tcp: move fastopen functions to tcp_fastopen.c
Move common TFO functions that will be used by both v4 and v6
to tcp_fastopen.c. Create a helper tcp_fastopen_queue_check().
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Daniel Lee <longinus00@gmail.com>
Signed-off-by: Jerry Chu <hkchu@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index f195d93..0606c91 100644
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -94,3 +94,193 @@
}
rcu_read_unlock();
}
+
+int tcp_fastopen_create_child(struct sock *sk,
+ struct sk_buff *skb,
+ struct sk_buff *skb_synack,
+ struct request_sock *req)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
+ const struct inet_request_sock *ireq = inet_rsk(req);
+ struct sock *child;
+ int err;
+
+ req->num_retrans = 0;
+ req->num_timeout = 0;
+ req->sk = NULL;
+
+ child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
+ if (child == NULL) {
+ NET_INC_STATS_BH(sock_net(sk),
+ LINUX_MIB_TCPFASTOPENPASSIVEFAIL);
+ kfree_skb(skb_synack);
+ return -1;
+ }
+ err = ip_build_and_send_pkt(skb_synack, sk, ireq->ir_loc_addr,
+ ireq->ir_rmt_addr, ireq->opt);
+ err = net_xmit_eval(err);
+ if (!err)
+ tcp_rsk(req)->snt_synack = tcp_time_stamp;
+ /* XXX (TFO) - is it ok to ignore error and continue? */
+
+ spin_lock(&queue->fastopenq->lock);
+ queue->fastopenq->qlen++;
+ spin_unlock(&queue->fastopenq->lock);
+
+ /* Initialize the child socket. Have to fix some values to take
+ * into account the child is a Fast Open socket and is created
+ * only out of the bits carried in the SYN packet.
+ */
+ tp = tcp_sk(child);
+
+ tp->fastopen_rsk = req;
+ /* Do a hold on the listner sk so that if the listener is being
+ * closed, the child that has been accepted can live on and still
+ * access listen_lock.
+ */
+ sock_hold(sk);
+ tcp_rsk(req)->listener = sk;
+
+ /* RFC1323: The window in SYN & SYN/ACK segments is never
+ * scaled. So correct it appropriately.
+ */
+ tp->snd_wnd = ntohs(tcp_hdr(skb)->window);
+
+ /* Activate the retrans timer so that SYNACK can be retransmitted.
+ * The request socket is not added to the SYN table of the parent
+ * because it's been added to the accept queue directly.
+ */
+ inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS,
+ TCP_TIMEOUT_INIT, TCP_RTO_MAX);
+
+ /* Add the child socket directly into the accept queue */
+ inet_csk_reqsk_queue_add(sk, req, child);
+
+ /* Now finish processing the fastopen child socket. */
+ inet_csk(child)->icsk_af_ops->rebuild_header(child);
+ tcp_init_congestion_control(child);
+ tcp_mtup_init(child);
+ tcp_init_metrics(child);
+ tcp_init_buffer_space(child);
+
+ /* Queue the data carried in the SYN packet. We need to first
+ * bump skb's refcnt because the caller will attempt to free it.
+ *
+ * XXX (TFO) - we honor a zero-payload TFO request for now.
+ * (Any reason not to?)
+ */
+ if (TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq + 1) {
+ /* Don't queue the skb if there is no payload in SYN.
+ * XXX (TFO) - How about SYN+FIN?
+ */
+ tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+ } else {
+ skb = skb_get(skb);
+ skb_dst_drop(skb);
+ __skb_pull(skb, tcp_hdr(skb)->doff * 4);
+ skb_set_owner_r(skb, child);
+ __skb_queue_tail(&child->sk_receive_queue, skb);
+ tp->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+ tp->syn_data_acked = 1;
+ }
+ sk->sk_data_ready(sk);
+ bh_unlock_sock(child);
+ sock_put(child);
+ WARN_ON(req->sk == NULL);
+ return 0;
+}
+EXPORT_SYMBOL(tcp_fastopen_create_child);
+
+static bool tcp_fastopen_queue_check(struct sock *sk)
+{
+ struct fastopen_queue *fastopenq;
+
+ /* Make sure the listener has enabled fastopen, and we don't
+ * exceed the max # of pending TFO requests allowed before trying
+ * to validating the cookie in order to avoid burning CPU cycles
+ * unnecessarily.
