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

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

> > >
> > > 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.
> >
> > Wonder what will be the usage model for it?
> > AFAIK,  RFC 4301 clearly states that either SPI value alone or in conjunction with
> > dst (and src) IP should clearly identify SA for inbound SAD lookup.
> > Am I missing something obvious here?
> 
> [Anoob] Existing SECURITY action type requires application to create an 'rte_flow' per SA, which is not really required if h/w can use SPI to
> uniquely identify the security session/SA.
> 
> Existing rte_flow usage: IP (dst,src) + ESP + SPI -> security processing enabled on one security session (ie on SA)
> 
> The above rule would uniquely identify packets for an SA. But with the above usage, we would quickly exhaust entries available in h/w
> lookup tables (which are limited on our hardware). But if h/w can use SPI field to index into a table (for example), then the above
> requirement of one rte_flow per SA is not required.
> 
> Proposed rte_flow usage: IP (any) + ESP + SPI (any) -> security processing enabled on all ESP packets
> 
> Now h/w could use SPI to index into a pre-populated table to get security session. Please do note that, SPI is not ignored during the actual
> lookup. Just that it is not used while creating 'rte_flow'.

And this table will be prepopulated by user and pointer to it will be somehow passed via rte_flow API?
If yes, then what would be the mechanism? 

> 
> The usage of one 'rte_flow' for multiple SAs is not mandatory. It is only required when application requires large number of SAs. The
> proposed change is to allow more efficient usage of h/w resources where it's permitted by the PMD.
> 
> >
> > >
> > > 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 452d359..21fa7ed 100644
> > > --- a/lib/librte_ethdev/rte_flow.h
> > > +++ b/lib/librte_ethdev/rte_flow.h
> > > @@ -2239,6 +2239,12 @@ 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