netdev - RE: [PATCH net v2 2/3] xfrm: Add an activate() offload dev op

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Message-ID: <HE1PR0501MB22358F7859FC35E88D202018B03F0@HE1PR0501MB2235.eurprd05.prod.outlook.com>
Date:   Sun, 3 Dec 2017 11:28:44 +0000
From:   Boris Pismenny <borisp@...lanox.com>
To:     Yossi Kuperman <yossiku@...lanox.com>,
        Steffen Klassert <steffen.klassert@...unet.com>
CC:     Aviv Heller <avivh@...lanox.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Yevgeny Kliteynik <kliteyn@...lanox.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH net v2 2/3] xfrm: Add an activate() offload dev op



> -----Original Message-----
> From: Yossi Kuperman
> Sent: Sunday, December 03, 2017 00:34
> To: Steffen Klassert <steffen.klassert@...unet.com>
> Cc: Aviv Heller <avivh@...lanox.com>; Herbert Xu
> <herbert@...dor.apana.org.au>; Boris Pismenny <borisp@...lanox.com>;
> Yevgeny Kliteynik <kliteyn@...lanox.com>; netdev@...r.kernel.org
> Subject: Re: [PATCH net v2 2/3] xfrm: Add an activate() offload dev op
> 
> 
> 
> >> On 1 Dec 2017, at 9:09, Steffen Klassert <steffen.klassert@...unet.com>
> wrote:
> >>
> >> On Tue, Nov 28, 2017 at 07:55:41PM +0200, avivh@...lanox.com wrote:
> >> From: Aviv Heller <avivh@...lanox.com>
> >>
> >> Adding the state to the offload device prior to replay init in
> >> xfrm_state_construct() will result in NULL dereference if a matching
> >> ESP packet is received in between.
> >>
> >> In order to inhibit driver offload logic from processing the state's
> >> packets prior to the xfrm_state object being completely initialized and
> >> added to the SADBs, a new activate() operation was added to inform the
> >> driver the aforementioned conditions have been met.
> >
> > We discussed this already some time ago, and I still think that
> > we should fix this by setting XFRM_STATE_VALID only after the
> > state is fully initialized.
> 
> An upcoming patch will refactor the if statement (encap_type < 0) in
> xfrm_input, in order to support crypto offload with GRO disabled. Currently it
> doesn’t work. This entails yet another check for the validity of the state.
> Resulting in total of 3 copies: 1) for normal traffic, 2) GRO and 3) crypto offload.
> 
> Anyway, IMO it is not right that we (the driver) allow an incoming packet to be
> delivered while the SA is not yet ready. Rather than checking for an invalid input
> I prefer to make sure that such a case won’t happen in the first place.
> 
> To complete the picture, there is another patch to the driver which simply drop
> incoming packets that underwent successful decryption and haven’t been
> activated yet. Active state merely means that the SA is present in the driver’s
> hash table.
> 
> We can make a separate patch to set the state to valid once it is fully initialized,
> it make sense on its own.
> 
> What do you think?
> 

I would prefer we do not add additional checks in the data-path.
IMO, the SA provided to the driver should be fully initialized.
Do not insert it to HW before it is activated.