v4.19.13 snapshot.
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
new file mode 100644
index 0000000..15e7f79
--- /dev/null
+++ b/net/ipv4/inet_connection_sock.c
@@ -0,0 +1,1100 @@
+/*
+ * 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/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>
+#include <net/tcp.h>
+#include <net/sock_reuseport.h>
+#include <net/addrconf.h>
+
+#if IS_ENABLED(CONFIG_IPV6)
+/* match_wildcard == true: IPV6_ADDR_ANY equals to any IPv6 addresses if IPv6
+ * only, and any IPv4 addresses if not IPv6 only
+ * match_wildcard == false: addresses must be exactly the same, i.e.
+ * IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY,
+ * and 0.0.0.0 equals to 0.0.0.0 only
+ */
+static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6,
+ const struct in6_addr *sk2_rcv_saddr6,
+ __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
+ bool sk1_ipv6only, bool sk2_ipv6only,
+ bool match_wildcard)
+{
+ int addr_type = ipv6_addr_type(sk1_rcv_saddr6);
+ int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
+
+ /* if both are mapped, treat as IPv4 */
+ if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
+ if (!sk2_ipv6only) {
+ if (sk1_rcv_saddr == sk2_rcv_saddr)
+ return true;
+ if (!sk1_rcv_saddr || !sk2_rcv_saddr)
+ return match_wildcard;
+ }
+ return false;
+ }
+
+ if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
+ return true;
+
+ if (addr_type2 == IPV6_ADDR_ANY && match_wildcard &&
+ !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
+ return true;
+
+ if (addr_type == IPV6_ADDR_ANY && match_wildcard &&
+ !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED))
+ return true;
+
+ if (sk2_rcv_saddr6 &&
+ ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6))
+ return true;
+
+ return false;
+}
+#endif
+
+/* match_wildcard == true: 0.0.0.0 equals to any IPv4 addresses
+ * match_wildcard == false: addresses must be exactly the same, i.e.
+ * 0.0.0.0 only equals to 0.0.0.0
+ */
+static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
+ bool sk2_ipv6only, bool match_wildcard)
+{
+ if (!sk2_ipv6only) {
+ if (sk1_rcv_saddr == sk2_rcv_saddr)
+ return true;
+ if (!sk1_rcv_saddr || !sk2_rcv_saddr)
+ return match_wildcard;
+ }
+ return false;
+}
+
+bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
+ bool match_wildcard)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+ if (sk->sk_family == AF_INET6)
+ return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr,
+ inet6_rcv_saddr(sk2),
+ sk->sk_rcv_saddr,
+ sk2->sk_rcv_saddr,
+ ipv6_only_sock(sk),
+ ipv6_only_sock(sk2),
+ match_wildcard);
+#endif
+ return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr,
+ ipv6_only_sock(sk2), match_wildcard);
+}
+EXPORT_SYMBOL(inet_rcv_saddr_equal);
+
+bool inet_rcv_saddr_any(const struct sock *sk)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+ if (sk->sk_family == AF_INET6)
+ return ipv6_addr_any(&sk->sk_v6_rcv_saddr);
+#endif
+ return !sk->sk_rcv_saddr;
+}
+
+void inet_get_local_port_range(struct net *net, int *low, int *high)
+{
+ unsigned int seq;
+
+ do {
+ seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
+
+ *low = net->ipv4.ip_local_ports.range[0];
+ *high = net->ipv4.ip_local_ports.range[1];
+ } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
+}
+EXPORT_SYMBOL(inet_get_local_port_range);
+
+static int inet_csk_bind_conflict(const struct sock *sk,
+ const struct inet_bind_bucket *tb,
+ bool relax, bool reuseport_ok)
+{
+ struct sock *sk2;
+ bool reuse = sk->sk_reuse;
+ bool reuseport = !!sk->sk_reuseport && reuseport_ok;
+ kuid_t uid = sock_i_uid((struct sock *)sk);
+
+ /*
+ * Unlike other sk lookup places we do not check
+ * for sk_net here, since _all_ the socks listed
+ * in tb->owners list belong to the same net - the
+ * one this bucket belongs to.
