// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * INET         An implementation of the TCP/IP protocol suite for the LINUX
 *              operating system.  INET is implemented using the BSD Socket
 *              interface as the means of communication with the user level.
 *
 *              Generic INET transport hashtables
 *
 * Authors:     Lotsa people, from code originally in tcp
 */

#include <linux/module.h>
#include <linux/random.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <linux/vmalloc.h>
#include <linux/memblock.h>

#include <net/addrconf.h>
#include <net/inet_connection_sock.h>
#include <net/inet_hashtables.h>
#if IS_ENABLED(CONFIG_IPV6)
#include <net/inet6_hashtables.h>
#endif
#include <net/hotdata.h>
#include <net/ip.h>
#include <net/rps.h>
#include <net/secure_seq.h>
#include <net/sock_reuseport.h>
#include <net/tcp.h>

u32 inet_ehashfn(const struct net *net, const __be32 laddr,
                 const __u16 lport, const __be32 faddr,
                 const __be16 fport)
{
        net_get_random_once(&inet_ehash_secret, sizeof(inet_ehash_secret));

        return lport + __inet_ehashfn(laddr, 0, faddr, fport,
                                      inet_ehash_secret + net_hash_mix(net));
}
EXPORT_SYMBOL_GPL(inet_ehashfn);

/* This function handles inet_sock, but also timewait and request sockets
 * for IPv4/IPv6.
 */
static u32 sk_ehashfn(const struct sock *sk)
{
#if IS_ENABLED(CONFIG_IPV6)
        if (sk->sk_family == AF_INET6 &&
            !ipv6_addr_v4mapped(&sk->sk_v6_daddr))
                return inet6_ehashfn(sock_net(sk),
                                     &sk->sk_v6_rcv_saddr, sk->sk_num,
                                     &sk->sk_v6_daddr, sk->sk_dport);
#endif
        return inet_ehashfn(sock_net(sk),
                            sk->sk_rcv_saddr, sk->sk_num,
                            sk->sk_daddr, sk->sk_dport);
}

static bool sk_is_connect_bind(const struct sock *sk)
{
        if (sk->sk_state == TCP_TIME_WAIT)
                return inet_twsk(sk)->tw_connect_bind;
        else
                return sk->sk_userlocks & SOCK_CONNECT_BIND;
}

/*
 * Allocate and initialize a new local port bind bucket.
 * The bindhash mutex for snum's hash chain must be held here.
 */
struct inet_bind_bucket *inet_bind_bucket_create(struct kmem_cache *cachep,
                                                 struct net *net,
                                                 struct inet_bind_hashbucket *head,
                                                 const unsigned short snum,
                                                 int l3mdev)
{
        struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);

        if (tb) {
                write_pnet(&tb->ib_net, net);
                tb->l3mdev    = l3mdev;
                tb->port      = snum;
                tb->fastreuse = 0;
                tb->fastreuseport = 0;
                INIT_HLIST_HEAD(&tb->bhash2);
                hlist_add_head_rcu(&tb->node, &head->chain);
        }
        return tb;
}

/*
 * Caller must hold hashbucket lock for this tb with local BH disabled
 */
void inet_bind_bucket_destroy(struct inet_bind_bucket *tb)
{
        const struct inet_bind2_bucket *tb2;

        if (hlist_empty(&tb->bhash2)) {
                hlist_del_rcu(&tb->node);
                kfree_rcu(tb, rcu);
                return;
        }

        if (tb->fastreuse == -1 && tb->fastreuseport == -1)
                return;
        hlist_for_each_entry(tb2, &tb->bhash2, bhash_node) {
                if (tb2->fastreuse != -1 || tb2->fastreuseport != -1)
                        return;
        }
        tb->fastreuse = -1;
        tb->fastreuseport = -1;
}

bool inet_bind_bucket_match(const struct inet_bind_bucket *tb, const struct net *net,
                            unsigned short port, int l3mdev)
{
        return net_eq(ib_net(tb), net) && tb->port == port &&
                tb->l3mdev == l3mdev;
}

static void inet_bind2_bucket_init(struct inet_bind2_bucket *tb2,
                                   struct net *net,
                                   struct inet_bind_hashbucket *head,
                                   struct inet_bind_bucket *tb,
                                   const struct sock *sk)
{
        write_pnet(&tb2->ib_net, net);
        tb2->l3mdev = tb->l3mdev;
        tb2->port = tb->port;
#if IS_ENABLED(CONFIG_IPV6)
        BUILD_BUG_ON(USHRT_MAX < (IPV6_ADDR_ANY | IPV6_ADDR_MAPPED));
        if (sk->sk_family == AF_INET6) {
                tb2->addr_type = ipv6_addr_type(&sk->sk_v6_rcv_saddr);
                tb2->v6_rcv_saddr = sk->sk_v6_rcv_saddr;
        } else {
                tb2->addr_type = IPV6_ADDR_MAPPED;
                ipv6_addr_set_v4mapped(sk->sk_rcv_saddr, &tb2->v6_rcv_saddr);
        }
#else
        tb2->rcv_saddr = sk->sk_rcv_saddr;
#endif
        tb2->fastreuse = 0;
        tb2->fastreuseport = 0;
        INIT_HLIST_HEAD(&tb2->owners);
        hlist_add_head(&tb2->node, &head->chain);
        hlist_add_head(&tb2->bhash_node, &tb->bhash2);
}

struct inet_bind2_bucket *inet_bind2_bucket_create(struct kmem_cache *cachep,
                                                   struct net *net,
                                                   struct inet_bind_hashbucket *head,
                                                   struct inet_bind_bucket *tb,
                                                   const struct sock *sk)
{
        struct inet_bind2_bucket *tb2 = kmem_cache_alloc(cachep, GFP_ATOMIC);

        if (tb2)
                inet_bind2_bucket_init(tb2, net, head, tb, sk);

