// SPDX-License-Identifier: GPL-2.0-or-later
/* SCTP kernel implementation
 * (C) Copyright IBM Corp. 2002, 2004
 * Copyright (c) 2001 Nokia, Inc.
 * Copyright (c) 2001 La Monte H.P. Yarroll
 * Copyright (c) 2002-2003 Intel Corp.
 *
 * This file is part of the SCTP kernel implementation
 *
 * SCTP over IPv6.
 *
 * 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:
 *    Le Yanqun             <yanqun.le@nokia.com>
 *    Hui Huang             <hui.huang@nokia.com>
 *    La Monte H.P. Yarroll <piggy@acm.org>
 *    Sridhar Samudrala     <sri@us.ibm.com>
 *    Jon Grimm             <jgrimm@us.ibm.com>
 *    Ardelle Fan           <ardelle.fan@intel.com>
 *
 * Based on:
 *      linux/net/ipv6/tcp_ipv6.c
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/netdevice.h>
#include <linux/init.h>
#include <linux/ipsec.h>
#include <linux/slab.h>

#include <linux/ipv6.h>
#include <linux/icmpv6.h>
#include <linux/random.h>
#include <linux/seq_file.h>

#include <net/protocol.h>
#include <net/ndisc.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <net/transp_v6.h>
#include <net/addrconf.h>
#include <net/ip6_route.h>
#include <net/inet_common.h>
#include <net/inet_ecn.h>
#include <net/sctp/sctp.h>
#include <net/udp_tunnel.h>

#include <linux/uaccess.h>

static inline int sctp_v6_addr_match_len(union sctp_addr *s1,
                                         union sctp_addr *s2);
static void sctp_v6_to_addr(union sctp_addr *addr, struct in6_addr *saddr,
                              __be16 port);
static int sctp_v6_cmp_addr(const union sctp_addr *addr1,
                            const union sctp_addr *addr2);

/* Event handler for inet6 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_inet6addr_event(struct notifier_block *this, unsigned long ev,
                                void *ptr)
{
        struct inet6_ifaddr *ifa = (struct inet6_ifaddr *)ptr;
        struct sctp_sockaddr_entry *addr = NULL;
        struct sctp_sockaddr_entry *temp;
        struct net *net = dev_net(ifa->idev->dev);
        int found = 0;

        switch (ev) {
        case NETDEV_UP:
                addr = kzalloc_obj(*addr, GFP_ATOMIC);
                if (addr) {
                        addr->a.v6.sin6_family = AF_INET6;
                        addr->a.v6.sin6_addr = ifa->addr;
                        addr->a.v6.sin6_scope_id = ifa->idev->dev->ifindex;
                        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_INET6 &&
                            ipv6_addr_equal(&addr->a.v6.sin6_addr,
                                            &ifa->addr) &&
                            addr->a.v6.sin6_scope_id == ifa->idev->dev->ifindex) {
                                found = 1;
                                addr->valid = 0;
                                list_del_rcu(&addr->list);
                                sctp_addr_wq_mgmt(net, addr, SCTP_ADDR_DEL);
                                break;
                        }
                }
                spin_unlock_bh(&net->sctp.local_addr_lock);
                if (found)
                        kfree_rcu(addr, rcu);
                break;
        }

        return NOTIFY_DONE;
}

static struct notifier_block sctp_inet6addr_notifier = {
        .notifier_call = sctp_inet6addr_event,
};

static void sctp_v6_err_handle(struct sctp_transport *t, struct sk_buff *skb,
                               __u8 type, __u8 code, __u32 info)
{
        struct sctp_association *asoc = t->asoc;
        struct sock *sk = asoc->base.sk;
        int err = 0;

        switch (type) {
        case ICMPV6_PKT_TOOBIG:
                if (ip6_sk_accept_pmtu(sk))
                        sctp_icmp_frag_needed(sk, asoc, t, info);
                return;
        case ICMPV6_PARAMPROB:
                if (ICMPV6_UNK_NEXTHDR == code) {
                        sctp_icmp_proto_unreachable(sk, asoc, t);
                        return;
                }
                break;
        case NDISC_REDIRECT:
                sctp_icmp_redirect(sk, t, skb);
                return;
        default:
                break;
        }

        icmpv6_err_convert(type, code, &err);
        if (!sock_owned_by_user(sk) && inet6_test_bit(RECVERR6, sk)) {
                sk->sk_err = err;
                sk_error_report(sk);
        } else {
                WRITE_ONCE(sk->sk_err_soft, err);
        }
}

/* ICMP error handler. */
static int sctp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
                       u8 type, u8 code, int offset, __be32 info)
{
        struct net *net = dev_net(skb->dev);
        struct sctp_transport *transport;
        struct sctp_association *asoc;
        __u16 saveip, savesctp;
        struct sock *sk;

