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Message-ID: <20240215210922.19969-1-kuniyu@amazon.com>
Date: Thu, 15 Feb 2024 13:09:22 -0800
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: <kerneljasonxing@...il.com>
CC: <davem@...emloft.net>, <dsahern@...nel.org>, <edumazet@...gle.com>,
<kernelxing@...cent.com>, <kuba@...nel.org>, <kuniyu@...zon.com>,
<netdev@...r.kernel.org>, <pabeni@...hat.com>
Subject: [PATCH net-next v5 03/11] tcp: use drop reasons in cookie check for ipv4
From: Jason Xing <kerneljasonxing@...il.com>
Date: Thu, 15 Feb 2024 09:20:19 +0800
> From: Jason Xing <kernelxing@...cent.com>
>
> Now it's time to use the prepared definitions to refine this part.
> Four reasons used might enough for now, I think.
>
> Signed-off-by: Jason Xing <kernelxing@...cent.com>
> --
> v5:
> Link: https://lore.kernel.org/netdev/CANn89i+iELpsoea6+C-08m6+=JkneEEM=nAj-28eNtcOCkwQjw@mail.gmail.com/
> Link: https://lore.kernel.org/netdev/632c6fd4-e060-4b8e-a80e-5d545a6c6b6c@kernel.org/
> 1. Use SKB_DROP_REASON_IP_OUTNOROUTES instead of introducing a new one (Eric, David)
> 2. Reuse SKB_DROP_REASON_NOMEM to handle failure of request socket allocation (Eric)
> 3. Reuse NO_SOCKET instead of introducing COOKIE_NOCHILD
> ---
> net/ipv4/syncookies.c | 18 +++++++++++++-----
> 1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
> index 38f331da6677..aeb61c880fbd 100644
> --- a/net/ipv4/syncookies.c
> +++ b/net/ipv4/syncookies.c
> @@ -421,8 +421,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
> if (IS_ERR(req))
> goto out;
> }
> - if (!req)
> + if (!req) {
> + SKB_DR_SET(reason, NOMEM);
NOMEM is not appropriate when mptcp_subflow_init_cookie_req() fails.
> goto out_drop;
> + }
>
> ireq = inet_rsk(req);
>
> @@ -434,8 +436,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
> */
> RCU_INIT_POINTER(ireq->ireq_opt, tcp_v4_save_options(net, skb));
>
> - if (security_inet_conn_request(sk, skb, req))
> + if (security_inet_conn_request(sk, skb, req)) {
> + SKB_DR_SET(reason, SECURITY_HOOK);
> goto out_free;
> + }
>
> tcp_ao_syncookie(sk, skb, req, AF_INET);
>
> @@ -452,8 +456,10 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
> ireq->ir_loc_addr, th->source, th->dest, sk->sk_uid);
> security_req_classify_flow(req, flowi4_to_flowi_common(&fl4));
> rt = ip_route_output_key(net, &fl4);
> - if (IS_ERR(rt))
> + if (IS_ERR(rt)) {
> + SKB_DR_SET(reason, IP_OUTNOROUTES);
> goto out_free;
> + }
>
> /* Try to redo what tcp_v4_send_synack did. */
> req->rsk_window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW);
> @@ -476,10 +482,12 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
> /* ip_queue_xmit() depends on our flow being setup
> * Normal sockets get it right from inet_csk_route_child_sock()
> */
> - if (ret)
> + if (ret) {
> inet_sk(ret)->cork.fl.u.ip4 = fl4;
> - else
> + } else {
> + SKB_DR_SET(reason, NO_SOCKET);
This also seems wrong to me.
e.g. syn_recv_sock() could fail with sk_acceptq_is_full(sk),
then the listener is actually found.
> goto out_drop;
> + }
> out:
> return ret;
> out_free:
> --
> 2.37.3
>
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