ipv6: reassembly: use seperate reassembly queues for conntrack and local delivery

Currently the same reassembly queue might be used for packets reassembled
by conntrack in different positions in the stack (PREROUTING/LOCAL_OUT),
as well as local delivery. This can cause "packet jumps" when the fragment
completing a reassembled packet is queued from a different position in the
stack than the previous ones.

Add a "user" identifier to the reassembly queue key to seperate the queues
of each caller, similar to what we do for IPv4.

Signed-off-by: Patrick McHardy <kaber@trash.net>

include/net/ipv6.h

@@ -350,8 +350,15 @@ static inline int ipv6_prefix_equal(const struct in6_addr *a1,
 
 struct inet_frag_queue;
 
+enum ip6_defrag_users {
+	IP6_DEFRAG_LOCAL_DELIVER,
+	IP6_DEFRAG_CONNTRACK_IN,
+	IP6_DEFRAG_CONNTRACK_OUT,
+};
+
 struct ip6_create_arg {
 	__be32 id;
+	u32 user;
 	struct in6_addr *src;
 	struct in6_addr *dst;
 };