+ *
+ * XXX (TFO) - The implication of checking the max_qlen before
+ * processing a cookie request is that clients can't differentiate
+ * between qlen overflow causing Fast Open to be disabled
+ * temporarily vs a server not supporting Fast Open at all.
+ */
+ fastopenq = inet_csk(sk)->icsk_accept_queue.fastopenq;
+ if (fastopenq == NULL || fastopenq->max_qlen == 0)
+ return false;
+
+ if (fastopenq->qlen >= fastopenq->max_qlen) {
+ struct request_sock *req1;
+ spin_lock(&fastopenq->lock);
+ req1 = fastopenq->rskq_rst_head;
+ if ((req1 == NULL) || time_after(req1->expires, jiffies)) {
+ spin_unlock(&fastopenq->lock);
+ NET_INC_STATS_BH(sock_net(sk),
+ LINUX_MIB_TCPFASTOPENLISTENOVERFLOW);
+ return false;
+ }
+ fastopenq->rskq_rst_head = req1->dl_next;
+ fastopenq->qlen--;
+ spin_unlock(&fastopenq->lock);
+ reqsk_free(req1);
+ }
+ return true;
+}
+
+bool tcp_fastopen_check(struct sock *sk, struct sk_buff *skb,
+ struct request_sock *req,
+ struct tcp_fastopen_cookie *foc,
+ struct tcp_fastopen_cookie *valid_foc)
+{
+ bool skip_cookie = false;
+
+ if (likely(!fastopen_cookie_present(foc))) {
+ /* See include/net/tcp.h for the meaning of these knobs */
+ if ((sysctl_tcp_fastopen & TFO_SERVER_ALWAYS) ||
+ ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_REQD) &&
+ (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq + 1)))
+ skip_cookie = true; /* no cookie to validate */
+ else
+ return false;
+ }
+ /* A FO option is present; bump the counter. */
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPFASTOPENPASSIVE);
+
+ if ((sysctl_tcp_fastopen & TFO_SERVER_ENABLE) == 0 ||
+ !tcp_fastopen_queue_check(sk))
+ return false;
+
+ if (skip_cookie) {
+ tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+ return true;
+ }
+
+ if (foc->len == TCP_FASTOPEN_COOKIE_SIZE) {
+ if ((sysctl_tcp_fastopen & TFO_SERVER_COOKIE_NOT_CHKED) == 0) {
+ tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
+ ip_hdr(skb)->daddr, valid_foc);
+ if ((valid_foc->len != TCP_FASTOPEN_COOKIE_SIZE) ||
+ memcmp(&foc->val[0], &valid_foc->val[0],
+ TCP_FASTOPEN_COOKIE_SIZE) != 0)
+ return false;
+ valid_foc->len = -1;
+ }
+ /* Acknowledge the data received from the peer. */
+ tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->end_seq;
+ return true;
+ } else if (foc->len == 0) { /* Client requesting a cookie */
+ tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
+ ip_hdr(skb)->daddr, valid_foc);
+ NET_INC_STATS_BH(sock_net(sk),
+ LINUX_MIB_TCPFASTOPENCOOKIEREQD);
+ } else {
+ /* Client sent a cookie with wrong size. Treat it
+ * the same as invalid and return a valid one.
+ */
+ tcp_fastopen_cookie_gen(ip_hdr(skb)->saddr,
+ ip_hdr(skb)->daddr, valid_foc);
+ }
+ return false;
+}
+EXPORT_SYMBOL(tcp_fastopen_check);