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udp6: fix UDP/IPv6 encap resubmit path

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[ Upstream commit 59dca1d8a6725a121dae6c452de0b2611d5865dc ]

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>
This commit is contained in:
Bill Sommerfeld 2016-03-04 14:47:21 -08:00 committed by Greg Kroah-Hartman
parent 2d11623bd0
commit 8a2226c17e
1 changed files with 2 additions and 4 deletions
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6
net/ipv6/udp.c
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@ -916,11 +916,9 @@ 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;
}