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Diffstat (limited to 'net/ipv4/tcp_input.c')
-rw-r--r--net/ipv4/tcp_input.c111
1 files changed, 80 insertions, 31 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 731d3045b50a..077d9abdfcf5 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -2252,7 +2252,7 @@ static bool tcp_skb_spurious_retrans(const struct tcp_sock *tp,
*/
static inline bool tcp_packet_delayed(const struct tcp_sock *tp)
{
- return !tp->retrans_stamp ||
+ return tp->retrans_stamp &&
tcp_tsopt_ecr_before(tp, tp->retrans_stamp);
}
@@ -3521,7 +3521,7 @@ static void tcp_xmit_recovery(struct sock *sk, int rexmit)
{
struct tcp_sock *tp = tcp_sk(sk);
- if (rexmit == REXMIT_NONE)
+ if (rexmit == REXMIT_NONE || sk->sk_state == TCP_SYN_SENT)
return;
if (unlikely(rexmit == 2)) {
@@ -5647,6 +5647,32 @@ discard:
}
EXPORT_SYMBOL(tcp_rcv_established);
+void tcp_init_transfer(struct sock *sk, int bpf_op)
+{
+ struct inet_connection_sock *icsk = inet_csk(sk);
+ struct tcp_sock *tp = tcp_sk(sk);
+
+ tcp_mtup_init(sk);
+ icsk->icsk_af_ops->rebuild_header(sk);
+ tcp_init_metrics(sk);
+
+ /* Initialize the congestion window to start the transfer.
+ * Cut cwnd down to 1 per RFC5681 if SYN or SYN-ACK has been
+ * retransmitted. In light of RFC6298 more aggressive 1sec
+ * initRTO, we only reset cwnd when more than 1 SYN/SYN-ACK
+ * retransmission has occurred.
+ */
+ if (tp->total_retrans > 1 && tp->undo_marker)
+ tp->snd_cwnd = 1;
+ else
+ tp->snd_cwnd = tcp_init_cwnd(tp, __sk_dst_get(sk));
+ tp->snd_cwnd_stamp = tcp_jiffies32;
+
+ tcp_call_bpf(sk, bpf_op, 0, NULL);
+ tcp_init_congestion_control(sk);
+ tcp_init_buffer_space(sk);
+}
+
void tcp_finish_connect(struct sock *sk, struct sk_buff *skb)
{
struct tcp_sock *tp = tcp_sk(sk);
@@ -5748,6 +5774,21 @@ static void smc_check_reset_syn(struct tcp_sock *tp)
#endif
}
+static void tcp_try_undo_spurious_syn(struct sock *sk)
+{
+ struct tcp_sock *tp = tcp_sk(sk);
+ u32 syn_stamp;
+
+ /* undo_marker is set when SYN or SYNACK times out. The timeout is
+ * spurious if the ACK's timestamp option echo value matches the
+ * original SYN timestamp.
+ */
+ syn_stamp = tp->retrans_stamp;
+ if (tp->undo_marker && syn_stamp && tp->rx_opt.saw_tstamp &&
+ syn_stamp == tp->rx_opt.rcv_tsecr)
+ tp->undo_marker = 0;
+}
+
static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
const struct tcphdr *th)
{
@@ -5815,6 +5856,7 @@ static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
tcp_ecn_rcv_synack(tp, th);
tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
+ tcp_try_undo_spurious_syn(sk);
tcp_ack(sk, skb, FLAG_SLOWPATH);
/* Ok.. it's good. Set up sequence numbers and
@@ -5973,6 +6015,27 @@ reset_and_undo:
return 1;
}
+static void tcp_rcv_synrecv_state_fastopen(struct sock *sk)
+{
+ tcp_try_undo_loss(sk, false);
+ inet_csk(sk)->icsk_retransmits = 0;
+
+ /* Once we leave TCP_SYN_RECV or TCP_FIN_WAIT_1,
+ * we no longer need req so release it.
+ */
+ reqsk_fastopen_remove(sk, tcp_sk(sk)->fastopen_rsk, false);
+
+ /* Re-arm the timer because data may have been sent out.
+ * This is similar to the regular data transmission case
+ * when new data has just been ack'ed.
+ *
+ * (TFO) - we could try to be more aggressive and
+ * retransmitting any data sooner based on when they
+ * are sent out.
+ */
+ tcp_rearm_rto(sk);
+}
+
/*
* This function implements the receiving procedure of RFC 793 for
* all states except ESTABLISHED and TIME_WAIT.
@@ -6069,22 +6132,11 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
if (!tp->srtt_us)
tcp_synack_rtt_meas(sk, req);
- /* Once we leave TCP_SYN_RECV, we no longer need req
- * so release it.
- */
if (req) {
- inet_csk(sk)->icsk_retransmits = 0;
- reqsk_fastopen_remove(sk, req, false);
- /* Re-arm the timer because data may have been sent out.
- * This is similar to the regular data transmission case
- * when new data has just been ack'ed.
- *
- * (TFO) - we could try to be more aggressive and
- * retransmitting any data sooner based on when they
- * are sent out.
- */
- tcp_rearm_rto(sk);
+ tcp_rcv_synrecv_state_fastopen(sk);
} else {
+ tcp_try_undo_spurious_syn(sk);
+ tp->retrans_stamp = 0;
tcp_init_transfer(sk, BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB);
tp->copied_seq = tp->rcv_nxt;
}
@@ -6119,16 +6171,9 @@ int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
case TCP_FIN_WAIT1: {
int tmo;
- /* If we enter the TCP_FIN_WAIT1 state and we are a
- * Fast Open socket and this is the first acceptable
- * ACK we have received, this would have acknowledged
- * our SYNACK so stop the SYNACK timer.
- */
- if (req) {
- /* We no longer need the request sock. */
- reqsk_fastopen_remove(sk, req, false);
- tcp_rearm_rto(sk);
- }
+ if (req)
+ tcp_rcv_synrecv_state_fastopen(sk);
+
if (tp->snd_una != tp->write_seq)
break;
@@ -6263,6 +6308,11 @@ static inline void pr_drop_req(struct request_sock *req, __u16 port, int family)
* congestion control: Linux DCTCP asserts ECT on all packets,
* including SYN, which is most optimal solution; however,
* others, such as FreeBSD do not.
+ *
+ * Exception: At least one of the reserved bits of the TCP header (th->res1) is
+ * set, indicating the use of a future TCP extension (such as AccECN). See
+ * RFC8311 ยง4.3 which updates RFC3168 to allow the development of such
+ * extensions.
*/
static void tcp_ecn_create_request(struct request_sock *req,
const struct sk_buff *skb,
@@ -6282,7 +6332,7 @@ static void tcp_ecn_create_request(struct request_sock *req,
ecn_ok_dst = dst_feature(dst, DST_FEATURE_ECN_MASK);
ecn_ok = net->ipv4.sysctl_tcp_ecn || ecn_ok_dst;
- if ((!ect && ecn_ok) || tcp_ca_needs_ecn(listen_sk) ||
+ if (((!ect || th->res1) && ecn_ok) || tcp_ca_needs_ecn(listen_sk) ||
(ecn_ok_dst & DST_FEATURE_ECN_CA) ||
tcp_bpf_ca_needs_ecn((struct sock *)req))
inet_rsk(req)->ecn_ok = 1;
@@ -6298,7 +6348,7 @@ static void tcp_openreq_init(struct request_sock *req,
req->cookie_ts = 0;
tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
- tcp_rsk(req)->snt_synack = tcp_clock_us();
+ tcp_rsk(req)->snt_synack = 0;
tcp_rsk(req)->last_oow_ack_time = 0;
req->mss = rx_opt->mss_clamp;
req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
@@ -6502,8 +6552,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
reqsk_fastopen_remove(fastopen_sk, req, false);
bh_unlock_sock(fastopen_sk);
sock_put(fastopen_sk);
- reqsk_put(req);
- goto drop;
+ goto drop_and_free;
}
sk->sk_data_ready(sk);
bh_unlock_sock(fastopen_sk);
@@ -6527,7 +6576,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
drop_and_release:
dst_release(dst);
drop_and_free:
- reqsk_free(req);
+ __reqsk_free(req);
drop:
tcp_listendrop(sk);
return 0;