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From:   Eric Dumazet <edumazet@google.com>
Date:   Thu, 30 Nov 2023 15:01:56 +0100
Message-ID: <CANn89iKvG5cTNROyBF32958BzATfXysh4zLk5nRR6fgi08vumA@mail.gmail.com>
Subject: Re: Bug report connect to VM with Vagrant
To:     Shachar Kagan <skagan@nvidia.com>
Cc:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "kuba@kernel.org" <kuba@kernel.org>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Yishai Hadas <yishaih@nvidia.com>, Ido Kalir <idok@nvidia.com>,
        Topaz Uliel <topazu@nvidia.com>,
        Shirly Ohnona <shirlyo@nvidia.com>,
        Ziyad Atiyyeh <ziyadat@nvidia.com>
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On Thu, Nov 30, 2023 at 2:55=E2=80=AFPM Shachar Kagan <skagan@nvidia.com> w=
rote:
>
> Hi Eric,
>
> I have an issue that bisection pointed at this patch:
> commit 0a8de364ff7a14558e9676f424283148110384d6
> tcp: no longer abort SYN_SENT when receiving some ICMP
>

Please provide tcpdump/pcap captures.

 It is hard to say what is going on just by looking at some application log=
s.


> Full commit message at [1].
>
> The issue appears while using Vagrant to manage nested VMs.
> The steps are:
> * create vagrant file
> * vagrant up
> * vagrant halt (VM is created but shut down)
> * vagrant up - fail
>
> Turn on a VM with =E2=80=98Vagrant up=E2=80=99 fails when the VM is in ha=
lt state. When the VM hasn't been created yet, 'Vagrant up' passes.
> The failure occurs in the Net-SSH connection to the VM step.
> Vagrant error is =E2=80=98Guest communication could not be established! T=
his is usually because SSH is not running, the authentication information w=
as changed, or some other networking issue.'
> We use a new version of vagrant-libvirt.
> Turn on the VM with virsh instead of vagrant works.
>
> Stdout[2] bellow.
>
> Any idea what may cause the error with your patch?
>
> Thanks,
> Shachar Kagan
>
> [1]
> commit 0a8de364ff7a14558e9676f424283148110384d6
> Author: Eric Dumazet <edumazet@google.com>
> Date:   Tue Nov 14 17:23:41 2023 +0000
>
>     tcp: no longer abort SYN_SENT when receiving some ICMP
>
>     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 i=
t
>                      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: David Morley <morleyd@google.com>
>     Cc: Neal Cardwell <ncardwell@google.com>
>     Cc: Yuchung Cheng <ycheng@google.com>
>     Signed-off-by: David S. Miller <davem@davemloft.net>
>
> [2]
> Vagrant up stdout:
> Bringing machine 'player1' up with 'libvirt' provider...
> =3D=3D> player1: Creating shared folders metadata...
> =3D=3D> player1: Starting domain.
> =3D=3D> player1: Domain launching with graphics connection settings...
> =3D=3D> player1:  -- Graphics Port:      5900
> =3D=3D> player1:  -- Graphics IP:        127.0.0.1
> =3D=3D> player1:  -- Graphics Password:  Not defined
> =3D=3D> player1:  -- Graphics Websocket: 5700
> =3D=3D> player1: Waiting for domain to get an IP address...
> =3D=3D> player1: Waiting for machine to boot. This may take a few minutes=
...
>     player1: SSH address: 192.168.123.61:22
>     player1: SSH username: vagrant
>     player1: SSH auth method: private key
> =3D=3D> player1: Attempting graceful shutdown of VM...
> =3D=3D> player1: Attempting graceful shutdown of VM...
> =3D=3D> player1: Attempting graceful shutdown of VM...
>     player1: Guest communication could not be established! This is usuall=
y because
>     player1: SSH is not running, the authentication information was chang=
ed,
>     player1: or some other networking issue. Vagrant will force halt, if
>     player1: capable.
> =3D=3D> player1: Attempting direct shutdown of domain...
>
>