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

[Anoob Joseph <anoobj@marvell.com>]

Hi Konstantin,

Please see inline.

Thanks,
Anoob

> -----Original Message-----
> From: Ananyev, Konstantin <konstantin.ananyev@intel.com>
> Sent: Monday, December 16, 2019 6:24 PM
> To: Anoob Joseph <anoobj@marvell.com>; Akhil Goyal <akhil.goyal@nxp.com>;
> Adrien Mazarguil <adrien.mazarguil@6wind.com>; Doherty, Declan
> <declan.doherty@intel.com>; Yigit, Ferruh <ferruh.yigit@intel.com>; Jerin Jacob
> Kollanukkaran <jerinj@marvell.com>; Thomas Monjalon
> <thomas@monjalon.net>
> Cc: Ankur Dwivedi <adwivedi@marvell.com>; Hemant Agrawal
> <hemant.agrawal@nxp.com>; Matan Azrad <matan@mellanox.com>; Nicolau,
> Radu <radu.nicolau@intel.com>; Shahaf Shuler <shahafs@mellanox.com>;
> Narayana Prasad Raju Athreya <pathreya@marvell.com>; dev@dpdk.org
> Subject: [EXT] RE: [PATCH] ethdev: allow multiple security sessions to use one
> rte flow
> 
> External Email
> 
> ----------------------------------------------------------------------
> 
> > > > > > > > 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?

[Anoob] Your understanding is correct. rte_flow is used to selectively enable/disable HW IPsec processing. 
 
> 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@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