Messages in this thread | | | Date | Wed, 17 Nov 2010 17:27:34 -0800 | From | Greg KH <> | Subject | Re: tty: add 'active' sysfs attribute to tty0 and console device |
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On Wed, Nov 17, 2010 at 11:56:47PM +0000, Alan Cox wrote: > > Brilliant conclusion. If you have mounted it, you own it. But you can > > not make your inactive session mount another new one. It's like this > > since ages. Hint: try stuff before hitting reply too fast. :) > > Except during the window when screen switching, or of course you could > just ssh in remotely and gdb or similar a process with it as controlling > tty running on your console and issue a vt switch back, then mount it. > Ironically the move from a root owned X server has made that much simpler > to automate, although it was always possible. > > Given you can often guess from the idle data if the victim has gone away > from the box it's not ideal. Even better any mess will appear on my > display and get hidden when I flip it back. > > The only way to stop that is to make use of the display locking facility > which takes us back where we began in saying that a usable interface is > going to need to lock the display. > > At that point the current console owner has to choose to allow the > console to be switched which can be limited effectively to physical > console access and done synchronously. In turn that means to abuse it I > already have physical access to the other users key so could just as > easily steal it and the software security is therefore sufficient.
Ok, we are way-off-topic here from the original points.
Which are: - the existing ioctl is broken and no userspace program can use it properly, so it might as well be removed. - Kay's patch is one proposed solution for what userspace is wanting to learn about ttys. Werner's is another one.
So, what to do?
I can do any one, or multiple things from the following options:
- disable the existing ioctl to return an error so that no new userspace program starts to use it thinking it is valid - accept Werner's patch for those who like proc files - accept Kay's patch
Any suggestions?
thanks,
greg k-h
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