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linux-stable/net/ipv4/inet_hashtables.c
Jakub Sitnicki 91d0b78c51 inet: Add IP_LOCAL_PORT_RANGE socket option 
Users who want to share a single public IP address for outgoing connections
between several hosts traditionally reach for SNAT. However, SNAT requires
state keeping on the node(s) performing the NAT.

A stateless alternative exists, where a single IP address used for egress
can be shared between several hosts by partitioning the available ephemeral
port range. In such a setup:

1. Each host gets assigned a disjoint range of ephemeral ports.
2. Applications open connections from the host-assigned port range.
3. Return traffic gets routed to the host based on both, the destination IP
   and the destination port.

An application which wants to open an outgoing connection (connect) from a
given port range today can choose between two solutions:

1. Manually pick the source port by bind()'ing to it before connect()'ing
   the socket.

   This approach has a couple of downsides:

   a) Search for a free port has to be implemented in the user-space. If
      the chosen 4-tuple happens to be busy, the application needs to retry
      from a different local port number.

      Detecting if 4-tuple is busy can be either easy (TCP) or hard
      (UDP). In TCP case, the application simply has to check if connect()
      returned an error (EADDRNOTAVAIL). That is assuming that the local
      port sharing was enabled (REUSEADDR) by all the sockets.

        # Assume desired local port range is 60_000-60_511
        s = socket(AF_INET, SOCK_STREAM)
        s.setsockopt(SOL_SOCKET, SO_REUSEADDR, 1)
        s.bind(("192.0.2.1", 60_000))
        s.connect(("1.1.1.1", 53))
        # Fails only if 192.0.2.1:60000 -> 1.1.1.1:53 is busy
        # Application must retry with another local port

      In case of UDP, the network stack allows binding more than one socket
      to the same 4-tuple, when local port sharing is enabled
      (REUSEADDR). Hence detecting the conflict is much harder and involves
      querying sock_diag and toggling the REUSEADDR flag [1].

   b) For TCP, bind()-ing to a port within the ephemeral port range means
      that no connecting sockets, that is those which leave it to the
      network stack to find a free local port at connect() time, can use
      the this port.

      IOW, the bind hash bucket tb->fastreuse will be 0 or 1, and the port
      will be skipped during the free port search at connect() time.

2. Isolate the app in a dedicated netns and use the use the per-netns
   ip_local_port_range sysctl to adjust the ephemeral port range bounds.

   The per-netns setting affects all sockets, so this approach can be used
   only if:

   - there is just one egress IP address, or
   - the desired egress port range is the same for all egress IP addresses
     used by the application.

   For TCP, this approach avoids the downsides of (1). Free port search and
   4-tuple conflict detection is done by the network stack:

     system("sysctl -w net.ipv4.ip_local_port_range='60000 60511'")

     s = socket(AF_INET, SOCK_STREAM)
     s.setsockopt(SOL_IP, IP_BIND_ADDRESS_NO_PORT, 1)
     s.bind(("192.0.2.1", 0))
     s.connect(("1.1.1.1", 53))
     # Fails if all 4-tuples 192.0.2.1:60000-60511 -> 1.1.1.1:53 are busy

  For UDP this approach has limited applicability. Setting the
  IP_BIND_ADDRESS_NO_PORT socket option does not result in local source
  port being shared with other connected UDP sockets.

  Hence relying on the network stack to find a free source port, limits the
  number of outgoing UDP flows from a single IP address down to the number
  of available ephemeral ports.

To put it another way, partitioning the ephemeral port range between hosts
using the existing Linux networking API is cumbersome.

To address this use case, add a new socket option at the SOL_IP level,
named IP_LOCAL_PORT_RANGE. The new option can be used to clamp down the
ephemeral port range for each socket individually.

The option can be used only to narrow down the per-netns local port
range. If the per-socket range lies outside of the per-netns range, the
latter takes precedence.

UAPI-wise, the low and high range bounds are passed to the kernel as a pair
of u16 values in host byte order packed into a u32. This avoids pointer
passing.