        /* Fix up skb to look at the embedded net header. */
        saveip   = skb->network_header;
        savesctp = skb->transport_header;
        skb_reset_network_header(skb);
        skb_set_transport_header(skb, offset);
        sk = sctp_err_lookup(net, AF_INET6, skb, sctp_hdr(skb), &asoc, &transport);
        /* Put back, the original pointers. */
        skb->network_header   = saveip;
        skb->transport_header = savesctp;
        if (!sk) {
                __ICMP6_INC_STATS(net, __in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);
                return -ENOENT;
        }

        sctp_v6_err_handle(transport, skb, type, code, ntohl(info));
        sctp_err_finish(sk, transport);

        return 0;
}

int sctp_udp_v6_err(struct sock *sk, struct sk_buff *skb)
{
        struct net *net = dev_net(skb->dev);
        struct sctp_association *asoc;
        struct sctp_transport *t;
        struct icmp6hdr *hdr;
        __u32 info = 0;

        skb->transport_header += sizeof(struct udphdr);
        sk = sctp_err_lookup(net, AF_INET6, skb, sctp_hdr(skb), &asoc, &t);
        if (!sk) {
                __ICMP6_INC_STATS(net, __in6_dev_get(skb->dev), ICMP6_MIB_INERRORS);
                return -ENOENT;
        }

        skb->transport_header -= sizeof(struct udphdr);
        hdr = (struct icmp6hdr *)(skb_network_header(skb) - sizeof(struct icmp6hdr));
        if (hdr->icmp6_type == NDISC_REDIRECT) {
                /* can't be handled without outer ip6hdr known, leave it to udpv6_err */
                sctp_err_finish(sk, t);
                return 0;
        }
        if (hdr->icmp6_type == ICMPV6_PKT_TOOBIG)
                info = ntohl(hdr->icmp6_mtu);
        sctp_v6_err_handle(t, skb, hdr->icmp6_type, hdr->icmp6_code, info);

        sctp_err_finish(sk, t);
        return 1;
}

static int sctp_v6_xmit(struct sk_buff *skb, struct sctp_transport *t)
{
        struct dst_entry *dst = dst_clone(t->dst);
        struct flowi6 *fl6 = &t->fl.u.ip6;
        struct sock *sk = skb->sk;
        struct ipv6_pinfo *np = inet6_sk(sk);
        __u8 tclass = np->tclass;
        __be32 label;

        pr_debug("%s: skb:%p, len:%d, src:%pI6 dst:%pI6\n", __func__, skb,
                 skb->len, &fl6->saddr, &fl6->daddr);

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

        if (INET_ECN_is_capable(tclass))
                IP6_ECN_flow_xmit(sk, fl6->flowlabel);

        if (!(t->param_flags & SPP_PMTUD_ENABLE))
                skb->ignore_df = 1;

        SCTP_INC_STATS(sock_net(sk), SCTP_MIB_OUTSCTPPACKS);

        if (!t->encap_port || !sctp_sk(sk)->udp_port) {
                int res;

                skb_dst_set(skb, dst);
                rcu_read_lock();
                res = ip6_xmit(sk, skb, fl6, sk->sk_mark,
                               rcu_dereference(np->opt),
                               tclass, READ_ONCE(sk->sk_priority));
                rcu_read_unlock();
                return res;
        }

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

        skb->encapsulation = 1;
        skb_reset_inner_mac_header(skb);
        skb_reset_inner_transport_header(skb);
        skb_set_inner_ipproto(skb, IPPROTO_SCTP);
        label = ip6_make_flowlabel(sock_net(sk), skb, fl6->flowlabel, true, fl6);

        udp_tunnel6_xmit_skb(dst, sk, skb, NULL, &fl6->saddr, &fl6->daddr,
                             tclass, ip6_dst_hoplimit(dst), label,
                             sctp_sk(sk)->udp_port, t->encap_port, false, 0);
        return 0;
}

/* Returns the dst cache entry for the given source and destination ip
 * addresses.
 */
static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
                            struct flowi *fl, struct sock *sk)
{
        struct sctp_association *asoc = t->asoc;
        struct dst_entry *dst = NULL;
        struct flowi _fl;
        struct flowi6 *fl6 = &_fl.u.ip6;
        struct sctp_bind_addr *bp;
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct sctp_sockaddr_entry *laddr;
        union sctp_addr *daddr = &t->ipaddr;
        union sctp_addr dst_saddr;
        struct in6_addr *final_p, final;
        enum sctp_scope scope;
        __u8 matchlen = 0;

        memset(&_fl, 0, sizeof(_fl));
        fl6->daddr = daddr->v6.sin6_addr;
        fl6->fl6_dport = daddr->v6.sin6_port;
        fl6->flowi6_proto = IPPROTO_SCTP;
        if (ipv6_addr_type(&daddr->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL)
                fl6->flowi6_oif = daddr->v6.sin6_scope_id;
        else if (asoc)
                fl6->flowi6_oif = asoc->base.sk->sk_bound_dev_if;
        if (t->flowlabel & SCTP_FLOWLABEL_SET_MASK)
                fl6->flowlabel = htonl(t->flowlabel & SCTP_FLOWLABEL_VAL_MASK);

        if (inet6_test_bit(SNDFLOW, sk) &&
            (fl6->flowlabel & IPV6_FLOWLABEL_MASK)) {
                struct ip6_flowlabel *flowlabel;

                flowlabel = fl6_sock_lookup(sk, fl6->flowlabel);
                if (IS_ERR(flowlabel))
                        goto out;
                fl6_sock_release(flowlabel);
        }

        pr_debug("%s: dst=%pI6 ", __func__, &fl6->daddr);