        return tb2;
}

/* Caller must hold hashbucket lock for this tb with local BH disabled */
void inet_bind2_bucket_destroy(struct kmem_cache *cachep, struct inet_bind2_bucket *tb)
{
        const struct sock *sk;

        if (hlist_empty(&tb->owners)) {
                __hlist_del(&tb->node);
                __hlist_del(&tb->bhash_node);
                kmem_cache_free(cachep, tb);
                return;
        }

        if (tb->fastreuse == -1 && tb->fastreuseport == -1)
                return;
        sk_for_each_bound(sk, &tb->owners) {
                if (!sk_is_connect_bind(sk))
                        return;
        }
        tb->fastreuse = -1;
        tb->fastreuseport = -1;
}

static bool inet_bind2_bucket_addr_match(const struct inet_bind2_bucket *tb2,
                                         const struct sock *sk)
{
#if IS_ENABLED(CONFIG_IPV6)
        if (sk->sk_family == AF_INET6)
                return ipv6_addr_equal(&tb2->v6_rcv_saddr, &sk->sk_v6_rcv_saddr);

        if (tb2->addr_type != IPV6_ADDR_MAPPED)
                return false;
#endif
        return tb2->rcv_saddr == sk->sk_rcv_saddr;
}

void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
                    struct inet_bind2_bucket *tb2, unsigned short port)
{
        WRITE_ONCE(inet_sk(sk)->inet_num, port);
        inet_csk(sk)->icsk_bind_hash = tb;
        inet_csk(sk)->icsk_bind2_hash = tb2;
        sk_add_bind_node(sk, &tb2->owners);
}

/*
 * Get rid of any references to a local port held by the given sock.
 */
static void __inet_put_port(struct sock *sk)
{
        struct inet_hashinfo *hashinfo = tcp_get_hashinfo(sk);
        struct inet_bind_hashbucket *head, *head2;
        struct net *net = sock_net(sk);
        struct inet_bind_bucket *tb;
        int bhash;

        bhash = inet_bhashfn(net, inet_sk(sk)->inet_num, hashinfo->bhash_size);
        head = &hashinfo->bhash[bhash];
        head2 = inet_bhashfn_portaddr(hashinfo, sk, net, inet_sk(sk)->inet_num);

        spin_lock(&head->lock);
        tb = inet_csk(sk)->icsk_bind_hash;
        inet_csk(sk)->icsk_bind_hash = NULL;
        WRITE_ONCE(inet_sk(sk)->inet_num, 0);
        sk->sk_userlocks &= ~SOCK_CONNECT_BIND;

        spin_lock(&head2->lock);
        if (inet_csk(sk)->icsk_bind2_hash) {
                struct inet_bind2_bucket *tb2 = inet_csk(sk)->icsk_bind2_hash;

                __sk_del_bind_node(sk);
                inet_csk(sk)->icsk_bind2_hash = NULL;
                inet_bind2_bucket_destroy(hashinfo->bind2_bucket_cachep, tb2);
        }
        spin_unlock(&head2->lock);

        inet_bind_bucket_destroy(tb);
        spin_unlock(&head->lock);
}

void inet_put_port(struct sock *sk)
{
        local_bh_disable();
        __inet_put_port(sk);
        local_bh_enable();
}
EXPORT_SYMBOL(inet_put_port);

int __inet_inherit_port(const struct sock *sk, struct sock *child)
{
        struct inet_hashinfo *table = tcp_get_hashinfo(sk);
        unsigned short port = inet_sk(child)->inet_num;
        struct inet_bind_hashbucket *head, *head2;
        bool created_inet_bind_bucket = false;
        struct net *net = sock_net(sk);
        bool update_fastreuse = false;
        struct inet_bind2_bucket *tb2;
        struct inet_bind_bucket *tb;
        int bhash, l3mdev;

        bhash = inet_bhashfn(net, port, table->bhash_size);
        head = &table->bhash[bhash];
        head2 = inet_bhashfn_portaddr(table, child, net, port);

        spin_lock(&head->lock);
        spin_lock(&head2->lock);
        tb = inet_csk(sk)->icsk_bind_hash;
        tb2 = inet_csk(sk)->icsk_bind2_hash;
        if (unlikely(!tb || !tb2)) {
                spin_unlock(&head2->lock);
                spin_unlock(&head->lock);
                return -ENOENT;
        }
        if (tb->port != port) {
                l3mdev = inet_sk_bound_l3mdev(sk);

                /* NOTE: using tproxy and redirecting skbs to a proxy
                 * on a different listener port breaks the assumption
                 * that the listener socket's icsk_bind_hash is the same
                 * as that of the child socket. We have to look up or
                 * create a new bind bucket for the child here. */
                inet_bind_bucket_for_each(tb, &head->chain) {
                        if (inet_bind_bucket_match(tb, net, port, l3mdev))
                                break;
                }
                if (!tb) {
                        tb = inet_bind_bucket_create(table->bind_bucket_cachep,
                                                     net, head, port, l3mdev);
                        if (!tb) {
                                spin_unlock(&head2->lock);
                                spin_unlock(&head->lock);
                                return -ENOMEM;
                        }
                        created_inet_bind_bucket = true;
                }
                update_fastreuse = true;

                goto bhash2_find;
        } else if (!inet_bind2_bucket_addr_match(tb2, child)) {
                l3mdev = inet_sk_bound_l3mdev(sk);

bhash2_find:
                tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, child);
                if (!tb2) {
                        tb2 = inet_bind2_bucket_create(table->bind2_bucket_cachep,
                                                       net, head2, tb, child);
                        if (!tb2)
                                goto error;
                }
        }
        if (update_fastreuse)
                inet_csk_update_fastreuse(child, tb, tb2);
        inet_bind_hash(child, tb, tb2, port);
        spin_unlock(&head2->lock);
        spin_unlock(&head->lock);

        return 0;

error:
        if (created_inet_bind_bucket)
                inet_bind_bucket_destroy(tb);
        spin_unlock(&head2->lock);
        spin_unlock(&head->lock);
        return -ENOMEM;
}
EXPORT_SYMBOL_GPL(__inet_inherit_port);

static struct inet_listen_hashbucket *
inet_lhash2_bucket_sk(struct inet_hashinfo *h, struct sock *sk)
{
        u32 hash;

