netdev - RE: [PATCH net-next 3/3] xfrm: Add ESN support for IPSec HW offload

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Date:   Wed, 10 Jan 2018 11:37:09 +0000
From:   Yossef Efraim <yossefe@...lanox.com>
To:     Shannon Nelson <shannon.nelson@...cle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Boris Pismenny <borisp@...lanox.com>,
        Yevgeny Kliteynik <kliteyn@...lanox.com>,
        Yossi Kuperman <yossiku@...lanox.com>
Subject: RE: [PATCH net-next 3/3] xfrm: Add ESN support for IPSec HW offload

> On 11/28/2017 1:49 AM, yossefe@...lanox.com wrote:
> > From: Yossef Efraim <yossefe@...lanox.com>
> >
> > This patch adds ESN support to IPsec device offload.
> > Adding new xfrm device operation to synchronize device ESN.
> >
> > Signed-off-by: Yossef Efraim <yossefe@...lanox.com>
> > ---
> >   include/linux/netdevice.h |  1 +
> >   include/net/xfrm.h        | 12 ++++++++++++
> >   net/xfrm/xfrm_device.c    |  4 ++--
> >   net/xfrm/xfrm_replay.c    |  2 ++
> >   4 files changed, 17 insertions(+), 2 deletions(-)
> >
> > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> > index 7de7656..d4e9198 100644
> > --- a/include/linux/netdevice.h
> > +++ b/include/linux/netdevice.h
> > @@ -825,6 +825,7 @@ struct xfrmdev_ops {
> >   	void	(*xdo_dev_state_free) (struct xfrm_state *x);
> >   	bool	(*xdo_dev_offload_ok) (struct sk_buff *skb,
> >   				       struct xfrm_state *x);
> > +	void	(*xdo_dev_state_advance_esn) (struct xfrm_state *x);
> >   };
> >   #endif
> >
> > diff --git a/include/net/xfrm.h b/include/net/xfrm.h index
> > dc28a98..372bfcb 100644
> > --- a/include/net/xfrm.h
> > +++ b/include/net/xfrm.h
> > @@ -1863,6 +1863,14 @@ int xfrm_dev_state_add(struct net *net, struct
> xfrm_state *x,
> >   		       struct xfrm_user_offload *xuo);
> >   bool xfrm_dev_offload_ok(struct sk_buff *skb, struct xfrm_state *x);
> >
> > +static inline void xfrm_dev_state_advance_esn(struct xfrm_state *x) {
> > +	struct xfrm_state_offload *xso = &x->xso;
> > +
> > +	if (xso->dev && xso->dev->xfrmdev_ops->xdo_dev_state_advance_esn)
> > +		xso->dev->xfrmdev_ops->xdo_dev_state_advance_esn(x);
> 
> If there isn't an implementation for xdo_dev_state_advance_esn, should this
> even have been called?  See my comment below about checking the
> XFRM_STATE_ESN.
>

Thanks for the input , answered below
 
> What is the driver expected to do with this?  I would guess that maybe the
> hardware doing the offload needs to know when the ESN is advanced so that it
> can change the ICV calculation accordingly, but that only is useful for hardware
> that knows about ESN.
>

The driver checks packet seq number and sets ESN state machine accordingly.
Meaning it will increase ESN HW counter when needed.
We are submitting driver code now, so you review it
 
> > +}
> > +
> >   static inline bool xfrm_dst_offload_ok(struct dst_entry *dst)
> >   {
> >   	struct xfrm_state *x = dst->xfrm;
> > @@ -1920,6 +1928,10 @@ static inline bool xfrm_dev_offload_ok(struct
> sk_buff *skb, struct xfrm_state *x
> >   	return false;
> >   }
> >
> > +static inline void xfrm_dev_state_advance_esn(struct xfrm_state *x) {
> > +}
> > +
> >   static inline bool xfrm_dst_offload_ok(struct dst_entry *dst)
> >   {
> >   	return false;
> > diff --git a/net/xfrm/xfrm_device.c b/net/xfrm/xfrm_device.c index
> > dc68d9c..fc7e1e44 100644
> > --- a/net/xfrm/xfrm_device.c
> > +++ b/net/xfrm/xfrm_device.c
> > @@ -65,8 +65,8 @@ int xfrm_dev_state_add(struct net *net, struct
> xfrm_state *x,
> >   	if (!x->type_offload)
> >   		return -EINVAL;
> >
> > -	/* We don't yet support UDP encapsulation, TFC padding and ESN. */
> > -	if (x->encap || x->tfcpad || (x->props.flags & XFRM_STATE_ESN))
> > +	/* We don't yet support UDP encapsulation and TFC padding. */
> > +	if (x->encap || x->tfcpad)
> >   		return -EINVAL;
> 
> Maybe we should check to see that xdo_dev_state_advance_esn is
> implemented before allowing XFRM_STATE_ESN?
> 
> sln
> 

We thought about adding some kind of capability queries (same goes for udp encap and tcf padding) while we wrote this feature.
This is possible but out of this patch set scope as it is general.
Steffen - your thoughts ?

> >
> >   	dev = dev_get_by_index(net, xuo->ifindex); diff --git
> > a/net/xfrm/xfrm_replay.c b/net/xfrm/xfrm_replay.c index
> > 0250181..1d38c6a 100644
> > --- a/net/xfrm/xfrm_replay.c
> > +++ b/net/xfrm/xfrm_replay.c
> > @@ -551,6 +551,8 @@ static void xfrm_replay_advance_esn(struct
> xfrm_state *x, __be32 net_seq)
> >   			bitnr = replay_esn->replay_window - (diff - pos);
> >   	}
> >
> > +	xfrm_dev_state_advance_esn(x);
> > +
> >   	nr = bitnr >> 5;
> >   	bitnr = bitnr & 0x1F;
> >   	replay_esn->bmp[nr] |= (1U << bitnr);
> >