        if (asoc)
                fl6->fl6_sport = htons(asoc->base.bind_addr.port);

        if (saddr) {
                fl6->saddr = saddr->v6.sin6_addr;
                if (!fl6->fl6_sport)
                        fl6->fl6_sport = saddr->v6.sin6_port;

                pr_debug("src=%pI6 - ", &fl6->saddr);
        }

        rcu_read_lock();
        final_p = fl6_update_dst(fl6, rcu_dereference(np->opt), &final);
        rcu_read_unlock();

        dst = ip6_dst_lookup_flow(sock_net(sk), sk, fl6, final_p);
        if (!asoc || saddr) {
                t->dst = dst;
                memcpy(fl, &_fl, sizeof(_fl));
                goto out;
        }

        bp = &asoc->base.bind_addr;
        scope = sctp_scope(daddr);
        /* ip6_dst_lookup has filled in the fl6->saddr for us.  Check
         * to see if we can use it.
         */
        if (!IS_ERR(dst)) {
                /* Walk through the bind address list and look for a bind
                 * address that matches the source address of the returned dst.
                 */
                sctp_v6_to_addr(&dst_saddr, &fl6->saddr, 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;

                        /* Do not compare against v4 addrs */
                        if ((laddr->a.sa.sa_family == AF_INET6) &&
                            (sctp_v6_cmp_addr(&dst_saddr, &laddr->a))) {
                                rcu_read_unlock();
                                t->dst = dst;
                                memcpy(fl, &_fl, sizeof(_fl));
                                goto out;
                        }
                }
                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 the
         * best source address for a given destination.
         */
        rcu_read_lock();
        list_for_each_entry_rcu(laddr, &bp->address_list, list) {
                struct dst_entry *bdst;
                __u8 bmatchlen;

                if (!laddr->valid ||
                    laddr->state != SCTP_ADDR_SRC ||
                    laddr->a.sa.sa_family != AF_INET6 ||
                    scope > sctp_scope(&laddr->a))
                        continue;

                fl6->saddr = laddr->a.v6.sin6_addr;
                fl6->fl6_sport = laddr->a.v6.sin6_port;
                final_p = fl6_update_dst(fl6, rcu_dereference(np->opt), &final);
                bdst = ip6_dst_lookup_flow(sock_net(sk), sk, fl6, final_p);

                if (IS_ERR(bdst))
                        continue;

                if (ipv6_chk_addr(dev_net(bdst->dev),
                                  &laddr->a.v6.sin6_addr, bdst->dev, 1)) {
                        if (!IS_ERR_OR_NULL(dst))
                                dst_release(dst);
                        dst = bdst;
                        t->dst = dst;
                        memcpy(fl, &_fl, sizeof(_fl));
                        break;
                }

                bmatchlen = sctp_v6_addr_match_len(daddr, &laddr->a);
                if (matchlen > bmatchlen) {
                        dst_release(bdst);
                        continue;
                }

                if (!IS_ERR_OR_NULL(dst))
                        dst_release(dst);
                dst = bdst;
                matchlen = bmatchlen;
                t->dst = dst;
                memcpy(fl, &_fl, sizeof(_fl));
        }
        rcu_read_unlock();

out:
        if (!IS_ERR_OR_NULL(dst)) {
                struct rt6_info *rt;

                rt = dst_rt6_info(dst);
                t->dst_cookie = rt6_get_cookie(rt);
                pr_debug("rt6_dst:%pI6/%d rt6_src:%pI6\n",
                         &rt->rt6i_dst.addr, rt->rt6i_dst.plen,
                         &fl->u.ip6.saddr);
        } else {
                t->dst = NULL;
                pr_debug("no route\n");
        }
}

/* Returns the number of consecutive initial bits that match in the 2 ipv6
 * addresses.
 */
static inline int sctp_v6_addr_match_len(union sctp_addr *s1,
                                         union sctp_addr *s2)
{
        return ipv6_addr_diff(&s1->v6.sin6_addr, &s2->v6.sin6_addr);
}

/* Fills in the source address(saddr) based on the destination address(daddr)
 * and asoc's bind address list.
 */
static void sctp_v6_get_saddr(struct sctp_sock *sk,
                              struct sctp_transport *t,
                              struct flowi *fl)
{
        struct flowi6 *fl6 = &fl->u.ip6;
        union sctp_addr *saddr = &t->saddr;

        pr_debug("%s: asoc:%p dst:%p\n", __func__, t->asoc, t->dst);

        if (t->dst) {
                saddr->v6.sin6_family = AF_INET6;
                saddr->v6.sin6_addr = fl6->saddr;
        }
}

