Re: [PATCH net-next 2/2] tcp: no longer abort SYN_SENT when receiving some ICMP (II)

[Jason Xing <kerneljasonxing@gmail.com>]

On Thu, Apr 18, 2024 at 12:59 AM Eric Dumazet <edumazet@google.com> wrote:
>
> Notes:
>
>  - A prior version of this patch in commit
>    0a8de364ff7a ("tcp: no longer abort SYN_SENT when
>    receiving some ICMP") had to be reverted.
>
>  - We found the root cause, and fixed it in prior patch
>    in the series.
>
>  - Many thanks to Dragos Tatulea !
>
> Currently, non fatal ICMP messages received on behalf
> of SYN_SENT sockets do call tcp_ld_RTO_revert()
> to implement RFC 6069, but immediately call tcp_done(),
> thus aborting the connect() attempt.
>
> This violates RFC 1122 following requirement:
>
> 4.2.3.9  ICMP Messages
> ...
>           o    Destination Unreachable -- codes 0, 1, 5
>
>                  Since these Unreachable messages indicate soft error
>                  conditions, TCP MUST NOT abort the connection, and it
>                  SHOULD make the information available to the
>                  application.
>
> This patch makes sure non 'fatal' ICMP[v6] messages do not
> abort the connection attempt.
>
> It enables RFC 6069 for SYN_SENT sockets as a result.
>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Neal Cardwell <ncardwell@google.com>
> Tested-by: Dragos Tatulea <dtatulea@nvidia.com>

Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>

Finally!!