Commit efce3d1f authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by Jakub Kicinski
Browse files

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: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Reviewed-by: default avatarEric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231129022924.96156-6-kuniyu@amazon.com


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 7577bc82

include/net/tcp.h

+1 −1
Original line number Diff line number Diff line
@@ -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,

net/ipv4/syncookies.c

+3 −4
Original line number Diff line number Diff line
@@ -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()

	 */

net/ipv6/syncookies.c

+2 −2
Original line number Diff line number Diff line
@@ -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: