Re: [PATCH for-next v2 2/2] RDMA/erdma: Support non-4K page size in doorbell allocation

[Cheng Xu <chengyou@linux.alibaba.com>]

On 3/23/23 7:53 PM, Jason Gunthorpe wrote:
> On Thu, Mar 23, 2023 at 02:57:49PM +0800, Cheng Xu wrote:
>>
>>
>> On 3/22/23 10:01 PM, Jason Gunthorpe wrote:
>>> On Wed, Mar 22, 2023 at 09:30:41PM +0800, Cheng Xu wrote:
>>>>
>>>>
>>>> On 3/22/23 7:54 PM, Jason Gunthorpe wrote:
<...>
>>
>> It's much clear, thanks for your explanation and patience.
>>
>> Back to erdma context, we have rethought our implementation. For QPs,
>> we have a field *wqe_index* in SQE/RQE, which indicates the validity
>> of the current WQE. Incorrect doorbell value from other processes can
>> not corrupt the QPC in hardware due to PI range and WQE content
>> validation in HW.
> 
> No, validating the DB content is not acceptable security. The attacker
> process can always generate valid content if it tries hard enough.
>

Oh, you may misunderstand what I said, our HW validates the *WQE* content,
not *DB* content. The attacker can not generate the WQE of other QPs. This
protection and correction is already implemented in our HW.

> The only acceptable answer is to do like every other NIC did and link
> the DB register to the HW object it is allowed to affect.
> 

Emm, still not acceptable with WQE content validation? If it's acceptable,
will reduce some works.

Thanks,
Cheng Xu