/* Make a copy of all potential local addresses. */
static void sctp_v6_copy_addrlist(struct list_head *addrlist,
                                  struct net_device *dev)
{
        struct inet6_dev *in6_dev;
        struct inet6_ifaddr *ifp;
        struct sctp_sockaddr_entry *addr;

        rcu_read_lock();
        if ((in6_dev = __in6_dev_get(dev)) == NULL) {
                rcu_read_unlock();
                return;
        }

        read_lock_bh(&in6_dev->lock);
        list_for_each_entry(ifp, &in6_dev->addr_list, if_list) {
                /* Add the address to the local list.  */
                addr = kzalloc_obj(*addr, GFP_ATOMIC);
                if (addr) {
                        addr->a.v6.sin6_family = AF_INET6;
                        addr->a.v6.sin6_addr = ifp->addr;
                        addr->a.v6.sin6_scope_id = dev->ifindex;
                        addr->valid = 1;
                        INIT_LIST_HEAD(&addr->list);
                        list_add_tail(&addr->list, addrlist);
                }
        }

        read_unlock_bh(&in6_dev->lock);
        rcu_read_unlock();
}

/* Copy over any ip options */
static void sctp_v6_copy_ip_options(struct sock *sk, struct sock *newsk)
{
        struct ipv6_pinfo *newnp, *np = inet6_sk(sk);
        struct ipv6_txoptions *opt;

        inet_sk(newsk)->inet_opt = NULL;

        newnp = inet6_sk(newsk);

        rcu_read_lock();
        opt = rcu_dereference(np->opt);
        if (opt) {
                opt = ipv6_dup_options(newsk, opt);
                if (!opt)
                        pr_err("%s: Failed to copy ip options\n", __func__);
        }
        RCU_INIT_POINTER(newnp->opt, opt);
        rcu_read_unlock();
}

/* Account for the IP options */
static int sctp_v6_ip_options_len(struct sock *sk)
{
        struct ipv6_pinfo *np = inet6_sk(sk);
        struct ipv6_txoptions *opt;
        int len = 0;

        rcu_read_lock();
        opt = rcu_dereference(np->opt);
        if (opt)
                len = opt->opt_flen + opt->opt_nflen;

        rcu_read_unlock();
        return len;
}

/* Initialize a sockaddr_storage from in incoming skb. */
static void sctp_v6_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_in6 *sa = &addr->v6;

        addr->v6.sin6_family = AF_INET6;
        addr->v6.sin6_flowinfo = 0; /* FIXME */
        addr->v6.sin6_scope_id = ((struct inet6_skb_parm *)skb->cb)->iif;

        if (is_saddr) {
                sa->sin6_port = sh->source;
                sa->sin6_addr = ipv6_hdr(skb)->saddr;
        } else {
                sa->sin6_port = sh->dest;
                sa->sin6_addr = ipv6_hdr(skb)->daddr;
        }
}

/* Initialize an sctp_addr from a socket. */
static void sctp_v6_from_sk(union sctp_addr *addr, struct sock *sk)
{
        addr->v6.sin6_family = AF_INET6;
        addr->v6.sin6_port = 0;
        addr->v6.sin6_flowinfo = 0;
        addr->v6.sin6_addr = sk->sk_v6_rcv_saddr;
        addr->v6.sin6_scope_id = 0;
}

/* Initialize sk->sk_rcv_saddr from sctp_addr. */
static void sctp_v6_to_sk_saddr(union sctp_addr *addr, struct sock *sk)
{
        if (addr->sa.sa_family == AF_INET) {
                sk->sk_v6_rcv_saddr.s6_addr32[0] = 0;
                sk->sk_v6_rcv_saddr.s6_addr32[1] = 0;
                sk->sk_v6_rcv_saddr.s6_addr32[2] = htonl(0x0000ffff);
                sk->sk_v6_rcv_saddr.s6_addr32[3] =
                        addr->v4.sin_addr.s_addr;
        } else {
                sk->sk_v6_rcv_saddr = addr->v6.sin6_addr;
        }
}

/* Initialize sk->sk_daddr from sctp_addr. */
static void sctp_v6_to_sk_daddr(union sctp_addr *addr, struct sock *sk)
{
        if (addr->sa.sa_family == AF_INET) {
                sk->sk_v6_daddr.s6_addr32[0] = 0;
                sk->sk_v6_daddr.s6_addr32[1] = 0;
                sk->sk_v6_daddr.s6_addr32[2] = htonl(0x0000ffff);
                sk->sk_v6_daddr.s6_addr32[3] = addr->v4.sin_addr.s_addr;
        } else {
                sk->sk_v6_daddr = addr->v6.sin6_addr;
        }
}

/* Initialize a sctp_addr from an address parameter. */
static bool sctp_v6_from_addr_param(union sctp_addr *addr,
                                    union sctp_addr_param *param,
                                    __be16 port, int iif)
{
        if (ntohs(param->v6.param_hdr.length) < sizeof(struct sctp_ipv6addr_param))
                return false;

        addr->v6.sin6_family = AF_INET6;
        addr->v6.sin6_port = port;
        addr->v6.sin6_flowinfo = 0; /* BUG */
        addr->v6.sin6_addr = param->v6.addr;
        addr->v6.sin6_scope_id = iif;

        return true;
}

/* Initialize an address parameter from a sctp_addr and return the length
 * of the address parameter.
 */
static int sctp_v6_to_addr_param(const union sctp_addr *addr,
                                 union sctp_addr_param *param)
{
        int length = sizeof(struct sctp_ipv6addr_param);

        param->v6.param_hdr.type = SCTP_PARAM_IPV6_ADDRESS;
        param->v6.param_hdr.length = htons(length);
        param->v6.addr = addr->v6.sin6_addr;