+ */
+
+ sk_for_each_bound(sk2, &tb->owners) {
+ if (sk != 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) &&
+ (!reuseport || !sk2->sk_reuseport ||
+ rcu_access_pointer(sk->sk_reuseport_cb) ||
+ (sk2->sk_state != TCP_TIME_WAIT &&
+ !uid_eq(uid, sock_i_uid(sk2))))) {
+ if (inet_rcv_saddr_equal(sk, sk2, true))
+ break;
+ }
+ if (!relax && reuse && sk2->sk_reuse &&
+ sk2->sk_state != TCP_LISTEN) {
+ if (inet_rcv_saddr_equal(sk, sk2, true))
+ break;
+ }
+ }
+ }
+ return sk2 != NULL;
+}
+
+/*
+ * Find an open port number for the socket. Returns with the
+ * inet_bind_hashbucket lock held.
+ */
+static struct inet_bind_hashbucket *
+inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret)
+{
+ struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
+ int port = 0;
+ struct inet_bind_hashbucket *head;
+ struct net *net = sock_net(sk);
+ int i, low, high, attempt_half;
+ struct inet_bind_bucket *tb;
+ u32 remaining, offset;
+
+ attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
+other_half_scan:
+ inet_get_local_port_range(net, &low, &high);
+ high++; /* [32768, 60999] -> [32768, 61000[ */
+ if (high - low < 4)
+ attempt_half = 0;
+ if (attempt_half) {
+ int half = low + (((high - low) >> 2) << 1);
+
+ if (attempt_half == 1)
+ high = half;
+ else
+ low = half;
+ }
+ remaining = high - low;
+ if (likely(remaining > 1))
+ remaining &= ~1U;
+
+ offset = prandom_u32() % remaining;
+ /* __inet_hash_connect() favors ports having @low parity
+ * We do the opposite to not pollute connect() users.
+ */
+ offset |= 1U;
+
+other_parity_scan:
+ port = low + offset;
+ for (i = 0; i < remaining; i += 2, port += 2) {
+ if (unlikely(port >= high))
+ port -= remaining;
+ if (inet_is_local_reserved_port(net, port))
+ continue;
+ head = &hinfo->bhash[inet_bhashfn(net, port,
+ hinfo->bhash_size)];
+ spin_lock_bh(&head->lock);
+ inet_bind_bucket_for_each(tb, &head->chain)
+ if (net_eq(ib_net(tb), net) && tb->port == port) {
+ if (!inet_csk_bind_conflict(sk, tb, false, false))
+ goto success;
+ goto next_port;
+ }
+ tb = NULL;
+ goto success;
+next_port:
+ spin_unlock_bh(&head->lock);
+ cond_resched();
+ }
+
+ offset--;
+ if (!(offset & 1))
+ goto other_parity_scan;
+
+ if (attempt_half == 1) {
+ /* OK we now try the upper half of the range */
+ attempt_half = 2;
+ goto other_half_scan;
+ }
+ return NULL;
+success:
+ *port_ret = port;
+ *tb_ret = tb;
+ return head;
+}
+
+static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
+ struct sock *sk)
+{
+ kuid_t uid = sock_i_uid(sk);
+
+ if (tb->fastreuseport <= 0)
+ return 0;
+ if (!sk->sk_reuseport)
+ return 0;
+ if (rcu_access_pointer(sk->sk_reuseport_cb))
+ return 0;
+ if (!uid_eq(tb->fastuid, uid))
+ return 0;
+ /* We only need to check the rcv_saddr if this tb was once marked
+ * without fastreuseport and then was reset, as we can only know that
+ * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
+ * owners list.
+ */
+ if (tb->fastreuseport == FASTREUSEPORT_ANY)
+ return 1;
+#if IS_ENABLED(CONFIG_IPV6)
+ if (tb->fast_sk_family == AF_INET6)
+ return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
+ inet6_rcv_saddr(sk),
+ tb->fast_rcv_saddr,
+ sk->sk_rcv_saddr,
+ tb->fast_ipv6_only,
+ ipv6_only_sock(sk), true);
+#endif
+ return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
+ ipv6_only_sock(sk), true);
+}
+
+/* Obtain a reference to a local port for the given sock,
+ * if snum is zero it means select any available local port.
