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linux/net/ipv4/inet_hashtables.c
Joanne Koong 28044fc1d4 net: Add a bhash2 table hashed by port and address 
The current bind hashtable (bhash) is hashed by port only.
In the socket bind path, we have to check for bind conflicts by
traversing the specified port's inet_bind_bucket while holding the
hashbucket's spinlock (see inet_csk_get_port() and
inet_csk_bind_conflict()). In instances where there are tons of
sockets hashed to the same port at different addresses, the bind
conflict check is time-intensive and can cause softirq cpu lockups,
as well as stops new tcp connections since __inet_inherit_port()
also contests for the spinlock.

This patch adds a second bind table, bhash2, that hashes by
port and sk->sk_rcv_saddr (ipv4) and sk->sk_v6_rcv_saddr (ipv6).
Searching the bhash2 table leads to significantly faster conflict
resolution and less time holding the hashbucket spinlock.

Please note a few things:
* There can be the case where the a socket's address changes after it
has been bound. There are two cases where this happens:

  1) The case where there is a bind() call on INADDR_ANY (ipv4) or
  IPV6_ADDR_ANY (ipv6) and then a connect() call. The kernel will
  assign the socket an address when it handles the connect()

  2) In inet_sk_reselect_saddr(), which is called when rebuilding the
  sk header and a few pre-conditions are met (eg rerouting fails).

In these two cases, we need to update the bhash2 table by removing the
entry for the old address, and add a new entry reflecting the updated
address.

* The bhash2 table must have its own lock, even though concurrent
accesses on the same port are protected by the bhash lock. Bhash2 must
have its own lock to protect against cases where sockets on different
ports hash to different bhash hashbuckets but to the same bhash2
hashbucket.

This brings up a few stipulations:
  1) When acquiring both the bhash and the bhash2 lock, the bhash2 lock
  will always be acquired after the bhash lock and released before the
  bhash lock is released.

  2) There are no nested bhash2 hashbucket locks. A bhash2 lock is always
  acquired+released before another bhash2 lock is acquired+released.

* The bhash table cannot be superseded by the bhash2 table because for
bind requests on INADDR_ANY (ipv4) or IPV6_ADDR_ANY (ipv6), every socket
bound to that port must be checked for a potential conflict. The bhash
table is the only source of port->socket associations.

Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2022-08-24 19:30:07 -07:00

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// 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/secure_seq.h>
#include <net/ip.h>
#include <net/tcp.h>
#include <net/sock_reuseport.h>
static u32 inet_ehashfn(const struct net *net, const __be32 laddr,
const __u16 lport, const __be32 faddr,
const __be16 fport)
{
static u32 inet_ehash_secret __read_mostly;
net_get_random_once(&inet_ehash_secret, sizeof(inet_ehash_secret));
return __inet_ehashfn(laddr, lport, faddr, fport,
inet_ehash_secret + net_hash_mix(net));
}
/* 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);
}
/*
* 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->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);
}
}
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 *tb,
struct net *net,
struct inet_bind_hashbucket *head,
unsigned short port, int l3mdev,
const struct sock *sk)
{
write_pnet(&tb->ib_net, net);
tb->l3mdev = l3mdev;
tb->port = port;
#if IS_ENABLED(CONFIG_IPV6)
if (sk->sk_family == AF_INET6)
tb->v6_rcv_saddr = sk->sk_v6_rcv_saddr;
else
#endif
tb->rcv_saddr = sk->sk_rcv_saddr;
INIT_HLIST_HEAD(&tb->owners);
hlist_add_head(&tb->node, &head->chain);
}
struct inet_bind2_bucket *inet_bind2_bucket_create(struct kmem_cache *cachep,
struct net *net,
struct inet_bind_hashbucket *head,
unsigned short port,
int l3mdev,
const struct sock *sk)
{
struct inet_bind2_bucket *tb = kmem_cache_alloc(cachep, GFP_ATOMIC);
if (tb)
inet_bind2_bucket_init(tb, net, head, port, l3mdev, sk);
return tb;
}
/* 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)
{
if (hlist_empty(&tb->owners)) {
__hlist_del(&tb->node);
kmem_cache_free(cachep, tb);
}
}
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);
#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)
{
inet_sk(sk)->inet_num = port;
sk_add_bind_node(sk, &tb->owners);
inet_csk(sk)->icsk_bind_hash = tb;
sk_add_bind2_node(sk, &tb2->owners);
inet_csk(sk)->icsk_bind2_hash = tb2;
}
/*
* 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 = sk->sk_prot->h.hashinfo;
const int bhash = inet_bhashfn(sock_net(sk), inet_sk(sk)->inet_num,
hashinfo->bhash_size);
struct inet_bind_hashbucket *head = &hashinfo->bhash[bhash];
struct inet_bind_hashbucket *head2 =
inet_bhashfn_portaddr(hashinfo, sk, sock_net(sk),
inet_sk(sk)->inet_num);
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)->inet_num = 0;
inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
spin_lock(&head2->lock);
if (inet_csk(sk)->icsk_bind2_hash) {
struct inet_bind2_bucket *tb2 = inet_csk(sk)->icsk_bind2_hash;
__sk_del_bind2_node(sk);
inet_csk(sk)->icsk_bind2_hash = NULL;
inet_bind2_bucket_destroy(hashinfo->bind2_bucket_cachep, tb2);
}
spin_unlock(&head2->lock);
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 = sk->sk_prot->h.hashinfo;
unsigned short port = inet_sk(child)->inet_num;
const int bhash = inet_bhashfn(sock_net(sk), port,
table->bhash_size);
struct inet_bind_hashbucket *head = &table->bhash[bhash];
struct inet_bind_hashbucket *head2 =
inet_bhashfn_portaddr(table, child, sock_net(sk), port);
bool created_inet_bind_bucket = false;
bool update_fastreuse = false;
struct net *net = sock_net(sk);
struct inet_bind2_bucket *tb2;
struct inet_bind_bucket *tb;
int l3mdev;
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, port,
l3mdev, child);
if (!tb2)
goto error;
}
}
if (update_fastreuse)
inet_csk_update_fastreuse(tb, child);
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(table->bind_bucket_cachep, 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, 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) && 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;
}
static inline struct sock *lookup_reuseport(struct net *net, struct sock *sk,
struct sk_buff *skb, int doff,
__be32 saddr, __be16 sport,
__be32 daddr, unsigned short hnum)
{
struct sock *reuse_sk = NULL;
u32 phash;
if (sk->sk_reuseport) {
phash = inet_ehashfn(net, daddr, hnum, saddr, sport);
reuse_sk = reuseport_select_sock(sk, phash, skb, doff);
}
return reuse_sk;
}
/*
* 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(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 = lookup_reuseport(net, sk, skb, doff,
saddr, sport, daddr, hnum);
if (result)
return result;
result = sk;
hiscore = score;
}
}
return result;
}
static inline struct sock *inet_lookup_run_bpf(struct net *net,
struct inet_hashinfo *hashinfo,
struct sk_buff *skb, int doff,
__be32 saddr, __be16 sport,
__be32 daddr, u16 hnum, const int dif)
{