#if IS_ENABLED(CONFIG_IPV6)
        if (sk->sk_family == AF_INET6)
                hash = ipv6_portaddr_hash(sock_net(sk),
                                          &sk->sk_v6_rcv_saddr,
                                          inet_sk(sk)->inet_num);
        else
#endif
                hash = ipv4_portaddr_hash(sock_net(sk),
                                          inet_sk(sk)->inet_rcv_saddr,
                                          inet_sk(sk)->inet_num);
        return inet_lhash2_bucket(h, hash);
}

static inline int compute_score(struct sock *sk, const struct net *net,
                                const unsigned short hnum, const __be32 daddr,
                                const int dif, const int sdif)
{
        int score = -1;

        if (net_eq(sock_net(sk), net) && READ_ONCE(sk->sk_num) == hnum &&
                        !ipv6_only_sock(sk)) {
                if (sk->sk_rcv_saddr != daddr)
                        return -1;

                if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))
                        return -1;
                score =  sk->sk_bound_dev_if ? 2 : 1;

                if (sk->sk_family == PF_INET)
                        score++;
                if (READ_ONCE(sk->sk_incoming_cpu) == raw_smp_processor_id())
                        score++;
        }
        return score;
}

/**
 * inet_lookup_reuseport() - execute reuseport logic on AF_INET socket if necessary.
 * @net: network namespace.
 * @sk: AF_INET socket, must be in TCP_LISTEN state for TCP or TCP_CLOSE for UDP.
 * @skb: context for a potential SK_REUSEPORT program.
 * @doff: header offset.
 * @saddr: source address.
 * @sport: source port.
 * @daddr: destination address.
 * @hnum: destination port in host byte order.
 * @ehashfn: hash function used to generate the fallback hash.
 *
 * Return: NULL if sk doesn't have SO_REUSEPORT set, otherwise a pointer to
 *         the selected sock or an error.
 */
struct sock *inet_lookup_reuseport(const struct net *net, struct sock *sk,
                                   struct sk_buff *skb, int doff,
                                   __be32 saddr, __be16 sport,
                                   __be32 daddr, unsigned short hnum,
                                   inet_ehashfn_t *ehashfn)
{
        struct sock *reuse_sk = NULL;
        u32 phash;

        if (sk->sk_reuseport) {
                phash = INDIRECT_CALL_2(ehashfn, udp_ehashfn, inet_ehashfn,
                                        net, daddr, hnum, saddr, sport);
                reuse_sk = reuseport_select_sock(sk, phash, skb, doff);
        }
        return reuse_sk;
}
EXPORT_SYMBOL_GPL(inet_lookup_reuseport);

/*
 * Here are some nice properties to exploit here. The BSD API
 * does not allow a listening sock to specify the remote port nor the
 * remote address for the connection. So always assume those are both
 * wildcarded during the search since they can never be otherwise.
 */

/* called with rcu_read_lock() : No refcount taken on the socket */
static struct sock *inet_lhash2_lookup(const struct net *net,
                                struct inet_listen_hashbucket *ilb2,
                                struct sk_buff *skb, int doff,
                                const __be32 saddr, __be16 sport,
                                const __be32 daddr, const unsigned short hnum,
                                const int dif, const int sdif)
{
        struct sock *sk, *result = NULL;
        struct hlist_nulls_node *node;
        int score, hiscore = 0;

        sk_nulls_for_each_rcu(sk, node, &ilb2->nulls_head) {
                score = compute_score(sk, net, hnum, daddr, dif, sdif);
                if (score > hiscore) {
                        result = inet_lookup_reuseport(net, sk, skb, doff,
                                                       saddr, sport, daddr, hnum, inet_ehashfn);
                        if (result)
                                return result;

                        result = sk;
                        hiscore = score;
                }
        }

        return result;
}

struct sock *inet_lookup_run_sk_lookup(const struct net *net,
                                       int protocol,
                                       struct sk_buff *skb, int doff,
                                       __be32 saddr, __be16 sport,
                                       __be32 daddr, u16 hnum, const int dif,
                                       inet_ehashfn_t *ehashfn)
{
        struct sock *sk, *reuse_sk;
        bool no_reuseport;

        no_reuseport = bpf_sk_lookup_run_v4(net, protocol, saddr, sport,
                                            daddr, hnum, dif, &sk);
        if (no_reuseport || IS_ERR_OR_NULL(sk))
                return sk;

        reuse_sk = inet_lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum,
                                         ehashfn);
        if (reuse_sk)
                sk = reuse_sk;
        return sk;
}

struct sock *__inet_lookup_listener(const struct net *net,
                                    struct sk_buff *skb, int doff,
                                    const __be32 saddr, __be16 sport,
                                    const __be32 daddr, const unsigned short hnum,
                                    const int dif, const int sdif)
{
        struct inet_listen_hashbucket *ilb2;
        struct inet_hashinfo *hashinfo;
        struct sock *result = NULL;
        unsigned int hash2;

        /* Lookup redirect from BPF */
        if (static_branch_unlikely(&bpf_sk_lookup_enabled)) {
                result = inet_lookup_run_sk_lookup(net, IPPROTO_TCP, skb, doff,
                                                   saddr, sport, daddr, hnum, dif,
                                                   inet_ehashfn);
                if (result)
                        goto done;
        }

        hashinfo = net->ipv4.tcp_death_row.hashinfo;
        hash2 = ipv4_portaddr_hash(net, daddr, hnum);
        ilb2 = inet_lhash2_bucket(hashinfo, hash2);

        result = inet_lhash2_lookup(net, ilb2, skb, doff,
                                    saddr, sport, daddr, hnum,
                                    dif, sdif);
        if (result)
                goto done;