        return length;
}

/* Initialize a sctp_addr from struct in6_addr. */
static void sctp_v6_to_addr(union sctp_addr *addr, struct in6_addr *saddr,
                              __be16 port)
{
        addr->sa.sa_family = AF_INET6;
        addr->v6.sin6_port = port;
        addr->v6.sin6_flowinfo = 0;
        addr->v6.sin6_addr = *saddr;
        addr->v6.sin6_scope_id = 0;
}

static int __sctp_v6_cmp_addr(const union sctp_addr *addr1,
                              const union sctp_addr *addr2)
{
        if (addr1->sa.sa_family != addr2->sa.sa_family) {
                if (addr1->sa.sa_family == AF_INET &&
                    addr2->sa.sa_family == AF_INET6 &&
                    ipv6_addr_v4mapped(&addr2->v6.sin6_addr) &&
                    addr2->v6.sin6_addr.s6_addr32[3] ==
                    addr1->v4.sin_addr.s_addr)
                        return 1;

                if (addr2->sa.sa_family == AF_INET &&
                    addr1->sa.sa_family == AF_INET6 &&
                    ipv6_addr_v4mapped(&addr1->v6.sin6_addr) &&
                    addr1->v6.sin6_addr.s6_addr32[3] ==
                    addr2->v4.sin_addr.s_addr)
                        return 1;

                return 0;
        }

        if (!ipv6_addr_equal(&addr1->v6.sin6_addr, &addr2->v6.sin6_addr))
                return 0;

        /* If this is a linklocal address, compare the scope_id. */
        if ((ipv6_addr_type(&addr1->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL) &&
            addr1->v6.sin6_scope_id && addr2->v6.sin6_scope_id &&
            addr1->v6.sin6_scope_id != addr2->v6.sin6_scope_id)
                return 0;

        return 1;
}

/* Compare addresses exactly.
 * v4-mapped-v6 is also in consideration.
 */
static int sctp_v6_cmp_addr(const union sctp_addr *addr1,
                            const union sctp_addr *addr2)
{
        return __sctp_v6_cmp_addr(addr1, addr2) &&
               addr1->v6.sin6_port == addr2->v6.sin6_port;
}

/* Initialize addr struct to INADDR_ANY. */
static void sctp_v6_inaddr_any(union sctp_addr *addr, __be16 port)
{
        memset(addr, 0x00, sizeof(union sctp_addr));
        addr->v6.sin6_family = AF_INET6;
        addr->v6.sin6_port = port;
}

/* Is this a wildcard address? */
static int sctp_v6_is_any(const union sctp_addr *addr)
{
        return ipv6_addr_any(&addr->v6.sin6_addr);
}

/* Should this be available for binding?   */
static int sctp_v6_available(union sctp_addr *addr, struct sctp_sock *sp)
{
        const struct in6_addr *in6 = (const struct in6_addr *)&addr->v6.sin6_addr;
        struct sock *sk = &sp->inet.sk;
        struct net *net = sock_net(sk);
        struct net_device *dev = NULL;
        int type, res, bound_dev_if;

        type = ipv6_addr_type(in6);
        if (IPV6_ADDR_ANY == type)
                return 1;
        if (type == IPV6_ADDR_MAPPED) {
                if (sp && ipv6_only_sock(sctp_opt2sk(sp)))
                        return 0;
                sctp_v6_map_v4(addr);
                return sctp_get_af_specific(AF_INET)->available(addr, sp);
        }
        if (!(type & IPV6_ADDR_UNICAST))
                return 0;

        rcu_read_lock();
        bound_dev_if = READ_ONCE(sk->sk_bound_dev_if);
        if (bound_dev_if) {
                res = 0;
                dev = dev_get_by_index_rcu(net, bound_dev_if);
                if (!dev)
                        goto out;
        }

        res = ipv6_can_nonlocal_bind(net, &sp->inet) ||
              ipv6_chk_addr(net, in6, dev, 0);

out:
        rcu_read_unlock();
        return res;
}

/* This function checks if the address is a valid address to be used for
 * SCTP.
 *
 * 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_v6_addr_valid(union sctp_addr *addr,
                              struct sctp_sock *sp,
                              const struct sk_buff *skb)
{
        int ret = ipv6_addr_type(&addr->v6.sin6_addr);

        /* Support v4-mapped-v6 address. */
        if (ret == IPV6_ADDR_MAPPED) {
                /* Note: This routine is used in input, so v4-mapped-v6
                 * are disallowed here when there is no sctp_sock.
                 */
                if (sp && ipv6_only_sock(sctp_opt2sk(sp)))
                        return 0;
                sctp_v6_map_v4(addr);
                return sctp_get_af_specific(AF_INET)->addr_valid(addr, sp, skb);
        }

        /* Is this a non-unicast address */
        if (!(ret & IPV6_ADDR_UNICAST))
                return 0;

        return 1;
}

/* What is the scope of 'addr'?  */
static enum sctp_scope sctp_v6_scope(union sctp_addr *addr)
{
        enum sctp_scope retval;
        int v6scope;

