/*
* 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.
*
* Support for INET connection oriented protocols.
*
* Authors: See the TCP sources
*
* 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.
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/jhash.h>
#include <net/inet_connection_sock.h>
#include <net/inet_hashtables.h>
#include <net/inet_timewait_sock.h>
#include <net/ip.h>
#include <net/route.h>
#include <net/tcp_states.h>
#include <net/xfrm.h>
#ifdef INET_CSK_DEBUG
const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
EXPORT_SYMBOL(inet_csk_timer_bug_msg);
#endif
/*
* This array holds the first and last local port number.
* For high-usage systems, use sysctl to change this to
* 32768-61000
*/
int sysctl_local_port_range[2] = { 1024, 4999 };
static inline int inet_csk_bind_conflict(struct sock *sk, struct inet_bind_bucket *tb)
{
const u32 sk_rcv_saddr = inet_rcv_saddr(sk);
struct sock *sk2;
struct hlist_node *node;
int reuse = sk->sk_reuse;
sk_for_each_bound(sk2, node, &tb->owners) {
if (sk != sk2 &&
!inet_v6_ipv6only(sk2) &&
(!sk->sk_bound_dev_if ||
!sk2->sk_bound_dev_if ||
sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
if (!reuse || !sk2->sk_reuse ||
sk2->sk_state == TCP_LISTEN) {
const u32 sk2_rcv_saddr = inet_rcv_saddr(sk2);
if (!sk2_rcv_saddr || !sk_rcv_saddr ||
sk2_rcv_saddr == sk_rcv_saddr)
break;
}
}
}
return node != NULL;
}
/* Obtain a reference to a local port for the given sock,
* if snum is zero it means select any available local port.
*/
int inet_csk_get_port(struct inet_hashinfo *hashinfo,
struct sock *sk, unsigned short snum)
{
struct inet_bind_hashbucket *head;
struct hlist_node *node;
struct inet_bind_bucket *tb;
int ret;
local_bh_disable();
if (!snum) {
int low = sysctl_local_port_range[0];
int high = sysctl_local_port_range[1];
int remaining = (high - low) + 1;
int rover;
spin_lock(&hashinfo->portalloc_lock);
if (hashinfo->port_rover < low)
rover = low;
else
rover = hashinfo->port_rover;
do {
rover++;
if (rover > high)
rover = low;
head = &hashinfo->bhash[inet_bhashfn(rover, hashinfo->bhash_size)];
spin_lock(&head->lock);
inet_bind_bucket_for_each(tb, node, &head->chain)
if (tb->port == rover)
goto next;
break;
next:
spin_unlock(&head->lock);
} while (--remaining > 0);
hashinfo->port_rover = rover;
spin_unlock(&hashinfo->portalloc_lock);
/* Exhausted local port range during search? It is not
* possible for us to be holding one of the bind hash
* locks if this test triggers, because if 'remaining'
* drops to zero, we broke out of the do/while loop at
* the top level, not from the 'break;' statement.
*/
ret = 1;
if (remaining <= 0)
goto fail;
/* OK, here is the one we will use. HEAD is
* non-NULL and we hold it's mutex.
*/
snum = rover;
} else {
head = &hashinfo->bhash[inet_bhashfn(snum, hashinfo->bhash_size)];
spin_lock(&head->lock);
inet_bind_bucket_for_each(tb, node, &head->chain)
if (tb->port == snum)
goto tb_found;
}
tb = NULL;
goto tb_not_found;
tb_found:
if (!hlist_empty(&tb->owners)) {
if (sk->sk_reuse > 1)
goto success;
if (tb->fastreuse > 0 &&
sk->sk_reuse && sk->sk_state != TCP_LISTEN) {
goto success;
} else {
ret = 1;
if (inet_csk_bind_conflict(sk, tb))
goto fail_unlock;
}
}
tb_not_found:
ret = 1;
if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep, head, snum)) == NULL)
goto fail_unlock;
if (hlist_empty(&tb->owners)) {
if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
tb->fastreuse = 1;
else
tb->fastreuse = 0;
} else if (tb->fastreuse &&
(!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
tb->fastreuse = 0;
success:
if (!inet_csk(sk)->icsk_bind_hash)
inet_bind_hash(sk, tb, snum);
BUG_TRAP(inet_csk(sk)->icsk_bind_hash == tb);
ret = 0;
fail_unlock:
spin_unlock(&head->lock);
fail:
local_bh_enable();
return ret;
}
EXPORT_SYMBOL_GPL(inet_csk_get_port);
/*
* Wait for an incoming connection, avoid race conditions. This must be called
* with the socket locked.
