udp6: fix UDP/IPv6 encap resubmit path

commit 59dca1d8a6725a121dae6c452de0b2611d5865dc upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 62ab2047218a5ebd6191b88f1be072d79acb7370..f4989e72568e861ff7cfc9faaaf2c2a866c73ac2 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -842,11 +842,9 @@ int __udp6_lib_rcv(struct sk_buff *skb, struct udp_table *udptable,
                int 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;
        }