2 files changed, 28 insertions, 5 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 66d85a80a1ec..1a7adb411647 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -342,6 +342,10 @@ struct tcp_timewait_sock {
         u32                       tw_rcv_wnd;
         u32                       tw_ts_offset;
         u32                       tw_ts_recent;
+
+        /* The time we sent the last out-of-window ACK: */
+        u32                       tw_last_oow_ack_time;
+
         long                      tw_ts_recent_stamp;
 #ifdef CONFIG_TCP_MD5SIG
         struct tcp_md5sig_key     *tw_md5_key;
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 98a840561ec8..dd11ac7798c6 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -58,6 +58,25 @@ static bool tcp_in_window(u32 seq, u32 end_seq, u32 s_win, u32 e_win)
         return seq == e_win && seq == end_seq;
 }
 
+static enum tcp_tw_status
+tcp_timewait_check_oow_rate_limit(struct inet_timewait_sock *tw,
+                                  const struct sk_buff *skb, int mib_idx)
+{
+        struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw);
+
+        if (!tcp_oow_rate_limited(twsk_net(tw), skb, mib_idx,
+                                  &tcptw->tw_last_oow_ack_time)) {
+                /* Send ACK. Note, we do not put the bucket,
+                 * it will be released by caller.
+                 */
+                return TCP_TW_ACK;
+        }
+
+        /* We are rate-limiting, so just release the tw sock and drop skb. */
+        inet_twsk_put(tw);
+        return TCP_TW_SUCCESS;
+}
+
 /*
  * * Main purpose of TIME-WAIT state is to close connection gracefully,
  *   when one of ends sits in LAST-ACK or CLOSING retransmitting FIN
@@ -116,7 +135,8 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
                     !tcp_in_window(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq,
                                    tcptw->tw_rcv_nxt,
                                    tcptw->tw_rcv_nxt + tcptw->tw_rcv_wnd))
-                        return TCP_TW_ACK;
+                        return tcp_timewait_check_oow_rate_limit(
+                                tw, skb, LINUX_MIB_TCPACKSKIPPEDFINWAIT2);
 
                 if (th->rst)
                         goto kill;
@@ -250,10 +270,8 @@ kill:
                         inet_twsk_schedule(tw, &tcp_death_row, TCP_TIMEWAIT_LEN,
                                            TCP_TIMEWAIT_LEN);
 
-                /* Send ACK. Note, we do not put the bucket,
-                 * it will be released by caller.
-                 */
-                return TCP_TW_ACK;
+                return tcp_timewait_check_oow_rate_limit(
+                        tw, skb, LINUX_MIB_TCPACKSKIPPEDTIMEWAIT);
         }
         inet_twsk_put(tw);
         return TCP_TW_SUCCESS;
@@ -289,6 +307,7 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
                 tcptw->tw_ts_recent     = tp->rx_opt.ts_recent;
                 tcptw->tw_ts_recent_stamp = tp->rx_opt.ts_recent_stamp;
                 tcptw->tw_ts_offset     = tp->tsoffset;
+                tcptw->tw_last_oow_ack_time = 0;
 
 #if IS_ENABLED(CONFIG_IPV6)
                 if (tw->tw_family == PF_INET6) {