SCTP_RTO_BETA;

    /* Valid.Cookie.Life        - 60  seconds */
    net->sctp.valid_cookie_life     = SCTP_DEFAULT_COOKIE_LIFE;

    /* Whether Cookie Preservative is enabled(1) or not(0) */
    net->sctp.cookie_preserve_enable    = 1;

    /* Max.Burst            - 4 */
    net->sctp.max_burst         = SCTP_DEFAULT_MAX_BURST;

    /* Association.Max.Retrans  - 10 attempts
     * Path.Max.Retrans         - 5  attempts (per destination address)
     * Max.Init.Retransmits     - 8  attempts
     */
    net->sctp.max_retrans_association   = 10;
    net->sctp.max_retrans_path      = 5;
    net->sctp.max_retrans_init      = 8;

    /* Sendbuffer growth        - do per-socket accounting */
    net->sctp.sndbuf_policy         = 0;

    /* Rcvbuffer growth     - do per-socket accounting */
    net->sctp.rcvbuf_policy         = 0;

    /* HB.interval              - 30 seconds */
    net->sctp.hb_interval           = SCTP_DEFAULT_TIMEOUT_HEARTBEAT;

    /* delayed SACK timeout */
    net->sctp.sack_timeout          = SCTP_DEFAULT_TIMEOUT_SACK;

    /* Disable ADDIP by default. */
    net->sctp.addip_enable = 0;
    net->sctp.addip_noauth = 0;
    net->sctp.default_auto_asconf = 0;

    /* Enable PR-SCTP by default. */
    net->sctp.prsctp_enable = 1;

    /* Disable AUTH by default. */
    net->sctp.auth_enable = 0;

    /* Set SCOPE policy to enabled */
    net->sctp.scope_policy = SCTP_SCOPE_POLICY_ENABLE;

    /* Set the default rwnd update threshold */
    net->sctp.rwnd_upd_shift = SCTP_DEFAULT_RWND_SHIFT;

    /* Initialize maximum autoclose timeout. */
    net->sctp.max_autoclose     = INT_MAX / HZ;

    status = sctp_sysctl_net_register(net);
    if (status)
        goto err_sysctl_register;

    /* Allocate and initialise sctp mibs.  */
    status = init_sctp_mibs(net);
    if (status)
        goto err_init_mibs;

    /* Initialize proc fs directory.  */
    status = sctp_proc_init(net);
    if (status)
        goto err_init_proc;

    sctp_dbg_objcnt_init(net);

    /* Initialize the control inode/socket for handling OOTB packets.  */
    if ((status = sctp_ctl_sock_init(net))) {
        pr_err("Failed to initialize the SCTP control sock\n");
        goto err_ctl_sock_init;
    }

    /* Initialize the local address list. */
    INIT_LIST_HEAD(&net->sctp.local_addr_list);
    spin_lock_init(&net->sctp.local_addr_lock);
    sctp_get_local_addr_list(net);

    /* Initialize the address event list */
    INIT_LIST_HEAD(&net->sctp.addr_waitq);
    INIT_LIST_HEAD(&net->sctp.auto_asconf_splist);
    spin_lock_init(&net->sctp.addr_wq_lock);
    net->sctp.addr_wq_timer.expires = 0;
    setup_timer(&net->sctp.addr_wq_timer, sctp_addr_wq_timeout_handler,
            (unsigned long)net);

    return 0;

err_ctl_sock_init:
    sctp_dbg_objcnt_exit(net);
    sctp_proc_exit(net);
err_init_proc:
    cleanup_sctp_mibs(net);
err_init_mibs:
    sctp_sysctl_net_unregister(net);
err_sysctl_register:
    return status;
}

static void sctp_net_exit(struct net *net)
{
    /* Free the local address list */
    sctp_free_addr_wq(net);
    sctp_free_local_addr_list(net);

    /* Free the control endpoint.  */
    inet_ctl_sock_destroy(net->sctp.ctl_sock);

    sctp_dbg_objcnt_exit(net);

    sctp_proc_exit(net);
    cleanup_sctp_mibs(net);
    sctp_sysctl_net_unregister(net);
}

static struct pernet_operations sctp_net_ops = {
    .init = sctp_net_init,
    .exit = sctp_net_exit,
};

/* Initialize the universe into something sensible.  */
SCTP_STATIC __init int sctp_init(void)
{
    int i;
    int status = -EINVAL;
    unsigned long goal;
    unsigned long limit;
    int max_share;
    int order;

    /* SCTP_DEBUG sanity check. */
    if (!sctp_sanity_check())
        goto out;

