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

[Ananyev, Konstantin]

> > > > > > > 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?
> > >
> > > [Anoob] I'm not sure what exactly you meant by user. But may be I'll explain
> > how it's done in OCTEONTX2 PMD.
> > >
> > > The application would create security_session for every SA. SPI etc would be
> > available to PMD (in conf) when the session is created.
> > > Now the PMD would populate SA related params in a specific location
> > > that h/w would access. This memory is allocated during device configure and
> > h/w would have the pointer after the initialization is done.
> > >
> > > PMD uses SPI as index to write into specific locations(during session
> > > create) and h/w would use it when it sees an ESP packet eligible for
> > > SECURITY (in receive path, per packet). As long as session creation could
> > populate at memory locations that h/w would look at, this scheme would work.
> >
> > Thanks for explanation, few more questions:
> > Ok, so the table will be allocated at device init() somehow (nothing to do with
> > rte_flow).
> 
> [Anoob] Yes.
> 
> > Then PMD will be able to write/update entries in that table and HW will be able
> > to read (to get SPI, keys, etc), correct?
> 
> [Anoob] Yes.
> 
> > Now if upper layer (ipsec-secgw for example) would like to create new ESP
> > session on that device, what it would need to do?
> > Would it still need to use rte_flow API for that?
> > Or just call rte_security_session_create() and PMD will take update this HW/SW
> > table for it?
> 
> [Anoob] rte_security_session_create() is enough.

Then probably a stupid question: 
If this HW/SW table will be created at dev_init() and to populate it
rte_security_session_create() is sufficient,  
why do you need that dummy flow at all?
Would it be just used as a switch to enable/disable HW IPsec packet processing
(either per whole device, or for some sub-ranges of SPI/SIP/DIP)?
Something different?
Konstantin 

> 
> >
> > >
> > > >
> > > > >
> > > > > 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 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 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