// 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 #include #include #include #include #include #include #include #include #include #include #include #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 bool inet_use_bhash2_on_bind(const struct sock *sk) { #if IS_ENABLED(CONFIG_IPV6) if (sk->sk_family == AF_INET6) { int addr_type = ipv6_addr_type(&sk->sk_v6_rcv_saddr); return addr_type != IPV6_ADDR_ANY && addr_type != IPV6_ADDR_MAPPED; } #endif return sk->sk_rcv_saddr != htonl(INADDR_ANY); } static bool inet_bind_conflict(const struct sock *sk, struct sock *sk2, kuid_t sk_uid, bool relax, bool reuseport_cb_ok, bool reuseport_ok) { int bound_dev_if2; if (sk == sk2) return false; 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 (sk->sk_reuse && sk2->sk_reuse && sk2->sk_state != TCP_LISTEN) { if (!relax || (!reuseport_ok && sk->sk_reuseport && sk2->sk_reuseport && reuseport_cb_ok && (sk2->sk_state == TCP_TIME_WAIT || uid_eq(sk_uid, sock_i_uid(sk2))))) return true; } else if (!reuseport_ok || !sk->sk_reuseport || !sk2->sk_reuseport || !reuseport_cb_ok || (sk2->sk_state != TCP_TIME_WAIT && !uid_eq(sk_uid, sock_i_uid(sk2)))) { return true; } } return false; } static bool inet_bhash2_conflict(const struct sock *sk, const struct inet_bind2_bucket *tb2, kuid_t sk_uid, bool relax, bool reuseport_cb_ok, bool reuseport_ok) { struct sock *sk2; sk_for_each_bound_bhash2(sk2, &tb2->owners) { if (sk->sk_family == AF_INET && ipv6_only_sock(sk2)) continue; if (inet_bind_conflict(sk, sk2, sk_uid, relax, reuseport_cb_ok, reuseport_ok)) return true; } return false; } /* This should be called only when the tb and tb2 hashbuckets' locks are held */ static int inet_csk_bind_conflict(const struct sock *sk, const struct inet_bind_bucket *tb, const struct inet_bind2_bucket *tb2, /* may be null */ bool relax, bool reuseport_ok) { bool reuseport_cb_ok; 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 and tb2->owners list belong * to the same net - the one this bucket belongs to. */ if (!inet_use_bhash2_on_bind(sk)) { struct sock *sk2; sk_for_each_bound(sk2, &tb->owners) if (inet_bind_conflict(sk, sk2, uid, relax, reuseport_cb_ok, reuseport_ok) && inet_rcv_saddr_equal(sk, sk2, true)) return true; return false; } /* Conflicts with an existing IPV6_ADDR_ANY (if ipv6) or INADDR_ANY (if * ipv4) should have been checked already. We need to do these two * checks separately because their spinlocks have to be acquired/released * independently of each other, to prevent possible deadlocks */ return tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok, reuseport_ok); } /* Determine if there is a bind conflict with an existing IPV6_ADDR_ANY (if ipv6) or * INADDR_ANY (if ipv4) socket. * * Caller must hold bhash hashbucket lock with local bh disabled, to protect * against concurrent binds on the port for addr any */ static bool inet_bhash2_addr_any_conflict(const struct sock *sk, int port, int l3mdev, bool relax, bool reuseport_ok) { kuid_t uid = sock_i_uid((struct sock *)sk); const struct net *net = sock_net(sk); struct sock_reuseport *reuseport_cb; struct inet_bind_hashbucket *head2; struct inet_bind2_bucket *tb2; bool reuseport_cb_ok; 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(); head2 = inet_bhash2_addr_any_hashbucket(sk, net, port); spin_lock(&head2->lock); inet_bind_bucket_for_each(tb2, &head2->chain) if (inet_bind2_bucket_match_addr_any(tb2, net, port, l3mdev, sk)) break; if (tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok, reuseport_ok)) { spin_unlock(&head2->lock); return true; } spin_unlock(&head2->lock); return false; } /* * Find an open port number for the socket. Returns with the * inet_bind_hashbucket locks held if successful. */ static struct inet_bind_hashbucket * inet_csk_find_open_port(const struct sock *sk, struct inet_bind_bucket **tb_ret, struct inet_bind2_bucket **tb2_ret, struct inet_bind_hashbucket **head2_ret, int *port_ret) { struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk); int i, low, high, attempt_half, port, l3mdev; struct inet_bind_hashbucket *head, *head2; struct net *net = sock_net(sk); struct inet_bind2_bucket *tb2; struct inet_bind_bucket *tb; u32 remaining, offset; bool relax = false; 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 = get_random_u32_below(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); if (inet_use_bhash2_on_bind(sk)) { if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, relax, false)) goto next_port; } head2 = inet_bhashfn_portaddr(hinfo, sk, net, port); spin_lock(&head2->lock); tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk); inet_bind_bucket_for_each(tb, &head->chain) if (inet_bind_bucket_match(tb, net, port, l3mdev)) { if (!inet_csk_bind_conflict(sk, tb, tb2, relax, false)) goto success; spin_unlock(&head2->lock); 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; *tb2_ret = tb2; *head2_ret = head2; 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) { struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk); bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN; bool