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linux/net/ipv4/inet_hashtables.c
Kuniyuki Iwashima 333bb73f62 tcp: Keep TCP_CLOSE sockets in the reuseport group. 
When we close a listening socket, to migrate its connections to another
listener in the same reuseport group, we have to handle two kinds of child
sockets. One is that a listening socket has a reference to, and the other
is not.

The former is the TCP_ESTABLISHED/TCP_SYN_RECV sockets, and they are in the
accept queue of their listening socket. So we can pop them out and push
them into another listener's queue at close() or shutdown() syscalls. On
the other hand, the latter, the TCP_NEW_SYN_RECV socket is during the
three-way handshake and not in the accept queue. Thus, we cannot access
such sockets at close() or shutdown() syscalls. Accordingly, we have to
migrate immature sockets after their listening socket has been closed.

Currently, if their listening socket has been closed, TCP_NEW_SYN_RECV
sockets are freed at receiving the final ACK or retransmitting SYN+ACKs. At
that time, if we could select a new listener from the same reuseport group,
no connection would be aborted. However, we cannot do that because
reuseport_detach_sock() sets NULL to sk_reuseport_cb and forbids access to
the reuseport group from closed sockets.

This patch allows TCP_CLOSE sockets to remain in the reuseport group and
access it while any child socket references them. The point is that
reuseport_detach_sock() was called twice from inet_unhash() and
sk_destruct(). This patch replaces the first reuseport_detach_sock() with
reuseport_stop_listen_sock(), which checks if the reuseport group is
capable of migration. If capable, it decrements num_socks, moves the socket
backwards in socks[] and increments num_closed_socks. When all connections
are migrated, sk_destruct() calls reuseport_detach_sock() to remove the
socket from socks[], decrement num_closed_socks, and set NULL to
sk_reuseport_cb.

By this change, closed or shutdowned sockets can keep sk_reuseport_cb.
Consequently, calling listen() after shutdown() can cause EADDRINUSE or
EBUSY in inet_csk_bind_conflict() or reuseport_add_sock() which expects
such sockets not to have the reuseport group. Therefore, this patch also
loosens such validation rules so that a socket can listen again if it has a
reuseport group with num_closed_socks more than 0.

When such sockets listen again, we handle them in reuseport_resurrect(). If
there is an existing reuseport group (reuseport_add_sock() path), we move
the socket from the old group to the new one and free the old one if
necessary. If there is no existing group (reuseport_alloc() path), we
allocate a new reuseport group, detach sk from the old one, and free it if
necessary, not to break the current shutdown behaviour:

  - we cannot carry over the eBPF prog of shutdowned sockets
  - we cannot attach/detach an eBPF prog to/from listening sockets via
    shutdowned sockets

Note that when the number of sockets gets over U16_MAX, we try to detach a
closed socket randomly to make room for the new listening socket in
reuseport_grow().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/bpf/20210612123224.12525-4-kuniyu@amazon.co.jp
2021-06-15 18:01:05 +02:00

