1 files changed, 384 insertions, 0 deletions
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
new file mode 100644
index 000000000000..4d1502a49852
--- /dev/null
+++ b/net/ipv4/inet_timewait_sock.c
@@ -0,0 +1,384 @@
+/*
+ * 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/config.h>
+
+#include <net/inet_hashtables.h>
+#include <net/inet_timewait_sock.h>
+#include <net/ip.h>
+
+/* Must be called with locally disabled BHs. */
+void __inet_twsk_kill(struct inet_timewait_sock *tw, struct inet_hashinfo *hashinfo)
+{
+	struct inet_bind_hashbucket *bhead;
+	struct inet_bind_bucket *tb;
+	/* Unlink from established hashes. */
+	struct inet_ehash_bucket *ehead = &hashinfo->ehash[tw->tw_hashent];
+
+	write_lock(&ehead->lock);
+	if (hlist_unhashed(&tw->tw_node)) {
+		write_unlock(&ehead->lock);
+		return;
+	}
+	__hlist_del(&tw->tw_node);
+	sk_node_init(&tw->tw_node);
+	write_unlock(&ehead->lock);
+
+	/* Disassociate with bind bucket. */
+	bhead = &hashinfo->bhash[inet_bhashfn(tw->tw_num, hashinfo->bhash_size)];
+	spin_lock(&bhead->lock);
+	tb = tw->tw_tb;
+	__hlist_del(&tw->tw_bind_node);
+	tw->tw_tb = NULL;
+	inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
+	spin_unlock(&bhead->lock);
+#ifdef SOCK_REFCNT_DEBUG
+	if (atomic_read(&tw->tw_refcnt) != 1) {
+		printk(KERN_DEBUG "%s timewait_sock %p refcnt=%d\n",
+		       tw->tw_prot->name, tw, atomic_read(&tw->tw_refcnt));
+	}
+#endif
+	inet_twsk_put(tw);
+}
+
+EXPORT_SYMBOL_GPL(__inet_twsk_kill);
+
+/*
+ * 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 = &hashinfo->ehash[sk->sk_hashent];
+	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(inet->num, hashinfo->bhash_size)];
+	spin_lock(&bhead->lock);
+	tw->tw_tb = icsk->icsk_bind_hash;
+	BUG_TRAP(icsk->icsk_bind_hash);
+	inet_twsk_add_bind_node(tw, &tw->tw_tb->owners);
+	spin_unlock(&bhead->lock);
+
+	write_lock(&ehead->lock);
+
+	/* Step 2: Remove SK from established hash. */
+	if (__sk_del_node_init(sk))
+		sock_prot_dec_use(sk->sk_prot);
+
+	/* Step 3: Hash TW into TIMEWAIT half of established hash table. */
+	inet_twsk_add_node(tw, &(ehead + hashinfo->ehash_size)->chain);
+	atomic_inc(&tw->tw_refcnt);
+
+	write_unlock(&ehead->lock);
+}
+
+EXPORT_SYMBOL_GPL(__inet_twsk_hashdance);
+
+struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int state)
+{
+	struct inet_timewait_sock *tw = kmem_cache_alloc(sk->sk_prot_creator->twsk_slab,
+							 SLAB_ATOMIC);
+	if (tw != NULL) {
+		const struct inet_sock *inet = inet_sk(sk);
+
+		/* Give us an identity. */
+		tw->tw_daddr	    = inet->daddr;
+		tw->tw_rcv_saddr    = inet->rcv_saddr;
+		tw->tw_bound_dev_if = sk->sk_bound_dev_if;
+		tw->tw_num	    = inet->num;
+		tw->tw_state	    = TCP_TIME_WAIT;
+		tw->tw_substate	    = state;
+		tw->tw_sport	    = inet->sport;
+		tw->tw_dport	    = inet->dport;
+		tw->tw_family	    = sk->sk_family;
+		tw->tw_reuse	    = sk->sk_reuse;
+		tw->tw_hashent	    = sk->sk_hashent;
+		tw->tw_ipv6only	    = 0;
+		tw->tw_prot	    = sk->sk_prot_creator;
+		atomic_set(&tw->tw_refcnt, 1);
+		inet_twsk_dead_node_init(tw);
+	}
+
+	return tw;
+}
+
+EXPORT_SYMBOL_GPL(inet_twsk_alloc);
+
+/* Returns non-zero if quota exceeded.  */
+static int inet_twdr_do_twkill_work(struct inet_timewait_death_row *twdr,
+				    const int slot)
+{
+	struct inet_timewait_sock *tw;
+	struct hlist_node *node;
+	unsigned int killed;
+	int ret;
+
+	/* NOTE: compare this to previous version where lock
+	 * was released after detaching chain. It was racy,
+	 * because tw buckets are scheduled in not serialized context
+	 * in 2.3 (with netfilter), and with softnet it is common, because
+	 * soft irqs are not sequenced.
