// 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 INET6 transport hashtables
   *

   * Authors:	Lotsa people, from code originally in tcp, generalised here

   *		by Arnaldo Carvalho de Melo <acme@mandriva.com>

   */

  #include <linux/module.h>

  #include <linux/random.h>

  #include <net/addrconf.h>

  #include <net/inet_connection_sock.h>
  #include <net/inet_hashtables.h>
  #include <net/inet6_hashtables.h>

  #include <net/secure_seq.h>

  #include <net/ip.h>

  #include <net/sock_reuseport.h>

  extern struct inet_hashinfo tcp_hashinfo;

  u32 inet6_ehashfn(const struct net *net,
  		  const struct in6_addr *laddr, const u16 lport,
  		  const struct in6_addr *faddr, const __be16 fport)

  {

  	static u32 inet6_ehash_secret __read_mostly;
  	static u32 ipv6_hash_secret __read_mostly;
  
  	u32 lhash, fhash;
  
  	net_get_random_once(&inet6_ehash_secret, sizeof(inet6_ehash_secret));
  	net_get_random_once(&ipv6_hash_secret, sizeof(ipv6_hash_secret));
  
  	lhash = (__force u32)laddr->s6_addr32[3];
  	fhash = __ipv6_addr_jhash(faddr, ipv6_hash_secret);

  	return __inet6_ehashfn(lhash, lport, fhash, fport,

  			       inet6_ehash_secret + net_hash_mix(net));

  }

  /*
   * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
   * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
   *
   * The sockhash lock must be held as a reader here.
   */

  struct sock *__inet6_lookup_established(struct net *net,
  					struct inet_hashinfo *hashinfo,

  					   const struct in6_addr *saddr,

  					   const __be16 sport,

  					   const struct in6_addr *daddr,
  					   const u16 hnum,

  					   const int dif, const int sdif)

  {
  	struct sock *sk;

  	const struct hlist_nulls_node *node;

  	const __portpair ports = INET_COMBINED_PORTS(sport, hnum);

  	/* Optimize here for direct hit, only listening connections can
  	 * have wildcards anyways.
  	 */

  	unsigned int hash = inet6_ehashfn(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 (!INET6_MATCH(sk, net, saddr, daddr, ports, dif, sdif))

  			continue;

  		if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))

  			goto out;

  		if (unlikely(!INET6_MATCH(sk, net, saddr, daddr, ports, dif, sdif))) {

  			sock_gen_put(sk);
  			goto begin;

  		}

  		goto found;

  	}

  	if (get_nulls_value(node) != slot)
  		goto begin;

  out:

  	sk = NULL;
  found:

  	return sk;
  }
  EXPORT_SYMBOL(__inet6_lookup_established);

  static inline int compute_score(struct sock *sk, struct net *net,

  				const unsigned short hnum,
  				const struct in6_addr *daddr,

  				const int dif, const int sdif)

  {
  	int score = -1;

  	if (net_eq(sock_net(sk), net) && inet_sk(sk)->inet_num == hnum &&

  	    sk->sk_family == PF_INET6) {

  		if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr))
  			return -1;

  		if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif))

  			return -1;

  		score = 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,
  					    const struct in6_addr *saddr,
  					    __be16 sport,
  					    const struct in6_addr *daddr,
  					    unsigned short hnum)
  {
  	struct sock *reuse_sk = NULL;
  	u32 phash;
  
  	if (sk->sk_reuseport) {
  		phash = inet6_ehashfn(net, daddr, hnum, saddr, sport);
  		reuse_sk = reuseport_select_sock(sk, phash, skb, doff);
  	}
  	return reuse_sk;
  }