        /* Lookup lhash2 with INADDR_ANY */
        hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum);
        ilb2 = inet_lhash2_bucket(hashinfo, hash2);

        result = inet_lhash2_lookup(net, ilb2, skb, doff,
                                    saddr, sport, htonl(INADDR_ANY), hnum,
                                    dif, sdif);
done:
        if (IS_ERR(result))
                return NULL;
        return result;
}
EXPORT_SYMBOL_GPL(__inet_lookup_listener);

/* All sockets share common refcount, but have different destructors */
void sock_gen_put(struct sock *sk)
{
        if (!refcount_dec_and_test(&sk->sk_refcnt))
                return;

        if (sk->sk_state == TCP_TIME_WAIT)
                inet_twsk_free(inet_twsk(sk));
        else if (sk->sk_state == TCP_NEW_SYN_RECV)
                reqsk_free(inet_reqsk(sk));
        else
                sk_free(sk);
}
EXPORT_SYMBOL_GPL(sock_gen_put);

void sock_edemux(struct sk_buff *skb)
{
        sock_gen_put(skb->sk);
}
EXPORT_SYMBOL(sock_edemux);

struct sock *__inet_lookup_established(const struct net *net,
                                       const __be32 saddr, const __be16 sport,
                                       const __be32 daddr, const u16 hnum,
                                       const int dif, const int sdif)
{
        const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
        INET_ADDR_COOKIE(acookie, saddr, daddr);
        const struct hlist_nulls_node *node;
        struct inet_ehash_bucket *head;
        struct inet_hashinfo *hashinfo;
        unsigned int hash, slot;
        struct sock *sk;

        hashinfo = net->ipv4.tcp_death_row.hashinfo;
        hash = inet_ehashfn(net, daddr, hnum, saddr, sport);
        slot = hash & hashinfo->ehash_mask;
        head = &hashinfo->ehash[slot];

begin:
        sk_nulls_for_each_rcu(sk, node, &head->chain) {
                if (sk->sk_hash != hash)
                        continue;
                if (likely(inet_match(net, sk, acookie, ports, dif, sdif))) {
                        if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
                                goto out;
                        if (unlikely(!inet_match(net, sk, acookie,
                                                 ports, dif, sdif))) {
                                sock_gen_put(sk);
                                goto begin;
                        }
                        goto found;
                }
        }
        /*
         * if the nulls value we got at the end of this lookup is
         * not the expected one, we must restart lookup.
         * We probably met an item that was moved to another chain.
         */
        if (get_nulls_value(node) != slot)
                goto begin;
out:
        sk = NULL;
found:
        return sk;
}
EXPORT_SYMBOL_GPL(__inet_lookup_established);

/* called with local bh disabled */
static int __inet_check_established(struct inet_timewait_death_row *death_row,
                                    struct sock *sk, __u16 lport,
                                    struct inet_timewait_sock **twp,
                                    bool rcu_lookup,
                                    u32 hash)
{
        struct inet_hashinfo *hinfo = death_row->hashinfo;
        struct inet_sock *inet = inet_sk(sk);
        __be32 daddr = inet->inet_rcv_saddr;
        __be32 saddr = inet->inet_daddr;
        int dif = sk->sk_bound_dev_if;
        struct net *net = sock_net(sk);
        int sdif = l3mdev_master_ifindex_by_index(net, dif);
        INET_ADDR_COOKIE(acookie, saddr, daddr);
        const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
        struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
        struct inet_timewait_sock *tw = NULL;
        const struct hlist_nulls_node *node;
        struct sock *sk2;
        spinlock_t *lock;

        if (rcu_lookup) {
                sk_nulls_for_each(sk2, node, &head->chain) {
                        if (sk2->sk_hash != hash ||
                            !inet_match(net, sk2, acookie, ports, dif, sdif))
                                continue;
                        if (sk2->sk_state == TCP_TIME_WAIT)
                                break;
                        return -EADDRNOTAVAIL;
                }
                return 0;
        }

        lock = inet_ehash_lockp(hinfo, hash);
        spin_lock(lock);

        sk_nulls_for_each(sk2, node, &head->chain) {
                if (sk2->sk_hash != hash)
                        continue;

                if (likely(inet_match(net, sk2, acookie, ports, dif, sdif))) {
                        if (sk2->sk_state == TCP_TIME_WAIT) {
                                tw = inet_twsk(sk2);
                                if (tcp_twsk_unique(sk, sk2, twp))
                                        break;
                        }
                        goto not_unique;
                }
        }

        /* Must record num and sport now. Otherwise we will see
         * in hash table socket with a funny identity.
         */
        inet->inet_num = lport;
        inet->inet_sport = htons(lport);
        sk->sk_hash = hash;
        WARN_ON(!sk_unhashed(sk));
        __sk_nulls_add_node_rcu(sk, &head->chain);
        if (tw) {
                sk_nulls_del_node_init_rcu((struct sock *)tw);
                __NET_INC_STATS(net, LINUX_MIB_TIMEWAITRECYCLED);
        }
        spin_unlock(lock);
        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);

        if (twp) {
                *twp = tw;
        } else if (tw) {
                /* Silly. Should hash-dance instead... */
                inet_twsk_deschedule_put(tw);
        }
        return 0;

not_unique:
        spin_unlock(lock);
        return -EADDRNOTAVAIL;
}

static u64 inet_sk_port_offset(const struct sock *sk)
{
        const struct inet_sock *inet = inet_sk(sk);

        return secure_ipv4_port_ephemeral(inet->inet_rcv_saddr,
                                          inet->inet_daddr,
                                          inet->inet_dport);
}

/* Searches for an exsiting socket in the ehash bucket list.
 * Returns true if found, false otherwise.
 */
static bool inet_ehash_lookup_by_sk(struct sock *sk,
                                    struct hlist_nulls_head *list)
{
        const __portpair ports = INET_COMBINED_PORTS(sk->sk_dport, sk->sk_num);
        const int sdif = sk->sk_bound_dev_if;
        const int dif = sk->sk_bound_dev_if;
        const struct hlist_nulls_node *node;
        struct net *net = sock_net(sk);
        struct sock *esk;