    /* Allocate bind_bucket and chunk caches. */
    status = -ENOBUFS;
    sctp_bucket_cachep = kmem_cache_create("sctp_bind_bucket",
                           sizeof(struct sctp_bind_bucket),
                           0, SLAB_HWCACHE_ALIGN,
                           NULL);
    if (!sctp_bucket_cachep)
        goto out;

    sctp_chunk_cachep = kmem_cache_create("sctp_chunk",
                           sizeof(struct sctp_chunk),
                           0, SLAB_HWCACHE_ALIGN,
                           NULL);
    if (!sctp_chunk_cachep)
        goto err_chunk_cachep;

    status = percpu_counter_init(&sctp_sockets_allocated, 0);
    if (status)
        goto err_percpu_counter_init;

    /* Implementation specific variables. */

    /* Initialize default stream count setup information. */
    sctp_max_instreams          = SCTP_DEFAULT_INSTREAMS;
    sctp_max_outstreams         = SCTP_DEFAULT_OUTSTREAMS;

    /* Initialize handle used for association ids. */
    idr_init(&sctp_assocs_id);

    limit = nr_free_buffer_pages() / 8;
    limit = max(limit, 128UL);
    sysctl_sctp_mem[0] = limit / 4 * 3;
    sysctl_sctp_mem[1] = limit;
    sysctl_sctp_mem[2] = sysctl_sctp_mem[0] * 2;

    /* Set per-socket limits to no more than 1/128 the pressure threshold*/
    limit = (sysctl_sctp_mem[1]) << (PAGE_SHIFT - 7);
    max_share = min(4UL*1024*1024, limit);

    sysctl_sctp_rmem[0] = SK_MEM_QUANTUM; /* give each asoc 1 page min */
    sysctl_sctp_rmem[1] = 1500 * SKB_TRUESIZE(1);
    sysctl_sctp_rmem[2] = max(sysctl_sctp_rmem[1], max_share);

    sysctl_sctp_wmem[0] = SK_MEM_QUANTUM;
    sysctl_sctp_wmem[1] = 16*1024;
    sysctl_sctp_wmem[2] = max(64*1024, max_share);

    /* Size and allocate the association hash table.
     * The methodology is similar to that of the tcp hash tables.
     */
    if (totalram_pages >= (128 * 1024))
        goal = totalram_pages >> (22 - PAGE_SHIFT);
    else
        goal = totalram_pages >> (24 - PAGE_SHIFT);

    for (order = 0; (1UL << order) < goal; order++)
        ;

    do {
        sctp_assoc_hashsize = (1UL << order) * PAGE_SIZE /
                    sizeof(struct sctp_hashbucket);
        if ((sctp_assoc_hashsize > (64 * 1024)) && order > 0)
            continue;
        sctp_assoc_hashtable = (struct sctp_hashbucket *)
            __get_free_pages(GFP_ATOMIC|__GFP_NOWARN, order);
    } while (!sctp_assoc_hashtable && --order > 0);
    if (!sctp_assoc_hashtable) {
        pr_err("Failed association hash alloc\n");
        status = -ENOMEM;
        goto err_ahash_alloc;
    }
    for (i = 0; i < sctp_assoc_hashsize; i++) {
        rwlock_init(&sctp_assoc_hashtable[i].lock);
        INIT_HLIST_HEAD(&sctp_assoc_hashtable[i].chain);
    }

    /* Allocate and initialize the endpoint hash table.  */
    sctp_ep_hashsize = 64;
    sctp_ep_hashtable = (struct sctp_hashbucket *)
        kmalloc(64 * sizeof(struct sctp_hashbucket), GFP_KERNEL);
    if (!sctp_ep_hashtable) {
        pr_err("Failed endpoint_hash alloc\n");
        status = -ENOMEM;
        goto err_ehash_alloc;
    }
    for (i = 0; i < sctp_ep_hashsize; i++) {
        rwlock_init(&sctp_ep_hashtable[i].lock);
        INIT_HLIST_HEAD(&sctp_ep_hashtable[i].chain);
    }

