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

Akhil Goyal akhil.goyal at nxp.com
Mon Aug 19 09:09:17 CEST 2019


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?

Inline proto case is not using rte_flow at the moment.
And as far as I understand, you also do not need rte_flow to be configured.
Inline crypto cases are mainly for Intel and Mellanox cases which only supported
Inline crypto. For Protocol offload cases, I don't feel we need rte_flow as all information
related to ipsec is already there when we call the session create. Rte_flows are used
For segregation of ethernet traffic for classification which can be configured for various factors
as well.

> 
> >
> > 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.

Why do you need that flow as well. You have all the information in the session already.
You can process the packets based on that information. Isn't it?
Current implementation in application is good enough in my opinion.

> 
> > 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?

As of now I do not have any comment on this. We are not using rte_flow in our work as of now.
It is kind of POC for us, we may not upstream it.
This will depend on the changes that will be done.

> 
> >
> > >
> > > >
> > > > > > >
> > > > > > > Application should do an rte_flow_validate() to make sure the
> > > > > > > flow is supported on the PMD.
> > > > > > >
> > > > > > > Signed-off-by: Anoob Joseph <anoobj at 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


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