        INET_ADDR_COOKIE(acookie, sk->sk_daddr, sk->sk_rcv_saddr);

        sk_nulls_for_each_rcu(esk, node, list) {
                if (esk->sk_hash != sk->sk_hash)
                        continue;
                if (sk->sk_family == AF_INET) {
                        if (unlikely(inet_match(net, esk, acookie,
                                                ports, dif, sdif))) {
                                return true;
                        }
                }
#if IS_ENABLED(CONFIG_IPV6)
                else if (sk->sk_family == AF_INET6) {
                        if (unlikely(inet6_match(net, esk,
                                                 &sk->sk_v6_daddr,
                                                 &sk->sk_v6_rcv_saddr,
                                                 ports, dif, sdif))) {
                                return true;
                        }
                }
#endif
        }
        return false;
}

/* Insert a socket into ehash, and eventually remove another one
 * (The another one can be a SYN_RECV or TIMEWAIT)
 * If an existing socket already exists, socket sk is not inserted,
 * and sets found_dup_sk parameter to true.
 */
bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk)
{
        struct inet_hashinfo *hashinfo = tcp_get_hashinfo(sk);
        struct inet_ehash_bucket *head;
        struct hlist_nulls_head *list;
        spinlock_t *lock;
        bool ret = true;

        WARN_ON_ONCE(!sk_unhashed(sk));

        sk->sk_hash = sk_ehashfn(sk);
        head = inet_ehash_bucket(hashinfo, sk->sk_hash);
        list = &head->chain;
        lock = inet_ehash_lockp(hashinfo, sk->sk_hash);

        spin_lock(lock);
        if (osk) {
                WARN_ON_ONCE(sk->sk_hash != osk->sk_hash);
                ret = sk_nulls_replace_node_init_rcu(osk, sk);
                goto unlock;
        }

        if (found_dup_sk) {
                *found_dup_sk = inet_ehash_lookup_by_sk(sk, list);
                if (*found_dup_sk)
                        ret = false;
        }

        if (ret)
                __sk_nulls_add_node_rcu(sk, list);

unlock:
        spin_unlock(lock);

        return ret;
}

bool inet_ehash_nolisten(struct sock *sk, struct sock *osk, bool *found_dup_sk)
{
        bool ok = inet_ehash_insert(sk, osk, found_dup_sk);

        if (ok) {
                sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
        } else {
                tcp_orphan_count_inc();
                inet_sk_set_state(sk, TCP_CLOSE);
                sock_set_flag(sk, SOCK_DEAD);
                inet_csk_destroy_sock(sk);
        }
        return ok;
}
EXPORT_IPV6_MOD(inet_ehash_nolisten);

static int inet_reuseport_add_sock(struct sock *sk,
                                   struct inet_listen_hashbucket *ilb)
{
        struct inet_bind_bucket *tb = inet_csk(sk)->icsk_bind_hash;
        const struct hlist_nulls_node *node;
        kuid_t uid = sk_uid(sk);
        struct sock *sk2;

        sk_nulls_for_each_rcu(sk2, node, &ilb->nulls_head) {
                if (sk2 != sk &&
                    sk2->sk_family == sk->sk_family &&
                    ipv6_only_sock(sk2) == ipv6_only_sock(sk) &&
                    sk2->sk_bound_dev_if == sk->sk_bound_dev_if &&
                    inet_csk(sk2)->icsk_bind_hash == tb &&
                    sk2->sk_reuseport && uid_eq(uid, sk_uid(sk2)) &&
                    inet_rcv_saddr_equal(sk, sk2, false))
                        return reuseport_add_sock(sk, sk2,
                                                  inet_rcv_saddr_any(sk));
        }

        return reuseport_alloc(sk, inet_rcv_saddr_any(sk));
}

int inet_hash(struct sock *sk)
{
        struct inet_hashinfo *hashinfo = tcp_get_hashinfo(sk);
        struct inet_listen_hashbucket *ilb2;
        int err = 0;

        if (sk->sk_state == TCP_CLOSE)
                return 0;

        if (sk->sk_state != TCP_LISTEN) {
                local_bh_disable();
                inet_ehash_nolisten(sk, NULL, NULL);
                local_bh_enable();
                return 0;
        }
        WARN_ON(!sk_unhashed(sk));
        ilb2 = inet_lhash2_bucket_sk(hashinfo, sk);

        spin_lock(&ilb2->lock);
        if (sk->sk_reuseport) {
                err = inet_reuseport_add_sock(sk, ilb2);
                if (err)
                        goto unlock;
        }
        sock_set_flag(sk, SOCK_RCU_FREE);
        if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
                sk->sk_family == AF_INET6)
                __sk_nulls_add_node_tail_rcu(sk, &ilb2->nulls_head);
        else
                __sk_nulls_add_node_rcu(sk, &ilb2->nulls_head);
        sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
unlock:
        spin_unlock(&ilb2->lock);

        return err;
}
EXPORT_IPV6_MOD(inet_hash);

void inet_unhash(struct sock *sk)
{
        struct inet_hashinfo *hashinfo = tcp_get_hashinfo(sk);

        if (sk_unhashed(sk))
                return;

        sock_rps_delete_flow(sk);
        if (sk->sk_state == TCP_LISTEN) {
                struct inet_listen_hashbucket *ilb2;

                ilb2 = inet_lhash2_bucket_sk(hashinfo, sk);
                /* Don't disable bottom halves while acquiring the lock to
                 * avoid circular locking dependency on PREEMPT_RT.
                 */
                spin_lock(&ilb2->lock);
                if (rcu_access_pointer(sk->sk_reuseport_cb))
                        reuseport_stop_listen_sock(sk);

