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    SubjectRe: [PATCH 26/26] x86, pkeys: Documentation

    * Dave Hansen <dave@sr71.net> wrote:

    > > I.e. AFAICS pkeys could be used to create true '--x' permissions for executable
    > > (user-space) pages.
    >
    > Just remember that all of the protections are dependent on the contents of PKRU.
    > If an attacker controls the Access-Disable bit in PKRU for the executable-only
    > region, you're sunk.

    The same is true if the attacker can execute mprotect() calls.

    > But, that either requires being able to construct and execute arbitrary code
    > *or* call existing code that sets PKRU to the desired values. Which, I guess,
    > gets harder to do if all of the the wrpkru's are *in* the execute-only area.

    Exactly. True --x executable regions makes it harder to 'upgrade' limited attacks.

    Thanks,

    Ingo


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