Re: [PATCH 1/2 v2] kprobe: Do not use uaccess functions to access kernel memory that can fault

From: Steven Rostedt
Date: Tue Feb 19 2019 - 11:18:07 EST

[ Added Masami too. Start of thread is here: ]

On Mon, 18 Feb 2019 10:23:44 -0800
Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

> So it would be good to not just say "user or kernel", but actually say
> what *kind* of kernel access it expects.

Note, kprobes are a different kind of beast. I've used kprobes to probe
userspace information as well as kernel. Heck, I could see someone
even using kprobes to probe IO memory to check if a device is doing
what they expect it's doing.

Basically, a kprobe is mostly used for debugging what's happening in a
live kernel, to read any address. But for those that are more security
minded, perhaps we could add "layers" via CONFIG or /sys files that
prevent kprobes from doing certain kinds of probes?

-- Steve