Re: [Xen-devel] [PATCH v02 6/7] arm: introduce do_translate_pagetable hypercall

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Fri, 2014-07-04 at 15:35 +0100, Julien Grall wrote:
> Hi Andrii,
> 
> On 26/06/14 12:07, Andrii Tseglytskyi wrote:
> > +long do_translate_pagetable(int cmd, 
> > XEN_GUEST_HANDLE_PARAM(xen_pagetable_addr_t) pgt_addr)
> > +{
> > +    struct xen_pagetable_addr pgt;
> > +    struct mmu_info *mmu = NULL;
> > +
> > +    if ( copy_from_guest(&pgt, pgt_addr, 1) )
> > +        return -EFAULT;
> > +
> > +    mmu = mmu_lookup(pgt.reg);
> > +    if ( !mmu )
> > +    {
> > +        pr_mmu("can't get mmu for addr 0x%08x", pgt.reg);
> > +        return -EINVAL;
> > +    }
> > +
> > +    pgt.maddr = mmu_translate_pagetable(mmu, pgt.paddr);
> > +
> > +    return copy_to_guest(pgt_addr, &pgt, 1);
> > +}
> > +
> 
> AFAIU, nothing prevents a malicious guest to call this hypercall and 
> screw the pagetable of the MMU.

It's R/O, isn't it?

(I sure hope so!)

Ian.



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