+ * We try to allocate an odd port (and leave even ports for connect())
+ */
+int inet_csk_get_port(struct sock *sk, unsigned short snum)
+{
+ bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
+ struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
+ int ret = 1, port = snum;
+ struct inet_bind_hashbucket *head;
+ struct net *net = sock_net(sk);
+ struct inet_bind_bucket *tb = NULL;
+ kuid_t uid = sock_i_uid(sk);
+
+ if (!port) {
+ head = inet_csk_find_open_port(sk, &tb, &port);
+ if (!head)
+ return ret;
+ if (!tb)
+ goto tb_not_found;
+ goto success;
+ }
+ head = &hinfo->bhash[inet_bhashfn(net, port,
+ hinfo->bhash_size)];
+ spin_lock_bh(&head->lock);
+ inet_bind_bucket_for_each(tb, &head->chain)
+ if (net_eq(ib_net(tb), net) && tb->port == port)
+ goto tb_found;
+tb_not_found:
+ tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
+ net, head, port);
+ if (!tb)
+ goto fail_unlock;
+tb_found:
+ if (!hlist_empty(&tb->owners)) {
+ if (sk->sk_reuse == SK_FORCE_REUSE)
+ goto success;
+
+ if ((tb->fastreuse > 0 && reuse) ||
+ sk_reuseport_match(tb, sk))
+ goto success;
+ if (inet_csk_bind_conflict(sk, tb, true, true))
+ goto fail_unlock;
+ }
+success:
+ if (hlist_empty(&tb->owners)) {
+ tb->fastreuse = reuse;
+ if (sk->sk_reuseport) {
+ tb->fastreuseport = FASTREUSEPORT_ANY;
+ tb->fastuid = uid;
+ tb->fast_rcv_saddr = sk->sk_rcv_saddr;
+ tb->fast_ipv6_only = ipv6_only_sock(sk);
+ tb->fast_sk_family = sk->sk_family;
+#if IS_ENABLED(CONFIG_IPV6)
+ tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
+#endif
+ } else {
+ tb->fastreuseport = 0;
+ }
+ } else {
+ if (!reuse)
+ tb->fastreuse = 0;
+ if (sk->sk_reuseport) {
+ /* We didn't match or we don't have fastreuseport set on
+ * the tb, but we have sk_reuseport set on this socket
+ * and we know that there are no bind conflicts with
+ * this socket in this tb, so reset our tb's reuseport
+ * settings so that any subsequent sockets that match
+ * our current socket will be put on the fast path.
+ *
+ * If we reset we need to set FASTREUSEPORT_STRICT so we
+ * do extra checking for all subsequent sk_reuseport
+ * socks.
+ */
+ if (!sk_reuseport_match(tb, sk)) {
+ tb->fastreuseport = FASTREUSEPORT_STRICT;
+ tb->fastuid = uid;
+ tb->fast_rcv_saddr = sk->sk_rcv_saddr;
+ tb->fast_ipv6_only = ipv6_only_sock(sk);
+ tb->fast_sk_family = sk->sk_family;
+#if IS_ENABLED(CONFIG_IPV6)
+ tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
+#endif
+ }
+ } else {
+ tb->fastreuseport = 0;
+ }
+ }
+ if (!inet_csk(sk)->icsk_bind_hash)
+ inet_bind_hash(sk, tb, port);
+ WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
+ ret = 0;
+
+fail_unlock:
+ spin_unlock_bh(&head->lock);
+ 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_sleep(sk), &wait,
+ TASK_INTERRUPTIBLE);
+ release_sock(sk);
+ if (reqsk_queue_empty(&icsk->icsk_accept_queue))
+ timeo = schedule_timeout(timeo);
+ sched_annotate_sleep();
+ 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_sleep(sk), &wait);
+ return err;
+}
+
+/*
+ * This will accept the next outstanding connection.
+ */
+struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ struct request_sock_queue *queue = &icsk->icsk_accept_queue;
+ struct request_sock *req;
+ 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(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;
+ }
+ req = reqsk_queue_remove(queue, sk);
+ newsk = req->sk;
+
+ if (sk->sk_protocol == IPPROTO_TCP &&
+ tcp_rsk(req)->tfo_listener) {
+ spin_lock_bh(&queue->fastopenq.lock);
+ if (tcp_rsk(req)->tfo_listener) {
+ /* We are still waiting for the final ACK from 3WHS
+ * so can't free req now. Instead, we set req->sk to
+ * NULL to signify that the child socket is taken
+ * so reqsk_fastopen_remove() will free the req
+ * when 3WHS finishes (or is aborted).
