Re: [dpdk-dev] [PATCH 2/3] cryptodev: add security operation to crypto operation

[Akhil Goyal <akhil.goyal@nxp.com>]

Hi Konstantin/David,

> 
> Hi David,
> 
> > > > >
> > > > > >
> > > > > >  /** Status of crypto operation */ @@ -121,6 +123,13 @@ struct
> > > > > > rte_crypto_op {
> > > > > >  		struct rte_crypto_asym_op asym[0];
> > > > > >  		/**< Asymmetric operation parameters */
> > > > > >
> > > > > > +#ifdef RTE_LIBRTE_SECURITY
> > > > > > +		uint8_t security[0];
> > > > > > +		/**< Security operation parameters
> > > > > > +		 * - Must be accessed through a rte_security_op pointer
> > > > > > +		 */
> > > > > > +#endif
> > > > > > +
> > > > > >  	}; /**< operation specific parameters */  };
> > > > >
> > > > > Is there any point to have this extra level of indirection?
> > > > > Might be simply:
> > > > >
> > > > > enum rte_crypto_op_type {
> > > > > 	....
> > > > > +	RTE_CRYPTO_OP_TYPE_SEC_DOCSIS,
> > > > > };
> > > > > ...
> > > > > struct rte_crypto_op {
> > > > > 	....
> > > > > 	__extension__
> > > > >         union {
> > > > >                 struct rte_crypto_sym_op sym[0];
> > > > >                 /**< Symmetric operation parameters */
> > > > >
> > > > >                 struct rte_crypto_asym_op asym[0];
> > > > >                 /**< Asymmetric operation parameters */
> > > > >
> > > > > +	struct rte_security_docsis_op docsis[0];
> > > > >
> > > > >         }; /**< operation specific parameters */
> > > > >
> > > > > ?
> > > > [DC] This was to allow some form of extensibility and not to limit this to
> just
> > > DOCSIS.
> > > > If it's felt that having the extra level of indirection is overkill, it can be easily
> > > changed.
> > > >
> > > > However, we cannot include a struct of type 'struct
> > > > rte_security_docsis_op' (or 'struct rte_security_op') directly here,
> > > > without creating nasty circular dependency of includes between
> > > rte_cryptodev and rte_security.
> > > >
> > > > I had tried defining an opaque version 'struct rte_security_op' (i.e.
> > > > no fields within the struct) here in rte_crypto.h, but the compiler
> > > > complained that it couldn't determine the size of the struct, even though
> > > it's a zero length array.
> > > >
> > > > That is why I had to use the uint8_t in 'uint8_t security[0];' - I
> > > > don't like this, but I couldn't find another way that kept the compiler happy
> > > and didn't create a circular dependency.
> > >
> > > I see... would it be an option to name this struct 'struct rte_sym_docsis_op
> > > and and move actual definition inside
> > > lib/librte_cryptodev/rte_crypto_sym.h?
> > >
> > [DC] It's certainly an option and would work but I don't think it's a good idea to
> be putting
> > protocol specific structs like this in rte_cryptodev - that's what rte_security is
> for.
> > Do you think it would be ok to do this?
> 
> I personally don't see a problem with this.
> In fact, as an extra  thought - why we can't have docsis xform defined in
> lib/librte_cryptodev/rte_crypto_sym.h too, and then just have it  as a member
> inside struct rte_crypto_sym_xform union?
> Then we can have rte_cryptodev_sym_session that supports docsis stuff.

Adding DOCSIS alone is not an issue in the cryptodev. The intent of this patchset and 
Previous RFCs was chaining of two - DOCSIS and CRC which are supposed to be separate
Blocks and we need a way to combine the two and use it in the application.
rte_security provides a way to handle such protocols for algo combinations. 
However, IMO we do not really need a separate rte_security_docsis_op structure,
As it has parameters which are already there in the rte_crypto_sym_op. This new op
Struct is just adding extra bytes which can be avoided if we use sym_op->auth.data.offset 
And sym_op->auth.data.length in place of crc offset and crc length.
We may just need to add comment in the struct definition about its usage for CRC cases.

> 
> >
> > I'd be interested to hear what cryptodev/security maintainers and others think
> too.
> > Akhil/Declan - any thoughts on best approach here?