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

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Date:   Fri, 1 Dec 2017 11:47:12 -0800
From:   Shannon Nelson <shannon.nelson@...cle.com>
To:     avivh@...lanox.com, Steffen Klassert <steffen.klassert@...unet.com>
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        Boris Pismenny <borisp@...lanox.com>,
        Yossi Kuperman <yossiku@...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 11/28/2017 9:55 AM, 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.

Are there also conditions where you would want to temporarily 
deactivate, or pause, the incoming driver offload, followed then by 
another activate?

sln

> 
> Signed-off-by: Aviv Heller <avivh@...lanox.com>
> Signed-off-by: Yossi Kuperman <yossiku@...lanox.com>
> ---
> v1 -> v2:
> 	- Separate to state addition and then activation, instead
> 	  of relocating dev state addition call.
> ---
>   include/linux/netdevice.h |  1 +
>   include/net/xfrm.h        | 12 ++++++++++++
>   net/xfrm/xfrm_user.c      |  5 +++++
>   3 files changed, 18 insertions(+)
> 
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 2eaac7d..c6ca356 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -819,6 +819,7 @@ struct netdev_xdp {
>   #ifdef CONFIG_XFRM_OFFLOAD
>   struct xfrmdev_ops {
>   	int	(*xdo_dev_state_add) (struct xfrm_state *x);
> +	void	(*xdo_dev_state_activate) (struct xfrm_state *x);
>   	void	(*xdo_dev_state_delete) (struct xfrm_state *x);
>   	void	(*xdo_dev_state_free) (struct xfrm_state *x);
>   	bool	(*xdo_dev_offload_ok) (struct sk_buff *skb,
> diff --git a/include/net/xfrm.h b/include/net/xfrm.h
> index e015e16..324374e 100644
> --- a/include/net/xfrm.h
> +++ b/include/net/xfrm.h
> @@ -1877,6 +1877,14 @@ static inline bool xfrm_dst_offload_ok(struct dst_entry *dst)
>   	return false;
>   }
>   
> +static inline void xfrm_dev_state_activate(struct xfrm_state *x)
> +{
> +	struct xfrm_state_offload *xso = &x->xso;
> +
> +	if (xso->dev && xso->dev->xfrmdev_ops->xdo_dev_state_activate)
> +		xso->dev->xfrmdev_ops->xdo_dev_state_activate(x);
> +}
> +
>   static inline void xfrm_dev_state_delete(struct xfrm_state *x)
>   {
>   	struct xfrm_state_offload *xso = &x->xso;
> @@ -1907,6 +1915,10 @@ static inline int xfrm_dev_state_add(struct net *net, struct xfrm_state *x, stru
>   	return 0;
>   }
>   
> +static inline void xfrm_dev_state_activate(struct xfrm_state *x)
> +{
> +}
> +
>   static inline void xfrm_dev_state_delete(struct xfrm_state *x)
>   {
>   }
> diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
> index e44a0fe..d06f579 100644
> --- a/net/xfrm/xfrm_user.c
> +++ b/net/xfrm/xfrm_user.c
> @@ -662,6 +662,11 @@ static int xfrm_add_sa(struct sk_buff *skb, struct nlmsghdr *nlh,
>   		goto out;
>   	}
>   
> +	spin_lock_bh(&x->lock);
> +	if (x->km.state == XFRM_STATE_VALID)
> +		xfrm_dev_state_activate(x);
> +	spin_unlock_bh(&x->lock);
> +
>   	c.seq = nlh->nlmsg_seq;
>   	c.portid = nlh->nlmsg_pid;
>   	c.event = nlh->nlmsg_type;
>