Merge tag 'trace-v5.11-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt...

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

// SPDX-License-Identifier: GPL-2.0-or-later
/* 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.
 *
 * Please send any bug reports or fixes you make to the
 * email address(es):
 *    lksctp developers <linux-sctp@vger.kernel.org>
 *
 * 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>
 */

#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/memblock.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>
#include <net/udp_tunnel.h>

#define MAX_SCTP_PORT_HASH_ENTRIES (64 * 1024)

/* 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];

/* 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;
        }

        in_dev_for_each_ifa_rcu(ifa, in_dev) {
                /* Add the address to the local list.  */
                addr = kzalloc(sizeof(*addr), GFP_ATOMIC);
                if (addr) {
                        addr->a.v4.sin_family = AF_INET;
                        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,
                              enum sctp_scope scope, gfp_t gfp, int copy_flags)
{
        struct sctp_sockaddr_entry *addr;
        union sctp_addr laddr;
        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))
                        continue;

                /* 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 (addr->a.sa.sa_family == AF_INET &&
                    (!(copy_flags & SCTP_ADDR4_ALLOWED) ||
                     !(copy_flags & SCTP_ADDR4_PEERSUPP)))
                        continue;
                if (addr->a.sa.sa_family == AF_INET6 &&
                    (!(copy_flags & SCTP_ADDR6_ALLOWED) ||
                     !(copy_flags & SCTP_ADDR6_PEERSUPP)))
                        continue;

                laddr = addr->a;
                /* also works for setting ipv6 address port */
                laddr.v4.sin_port = htons(bp->port);
                if (sctp_bind_addr_state(bp, &laddr) != -1)
                        continue;

                error = sctp_add_bind_addr(bp, &addr->a, sizeof(addr->a),
                                           SCTP_ADDR_SRC, GFP_ATOMIC);
                if (error)
                        break;
        }

        rcu_read_unlock();
        return error;
}

/* Copy over any ip options */
static void sctp_v4_copy_ip_options(struct sock *sk, struct sock *newsk)
{
        struct inet_sock *newinet, *inet = inet_sk(sk);
        struct ip_options_rcu *inet_opt, *newopt = NULL;

        newinet = inet_sk(newsk);

        rcu_read_lock();
        inet_opt = rcu_dereference(inet->inet_opt);
        if (inet_opt) {
                newopt = sock_kmalloc(newsk, sizeof(*inet_opt) +
                                      inet_opt->opt.optlen, GFP_ATOMIC);
                if (newopt)
                        memcpy(newopt, inet_opt, sizeof(*inet_opt) +
                               inet_opt->opt.optlen);
                else
                        pr_err("%s: Failed to copy ip options\n", __func__);
        }
        RCU_INIT_POINTER(newinet->inet_opt, newopt);
        rcu_read_unlock();
}

/* Account for the IP options */
static int sctp_v4_ip_options_len(struct sock *sk)
{
        struct inet_sock *inet = inet_sk(sk);
        struct ip_options_rcu *inet_opt;
        int len = 0;

        rcu_read_lock();
        inet_opt = rcu_dereference(inet->inet_opt);
        if (inet_opt)
                len = inet_opt->opt.optlen;

        rcu_read_unlock();
        return len;
}

/* 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)
{
        /* Always called on head skb, so this is safe */
        struct sctphdr *sh = sctp_hdr(skb);
        struct sockaddr_in *sa = &addr->v4;

        addr->v4.sin_family = AF_INET;

        if (is_saddr) {
                sa->sin_port = sh->source;
                sa->sin_addr.s_addr = ip_hdr(skb)->saddr;
        } else {
                sa->sin_port = sh->dest;
                sa->sin_addr.s_addr = ip_hdr(skb)->daddr;
        }
        memset(sa->sin_zero, 0, sizeof(sa->sin_zero));
}

/* 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;
        memset(addr->v4.sin_zero, 0, sizeof(addr->v4.sin_zero));
}

/* 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;
        memset(addr->v4.sin_zero, 0, sizeof(addr->v4.sin_zero));
}

/* 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(struct sctp_ipv4addr_param);

        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;
        memset(saddr->v4.sin_zero, 0, sizeof(saddr->v4.sin_zero));
}

/* 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;
        memset(addr->v4.sin_zero, 0, sizeof(addr->v4.sin_zero));
}

