SCTP: change sctp_ctl_sock_init() to try IPv4 if IPv6 fails

[linux/fpc-iii.git] / net / sctp / protocol.c

/* 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 <lksctp-developers@lists.sourceforge.net>
 *
 * Or submit a bug report through the following website:
 *    http://www.sf.net/projects/lksctp
 *
 * Written or modified by:
 *    La Monte H.P. Yarroll <piggy@acm.org>
 *    Karl Knutson <karl@athena.chicago.il.us>
 *    Jon Grimm <jgrimm@us.ibm.com>
 *    Sridhar Samudrala <sri@us.ibm.com>
 *    Daisy Chang <daisyc@us.ibm.com>
 *    Ardelle Fan <ardelle.fan@intel.com>
 *
 * Any bugs reported given to us we will try to fix... any fixes shared will
 * be incorporated into the next SCTP release.
 */

#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 <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;
DEFINE_SNMP_STAT(struct sctp_mib, sctp_statistics) __read_mostly;

#ifdef CONFIG_PROC_FS
struct proc_dir_entry   *proc_net_sctp;
#endif

struct idr sctp_assocs_id;
DEFINE_SPINLOCK(sctp_assocs_id_lock);

/* This is the global socket data structure used for responding to
 * the Out-of-the-blue (OOTB) packets.  A control sock will be created
 * for this socket at the initialization time.
 */
static struct sock *sctp_ctl_sock;

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;

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

/* Return the address of the control sock. */
struct sock *sctp_get_ctl_sock(void)
{
        return sctp_ctl_sock;
}

/* Set up the proc fs entry for the SCTP protocol. */
static __init int sctp_proc_init(void)
{
        if (percpu_counter_init(&sctp_sockets_allocated, 0))
                goto out_nomem;
#ifdef CONFIG_PROC_FS
        if (!proc_net_sctp) {
                struct proc_dir_entry *ent;
                ent = proc_mkdir("sctp", init_net.proc_net);
                if (ent) {
                        ent->owner = THIS_MODULE;
                        proc_net_sctp = ent;
                } else
                        goto out_free_percpu;
        }

        if (sctp_snmp_proc_init())
                goto out_snmp_proc_init;
        if (sctp_eps_proc_init())
                goto out_eps_proc_init;
        if (sctp_assocs_proc_init())
                goto out_assocs_proc_init;
        if (sctp_remaddr_proc_init())
                goto out_remaddr_proc_init;

        return 0;

out_remaddr_proc_init:
        sctp_assocs_proc_exit();
out_assocs_proc_init:
        sctp_eps_proc_exit();
out_eps_proc_init:
        sctp_snmp_proc_exit();
out_snmp_proc_init:
        if (proc_net_sctp) {
                proc_net_sctp = NULL;
                remove_proc_entry("sctp", init_net.proc_net);
        }
out_free_percpu:
        percpu_counter_destroy(&sctp_sockets_allocated);
#else
        return 0;
#endif /* CONFIG_PROC_FS */

out_nomem:
        return -ENOMEM;
}

/* 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(void)
{
#ifdef CONFIG_PROC_FS
        sctp_snmp_proc_exit();
        sctp_eps_proc_exit();
        sctp_assocs_proc_exit();
        sctp_remaddr_proc_exit();

        if (proc_net_sctp) {
                proc_net_sctp = NULL;
                remove_proc_entry("sctp", init_net.proc_net);
        }
#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);
                        INIT_RCU_HEAD(&addr->rcu);
                        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(void)
{
        struct net_device *dev;
        struct list_head *pos;
        struct sctp_af *af;

        read_lock(&dev_base_lock);
        for_each_netdev(&init_net, dev) {
                __list_for_each(pos, &sctp_address_families) {
                        af = list_entry(pos, struct sctp_af, list);
                        af->copy_addrlist(&sctp_local_addr_list, dev);
                }
        }
        read_unlock(&dev_base_lock);
}

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

        list_for_each_safe(pos, temp, &sctp_local_addr_list) {
                addr = list_entry(pos, struct sctp_sockaddr_entry, list);
                list_del(pos);
                kfree(addr);
        }
}

void sctp_local_addr_free(struct rcu_head *head)
{
        struct sctp_sockaddr_entry *e = container_of(head,
                                struct sctp_sockaddr_entry, rcu);
        kfree(e);
}