*/
static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
{
struct inet_connection_sock *icsk = inet_csk(sk);
DEFINE_WAIT(wait);
int err;
/*
* True wake-one mechanism for incoming connections: only
* one process gets woken up, not the 'whole herd'.
* Since we do not 'race & poll' for established sockets
* anymore, the common case will execute the loop only once.
*
* Subtle issue: "add_wait_queue_exclusive()" will be added
* after any current non-exclusive waiters, and we know that
* it will always _stay_ after any new non-exclusive waiters
* because all non-exclusive waiters are added at the
* beginning of the wait-queue. As such, it's ok to "drop"
* our exclusiveness temporarily when we get woken up without
* having to remove and re-insert us on the wait queue.
*/
for (;;) {
prepare_to_wait_exclusive(sk->sk_sleep, &wait,
TASK_INTERRUPTIBLE);
release_sock(sk);
if (reqsk_queue_empty(&icsk->icsk_accept_queue))
timeo = schedule_timeout(timeo);
lock_sock(sk);
err = 0;
if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
break;
err = -EINVAL;
if (sk->sk_state != TCP_LISTEN)
break;
err = sock_intr_errno(timeo);
if (signal_pending(current))
break;
err = -EAGAIN;
if (!timeo)
break;
}
finish_wait(sk->sk_sleep, &wait);
return err;
}
/*
* This will accept the next outstanding connection.
*/
struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct sock *newsk;
int error;
lock_sock(sk);
/* We need to make sure that this socket is listening,
* and that it has something pending.
*/
error = -EINVAL;
if (sk->sk_state != TCP_LISTEN)
goto out_err;
/* Find already established connection */
if (reqsk_queue_empty(&icsk->icsk_accept_queue)) {
long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
/* If this is a non blocking socket don't sleep */
error = -EAGAIN;
if (!timeo)
goto out_err;
error = inet_csk_wait_for_connect(sk, timeo);
if (error)
goto out_err;
}
newsk = reqsk_queue_get_child(&icsk->icsk_accept_queue, sk);
BUG_TRAP(newsk->sk_state != TCP_SYN_RECV);
out:
release_sock(sk);
return newsk;
out_err:
newsk = NULL;
*err = error;
goto out;
}
EXPORT_SYMBOL(inet_csk_accept);
/*
* Using different timers for retransmit, delayed acks and probes
* We may wish use just one timer maintaining a list of expire jiffies
* to optimize.
*/
void inet_csk_init_xmit_timers(struct sock *sk,
void (*retransmit_handler)(unsigned long),
void (*delack_handler)(unsigned long),
void (*keepalive_handler)(unsigned long))
{
struct inet_connection_sock *icsk = inet_csk(sk);
init_timer(&icsk->icsk_retransmit_timer);
init_timer(&icsk->icsk_delack_timer);
init_timer(&sk->sk_timer);
icsk->icsk_retransmit_timer.function = retransmit_handler;
icsk->icsk_delack_timer.function = delack_handler;
sk->sk_timer.function = keepalive_handler;
icsk->icsk_retransmit_timer.data =
icsk->icsk_delack_timer.data =
sk->sk_timer.data = (unsigned long)sk;
icsk->icsk_pending = icsk->icsk_ack.pending = 0;
}
EXPORT_SYMBOL(inet_csk_init_xmit_timers);
void inet_csk_clear_xmit_timers(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
sk_stop_timer(sk, &icsk->icsk_delack_timer);
sk_stop_timer(sk, &sk->sk_timer);
}
EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
void inet_csk_delete_keepalive_timer(struct sock *sk)
{
sk_stop_timer(sk, &sk->sk_timer);
}
EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
{
sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
}
EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
struct dst_entry* inet_csk_route_req(struct sock *sk,
const struct request_sock *req)
{
struct rtable *rt;
const struct inet_request_sock *ireq = inet_rsk(req);
struct ip_options *opt = inet_rsk(req)->opt;
struct flowi fl = { .oif = sk->sk_bound_dev_if,
.nl_u = { .ip4_u =
{ .daddr = ((opt && opt->srr) ?
