Re: [dpdk-dev] [PATCH v3 1/2] lib/security: add support for get metadata

[Anoob <anoob.joseph@caviumnetworks.com>]

Hi Akhil,

See inline.

Thanks,
Anoob

On 12/04/2017 02:58 PM, Akhil Goyal wrote:
> Hi Anoob,
>
> On 11/24/2017 5:52 PM, Anoob wrote:
>> Hi Akhil, Radu
>>
>> PLease see inline.
>>
>> Thanks,
>>
>> Anoob
>>
>>
>> On 11/24/2017 05:04 PM, Akhil Goyal wrote:
>>> Hi Radu,
>>> On 11/24/2017 4:47 PM, Radu Nicolau wrote:
>>>>
>>>>
>>>> On 11/24/2017 10:55 AM, Akhil Goyal wrote:
>>>>> On 11/24/2017 3:09 PM, Radu Nicolau wrote:
>>>>>> Hi,
>>>>>>
>>>>>> Comment inline
>>>>>>
>>>>>>
>>>>>> On 11/24/2017 8:50 AM, Akhil Goyal wrote:
>>>>>>> Hi Anoob, Radu,
>>>>>>> On 11/23/2017 4:49 PM, Anoob Joseph wrote:
>>>>>>>> In case of inline protocol processed ingress traffic, the 
>>>>>>>> packet may not
>>>>>>>> have enough information to determine the security parameters 
>>>>>>>> with which
>>>>>>>> the packet was processed. In such cases, application could get 
>>>>>>>> metadata
>>>>>>>> from the packet which could be used to identify the security 
>>>>>>>> parameters
>>>>>>>> with which the packet was processed.
>>>>>>>>
>>>>>>>> Signed-off-by: Anoob Joseph <anoob.joseph@caviumnetworks.com>
>>>>>>>> ---
>>>>>>>> v3:
>>>>>>>> * Replaced 64 bit metadata in conf with (void *)userdata
>>>>>>>> * The API(rte_security_get_pkt_metadata) would return void * 
>>>>>>>> instead of
>>>>>>>>    uint64_t
>>>>>>>>
>>>>>>>> v2:
>>>>>>>> * Replaced get_session and get_cookie APIs with 
>>>>>>>> get_pkt_metadata API
>>>>>>>>
>>>>>>>>   lib/librte_security/rte_security.c        | 13 +++++++++++++
>>>>>>>>   lib/librte_security/rte_security.h        | 19 
>>>>>>>> +++++++++++++++++++
>>>>>>>>   lib/librte_security/rte_security_driver.h | 16 ++++++++++++++++
>>>>>>>>   3 files changed, 48 insertions(+)
>>>>>>>>
>>>>>>>> diff --git a/lib/librte_security/rte_security.c 
>>>>>>>> b/lib/librte_security/rte_security.c
>>>>>>>> index 1227fca..a1d78b6 100644
>>>>>>>> --- a/lib/librte_security/rte_security.c
>>>>>>>> +++ b/lib/librte_security/rte_security.c
>>>>>>>> @@ -108,6 +108,19 @@ rte_security_set_pkt_metadata(struct 
>>>>>>>> rte_security_ctx *instance,
>>>>>>>>                              sess, m, params);
>>>>>>>>   }
>>>>>>>>   +void *
>>>>>>>> +rte_security_get_pkt_metadata(struct rte_security_ctx *instance,
>>>>>>>> +                  struct rte_mbuf *pkt)
>>>>>>> Can we rename pkt with m. Just to make it consistent with the 
>>>>>>> set API.
>>>>>>>> +{
>>>>>>>> +    void *md = NULL;
>>>>>>>> +
>>>>>>>> + RTE_FUNC_PTR_OR_ERR_RET(*instance->ops->get_pkt_metadata, NULL);
>>>>>>>> +    if (instance->ops->get_pkt_metadata(instance->device, pkt, 
>>>>>>>> &md))
>>>>>>>> +        return NULL;
>>>>>>>> +
>>>>>>>> +    return md;
>>>>>>>> +}
>>>>>>>
>>>>>>> Pkt metadata should be set by user i.e. the application, and the 
>>>>>>> driver need not be aware of the format and the values of the 
>>>>>>> metadata.
>>>>>>> So setting the metadata in the driver and getting it back from 
>>>>>>> the driver does not look a good idea.
>>>>>>>
>>>>>>> Is it possible, that the application define the metadata on its 
>>>>>>> own and set it in the library itself without the call to the 
>>>>>>> driver ops.
>> My first patch was along those lines. Can you take a look at that and 
>> give your comments?
>>
>> If we add this metadata in rte_security_session, we can achieve the 
>> above behavior without driver maintaining the metadata. But from the 
>> packet, application will have to first get the security session. And 
>> then application can get the metadata by calling "get metadata" with 
>> rte_security_session as the argument. So we will need a "get_session" 
>> API(which reaches the driver) and then do "get_app_metadata".
> In that case also, the application cannot set metadata independently.
> It will rather become more complex.
> It is better that we document this properly in the documentation as 
> discussed in my/Radu's previous mail.
I'll update the documentation with this behavior and will send a new patch.
>>>>>> I'm not sure I understand here; even in our case (ixgbe) the 
>>>>>> driver sets the metadata and it is aware of the format - that is 
>>>>>> the whole idea. This is why we added the set_metadata API, to 
>>>>>> allow the driver to inject extra information into the mbuf, 
>>>>>> information that is driver specific and derived from the security 
>>>>>> session, so it makes sense to also have a symmetric get_metadata.
>>>>>> Private data is the one that follows those rules, i.e. 
>>>>>> application specific and driver transparent.
>>>>>
>>>>> As per my understanding of the user metadata, it should be in 
>>>>> control of the application, and the application shall know the 
>>>>> format of that. Setting in driver will disallow this.
>>>>> Please let me know if my understanding is incorrect.
>> Your understanding is correct. That' the requirement.
>>>>>
>>>>> If at all, some information is needed to be set on the basis of 
>>>>> driver, then application can get that information from the driver 
>>>>> and then set it in the packet metadata in its own way/format.
>>>>
>>>> The rte_security_set_pkt_metadata() doc defines the metadata as 
>>>> "device-specific defined metadata" and also takes a device specific 
>>>> params pointer, so the symmetric function is to be expected to work 
>>>> in the same way, i.e. return device specific metadata associated 
>>>> with the security session and instance and mbuf. How is this 
>>>> metadata stored is not specified in the security API, so the PMD 
>>>> implementation have the flexibility.
>> The requirement in this case isn't exactly parallel to 
>> "set_pkt_metadata". May be we can drop making it symmetric?
>>>>
>>>
>>> Yes it was defined that way and I did not noticed this one at the 
>>> time of it's implementation.
>>> Here, my point is that the application may be using mbuf udata for 
>>> it's own functionality, it should not be modified in the driver.
>>>
>>> However, if we need to do this, then we may need to clarify in the 
>>> documentation that for security, udata shall be set with the 
>>> rte_security_set_pkt_metadata() and not otherwise.
>>>
>>> -Akhil
>>
>>
>