  PORT_LO = 40_000
  PORT_HI = 40_511

  s = socket(AF_INET, SOCK_STREAM)
  v = struct.pack("I", PORT_HI << 16 | PORT_LO)
  s.setsockopt(SOL_IP, IP_LOCAL_PORT_RANGE, v)
  s.bind(("127.0.0.1", 0))
  s.getsockname()
  # Local address between ("127.0.0.1", 40_000) and ("127.0.0.1", 40_511),
  # if there is a free port. EADDRINUSE otherwise.

[1] https://github.com/cloudflare/cloudflare-blog/blob/232b432c1d57/2022-02-connectx/connectx.py#L116

Reviewed-by: Marek Majkowski <marek@cloudflare.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2023-01-25 22:45:00 -08:00

1269 lines
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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)
tb->family = sk->sk_family;
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);
INIT_HLIST_HEAD(&tb->deathrow);
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_empty(&tb->deathrow)) {
__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 != tb2->family)
return false;
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 = tcp_or_dccp_get_hashinfo(sk);
struct inet_bind_hashbucket *head, *head2;
struct net *net = sock_net(sk);
struct inet_bind_bucket *tb;
int bhash;
bhash = inet_bhashfn(net, inet_sk(sk)->inet_num, hashinfo->bhash_size);
head = &hashinfo->bhash[bhash];
head2 = inet_bhashfn_portaddr(hashinfo, sk, net, inet_sk(sk)->inet_num);
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 = tcp_or_dccp_get_hashinfo(sk);
unsigned short port = inet_sk(child)->inet_num;
struct inet_bind_hashbucket *head, *head2;
bool created_inet_bind_bucket = false;
struct net *net = sock_net(sk);
bool update_fastreuse = false;
struct inet_bind2_bucket *tb2;
struct inet_bind_bucket *tb;
int bhash, l3mdev;
bhash = inet_bhashfn(net, port, table->bhash_size);
head = &table->bhash[bhash];
head2 = inet_bhashfn_portaddr(table, child, net, port);
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 != net->ipv4.tcp_death_row.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 = tcp_or_dccp_get_hashinfo(sk);
struct inet_ehash_bucket *head;
struct hlist_nulls_head *list;
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_hashed(osk);
if (ret) {
/* Before deleting the node, we insert a new one to make
* sure that the look-up-sk process would not miss either
* of them and that at least one node would exist in ehash
* table all the time. Otherwise there's a tiny chance
* that lookup process could find nothing in ehash table.
*/
__sk_nulls_add_node_tail_rcu(sk, list);
sk_nulls_del_node_init_rcu(osk);
}
goto unlock;
}
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);
unlock:
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 = tcp_or_dccp_get_hashinfo(sk);
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 = tcp_or_dccp_get_hashinfo(sk);
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 != tb->family)
return false;
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 != tb->family)
return false;
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 = tcp_or_dccp_get_hashinfo(sk);
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)];
}
static void inet_update_saddr(struct sock *sk, void *saddr, int family)
{
if (family == AF_INET) {
inet_sk(sk)->inet_saddr = *(__be32 *)saddr;
sk_rcv_saddr_set(sk, inet_sk(sk)->inet_saddr);
}
#if IS_ENABLED(CONFIG_IPV6)
else {
sk->sk_v6_rcv_saddr = *(struct in6_addr *)saddr;
}
#endif
}
static int __inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family, bool reset)
{
struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
struct inet_bind_hashbucket *head, *head2;
struct inet_bind2_bucket *tb2, *new_tb2;
int l3mdev = inet_sk_bound_l3mdev(sk);
