ip_gre: fix ipgre_header to return correct offset

Fix ipgre_header() (header_ops->create) to return the correct
amount of bytes pushed. Most callers of dev_hard_header() seem
to care only if it was success, but af_packet.c uses it as
offset to the skb to copy from userspace only once. In practice
this fixes packet socket sendto()/sendmsg() to gre tunnels.

Regression introduced in c54419321455631079c7d6e60bc732dd0c5914c5
("GRE: Refactor GRE tunneling code.")

Cc: Pravin B Shelar <[email protected]>
Signed-off-by: Timo Teräs <[email protected]>
Acked-by: Eric Dumazet <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index 1f6eab66f7cee5f94e1a5cfd6b6ea919184b5d35..8d6939eeb49247b1c2ee8659cc190814d64eb4e5 100644 (file)
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -383,7 +383,7 @@ static int ipgre_header(struct sk_buff *skb, struct net_device *dev,
        if (daddr)
                memcpy(&iph->daddr, daddr, 4);
        if (iph->daddr)
-               return t->hlen;
+               return t->hlen + sizeof(*iph);
 
        return -(t->hlen + sizeof(*iph));
 }