Re: [PATCH v6 00/41] Shadow stacks for userspace

[Kees Cook]

On Sat, Feb 18, 2023 at 01:13:52PM -0800, Rick Edgecombe wrote:
> This series implements Shadow Stacks for userspace using x86's Control-flow 
> Enforcement Technology (CET). CET consists of two related security features: 
> shadow stacks and indirect branch tracking. This series implements just the 
> shadow stack part of this feature, and just for userspace.

Okay, I've done some bare metal testing, and it all looks happy. The
selftest passes, and I can can see the stack address mismatch get
detected if I explicitly rewrite the saved function pointer on the stack:

[INFO] Want normal flow
[INFO] Found 0x401890 @ 0x7fff47cf2ef8
[INFO] Normal execution flow
[INFO] Want to redirect
[INFO] Found 0x401890 @ 0x7fff47cf2ef8
[INFO] Hijacked execution flow
[INFO] Enabling shadow stack
[INFO] Want to redirect
[INFO] Found 0x401890 @ 0x7fff47cf2ef8
Segmentation fault (core dumped)

Tested-by: Kees Cook <keescook@xxxxxxxxxxxx>

-- 
Kees Cook