• Hannes Frederic Sowa's avatar
    ipv6: add anti-spoofing checks for 6to4 and 6rd · 218774dc
    Hannes Frederic Sowa authored
    This patch adds anti-spoofing checks in sit.c as specified in RFC3964
    section 5.2 for 6to4 and RFC5969 section 12 for 6rd. I left out the
    checks which could easily be implemented with netfilter.
    
    Specifically this patch adds following logic (based loosely on the
    pseudocode in RFC3964 section 5.2):
    
    if prefix (inner_src_v6) == rd6_prefix (2002::/16 is the default)
            and outer_src_v4 != embedded_ipv4 (inner_src_v6)
                    drop
    if prefix (inner_dst_v6) == rd6_prefix (or 2002::/16 is the default)
            and outer_dst_v4 != embedded_ipv4 (inner_dst_v6)
                    drop
    accept
    
    To accomplish the specified security checks proposed by above RFCs,
    it is still necessary to employ uRPF filters with netfilter. These new
    checks only kick in if the employed addresses are within the 2002::/16 or
    another range specified by the 6rd-prefix (which defaults to 2002::/16).
    
    Cc: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
    Cc: David Miller <davem@davemloft.net>
    Signed-off-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    218774dc
sit.c 37.1 KB