Re: [PATCH v6 3/6] crypto: AF_ALG -- add asymmetric cipher interface

Mat Martineau
2016-06-09T18:27:18Z

On Thu, 9 Jun 2016, Stephan Mueller wrote:

> Am Donnerstag, 9. Juni 2016, 11:18:04 schrieb Mat Martineau:
>
> Hi Mat,
>
>>> Or is your concern that the user space interface restricts things too much
>>> and thus prevents a valid use case?
>>
>> The latter - my primary concern is the constraint this places on userspace
>> by forcing larger buffer sizes than might be necessary for the operation.
>> struct akcipher_request has separate members for src_len and dst_len, and
>> dst_len is documented as needing "to be at least as big as the expected
>> result depending on the operation". Not the maximum result, the expected
>> result. It's also documented that the cipher will generate an error if
>> dst_len is insufficient and update the value with the required size.
>>
>> I'm updating some userspace TLS code that worked with an earlier, unmerged
>> patch set for AF_ALG akcipher (from last year). The read calls with
>> shorter buffers were the main porting problem.
>
> I see -- are you proposing to drop that check entirely?

Yes.

Best regards,

--
Mat Martineau
Intel OTC