xfrm: add is_ipip to struct xfrm_input_afinfo

This patch is to add a new member is_ipip to struct xfrm_input_afinfo,
to allow another group family of callback functions to be registered
with is_ipip set.

This will be used for doing a callback for struct xfrm(6)_tunnel of
ipip/ipv6 tunnels in xfrm_input() by calling xfrm_rcv_cb(), which is
needed by ipip/ipv6 tunnels' support in ip(6)_vti and xfrm interface
in the next patches.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>

include/net/xfrm.h

@@ -373,7 +373,8 @@ struct xfrm_state_afinfo *xfrm_state_get_afinfo(unsigned int family);
 struct xfrm_state_afinfo *xfrm_state_afinfo_get_rcu(unsigned int family);
 
 struct xfrm_input_afinfo {
-	unsigned int		family;
+	u8			family;
+	bool			is_ipip;
 	int			(*callback)(struct sk_buff *skb, u8 protocol,
 					    int err);
 };

net/xfrm/xfrm_input.c

@@ -42,7 +42,7 @@ struct xfrm_trans_cb {
 #define XFRM_TRANS_SKB_CB(__skb) ((struct xfrm_trans_cb *)&((__skb)->cb[0]))
 
 static DEFINE_SPINLOCK(xfrm_input_afinfo_lock);
-static struct xfrm_input_afinfo const __rcu *xfrm_input_afinfo[AF_INET6 + 1];
+static struct xfrm_input_afinfo const __rcu *xfrm_input_afinfo[2][AF_INET6 + 1];
 
 static struct gro_cells gro_cells;
 static struct net_device xfrm_napi_dev;
@@ -53,14 +53,14 @@ int xfrm_input_register_afinfo(const struct xfrm_input_afinfo *afinfo)
 {
 	int err = 0;
 
-	if (WARN_ON(afinfo->family >= ARRAY_SIZE(xfrm_input_afinfo)))
+	if (WARN_ON(afinfo->family > AF_INET6))
 		return -EAFNOSUPPORT;
 
 	spin_lock_bh(&xfrm_input_afinfo_lock);
-	if (unlikely(xfrm_input_afinfo[afinfo->family] != NULL))
+	if (unlikely(xfrm_input_afinfo[afinfo->is_ipip][afinfo->family]))
 		err = -EEXIST;
 	else
-		rcu_assign_pointer(xfrm_input_afinfo[afinfo->family], afinfo);
+		rcu_assign_pointer(xfrm_input_afinfo[afinfo->is_ipip][afinfo->family], afinfo);
 	spin_unlock_bh(&xfrm_input_afinfo_lock);
 	return err;
 }
@@ -71,11 +71,11 @@ int xfrm_input_unregister_afinfo(const struct xfrm_input_afinfo *afinfo)
 	int err = 0;
 
 	spin_lock_bh(&xfrm_input_afinfo_lock);
-	if (likely(xfrm_input_afinfo[afinfo->family] != NULL)) {
-		if (unlikely(xfrm_input_afinfo[afinfo->family] != afinfo))
+	if (likely(xfrm_input_afinfo[afinfo->is_ipip][afinfo->family])) {
+		if (unlikely(xfrm_input_afinfo[afinfo->is_ipip][afinfo->family] != afinfo))
 			err = -EINVAL;
 		else
-			RCU_INIT_POINTER(xfrm_input_afinfo[afinfo->family], NULL);
+			RCU_INIT_POINTER(xfrm_input_afinfo[afinfo->is_ipip][afinfo->family], NULL);
 	}
 	spin_unlock_bh(&xfrm_input_afinfo_lock);
 	synchronize_rcu();
@@ -83,15 +83,15 @@ int xfrm_input_unregister_afinfo(const struct xfrm_input_afinfo *afinfo)
 }
 EXPORT_SYMBOL(xfrm_input_unregister_afinfo);
 
-static const struct xfrm_input_afinfo *xfrm_input_get_afinfo(unsigned int family)
+static const struct xfrm_input_afinfo *xfrm_input_get_afinfo(u8 family, bool is_ipip)
 {
 	const struct xfrm_input_afinfo *afinfo;
 
-	if (WARN_ON_ONCE(family >= ARRAY_SIZE(xfrm_input_afinfo)))
+	if (WARN_ON_ONCE(family > AF_INET6))
 		return NULL;
 
 	rcu_read_lock();
-	afinfo = rcu_dereference(xfrm_input_afinfo[family]);
+	afinfo = rcu_dereference(xfrm_input_afinfo[is_ipip][family]);
 	if (unlikely(!afinfo))
 		rcu_read_unlock();
 	return afinfo;
@@ -100,9 +100,11 @@ static const struct xfrm_input_afinfo *xfrm_input_get_afinfo(unsigned int family
 static int xfrm_rcv_cb(struct sk_buff *skb, unsigned int family, u8 protocol,
 		       int err)
 {
+	bool is_ipip = (protocol == IPPROTO_IPIP || protocol == IPPROTO_IPV6);
+	const struct xfrm_input_afinfo *afinfo;
 	int ret;
-	const struct xfrm_input_afinfo *afinfo = xfrm_input_get_afinfo(family);
 
+	afinfo = xfrm_input_get_afinfo(family, is_ipip);
 	if (!afinfo)
 		return -EAFNOSUPPORT;