From: Martin KaFai Lau <martin.lau@linux.dev>
To: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: Kuniyuki Iwashima <kuni1840@gmail.com>,
bpf@vger.kernel.org, netdev@vger.kernel.org,
Eric Dumazet <edumazet@google.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>
Subject: Re: [PATCH v4 bpf-next 1/3] bpf: tcp: Handle BPF SYN Cookie in cookie_v[46]_check().
Date: Tue, 5 Dec 2023 16:19:20 -0800 [thread overview]
Message-ID: <8bd1d595-4bb3-44d1-a9c3-2d9c0c960bcb@linux.dev> (raw)
In-Reply-To: <20231205013420.88067-2-kuniyu@amazon.com>
On 12/4/23 5:34 PM, Kuniyuki Iwashima wrote:
> diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
> index 61f1c96cfe63..0f9c3aed2014 100644
> --- a/net/ipv4/syncookies.c
> +++ b/net/ipv4/syncookies.c
> @@ -304,6 +304,59 @@ static int cookie_tcp_reqsk_init(struct sock *sk, struct sk_buff *skb,
> return 0;
> }
>
> +#if IS_ENABLED(CONFIG_BPF)
> +struct request_sock *cookie_bpf_check(struct net *net, struct sock *sk,
> + struct sk_buff *skb)
> +{
> + struct request_sock *req = inet_reqsk(skb->sk);
> + struct inet_request_sock *ireq = inet_rsk(req);
> + struct tcp_request_sock *treq = tcp_rsk(req);
> + struct tcp_options_received tcp_opt;
> + int ret;
> +
> + skb->sk = NULL;
> + skb->destructor = NULL;
> + req->rsk_listener = NULL;
> +
> + memset(&tcp_opt, 0, sizeof(tcp_opt));
> + tcp_parse_options(net, skb, &tcp_opt, 0, NULL);
In patch 2, the bpf prog is passing the tcp_opt to the kfunc. The selftest in
patch 3 is also parsing the tcp-options.
The kernel parses the tcp-option here again to do some checking and req's member
initialization. Can these checking and initialization be done in the
bpf_sk_assign_tcp_reqsk() kfunc instead to avoid the double tcp-option parsing?
> +
> + if (ireq->tstamp_ok ^ tcp_opt.saw_tstamp) {
> + __NET_INC_STATS(net, LINUX_MIB_SYNCOOKIESFAILED);
> + goto reset;
> + }
> +
> + __NET_INC_STATS(net, LINUX_MIB_SYNCOOKIESRECV);
> +
> + if (ireq->tstamp_ok) {
> + if (!READ_ONCE(net->ipv4.sysctl_tcp_timestamps))
> + goto reset;
> +
> + req->ts_recent = tcp_opt.rcv_tsval;
> + treq->ts_off = tcp_opt.rcv_tsecr - tcp_ns_to_ts(false, tcp_clock_ns());
> + }
> +
> + if (ireq->sack_ok && !READ_ONCE(net->ipv4.sysctl_tcp_sack))
> + goto reset;
> +
> + if (ireq->wscale_ok && !READ_ONCE(net->ipv4.sysctl_tcp_window_scaling))
> + goto reset;
> +
> + ret = cookie_tcp_reqsk_init(sk, skb, req);
> + if (ret) {
> + reqsk_free(req);
> + req = NULL;
> + }
> +
> + return req;
> +
> +reset:
> + reqsk_free(req);
> + return ERR_PTR(-EINVAL);
> +}
> +EXPORT_SYMBOL_GPL(cookie_bpf_check);
> +#endif
next prev parent reply other threads:[~2023-12-06 0:19 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-05 1:34 [PATCH v4 bpf-next 0/3] bpf: tcp: Support arbitrary SYN Cookie at TC Kuniyuki Iwashima
2023-12-05 1:34 ` [PATCH v4 bpf-next 1/3] bpf: tcp: Handle BPF SYN Cookie in cookie_v[46]_check() Kuniyuki Iwashima
2023-12-06 0:19 ` Martin KaFai Lau [this message]
2023-12-06 1:29 ` Kuniyuki Iwashima
2023-12-06 3:11 ` Martin KaFai Lau
2023-12-06 5:58 ` Kuniyuki Iwashima
2023-12-05 1:34 ` [PATCH v4 bpf-next 2/3] bpf: tcp: Support arbitrary SYN Cookie Kuniyuki Iwashima
2023-12-06 1:20 ` Martin KaFai Lau
2023-12-06 1:42 ` Kuniyuki Iwashima
2023-12-05 1:34 ` [PATCH v4 bpf-next 3/3] selftest: bpf: Test bpf_sk_assign_tcp_reqsk() Kuniyuki Iwashima
2023-12-05 2:13 ` Alexei Starovoitov
2023-12-05 3:00 ` Kuniyuki Iwashima
2023-12-06 6:39 ` Martin KaFai Lau
2023-12-07 6:56 ` Kuniyuki Iwashima
2023-12-09 1:27 ` Martin KaFai Lau
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