/
inet_connection_sock.c
1296 lines (1134 loc) · 35.6 KB
/
inet_connection_sock.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* 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
*/
#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_sk*_wildcard == true: IPV6_ADDR_ANY equals to any IPv6 addresses
* if IPv6 only, and any IPv4 addresses
* if not IPv6 only
* match_sk*_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_sk1_wildcard,
bool match_sk2_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;
return (match_sk1_wildcard && !sk1_rcv_saddr) ||
(match_sk2_wildcard && !sk2_rcv_saddr);
}
return false;
}
if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
return true;
if (addr_type2 == IPV6_ADDR_ANY && match_sk2_wildcard &&
!(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
return true;
if (addr_type == IPV6_ADDR_ANY && match_sk1_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_sk*_wildcard == true: 0.0.0.0 equals to any IPv4 addresses
* match_sk*_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_sk1_wildcard,
bool match_sk2_wildcard)
{
if (!sk2_ipv6only) {
if (sk1_rcv_saddr == sk2_rcv_saddr)
return true;
return (match_sk1_wildcard && !sk1_rcv_saddr) ||
(match_sk2_wildcard && !sk2_rcv_saddr);
}
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,
match_wildcard);
#endif
return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr,
ipv6_only_sock(sk2), match_wildcard,
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 reuseport_cb_ok;
bool reuse = sk->sk_reuse;
bool reuseport = !!sk->sk_reuseport;
struct sock_reuseport *reuseport_cb;
kuid_t uid = sock_i_uid((struct sock *)sk);
rcu_read_lock();
reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
/* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
rcu_read_unlock();
/*
* 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) {
if ((!relax ||
(!reuseport_ok &&
reuseport && sk2->sk_reuseport &&
reuseport_cb_ok &&
(sk2->sk_state == TCP_TIME_WAIT ||
uid_eq(uid, sock_i_uid(sk2))))) &&
inet_rcv_saddr_equal(sk, sk2, true))
break;
} else if (!reuseport_ok ||
!reuseport || !sk2->sk_reuseport ||
!reuseport_cb_ok ||
(sk2->sk_state != TCP_TIME_WAIT &&
!uid_eq(uid, sock_i_uid(sk2)))) {
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);
bool relax = false;
int i, low, high, attempt_half;
struct inet_bind_bucket *tb;
u32 remaining, offset;
int l3mdev;
l3mdev = inet_sk_bound_l3mdev(sk);
ports_exhausted:
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->l3mdev == l3mdev &&
tb->port == port) {
if (!inet_csk_bind_conflict(sk, tb, relax, 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;
}
if (net->ipv4.sysctl_ip_autobind_reuse && !relax) {
/* We still have a chance to connect to different destinations */
relax = true;
goto ports_exhausted;
}
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, false);
#endif
return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
ipv6_only_sock(sk), true, false);
}
void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
struct sock *sk)
{
kuid_t uid = sock_i_uid(sk);
bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
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;
}
}
}
/* 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;
int l3mdev;
l3mdev = inet_sk_bound_l3mdev(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->l3mdev == l3mdev &&
tb->port == port)
goto tb_found;
tb_not_found:
tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
net, head, port, l3mdev);
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:
inet_csk_update_fastreuse(tb, sk);
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 (newsk && mem_cgroup_sockets_enabled) {
int amt;
/* atomically get the memory usage, set and charge the
* newsk->sk_memcg.
*/
lock_sock(newsk);
/* The socket has not been accepted yet, no need to look at
* newsk->sk_wmem_queued.