        /* The IPv6 scope is really a set of bit fields.
         * See IFA_* in <net/if_inet6.h>.  Map to a generic SCTP scope.
         */

        v6scope = ipv6_addr_scope(&addr->v6.sin6_addr);
        switch (v6scope) {
        case IFA_HOST:
                retval = SCTP_SCOPE_LOOPBACK;
                break;
        case IFA_LINK:
                retval = SCTP_SCOPE_LINK;
                break;
        case IFA_SITE:
                retval = SCTP_SCOPE_PRIVATE;
                break;
        default:
                retval = SCTP_SCOPE_GLOBAL;
                break;
        }

        return retval;
}

/* Format a sockaddr for return to user space. This makes sure the return is
 * AF_INET or AF_INET6 depending on the SCTP_I_WANT_MAPPED_V4_ADDR option.
 */
static int sctp_v6_addr_to_user(struct sctp_sock *sp, union sctp_addr *addr)
{
        if (sp->v4mapped) {
                if (addr->sa.sa_family == AF_INET)
                        sctp_v4_map_v6(addr);
        } else {
                if (addr->sa.sa_family == AF_INET6 &&
                    ipv6_addr_v4mapped(&addr->v6.sin6_addr))
                        sctp_v6_map_v4(addr);
        }

        if (addr->sa.sa_family == AF_INET) {
                memset(addr->v4.sin_zero, 0, sizeof(addr->v4.sin_zero));
                return sizeof(struct sockaddr_in);
        }
        return sizeof(struct sockaddr_in6);
}

/* Where did this skb come from?  */
static int sctp_v6_skb_iif(const struct sk_buff *skb)
{
        return inet6_iif(skb);
}

static int sctp_v6_skb_sdif(const struct sk_buff *skb)
{
        return inet6_sdif(skb);
}

/* Was this packet marked by Explicit Congestion Notification? */
static int sctp_v6_is_ce(const struct sk_buff *skb)
{
        return *((__u32 *)(ipv6_hdr(skb))) & (__force __u32)htonl(1 << 20);
}

/* Dump the v6 addr to the seq file. */
static void sctp_v6_seq_dump_addr(struct seq_file *seq, union sctp_addr *addr)
{
        seq_printf(seq, "%pI6 ", &addr->v6.sin6_addr);
}

static void sctp_v6_ecn_capable(struct sock *sk)
{
        inet6_sk(sk)->tclass |= INET_ECN_ECT_0;
}

/* Initialize a PF_INET msgname from a ulpevent. */
static void sctp_inet6_event_msgname(struct sctp_ulpevent *event,
                                     char *msgname, int *addrlen)
{
        union sctp_addr *addr;
        struct sctp_association *asoc;
        union sctp_addr *paddr;

        if (!msgname)
                return;

        addr = (union sctp_addr *)msgname;
        asoc = event->asoc;
        paddr = &asoc->peer.primary_addr;

        if (paddr->sa.sa_family == AF_INET) {
                addr->v4.sin_family = AF_INET;
                addr->v4.sin_port = htons(asoc->peer.port);
                addr->v4.sin_addr = paddr->v4.sin_addr;
        } else {
                addr->v6.sin6_family = AF_INET6;
                addr->v6.sin6_flowinfo = 0;
                if (ipv6_addr_type(&paddr->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL)
                        addr->v6.sin6_scope_id = paddr->v6.sin6_scope_id;
                else
                        addr->v6.sin6_scope_id = 0;
                addr->v6.sin6_port = htons(asoc->peer.port);
                addr->v6.sin6_addr = paddr->v6.sin6_addr;
        }

        *addrlen = sctp_v6_addr_to_user(sctp_sk(asoc->base.sk), addr);
}

/* Initialize a msg_name from an inbound skb. */
static void sctp_inet6_skb_msgname(struct sk_buff *skb, char *msgname,
                                   int *addr_len)
{
        union sctp_addr *addr;
        struct sctphdr *sh;

        if (!msgname)
                return;

        addr = (union sctp_addr *)msgname;
        sh = sctp_hdr(skb);

        if (ip_hdr(skb)->version == 4) {
                addr->v4.sin_family = AF_INET;
                addr->v4.sin_port = sh->source;
                addr->v4.sin_addr.s_addr = ip_hdr(skb)->saddr;
        } else {
                addr->v6.sin6_family = AF_INET6;
                addr->v6.sin6_flowinfo = 0;
                addr->v6.sin6_port = sh->source;
                addr->v6.sin6_addr = ipv6_hdr(skb)->saddr;
                if (ipv6_addr_type(&addr->v6.sin6_addr) & IPV6_ADDR_LINKLOCAL)
                        addr->v6.sin6_scope_id = sctp_v6_skb_iif(skb);
                else
                        addr->v6.sin6_scope_id = 0;
        }

        *addr_len = sctp_v6_addr_to_user(sctp_sk(skb->sk), addr);
}

/* Do we support this AF? */
static int sctp_inet6_af_supported(sa_family_t family, struct sctp_sock *sp)
{
        switch (family) {
        case AF_INET6:
                return 1;
        /* v4-mapped-v6 addresses */
        case AF_INET:
                if (!ipv6_only_sock(sctp_opt2sk(sp)))
                        return 1;
                fallthrough;
        default:
                return 0;
        }
}

