tcp: Don't initialise tp->tsoffset in tcp_get_cookie_sock().

When we create a full socket from SYN Cookie, we initialise
tcp_sk(sk)->tsoffset redundantly in tcp_get_cookie_sock() as
the field is inherited from tcp_rsk(req)->ts_off.

  cookie_v[46]_check
  |- treq->ts_off = 0
  `- tcp_get_cookie_sock
     |- tcp_v[46]_syn_recv_sock
     |  `- tcp_create_openreq_child
     |	   `- newtp->tsoffset = treq->ts_off
     `- tcp_sk(child)->tsoffset = tsoff

Let's initialise tcp_rsk(req)->ts_off with the correct offset
and remove the second initialisation of tcp_sk(sk)->tsoffset.

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231129022924.96156-6-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 2b2c79c7bbcd5831dec84318708e659faef26556..cc7143a781da8650c8590a39688be67d1a1bdc38 100644 (file)
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -490,7 +490,7 @@ void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
 /* From syncookies.c */
 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
                                 struct request_sock *req,
-                                struct dst_entry *dst, u32 tsoff);
+                                struct dst_entry *dst);
 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th);
 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
 struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index c08428d63d11dda95333f9aa1e9c46e0d210e3df..de051eb08db85184e64ceb145921ce37a03411c8 100644 (file)
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -204,7 +204,7 @@ EXPORT_SYMBOL_GPL(__cookie_v4_check);
 
 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
                                 struct request_sock *req,
-                                struct dst_entry *dst, u32 tsoff)
+                                struct dst_entry *dst)
 {
        struct inet_connection_sock *icsk = inet_csk(sk);
        struct sock *child;
@@ -214,7 +214,6 @@ struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
                                                 NULL, &own_req);
        if (child) {
                refcount_set(&req->rsk_refcnt, 1);
-               tcp_sk(child)->tsoffset = tsoff;
                sock_rps_save_rxhash(child, skb);
 
                if (rsk_drop_req(req)) {
@@ -386,7 +385,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
        treq = tcp_rsk(req);
        treq->rcv_isn           = ntohl(th->seq) - 1;
        treq->snt_isn           = ntohl(th->ack_seq) - 1;
-       treq->ts_off            = 0;
+       treq->ts_off            = tsoff;
        treq->txhash            = net_tx_rndhash();
        req->mss                = mss;
        ireq->ir_num            = ntohs(th->dest);
@@ -452,7 +451,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
        ireq->rcv_wscale  = rcv_wscale;
        ireq->ecn_ok = cookie_ecn_ok(&tcp_opt, net, &rt->dst);
 
-       ret = tcp_get_cookie_sock(sk, skb, req, &rt->dst, tsoff);
+       ret = tcp_get_cookie_sock(sk, skb, req, &rt->dst);
        /* ip_queue_xmit() depends on our flow being setup
         * Normal sockets get it right from inet_csk_route_child_sock()
         */

diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 4cd26c481168332f31be2ed409c24e7ad8ce46cc..18c2e3c1677b572c4445935ebe69031b74e6bf1a 100644 (file)
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -215,7 +215,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
        treq->snt_synack        = 0;
        treq->rcv_isn = ntohl(th->seq) - 1;
        treq->snt_isn = ntohl(th->ack_seq) - 1;
-       treq->ts_off = 0;
+       treq->ts_off = tsoff;
        treq->txhash = net_tx_rndhash();
 
        l3index = l3mdev_master_ifindex_by_index(net, ireq->ir_iif);
@@ -264,7 +264,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb)
        ireq->rcv_wscale = rcv_wscale;
        ireq->ecn_ok = cookie_ecn_ok(&tcp_opt, net, dst);
 
-       ret = tcp_get_cookie_sock(sk, skb, req, dst, tsoff);
+       ret = tcp_get_cookie_sock(sk, skb, req, dst);
 out:
        return ret;
 out_free: