In RFC 4213, section 3.4, page 11, it says:
If sufficient data bytes from the offending packet are available, the
encapsulator MAY extract the encapsulated IPv6 packet and use it to
generate an ICMPv6 message directed back to the originating IPv6 node.
Currently, linux does not do that.
More info on the RFC: http://tools.ietf.org/html/rfc4213
Issue described also in https://bugzilla.kernel.org/show_bug.cgi?id=49761
I'm considering to implement this feature.
Will be interesting to do it?
Regards,
Oussama