                __sk_nulls_del_node_init_rcu(sk);
                sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
                spin_unlock(&ilb2->lock);
        } else {
                spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash);

                spin_lock_bh(lock);
                __sk_nulls_del_node_init_rcu(sk);
                sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
                spin_unlock_bh(lock);
        }
}
EXPORT_IPV6_MOD(inet_unhash);

static bool inet_bind2_bucket_match(const struct inet_bind2_bucket *tb,
                                    const struct net *net, unsigned short port,
                                    int l3mdev, const struct sock *sk)
{
        if (!net_eq(ib2_net(tb), net) || tb->port != port ||
            tb->l3mdev != l3mdev)
                return false;

        return inet_bind2_bucket_addr_match(tb, sk);
}

bool inet_bind2_bucket_match_addr_any(const struct inet_bind2_bucket *tb, const struct net *net,
                                      unsigned short port, int l3mdev, const struct sock *sk)
{
        if (!net_eq(ib2_net(tb), net) || tb->port != port ||
            tb->l3mdev != l3mdev)
                return false;

#if IS_ENABLED(CONFIG_IPV6)
        if (tb->addr_type == IPV6_ADDR_ANY)
                return true;

        if (tb->addr_type != IPV6_ADDR_MAPPED)
                return false;

        if (sk->sk_family == AF_INET6 &&
            !ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr))
                return false;
#endif
        return tb->rcv_saddr == 0;
}

/* The socket's bhash2 hashbucket spinlock must be held when this is called */
struct inet_bind2_bucket *
inet_bind2_bucket_find(const struct inet_bind_hashbucket *head, const struct net *net,
                       unsigned short port, int l3mdev, const struct sock *sk)
{
        struct inet_bind2_bucket *bhash2 = NULL;

        inet_bind_bucket_for_each(bhash2, &head->chain)
                if (inet_bind2_bucket_match(bhash2, net, port, l3mdev, sk))
                        break;

        return bhash2;
}

struct inet_bind_hashbucket *
inet_bhash2_addr_any_hashbucket(const struct sock *sk, const struct net *net, int port)
{
        struct inet_hashinfo *hinfo = tcp_get_hashinfo(sk);
        u32 hash;

#if IS_ENABLED(CONFIG_IPV6)
        if (sk->sk_family == AF_INET6)
                hash = ipv6_portaddr_hash(net, &in6addr_any, port);
        else
#endif
                hash = ipv4_portaddr_hash(net, 0, port);

        return &hinfo->bhash2[hash & (hinfo->bhash_size - 1)];
}

static void inet_update_saddr(struct sock *sk, void *saddr, int family)
{
        if (family == AF_INET) {
                inet_sk(sk)->inet_saddr = *(__be32 *)saddr;
                sk_rcv_saddr_set(sk, inet_sk(sk)->inet_saddr);
        }
#if IS_ENABLED(CONFIG_IPV6)
        else {
                sk->sk_v6_rcv_saddr = *(struct in6_addr *)saddr;
        }
#endif
}

static int __inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family, bool reset)
{
        struct inet_hashinfo *hinfo = tcp_get_hashinfo(sk);
        struct inet_bind_hashbucket *head, *head2;
        struct inet_bind2_bucket *tb2, *new_tb2;
        int l3mdev = inet_sk_bound_l3mdev(sk);
        int port = inet_sk(sk)->inet_num;
        struct net *net = sock_net(sk);
        int bhash;

        if (!inet_csk(sk)->icsk_bind2_hash) {
                /* Not bind()ed before. */
                if (reset)
                        inet_reset_saddr(sk);
                else
                        inet_update_saddr(sk, saddr, family);

                return 0;
        }

        /* Allocate a bind2 bucket ahead of time to avoid permanently putting
         * the bhash2 table in an inconsistent state if a new tb2 bucket
         * allocation fails.
         */
        new_tb2 = kmem_cache_alloc(hinfo->bind2_bucket_cachep, GFP_ATOMIC);
        if (!new_tb2) {
                if (reset) {
                        /* The (INADDR_ANY, port) bucket might have already
                         * been freed, then we cannot fixup icsk_bind2_hash,
                         * so we give up and unlink sk from bhash/bhash2 not
                         * to leave inconsistency in bhash2.
                         */
                        inet_put_port(sk);
                        inet_reset_saddr(sk);
                }

                return -ENOMEM;
        }

        bhash = inet_bhashfn(net, port, hinfo->bhash_size);
        head = &hinfo->bhash[bhash];
        head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);

        /* If we change saddr locklessly, another thread
         * iterating over bhash might see corrupted address.
         */
        spin_lock_bh(&head->lock);

        spin_lock(&head2->lock);
        __sk_del_bind_node(sk);
        inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep, inet_csk(sk)->icsk_bind2_hash);
        spin_unlock(&head2->lock);

        if (reset)
                inet_reset_saddr(sk);
        else
                inet_update_saddr(sk, saddr, family);

        head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);

        spin_lock(&head2->lock);
        tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
        if (!tb2) {
                tb2 = new_tb2;
                inet_bind2_bucket_init(tb2, net, head2, inet_csk(sk)->icsk_bind_hash, sk);
                if (sk_is_connect_bind(sk)) {
                        tb2->fastreuse = -1;
                        tb2->fastreuseport = -1;
                }
        }
        inet_csk(sk)->icsk_bind2_hash = tb2;
        sk_add_bind_node(sk, &tb2->owners);
        spin_unlock(&head2->lock);

        spin_unlock_bh(&head->lock);

        if (tb2 != new_tb2)
                kmem_cache_free(hinfo->bind2_bucket_cachep, new_tb2);

        return 0;
}

int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
{
        return __inet_bhash2_update_saddr(sk, saddr, family, false);
}
EXPORT_IPV6_MOD(inet_bhash2_update_saddr);

void inet_bhash2_reset_saddr(struct sock *sk)
{
        if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
                __inet_bhash2_update_saddr(sk, NULL, 0, true);
}
EXPORT_IPV6_MOD(inet_bhash2_reset_saddr);