  /* called with rcu_read_lock() */

  static struct sock *inet6_lhash2_lookup(struct net *net,
  		struct inet_listen_hashbucket *ilb2,
  		struct sk_buff *skb, int doff,
  		const struct in6_addr *saddr,
  		const __be16 sport, const struct in6_addr *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 *inet6_lookup_run_bpf(struct net *net,
  						struct inet_hashinfo *hashinfo,
  						struct sk_buff *skb, int doff,
  						const struct in6_addr *saddr,
  						const __be16 sport,
  						const struct in6_addr *daddr,
  						const 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_v6(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 *inet6_lookup_listener(struct net *net,

  		struct inet_hashinfo *hashinfo,
  		struct sk_buff *skb, int doff,
  		const struct in6_addr *saddr,

  		const __be16 sport, const struct in6_addr *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 = inet6_lookup_run_bpf(net, hashinfo, skb, doff,
  					      saddr, sport, daddr, hnum);
  		if (result)
  			goto done;
  	}

  	hash2 = ipv6_portaddr_hash(net, daddr, hnum);
  	ilb2 = inet_lhash2_bucket(hashinfo, hash2);

  
  	result = inet6_lhash2_lookup(net, ilb2, skb, doff,
  				     saddr, sport, daddr, hnum,
  				     dif, sdif);
  	if (result)

  		goto done;

  
  	/* Lookup lhash2 with in6addr_any */

  	hash2 = ipv6_portaddr_hash(net, &in6addr_any, hnum);
  	ilb2 = inet_lhash2_bucket(hashinfo, hash2);

  	result = inet6_lhash2_lookup(net, ilb2, skb, doff,

  				     saddr, sport, &in6addr_any, hnum,

  				     dif, sdif);

  done:

  	if (IS_ERR(result))

  		return NULL;

  	return result;
  }

  EXPORT_SYMBOL_GPL(inet6_lookup_listener);

  struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,

  			  struct sk_buff *skb, int doff,

  			  const struct in6_addr *saddr, const __be16 sport,
  			  const struct in6_addr *daddr, const __be16 dport,

  			  const int dif)
  {
  	struct sock *sk;

  	bool refcounted;

  	sk = __inet6_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,

  			    ntohs(dport), dif, 0, &refcounted);

  	if (sk && !refcounted && !refcount_inc_not_zero(&sk->sk_refcnt))

  		sk = NULL;

  	return sk;
  }

  EXPORT_SYMBOL_GPL(inet6_lookup);

  
  static int __inet6_check_established(struct inet_timewait_death_row *death_row,
  				     struct sock *sk, const __u16 lport,
  				     struct inet_timewait_sock **twp)
  {
  	struct inet_hashinfo *hinfo = death_row->hashinfo;

  	struct inet_sock *inet = inet_sk(sk);

  	const struct in6_addr *daddr = &sk->sk_v6_rcv_saddr;
  	const struct in6_addr *saddr = &sk->sk_v6_daddr;

  	const int dif = sk->sk_bound_dev_if;

  	struct net *net = sock_net(sk);

  	const int sdif = l3mdev_master_ifindex_by_index(net, dif);
  	const __portpair ports = INET_COMBINED_PORTS(inet->inet_dport, lport);

  	const unsigned int hash = inet6_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(INET6_MATCH(sk2, net, 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 inet6_sk_port_offset(const struct sock *sk)

  {
  	const struct inet_sock *inet = inet_sk(sk);

  
  	return secure_ipv6_port_ephemeral(sk->sk_v6_rcv_saddr.s6_addr32,
  					  sk->sk_v6_daddr.s6_addr32,

  					  inet->inet_dport);

  }
  
  int inet6_hash_connect(struct inet_timewait_death_row *death_row,
  		       struct sock *sk)
  {

  	u32 port_offset = 0;
  
  	if (!inet_sk(sk)->inet_num)
  		port_offset = inet6_sk_port_offset(sk);
  	return __inet_hash_connect(death_row, sk, port_offset,

  				   __inet6_check_established);

  }

  EXPORT_SYMBOL_GPL(inet6_hash_connect);

  
  int inet6_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(inet6_hash);