xterm started on the remote server (via winswitch) runs with umask 0000. This has security impact as files/directories created by users are then world-writable. Expected: some sensible default like 002 or 022.
Version: winswitch 0.12.23-1, xpra 2.1.1-r16658-1 Possible cause: winswitch server assumes umask will be set in /etc/bashrc. That is true on Red Hat derived systems. But it is not true on Ubuntu (tested 16.04 LTS) where I think umask is expected to be set by PAM session (pam_umask.so).
Perhaps related, the PAM file provided by /etc/pam.d/xpra seems to assume a Red Hat style system and most of the PAM modules referenced there do not exist on a Ubuntu system.
The pam file is only used when we start sessions via the system wide proxy.
I assume that the umask is correctly set if we start sessions with
Best way to fix this is to figure out the correct contents for
/etc/pam.d/xpra for all Debian / Ubuntu distributions. Oh, that's going to be fun seeing the complete lack of any clear documentation on the subject.
Just tested on a bunch of Debian distros:
So, although the umask is different, it isn't set to 0000 and is in fact more strict.
pam_umask module is yet another Ubuntu-only thing.
I've tried removing system-auth from the
/etc/pam.d/xpra file and adding:
@include common-account @include common-session @include common-password
The pam open code succeeds but the umask is unchanged after the call. (common session includes:
session optional pam_umask.so)
And... that's all I've got time for. It doesn't look like a big problem anyway since the umask is stricter. Hopefully someone who understands what Ubuntu is doing in this area can fix this.
Not heard back, closing.
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/1635