Re: [PATCH 3/3] crypto: qce: ice: Add support for Inline Crypto Engine

[AnilKumar Chimata <anilc@codeaurora.org>]

Hi Theodore,

Thanks for the comments,

On 2018-10-17 22:34, Theodore Y. Ts'o wrote:
> First, thanks for the effort for working on getting the core ICE
> driver support into upstreamable patches.
> 
> On Wed, Oct 17, 2018 at 08:47:56PM +0530, AnilKumar Chimata wrote:
>> +2) Per File Encryption (PFE)
>> +Per File Manager(PFM) calls QSEECom api to create the key. PFM has a 
>> peer comp-
>> +onent(PFT) at kernel layer which gets the corresponding key index 
>> from PFM.
>> ...
>> +Further Improvements
>> +====================
>> +Currently, Due to PFE use case, ICE driver is dependent upon 
>> dm-req-crypt to
>> +provide the keys as part of request structure. This couples ICE 
>> driver with
>> +dm-req-crypt based solution. It is under discussion to expose an 
>> IOCTL based
>> +and registration based interface APIs from ICE driver. ICE driver 
>> would use
>> +these two interfaces to find out if any key exists for current 
>> request. If
>> +yes, choose the right key index received from IOCTL or registration 
>> based
>> +APIs. If not, dont set any crypto parameter in the request.
> 
> However, this documentation is referencing components which are not in
> the mainline kernel.

Sure, will clean the documentation and try to minimize the unknown 
components. Provided these details for better understanding of the flow.

> 
> In the long term, what I'd like to see for per-file key support is a
> clean solution which interfaces with the in-kernel fscrypt-enabled
> file systems (e.g., f2fs and ext4).  What I think we need to do is to

Agree, we are working on making per-file key (PFK) driver generic to 
support any file system.

> add a field in the bio structure which references a key id, and then
> define a bdi-specific interface which allows the file system to
> register a struct key and get a key id.  Use of the key id will be
> refcounted, so the device driver knows how many I/O operations are in
> flight using a particular key --- since each ICE hardware will have a
> different number of active keys that it can support.

Understand the point here, we will consider this refcount while working 
on upstreamable PFK driver.

> 
> Until that's there, at least for the upstream documentation, I think
> it would be better to drop mention of code that is not yet upstream
> --- and which may have problems ever going upstream in their current
> form.

Will clean the documentation.

> 
> (I haven't checked in a while, but last time I looked the code in
> question blindly dereferenced private pointers assuming that the only
> two file systems that could ever use ICE were ext4 and f2fs....  not
> that the code used by Google handsets were _that_ much cleaner, but
> at least we dropped in a crypto key into the struct bio, instead of
> playing unnatural games with private pointers from the wrong
> abstraction layer.  :-)

before upstreaming the PFK drivers, we will try to avoid private pointer 
dereferences to achieve better abstraction to file system.

> 
> 						- Ted