opt->faddr :
ireq->rmt_addr),
.saddr = ireq->loc_addr,
.tos = RT_CONN_FLAGS(sk) } },
.proto = sk->sk_protocol,
.uli_u = { .ports =
{ .sport = inet_sk(sk)->sport,
.dport = ireq->rmt_port } } };
if (ip_route_output_flow(&rt, &fl, sk, 0)) {
IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
return NULL;
}
if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway) {
ip_rt_put(rt);
IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
return NULL;
}
return &rt->u.dst;
}
EXPORT_SYMBOL_GPL(inet_csk_route_req);
static inline u32 inet_synq_hash(const u32 raddr, const u16 rport,
const u32 rnd, const u16 synq_hsize)
{
return jhash_2words(raddr, (u32)rport, rnd) & (synq_hsize - 1);
}
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
#define AF_INET_FAMILY(fam) ((fam) == AF_INET)
#else
#define AF_INET_FAMILY(fam) 1
#endif
struct request_sock *inet_csk_search_req(const struct sock *sk,
struct request_sock ***prevp,
const __u16 rport, const __u32 raddr,
const __u32 laddr)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
struct request_sock *req, **prev;
for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
lopt->nr_table_entries)];
(req = *prev) != NULL;
prev = &req->dl_next) {
const struct inet_request_sock *ireq = inet_rsk(req);
if (ireq->rmt_port == rport &&
ireq->rmt_addr == raddr &&
ireq->loc_addr == laddr &&
AF_INET_FAMILY(req->rsk_ops->family)) {
BUG_TRAP(!req->sk);
*prevp = prev;
break;
}
}
return req;
}
EXPORT_SYMBOL_GPL(inet_csk_search_req);
void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
const unsigned timeout)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port,
lopt->hash_rnd, lopt->nr_table_entries);
reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
inet_csk_reqsk_queue_added(sk, timeout);
}
/* Only thing we need from tcp.h */
extern int sysctl_tcp_synack_retries;
EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
void inet_csk_reqsk_queue_prune(struct sock *parent,
const unsigned long interval,
const unsigned long timeout,
const unsigned long max_rto)
{
struct inet_connection_sock *icsk = inet_csk(parent);
struct request_sock_queue *queue = &icsk->icsk_accept_queue;
struct listen_sock *lopt = queue->listen_opt;
int max_retries = icsk->icsk_syn_retries ? : sysctl_tcp_synack_retries;
int thresh = max_retries;
unsigned long now = jiffies;
struct request_sock **reqp, *req;
int i, budget;
if (lopt == NULL || lopt->qlen == 0)
return;
/* Normally all the openreqs are young and become mature
* (i.e. converted to established socket) for first timeout.
* If synack was not acknowledged for 3 seconds, it means
* one of the following things: synack was lost, ack was lost,
* rtt is high or nobody planned to ack (i.e. synflood).
* When server is a bit loaded, queue is populated with old
* open requests, reducing effective size of queue.
* When server is well loaded, queue size reduces to zero
* after several minutes of work. It is not synflood,
* it is normal operation. The solution is pruning
* too old entries overriding normal timeout, when
* situation becomes dangerous.
*
* Essentially, we reserve half of room for young
* embrions; and abort old ones without pity, if old
* ones are about to clog our table.
*/
if (lopt->qlen>>(lopt->max_qlen_log-1)) {
int young = (lopt->qlen_young<<1);
while (thresh > 2) {
if (lopt->qlen < young)
break;
thresh--;
young <<= 1;
}
}
if (queue->rskq_defer_accept)
max_retries = queue->rskq_defer_accept;
budget = 2 * (lopt->nr_table_entries / (timeout / interval));
i = lopt->clock_hand;
do {
reqp=&lopt->syn_table[i];
while ((req = *reqp) != NULL) {
if (time_after_eq(now, req->expires)) {
if ((req->retrans < thresh ||
(inet_rsk(req)->acked && req->retrans < max_retries))
&& !req->rsk_ops->rtx_syn_ack(parent, req, NULL)) {
unsigned long timeo;
if (req->retrans++ == 0)
lopt->qlen_young--;
timeo = min((timeout << req->retrans), max_rto);
req->expires = now + timeo;
reqp = &req->dl_next;
continue;
}
/* Drop this request */
inet_csk_reqsk_queue_unlink(parent, req, reqp);
reqsk_queue_removed(queue, req);
reqsk_free(req);
continue;
}
reqp = &req->dl_next;
}
i = (i + 1) & (lopt->nr_table_entries - 1);
} while (--budget > 0);
lopt->clock_hand = i;
if (lopt->qlen)
inet_csk_reset_keepalive_timer(parent, interval);
}
EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_prune);
struct sock *inet_csk_clone(struct sock *sk, const struct request_sock *req,
const unsigned int __nocast priority)
{
struct sock *newsk = sk_clone(sk, priority);
if (newsk != NULL) {
struct inet_connection_sock *newicsk = inet_csk(newsk);
newsk->sk_state = TCP_SYN_RECV;
newicsk->icsk_bind_hash = NULL;
inet_sk(newsk)->dport = inet_rsk(req)->rmt_port;
newsk->sk_write_space = sk_stream_write_space;
newicsk->icsk_retransmits = 0;
newicsk->icsk_backoff = 0;
/* Deinitialize accept_queue to trap illegal accesses. */
memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
}
return newsk;
}
EXPORT_SYMBOL_GPL(inet_csk_clone);
/*
* At this point, there should be no process reference to this
* socket, and thus no user references at all. Therefore we
* can assume the socket waitqueue is inactive and nobody will
* try to jump onto it.
