On Fri, Jun 14, 2019 at 7:04 AM maowenan <maowe...@huawei.com> wrote:
> I agree that this is a special case.
> I propose one point about the sequence of synack, if two synack with two
> different
> sequence since the time elapse 64ns, this issue disappear.
>
> tcp_conn_request->tcp_v4_init_seq->secure_tcp_seq->seq_scale
> static u32 seq_scale(u32 seq)
> {
> /*
> * As close as possible to RFC 793, which
> * suggests using a 250 kHz clock.
> * Further reading shows this assumes 2 Mb/s networks.
> * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
> * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
> * we also need to limit the resolution so that the u32 seq
> * overlaps less than one time per MSL (2 minutes).
> * Choosing a clock of 64 ns period is OK. (period of 274 s)
> */
> return seq + (ktime_get_real_ns() >> 6);
> }
>
> So if the long delay larger than 64ns, the seq is difference.
The core issue has nothing to do with syncookies.
Are you sure you really understand this stack ?
