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

[Andrii Tseglytskyi <andrii.tseglytskyi@xxxxxxxxxxxxxxx>]

Hi Julien,

On Fri, Jul 4, 2014 at 5:35 PM, Julien Grall <julien.grall@xxxxxxxxxx> 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.

Right. Do you think that some kind of security checks needed here?


>
> Regards,
>
> --
> Julien Grall



-- 

Andrii Tseglytskyi | Embedded Dev
GlobalLogic
www.globallogic.com

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