Re: [PATCH RFC RFT 2/5] fork: Add shadow stack support to clone3()

[Edgecombe, Rick P]

On Thu, 2023-10-26 at 13:40 -0700, Deepak Gupta wrote:
> 
> FWIW, from arch specific perspective, RISC-V shadow stack extension
> has
> `ssamoswap` to perform this token exchange. But I understand x86 has
> this
> limitation (not sure about arm GCS).
> 
>  From security perspective:--
> Someone having ability to execute clone3 with control on input,
> probably
> already achieved some level of control flow bending because they need
> to
> corrupt memory and then carefully control registers input to clone3.
> Although if it is purely a data oriented gadget, I think it is
> possible.

struct clone_args should be data somewhere, at least temporarily.

> 
> Since this RFC is mostly concerned about `size` of shadow stack. I
> think
> we should limit it to size only.

Seems reasonable to me. It still leaves open the option of adding an
shadow stack address field later AFAICT.