int port = inet_sk(sk)->inet_num;
struct net *net = sock_net(sk);
int bhash;
if (!inet_csk(sk)->icsk_bind2_hash) {
/* Not bind()ed before. */
if (reset)
inet_reset_saddr(sk);
else
inet_update_saddr(sk, saddr, family);
return 0;
}
/* 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) {
if (reset) {
/* The (INADDR_ANY, port) bucket might have already
* been freed, then we cannot fixup icsk_bind2_hash,
* so we give up and unlink sk from bhash/bhash2 not
* to leave inconsistency in bhash2.
*/
inet_put_port(sk);
inet_reset_saddr(sk);
}
return -ENOMEM;
}
bhash = inet_bhashfn(net, port, hinfo->bhash_size);
head = &hinfo->bhash[bhash];
head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
/* If we change saddr locklessly, another thread
* iterating over bhash might see corrupted address.
*/
spin_lock_bh(&head->lock);
spin_lock(&head2->lock);
__sk_del_bind2_node(sk);
inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep, inet_csk(sk)->icsk_bind2_hash);
spin_unlock(&head2->lock);
if (reset)
inet_reset_saddr(sk);
else
inet_update_saddr(sk, saddr, family);
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 = 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(&head2->lock);
spin_unlock_bh(&head->lock);
if (tb2 != new_tb2)
kmem_cache_free(hinfo->bind2_bucket_cachep, new_tb2);
return 0;
}
int inet_bhash2_update_saddr(struct sock *sk, void *saddr, int family)
{
return __inet_bhash2_update_saddr(sk, saddr, family, false);
}
EXPORT_SYMBOL_GPL(inet_bhash2_update_saddr);
void inet_bhash2_reset_saddr(struct sock *sk)
{
if (!(sk->sk_userlocks & SOCK_BINDADDR_LOCK))
__inet_bhash2_update_saddr(sk, NULL, 0, true);
}
EXPORT_SYMBOL_GPL(inet_bhash2_reset_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 by default instead
* to really give more isolation and privacy, at the expense of 256kB
* of kernel memory.
*/
#define INET_TABLE_PERTURB_SIZE (1 << CONFIG_INET_TABLE_PERTURB_ORDER)
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) {
local_bh_disable();
ret = check_established(death_row, sk, port, NULL);
local_bh_enable();
return ret;
}
l3mdev = inet_sk_bound_l3mdev(sk);
inet_sk_get_local_port_range(sk, &low, &high);
high++; /* [32768, 60999] -> [32768, 61000[ */
remaining = high - low;
if (likely(remaining > 1))
remaining &= ~1U;
get_random_sleepable_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, get_random_u32_below(8) * 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);
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(&head2->lock);
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);
struct inet_hashinfo *inet_pernet_hashinfo_alloc(struct inet_hashinfo *hashinfo,
unsigned int ehash_entries)
{
struct inet_hashinfo *new_hashinfo;
int i;
new_hashinfo = kmemdup(hashinfo, sizeof(*hashinfo), GFP_KERNEL);
if (!new_hashinfo)
goto err;
new_hashinfo->ehash = vmalloc_huge(ehash_entries * sizeof(struct inet_ehash_bucket),
GFP_KERNEL_ACCOUNT);
if (!new_hashinfo->ehash)
goto free_hashinfo;
new_hashinfo->ehash_mask = ehash_entries - 1;
if (inet_ehash_locks_alloc(new_hashinfo))
goto free_ehash;
for (i = 0; i < ehash_entries; i++)
INIT_HLIST_NULLS_HEAD(&new_hashinfo->ehash[i].chain, i);
new_hashinfo->pernet = true;
return new_hashinfo;
free_ehash:
vfree(new_hashinfo->ehash);
free_hashinfo:
kfree(new_hashinfo);
err:
return NULL;
}
EXPORT_SYMBOL_GPL(inet_pernet_hashinfo_alloc);
void inet_pernet_hashinfo_free(struct inet_hashinfo *hashinfo)
{
if (!hashinfo->pernet)
return;
inet_ehash_locks_free(hashinfo);
vfree(hashinfo->ehash);
kfree(hashinfo);
}
EXPORT_SYMBOL_GPL(inet_pernet_hashinfo_free);
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