xfrm: Add ESN support for IPSec HW offload

This patch adds ESN support to IPsec device offload.
Adding new xfrm device operation to synchronize device ESN.
Signed-off-by: Yossef Efraim <yossefe@mellanox.com>
Signed-off-by: Shannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

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

include/linux/netdevice.h

@@ -851,6 +851,7 @@ 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
 

include/net/xfrm.h

@@ -1904,6 +1904,14 @@ 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;
@@ -1974,6 +1982,10 @@ 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;

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)
 		return -EINVAL;
 
 	dev = dev_get_by_index(net, xuo->ifindex);
@@ -178,6 +178,13 @@ int xfrm_dev_state_add(struct net *net, struct xfrm_state *x,
 		return 0;
 	}
 
+	if (x->props.flags & XFRM_STATE_ESN &&
+	    !dev->xfrmdev_ops->xdo_dev_state_advance_esn) {
+		xso->dev = NULL;
+		dev_put(dev);
+		return -EINVAL;
+	}
+
 	xso->dev = dev;
 	xso->num_exthdrs = 1;
 	xso->flags = xuo->flags;

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);