The IPv6 tunneling code tries to insert IPV6_TLV_TNL_ENCAP_LIMIT and
IPV6_TLV_PADN options when an encapsulation limit is defined (the
default is a limit of 4). An MTU adjustment is done to account for
these options as well. However, the options are never present in the
generated packets.
The issue appears to be a subtlety between IPV6_DSTOPTS and
IPV6_RTHDRDSTOPTS defined in RFC 3542. When the IPIP tunnel driver was
written, the encap limit options were included as IPV6_RTHDRDSTOPTS in
dst0opt of struct ipv6_txoptions. Later, ipv6_push_nfrags_opts was
(correctly) updated to require IPV6_RTHDR options when IPV6_RTHDRDSTOPTS
are to be used. This caused the options to no longer be included in v6
encapsulated packets.
The fix is to use IPV6_DSTOPTS (in dst1opt of struct ipv6_txoptions)
instead. IPV6_DSTOPTS do not have the additional IPV6_RTHDR requirement.
Fixes: 1df64a8569c7: ("[IPV6]: Add ip6ip6 tunnel driver.")
Fixes: 333fad5364: ("[IPV6]: Support several new sockopt / ancillary data in Advanced API (RFC3542)")
Signed-off-by: Craig Gallek <kraig@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
89a23c8b52