[lkml]   [1998]   [Aug]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: kill -9 <pid of X>
> Remember, we're talking about defending against signals from a hostile
> root who wants to crash the video card. In this scenario, not even the
> kernel can do it -- root can install a kernel module which overwrites

Signals are the uninteresting end of the problem, being root is uninteresting.
The bigger problems are that X11 is subject to being killed with sig 9
(which with a horrible kernel hack can be blocked for iopl3 processes)

Now you need the signal 9 blocking hack because any parent process that
sits around to catch X failures does _not_ know the exact state of the
video card.

The related problems are SAK - which is defined to kill all processes on that
VT and out of resource kills from the kernel (oom()). SAK is not that big
a deal - a setuid "sak signal" ioctl akin to the way you take over console
switching covers it. Oom is trickier.

> Boy, it's no wonder Linus is grumpy these days.

Being grumpy and being right are different things.

I'd agree however - you don't need to put all mode switching code in
kernel if you allow iopl3 proceses to lock out sig 9 and you provide
a sak hook. Oom should be solvable its just harder


To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:44    [W:0.418 / U:7.972 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site