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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);
}
}
void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb,
const unsigned short snum)
{
inet_sk(sk)->inet_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 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_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_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_bucket *tb;
int l3mdev;
spin_lock(&head->lock);
tb = inet_csk(sk)->icsk_bind_hash;
if (unlikely(!tb)) {
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 (net_eq(ib_net(tb), sock_net(sk)) &&
tb->l3mdev == l3mdev && tb->port == port)
break;
}
if (!tb) {
tb = inet_bind_bucket_create(table->bind_bucket_cachep,
sock_net(sk), head, port,
l3mdev);
if (!tb) {
spin_unlock(&head->lock);
return -ENOMEM;
}
}
inet_csk_update_fastreuse(tb, child);
}
inet_bind_hash(child, tb, port);
spin_unlock(&head->lock);
return 0;
}
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 void inet_hash2(struct inet_hashinfo *h, struct sock *sk)
{
struct inet_listen_hashbucket *ilb2;
if (!h->lhash2)
return;
ilb2 = inet_lhash2_bucket_sk(h, sk);
spin_lock(&ilb2->lock);
if (sk->sk_reuseport && sk->sk_family == AF_INET6)
hlist_add_tail_rcu(&inet_csk(sk)->icsk_listen_portaddr_node,
&ilb2->head);
else
hlist_add_head_rcu(&inet_csk(sk)->icsk_listen_portaddr_node,
&ilb2->head);
ilb2->count++;
spin_unlock(&ilb2->lock);
}
static void inet_unhash2(struct inet_hashinfo *h, struct sock *sk)
{
struct inet_listen_hashbucket *ilb2;
if (!h->lhash2 ||
WARN_ON_ONCE(hlist_unhashed(&inet_csk(sk)->icsk_listen_portaddr_node)))
return;
ilb2 = inet_lhash2_bucket_sk(h, sk);
spin_lock(&ilb2->lock);
hlist_del_init_rcu(&inet_csk(sk)->icsk_listen_portaddr_node);
ilb2->count--;
spin_unlock(&ilb2->lock);
}
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_family == PF_INET ? 2 : 1;
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 inet_connection_sock *icsk;
struct sock *sk, *result = NULL;
int score, hiscore = 0;
inet_lhash2_for_each_icsk_rcu(icsk, &ilb2->head) {
sk = (struct sock *)icsk;
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)
{
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, &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);
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(sk, net, acookie,
saddr, daddr, ports, dif, sdif))) {
if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
goto out;
if (unlikely(!INET_MATCH(sk, net, acookie,
saddr, daddr, 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(sk2, net, acookie,
saddr, daddr, 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 u32 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(esk, net, acookie,
sk->sk_daddr,
sk->sk_rcv_saddr,
ports, dif, sdif))) {
return true;
}
}
#if IS_ENABLED(CONFIG_IPV6)
else if (sk->sk_family == AF_INET6) {
if (unlikely(INET6_MATCH(esk, net,
&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 {
percpu_counter_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 *ilb;
int err = 0;
if (sk->sk_state != TCP_LISTEN) {
inet_ehash_nolisten(sk, osk, NULL);
return 0;
}
WARN_ON(!sk_unhashed(sk));
ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
spin_lock(&ilb->lock);
if (sk->sk_reuseport) {
err = inet_reuseport_add_sock(sk, ilb);
if (err)
goto unlock;
}
if (IS_ENABLED(CONFIG_IPV6) && sk->sk_reuseport &&
sk->sk_family == AF_INET6)
__sk_nulls_add_node_tail_rcu(sk, &ilb->nulls_head);
else
__sk_nulls_add_node_rcu(sk, &ilb->nulls_head);
inet_hash2(hashinfo, sk);
ilb->count++;
sock_set_flag(sk, SOCK_RCU_FREE);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
unlock:
spin_unlock(&ilb->lock);
return err;
}
EXPORT_SYMBOL(__inet_hash);
int inet_hash(struct sock *sk)
{
int err = 0;
if (sk->sk_state != TCP_CLOSE) {
local_bh_disable();
err = __inet_hash(sk, NULL);
local_bh_enable();
}
return err;
}
EXPORT_SYMBOL_GPL(inet_hash);
void inet_unhash(struct sock *sk)
{
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
struct inet_listen_hashbucket *ilb = NULL;
spinlock_t *lock;
if (sk_unhashed(sk))
return;
if (sk->sk_state == TCP_LISTEN) {
ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
lock = &ilb->lock;
} else {
lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
}
spin_lock_bh(lock);
if (sk_unhashed(sk))
goto unlock;
if (rcu_access_pointer(sk->sk_reuseport_cb))
reuseport_stop_listen_sock(sk);
if (ilb) {
inet_unhash2(hashinfo, sk);
ilb->count--;
}
__sk_nulls_del_node_init_rcu(sk);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
unlock:
spin_unlock_bh(lock);
}
EXPORT_SYMBOL_GPL(inet_unhash);
/* 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,
* we use 256 instead to really give more isolation and
* privacy, this only consumes 1 KB of kernel memory.
*/
#define INET_TABLE_PERTURB_SHIFT 8
static u32 table_perturb[1 << INET_TABLE_PERTURB_SHIFT];
int __inet_hash_connect(struct inet_timewait_death_row *death_row,
struct sock *sk, u32 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_timewait_sock *tw = NULL;
struct inet_bind_hashbucket *head;
int port = inet_sk(sk)->inet_num;
struct net *net = sock_net(sk);
struct inet_bind_bucket *tb;
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, sizeof(table_perturb));
index = hash_32(port_offset, INET_TABLE_PERTURB_SHIFT);
offset = (READ_ONCE(table_perturb[index]) + port_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 (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
tb->port == port) {
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->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:
/* If our first attempt found a candidate, skip next candidate
* in 1/16 of cases to add some noise.
*/
if (!i && !(prandom_u32() % 16))
i = 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, port);
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;
}
/*
* Bind a port for a connect operation and hash it.
*/
int inet_hash_connect(struct inet_timewait_death_row *death_row,
struct sock *sk)
{
u32 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);
void inet_hashinfo_init(struct inet_hashinfo *h)
{
int i;
for (i = 0; i < INET_LHTABLE_SIZE; i++) {
spin_lock_init(&h->listening_hash[i].lock);
INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].nulls_head,
i + LISTENING_NULLS_BASE);
h->listening_hash[i].count = 0;
}
h->lhash2 = NULL;
}
EXPORT_SYMBOL_GPL(inet_hashinfo_init);
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_HEAD(&h->lhash2[i].head);
h->lhash2[i].count = 0;
}
}
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);
}
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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