tcp: add a drop_reason pointer to tcp_check_req()

We want to add new drop reasons for packets dropped in 3WHS in the
following patches.

tcp_rcv_state_process() has to set reason to TCP_FASTOPEN,
because tcp_check_req() will conditionally overwrite the drop_reason.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250301201424.2046477-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/tcp.h b/include/net/tcp.h
index f9b9377..a9bc959 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -392,7 +392,7 @@ enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
                                              u32 *tw_isn);
 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
                           struct request_sock *req, bool fastopen,
-                          bool *lost_race);
+                          bool *lost_race, enum skb_drop_reason *drop_reason);
 enum skb_drop_reason tcp_child_process(struct sock *parent, struct sock *child,
                                       struct sk_buff *skb);
 void tcp_enter_loss(struct sock *sk);

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index d22ad55..4e22123 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -6812,10 +6812,9 @@ tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
                WARN_ON_ONCE(sk->sk_state != TCP_SYN_RECV &&
                    sk->sk_state != TCP_FIN_WAIT1);
 
-               if (!tcp_check_req(sk, skb, req, true, &req_stolen)) {
-                       SKB_DR_SET(reason, TCP_FASTOPEN);
+               SKB_DR_SET(reason, TCP_FASTOPEN);
+               if (!tcp_check_req(sk, skb, req, true, &req_stolen, &reason))
                        goto discard;
-               }
        }
 
        if (!th->ack && !th->rst && !th->syn) {

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 7900855..218f01a 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2265,7 +2265,8 @@ lookup:
                        th = (const struct tcphdr *)skb->data;
                        iph = ip_hdr(skb);
                        tcp_v4_fill_cb(skb, iph, th);
-                       nsk = tcp_check_req(sk, skb, req, false, &req_stolen);
+                       nsk = tcp_check_req(sk, skb, req, false, &req_stolen,
+                                           &drop_reason);
                } else {
                        drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
                }

diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 29b54ad..46c86c4 100644 (file)
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -657,7 +657,8 @@ EXPORT_SYMBOL(tcp_create_openreq_child);
 
 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
                           struct request_sock *req,
-                          bool fastopen, bool *req_stolen)
+                          bool fastopen, bool *req_stolen,
+                          enum skb_drop_reason *drop_reason)
 {
        struct tcp_options_received tmp_opt;
        struct sock *child;

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index a806082..d01088a 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1828,7 +1828,8 @@ lookup:
                        th = (const struct tcphdr *)skb->data;
                        hdr = ipv6_hdr(skb);
                        tcp_v6_fill_cb(skb, hdr, th);
-                       nsk = tcp_check_req(sk, skb, req, false, &req_stolen);
+                       nsk = tcp_check_req(sk, skb, req, false, &req_stolen,
+                                           &drop_reason);
                } else {
                        drop_reason = SKB_DROP_REASON_SOCKET_FILTER;
                }