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);