+ */
+ req->sk = NULL;
+ req = NULL;
+ }
+ spin_unlock_bh(&queue->fastopenq.lock);
+ }
+out:
+ release_sock(sk);
+ if (req)
+ reqsk_put(req);
+ return newsk;
+out_err:
+ newsk = NULL;
+ req = 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)(struct timer_list *t),
+ void (*delack_handler)(struct timer_list *t),
+ void (*keepalive_handler)(struct timer_list *t))
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+
+ timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
+ timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
+ timer_setup(&sk->sk_timer, keepalive_handler, 0);
+ 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(const struct sock *sk,
+ struct flowi4 *fl4,
+ const struct request_sock *req)
+{
+ const struct inet_request_sock *ireq = inet_rsk(req);
+ struct net *net = read_pnet(&ireq->ireq_net);
+ struct ip_options_rcu *opt;
+ struct rtable *rt;
+
+ rcu_read_lock();
+ opt = rcu_dereference(ireq->ireq_opt);
+
+ flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
+ RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
+ sk->sk_protocol, inet_sk_flowi_flags(sk),
+ (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
+ ireq->ir_loc_addr, ireq->ir_rmt_port,
+ htons(ireq->ir_num), sk->sk_uid);
+ security_req_classify_flow(req, flowi4_to_flowi(fl4));
+ rt = ip_route_output_flow(net, fl4, sk);
+ if (IS_ERR(rt))
+ goto no_route;
+ if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
+ goto route_err;
+ rcu_read_unlock();
+ return &rt->dst;
+
+route_err:
+ ip_rt_put(rt);
+no_route:
+ rcu_read_unlock();
+ __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(inet_csk_route_req);
+
+struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
+ struct sock *newsk,
+ const struct request_sock *req)
+{
+ const struct inet_request_sock *ireq = inet_rsk(req);
+ struct net *net = read_pnet(&ireq->ireq_net);
+ struct inet_sock *newinet = inet_sk(newsk);
+ struct ip_options_rcu *opt;
+ struct flowi4 *fl4;
+ struct rtable *rt;
+
+ opt = rcu_dereference(ireq->ireq_opt);
+ fl4 = &newinet->cork.fl.u.ip4;
+
+ flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
+ RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
+ sk->sk_protocol, inet_sk_flowi_flags(sk),
+ (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
+ ireq->ir_loc_addr, ireq->ir_rmt_port,
+ htons(ireq->ir_num), sk->sk_uid);
+ security_req_classify_flow(req, flowi4_to_flowi(fl4));
+ rt = ip_route_output_flow(net, fl4, sk);
+ if (IS_ERR(rt))
+ goto no_route;
+ if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
+ goto route_err;
+ return &rt->dst;
+
+route_err:
+ ip_rt_put(rt);
+no_route:
+ __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
+ return NULL;
+}
+EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
+
+#if IS_ENABLED(CONFIG_IPV6)
+#define AF_INET_FAMILY(fam) ((fam) == AF_INET)
+#else
+#define AF_INET_FAMILY(fam) true
+#endif
+
+/* Decide when to expire the request and when to resend SYN-ACK */
+static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
+ const int max_retries,
+ const u8 rskq_defer_accept,
+ int *expire, int *resend)
+{
+ if (!rskq_defer_accept) {
+ *expire = req->num_timeout >= thresh;
+ *resend = 1;
+ return;
+ }
+ *expire = req->num_timeout >= thresh &&
+ (!inet_rsk(req)->acked || req->num_timeout >= max_retries);
+ /*
+ * Do not resend while waiting for data after ACK,
+ * start to resend on end of deferring period to give
+ * last chance for data or ACK to create established socket.