/* Address matching with wildcards allowed.  This extra level
 * of indirection lets us choose whether a PF_INET6 should
 * disallow any v4 addresses if we so choose.
 */
static int sctp_inet6_cmp_addr(const union sctp_addr *addr1,
                               const union sctp_addr *addr2,
                               struct sctp_sock *opt)
{
        struct sock *sk = sctp_opt2sk(opt);
        struct sctp_af *af1, *af2;

        af1 = sctp_get_af_specific(addr1->sa.sa_family);
        af2 = sctp_get_af_specific(addr2->sa.sa_family);

        if (!af1 || !af2)
                return 0;

        /* If the socket is IPv6 only, v4 addrs will not match */
        if (ipv6_only_sock(sk) && af1 != af2)
                return 0;

        /* Today, wildcard AF_INET/AF_INET6. */
        if (sctp_is_any(sk, addr1) || sctp_is_any(sk, addr2))
                return 1;

        if (addr1->sa.sa_family == AF_INET && addr2->sa.sa_family == AF_INET)
                return addr1->v4.sin_addr.s_addr == addr2->v4.sin_addr.s_addr;

        return __sctp_v6_cmp_addr(addr1, addr2);
}

/* Verify that the provided sockaddr looks bindable.   Common verification,
 * has already been taken care of.
 */
static int sctp_inet6_bind_verify(struct sctp_sock *opt, union sctp_addr *addr)
{
        struct sctp_af *af;

        /* ASSERT: address family has already been verified. */
        if (addr->sa.sa_family != AF_INET6)
                af = sctp_get_af_specific(addr->sa.sa_family);
        else {
                int type = ipv6_addr_type(&addr->v6.sin6_addr);
                struct net_device *dev;

                if (type & IPV6_ADDR_LINKLOCAL) {
                        struct net *net;
                        if (!addr->v6.sin6_scope_id)
                                return 0;
                        net = sock_net(&opt->inet.sk);
                        rcu_read_lock();
                        dev = dev_get_by_index_rcu(net, addr->v6.sin6_scope_id);
                        if (!dev || !(ipv6_can_nonlocal_bind(net, &opt->inet) ||
                                      ipv6_chk_addr(net, &addr->v6.sin6_addr,
                                                    dev, 0))) {
                                rcu_read_unlock();
                                return 0;
                        }
                        rcu_read_unlock();
                }

                af = opt->pf->af;
        }
        return af->available(addr, opt);
}

/* Verify that the provided sockaddr looks sendable.   Common verification,
 * has already been taken care of.
 */
static int sctp_inet6_send_verify(struct sctp_sock *opt, union sctp_addr *addr)
{
        struct sctp_af *af = NULL;

        /* ASSERT: address family has already been verified. */
        if (addr->sa.sa_family != AF_INET6)
                af = sctp_get_af_specific(addr->sa.sa_family);
        else {
                int type = ipv6_addr_type(&addr->v6.sin6_addr);
                struct net_device *dev;

                if (type & IPV6_ADDR_LINKLOCAL) {
                        if (!addr->v6.sin6_scope_id)
                                return 0;
                        rcu_read_lock();
                        dev = dev_get_by_index_rcu(sock_net(&opt->inet.sk),
                                                   addr->v6.sin6_scope_id);
                        rcu_read_unlock();
                        if (!dev)
                                return 0;
                }
                af = opt->pf->af;
        }

        return af != NULL;
}

/* Fill in Supported Address Type information for INIT and INIT-ACK
 * chunks.   Note: In the future, we may want to look at sock options
 * to determine whether a PF_INET6 socket really wants to have IPV4
 * addresses.
 * Returns number of addresses supported.
 */
static int sctp_inet6_supported_addrs(const struct sctp_sock *opt,
                                      __be16 *types)
{
        types[0] = SCTP_PARAM_IPV6_ADDRESS;
        if (!opt || !ipv6_only_sock(sctp_opt2sk(opt))) {
                types[1] = SCTP_PARAM_IPV4_ADDRESS;
                return 2;
        }
        return 1;
}

/* Handle SCTP_I_WANT_MAPPED_V4_ADDR for getpeername() and getsockname() */
static int sctp_getname(struct socket *sock, struct sockaddr *uaddr,
                        int peer)
{
        int rc;

        rc = inet6_getname(sock, uaddr, peer);

        if (rc < 0)
                return rc;

        rc = sctp_v6_addr_to_user(sctp_sk(sock->sk),
                                          (union sctp_addr *)uaddr);

        return rc;
}

static const struct proto_ops inet6_seqpacket_ops = {
        .family            = PF_INET6,
        .owner             = THIS_MODULE,
        .release           = inet6_release,
        .bind              = inet6_bind,
        .connect           = sctp_inet_connect,
        .socketpair        = sock_no_socketpair,
        .accept            = inet_accept,
        .getname           = sctp_getname,
        .poll              = sctp_poll,
        .ioctl             = inet6_ioctl,
        .gettstamp         = sock_gettstamp,
        .listen            = sctp_inet_listen,
        .shutdown          = inet_shutdown,
        .setsockopt        = sock_common_setsockopt,
        .getsockopt        = sock_common_getsockopt,
        .sendmsg           = inet_sendmsg,
        .recvmsg           = inet_recvmsg,
        .mmap              = sock_no_mmap,
#ifdef CONFIG_COMPAT
        .compat_ioctl      = inet6_compat_ioctl,
#endif
};

