udp6: fix UDP/IPv6 encap resubmit path

IPv4 interprets a negative return value from a protocol handler as a
request to redispatch to a new protocol.  In contrast, IPv6 interprets a
negative value as an error, and interprets a positive value as a request
for redispatch.

UDP for IPv6 was unaware of this difference.  Change __udp6_lib_rcv() to
return a positive value for redispatch.  Note that the socket's
encap_rcv hook still needs to return a negative value to request
dispatch, and in the case of IPv6 packets, adjust IP6CB(skb)->nhoff to
identify the byte containing the next protocol.

Signed-off-by: Bill Sommerfeld <wsommerfeld@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 22e28a44e3c88c6e52ff59ea1c7dd8a3e964e701..422dd014aa2ce9b27263eed4612ff156271d982f 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -962,11 +962,9 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
                ret = udpv6_queue_rcv_skb(sk, skb);
                sock_put(sk);
 
-               /* a return value > 0 means to resubmit the input, but
-                * it wants the return to be -protocol, or 0
-                */
+               /* a return value > 0 means to resubmit the input */
                if (ret > 0)
-                       return -ret;
+                       return ret;
 
                return 0;
        }