/*
* 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
*
* 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 <linux/sched.h>
#include <linux/slab.h>
#include <linux/wait.h>
#include <net/inet_connection_sock.h>
#include <net/inet_hashtables.h>
#include <net/ip.h>
/*
* 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 inet_bind_hashbucket *head,
const unsigned short snum)
{
struct inet_bind_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);
if (tb != NULL) {
tb->port = snum;
tb->fastreuse = 0;
INIT_HLIST_HEAD(&tb->owners);
hlist_add_head(&tb->node, &head->chain);
}
return tb;
}
/*
* Caller must hold hashbucket lock for this tb with local BH disabled
*/
void inet_bind_bucket_destroy(struct kmem_cache *cachep, struct inet_bind_bucket *tb)
{
if (hlist_empty(&tb->owners)) {
__hlist_del(&tb->node);
kmem_cache_free(cachep, tb);
}
}
void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
const unsigned short snum)
{
inet_sk(sk)->num = snum;
sk_add_bind_node(sk, &tb->owners);
inet_csk(sk)->icsk_bind_hash = tb;
}
/*
* Get rid of any references to a local port held by the given sock.
*/
static void __inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk)
{
const int bhash = inet_bhashfn(inet_sk(sk)->num, hashinfo->bhash_size);
struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
struct inet_bind_bucket *tb;
spin_lock(&head->lock);
tb = inet_csk(sk)->icsk_bind_hash;
__sk_del_bind_node(sk);
inet_csk(sk)->icsk_bind_hash = NULL;
inet_sk(sk)->num = 0;
inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
spin_unlock(&head->lock);
}
void inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk)
{
local_bh_disable();
__inet_put_port(hashinfo, sk);
local_bh_enable();
}
EXPORT_SYMBOL(inet_put_port);
/*
* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP.
* Look, when several writers sleep and reader wakes them up, all but one
* immediately hit write lock and grab all the cpus. Exclusive sleep solves
* this, _but_ remember, it adds useless work on UP machines (wake up each
* exclusive lock release). It should be ifdefed really.
*/
void inet_listen_wlock(struct inet_hashinfo *hashinfo)
{
write_lock(&hashinfo->lhash_lock);
if (atomic_read(&hashinfo->lhash_users)) {
DEFINE_WAIT(wait);
for (;;) {
prepare_to_wait_exclusive(&hashinfo->lhash_wait,
&wait, TASK_UNINTERRUPTIBLE);
if (!atomic_read(&hashinfo->lhash_users))
break;
write_unlock_bh(&hashinfo->lhash_lock);
schedule();
write_lock_bh(&hashinfo->lhash_lock);
}
finish_wait(&hashinfo->lhash_wait, &wait);
}
}
EXPORT_SYMBOL(inet_listen_wlock);
/*
* Don't inline this cruft. 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.
*/
static struct sock *inet_lookup_listener_slow(const struct hlist_head *head,
const __be32 daddr,
const unsigned short hnum,
const int dif)
{
struct sock *result = NULL, *sk;
const struct hlist_node *node;
int hiscore = -1;
sk_for_each(sk, node, head) {
const struct inet_sock *inet = inet_sk(sk);
if (inet->num == hnum && !ipv6_only_sock(sk)) {
const __be32 rcv_saddr = inet->rcv_saddr;
int score = sk->sk_family == PF_INET ? 1 : 0;
if (rcv_saddr) {
if (rcv_saddr != daddr)
continue;
score += 2;
}
if (sk->sk_bound_dev_if) {
if (sk->sk_bound_dev_if != dif)
continue;
score += 2;
}
if (score == 5)
return sk;
if (score > hiscore) {
hiscore = score;
result = sk;
}
}
}
return result;
}
/* Optimize the common listener case. */
struct sock *__inet_lookup_listener(struct inet_hashinfo *hashinfo,
const __be32 daddr, const unsigned short hnum,
const int dif)
{
struct sock *sk = NULL;
const struct hlist_head *head;
read_lock(&hashinfo->lhash_lock);
head = &hashinfo->listening_hash[inet_lhashfn(hnum)];
if (!hlist_empty(head)) {
const struct inet_sock *inet = inet_sk((sk = __sk_head(head)));
if (inet->num == hnum && !sk->sk_node.next &&
(!inet->rcv_saddr || inet->rcv_saddr == daddr) &&
(sk->sk_family == PF_INET || !ipv6_only_sock(sk)) &&
!sk->sk_bound_dev_if)
goto sherry_cache;
sk = inet_lookup_listener_slow(head, daddr, hnum, dif);
