Re: [PATCH v6 00/25] Enable CET Virtualization

[Yang, Weijiang]

Kindly ping maintainers for KVM part review, thanks!

On 9/14/2023 2:33 PM, Yang Weijiang wrote:
> Control-flow Enforcement Technology (CET) is a kind of CPU feature used
> to prevent Return/CALL/Jump-Oriented Programming (ROP/COP/JOP) attacks.
> It provides two sub-features(SHSTK,IBT) to defend against ROP/COP/JOP
> style control-flow subversion attacks.
>
> Shadow Stack (SHSTK):
>    A shadow stack is a second stack used exclusively for control transfer
>    operations. The shadow stack is separate from the data/normal stack and
>    can be enabled individually in user and kernel mode. When shadow stack
>    is enabled, CALL pushes the return address on both the data and shadow
>    stack. RET pops the return address from both stacks and compares them.
>    If the return addresses from the two stacks do not match, the processor
>    generates a #CP.
>
> Indirect Branch Tracking (IBT):
>    IBT introduces new instruction(ENDBRANCH)to mark valid target addresses of
>    indirect branches (CALL, JMP etc...). If an indirect branch is executed
>    and the next instruction is _not_ an ENDBRANCH, the processor generates a
>    #CP. These instruction behaves as a NOP on platforms that doesn't support
>    CET.
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