/* 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 &&
           !net->ipv4.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
 * 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 enum sctp_scope sctp_v4_scope(union sctp_addr *addr)
{
        enum sctp_scope 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 flowi _fl;
        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;
        __u8 tos = inet_sk(sk)->tos;

        if (t->dscp & SCTP_DSCP_SET_MASK)
                tos = t->dscp & SCTP_DSCP_VAL_MASK;
        memset(&_fl, 0x0, sizeof(_fl));
        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_TOS(asoc->base.sk, tos);
                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;
                if (!fl4->fl4_sport)
                        fl4->fl4_sport = saddr->v4.sin_port;
        }

        pr_debug("%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;
                t->dst = dst;
                memcpy(fl, &_fl, sizeof(_fl));
        }

        /* 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) {
                struct net_device *odev;

                if (!laddr->valid)
                        continue;
                if (laddr->state != SCTP_ADDR_SRC ||
                    AF_INET != laddr->a.sa.sa_family)
                        continue;

                fl4->fl4_sport = laddr->a.v4.sin_port;
                flowi4_update_output(fl4,
                                     asoc->base.sk->sk_bound_dev_if,
                                     RT_CONN_FLAGS_TOS(asoc->base.sk, tos),
                                     daddr->v4.sin_addr.s_addr,
                                     laddr->a.v4.sin_addr.s_addr);

                rt = ip_route_output_key(sock_net(sk), fl4);
                if (IS_ERR(rt))
                        continue;

                /* Ensure the src address belongs to the output
                 * interface.
                 */
                odev = __ip_dev_find(sock_net(sk), laddr->a.v4.sin_addr.s_addr,
                                     false);
                if (!odev || odev->ifindex != fl4->flowi4_oif) {
                        if (!dst) {
                                dst = &rt->dst;
                                t->dst = dst;
                                memcpy(fl, &_fl, sizeof(_fl));
                        } else {
                                dst_release(&rt->dst);
                        }
                        continue;
                }

                dst_release(dst);
                dst = &rt->dst;
                t->dst = dst;
                memcpy(fl, &_fl, sizeof(_fl));
                break;
        }

out_unlock:
        rcu_read_unlock();
out:
        if (dst) {
                pr_debug("rt_dst:%pI4, rt_src:%pI4\n",
                         &fl->u.ip4.daddr, &fl->u.ip4.saddr);
        } else {
                t->dst = NULL;
                pr_debug("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,
                                             bool kern)
{
        struct sock *newsk = sk_alloc(sock_net(sk), PF_INET, GFP_KERNEL,
                        sk->sk_prot, kern);
        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);

        sctp_v4_copy_ip_options(sk, newsk);

        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;
}

static int sctp_v4_addr_to_user(struct sctp_sock *sp, union sctp_addr *addr)
{
        /* No address mapping for V4 sockets */
        memset(addr->v4.sin_zero, 0, sizeof(addr->v4.sin_zero));
        return sizeof(struct sockaddr_in);
}

/* 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);
}

static void sctp_addr_wq_timeout_handler(struct timer_list *t)
{
        struct net *net = from_timer(net, t, sctp.addr_wq_timer);
        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) {
                pr_debug("%s: the first ent in wq:%p is addr:%pISc for cmd:%d at "
                         "entry:%p\n", __func__, &net->sctp.addr_waitq, &addrw->a.sa,
                         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;

                                pr_debug("%s: this is on DAD, trying %d sec "
                                         "later\n", __func__,
                                         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;
                        bh_lock_sock(sk);
                        if (sctp_asconf_mgmt(sp, addrw) < 0)
                                pr_debug("%s: sctp_asconf_mgmt failed\n", __func__);
                        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) {
                        pr_debug("%s: offsets existing entry for %d, addr:%pISc "
                                 "in wq:%p\n", __func__, addrw->state, &addrw->a.sa,
                                 &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);

        pr_debug("%s: add new entry for cmd:%d, addr:%pISc in wq:%p\n",
                 __func__, addrw->state, &addrw->a.sa, &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 = kzalloc(sizeof(*addr), GFP_ATOMIC);
                if (addr) {
                        addr->a.v4.sin_family = AF_INET;
                        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;
}