    /* Allocate and initialize the SCTP port hash table.  */
    do {
        sctp_port_hashsize = (1UL << order) * PAGE_SIZE /
                    sizeof(struct sctp_bind_hashbucket);
        if ((sctp_port_hashsize > (64 * 1024)) && order > 0)
            continue;
        sctp_port_hashtable = (struct sctp_bind_hashbucket *)
            __get_free_pages(GFP_ATOMIC|__GFP_NOWARN, order);
    } while (!sctp_port_hashtable && --order > 0);
    if (!sctp_port_hashtable) {
        pr_err("Failed bind hash alloc\n");
        status = -ENOMEM;
        goto err_bhash_alloc;
    }
    for (i = 0; i < sctp_port_hashsize; i++) {
        spin_lock_init(&sctp_port_hashtable[i].lock);
        INIT_HLIST_HEAD(&sctp_port_hashtable[i].chain);
    }

    pr_info("Hash tables configured (established %d bind %d)\n",
        sctp_assoc_hashsize, sctp_port_hashsize);

    sctp_sysctl_register();

    INIT_LIST_HEAD(&sctp_address_families);
    sctp_v4_pf_init();
    sctp_v6_pf_init();

    status = sctp_v4_protosw_init();

    if (status)
        goto err_protosw_init;

    status = sctp_v6_protosw_init();
    if (status)
        goto err_v6_protosw_init;

    status = register_pernet_subsys(&sctp_net_ops);
    if (status)
        goto err_register_pernet_subsys;

    status = sctp_v4_add_protocol();
    if (status)
        goto err_add_protocol;

    /* Register SCTP with inet6 layer.  */
    status = sctp_v6_add_protocol();
    if (status)
        goto err_v6_add_protocol;

    status = 0;
out:
    return status;
err_v6_add_protocol:
    sctp_v4_del_protocol();
err_add_protocol:
    unregister_pernet_subsys(&sctp_net_ops);
err_register_pernet_subsys:
    sctp_v6_protosw_exit();
err_v6_protosw_init:
    sctp_v4_protosw_exit();
err_protosw_init:
    sctp_v4_pf_exit();
    sctp_v6_pf_exit();
    sctp_sysctl_unregister();
    free_pages((unsigned long)sctp_port_hashtable,
           get_order(sctp_port_hashsize *
                 sizeof(struct sctp_bind_hashbucket)));
err_bhash_alloc:
    kfree(sctp_ep_hashtable);
err_ehash_alloc:
    free_pages((unsigned long)sctp_assoc_hashtable,
           get_order(sctp_assoc_hashsize *
                 sizeof(struct sctp_hashbucket)));
err_ahash_alloc:
    percpu_counter_destroy(&sctp_sockets_allocated);
err_percpu_counter_init:
    kmem_cache_destroy(sctp_chunk_cachep);
err_chunk_cachep:
    kmem_cache_destroy(sctp_bucket_cachep);
    goto out;
}

/* Exit handler for the SCTP protocol.  */
SCTP_STATIC __exit void sctp_exit(void)
{
    /* BUG.  This should probably do something useful like clean
     * up all the remaining associations and all that memory.
     */

    /* Unregister with inet6/inet layers. */
    sctp_v6_del_protocol();
    sctp_v4_del_protocol();

    unregister_pernet_subsys(&sctp_net_ops);

    /* Free protosw registrations */
    sctp_v6_protosw_exit();
    sctp_v4_protosw_exit();

    /* Unregister with socket layer. */
    sctp_v6_pf_exit();
    sctp_v4_pf_exit();

    sctp_sysctl_unregister();

    free_pages((unsigned long)sctp_assoc_hashtable,
           get_order(sctp_assoc_hashsize *
                 sizeof(struct sctp_hashbucket)));
    kfree(sctp_ep_hashtable);
    free_pages((unsigned long)sctp_port_hashtable,
           get_order(sctp_port_hashsize *
                 sizeof(struct sctp_bind_hashbucket)));

    percpu_counter_destroy(&sctp_sockets_allocated);

    rcu_barrier(); /* Wait for completion of call_rcu()'s */

    kmem_cache_destroy(sctp_chunk_cachep);
    kmem_cache_destroy(sctp_bucket_cachep);
}

module_init(sctp_init);
module_exit(sctp_exit);

/*
 * __stringify doesn't likes enums, so use IPPROTO_SCTP value (132) directly.
 */
MODULE_ALIAS("net-pf-" __stringify(PF_INET) "-proto-132");
MODULE_ALIAS("net-pf-" __stringify(PF_INET6) "-proto-132");
MODULE_AUTHOR("Linux Kernel SCTP developers <[email protected]>");
MODULE_DESCRIPTION("Support for the SCTP protocol (RFC2960)");
module_param_named(no_checksums, sctp_checksum_disable, bool, 0644);
MODULE_PARM_DESC(no_checksums, "Disable checksums computing and verification");
MODULE_LICENSE("GPL");