/* * 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. * * Authors: Lotsa people, from code originally in tcp * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #ifndef _INET_HASHTABLES_H #define _INET_HASHTABLES_H #include <linux/config.h> #include <linux/interrupt.h> #include <linux/ipv6.h> #include <linux/list.h> #include <linux/slab.h> #include <linux/socket.h> #include <linux/spinlock.h> #include <linux/types.h> #include <linux/wait.h> #include <net/inet_connection_sock.h> #include <net/route.h> #include <net/sock.h> #include <net/tcp_states.h> #include <asm/atomic.h> #include <asm/byteorder.h> /* This is for all connections with a full identity, no wildcards. * New scheme, half the table is for TIME_WAIT, the other half is * for the rest. I'll experiment with dynamic table growth later. */ struct inet_ehash_bucket { rwlock_t lock; struct hlist_head chain; } __attribute__((__aligned__(8))); /* There are a few simple rules, which allow for local port reuse by * an application. In essence: * * 1) Sockets bound to different interfaces may share a local port. * Failing that, goto test 2. * 2) If all sockets have sk->sk_reuse set, and none of them are in * TCP_LISTEN state, the port may be shared. * Failing that, goto test 3. * 3) If all sockets are bound to a specific inet_sk(sk)->rcv_saddr local * address, and none of them are the same, the port may be * shared. * Failing this, the port cannot be shared. * * The interesting point, is test #2. This is what an FTP server does * all day. To optimize this case we use a specific flag bit defined * below. As we add sockets to a bind bucket list, we perform a * check of: (newsk->sk_reuse && (newsk->sk_state != TCP_LISTEN)) * As long as all sockets added to a bind bucket pass this test, * the flag bit will be set. * The resulting situation is that tcp_v[46]_verify_bind() can just check * for this flag bit, if it is set and the socket trying to bind has * sk->sk_reuse set, we don't even have to walk the owners list at all, * we return that it is ok to bind this socket to the requested local port. * * Sounds like a lot of work, but it is worth it. In a more naive * implementation (ie. current FreeBSD etc.) the entire list of ports * must be walked for each data port opened by an ftp server. Needless * to say, this does not scale at all. With a couple thousand FTP * users logged onto your box, isn't it nice to know that new data * ports are created in O(1) time? I thought so. ;-) -DaveM */ struct inet_bind_bucket { unsigned short port; signed short fastreuse; struct hlist_node node; struct hlist_head owners; }; #define inet_bind_bucket_for_each(tb, node, head) \ hlist_for_each_entry(tb, node, head, node) struct inet_bind_hashbucket { spinlock_t lock; struct hlist_head chain; }; /* This is for listening sockets, thus all sockets which possess wildcards. */ #define INET_LHTABLE_SIZE 32 /* Yes, really, this is all you need. */ struct inet_hashinfo { /* This is for sockets with full identity only. Sockets here will * always be without wildcards and will have the following invariant: * * TCP_ESTABLISHED <= sk->sk_state < TCP_CLOSE * * First half of the table is for sockets not in TIME_WAIT, second half * is for TIME_WAIT sockets only. */ struct inet_ehash_bucket *ehash; /* Ok, let's try this, I give up, we do need a local binding * TCP hash as well as the others for fast bind/connect. */ struct inet_bind_hashbucket *bhash; int bhash_size; int ehash_size; /* All sockets in TCP_LISTEN state will be in here. This is the only * table where wildcard'd TCP sockets can exist. Hash function here * is just local port number. */ struct hlist_head listening_hash[INET_LHTABLE_SIZE]; /* All the above members are written once at bootup and * never written again _or_ are predominantly read-access. * * Now align to a new cache line as all the following members * are often dirty. */ rwlock_t lhash_lock ____cacheline_aligned; atomic_t lhash_users; wait_queue_head_t lhash_wait; spinlock_t portalloc_lock; kmem_cache_t *bind_bucket_cachep; int port_rover; }; static inline int inet_ehashfn(const __u32 laddr, const __u16 lport, const __u32 faddr, const __u16 fport, const int ehash_size) { int h = (laddr ^ lport) ^ (faddr ^ fport); h ^= h >> 16; h ^= h >> 8; return h & (ehash_size - 1); } static inline int inet_sk_ehashfn(const struct sock *sk, const int ehash_size) { const struct inet_sock *inet = inet_sk(sk); const __u32 laddr = inet->rcv_saddr; const __u16 lport = inet->num; const __u32 faddr = inet->daddr; const __u16 fport = inet->dport; return inet_ehashfn(laddr, lport, faddr, fport, ehash_size); } extern struct inet_bind_bucket * inet_bind_bucket_create(kmem_cache_t *cachep, struct inet_bind_hashbucket *head, const unsigned short snum); extern void inet_bind_bucket_destroy(kmem_cache_t *cachep, struct inet_bind_bucket *tb); static inline int inet_bhashfn(const __u16 lport, const int bhash_size) { return lport & (bhash_size - 1); } extern void inet_bind_hash(struct sock *sk, struct inet_bind_bucket *tb, const unsigned short snum); /* These can have wildcards, don't try too hard. */ static inline int inet_lhashfn(const unsigned short num) { return num & (INET_LHTABLE_SIZE - 1); } static inline int inet_sk_listen_hashfn(const struct sock *sk) { return inet_lhashfn(inet_sk(sk)->num); } /* Caller must disable local BH processing. */ static inline void __inet_inherit_port(struct inet_hashinfo *table, struct sock *sk, struct sock *child) { const int bhash = inet_bhashfn(inet_sk(child)->num, table->bhash_size); struct inet_bind_hashbucket *head = &table->bhash[bhash]; struct inet_bind_bucket *tb; spin_lock(&head->lock); tb = inet_csk(sk)->icsk_bind_hash; sk_add_bind_node(child, &tb->owners); inet_csk(child)->icsk_bind_hash = tb; spin_unlock(&head->lock); } static inline void inet_inherit_port(struct inet_hashinfo *table, struct sock *sk, struct sock *child) { local_bh_disable(); __inet_inherit_port(table, sk, child); local_bh_enable(); } extern void inet_put_port(struct inet_hashinfo *table, struct sock *sk); extern void inet_listen_wlock(struct inet_hashinfo *hashinfo); /* * - We may sleep inside this lock. * - If sleeping is not required (or called from BH), * use plain read_(un)lock(&inet_hashinfo.lhash_lock). */ static inline void inet_listen_lock(struct inet_hashinfo *hashinfo) { /* read_lock synchronizes to candidates to writers */ read_lock(&hashinfo->lhash_lock); atomic_inc(&hashinfo->lhash_users); read_unlock(&hashinfo->lhash_lock); } static inline void inet_listen_unlock(struct inet_hashinfo *hashinfo) { if (atomic_dec_and_test(&hashinfo->lhash_users)) wake_up(&hashinfo->lhash_wait); } static inline void __inet_hash(struct inet_hashinfo *hashinfo, struct sock *sk, const int listen_possible) { struct hlist_head *list; rwlock_t *lock; BUG_TRAP(sk_unhashed(sk)); if (listen_possible && sk->sk_state == TCP_LISTEN) { list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)]; lock = &hashinfo->lhash_lock; inet_listen_wlock(hashinfo); } else { sk->sk_hashent = inet_sk_ehashfn(sk, hashinfo->ehash_size); list = &hashinfo->ehash[sk->sk_hashent].chain; lock = &hashinfo->ehash[sk->sk_hashent].lock; write_lock(lock); } __sk_add_node(sk, list); sock_prot_inc_use(sk->sk_prot); write_unlock(lock); if (listen_possible && sk->sk_state == TCP_LISTEN) wake_up(&hashinfo->lhash_wait); } static inline void inet_hash(struct inet_hashinfo *hashinfo, struct sock *sk) { if (sk->sk_state != TCP_CLOSE) { local_bh_disable(); __inet_hash(hashinfo, sk, 1); local_bh_enable(); } } static inline void inet_unhash(struct inet_hashinfo *hashinfo, struct sock *sk) { rwlock_t *lock; if (sk_unhashed(sk)) goto out; if (sk->sk_state == TCP_LISTEN) { local_bh_disable(); inet_listen_wlock(hashinfo); lock = &hashinfo->lhash_lock; } else { struct inet_ehash_bucket *head = &hashinfo->ehash[sk->sk_hashent]; lock = &head->lock; write_lock_bh(&head->lock); } if (__sk_del_node_init(sk)) sock_prot_dec_use(sk->sk_prot); write_unlock_bh(lock); out: if (sk->sk_state == TCP_LISTEN) wake_up(&hashinfo->lhash_wait); } static inline int inet_iif(const struct sk_buff *skb) { return ((struct rtable *)skb->dst)->rt_iif; } extern struct sock *__inet_lookup_listener(const struct hlist_head *head, const u32 daddr, const unsigned short hnum, const int dif); /* Optimize the common listener case. */ static inline struct sock * inet_lookup_listener(struct inet_hashinfo *hashinfo, const u32 daddr, const unsigned short hnum, const int dif) { struct sock *sk = NULL; const struct hlist_head *head; read_lock(&hashinfo->lhash_lock); head = &hashinfo->listening_hash[inet_lhashfn(hnum)]; if (!hlist_empty(head)) { const struct inet_sock *inet = inet_sk((sk = __sk_head(head))); if (inet->num == hnum && !sk->sk_node.next && (!inet->rcv_saddr || inet->rcv_saddr == daddr) && (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) && !sk->sk_bound_dev_if) goto sherry_cache; sk = __inet_lookup_listener(head, daddr, hnum, dif); } if (sk) { sherry_cache: sock_hold(sk); } read_unlock(&hashinfo->lhash_lock); return sk; } /* Socket demux engine toys. */ #ifdef __BIG_ENDIAN #define INET_COMBINED_PORTS(__sport, __dport) \ (((__u32)(__sport) << 16) | (__u32)(__dport)) #else /* __LITTLE_ENDIAN */ #define INET_COMBINED_PORTS(__sport, __dport) \ (((__u32)(__dport) << 16) | (__u32)(__sport)) #endif #if (BITS_PER_LONG == 64) #ifdef __BIG_ENDIAN #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ const __u64 __name = (((__u64)(__saddr)) << 32) | ((__u64)(__daddr)); #else /* __LITTLE_ENDIAN */ #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \ const __u64 __name = (((__u64)(__daddr)) << 32) | ((__u64)(__saddr)); #endif /* __BIG_ENDIAN */ #define INET_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\ (((*((__u64 *)&(inet_sk(__sk)->daddr))) == (__cookie)) && \ ((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports)) && \ (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) #define INET_TW_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif)\ (((*((__u64 *)&(inet_twsk(__sk)->tw_daddr))) == (__cookie)) && \ ((*((__u32 *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) #else /* 32-bit arch */ #define INET_ADDR_COOKIE(__name, __saddr, __daddr) #define INET_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif) \ ((inet_sk(__sk)->daddr == (__saddr)) && \ (inet_sk(__sk)->rcv_saddr == (__daddr)) && \ ((*((__u32 *)&(inet_sk(__sk)->dport))) == (__ports)) && \ (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) #define INET_TW_MATCH(__sk, __cookie, __saddr, __daddr, __ports, __dif) \ ((inet_twsk(__sk)->tw_daddr == (__saddr)) && \ (inet_twsk(__sk)->tw_rcv_saddr == (__daddr)) && \ ((*((__u32 *)&(inet_twsk(__sk)->tw_dport))) == (__ports)) && \ (!((__sk)->sk_bound_dev_if) || ((__sk)->sk_bound_dev_if == (__dif)))) #endif /* 64-bit arch */ /* * Sockets in TCP_CLOSE state are _always_ taken out of the hash, so we need * not check it for lookups anymore, thanks Alexey. -DaveM * * Local BH must be disabled here. */ static inline struct sock * __inet_lookup_established(struct inet_hashinfo *hashinfo, const u32 saddr, const u16 sport, const u32 daddr, const u16 hnum, const int dif) { INET_ADDR_COOKIE(acookie, saddr, daddr) const __u32 ports = INET_COMBINED_PORTS(sport, hnum); struct sock *sk; const struct hlist_node *node; /* Optimize here for direct hit, only listening connections can * have wildcards anyways. */ const int hash = inet_ehashfn(daddr, hnum, saddr, sport, hashinfo->ehash_size); struct inet_ehash_bucket *head = &hashinfo->ehash[hash]; read_lock(&head->lock); sk_for_each(sk, node, &head->chain) { if (INET_MATCH(sk, acookie, saddr, daddr, ports, dif)) goto hit; /* You sunk my battleship! */ } /* Must check for a TIME_WAIT'er before going to listener hash. */ sk_for_each(sk, node, &(head + hashinfo->ehash_size)->chain) { if (INET_TW_MATCH(sk, acookie, saddr, daddr, ports, dif)) goto hit; } sk = NULL; out: read_unlock(&head->lock); return sk; hit: sock_hold(sk); goto out; } static inline struct sock *__inet_lookup(struct inet_hashinfo *hashinfo, const u32 saddr, const u16 sport, const u32 daddr, const u16 hnum, const int dif) { struct sock *sk = __inet_lookup_established(hashinfo, saddr, sport, daddr, hnum, dif); return sk ? : inet_lookup_listener(hashinfo, daddr, hnum, dif); } static inline struct sock *inet_lookup(struct inet_hashinfo *hashinfo, const u32 saddr, const u16 sport, const u32 daddr, const u16 dport, const int dif) { struct sock *sk; local_bh_disable(); sk = __inet_lookup(hashinfo, saddr, sport, daddr, ntohs(dport), dif); local_bh_enable(); return sk; } #endif /* _INET_HASHTABLES_H */