struct sock *sk, *reuse_sk;
bool no_reuseport;
if (hashinfo != &tcp_hashinfo)
return NULL; /* only TCP is supported */
no_reuseport = bpf_sk_lookup_run_v4(net, IPPROTO_TCP, saddr, sport,
daddr, hnum, dif, &sk);
if (no_reuseport || IS_ERR_OR_NULL(sk))
return sk;
reuse_sk = lookup_reuseport(net, sk, skb, doff, saddr, sport, daddr, hnum);
if (reuse_sk)
sk = reuse_sk;
return sk;
}
struct sock *__inet_lookup_listener(struct net *net,
struct inet_hashinfo *hashinfo,
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 sock *result = NULL;
unsigned int hash2;
/* Lookup redirect from BPF */
if (static_branch_unlikely(&bpf_sk_lookup_enabled)) {
result = inet_lookup_run_bpf(net, hashinfo, skb, doff,
saddr, sport, daddr, hnum, dif);
if (result)
goto done;
}
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(struct net *net,
struct inet_hashinfo *hashinfo,
const __be32 saddr, const __be16 sport,
const __be32 daddr, const u16 hnum,
const int dif, const int sdif)
{
INET_ADDR_COOKIE(acookie, saddr, daddr);
const __portpair ports = INET_COMBINED_PORTS(sport, hnum);
struct sock *sk;
const struct hlist_nulls_node *node;
/* Optimize here for direct hit, only listening connections can
* have wildcards anyways.
*/
unsigned int hash = inet_ehashfn(net, daddr, hnum, saddr, sport);
unsigned int slot = hash & hashinfo->ehash_mask;
struct inet_ehash_bucket *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)
{
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);
unsigned int hash = inet_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 = NULL;
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 (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 = sk->sk_prot->h.hashinfo;
struct hlist_nulls_head *list;
struct inet_ehash_bucket *head;
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_del_node_init_rcu(osk);
} else 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);
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 {
this_cpu_inc(*sk->sk_prot->orphan_count);
inet_sk_set_state(sk, TCP_CLOSE);
sock_set_flag(sk, SOCK_DEAD);
inet_csk_destroy_sock(sk);
}
return ok;
}
EXPORT_SYMBOL_GPL(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;
struct sock *sk2;
kuid_t uid = sock_i_uid(sk);
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, sock_i_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 sock *osk)
{
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
struct inet_listen_hashbucket *ilb2;
int err = 0;
if (sk->sk_state != TCP_LISTEN) {
local_bh_disable();
inet_ehash_nolisten(sk, osk, 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;
}
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_set_flag(sk, SOCK_RCU_FREE);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
unlock:
spin_unlock(&ilb2->lock);
return err;
}
EXPORT_SYMBOL(__inet_hash);
int inet_hash(struct sock *sk)
{
int err = 0;
if (sk->sk_state != TCP_CLOSE)
err = __inet_hash(sk, NULL);
return err;
}
EXPORT_SYMBOL_GPL(inet_hash);
void inet_unhash(struct sock *sk)
{
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
if (sk_unhashed(sk))
return;
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 (sk_unhashed(sk)) {
spin_unlock(&ilb2->lock);
return;
}
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);
if (sk_unhashed(sk)) {
spin_unlock_bh(lock);
return;
}
__sk_nulls_del_node_init_rcu(sk);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
spin_unlock_bh(lock);
}
}
EXPORT_SYMBOL_GPL(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 IS_ENABLED(CONFIG_IPV6)
if (sk->sk_family == AF_INET6)
return net_eq(ib2_net(tb), net) && tb->port == port &&
tb->l3mdev == l3mdev &&
ipv6_addr_equal(&tb->v6_rcv_saddr, &sk->sk_v6_rcv_saddr);
else
#endif
return net_eq(ib2_net(tb), net) && tb->port == port &&
tb->l3mdev == l3mdev && tb->rcv_saddr == sk->sk_rcv_saddr;
}
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 IS_ENABLED(CONFIG_IPV6)
struct in6_addr addr_any = {};
if (sk->sk_family == AF_INET6)
return net_eq(ib2_net(tb), net) && tb->port == port &&
tb->l3mdev == l3mdev &&
ipv6_addr_equal(&tb->v6_rcv_saddr, &addr_any);
else
#endif
return net_eq(ib2_net(tb), net) && tb->port == port &&
tb->l3mdev == l3mdev && 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 = sk->sk_prot->h.hashinfo;
u32 hash;
#if IS_ENABLED(CONFIG_IPV6)
struct in6_addr addr_any = {};
if (sk->sk_family == AF_INET6)
hash = ipv6_portaddr_hash(net, &addr_any, port);
else
#endif
hash = ipv4_portaddr_hash(net, 0, port);
return &hinfo->bhash2[hash & (hinfo->bhash_size - 1)];
}
