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

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

Hi Anoob,

> 
> > > > >
> > > > > 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.
> 
> 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.
> 
> 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.

QQ: Would that change be accompanied with real implementation for some particular PMD?
Konstantin


> 
> >
> > > > >
> > > > > 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.
> > > > > + *
> > > > >   */
> > > > >  struct rte_flow_action_security {
> > > > >  	void *security_session; /**< Pointer to security session structure.
> > > > > */
> > > > > --
> > > > > 2.7.4