*/
amt = sk_mem_pages(newsk->sk_forward_alloc +
atomic_read(&newsk->sk_rmem_alloc));
mem_cgroup_sk_alloc(newsk);
if (newsk->sk_memcg && amt)
mem_cgroup_charge_skmem(newsk->sk_memcg, amt,
GFP_KERNEL | __GFP_NOFAIL);
release_sock(newsk);
}
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 = 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_common(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_common(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);
/* Decide when to expire the request and when to resend SYN-ACK */
static void syn_ack_recalc(struct request_sock *req,
const int max_syn_ack_retries,
const u8 rskq_defer_accept,
int *expire, int *resend)
{
if (!rskq_defer_accept) {
*expire = req->num_timeout >= max_syn_ack_retries;
*resend = 1;
return;
}
*expire = req->num_timeout >= max_syn_ack_retries &&
(!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
/* 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);
static struct request_sock *inet_reqsk_clone(struct request_sock *req,
struct sock *sk)
{
struct sock *req_sk, *nreq_sk;
struct request_sock *nreq;
nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
if (!nreq) {
__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
/* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
sock_put(sk);
return NULL;
}
req_sk = req_to_sk(req);
nreq_sk = req_to_sk(nreq);
memcpy(nreq_sk, req_sk,
offsetof(struct sock, sk_dontcopy_begin));
memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end));
sk_node_init(&nreq_sk->sk_node);
nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
#ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
#endif
nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
nreq->rsk_listener = sk;
/* We need not acquire fastopenq->lock
* because the child socket is locked in inet_csk_listen_stop().
*/
if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
return nreq;
}
static void reqsk_queue_migrated(struct request_sock_queue *queue,
const struct request_sock *req)
{
if (req->num_timeout == 0)
atomic_inc(&queue->young);
atomic_inc(&queue->qlen);
}
static void reqsk_migrate_reset(struct request_sock *req)
{
req->saved_syn = NULL;
#if IS_ENABLED(CONFIG_IPV6)
inet_rsk(req)->ipv6_opt = NULL;
inet_rsk(req)->pktopts = NULL;
#else
inet_rsk(req)->ireq_opt = NULL;
#endif
}
/* return true if req was found in the ehash table */
static bool reqsk_queue_unlink(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;
}
bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
{
bool unlinked = reqsk_queue_unlink(req);
if (unlinked) {
reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
reqsk_put(req);
}
return unlinked;
}
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 request_sock *nreq = NULL, *oreq = req;
struct sock *sk_listener = req->rsk_listener;
struct inet_connection_sock *icsk;
struct request_sock_queue *queue;
struct net *net;
int max_syn_ack_retries, qlen, expire = 0, resend = 0;
if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
struct sock *nsk;
nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
if (!nsk)
goto drop;
nreq = inet_reqsk_clone(req, nsk);
if (!nreq)
goto drop;
/* The new timer for the cloned req can decrease the 2
* by calling inet_csk_reqsk_queue_drop_and_put(), so
* hold another count to prevent use-after-free and
* call reqsk_put() just before return.
*/
refcount_set(&nreq->rsk_refcnt, 2 + 1);
timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
req = nreq;
sk_listener = nsk;
}
icsk = inet_csk(sk_listener);
net = sock_net(sk_listener);
max_syn_ack_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_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.
*/
queue = &icsk->icsk_accept_queue;
qlen = reqsk_queue_len(queue);
if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
int young = reqsk_queue_len_young(queue) << 1;
while (max_syn_ack_retries > 2) {
if (qlen < young)
break;
max_syn_ack_retries--;
young <<= 1;
}
}
syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_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);
if (!nreq)
return;
if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
/* delete timer */
inet_csk_reqsk_queue_drop(sk_listener, nreq);
goto no_ownership;
}
__NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);
reqsk_migrate_reset(oreq);
reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
reqsk_put(oreq);
reqsk_put(nreq);
return;
}
/* Even if we can clone the req, we may need not retransmit any more
* SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
* CPU may win the "own_req" race so that inet_ehash_insert() fails.
*/
if (nreq) {
__NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
no_ownership:
reqsk_migrate_reset(nreq);
reqsk_queue_removed(queue, nreq);
__reqsk_free(nreq);
}
drop:
inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);
}
static void reqsk_queue_hash_req(struct request_sock *req,
unsigned long timeout)
{
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, 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);
static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
const gfp_t priority)
{
struct inet_connection_sock *icsk = inet_csk(newsk);
if (!icsk->icsk_ulp_ops)
return;
if (icsk->icsk_ulp_ops->clone)
icsk->icsk_ulp_ops->clone(req, newsk, priority);
}
/**
* 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;
newicsk->icsk_probes_tstamp = 0;
/* Deinitialize accept_queue to trap illegal accesses. */
memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
inet_clone_ulp(req, newsk, priority);
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)
{