found_port = false, check_bind_conflict = true; bool bhash_created = false, bhash2_created = false; int ret = -EADDRINUSE, port = snum, l3mdev; struct inet_bind_hashbucket *head, *head2; struct inet_bind2_bucket *tb2 = NULL; struct inet_bind_bucket *tb = NULL; bool head2_lock_acquired = false; struct net *net = sock_net(sk); l3mdev = inet_sk_bound_l3mdev(sk); if (!port) { head = inet_csk_find_open_port(sk, &tb, &tb2, &head2, &port); if (!head) return ret; head2_lock_acquired = true; if (tb && tb2) goto success; found_port = true; } else { head = &hinfo->bhash[inet_bhashfn(net, port, hinfo->bhash_size)]; spin_lock_bh(&head->lock); inet_bind_bucket_for_each(tb, &head->chain) if (inet_bind_bucket_match(tb, net, port, l3mdev)) break; } if (!tb) { tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, net, head, port, l3mdev); if (!tb) goto fail_unlock; bhash_created = true; } if (!found_port) { if (!hlist_empty(&tb->owners)) { if (sk->sk_reuse == SK_FORCE_REUSE || (tb->fastreuse > 0 && reuse) || sk_reuseport_match(tb, sk)) check_bind_conflict = false; } if (check_bind_conflict && inet_use_bhash2_on_bind(sk)) { if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, true, true)) goto fail_unlock; } head2 = inet_bhashfn_portaddr(hinfo, sk, net, port); spin_lock(&head2->lock); head2_lock_acquired = true; tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk); } if (!tb2) { tb2 = inet_bind2_bucket_create(hinfo->bind2_bucket_cachep, net, head2, port, l3mdev, sk); if (!tb2) goto fail_unlock; bhash2_created = true; } if (!found_port && check_bind_conflict) { if (inet_csk_bind_conflict(sk, tb, tb2, true, true)) goto fail_unlock; } success: inet_csk_update_fastreuse(tb, sk); if (!inet_csk(sk)->icsk_bind_hash) inet_bind_hash(sk, tb, tb2, port); WARN_ON(inet_csk(sk)->icsk_bind_hash != tb); WARN_ON(inet_csk(sk)->icsk_bind2_hash != tb2); ret = 0; fail_unlock: if (ret) { if (bhash_created) inet_bind_bucket_destroy(hinfo->bind_bucket_cachep, tb); if (bhash2_created) inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep, tb2); } if (head2_lock_acquired) spin_unlock(&head2->lock); 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 sock *sk = req_to_sk(req); bool found = false; if (sk_hashed(sk)) { struct inet_hashinfo *hashinfo = tcp_or_dccp_get_hashinfo(sk); spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash); spin_lock(lock); found = __sk_nulls_del_node_init_rcu(sk); 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 ? : 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. */ 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)) { if (req->num_timeout++ == 0) atomic_dec(&queue->young); mod_timer(&req->rsk_timer, jiffies + reqsk_timeout(req, TCP_RTO_MAX)); 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; newicsk->icsk_bind2_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); int inet_csk_listen_start(struct sock *sk) { struct inet_connection_sock *icsk = inet_csk(sk); struct inet_sock *inet = inet_sk(sk); int err; reqsk_queue_alloc(&icsk->icsk_accept_queue); sk->sk_ack_backlog = 0; inet_csk_delack_init(sk); if (sk->sk_txrehash == SOCK_TXREHASH_DEFAULT) sk->sk_txrehash = READ_ONCE(sock_net(sk)->core.sysctl_txrehash); /* 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); err = sk->sk_prot->get_port(sk, inet->inet_num); if (!err) { 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(req->rsk_listener, req); reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req); if (sk != req->rsk_listener) { /* another listening sk has been selected, * migrate the req to it. */ struct request_sock *nreq; /* hold a refcnt for the nreq->rsk_listener * which is assigned in inet_reqsk_clone() */ sock_hold(sk); nreq = inet_reqsk_clone(req, sk); if (!nreq) { inet_child_forget(sk, req, child); goto child_put; } refcount_set(&nreq->rsk_refcnt, 1); if (inet_csk_reqsk_queue_add(sk, nreq, child)) { __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS); reqsk_migrate_reset(req); reqsk_put(req); return child; } __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE); reqsk_migrate_reset(nreq); __reqsk_free(nreq); } else if (inet_csk_reqsk_queue_add(sk, req, child)) { return child; } } /* Too bad, another child took ownership of the request, undo. */ child_put: 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, *nsk; struct request_sock *nreq; local_bh_disable(); bh_lock_sock(child); WARN_ON(sock_owned_by_user(child)); sock_hold(child); nsk = reuseport_migrate_sock(sk, child, NULL); if (nsk) { nreq = inet_reqsk_clone(req, nsk); if (nreq) { refcount_set(&nreq->rsk_refcnt, 1); if (inet_csk_reqsk_queue_add(nsk, nreq, child)) { __NET_INC_STATS(sock_net(nsk), LINUX_MIB_TCPMIGRATEREQSUCCESS); reqsk_migrate_reset(req); } else { __NET_INC_STATS(sock_net(nsk), LINUX_MIB_TCPMIGRATEREQFAILURE); reqsk_migrate_reset(nreq); __reqsk_free(nreq); } /* inet_csk_reqsk_queue_add() has already * called inet_child_forget() on failure case. */ goto skip_child_forget; } } inet_child_forget(sk, req, child); skip_child_forget: 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);