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Message-ID: <B8CEC0B8-8A38-40A2-A1F1-F8967D2ACCC2@mellanox.com>
Date: Wed, 10 Jan 2018 23:09:00 +0000
From: Yossi Kuperman <yossiku@...lanox.com>
To: Shannon Nelson <shannon.nelson@...cle.com>
CC: Yossef Efraim <yossefe@...lanox.com>,
Jonathan Corbet <corbet@....net>,
"David S. Miller" <davem@...emloft.net>,
Steffen Klassert <steffen.klassert@...unet.com>,
Herbert Xu <herbert@...dor.apana.org.au>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
Boris Pismenny <borisp@...lanox.com>,
Yevgeny Kliteynik <kliteyn@...lanox.com>
Subject: Re: [PATCH net-next v2] xfrm: Add ESN support for IPSec HW offload
> On 10 Jan 2018, at 19:36, Shannon Nelson <shannon.nelson@...cle.com> wrote:
>
>> On 1/10/2018 2:34 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>
>> ---
>> Changes from v1:
>> - Added documentation
>> ---
>> Documentation/networking/xfrm_device.txt | 3 +++
>> include/linux/netdevice.h | 1 +
>> include/net/xfrm.h | 12 ++++++++++++
>> net/xfrm/xfrm_device.c | 4 ++--
>> net/xfrm/xfrm_replay.c | 2 ++
>> 5 files changed, 20 insertions(+), 2 deletions(-)
>> diff --git a/Documentation/networking/xfrm_device.txt b/Documentation/networking/xfrm_device.txt
>> index 2d9d588c..50c34ca 100644
>> --- a/Documentation/networking/xfrm_device.txt
>> +++ b/Documentation/networking/xfrm_device.txt
>> @@ -41,6 +41,7 @@ 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);
>> };
>> The NIC driver offering ipsec offload will need to implement these
>> @@ -117,6 +118,8 @@ the stack in xfrm_input().
>> hand the packet to napi_gro_receive() as usual
>> +In ESN mode, xdo_dev_state_advance_esn() is called from xfrm_replay_advance_esn().
>> +Driver will check packet seq number and update HW ESN state machine if needed.
>> When the SA is removed by the user, the driver's xdo_dev_state_delete()
>> is asked to disable the offload. Later, xdo_dev_state_free() is called
>> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
>> index 352066e..3c81cd7 100644
>> --- a/include/linux/netdevice.h
>> +++ b/include/linux/netdevice.h
>> @@ -842,6 +842,7 @@ 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 079ea94..1ca2e6e 100644
>> --- a/include/net/xfrm.h
>> +++ b/include/net/xfrm.h
>> @@ -1901,6 +1901,14 @@ 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);
>> +}
>> +
>> static inline bool xfrm_dst_offload_ok(struct dst_entry *dst)
>> {
>> struct xfrm_state *x = dst->xfrm;
>> @@ -1971,6 +1979,10 @@ 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 7598250..704a055 100644
>> --- a/net/xfrm/xfrm_device.c
>> +++ b/net/xfrm/xfrm_device.c
>> @@ -147,8 +147,8 @@ 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)
>
> As I mentioned before, this will cause issues when working with hardware that has no ESN support, such as Intel's x540: the stack will expect the driver to do ESN, and nothing actually happens but a rollover of the numbers. Sure, the driver could look for the ESN attribute and fail the add, but that's a mode where we have to update every driver to fend off problems every time we add a new feature. Much better is to only update drivers that actively support the new feature.
>
You are right.
I’m not sure why this check is here in the first place. IMO it should take place in xdo_dev_state_add—a driver-specific callback.
What do you suggest?
> Look at how feature bits are added to netdev->features to signify what the driver can do. I think that's a much better approach.
>
It looks like an overkill?
> sln
>
>
>> return -EINVAL;
>> 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);
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