static struct inet_protosw sctpv6_seqpacket_protosw = {
        .type          = SOCK_SEQPACKET,
        .protocol      = IPPROTO_SCTP,
        .prot          = &sctpv6_prot,
        .ops           = &inet6_seqpacket_ops,
        .flags         = SCTP_PROTOSW_FLAG
};
static struct inet_protosw sctpv6_stream_protosw = {
        .type          = SOCK_STREAM,
        .protocol      = IPPROTO_SCTP,
        .prot          = &sctpv6_prot,
        .ops           = &inet6_seqpacket_ops,
        .flags         = SCTP_PROTOSW_FLAG,
};

static int sctp6_rcv(struct sk_buff *skb)
{
        SCTP_INPUT_CB(skb)->encap_port = 0;
        return sctp_rcv(skb) ? -1 : 0;
}

static const struct inet6_protocol sctpv6_protocol = {
        .handler      = sctp6_rcv,
        .err_handler  = sctp_v6_err,
        .flags        = INET6_PROTO_NOPOLICY | INET6_PROTO_FINAL,
};

static struct sctp_af sctp_af_inet6 = {
        .sa_family         = AF_INET6,
        .sctp_xmit         = sctp_v6_xmit,
        .setsockopt        = ipv6_setsockopt,
        .getsockopt        = ipv6_getsockopt,
        .get_dst           = sctp_v6_get_dst,
        .get_saddr         = sctp_v6_get_saddr,
        .copy_addrlist     = sctp_v6_copy_addrlist,
        .from_skb          = sctp_v6_from_skb,
        .from_sk           = sctp_v6_from_sk,
        .from_addr_param   = sctp_v6_from_addr_param,
        .to_addr_param     = sctp_v6_to_addr_param,
        .cmp_addr          = sctp_v6_cmp_addr,
        .scope             = sctp_v6_scope,
        .addr_valid        = sctp_v6_addr_valid,
        .inaddr_any        = sctp_v6_inaddr_any,
        .is_any            = sctp_v6_is_any,
        .available         = sctp_v6_available,
        .skb_iif           = sctp_v6_skb_iif,
        .skb_sdif          = sctp_v6_skb_sdif,
        .is_ce             = sctp_v6_is_ce,
        .seq_dump_addr     = sctp_v6_seq_dump_addr,
        .ecn_capable       = sctp_v6_ecn_capable,
        .net_header_len    = sizeof(struct ipv6hdr),
        .sockaddr_len      = sizeof(struct sockaddr_in6),
        .ip_options_len    = sctp_v6_ip_options_len,
};

static struct sctp_pf sctp_pf_inet6 = {
        .event_msgname = sctp_inet6_event_msgname,
        .skb_msgname   = sctp_inet6_skb_msgname,
        .af_supported  = sctp_inet6_af_supported,
        .cmp_addr      = sctp_inet6_cmp_addr,
        .bind_verify   = sctp_inet6_bind_verify,
        .send_verify   = sctp_inet6_send_verify,
        .supported_addrs = sctp_inet6_supported_addrs,
        .addr_to_user  = sctp_v6_addr_to_user,
        .to_sk_saddr   = sctp_v6_to_sk_saddr,
        .to_sk_daddr   = sctp_v6_to_sk_daddr,
        .copy_ip_options = sctp_v6_copy_ip_options,
        .af            = &sctp_af_inet6,
};

/* Initialize IPv6 support and register with socket layer.  */
void sctp_v6_pf_init(void)
{
        /* Register the SCTP specific PF_INET6 functions. */
        sctp_register_pf(&sctp_pf_inet6, PF_INET6);

        /* Register the SCTP specific AF_INET6 functions. */
        sctp_register_af(&sctp_af_inet6);
}

void sctp_v6_pf_exit(void)
{
        list_del(&sctp_af_inet6.list);
}

/* Initialize IPv6 support and register with socket layer.  */
int sctp_v6_protosw_init(void)
{
        int rc;

        rc = proto_register(&sctpv6_prot, 1);
        if (rc)
                return rc;

        /* Add SCTPv6(UDP and TCP style) to inetsw6 linked list. */
        inet6_register_protosw(&sctpv6_seqpacket_protosw);
        inet6_register_protosw(&sctpv6_stream_protosw);

        return 0;
}

void sctp_v6_protosw_exit(void)
{
        inet6_unregister_protosw(&sctpv6_seqpacket_protosw);
        inet6_unregister_protosw(&sctpv6_stream_protosw);
        proto_unregister(&sctpv6_prot);
}


/* Register with inet6 layer. */
int sctp_v6_add_protocol(void)
{
        /* Register notifier for inet6 address additions/deletions. */
        register_inet6addr_notifier(&sctp_inet6addr_notifier);

        if (inet6_add_protocol(&sctpv6_protocol, IPPROTO_SCTP) < 0)
                return -EAGAIN;

        return 0;
}

/* Unregister with inet6 layer. */
void sctp_v6_del_protocol(void)
{
        inet6_del_protocol(&sctpv6_protocol, IPPROTO_SCTP);
        unregister_inet6addr_notifier(&sctp_inet6addr_notifier);
}