+	 */
+	killed = 0;
+	ret = 0;
+rescan:
+	inet_twsk_for_each_inmate(tw, node, &twdr->cells[slot]) {
+		__inet_twsk_del_dead_node(tw);
+		spin_unlock(&twdr->death_lock);
+		__inet_twsk_kill(tw, twdr->hashinfo);
+		inet_twsk_put(tw);
+		killed++;
+		spin_lock(&twdr->death_lock);
+		if (killed > INET_TWDR_TWKILL_QUOTA) {
+			ret = 1;
+			break;
+		}
+
+		/* While we dropped twdr->death_lock, another cpu may have
+		 * killed off the next TW bucket in the list, therefore
+		 * do a fresh re-read of the hlist head node with the
+		 * lock reacquired.  We still use the hlist traversal
+		 * macro in order to get the prefetches.
+		 */
+		goto rescan;
+	}
+
+	twdr->tw_count -= killed;
+	NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITED, killed);
+
+	return ret;
+}
+
+void inet_twdr_hangman(unsigned long data)
+{
+	struct inet_timewait_death_row *twdr;
+	int unsigned need_timer;
+
+	twdr = (struct inet_timewait_death_row *)data;
+	spin_lock(&twdr->death_lock);
+
+	if (twdr->tw_count == 0)
+		goto out;
+
+	need_timer = 0;
+	if (inet_twdr_do_twkill_work(twdr, twdr->slot)) {
+		twdr->thread_slots |= (1 << twdr->slot);
+		mb();
+		schedule_work(&twdr->twkill_work);
+		need_timer = 1;
+	} else {
+		/* We purged the entire slot, anything left?  */
+		if (twdr->tw_count)
+			need_timer = 1;
+	}
+	twdr->slot = ((twdr->slot + 1) & (INET_TWDR_TWKILL_SLOTS - 1));
+	if (need_timer)
+		mod_timer(&twdr->tw_timer, jiffies + twdr->period);
+out:
+	spin_unlock(&twdr->death_lock);
+}
+
+EXPORT_SYMBOL_GPL(inet_twdr_hangman);
+
+extern void twkill_slots_invalid(void);
+
+void inet_twdr_twkill_work(void *data)
+{
+	struct inet_timewait_death_row *twdr = data;
+	int i;
+
+	if ((INET_TWDR_TWKILL_SLOTS - 1) > (sizeof(twdr->thread_slots) * 8))
+		twkill_slots_invalid();
+
+	while (twdr->thread_slots) {
+		spin_lock_bh(&twdr->death_lock);
+		for (i = 0; i < INET_TWDR_TWKILL_SLOTS; i++) {
+			if (!(twdr->thread_slots & (1 << i)))
+				continue;
+
+			while (inet_twdr_do_twkill_work(twdr, i) != 0) {
+				if (need_resched()) {
+					spin_unlock_bh(&twdr->death_lock);
+					schedule();
+					spin_lock_bh(&twdr->death_lock);
+				}
+			}
+
+			twdr->thread_slots &= ~(1 << i);
+		}
+		spin_unlock_bh(&twdr->death_lock);
+	}
+}
+
+EXPORT_SYMBOL_GPL(inet_twdr_twkill_work);
+
+/* 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,
+			  struct inet_timewait_death_row *twdr)
+{
+	spin_lock(&twdr->death_lock);
+	if (inet_twsk_del_dead_node(tw)) {
+		inet_twsk_put(tw);
+		if (--twdr->tw_count == 0)
+			del_timer(&twdr->tw_timer);
+	}
+	spin_unlock(&twdr->death_lock);
+	__inet_twsk_kill(tw, twdr->hashinfo);
+}
+
+EXPORT_SYMBOL(inet_twsk_deschedule);
+
+void inet_twsk_schedule(struct inet_timewait_sock *tw,
+		       struct inet_timewait_death_row *twdr,
+		       const int timeo, const int timewait_len)
+{
+	struct hlist_head *list;
+	int slot;
+
+	/* 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.
