Date: Tue, 3 Dec 2019 12:34:14 +0000 From: Simon McVittie <smcv@...ian.org> To: oss-security@...ts.openwall.com Subject: Re: virtual consoles On Mon, 02 Dec 2019 at 08:56:38 -0800, Tavis Ormandy wrote: > unprivileged users can start a new X server and switch virtual > console, even over ssh. > > e.g. > > $ dbus-send --system --print-reply --dest=org.freedesktop.login1 /org/freedesktop/login1/seat/seat0 org.freedesktop.login1.Seat.SwitchTo uint32:2 If a uid who is not already the owner of the current VT on the seat can do this, then that's probably a bug? If you think so, please report it to the maintainers of logind (which is the component that would have to change to address this). I would have expected this to be gated by a check that the uid of the caller (the D-Bus client, in this case the dbus-send process) matches the uid of the current VT on that seat (so you can voluntarily switch away from your own session, but other users can't force you to), or a polkit check that the caller is root-equivalent, or some combination of those. In particular, checking that the uid matches the VT's owner's uid would be enough to let unprivileged X and Wayland servers implement the expected "switch to other VT" handling for Ctrl+Alt+F1..Ctrl+Alt+F12. smcv
Powered by blists - more mailing lists
Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.