/* RFC 6056 3.3.4.  Algorithm 4: Double-Hash Port Selection Algorithm
 * Note that we use 32bit integers (vs RFC 'short integers')
 * because 2^16 is not a multiple of num_ephemeral and this
 * property might be used by clever attacker.
 *
 * RFC claims using TABLE_LENGTH=10 buckets gives an improvement, though
 * attacks were since demonstrated, thus we use 65536 by default instead
 * to really give more isolation and privacy, at the expense of 256kB
 * of kernel memory.
 */
#define INET_TABLE_PERTURB_SIZE (1 << CONFIG_INET_TABLE_PERTURB_ORDER)
static u32 *table_perturb;

int __inet_hash_connect(struct inet_timewait_death_row *death_row,
                struct sock *sk, u64 port_offset,
                u32 hash_port0,
                int (*check_established)(struct inet_timewait_death_row *,
                        struct sock *, __u16, struct inet_timewait_sock **,
                        bool rcu_lookup, u32 hash))
{
        struct inet_hashinfo *hinfo = death_row->hashinfo;
        struct inet_bind_hashbucket *head, *head2;
        struct inet_timewait_sock *tw = NULL;
        int port = inet_sk(sk)->inet_num;
        struct net *net = sock_net(sk);
        struct inet_bind2_bucket *tb2;
        struct inet_bind_bucket *tb;
        bool tb_created = false;
        u32 remaining, offset;
        int ret, i, low, high;
        bool local_ports;
        int step, l3mdev;
        u32 index;

        if (port) {
                local_bh_disable();
                ret = check_established(death_row, sk, port, NULL, false,
                                        hash_port0 + port);
                local_bh_enable();
                return ret;
        }

        l3mdev = inet_sk_bound_l3mdev(sk);

        local_ports = inet_sk_get_local_port_range(sk, &low, &high);
        step = local_ports ? 1 : 2;

        high++; /* [32768, 60999] -> [32768, 61000[ */
        remaining = high - low;
        if (!local_ports && remaining > 1)
                remaining &= ~1U;

        get_random_sleepable_once(table_perturb,
                                  INET_TABLE_PERTURB_SIZE * sizeof(*table_perturb));
        index = port_offset & (INET_TABLE_PERTURB_SIZE - 1);

        offset = READ_ONCE(table_perturb[index]) + (port_offset >> 32);
        offset %= remaining;

        /* In first pass we try ports of @low parity.
         * inet_csk_get_port() does the opposite choice.
         */
        if (!local_ports)
                offset &= ~1U;
other_parity_scan:
        port = low + offset;
        for (i = 0; i < remaining; i += step, port += step) {
                if (unlikely(port >= high))
                        port -= remaining;
                if (inet_is_local_reserved_port(net, port))
                        continue;
                head = &hinfo->bhash[inet_bhashfn(net, port,
                                                  hinfo->bhash_size)];
                rcu_read_lock();
                hlist_for_each_entry_rcu(tb, &head->chain, node) {
                        if (!inet_bind_bucket_match(tb, net, port, l3mdev))
                                continue;
                        if (tb->fastreuse >= 0 || tb->fastreuseport >= 0) {
                                rcu_read_unlock();
                                goto next_port;
                        }
                        if (!check_established(death_row, sk, port, &tw, true,
                                               hash_port0 + port))
                                break;
                        rcu_read_unlock();
                        goto next_port;
                }
                rcu_read_unlock();

                spin_lock_bh(&head->lock);

                /* Does not bother with rcv_saddr checks, because
                 * the established check is already unique enough.
                 */
                inet_bind_bucket_for_each(tb, &head->chain) {
                        if (inet_bind_bucket_match(tb, net, port, l3mdev)) {
                                if (tb->fastreuse >= 0 ||
                                    tb->fastreuseport >= 0)
                                        goto next_port_unlock;
                                WARN_ON(hlist_empty(&tb->bhash2));
                                if (!check_established(death_row, sk,
                                                       port, &tw, false,
                                                       hash_port0 + port))
                                        goto ok;
                                goto next_port_unlock;
                        }
                }

                tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
                                             net, head, port, l3mdev);
                if (!tb) {
                        spin_unlock_bh(&head->lock);
                        return -ENOMEM;
                }
                tb_created = true;
                tb->fastreuse = -1;
                tb->fastreuseport = -1;
                goto ok;
next_port_unlock:
                spin_unlock_bh(&head->lock);
next_port:
                cond_resched();
        }

        if (!local_ports) {
                offset++;
                if ((offset & 1) && remaining > 1)
                        goto other_parity_scan;
        }
        return -EADDRNOTAVAIL;

ok:
        /* Find the corresponding tb2 bucket since we need to
         * add the socket to the bhash2 table as well
         */
        head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
        spin_lock(&head2->lock);

        tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
        if (!tb2) {
                tb2 = inet_bind2_bucket_create(hinfo->bind2_bucket_cachep, net,
                                               head2, tb, sk);
                if (!tb2)
                        goto error;
                tb2->fastreuse = -1;
                tb2->fastreuseport = -1;
        }

        /* Here we want to add a little bit of randomness to the next source
         * port that will be chosen. We use a max() with a random here so that
         * on low contention the randomness is maximal and on high contention
         * it may be inexistent.
         */
        i = max_t(int, i, get_random_u32_below(8) * step);
        WRITE_ONCE(table_perturb[index], READ_ONCE(table_perturb[index]) + i + step);