}
if (sk) {
sherry_cache:
sock_hold(sk);
}
read_unlock(&hashinfo->lhash_lock);
return sk;
}
EXPORT_SYMBOL_GPL(__inet_lookup_listener);
/* 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)
{
struct inet_hashinfo *hinfo = death_row->hashinfo;
struct inet_sock *inet = inet_sk(sk);
__be32 daddr = inet->rcv_saddr;
__be32 saddr = inet->daddr;
int dif = sk->sk_bound_dev_if;
INET_ADDR_COOKIE(acookie, saddr, daddr)
const __portpair ports = INET_COMBINED_PORTS(inet->dport, lport);
unsigned int hash = inet_ehashfn(daddr, lport, saddr, inet->dport);
struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
struct sock *sk2;
const struct hlist_node *node;
struct inet_timewait_sock *tw;
prefetch(head->chain.first);
write_lock(&head->lock);
/* Check TIME-WAIT sockets first. */
sk_for_each(sk2, node, &(head + hinfo->ehash_size)->chain) {
tw = inet_twsk(sk2);
if (INET_TW_MATCH(sk2, hash, acookie, saddr, daddr, ports, dif)) {
if (twsk_unique(sk, sk2, twp))
goto unique;
else
goto not_unique;
}
}
tw = NULL;
/* And established part... */
sk_for_each(sk2, node, &head->chain) {
if (INET_MATCH(sk2, hash, acookie, 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->num = lport;
inet->sport = htons(lport);
sk->sk_hash = hash;
BUG_TRAP(sk_unhashed(sk));
__sk_add_node(sk, &head->chain);
sock_prot_inc_use(sk->sk_prot);
write_unlock(&head->lock);
if (twp) {
*twp = tw;
NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
} else if (tw) {
/* Silly. Should hash-dance instead... */
inet_twsk_deschedule(tw, death_row);
NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
inet_twsk_put(tw);
}
return 0;
not_unique:
write_unlock(&head->lock);
return -EADDRNOTAVAIL;
}
static inline u32 inet_sk_port_offset(const struct sock *sk)
{
const struct inet_sock *inet = inet_sk(sk);
return secure_ipv4_port_ephemeral(inet->rcv_saddr, inet->daddr,
inet->dport);
}
/*
* Bind a port for a connect operation and hash it.
*/
int inet_hash_connect(struct inet_timewait_death_row *death_row,
struct sock *sk)
{
struct inet_hashinfo *hinfo = death_row->hashinfo;
const unsigned short snum = inet_sk(sk)->num;
struct inet_bind_hashbucket *head;
struct inet_bind_bucket *tb;
int ret;
if (!snum) {
int low = sysctl_local_port_range[0];
int high = sysctl_local_port_range[1];
int range = high - low;
int i;
int port;
static u32 hint;
u32 offset = hint + inet_sk_port_offset(sk);
struct hlist_node *node;
struct inet_timewait_sock *tw = NULL;
local_bh_disable();
for (i = 1; i <= range; i++) {
port = low + (i + offset) % range;
head = &hinfo->bhash[inet_bhashfn(port, hinfo->bhash_size)];
spin_lock(&head->lock);
/* Does not bother with rcv_saddr checks,
* because the established check is already
* unique enough.
*/
inet_bind_bucket_for_each(tb, node, &head->chain) {
if (tb->port == port) {
BUG_TRAP(!hlist_empty(&tb->owners));
if (tb->fastreuse >= 0)
goto next_port;
if (!__inet_check_established(death_row,
sk, port,
&tw))
goto ok;
goto next_port;
}
}
tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, head, port);
if (!tb) {
spin_unlock(&head->lock);
break;
}
tb->fastreuse = -1;
goto ok;
next_port:
spin_unlock(&head->lock);
}
local_bh_enable();
return -EADDRNOTAVAIL;
ok:
hint += i;
/* Head lock still held and bh's disabled */
inet_bind_hash(sk, tb, port);
if (sk_unhashed(sk)) {
inet_sk(sk)->sport = htons(port);
__inet_hash(hinfo, sk, 0);
}
spin_unlock(&head->lock);
if (tw) {
inet_twsk_deschedule(tw, death_row);
inet_twsk_put(tw);
}
ret = 0;
goto out;
}
head = &hinfo->bhash[inet_bhashfn(snum, hinfo->bhash_size)];
tb = inet_csk(sk)->icsk_bind_hash;
spin_lock_bh(&head->lock);
if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
__inet_hash(hinfo, sk, 0);
spin_unlock_bh(&head->lock);
return 0;
} else {
spin_unlock(&head->lock);
/* No definite answer... Walk to established hash table */
ret = __inet_check_established(death_row, sk, snum, NULL);
out:
local_bh_enable();
return ret;
}
}
EXPORT_SYMBOL_GPL(inet_hash_connect);