int inet_bhash2_update_saddr(struct inet_bind_hashbucket *prev_saddr, struct sock *sk)
{
struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
struct inet_bind2_bucket *tb2, *new_tb2;
int l3mdev = inet_sk_bound_l3mdev(sk);
struct inet_bind_hashbucket *head2;
int port = inet_sk(sk)->inet_num;
struct net *net = sock_net(sk);
/* 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)
return -ENOMEM;
head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
if (prev_saddr) {
spin_lock_bh(&prev_saddr->lock);
__sk_del_bind2_node(sk);
inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep,
inet_csk(sk)->icsk_bind2_hash);
spin_unlock_bh(&prev_saddr->lock);
}
spin_lock_bh(&head2->lock);
tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
if (!tb2) {
tb2 = new_tb2;
inet_bind2_bucket_init(tb2, net, head2, port, l3mdev, sk);
}
sk_add_bind2_node(sk, &tb2->owners);
inet_csk(sk)->icsk_bind2_hash = tb2;
spin_unlock_bh(&head2->lock);
if (tb2 != new_tb2)
kmem_cache_free(hinfo->bind2_bucket_cachep, new_tb2);
return 0;
}
EXPORT_SYMBOL_GPL(inet_bhash2_update_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 instead to really
* give more isolation and privacy, at the expense of 256kB of kernel
* memory.
*/
#define INET_TABLE_PERTURB_SHIFT 16
#define INET_TABLE_PERTURB_SIZE (1 << INET_TABLE_PERTURB_SHIFT)
static u32 *table_perturb;
int __inet_hash_connect(struct inet_timewait_death_row *death_row,
struct sock *sk, u64 port_offset,
int (*check_established)(struct inet_timewait_death_row *,
struct sock *, __u16, struct inet_timewait_sock **))
{
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;
int l3mdev;
u32 index;
if (port) {
head = &hinfo->bhash[inet_bhashfn(net, port,
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_ehash_nolisten(sk, NULL, NULL);
spin_unlock_bh(&head->lock);
return 0;
}
spin_unlock(&head->lock);
/* No definite answer... Walk to established hash table */
ret = check_established(death_row, sk, port, NULL);
local_bh_enable();
return ret;
}
l3mdev = inet_sk_bound_l3mdev(sk);
inet_get_local_port_range(net, &low, &high);
high++; /* [32768, 60999] -> [32768, 61000[ */
remaining = high - low;
if (likely(remaining > 1))
remaining &= ~1U;
net_get_random_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.
*/
offset &= ~1U;
other_parity_scan:
port = low + offset;
for (i = 0; i < remaining; i += 2, port += 2) {
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)];
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;
WARN_ON(hlist_empty(&tb->owners));
if (!check_established(death_row, sk,
port, &tw))
goto ok;
goto next_port;
}
}
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:
spin_unlock_bh(&head->lock);
cond_resched();
}
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, port, l3mdev, sk);
if (!tb2)
goto error;
}
/* 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, (prandom_u32() & 7) * 2);
WRITE_ONCE(table_perturb[index], READ_ONCE(table_perturb[index]) + i + 2);
/* Head lock still held and bh's disabled */
inet_bind_hash(sk, tb, tb2, port);
spin_unlock(&head2->lock);
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(&head->lock);
if (tw)
inet_twsk_deschedule_put(tw);
local_bh_enable();
return 0;
error:
spin_unlock(&head2->lock);
if (tb_created)
inet_bind_bucket_destroy(hinfo->bind_bucket_cachep, tb);
spin_unlock_bh(&head->lock);
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)
{
u64 port_offset = 0;
if (!inet_sk(sk)->inet_num)
port_offset = inet_sk_port_offset(sk);
return __inet_hash_connect(death_row, sk, port_offset,
__inet_check_established);
}
EXPORT_SYMBOL_GPL(inet_hash_connect);
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_array(INET_LHTABLE_SIZE, sizeof(*h->lhash2), GFP_KERNEL);
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;
}
EXPORT_SYMBOL_GPL(inet_hashinfo2_init_mod);
int inet_ehash_locks_alloc(struct inet_hashinfo *hashinfo)
{
unsigned int locksz = sizeof(spinlock_t);
unsigned int i, nblocks = 1;
if (locksz != 0) {
/* allocate 2 cache lines or at least one spinlock per cpu */
nblocks = max(2U * L1_CACHE_BYTES / locksz, 1U);
nblocks = roundup_pow_of_two(nblocks * num_possible_cpus());
/* no more locks than number of hash buckets */
nblocks = min(nblocks, hashinfo->ehash_mask + 1);
hashinfo->ehash_locks = kvmalloc_array(nblocks, locksz, GFP_KERNEL);
if (!hashinfo->ehash_locks)
return -ENOMEM;
for (i = 0; i < nblocks; i++)
spin_lock_init(&hashinfo->ehash_locks[i]);
}
hashinfo->ehash_locks_mask = nblocks - 1;
return 0;
}
EXPORT_SYMBOL_GPL(inet_ehash_locks_alloc);
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