return 0;
}
EXPORT_SYMBOL(tcp_rcv_state_process);
+
+static inline void pr_drop_req(struct request_sock *req, __u16 port, int family)
+{
+ struct inet_request_sock *ireq = inet_rsk(req);
+
+ if (family == AF_INET)
+ LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("drop open request from %pI4/%u\n"),
+ &ireq->ir_rmt_addr, port);
+ else
+ LIMIT_NETDEBUG(KERN_DEBUG pr_fmt("drop open request from %pI6/%u\n"),
+ &ireq->ir_v6_rmt_addr, port);
+}
+
+int tcp_conn_request(struct request_sock_ops *rsk_ops,
+ const struct tcp_request_sock_ops *af_ops,
+ struct sock *sk, struct sk_buff *skb)
+{
+ struct tcp_options_received tmp_opt;
+ struct request_sock *req;
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct dst_entry *dst = NULL;
+ __u32 isn = TCP_SKB_CB(skb)->when;
+ bool want_cookie = false, fastopen;
+ struct flowi fl;
+ struct tcp_fastopen_cookie foc = { .len = -1 };
+ int err;
+
+
+ /* TW buckets are converted to open requests without
+ * limitations, they conserve resources and peer is
+ * evidently real one.
+ */
+ if ((sysctl_tcp_syncookies == 2 ||
+ inet_csk_reqsk_queue_is_full(sk)) && !isn) {
+ want_cookie = tcp_syn_flood_action(sk, skb, rsk_ops->slab_name);
+ if (!want_cookie)
+ goto drop;
+ }
+
+
+ /* Accept backlog is full. If we have already queued enough
+ * of warm entries in syn queue, drop request. It is better than
+ * clogging syn queue with openreqs with exponentially increasing
+ * timeout.
+ */
+ if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENOVERFLOWS);
+ goto drop;
+ }
+
+ req = inet_reqsk_alloc(rsk_ops);
+ if (!req)
+ goto drop;
+
+ tcp_rsk(req)->af_specific = af_ops;
+
+ tcp_clear_options(&tmp_opt);
+ tmp_opt.mss_clamp = af_ops->mss_clamp;
+ tmp_opt.user_mss = tp->rx_opt.user_mss;
+ tcp_parse_options(skb, &tmp_opt, 0, want_cookie ? NULL : &foc);
+
+ if (want_cookie && !tmp_opt.saw_tstamp)
+ tcp_clear_options(&tmp_opt);
+
+ tmp_opt.tstamp_ok = tmp_opt.saw_tstamp;
+ tcp_openreq_init(req, &tmp_opt, skb, sk);
+
+ af_ops->init_req(req, sk, skb);
+
+ if (security_inet_conn_request(sk, skb, req))
+ goto drop_and_free;
+
+ if (!want_cookie || tmp_opt.tstamp_ok)
+ TCP_ECN_create_request(req, skb, sock_net(sk));
+
+ if (want_cookie) {
+ isn = cookie_init_sequence(af_ops, sk, skb, &req->mss);
+ req->cookie_ts = tmp_opt.tstamp_ok;
+ } else if (!isn) {
+ /* VJ's idea. We save last timestamp seen
+ * from the destination in peer table, when entering
+ * state TIME-WAIT, and check against it before
+ * accepting new connection request.
+ *
+ * If "isn" is not zero, this request hit alive
+ * timewait bucket, so that all the necessary checks
+ * are made in the function processing timewait state.
+ */
+ if (tmp_opt.saw_tstamp && tcp_death_row.sysctl_tw_recycle) {
+ bool strict;
+
+ dst = af_ops->route_req(sk, &fl, req, &strict);
+ if (dst && strict &&
+ !tcp_peer_is_proven(req, dst, true)) {
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSPASSIVEREJECTED);
+ goto drop_and_release;
+ }
+ }
+ /* Kill the following clause, if you dislike this way. */
+ else if (!sysctl_tcp_syncookies &&
+ (sysctl_max_syn_backlog - inet_csk_reqsk_queue_len(sk) <
+ (sysctl_max_syn_backlog >> 2)) &&
+ !tcp_peer_is_proven(req, dst, false)) {
+ /* Without syncookies last quarter of
+ * backlog is filled with destinations,
+ * proven to be alive.
+ * It means that we continue to communicate
+ * to destinations, already remembered
+ * to the moment of synflood.
+ */
+ pr_drop_req(req, ntohs(tcp_hdr(skb)->source),
+ rsk_ops->family);
+ goto drop_and_release;
+ }
+
+ isn = af_ops->init_seq(skb);
+ }
+ if (!dst) {
+ dst = af_ops->route_req(sk, &fl, req, NULL);
+ if (!dst)
+ goto drop_and_free;
+ }
+
+ tcp_rsk(req)->snt_isn = isn;
+ tcp_openreq_init_rwin(req, sk, dst);
+ fastopen = !want_cookie &&
+ tcp_try_fastopen(sk, skb, req, &foc, dst);
+ err = af_ops->send_synack(sk, dst, &fl, req,
+ skb_get_queue_mapping(skb), &foc);
+ if (!fastopen) {
+ if (err || want_cookie)
+ goto drop_and_free;
+
+ tcp_rsk(req)->listener = NULL;
+ af_ops->queue_hash_add(sk, req, TCP_TIMEOUT_INIT);
+ }
+
+ return 0;
+
+drop_and_release:
+ dst_release(dst);
+drop_and_free:
+ reqsk_free(req);
+drop:
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_LISTENDROPS);
+ return 0;
+}
+EXPORT_SYMBOL(tcp_conn_request);
OSDN Git Service