+ */
+ *resend = !inet_rsk(req)->acked ||
+ req->num_timeout >= rskq_defer_accept - 1;
+}
+
+int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
+{
+ int err = req->rsk_ops->rtx_syn_ack(parent, req);
+
+ if (!err)
+ req->num_retrans++;
+ return err;
+}
+EXPORT_SYMBOL(inet_rtx_syn_ack);
+
+/* return true if req was found in the ehash table */
+static bool reqsk_queue_unlink(struct request_sock_queue *queue,
+ struct request_sock *req)
+{
+ struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
+ bool found = false;
+
+ if (sk_hashed(req_to_sk(req))) {
+ spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
+
+ spin_lock(lock);
+ found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
+ spin_unlock(lock);
+ }
+ if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
+ reqsk_put(req);
+ return found;
+}
+
+void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
+{
+ if (reqsk_queue_unlink(&inet_csk(sk)->icsk_accept_queue, req)) {
+ reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
+ reqsk_put(req);
+ }
+}
+EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
+
+void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
+{
+ inet_csk_reqsk_queue_drop(sk, req);
+ reqsk_put(req);
+}
+EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
+
+static void reqsk_timer_handler(struct timer_list *t)
+{
+ struct request_sock *req = from_timer(req, t, rsk_timer);
+ struct sock *sk_listener = req->rsk_listener;
+ struct net *net = sock_net(sk_listener);
+ struct inet_connection_sock *icsk = inet_csk(sk_listener);
+ struct request_sock_queue *queue = &icsk->icsk_accept_queue;
+ int qlen, expire = 0, resend = 0;
+ int max_retries, thresh;
+ u8 defer_accept;
+
+ if (inet_sk_state_load(sk_listener) != TCP_LISTEN)
+ goto drop;
+
+ max_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
+ thresh = max_retries;
+ /* Normally all the openreqs are young and become mature
+ * (i.e. converted to established socket) for first timeout.
+ * If synack was not acknowledged for 1 second, 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.
+ */
+ qlen = reqsk_queue_len(queue);
+ if ((qlen << 1) > max(8U, sk_listener->sk_max_ack_backlog)) {
+ int young = reqsk_queue_len_young(queue) << 1;
+
+ while (thresh > 2) {
+ if (qlen < young)
+ break;
+ thresh--;
+ young <<= 1;
+ }
+ }
+ defer_accept = READ_ONCE(queue->rskq_defer_accept);
+ if (defer_accept)
+ max_retries = defer_accept;
+ syn_ack_recalc(req, thresh, max_retries, defer_accept,
+ &expire, &resend);
+ req->rsk_ops->syn_ack_timeout(req);
+ if (!expire &&
+ (!resend ||
+ !inet_rtx_syn_ack(sk_listener, req) ||
+ inet_rsk(req)->acked)) {
+ unsigned long timeo;
+
+ if (req->num_timeout++ == 0)
+ atomic_dec(&queue->young);
+ timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
+ mod_timer(&req->rsk_timer, jiffies + timeo);
+ return;
+ }
+drop:
+ inet_csk_reqsk_queue_drop_and_put(sk_listener, req);
+}
+
+static void reqsk_queue_hash_req(struct request_sock *req,
+ unsigned long timeout)
+{
+ req->num_retrans = 0;
+ req->num_timeout = 0;
+ req->sk = NULL;
+
+ timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
+ mod_timer(&req->rsk_timer, jiffies + timeout);
+
+ inet_ehash_insert(req_to_sk(req), NULL);
+ /* before letting lookups find us, make sure all req fields
+ * are committed to memory and refcnt initialized.
