kernel-ark/net/ipv6/inet6_hashtables.c
Stephen Hemminger 227b60f510 [INET]: local port range robustness
Expansion of original idea from Denis V. Lunev <den@openvz.org>

Add robustness and locking to the local_port_range sysctl.
1. Enforce that low < high when setting.
2. Use seqlock to ensure atomic update.

The locking might seem like overkill, but there are
cases where sysadmin might want to change value in the
middle of a DoS attack.

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2007-10-10 17:30:46 -07:00

344 lines
8.9 KiB
C

/*
* 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 <acme@mandriva.com>
*
* 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/ip.h>
void __inet6_hash(struct inet_hashinfo *hashinfo,
struct sock *sk)
{
struct hlist_head *list;
rwlock_t *lock;
BUG_TRAP(sk_unhashed(sk));
if (sk->sk_state == TCP_LISTEN) {
list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
lock = &hashinfo->lhash_lock;
inet_listen_wlock(hashinfo);
} else {
unsigned int hash;
sk->sk_hash = hash = inet6_sk_ehashfn(sk);
hash &= (hashinfo->ehash_size - 1);
list = &hashinfo->ehash[hash].chain;
lock = &hashinfo->ehash[hash].lock;
write_lock(lock);
}
__sk_add_node(sk, list);
sock_prot_inc_use(sk->sk_prot);
write_unlock(lock);
}
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 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_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(daddr, hnum, saddr, sport);
struct inet_ehash_bucket *head = inet_ehash_bucket(hashinfo, hash);
prefetch(head->chain.first);
read_lock(&head->lock);
sk_for_each(sk, node, &head->chain) {
/* For IPV6 do the cheaper port and family tests first. */
if (INET6_MATCH(sk, hash, saddr, daddr, ports, dif))
goto hit; /* You sunk my battleship! */
}
/* Must check for a TIME_WAIT'er before going to listener hash. */
sk_for_each(sk, node, &head->twchain) {
const struct inet_timewait_sock *tw = inet_twsk(sk);
if(*((__portpair *)&(tw->tw_dport)) == ports &&
sk->sk_family == PF_INET6) {
const struct inet6_timewait_sock *tw6 = inet6_twsk(sk);
if (ipv6_addr_equal(&tw6->tw_v6_daddr, saddr) &&
ipv6_addr_equal(&tw6->tw_v6_rcv_saddr, daddr) &&
(!sk->sk_bound_dev_if || sk->sk_bound_dev_if == dif))
goto hit;
}
}
read_unlock(&head->lock);
return NULL;
hit:
sock_hold(sk);
read_unlock(&head->lock);
return sk;
}
EXPORT_SYMBOL(__inet6_lookup_established);
struct sock *inet6_lookup_listener(struct inet_hashinfo *hashinfo,
const struct in6_addr *daddr,
const unsigned short hnum, const int dif)
{
struct sock *sk;
const struct hlist_node *node;
struct sock *result = NULL;
int score, hiscore = 0;
read_lock(&hashinfo->lhash_lock);
sk_for_each(sk, node, &hashinfo->listening_hash[inet_lhashfn(hnum)]) {
if (inet_sk(sk)->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))
continue;
score++;
}
if (sk->sk_bound_dev_if) {
if (sk->sk_bound_dev_if != dif)
continue;
score++;
}
if (score == 3) {
result = sk;
break;
}
if (score > hiscore) {
hiscore = score;
result = sk;
}
}
}
if (result)
sock_hold(result);
read_unlock(&hashinfo->lhash_lock);
return result;
}
EXPORT_SYMBOL_GPL(inet6_lookup_listener);
struct sock *inet6_lookup(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(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->dport, lport);
const unsigned int hash = inet6_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->twchain) {
const struct inet6_timewait_sock *tw6 = inet6_twsk(sk2);
tw = inet_twsk(sk2);
if(*((__portpair *)&(tw->tw_dport)) == ports &&
sk2->sk_family == PF_INET6 &&
ipv6_addr_equal(&tw6->tw_v6_daddr, saddr) &&
ipv6_addr_equal(&tw6->tw_v6_rcv_saddr, daddr) &&
sk2->sk_bound_dev_if == sk->sk_bound_dev_if) {
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 (INET6_MATCH(sk2, 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->num = lport;
inet->sport = htons(lport);
BUG_TRAP(sk_unhashed(sk));
__sk_add_node(sk, &head->chain);
sk->sk_hash = hash;
sock_prot_inc_use(sk->sk_prot);
write_unlock(&head->lock);
if (twp != NULL) {
*twp = tw;
NET_INC_STATS_BH(LINUX_MIB_TIMEWAITRECYCLED);
} else if (tw != NULL) {
/* 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 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->dport);
}
int inet6_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 == 0) {
int i, port, low, high, remaining;
static u32 hint;
const u32 offset = hint + inet6_sk_port_offset(sk);
struct hlist_node *node;
struct inet_timewait_sock *tw = NULL;
inet_get_local_port_range(&low, &high);
remaining = high - low;
local_bh_disable();
for (i = 1; i <= remaining; i++) {
port = low + (i + offset) % remaining;
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 (!__inet6_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);
__inet6_hash(hinfo, sk);
}
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 == NULL) {
__inet6_hash(hinfo, sk);
spin_unlock_bh(&head->lock);
return 0;
} else {
spin_unlock(&head->lock);
/* No definite answer... Walk to established hash table */
ret = __inet6_check_established(death_row, sk, snum, NULL);
out:
local_bh_enable();
return ret;
}
}
EXPORT_SYMBOL_GPL(inet6_hash_connect);