*/
void inet_csk_destroy_sock(struct sock *sk)
{
BUG_TRAP(sk->sk_state == TCP_CLOSE);
BUG_TRAP(sock_flag(sk, SOCK_DEAD));
/* It cannot be in hash table! */
BUG_TRAP(sk_unhashed(sk));
/* If it has not 0 inet_sk(sk)->num, it must be bound */
BUG_TRAP(!inet_sk(sk)->num || inet_csk(sk)->icsk_bind_hash);
sk->sk_prot->destroy(sk);
sk_stream_kill_queues(sk);
xfrm_sk_free_policy(sk);
sk_refcnt_debug_release(sk);
atomic_dec(sk->sk_prot->orphan_count);
sock_put(sk);
}
EXPORT_SYMBOL(inet_csk_destroy_sock);
int inet_csk_listen_start(struct sock *sk, const int nr_table_entries)
{
struct inet_sock *inet = inet_sk(sk);
struct inet_connection_sock *icsk = inet_csk(sk);
int rc = reqsk_queue_alloc(&icsk->icsk_accept_queue, nr_table_entries);
if (rc != 0)
return rc;
sk->sk_max_ack_backlog = 0;
sk->sk_ack_backlog = 0;
inet_csk_delack_init(sk);
/* There is race window here: we announce ourselves listening,
* but this transition is still not validated by get_port().
* It is OK, because this socket enters to hash table only
* after validation is complete.
*/
sk->sk_state = TCP_LISTEN;
if (!sk->sk_prot->get_port(sk, inet->num)) {
inet->sport = htons(inet->num);
sk_dst_reset(sk);
sk->sk_prot->hash(sk);
return 0;
}
sk->sk_state = TCP_CLOSE;
__reqsk_queue_destroy(&icsk->icsk_accept_queue);
return -EADDRINUSE;
}
EXPORT_SYMBOL_GPL(inet_csk_listen_start);
/*
* This routine closes sockets which have been at least partially
* opened, but not yet accepted.
*/
void inet_csk_listen_stop(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct request_sock *acc_req;
struct request_sock *req;
inet_csk_delete_keepalive_timer(sk);
/* make all the listen_opt local to us */
acc_req = reqsk_queue_yank_acceptq(&icsk->icsk_accept_queue);
/* Following specs, it would be better either to send FIN
* (and enter FIN-WAIT-1, it is normal close)
* or to send active reset (abort).
* Certainly, it is pretty dangerous while synflood, but it is
* bad justification for our negligence 8)
* To be honest, we are not able to make either
* of the variants now. --ANK
*/
reqsk_queue_destroy(&icsk->icsk_accept_queue);
while ((req = acc_req) != NULL) {
struct sock *child = req->sk;
acc_req = req->dl_next;
local_bh_disable();
bh_lock_sock(child);
BUG_TRAP(!sock_owned_by_user(child));
sock_hold(child);
sk->sk_prot->disconnect(child, O_NONBLOCK);
sock_orphan(child);
atomic_inc(sk->sk_prot->orphan_count);
inet_csk_destroy_sock(child);
bh_unlock_sock(child);
local_bh_enable();
sock_put(child);
sk_acceptq_removed(sk);
__reqsk_free(req);
}
BUG_TRAP(!sk->sk_ack_backlog);
}
EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