static int sctp_udp_rcv(struct sock *sk, struct sk_buff *skb)
{
        SCTP_INPUT_CB(skb)->encap_port = udp_hdr(skb)->source;

        skb_set_transport_header(skb, sizeof(struct udphdr));
        sctp_rcv(skb);
        return 0;
}

static int sctp_udp_err_lookup(struct sock *sk, struct sk_buff *skb)
{
        struct sctp_association *asoc;
        struct sctp_transport *t;
        int family;

        skb->transport_header += sizeof(struct udphdr);
        family = (ip_hdr(skb)->version == 4) ? AF_INET : AF_INET6;
        sk = sctp_err_lookup(dev_net(skb->dev), family, skb, sctp_hdr(skb),
                             &asoc, &t);
        if (!sk)
                return -ENOENT;

        sctp_err_finish(sk, t);
        return 0;
}

int sctp_udp_sock_start(struct net *net)
{
        struct udp_tunnel_sock_cfg tuncfg = {NULL};
        struct udp_port_cfg udp_conf = {0};
        struct socket *sock;
        int err;

        udp_conf.family = AF_INET;
        udp_conf.local_ip.s_addr = htonl(INADDR_ANY);
        udp_conf.local_udp_port = htons(net->sctp.udp_port);
        err = udp_sock_create(net, &udp_conf, &sock);
        if (err) {
                pr_err("Failed to create the SCTP UDP tunneling v4 sock\n");
                return err;
        }

        tuncfg.encap_type = 1;
        tuncfg.encap_rcv = sctp_udp_rcv;
        tuncfg.encap_err_lookup = sctp_udp_err_lookup;
        setup_udp_tunnel_sock(net, sock, &tuncfg);
        net->sctp.udp4_sock = sock->sk;

#if IS_ENABLED(CONFIG_IPV6)
        memset(&udp_conf, 0, sizeof(udp_conf));

        udp_conf.family = AF_INET6;
        udp_conf.local_ip6 = in6addr_any;
        udp_conf.local_udp_port = htons(net->sctp.udp_port);
        udp_conf.use_udp6_rx_checksums = true;
        udp_conf.ipv6_v6only = true;
        err = udp_sock_create(net, &udp_conf, &sock);
        if (err) {
                pr_err("Failed to create the SCTP UDP tunneling v6 sock\n");
                udp_tunnel_sock_release(net->sctp.udp4_sock->sk_socket);
                net->sctp.udp4_sock = NULL;
                return err;
        }

        tuncfg.encap_type = 1;
        tuncfg.encap_rcv = sctp_udp_rcv;
        tuncfg.encap_err_lookup = sctp_udp_err_lookup;
        setup_udp_tunnel_sock(net, sock, &tuncfg);
        net->sctp.udp6_sock = sock->sk;
#endif

        return 0;
}

void sctp_udp_sock_stop(struct net *net)
{
        if (net->sctp.udp4_sock) {
                udp_tunnel_sock_release(net->sctp.udp4_sock->sk_socket);
                net->sctp.udp4_sock = NULL;
        }
        if (net->sctp.udp6_sock) {
                udp_tunnel_sock_release(net->sctp.udp6_sock->sk_socket);
                net->sctp.udp6_sock = NULL;
        }
}

/* 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 *t)
{
        struct dst_entry *dst = dst_clone(t->dst);
        struct flowi4 *fl4 = &t->fl.u.ip4;
        struct sock *sk = skb->sk;
        struct inet_sock *inet = inet_sk(sk);
        __u8 dscp = inet->tos;
        __be16 df = 0;

        pr_debug("%s: skb:%p, len:%d, src:%pI4, dst:%pI4\n", __func__, skb,
                 skb->len, &fl4->saddr, &fl4->daddr);

        if (t->dscp & SCTP_DSCP_SET_MASK)
                dscp = t->dscp & SCTP_DSCP_VAL_MASK;

        inet->pmtudisc = t->param_flags & SPP_PMTUD_ENABLE ? IP_PMTUDISC_DO
                                                           : IP_PMTUDISC_DONT;
        SCTP_INC_STATS(sock_net(sk), SCTP_MIB_OUTSCTPPACKS);

        if (!t->encap_port || !sctp_sk(sk)->udp_port) {
                skb_dst_set(skb, dst);
                return __ip_queue_xmit(sk, skb, &t->fl, dscp);
        }