/* Copy the local addresses which are valid for 'scope' into 'bp'.  */
int sctp_copy_local_addr_list(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, &sctp_local_addr_list, list) {
                if (!addr->valid)
                        continue;
                if (sctp_in_scope(&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)->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)->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)->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 dst_entry *dst,
                              __be16 port)
{
        struct rtable *rt = (struct rtable *)dst;
        saddr->v4.sin_family = AF_INET;
        saddr->v4.sin_port = port;
        saddr->v4.sin_addr.s_addr = rt->rt_src;
}

/* 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->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)
{
        int ret = inet_addr_type(&init_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.
 */
static sctp_scope_t sctp_v4_scope(union sctp_addr *addr)
{
        sctp_scope_t retval;

        /* Should IPv4 scoping be a sysctl configurable option
         * so users can turn it off (default on) for certain
         * unconventional networking environments?
         */

        /* 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 struct dst_entry *sctp_v4_get_dst(struct sctp_association *asoc,
                                         union sctp_addr *daddr,
                                         union sctp_addr *saddr)
{
        struct rtable *rt;
        struct flowi fl;
        struct sctp_bind_addr *bp;
        struct sctp_sockaddr_entry *laddr;
        struct dst_entry *dst = NULL;
        union sctp_addr dst_saddr;

        memset(&fl, 0x0, sizeof(struct flowi));
        fl.fl4_dst  = daddr->v4.sin_addr.s_addr;
        fl.proto = IPPROTO_SCTP;
        if (asoc) {
                fl.fl4_tos = RT_CONN_FLAGS(asoc->base.sk);
                fl.oif = asoc->base.sk->sk_bound_dev_if;
        }
        if (saddr)
                fl.fl4_src = saddr->v4.sin_addr.s_addr;

        SCTP_DEBUG_PRINTK("%s: DST:%pI4, SRC:%pI4 - ",
                          __func__, &fl.fl4_dst, &fl.fl4_src);

        if (!ip_route_output_key(&init_net, &rt, &fl)) {
                dst = &rt->u.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, dst, htons(bp->port));
                rcu_read_lock();
                list_for_each_entry_rcu(laddr, &bp->address_list, list) {
                        if (!laddr->valid || (laddr->state != SCTP_ADDR_SRC))
                                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)) {
                        fl.fl4_src = laddr->a.v4.sin_addr.s_addr;
                        if (!ip_route_output_key(&init_net, &rt, &fl)) {
                                dst = &rt->u.dst;
                                goto out_unlock;
                        }
                }
        }

out_unlock:
        rcu_read_unlock();
out:
        if (dst)
                SCTP_DEBUG_PRINTK("rt_dst:%pI4, rt_src:%pI4\n",
                                  &rt->rt_dst, &rt->rt_src);
        else
                SCTP_DEBUG_PRINTK("NO ROUTE\n");

        return dst;
}

/* 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_association *asoc,
                              struct dst_entry *dst,
                              union sctp_addr *daddr,
                              union sctp_addr *saddr)
{
        struct rtable *rt = (struct rtable *)dst;

        if (!asoc)
                return;

        if (rt) {
                saddr->v4.sin_family = AF_INET;
                saddr->v4.sin_port = htons(asoc->base.bind_addr.port);
                saddr->v4.sin_addr.s_addr = rt->rt_src;
        }
}

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

/* 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 inet_sock *inet = inet_sk(sk);
        struct inet_sock *newinet;
        struct sock *newsk = sk_alloc(sock_net(sk), PF_INET, GFP_KERNEL,
                        sk->sk_prot);

        if (!newsk)
                goto out;

        sock_init_data(NULL, newsk);

        newsk->sk_type = SOCK_STREAM;

        newsk->sk_no_check = sk->sk_no_check;
        newsk->sk_reuse = sk->sk_reuse;
        newsk->sk_shutdown = sk->sk_shutdown;

        newsk->sk_destruct = inet_sock_destruct;
        newsk->sk_family = PF_INET;
        newsk->sk_protocol = IPPROTO_SCTP;
        newsk->sk_backlog_rcv = sk->sk_prot->backlog_rcv;
        sock_reset_flag(newsk, SOCK_ZAPPED);

        newinet = inet_sk(newsk);