+ */
+ smp_wmb();
+ refcount_set(&req->rsk_refcnt, 2 + 1);
+}
+
+void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
+ unsigned long timeout)
+{
+ reqsk_queue_hash_req(req, timeout);
+ inet_csk_reqsk_queue_added(sk);
+}
+EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
+
+/**
+ * inet_csk_clone_lock - clone an inet socket, and lock its clone
+ * @sk: the socket to clone
+ * @req: request_sock
+ * @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
+ *
+ * Caller must unlock socket even in error path (bh_unlock_sock(newsk))
+ */
+struct sock *inet_csk_clone_lock(const struct sock *sk,
+ const struct request_sock *req,
+ const gfp_t priority)
+{
+ struct sock *newsk = sk_clone_lock(sk, priority);
+
+ if (newsk) {
+ struct inet_connection_sock *newicsk = inet_csk(newsk);
+
+ inet_sk_set_state(newsk, TCP_SYN_RECV);
+ newicsk->icsk_bind_hash = NULL;
+
+ inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
+ inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
+ inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
+
+ /* listeners have SOCK_RCU_FREE, not the children */
+ sock_reset_flag(newsk, SOCK_RCU_FREE);
+
+ inet_sk(newsk)->mc_list = NULL;
+
+ newsk->sk_mark = inet_rsk(req)->ir_mark;
+ atomic64_set(&newsk->sk_cookie,
+ atomic64_read(&inet_rsk(req)->ir_cookie));
+
+ newicsk->icsk_retransmits = 0;
+ newicsk->icsk_backoff = 0;
+ newicsk->icsk_probes_out = 0;
+
+ /* Deinitialize accept_queue to trap illegal accesses. */
+ memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
+
+ security_inet_csk_clone(newsk, req);
+ }
+ return newsk;
+}
+EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
+
+/*
+ * 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)
+{
+ WARN_ON(sk->sk_state != TCP_CLOSE);
+ WARN_ON(!sock_flag(sk, SOCK_DEAD));
+
+ /* It cannot be in hash table! */
+ WARN_ON(!sk_unhashed(sk));
+
+ /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
+ WARN_ON(inet_sk(sk)->inet_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);
+
+ percpu_counter_dec(sk->sk_prot->orphan_count);
+
+ sock_put(sk);
+}
+EXPORT_SYMBOL(inet_csk_destroy_sock);
+
+/* This function allows to force a closure of a socket after the call to
+ * tcp/dccp_create_openreq_child().
+ */
+void inet_csk_prepare_forced_close(struct sock *sk)
+ __releases(&sk->sk_lock.slock)
+{
+ /* sk_clone_lock locked the socket and set refcnt to 2 */
+ bh_unlock_sock(sk);
+ sock_put(sk);
+
+ /* The below has to be done to allow calling inet_csk_destroy_sock */
+ sock_set_flag(sk, SOCK_DEAD);
+ percpu_counter_inc(sk->sk_prot->orphan_count);
+ inet_sk(sk)->inet_num = 0;
+}
+EXPORT_SYMBOL(inet_csk_prepare_forced_close);
+
+int inet_csk_listen_start(struct sock *sk, int backlog)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ struct inet_sock *inet = inet_sk(sk);
+ int err = -EADDRINUSE;
+
+ reqsk_queue_alloc(&icsk->icsk_accept_queue);
+
+ sk->sk_max_ack_backlog = backlog;
+ 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.
+ */
+ inet_sk_state_store(sk, TCP_LISTEN);
+ if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
+ inet->inet_sport = htons(inet->inet_num);
+
+ sk_dst_reset(sk);
+ err = sk->sk_prot->hash(sk);
+
+ if (likely(!err))
+ return 0;
+ }
+
+ inet_sk_set_state(sk, TCP_CLOSE);
+ return err;
+}
+EXPORT_SYMBOL_GPL(inet_csk_listen_start);
+
+static void inet_child_forget(struct sock *sk, struct request_sock *req,
+ struct sock *child)
+{
+ sk->sk_prot->disconnect(child, O_NONBLOCK);
+
+ sock_orphan(child);
+
+ percpu_counter_inc(sk->sk_prot->orphan_count);
+
+ if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
+ BUG_ON(tcp_sk(child)->fastopen_rsk != req);
+ BUG_ON(sk != req->rsk_listener);
+
+ /* Paranoid, to prevent race condition if
+ * an inbound pkt destined for child is
+ * blocked by sock lock in tcp_v4_rcv().
+ * Also to satisfy an assertion in
+ * tcp_v4_destroy_sock().
