rp_filter disabled (all = 0) and still get "martians"

I've been trying to some IPsec with Click, and I thought
tunneling would be trivial: just enable forwarding
and disable rp_filters -- no such luck! I've

eth1: 192.168.0.14/24
tun0: 10.0.0.1/8

What tun0 basicly tries to do, is to add

dst 10.0.0.2 -> tun0 -> ...
   ... User space adds tunnel
   ...   dst=192.168.0.15
   ...   src=192.168.0.14
   ... and returns packet to tun0
-> tun0 -> expect it to be routed to eth1

But, I still get it dropped as martian, maybe
due to src address? (Routes fine if src is not
192.168.0.14, like 192.168.1.14).

[ 2801.224711] martian source 192.168.0.15 from 192.168.0.14, on dev tun0

Is there any way to disable this "feature"?

And, even better, it would be wonderful, if
specifying src=0.0.0.0 would automatically
fill in the correct source depending on the
final interface.

I'm doing this on

2.6.38-14-generic #58-Ubuntu SMP Tue Mar 27 18:48:46 UTC 2012 i686 i686 
i386 GNU/Linux