xfrm: Introduce xfrm_input_afinfo to access the the callbacks properly

IPv6 can be build as a module, so we need mechanism to access
the address family dependent callback functions properly.
Therefore we introduce xfrm_input_afinfo, similar to that
what we have for the address family dependent part of
policies and states.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

1 files changed, 75 insertions, 0 deletions

diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 4218164f4f5e..85d1d4764612 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -16,6 +16,81 @@
 
 static struct kmem_cache *secpath_cachep __read_mostly;
 
+static DEFINE_SPINLOCK(xfrm_input_afinfo_lock);
+static struct xfrm_input_afinfo __rcu *xfrm_input_afinfo[NPROTO];
+
+int xfrm_input_register_afinfo(struct xfrm_input_afinfo *afinfo)
+{
+	int err = 0;
+
+	if (unlikely(afinfo == NULL))
+		return -EINVAL;
+	if (unlikely(afinfo->family >= NPROTO))
+		return -EAFNOSUPPORT;
+	spin_lock_bh(&xfrm_input_afinfo_lock);
+	if (unlikely(xfrm_input_afinfo[afinfo->family] != NULL))
+		err = -ENOBUFS;
+	else
+		rcu_assign_pointer(xfrm_input_afinfo[afinfo->family], afinfo);
+	spin_unlock_bh(&xfrm_input_afinfo_lock);
+	return err;
+}
+EXPORT_SYMBOL(xfrm_input_register_afinfo);
+
+int xfrm_input_unregister_afinfo(struct xfrm_input_afinfo *afinfo)
+{
+	int err = 0;
+
+	if (unlikely(afinfo == NULL))
+		return -EINVAL;
+	if (unlikely(afinfo->family >= NPROTO))
+		return -EAFNOSUPPORT;
+	spin_lock_bh(&xfrm_input_afinfo_lock);
+	if (likely(xfrm_input_afinfo[afinfo->family] != NULL)) {
+		if (unlikely(xfrm_input_afinfo[afinfo->family] != afinfo))
+			err = -EINVAL;
+		else
+			RCU_INIT_POINTER(xfrm_input_afinfo[afinfo->family], NULL);
+	}
+	spin_unlock_bh(&xfrm_input_afinfo_lock);
+	synchronize_rcu();
+	return err;
+}
+EXPORT_SYMBOL(xfrm_input_unregister_afinfo);
+
+static struct xfrm_input_afinfo *xfrm_input_get_afinfo(unsigned int family)
+{
+	struct xfrm_input_afinfo *afinfo;
+
+	if (unlikely(family >= NPROTO))
+		return NULL;
+	rcu_read_lock();
+	afinfo = rcu_dereference(xfrm_input_afinfo[family]);
+	if (unlikely(!afinfo))
+		rcu_read_unlock();
+	return afinfo;
+}
+
+static void xfrm_input_put_afinfo(struct xfrm_input_afinfo *afinfo)
+{
+	rcu_read_unlock();
+}
+
+static int xfrm_rcv_cb(struct sk_buff *skb, unsigned int family, u8 protocol,
+		       int err)
+{
+	int ret;
+	struct xfrm_input_afinfo *afinfo = xfrm_input_get_afinfo(family);
+
+	if (!afinfo)
+		return -EAFNOSUPPORT;
+
+	ret = afinfo->callback(skb, protocol, err);
+	xfrm_input_put_afinfo(afinfo);
+
+	return ret;
+}
+
 void __secpath_destroy(struct sec_path *sp)
 {
 	int i;