        if (skb_is_gso(skb))
                skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;

        if (ip_dont_fragment(sk, dst) && !skb->ignore_df)
                df = htons(IP_DF);

        skb->encapsulation = 1;
        skb_reset_inner_mac_header(skb);
        skb_reset_inner_transport_header(skb);
        skb_set_inner_ipproto(skb, IPPROTO_SCTP);
        udp_tunnel_xmit_skb((struct rtable *)dst, sk, skb, fl4->saddr,
                            fl4->daddr, dscp, ip4_dst_hoplimit(dst), df,
                            sctp_sk(sk)->udp_port, t->encap_port, false, false);
        return 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_to_user  = sctp_v4_addr_to_user,
        .to_sk_saddr   = sctp_v4_to_sk_saddr,
        .to_sk_daddr   = sctp_v4_to_sk_daddr,
        .copy_ip_options = sctp_v4_copy_ip_options,
        .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           = sctp_inet_connect,
        .socketpair        = sock_no_socketpair,
        .accept            = inet_accept,
        .getname           = inet_getname,      /* Semantics are different.  */
        .poll              = sctp_poll,
        .ioctl             = inet_ioctl,
        .gettstamp         = sock_gettstamp,
        .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           = inet_recvmsg,
        .mmap              = sock_no_mmap,
        .sendpage          = sock_no_sendpage,
};

/* 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,
        .flags      = SCTP_PROTOSW_FLAG
};
static struct inet_protosw sctp_stream_protosw = {
        .type       = SOCK_STREAM,
        .protocol   = IPPROTO_SCTP,
        .prot       = &sctp_prot,
        .ops        = &inet_seqpacket_ops,
        .flags      = SCTP_PROTOSW_FLAG
};

static int sctp4_rcv(struct sk_buff *skb)
{
        SCTP_INPUT_CB(skb)->encap_port = 0;
        return sctp_rcv(skb);
}

/* Register with IP layer.  */
static const struct net_protocol sctp_protocol = {
        .handler     = sctp4_rcv,
        .err_handler = sctp_v4_err,
        .no_policy   = 1,
        .netns_ok    = 1,
        .icmp_strict_tag_validation = 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,
        .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),
        .ip_options_len    = sctp_v4_ip_options_len,
};

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)
{
        net->sctp.sctp_statistics = alloc_percpu(struct sctp_mib);
        if (!net->sctp.sctp_statistics)
                return -ENOMEM;
        return 0;
}

static inline void cleanup_sctp_mibs(struct net *net)
{
        free_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 __net_init sctp_defaults_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;

        /* Default sctp sockets to use md5 as their hmac alg */
#if defined (CONFIG_SCTP_DEFAULT_COOKIE_HMAC_MD5)
        net->sctp.sctp_hmac_alg                 = "md5";
#elif defined (CONFIG_SCTP_DEFAULT_COOKIE_HMAC_SHA1)
        net->sctp.sctp_hmac_alg                 = "sha1";
#else
        net->sctp.sctp_hmac_alg                 = NULL;
#endif

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

        /* Disable of Primary Path Switchover by default */
        net->sctp.ps_retrans = SCTP_PS_RETRANS_MAX;

        /* Enable pf state by default */
        net->sctp.pf_enable = 1;

        /* Ignore pf exposure feature by default */
        net->sctp.pf_expose = SCTP_PF_EXPOSE_UNSET;

        /* 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 RECONF by default. */
        net->sctp.reconf_enable = 0;

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

        /* Enable ECN by default. */
        net->sctp.ecn_enable = 1;

        /* Set UDP tunneling listening port to 0 by default */
        net->sctp.udp_port = 0;

        /* Set remote encap port to 0 by default */
        net->sctp.encap_port = 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;

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

        sctp_dbg_objcnt_init(net);

        /* 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;
        timer_setup(&net->sctp.addr_wq_timer, sctp_addr_wq_timeout_handler, 0);

        return 0;

#ifdef CONFIG_PROC_FS
err_init_proc:
        cleanup_sctp_mibs(net);
#endif
err_init_mibs:
        sctp_sysctl_net_unregister(net);
err_sysctl_register:
        return status;
}

