Re: Bug report connect to VM with Vagrant

From: Bagas Sanjaya
Date: Thu Nov 30 2023 - 09:10:57 EST


On Thu, Nov 30, 2023 at 01:55:06PM +0000, Shachar Kagan wrote:
> Hi Eric,
>
> I have an issue that bisection pointed at this patch:
> commit 0a8de364ff7a14558e9676f424283148110384d6
> tcp: no longer abort SYN_SENT when receiving some ICMP
>
> 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 ‘Vagrant up’ fails when the VM is in halt 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 ‘Guest communication could not be established! This is usually because SSH is not running, the authentication information was 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@xxxxxxxxxx>
> 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 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@xxxxxxxxxx>
> Cc: David Morley <morleyd@xxxxxxxxxx>
> Cc: Neal Cardwell <ncardwell@xxxxxxxxxx>
> Cc: Yuchung Cheng <ycheng@xxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
>
> [2]
> Vagrant up stdout:
> Bringing machine 'player1' up with 'libvirt' provider...
> ==> player1: Creating shared folders metadata...
> ==> player1: Starting domain.
> ==> player1: Domain launching with graphics connection settings...
> ==> player1: -- Graphics Port: 5900
> ==> player1: -- Graphics IP: 127.0.0.1
> ==> player1: -- Graphics Password: Not defined
> ==> player1: -- Graphics Websocket: 5700
> ==> player1: Waiting for domain to get an IP address...
> ==> 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
> ==> player1: Attempting graceful shutdown of VM...
> ==> player1: Attempting graceful shutdown of VM...
> ==> player1: Attempting graceful shutdown of VM...
> player1: Guest communication could not be established! This is usually because
> player1: SSH is not running, the authentication information was changed,
> player1: or some other networking issue. Vagrant will force halt, if
> player1: capable.
> ==> player1: Attempting direct shutdown of domain...
>
>

Thanks for the regression report. I'm adding it to regzbot:

#regzbot ^introduced: 0a8de364ff7a14
#regzbot title: starting Vagrant VM fails due to not aborting SYN_SENT

--
An old man doll... just what I always wanted! - Clara

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