+ */
+ tcp_sk(child)->fastopen_rsk = NULL;
+ }
+ inet_csk_destroy_sock(child);
+}
+
+struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
+ struct request_sock *req,
+ struct sock *child)
+{
+ struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
+
+ spin_lock(&queue->rskq_lock);
+ if (unlikely(sk->sk_state != TCP_LISTEN)) {
+ inet_child_forget(sk, req, child);
+ child = NULL;
+ } else {
+ req->sk = child;
+ req->dl_next = NULL;
+ if (queue->rskq_accept_head == NULL)
+ queue->rskq_accept_head = req;
+ else
+ queue->rskq_accept_tail->dl_next = req;
+ queue->rskq_accept_tail = req;
+ sk_acceptq_added(sk);
+ }
+ spin_unlock(&queue->rskq_lock);
+ return child;
+}
+EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
+
+struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
+ struct request_sock *req, bool own_req)
+{
+ if (own_req) {
+ inet_csk_reqsk_queue_drop(sk, req);
+ reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
+ if (inet_csk_reqsk_queue_add(sk, req, child))
+ return child;
+ }
+ /* Too bad, another child took ownership of the request, undo. */
+ bh_unlock_sock(child);
+ sock_put(child);
+ return NULL;
+}
+EXPORT_SYMBOL(inet_csk_complete_hashdance);
+
+/*
+ * 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_queue *queue = &icsk->icsk_accept_queue;
+ struct request_sock *next, *req;
+
+ /* 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
+ */
+ while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
+ struct sock *child = req->sk;
+
+ local_bh_disable();
+ bh_lock_sock(child);
+ WARN_ON(sock_owned_by_user(child));
+ sock_hold(child);
+
+ inet_child_forget(sk, req, child);
+ reqsk_put(req);
+ bh_unlock_sock(child);
+ local_bh_enable();
+ sock_put(child);
+
+ cond_resched();
+ }
+ if (queue->fastopenq.rskq_rst_head) {
+ /* Free all the reqs queued in rskq_rst_head. */
+ spin_lock_bh(&queue->fastopenq.lock);
+ req = queue->fastopenq.rskq_rst_head;
+ queue->fastopenq.rskq_rst_head = NULL;
+ spin_unlock_bh(&queue->fastopenq.lock);
+ while (req != NULL) {
+ next = req->dl_next;
+ reqsk_put(req);
+ req = next;
+ }
+ }
+ WARN_ON_ONCE(sk->sk_ack_backlog);
+}
+EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
+
+void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
+{
+ struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
+ const struct inet_sock *inet = inet_sk(sk);
+
+ sin->sin_family = AF_INET;
+ sin->sin_addr.s_addr = inet->inet_daddr;
+ sin->sin_port = inet->inet_dport;
+}
+EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
+
+#ifdef CONFIG_COMPAT
+int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
+ char __user *optval, int __user *optlen)
+{
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+
+ if (icsk->icsk_af_ops->compat_getsockopt)
+ return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
+ optval, optlen);
+ return icsk->icsk_af_ops->getsockopt(sk, level, optname,
+ optval, optlen);
+}
+EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
+
+int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
+ char __user *optval, unsigned int optlen)
+{
+ const struct inet_connection_sock *icsk = inet_csk(sk);
+
+ if (icsk->icsk_af_ops->compat_setsockopt)
+ return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
+ optval, optlen);
+ return icsk->icsk_af_ops->setsockopt(sk, level, optname,
+ optval, optlen);
+}
+EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
+#endif
+
+static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
+{
+ const struct inet_sock *inet = inet_sk(sk);
+ const struct ip_options_rcu *inet_opt;
+ __be32 daddr = inet->inet_daddr;
+ struct flowi4 *fl4;
+ struct rtable *rt;
+
+ rcu_read_lock();
+ inet_opt = rcu_dereference(inet->inet_opt);
+ if (inet_opt && inet_opt->opt.srr)
+ daddr = inet_opt->opt.faddr;
+ fl4 = &fl->u.ip4;
+ rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
+ inet->inet_saddr, inet->inet_dport,
+ inet->inet_sport, sk->sk_protocol,
+ RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
+ if (IS_ERR(rt))
+ rt = NULL;
+ if (rt)
+ sk_setup_caps(sk, &rt->dst);
+ rcu_read_unlock();
+
+ return &rt->dst;
+}
+
+struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
+{
+ struct dst_entry *dst = __sk_dst_check(sk, 0);
+ struct inet_sock *inet = inet_sk(sk);
+
+ if (!dst) {
+ dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
+ if (!dst)
+ goto out;
+ }
+ dst->ops->update_pmtu(dst, sk, NULL, mtu);
+
+ dst = __sk_dst_check(sk, 0);
+ if (!dst)
+ dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
+out:
+ return dst;
+}
+EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);