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

#ifdef CONFIG_PROC_FS
        remove_proc_subtree("sctp", net->proc_net);
        net->sctp.proc_net_sctp = NULL;
#endif
        cleanup_sctp_mibs(net);
        sctp_sysctl_net_unregister(net);
}

static struct pernet_operations sctp_defaults_ops = {
        .init = sctp_defaults_init,
        .exit = sctp_defaults_exit,
};

static int __net_init sctp_ctrlsock_init(struct net *net)
{
        int status;

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

        return status;
}

static void __net_exit sctp_ctrlsock_exit(struct net *net)
{
        /* Free the control endpoint.  */
        inet_ctl_sock_destroy(net->sctp.ctl_sock);
}

static struct pernet_operations sctp_ctrlsock_ops = {
        .init = sctp_ctrlsock_init,
        .exit = sctp_ctrlsock_exit,
};

/* Initialize the universe into something sensible.  */
static __init int sctp_init(void)
{
        unsigned long nr_pages = totalram_pages();
        unsigned long limit;
        unsigned long goal;
        int max_entry_order;
        int num_entries;
        int max_share;
        int status;
        int order;
        int i;

        sock_skb_cb_check_size(sizeof(struct sctp_ulpevent));

        /* 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, GFP_KERNEL);
        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.
         * Though not identical.  Start by getting a goal size
         */
        if (nr_pages >= (128 * 1024))
                goal = nr_pages >> (22 - PAGE_SHIFT);
        else
                goal = nr_pages >> (24 - PAGE_SHIFT);

        /* Then compute the page order for said goal */
        order = get_order(goal);

        /* Now compute the required page order for the maximum sized table we
         * want to create
         */
        max_entry_order = get_order(MAX_SCTP_PORT_HASH_ENTRIES *
                                    sizeof(struct sctp_bind_hashbucket));

        /* Limit the page order by that maximum hash table size */
        order = min(order, max_entry_order);

        /* Allocate and initialize the endpoint hash table.  */
        sctp_ep_hashsize = 64;
        sctp_ep_hashtable =
                kmalloc_array(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.
         * Note that order is initalized to start at the max sized
         * table we want to support.  If we can't get that many pages
         * reduce the order and try again
         */
        do {
                sctp_port_hashtable = (struct sctp_bind_hashbucket *)
                        __get_free_pages(GFP_KERNEL | __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;
        }

        /* Now compute the number of entries that will fit in the
         * port hash space we allocated
         */
        num_entries = (1UL << order) * PAGE_SIZE /
                      sizeof(struct sctp_bind_hashbucket);

        /* And finish by rounding it down to the nearest power of two.
         * This wastes some memory of course, but it's needed because
         * the hash function operates based on the assumption that
         * the number of entries is a power of two.
         */
        sctp_port_hashsize = rounddown_pow_of_two(num_entries);

        for (i = 0; i < sctp_port_hashsize; i++) {
                spin_lock_init(&sctp_port_hashtable[i].lock);
                INIT_HLIST_HEAD(&sctp_port_hashtable[i].chain);
        }

        status = sctp_transport_hashtable_init();
        if (status)
                goto err_thash_alloc;

        pr_info("Hash tables configured (bind %d/%d)\n", sctp_port_hashsize,
                num_entries);

        sctp_sysctl_register();

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

        status = register_pernet_subsys(&sctp_defaults_ops);
        if (status)
                goto err_register_defaults;

        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_ctrlsock_ops);
        if (status)
                goto err_register_ctrlsock;

        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;

        if (sctp_offload_init() < 0)
                pr_crit("%s: Cannot add SCTP protocol offload\n", __func__);

out:
        return status;
err_v6_add_protocol:
        sctp_v4_del_protocol();
err_add_protocol:
        unregister_pernet_subsys(&sctp_ctrlsock_ops);
err_register_ctrlsock:
        sctp_v6_protosw_exit();
err_v6_protosw_init:
        sctp_v4_protosw_exit();
err_protosw_init:
        unregister_pernet_subsys(&sctp_defaults_ops);
err_register_defaults:
        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:
        sctp_transport_hashtable_destroy();
err_thash_alloc:
        kfree(sctp_ep_hashtable);
err_ehash_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.  */
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_ctrlsock_ops);

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

        unregister_pernet_subsys(&sctp_defaults_ops);

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

        sctp_sysctl_unregister();

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

        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 <linux-sctp@vger.kernel.org>");
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");