[RFC bpf-next 2/7] net: introduce skb_net helper

[Stanislav Fomichev <sdf@google.com>]

skb_net returns network namespace from the associated device or socket.

This will be used in the next commit.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 include/linux/skbuff.h |  2 ++
 net/core/skbuff.c      | 10 ++++++++++
 2 files changed, 12 insertions(+)

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index ad883ab2762c..28723a86efdf 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -4343,5 +4343,7 @@ static inline __wsum lco_csum(struct sk_buff *skb)
 	return csum_partial(l4_hdr, csum_start - l4_hdr, partial);
 }
 
+struct net *skb_net(const struct sk_buff *skb);
+
 #endif	/* __KERNEL__ */
 #endif	/* _LINUX_SKBUFF_H */
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 23c9cf100bd4..016db13fa2b6 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -5585,6 +5585,16 @@ void skb_condense(struct sk_buff *skb)
 	skb->truesize = SKB_TRUESIZE(skb_end_offset(skb));
 }
 
+struct net *skb_net(const struct sk_buff *skb)
+{
+	if (skb->dev)
+		return dev_net(skb->dev);
+	else if (skb->sk)
+		return sock_net(skb->sk);
+	return NULL;
+}
+EXPORT_SYMBOL(skb_net);
+
 #ifdef CONFIG_SKB_EXTENSIONS
 static void *skb_ext_get_ptr(struct skb_ext *ext, enum skb_ext_id id)
 {
-- 
2.20.1.611.gfbb209baf1-goog