inet6_hashtables.c

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/*
 * 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 INET6 transport hashtables
 *
 * Authors: Lotsa people, from code originally in tcp, generalised here
 *      by Arnaldo Carvalho de Melo <[email protected]>
 *
 *  This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/random.h>

#include <net/inet_connection_sock.h>
#include <net/inet_hashtables.h>
#include <net/inet6_hashtables.h>
#include <net/secure_seq.h>
#include <net/ip.h>

int __inet6_hash(struct sock *sk, struct inet_timewait_sock *tw)
{
    struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
    int twrefcnt = 0;

    WARN_ON(!sk_unhashed(sk));

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

        ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
        spin_lock(&ilb->lock);
        __sk_nulls_add_node_rcu(sk, &ilb->head);
        spin_unlock(&ilb->lock);
    } else {
        unsigned int hash;
        struct hlist_nulls_head *list;
        spinlock_t *lock;

        sk->sk_hash = hash = inet6_sk_ehashfn(sk);
        list = &inet_ehash_bucket(hashinfo, hash)->chain;
        lock = inet_ehash_lockp(hashinfo, hash);
        spin_lock(lock);
        __sk_nulls_add_node_rcu(sk, list);
        if (tw) {
            WARN_ON(sk->sk_hash != tw->tw_hash);
            twrefcnt = inet_twsk_unhash(tw);
        }
        spin_unlock(lock);
    }

    sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
    return twrefcnt;
}
EXPORT_SYMBOL(__inet6_hash);

/*
 * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
 * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
 *
 * The sockhash lock must be held as a reader here.
 */
struct sock *__inet6_lookup_established(struct net *net,
                    struct inet_hashinfo *hashinfo,
                       const struct in6_addr *saddr,
                       const __be16 sport,
                       const struct in6_addr *daddr,
                       const u16 hnum,
                       const int dif)
{
    struct sock *sk;
    const struct hlist_nulls_node *node;
    const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
    /* Optimize here for direct hit, only listening connections can
     * have wildcards anyways.
     */
    unsigned int hash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
    unsigned int slot = hash & hashinfo->ehash_mask;
    struct inet_ehash_bucket *head = &hashinfo->ehash[slot];


    rcu_read_lock();
begin:
    sk_nulls_for_each_rcu(sk, node, &head->chain) {
        /* For IPV6 do the cheaper port and family tests first. */
        if (INET6_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
            if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt)))
                goto begintw;
            if (!INET6_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
                sock_put(sk);
                goto begin;
            }
        goto out;
        }
    }
    if (get_nulls_value(node) != slot)
        goto begin;

begintw:
    /* Must check for a TIME_WAIT'er before going to listener hash. */
    sk_nulls_for_each_rcu(sk, node, &head->twchain) {
        if (INET6_TW_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
            if (unlikely(!atomic_inc_not_zero(&sk->sk_refcnt))) {
                sk = NULL;
                goto out;
            }
            if (!INET6_TW_MATCH(sk, net, hash, saddr, daddr, ports, dif)) {
                sock_put(sk);
                goto begintw;
            }
            goto out;
        }
    }
    if (get_nulls_value(node) != slot)
        goto begintw;
    sk = NULL;
out:
    rcu_read_unlock();
    return sk;
}
EXPORT_SYMBOL(__inet6_lookup_established);

static inline int compute_score(struct sock *sk, struct net *net,
                const unsigned short hnum,
                const struct in6_addr *daddr,
                const int dif)
{
    int score = -1;

    if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&
        sk->sk_family == PF_INET6) {
        const struct ipv6_pinfo *np = inet6_sk(sk);

        score = 1;
        if (!ipv6_addr_any(&np->rcv_saddr)) {
            if (!ipv6_addr_equal(&np->rcv_saddr, daddr))
                return -1;
            score++;
        }
        if (sk->sk_bound_dev_if) {
            if (sk->sk_bound_dev_if != dif)
                return -1;
            score++;
        }
    }
    return score;
}