        /* Initialize sk's sport, dport, rcv_saddr and daddr for
         * getsockname() and getpeername()
         */
        newinet->sport = inet->sport;
        newinet->saddr = inet->saddr;
        newinet->rcv_saddr = inet->rcv_saddr;
        newinet->dport = htons(asoc->peer.port);
        newinet->daddr = asoc->peer.primary_addr.v4.sin_addr.s_addr;
        newinet->pmtudisc = inet->pmtudisc;
        newinet->id = asoc->next_tsn ^ jiffies;

        newinet->uc_ttl = -1;
        newinet->mc_loop = 1;
        newinet->mc_ttl = 1;
        newinet->mc_index = 0;
        newinet->mc_list = NULL;

        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);
}

/* 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;
        int found = 0;

        if (!net_eq(dev_net(ifa->ifa_dev->dev), &init_net))
                return NOTIFY_DONE;

        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(&sctp_local_addr_lock);
                        list_add_tail_rcu(&addr->list, &sctp_local_addr_list);
                        spin_unlock_bh(&sctp_local_addr_lock);
                }
                break;
        case NETDEV_DOWN:
                spin_lock_bh(&sctp_local_addr_lock);
                list_for_each_entry_safe(addr, temp,
                                        &sctp_local_addr_list, list) {
                        if (addr->a.sa.sa_family == AF_INET &&
                                        addr->a.v4.sin_addr.s_addr ==
                                        ifa->ifa_local) {
                                found = 1;
                                addr->valid = 0;
                                list_del_rcu(&addr->list);
                                break;
                        }
                }
                spin_unlock_bh(&sctp_local_addr_lock);
                if (found)
                        call_rcu(&addr->rcu, sctp_local_addr_free);
                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(void)
{
        int err;
        sa_family_t family = PF_INET;

        if (sctp_get_pf_specific(PF_INET6))
                family = PF_INET6;

        err = inet_ctl_sock_create(&sctp_ctl_sock, family,
                                   SOCK_SEQPACKET, IPPROTO_SCTP, &init_net);

        /* If IPv6 socket could not be created, try the IPv4 socket */
        if (err < 0 && family == PF_INET6)
                err = inet_ctl_sock_create(&sctp_ctl_sock, AF_INET,
                                           SOCK_SEQPACKET, IPPROTO_SCTP,
                                           &init_net);

        if (err < 0) {
                printk(KERN_ERR
                       "SCTP: 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,
                          &skb->rtable->rt_src,
                          &skb->rtable->rt_dst);

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

        SCTP_INC_STATS(SCTP_MIB_OUTSCTPPACKS);
        return ip_queue_xmit(skb, 0);
}

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,
        .capability = -1,
        .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,
        .capability = -1,
        .no_check   = 0,
        .flags      = SCTP_PROTOSW_FLAG
};

/* Register with IP layer.  */
static struct net_protocol sctp_protocol = {
        .handler     = sctp_rcv,
        .err_handler = sctp_v4_err,
        .no_policy   = 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,
        .dst_saddr         = sctp_v4_dst_saddr,
        .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(void)
{
        return snmp_mib_init((void**)sctp_statistics, sizeof(struct sctp_mib));
}

static inline void cleanup_sctp_mibs(void)
{
        snmp_mib_free((void**)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);
}

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

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

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

        /* Initialize object count debugging.  */
        sctp_dbg_objcnt_init();

        /*
         * 14. Suggested SCTP Protocol Parameter Values
         */
        /* The following protocol parameters are RECOMMENDED:  */
        /* RTO.Initial              - 3  seconds */
        sctp_rto_initial                = SCTP_RTO_INITIAL;
        /* RTO.Min                  - 1  second */
        sctp_rto_min                    = SCTP_RTO_MIN;
        /* RTO.Max                 -  60 seconds */
        sctp_rto_max                    = SCTP_RTO_MAX;
        /* RTO.Alpha                - 1/8 */
        sctp_rto_alpha                  = SCTP_RTO_ALPHA;
        /* RTO.Beta                 - 1/4 */
        sctp_rto_beta                   = SCTP_RTO_BETA;

