Re: [dpdk-dev] [RFC] ethdev: allow multiple security sessions to use one rte flow

[Anoob Joseph <anoobj@marvell.com>]

Hi Akhil,

Please see inline.

Thanks,
Anoob

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Akhil Goyal
> Sent: Friday, August 16, 2019 2:02 PM
> To: Anoob Joseph <anoobj@marvell.com>; Adrien Mazarguil
> <adrien.mazarguil@6wind.com>; Declan Doherty
> <declan.doherty@intel.com>; Pablo de Lara
> <pablo.de.lara.guarch@intel.com>; Thomas Monjalon
> <thomas@monjalon.net>
> Cc: Jerin Jacob Kollanukkaran <jerinj@marvell.com>; Narayana Prasad Raju
> Athreya <pathreya@marvell.com>; Ankur Dwivedi
> <adwivedi@marvell.com>; Shahaf Shuler <shahafs@mellanox.com>;
> Hemant Agrawal <hemant.agrawal@nxp.com>; Matan Azrad
> <matan@mellanox.com>; Yongseok Koh <yskoh@mellanox.com>; Wenzhuo
> Lu <wenzhuo.lu@intel.com>; Konstantin Ananyev
> <konstantin.ananyev@intel.com>; Radu Nicolau <radu.nicolau@intel.com>;
> dev@dpdk.org
> Subject: Re: [dpdk-dev] [RFC] ethdev: allow multiple security sessions to use
> one rte flow
> 
> Hi Anoob,
> >
> > Hi Akhil,
> >
> > > > > >
> > > > > > The rte_security API which enables inline protocol/crypto
> > > > > > feature mandates that for every security session an rte_flow is
> created.
> > > > > > This would internally translate to a rule in the hardware
> > > > > > which would do packet
> > > > > classification.
> > > > > >
> > > > > > In rte_securty, one SA would be one security session. And if
> > > > > > an rte_flow need to be created for every session, the number
> > > > > > of SAs supported by an inline implementation would be limited
> > > > > > by the number of rte_flows the PMD would be able to support.
> > > > > >
> > > > > > If the fields SPI & IP addresses are allowed to be a range,
> > > > > > then this limitation can be overcome. Multiple flows will be
> > > > > > able to use one rule for SECURITY processing. In this case,
> > > > > > the security session provided as
> > > > > conf would be NULL.
> > >
> > > SPI values are normally used to uniquely identify the SA that need
> > > to be applied on a particular flow.
> > > I believe SPI value should not be a range for applying a particular
> > > SA or session.
> > >
> > > Plain packet IP addresses can be a range. That is not an issue.
> > > Multiple plain packet flows can use the same session/SA.
> > >
> > > Why do you feel that security session provided should be NULL to
> > > support multiple flows.
> > > How will the keys and other SA related info will be passed to the
> driver/HW.
> >
> > [Anoob] The SA configuration would be done via rte_security session.
> > The proposal here only changes the 1:1 dependency of rte_flow and
> > rte_security session.
> 
> I don't see this dependency for rte_flow and security session.
> Multiple flows can be configured to use the same security session.
> 
> >
> > The h/w could use SPI field in the received packet to identify SA(ie,
> > rte_security session). If the h/w allows to index into a table which
> > holds SA information, then per SPI rte_flow is not required. This is
> > in fact our case. And for PMDs which doesn't do it this way,
> > rte_flow_validate() would fail and then per SPI rte_flow would require to
> be created.
> 
> I am not able to understand the issue here. Flow are validated based on
> some pattern, You can identify the flow based on some parameter(currently
> it is spi in case of inline crypto and also your case).
> You can perform some action based on the security session that you have
> created before validating the flow And that session creation is nowhere
> linked to the type of flow. You can use the same session for as many flows
> you want.
> 
> >
> > In the present model, a security session is created, and then rte_flow
> > will connect ESP packets with one SPI to one security session.
> > Instead, when we create the security session, h/w can populate entries
> > in a DB that would be accessed during data path handling. And the
> > rte_flow could say, all SPI in some range gets inline processed with the
> security session identified with its SPI.
> >
> > Our PMD supports limited number of flow entries but our h/w can do SA
> > lookup without flow entries(using SPI instead). So the current
> > approach of one flow per session is creating an artificial limit to the number
> of SAs that can be supported.
> 
> Ok now I got it. You want to configure a single flow with multiple sessions in
> it.
> But defining a range in SPI and tunnel IP addresses does not make sense. In
> real world applications, Sessions can be created and destroyed at any time
> with varied values of SPI and tunnel IPs. How can One put a range to that.
> 
> I would rather say, you actually do not need the rte_flows to be configured
> for Inline protocol processing. You have configured all the session info in the
> hw while Creating the session and your H/W will be able to identify on the
> basis of SPI value which It has stored in the DB and do all the processing.

[Anoob] Yes. That is the model being followed right now. Concern is, whether this would be deviating from the spec. In other words, we could have devices which would need rte_flow for every rte_security session (ixgbe needs for inline crypto), and then we could have devices which doesn't need per session rte_flow (which is our case). What do you think is the right approach for supporting both kinds of devices?

>  
> What are the changes that you need in the ipsec-secgw for inline proto to
> work, there is No flow processing currently in the inline proto case. Will it not
> work as is for you?

[Anoob] In ipsec-secgw, a default flow would be created per security enabled port with 'conf=NULL' & SPI = 'ANY'. Flow validate would be done to make sure the underlying PMD supports it. For PMDs which doesn't support this model, per SA flow would be created.
 
> Atleast for NXP devices we are able to work as is without any issue.

[Anoob] Just curious, would having such a dependency on rte_flow be an issue for NXP devices?
 
> 
> >
> > >
> > > > > >
> > > > > > Application should do an rte_flow_validate() to make sure the
> > > > > > flow is supported on the PMD.
> > > > > >
> > > > > > Signed-off-by: Anoob Joseph <anoobj@marvell.com>
> > > > > > ---
> > > > > >  lib/librte_ethdev/rte_flow.h | 6 ++++++
> > > > > >  1 file changed, 6 insertions(+)
> > > > > >
> > > > > > diff --git a/lib/librte_ethdev/rte_flow.h
> > > > > > b/lib/librte_ethdev/rte_flow.h index f3a8fb1..4977d3c 100644
> > > > > > --- a/lib/librte_ethdev/rte_flow.h
> > > > > > +++ b/lib/librte_ethdev/rte_flow.h
> > > > > > @@ -1879,6 +1879,12 @@ struct rte_flow_action_meter {
> > > > > >   * direction.
> > > > > >   *
> > > > > >   * Multiple flows can be configured to use the same security
> session.
> > > > > > + *
> > > > > > + * The NULL value is allowed for security session. If
> > > > > > + security session is NULL,
> > > > > > + * then SPI field in ESP flow item and IP addresses in flow
> > > > > > + items 'IPv4' and
> > > > > > + * 'IPv6' will be allowed to be a range. The rule thus
> > > > > > + created can enable
> > > > > > + * SECURITY processing on multiple flows.
> 
> What you intent here is " The rule thus created can enable multiple security
> sessions on a single rte flow"
> 
> 
> Regards,
> Akhil