struct sock *inet6_lookup_listener(struct net *net,
        struct inet_hashinfo *hashinfo, const struct in6_addr *daddr,
        const unsigned short hnum, const int dif)
{
    struct sock *sk;
    const struct hlist_nulls_node *node;
    struct sock *result;
    int score, hiscore;
    unsigned int hash = inet_lhashfn(net, hnum);
    struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];

    rcu_read_lock();
begin:
    result = NULL;
    hiscore = -1;
    sk_nulls_for_each(sk, node, &ilb->head) {
        score = compute_score(sk, net, hnum, daddr, dif);
        if (score > hiscore) {
            hiscore = score;
            result = sk;
        }
    }
    /*
     * 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) != hash + LISTENING_NULLS_BASE)
        goto begin;
    if (result) {
        if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
            result = NULL;
        else if (unlikely(compute_score(result, net, hnum, daddr,
                  dif) < hiscore)) {
            sock_put(result);
            goto begin;
        }
    }
    rcu_read_unlock();
    return result;
}

EXPORT_SYMBOL_GPL(inet6_lookup_listener);

struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
              const struct in6_addr *saddr, const __be16 sport,
              const struct in6_addr *daddr, const __be16 dport,
              const int dif)
{
    struct sock *sk;

    local_bh_disable();
    sk = __inet6_lookup(net, hashinfo, saddr, sport, daddr, ntohs(dport), dif);
    local_bh_enable();

    return sk;
}

EXPORT_SYMBOL_GPL(inet6_lookup);

static int __inet6_check_established(struct inet_timewait_death_row *death_row,
                     struct sock *sk, const __u16 lport,
                     struct inet_timewait_sock **twp)
{
    struct inet_hashinfo *hinfo = death_row->hashinfo;
    struct inet_sock *inet = inet_sk(sk);
    const struct ipv6_pinfo *np = inet6_sk(sk);
    const struct in6_addr *daddr = &np->rcv_saddr;
    const struct in6_addr *saddr = &np->daddr;
    const int dif = sk->sk_bound_dev_if;
    const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);
    struct net *net = sock_net(sk);
    const unsigned int hash = inet6_ehashfn(net, daddr, lport, saddr,
                        inet->inet_dport);
    struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
    spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
    struct sock *sk2;
    const struct hlist_nulls_node *node;
    struct inet_timewait_sock *tw;
    int twrefcnt = 0;

    spin_lock(lock);

    /* Check TIME-WAIT sockets first. */
    sk_nulls_for_each(sk2, node, &head->twchain) {
        tw = inet_twsk(sk2);

        if (INET6_TW_MATCH(sk2, net, hash, saddr, daddr, ports, dif)) {
            if (twsk_unique(sk, sk2, twp))
                goto unique;
            else
                goto not_unique;
        }
    }
    tw = NULL;

    /* And established part... */
    sk_nulls_for_each(sk2, node, &head->chain) {
        if (INET6_MATCH(sk2, net, hash, saddr, daddr, ports, dif))
            goto not_unique;
    }

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) {
        twrefcnt = inet_twsk_unhash(tw);
        NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
    }
    spin_unlock(lock);
    if (twrefcnt)
        inet_twsk_put(tw);
    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(tw, death_row);

        inet_twsk_put(tw);
    }
    return 0;

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

static inline u32 inet6_sk_port_offset(const struct sock *sk)
{
    const struct inet_sock *inet = inet_sk(sk);
    const struct ipv6_pinfo *np = inet6_sk(sk);
    return secure_ipv6_port_ephemeral(np->rcv_saddr.s6_addr32,
                      np->daddr.s6_addr32,
                      inet->inet_dport);
}

int inet6_hash_connect(struct inet_timewait_death_row *death_row,
               struct sock *sk)
{
    return __inet_hash_connect(death_row, sk, inet6_sk_port_offset(sk),
            __inet6_check_established, __inet6_hash);
}

EXPORT_SYMBOL_GPL(inet6_hash_connect);