Re: Behavior of /dev/pts in a jail?

Quoting Michael Gmelin <grembo@freebsd.org> (from Wed, 9 Feb 2022  
12:56:49 +0100):

> I was able to reproduce the issue locally.
>
> The problem is caused by jexec inheriting the pty from the jail host.
>
> If you use a pty that was created inside of the jail,  
> gpg-agent/pinentry works as expected.
>
> This can be accomplished, e.g., by running tmux inside of the jail:
>
>     jexec gpgtest
>     pkg install tmux
>     tmux
>     gpg --gen-key
>
> Running sshd inside of the jail and connecting to it using ssh has  
> the same effect.

I confirm (with ssh instead of jexec) the behavior.

What I don't understand is how this works. ls is not build-in to the  
shell. So how can it be that the jexec-ed shell can fork ls and it  
sees the content of /dev/pts/, and the ls forked from  
gpg->gpg-agent->pinentry-wrapper can't? And how could we fix this (or  
why wouldn't we want to fix it)?

Bye,
Alexander.

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