diff options
Diffstat (limited to 'kernel/net/ipv4/inet_timewait_sock.c')
| -rw-r--r-- | kernel/net/ipv4/inet_timewait_sock.c | 328 |
1 files changed, 328 insertions, 0 deletions
diff --git a/kernel/net/ipv4/inet_timewait_sock.c b/kernel/net/ipv4/inet_timewait_sock.c new file mode 100644 index 000000000..00ec8d5d7 --- /dev/null +++ b/kernel/net/ipv4/inet_timewait_sock.c @@ -0,0 +1,328 @@ +/* + * 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 TIME_WAIT sockets functions + * + * From code orinally in TCP + */ + +#include <linux/kernel.h> +#include <linux/kmemcheck.h> +#include <linux/slab.h> +#include <linux/module.h> +#include <net/inet_hashtables.h> +#include <net/inet_timewait_sock.h> +#include <net/ip.h> + + +/** + * inet_twsk_unhash - unhash a timewait socket from established hash + * @tw: timewait socket + * + * unhash a timewait socket from established hash, if hashed. + * ehash lock must be held by caller. + * Returns 1 if caller should call inet_twsk_put() after lock release. + */ +int inet_twsk_unhash(struct inet_timewait_sock *tw) +{ + if (hlist_nulls_unhashed(&tw->tw_node)) + return 0; + + hlist_nulls_del_rcu(&tw->tw_node); + sk_nulls_node_init(&tw->tw_node); + /* + * We cannot call inet_twsk_put() ourself under lock, + * caller must call it for us. + */ + return 1; +} + +/** + * inet_twsk_bind_unhash - unhash a timewait socket from bind hash + * @tw: timewait socket + * @hashinfo: hashinfo pointer + * + * unhash a timewait socket from bind hash, if hashed. + * bind hash lock must be held by caller. + * Returns 1 if caller should call inet_twsk_put() after lock release. + */ +int inet_twsk_bind_unhash(struct inet_timewait_sock *tw, + struct inet_hashinfo *hashinfo) +{ + struct inet_bind_bucket *tb = tw->tw_tb; + + if (!tb) + return 0; + + __hlist_del(&tw->tw_bind_node); + tw->tw_tb = NULL; + inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb); + /* + * We cannot call inet_twsk_put() ourself under lock, + * caller must call it for us. + */ + return 1; +} + +/* Must be called with locally disabled BHs. */ +static void inet_twsk_kill(struct inet_timewait_sock *tw) +{ + struct inet_hashinfo *hashinfo = tw->tw_dr->hashinfo; + struct inet_bind_hashbucket *bhead; + int refcnt; + /* Unlink from established hashes. */ + spinlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash); + + spin_lock(lock); + refcnt = inet_twsk_unhash(tw); + spin_unlock(lock); + + /* Disassociate with bind bucket. */ + bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), tw->tw_num, + hashinfo->bhash_size)]; + + spin_lock(&bhead->lock); + refcnt += inet_twsk_bind_unhash(tw, hashinfo); + spin_unlock(&bhead->lock); + + BUG_ON(refcnt >= atomic_read(&tw->tw_refcnt)); + atomic_sub(refcnt, &tw->tw_refcnt); + atomic_dec(&tw->tw_dr->tw_count); + inet_twsk_put(tw); +} + +void inet_twsk_free(struct inet_timewait_sock *tw) +{ + struct module *owner = tw->tw_prot->owner; + twsk_destructor((struct sock *)tw); +#ifdef SOCK_REFCNT_DEBUG + pr_debug("%s timewait_sock %p released\n", tw->tw_prot->name, tw); +#endif + kmem_cache_free(tw->tw_prot->twsk_prot->twsk_slab, tw); + module_put(owner); +} + +void inet_twsk_put(struct inet_timewait_sock *tw) +{ + if (atomic_dec_and_test(&tw->tw_refcnt)) + inet_twsk_free(tw); +} +EXPORT_SYMBOL_GPL(inet_twsk_put); + +static