Hi! > > root isn't really a problem from a security PoV (well, maybe it is if the > > operation isn't constrained by capabilities). SAK can't protect you from > > root. > > > > _Normal_ userspace behaviour running a root process is a problem if it > > blocks these handles, though, both for SAK and regular SysRQ. I have lost > > count of how many times SysRQ+SUB delivered me from filesystem corruption > > and very annoying problems, both at home and at work. > > > > We are sort of trusting userspace to not break the one way out from severly > > hung systems while doing its normal day-to-day operations (as opposed to > > deliberately disabling SysRQ or remapping SAK, etc). If userspace disables sysrq during normal operation, that makes it useless. If normal user could do that, that's a security problem. > > > That would require moving "these things", including their state > > > machines, into input core otherwise it would not know what events can be > > > trappable and which should be passed through. Or we should get rid of > > > EVIOCGRAB. > > > > Maybe we can add a flags field to input devices and input handlers, to be > > able to have the core behave differently when needed, without moving > > everything into the input core? Would that work, or would it need too much > > churn in the core? > > The problem is that device does not know what SysRq and especially SAK are. > User can reassign key codes and key symbols easily. That was not case in original implementation; it had hardcoded keymap. > I don't think we had any issues like this since 2.5 so I would not worry > about userspace too much. If anything we just need to review what stuff > we run as root (we do that anyway, right?). Hehe. If X can break sysrq, that's both X and sysrq problem. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
