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

[Anoob Joseph <anoobj@marvell.com>]

Hi Vladimir,

Please see inline.

Thanks,
Anoob

> -----Original Message-----
> From: Medvedkin, Vladimir <vladimir.medvedkin@intel.com>
> Sent: Monday, December 16, 2019 9:29 PM
> To: Anoob Joseph <anoobj@marvell.com>; Ananyev, Konstantin
> <konstantin.ananyev@intel.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: [dpdk-dev] [PATCH] ethdev: allow multiple security sessions to
> use one rte flow
> 
> External Email
> 
> ----------------------------------------------------------------------
> Hi Anoob,
> 
> On 11/12/2019 17:33, Anoob Joseph wrote:
> > Hi Konstantin,
> >
> > Please see inline.
> >
> > Thanks,
> > Anoob
> >
> >> -----Original Message-----
> >> From: dev <dev-bounces@dpdk.org> On Behalf Of Ananyev, Konstantin
> >> Sent: Wednesday, December 11, 2019 4:36 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: Re: [dpdk-dev] [PATCH] ethdev: allow multiple security
> >> sessions to use one rte flow
> >>
> >>
> >>>>> 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
> So this means that SA will be indexed only by spi? What about SA's which are
> indexed by SPI+DIP+SIP?
> >>>
> >>> 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.
> If memory is allocated during device configure what is upper limit for number of
> sessions? What if app needs more?
> >
> > 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.

[Anoob] Yes. But we need to allow application to control the h/w ipsec processing as well. Let's say, application wants to handle a specific SPI range in lookaside mode (may be because of unsupported capabilities?), in that case having rte_flow will help in fine tuning how the h/w packet steering happens. Also, rte_flow enables H/w parsing on incoming packets. This info is useful even after IPsec processing is complete. Or if application wants to give higher priority to a range of SPIs, rte_flow would allow doing so. 
 
> What algorithm of indexing by SPI is there? Could I use any arbitrary SPI? If some
> kind of hashing is used, what about collisions?

[Anoob] That is implementation dependent. In our PMD, we map it one to one. As in, SPI is used as index in the table.

> >
> >>> 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
> 
> --
> Regards,
> Vladimir