[PATCH 1/4 nf-next v2] netfilter: conntrack: add nf_ct_get_or_find() helper

[Fernando Fernandez Mancera <fmancera@suse.de>]

Introduce a helper function which tries to get a ct, if it is a
template, then the tuple pointer from the skb and perform a lookup to
find the actual ct.

A refcounted bool parameter must be passed in order to know if the
caller need to call nf_ct_put() after it is done using the ct.

Signed-off-by: Fernando Fernandez Mancera <fmancera@suse.de>
---
v2: added this commit to the series
---
 include/net/netfilter/nf_conntrack.h |  3 +++
 net/netfilter/nf_conntrack_core.c    | 35 ++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index aa0a7c82199e..5a0dd5715122 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -201,6 +201,9 @@ bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
 		       u_int16_t l3num, struct net *net,
 		       struct nf_conntrack_tuple *tuple);
 
+struct nf_conn *nf_ct_get_or_find(struct net *net, const struct sk_buff *skb,
+				  u16 l3num, bool *refcounted);
+
 void __nf_ct_refresh_acct(struct nf_conn *ct, enum ip_conntrack_info ctinfo,
 			  u32 extra_jiffies, unsigned int bytes);
 
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 0b95f226f211..3ef152a378cc 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -428,6 +428,41 @@ bool nf_ct_get_tuplepr(const struct sk_buff *skb, unsigned int nhoff,
 }
 EXPORT_SYMBOL_GPL(nf_ct_get_tuplepr);
 
+struct nf_conn *
+nf_ct_get_or_find(struct net *net, const struct sk_buff *skb, u16 l3num,
+		  bool *refcounted)
+{
+	const struct nf_conntrack_tuple_hash *h;
+	const struct nf_conntrack_zone *zone;
+	struct nf_conntrack_tuple tuple;
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct;
+
+	ct = nf_ct_get(skb, &ctinfo);
+	if (ct && !nf_ct_is_template(ct))
+		return ct;
+
+	if (!nf_ct_get_tuplepr(skb, skb_network_offset(skb), l3num, net, &tuple))
+		return NULL;
+
+	if (ct)
+		zone = nf_ct_zone(ct);
+	else
+		zone = &nf_ct_zone_dflt;
+
+	h = nf_conntrack_find_get(net, zone, &tuple);
+	if (!h)
+		return NULL;
+
+	ct = nf_ct_tuplehash_to_ctrack(h);
+
+	/* refcount increased, nf_ct_put() is needed after done with it */
+	*refcounted = true;
+
+	return ct;
+}
+EXPORT_SYMBOL_GPL(nf_ct_get_or_find);
+
 bool
 nf_ct_invert_tuple(struct nf_conntrack_tuple *inverse,
 		   const struct nf_conntrack_tuple *orig)
-- 
2.51.0