        /* Valid.Cookie.Life        - 60  seconds */
        sctp_valid_cookie_life          = SCTP_DEFAULT_COOKIE_LIFE;

        /* Whether Cookie Preservative is enabled(1) or not(0) */
        sctp_cookie_preserve_enable     = 1;

        /* Max.Burst                - 4 */
        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
         */
        sctp_max_retrans_association    = 10;
        sctp_max_retrans_path           = 5;
        sctp_max_retrans_init           = 8;

        /* Sendbuffer growth        - do per-socket accounting */
        sctp_sndbuf_policy              = 0;

        /* Rcvbuffer growth         - do per-socket accounting */
        sctp_rcvbuf_policy              = 0;

        /* HB.interval              - 30 seconds */
        sctp_hb_interval                = SCTP_DEFAULT_TIMEOUT_HEARTBEAT;

        /* delayed SACK timeout */
        sctp_sack_timeout               = SCTP_DEFAULT_TIMEOUT_SACK;

        /* 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);

        /* Set the pressure threshold to be a fraction of global memory that
         * is up to 1/2 at 256 MB, decreasing toward zero with the amount of
         * memory, with a floor of 128 pages.
         * Note this initalizes the data in sctpv6_prot too
         * Unabashedly stolen from tcp_init
         */
        nr_pages = totalram_pages - totalhigh_pages;
        limit = min(nr_pages, 1UL<<(28-PAGE_SHIFT)) >> (20-PAGE_SHIFT);
        limit = (limit * (nr_pages >> (20-PAGE_SHIFT))) >> (PAGE_SHIFT-11);
        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 *(sizeof(struct sk_buff) + 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 (num_physpages >= (128 * 1024))
                goal = num_physpages >> (22 - PAGE_SHIFT);
        else
                goal = num_physpages >> (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, order);
        } while (!sctp_assoc_hashtable && --order > 0);
        if (!sctp_assoc_hashtable) {
                printk(KERN_ERR "SCTP: 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) {
                printk(KERN_ERR "SCTP: 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, order);
        } while (!sctp_port_hashtable && --order > 0);
        if (!sctp_port_hashtable) {
                printk(KERN_ERR "SCTP: Failed bind hash alloc.");
                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);
        }

        printk(KERN_INFO "SCTP: Hash tables configured "
                         "(established %d bind %d)\n",
                sctp_assoc_hashsize, sctp_port_hashsize);

        /* Disable ADDIP by default. */
        sctp_addip_enable = 0;
        sctp_addip_noauth = 0;

        /* Enable PR-SCTP by default. */
        sctp_prsctp_enable = 1;

        /* Disable AUTH by default. */
        sctp_auth_enable = 0;

        sctp_sysctl_register();

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

        /* Initialize the local address list. */
        INIT_LIST_HEAD(&sctp_local_addr_list);
        spin_lock_init(&sctp_local_addr_lock);
        sctp_get_local_addr_list();

        status = sctp_v4_protosw_init();

        if (status)
                goto err_protosw_init;

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

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

        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:
        inet_ctl_sock_destroy(sctp_ctl_sock);
err_ctl_sock_init:
        sctp_v6_protosw_exit();
err_v6_protosw_init:
        sctp_v4_protosw_exit();
err_protosw_init:
        sctp_free_local_addr_list();
        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:
        sctp_dbg_objcnt_exit();
        sctp_proc_exit();
err_init_proc:
        cleanup_sctp_mibs();
err_init_mibs:
        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();

        /* Free the control endpoint.  */
        inet_ctl_sock_destroy(sctp_ctl_sock);

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

        /* Free the local address list.  */
        sctp_free_local_addr_list();

        /* 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)));

        sctp_dbg_objcnt_exit();
        sctp_proc_exit();
        cleanup_sctp_mibs();

        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 <lksctp-developers@lists.sourceforge.net>");
MODULE_DESCRIPTION("Support for the SCTP protocol (RFC2960)");
MODULE_LICENSE("GPL");