void inet_twsk_add_node_rcu(struct inet_timewait_sock *tw, + struct hlist_nulls_head *list) +{ + hlist_nulls_add_head_rcu(&tw->tw_node, list); +} + +static void inet_twsk_add_bind_node(struct inet_timewait_sock *tw, + struct hlist_head *list) +{ + hlist_add_head(&tw->tw_bind_node, list); +} + +/* + * Enter the time wait state. This is called with locally disabled BH. + * Essentially we whip up a timewait bucket, copy the relevant info into it + * from the SK, and mess with hash chains and list linkage. + */ +void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk, + struct inet_hashinfo *hashinfo) +{ + const struct inet_sock *inet = inet_sk(sk); + const struct inet_connection_sock *icsk = inet_csk(sk); + struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, sk->sk_hash); + spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash); + struct inet_bind_hashbucket *bhead; + /* Step 1: Put TW into bind hash. Original socket stays there too. + Note, that any socket with inet->num != 0 MUST be bound in + binding cache, even if it is closed. + */ + bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), inet->inet_num, + hashinfo->bhash_size)]; + spin_lock(&bhead->lock); + tw->tw_tb = icsk->icsk_bind_hash; + WARN_ON(!icsk->icsk_bind_hash); + inet_twsk_add_bind_node(tw, &tw->tw_tb->owners); + spin_unlock(&bhead->lock); + + spin_lock(lock); + + /* + * Step 2: Hash TW into tcp ehash chain. + * Notes : + * - tw_refcnt is set to 3 because : + * - We have one reference from bhash chain. + * - We have one reference from ehash chain. + * We can use atomic_set() because prior spin_lock()/spin_unlock() + * committed into memory all tw fields. + */ + atomic_set(&tw->tw_refcnt, 1 + 1 + 1); + inet_twsk_add_node_rcu(tw, &ehead->chain); + + /* Step 3: Remove SK from hash chain */ + if (__sk_nulls_del_node_init_rcu(sk)) + sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1); + + spin_unlock(lock); +} +EXPORT_SYMBOL_GPL(__inet_twsk_hashdance); + +void tw_timer_handler(unsigned long data) +{ + struct inet_timewait_sock *tw = (struct inet_timewait_sock *)data; + + if (tw->tw_kill) + NET_INC_STATS_BH(twsk_net(tw), LINUX_MIB_TIMEWAITKILLED); + else + NET_INC_STATS_BH(twsk_net(tw), LINUX_MIB_TIMEWAITED); + inet_twsk_kill(tw); +} + +struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, + struct inet_timewait_death_row *dr, + const int state) +{ + struct inet_timewait_sock *tw; + + if (atomic_read(&dr->tw_count) >= dr->sysctl_max_tw_buckets) + return NULL; + + tw = kmem_cache_alloc(sk->sk_prot_creator->twsk_prot->twsk_slab, + GFP_ATOMIC); + if (tw) { + const struct inet_sock *inet = inet_sk(sk); + + kmemcheck_annotate_bitfield(tw, flags); + + tw->tw_dr = dr; + /* Give us an identity. */ + tw->tw_daddr = inet->inet_daddr; + tw->tw_rcv_saddr = inet->inet_rcv_saddr; + tw->tw_bound_dev_if = sk->sk_bound_dev_if; + tw->tw_tos = inet->tos; + tw->tw_num = inet->inet_num; + tw->tw_state = TCP_TIME_WAIT; + tw->tw_substate = state; + tw->tw_sport = inet->inet_sport; + tw->tw_dport = inet->inet_dport; + tw->tw_family = sk->sk_family; + tw->tw_reuse = sk->sk_reuse; + tw->tw_hash = sk->sk_hash; + tw->tw_ipv6only = 0; + tw->tw_transparent = inet->transparent; + tw->tw_prot = sk->sk_prot_creator; + atomic64_set(&tw->tw_cookie, atomic64_read(&sk->sk_cookie)); + twsk_net_set(tw, sock_net(sk)); + setup_timer(&tw->tw_timer, tw_timer_handler, (unsigned long)tw); + /* + * Because we use RCU lookups, we should not set tw_refcnt + * to a non null value before everything is setup for this + * timewait socket. + */ + atomic_set(&tw->tw_refcnt, 0); + + __module_get(tw->tw_prot->owner); + } + + return tw; +} +EXPORT_SYMBOL_GPL(inet_twsk_alloc); + +/* These are always called from BH context. See callers in + * tcp_input.c to verify this. + */ + +/* This is for handling early-kills of TIME_WAIT sockets. */ +void inet_twsk_deschedule(struct inet_timewait_sock *tw) +{ + if (del_timer_sync(&tw->tw_timer)) + inet_twsk_kill(tw); +} +EXPORT_SYMBOL(inet_twsk_deschedule); + +void inet_twsk_schedule(struct inet_timewait_sock *tw, const int timeo) +{ + /* timeout := RTO * 3.5 + * + * 3.5 = 1+2+0.5 to wait for two retransmits. + * + * RATIONALE: if FIN arrived and we entered TIME-WAIT state, + * our ACK acking that FIN can be lost. If N subsequent retransmitted + * FINs (or previous seqments) are lost (probability of such event + * is p^(N+1), where p is probability to lose single packet and + * time to detect the loss is about RTO*(2^N - 1) with exponential + * backoff). Normal timewait length is calculated so, that we + * waited at least for one retransmitted FIN (maximal RTO is 120sec). + * [ BTW Linux. following BSD, violates this requirement waiting + * only for 60sec, we should wait at least for 240 secs. + * Well, 240 consumes too much of resources 8) + * ] + * This interval is not reduced to catch old duplicate and + * responces to our wandering segments living for two MSLs. + * However, if we use PAWS to detect + * old duplicates, we can reduce the interval to bounds required + * by RTO, rather than MSL. So, if peer understands PAWS, we + * kill tw bucket after 3.5*RTO (it is important that this number + * is greater than TS tick!) and detect old duplicates with help + * of PAWS. + */ + + tw->tw_kill = timeo <= 4*HZ; + if (!mod_timer_pinned(&tw->tw_timer, jiffies + timeo)) { + atomic_inc(&tw->tw_refcnt); + atomic_inc(&tw->tw_dr->tw_count); + } +} +EXPORT_SYMBOL_GPL(inet_twsk_schedule); + +void inet_twsk_purge(struct inet_hashinfo *hashinfo, + struct inet_timewait_death_row *twdr, int family) +{ + struct inet_timewait_sock *tw; + struct sock *sk; + struct hlist_nulls_node *node; + unsigned int slot; + + for (slot = 0; slot <= hashinfo->ehash_mask; slot++) { + struct inet_ehash_bucket *head = &hashinfo->ehash[slot]; +restart_rcu: + cond_resched(); + rcu_read_lock(); +restart: + sk_nulls_for_each_rcu(sk, node, &head->chain) { + if (sk->sk_state != TCP_TIME_WAIT) + continue; + tw = inet_twsk(sk); + if ((tw->tw_family != family) || + atomic_read(&twsk_net(tw)->count)) + continue; + + if (unlikely(!atomic_inc_not_zero(&tw->tw_refcnt))) + continue; + + if (unlikely((tw->tw_family != family) || + atomic_read(&twsk_net(tw)->count))) { + inet_twsk_put(tw); + goto restart; + } + + rcu_read_unlock(); + local_bh_disable(); + inet_twsk_deschedule(tw); + local_bh_enable(); + inet_twsk_put(tw); + goto restart_rcu; + } + /* 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 restart; + rcu_read_unlock(); + } +} +EXPORT_SYMBOL_GPL(inet_twsk_purge); |