Re: [PATCH v18 02/25] x86/cet/shstk: Add Kconfig option for user-mode control-flow protection

Dave Hansen
2021-01-29T19:43:30Z

On 1/27/21 1:25 PM, Yu-cheng Yu wrote:
> + help
> + Control-flow protection is a hardware security hardening feature
> + that detects function-return address or jump target changes by
> + malicious code.

It's not really one feature. I also think it's not worth talking about
shadow stacks or indirect branch tracking in *here*. Leave that for
Documentation/.

Just say:

Control-flow protection is a set of hardware features which
place additional restrictions on indirect branches. These help
mitigate ROP attacks.

... and add more in the IBT patches.

> Applications must be enabled to use it, and old
> + userspace does not get protection "for free".
> + Support for this feature is present on processors released in
> + 2020 or later. Enabling this feature increases kernel text size
> + by 3.7 KB.

Did any CPUs ever get released that have this? If so, name them. If
not, time to change this to 2021, I think.