        /* Head lock still held and bh's disabled */
        inet_bind_hash(sk, tb, tb2, port);
        sk->sk_userlocks |= SOCK_CONNECT_BIND;

        if (sk_unhashed(sk)) {
                inet_sk(sk)->inet_sport = htons(port);
                inet_ehash_nolisten(sk, (struct sock *)tw, NULL);
        }
        if (tw)
                inet_twsk_bind_unhash(tw, hinfo);

        spin_unlock(&head2->lock);
        spin_unlock(&head->lock);

        if (tw)
                inet_twsk_deschedule_put(tw);
        local_bh_enable();
        return 0;

error:
        if (sk_hashed(sk)) {
                spinlock_t *lock = inet_ehash_lockp(hinfo, sk->sk_hash);

                sock_prot_inuse_add(net, sk->sk_prot, -1);

                spin_lock(lock);
                __sk_nulls_del_node_init_rcu(sk);
                spin_unlock(lock);

                sk->sk_hash = 0;
                inet_sk(sk)->inet_sport = 0;
                WRITE_ONCE(inet_sk(sk)->inet_num, 0);

                if (tw)
                        inet_twsk_bind_unhash(tw, hinfo);
        }

        spin_unlock(&head2->lock);
        if (tb_created)
                inet_bind_bucket_destroy(tb);
        spin_unlock(&head->lock);

        if (tw)
                inet_twsk_deschedule_put(tw);

        local_bh_enable();

        return -ENOMEM;
}

/*
 * Bind a port for a connect operation and hash it.
 */
int inet_hash_connect(struct inet_timewait_death_row *death_row,
                      struct sock *sk)
{
        const struct inet_sock *inet = inet_sk(sk);
        const struct net *net = sock_net(sk);
        u64 port_offset = 0;
        u32 hash_port0;

        if (!inet_sk(sk)->inet_num)
                port_offset = inet_sk_port_offset(sk);

        hash_port0 = inet_ehashfn(net, inet->inet_rcv_saddr, 0,
                                  inet->inet_daddr, inet->inet_dport);

        return __inet_hash_connect(death_row, sk, port_offset, hash_port0,
                                   __inet_check_established);
}

static void init_hashinfo_lhash2(struct inet_hashinfo *h)
{
        int i;

        for (i = 0; i <= h->lhash2_mask; i++) {
                spin_lock_init(&h->lhash2[i].lock);
                INIT_HLIST_NULLS_HEAD(&h->lhash2[i].nulls_head,
                                      i + LISTENING_NULLS_BASE);
        }
}

void __init inet_hashinfo2_init(struct inet_hashinfo *h, const char *name,
                                unsigned long numentries, int scale,
                                unsigned long low_limit,
                                unsigned long high_limit)
{
        h->lhash2 = alloc_large_system_hash(name,
                                            sizeof(*h->lhash2),
                                            numentries,
                                            scale,
                                            0,
                                            NULL,
                                            &h->lhash2_mask,
                                            low_limit,
                                            high_limit);
        init_hashinfo_lhash2(h);

        /* this one is used for source ports of outgoing connections */
        table_perturb = alloc_large_system_hash("Table-perturb",
                                                sizeof(*table_perturb),
                                                INET_TABLE_PERTURB_SIZE,
                                                0, 0, NULL, NULL,
                                                INET_TABLE_PERTURB_SIZE,
                                                INET_TABLE_PERTURB_SIZE);
}

int inet_hashinfo2_init_mod(struct inet_hashinfo *h)
{
        h->lhash2 = kmalloc_objs(*h->lhash2, INET_LHTABLE_SIZE);
        if (!h->lhash2)
                return -ENOMEM;

        h->lhash2_mask = INET_LHTABLE_SIZE - 1;
        /* INET_LHTABLE_SIZE must be a power of 2 */
        BUG_ON(INET_LHTABLE_SIZE & h->lhash2_mask);

        init_hashinfo_lhash2(h);
        return 0;
}

int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
{
        unsigned int locksz = sizeof(spinlock_t);
        unsigned int i, nblocks = 1;
        spinlock_t *ptr = NULL;

        if (locksz == 0)
                goto set_mask;

        /* Allocate 2 cache lines or at least one spinlock per cpu. */
        nblocks = max(2U * L1_CACHE_BYTES / locksz, 1U) * num_possible_cpus();

        /* At least one page per NUMA node. */
        nblocks = max(nblocks, num_online_nodes() * PAGE_SIZE / locksz);

        nblocks = roundup_pow_of_two(nblocks);

        /* No more locks than number of hash buckets. */
        nblocks = min(nblocks, hashinfo->ehash_mask + 1);

        if (num_online_nodes() > 1) {
                /* Use vmalloc() to allow NUMA policy to spread pages
                 * on all available nodes if desired.
                 */
                ptr = vmalloc_array(nblocks, locksz);
        }
        if (!ptr) {
                ptr = kvmalloc_array(nblocks, locksz, GFP_KERNEL);
                if (!ptr)
                        return -ENOMEM;
        }
        for (i = 0; i < nblocks; i++)
                spin_lock_init(&ptr[i]);
        hashinfo->ehash_locks = ptr;
set_mask:
        hashinfo->ehash_locks_mask = nblocks - 1;
        return 0;
}

struct inet_hashinfo *inet_pernet_hashinfo_alloc(struct inet_hashinfo *hashinfo,
                                                 unsigned int ehash_entries)
{
        struct inet_hashinfo *new_hashinfo;
        int i;

        new_hashinfo = kmemdup(hashinfo, sizeof(*hashinfo), GFP_KERNEL);
        if (!new_hashinfo)
                goto err;

        new_hashinfo->ehash = vmalloc_huge(ehash_entries * sizeof(struct inet_ehash_bucket),
                                           GFP_KERNEL_ACCOUNT);
        if (!new_hashinfo->ehash)
                goto free_hashinfo;

        new_hashinfo->ehash_mask = ehash_entries - 1;

        if (inet_ehash_locks_alloc(new_hashinfo))
                goto free_ehash;

        for (i = 0; i < ehash_entries; i++)
                INIT_HLIST_NULLS_HEAD(&new_hashinfo->ehash[i].chain, i);

        new_hashinfo->pernet = true;

        return new_hashinfo;

free_ehash:
        vfree(new_hashinfo->ehash);
free_hashinfo:
        kfree(new_hashinfo);
err:
        return NULL;
}

void inet_pernet_hashinfo_free(struct inet_hashinfo *hashinfo)
{
        if (!hashinfo->pernet)
                return;

        inet_ehash_locks_free(hashinfo);
        vfree(hashinfo->ehash);
        kfree(hashinfo);
}