On Wed, May 13, 2020 at 3:36 PM Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
>
> It's used for both.
Daniel, BPF real;ly needs to make up its mind about that.
You *cannot* use ti for both.
Yes, it happens to work on x86 and some other architectures.
But on other architectures, the exact same pointer value can be a
kernel pointer or a user pointer.
> Given this is enabled on pretty much all program types, my
> assumption would be that usage is still more often on kernel memory than user one.
You need to pick one.
If you know it is a user pointer, use strncpy_from_user() (possibly
with disable_pagefault() aka strncpy_from_user_nofault()).
And if you know it is a kernel pointer, use strncpy_from_unsafe() (aka
strncpy_from_kernel_nofault()).
You really can't pick the "randomly one or the other guess what I mean " option.
Linus
