diff options
Diffstat (limited to 'net/ipv4/inet_connection_sock.c')
| -rw-r--r-- | net/ipv4/inet_connection_sock.c | 1138 |
1 files changed, 1138 insertions, 0 deletions
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c new file mode 100644 index 000000000..5f71a1c74 --- /dev/null +++ b/net/ipv4/inet_connection_sock.c @@ -0,0 +1,1138 @@ +// 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 reuse = sk->sk_reuse; + bool reuseport = !!sk->sk_reuseport; + 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) { + int bound_dev_if2; + + if (sk == sk2) + continue; + bound_dev_if2 = READ_ONCE(sk2->sk_bound_dev_if); + if ((!sk->sk_bound_dev_if || + !bound_dev_if2 || + sk->sk_bound_dev_if == bound_dev_if2)) { + if (reuse && sk2->sk_reuse && + sk2->sk_state != TCP_LISTEN) { + if ((!relax || + (!reuseport_ok && + reuseport && sk2->sk_reuseport && + !rcu_access_pointer(sk->sk_reuseport_cb) && + (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 || + 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; + } + } + } + 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 (READ_ONCE(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); + + 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); + +/* 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 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 max_syn_ack_retries, qlen, expire = 0, resend = 0; + + if (inet_sk_state_load(sk_listener) != TCP_LISTEN) + goto drop; + + max_syn_ack_retries = READ_ONCE(icsk->icsk_syn_retries) ? : + READ_ONCE(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. + */ + 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); + 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) +{ + 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); + + newsk->sk_wait_pending = 0; + 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) +{ + 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); + + this_cpu_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); + inet_csk_prepare_for_destroy_sock(sk); + inet_sk(sk)->inet_num = 0; +} +EXPORT_SYMBOL(inet_csk_prepare_forced_close); + +static int inet_ulp_can_listen(const struct sock *sk) +{ + const struct inet_connection_sock *icsk = inet_csk(sk); + + if (icsk->icsk_ulp_ops && !icsk->icsk_ulp_ops->clone) + return -EINVAL; + + return 0; +} + +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; + + err = inet_ulp_can_listen(sk); + if (unlikely(err)) + return err; + + reqsk_queue_alloc(&icsk->icsk_accept_queue); + + 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. + */ + err = -EADDRINUSE; + 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); + + this_cpu_inc(*sk->sk_prot->orphan_count); + + if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) { + BUG_ON(rcu_access_pointer(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(). + */ + RCU_INIT_POINTER(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) + WRITE_ONCE(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); + +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, true); + + 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); |