+	 */
+	slot = (timeo + (1 << INET_TWDR_RECYCLE_TICK) - 1) >> INET_TWDR_RECYCLE_TICK;
+
+	spin_lock(&twdr->death_lock);
+
+	/* Unlink it, if it was scheduled */
+	if (inet_twsk_del_dead_node(tw))
+		twdr->tw_count--;
+	else
+		atomic_inc(&tw->tw_refcnt);
+
+	if (slot >= INET_TWDR_RECYCLE_SLOTS) {
+		/* Schedule to slow timer */
+		if (timeo >= timewait_len) {
+			slot = INET_TWDR_TWKILL_SLOTS - 1;
+		} else {
+			slot = (timeo + twdr->period - 1) / twdr->period;
+			if (slot >= INET_TWDR_TWKILL_SLOTS)
+				slot = INET_TWDR_TWKILL_SLOTS - 1;
+		}
+		tw->tw_ttd = jiffies + timeo;
+		slot = (twdr->slot + slot) & (INET_TWDR_TWKILL_SLOTS - 1);
+		list = &twdr->cells[slot];
+	} else {
+		tw->tw_ttd = jiffies + (slot << INET_TWDR_RECYCLE_TICK);
+
+		if (twdr->twcal_hand < 0) {
+			twdr->twcal_hand = 0;
+			twdr->twcal_jiffie = jiffies;
+			twdr->twcal_timer.expires = twdr->twcal_jiffie +
+					      (slot << INET_TWDR_RECYCLE_TICK);
+			add_timer(&twdr->twcal_timer);
+		} else {
+			if (time_after(twdr->twcal_timer.expires,
+				       jiffies + (slot << INET_TWDR_RECYCLE_TICK)))
+				mod_timer(&twdr->twcal_timer,
+					  jiffies + (slot << INET_TWDR_RECYCLE_TICK));
+			slot = (twdr->twcal_hand + slot) & (INET_TWDR_RECYCLE_SLOTS - 1);
+		}
+		list = &twdr->twcal_row[slot];
+	}
+
+	hlist_add_head(&tw->tw_death_node, list);
+
+	if (twdr->tw_count++ == 0)
+		mod_timer(&twdr->tw_timer, jiffies + twdr->period);
+	spin_unlock(&twdr->death_lock);
+}
+
+EXPORT_SYMBOL_GPL(inet_twsk_schedule);
+
+void inet_twdr_twcal_tick(unsigned long data)
+{
+	struct inet_timewait_death_row *twdr;
+	int n, slot;
+	unsigned long j;
+	unsigned long now = jiffies;
+	int killed = 0;
+	int adv = 0;
+
+	twdr = (struct inet_timewait_death_row *)data;
+
+	spin_lock(&twdr->death_lock);
+	if (twdr->twcal_hand < 0)
+		goto out;
+
+	slot = twdr->twcal_hand;
+	j = twdr->twcal_jiffie;
+
+	for (n = 0; n < INET_TWDR_RECYCLE_SLOTS; n++) {
+		if (time_before_eq(j, now)) {
+			struct hlist_node *node, *safe;
+			struct inet_timewait_sock *tw;
+
+			inet_twsk_for_each_inmate_safe(tw, node, safe,
+						       &twdr->twcal_row[slot]) {
+				__inet_twsk_del_dead_node(tw);
+				__inet_twsk_kill(tw, twdr->hashinfo);
+				inet_twsk_put(tw);
+				killed++;
+			}
+		} else {
+			if (!adv) {
+				adv = 1;
+				twdr->twcal_jiffie = j;
+				twdr->twcal_hand = slot;
+			}
+
+			if (!hlist_empty(&twdr->twcal_row[slot])) {
+				mod_timer(&twdr->twcal_timer, j);
+				goto out;
+			}
+		}
+		j += 1 << INET_TWDR_RECYCLE_TICK;
+		slot = (slot + 1) & (INET_TWDR_RECYCLE_SLOTS - 1);
+	}
+	twdr->twcal_hand = -1;
+
+out:
+	if ((twdr->tw_count -= killed) == 0)
+		del_timer(&twdr->tw_timer);
+	NET_ADD_STATS_BH(LINUX_MIB_TIMEWAITKILLED, killed);
+	spin_unlock(&twdr->death_lock);
+}
+
+EXPORT_SYMBOL_GPL(inet_twdr_twcal_tick);