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    Subject[PATCH 3.2 48/59] ip6_tunnel: Fix missing tunnel encapsulation limit option
    3.2.92-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Craig Gallek <cgallek@google.com>

    commit 89a23c8b528bd2c89f3981573d6cd7d23840c8a6 upstream.

    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: 333fad5364d6: ("[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>
    [bwh: Backported to 3.2: adjust context]
    Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
    ---
    net/ipv6/ip6_tunnel.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    --- a/net/ipv6/ip6_tunnel.c
    +++ b/net/ipv6/ip6_tunnel.c
    @@ -818,7 +818,7 @@ static void init_tel_txopt(struct ipv6_t
    opt->dst_opt[5] = IPV6_TLV_PADN;
    opt->dst_opt[6] = 1;

    - opt->ops.dst0opt = (struct ipv6_opt_hdr *) opt->dst_opt;
    + opt->ops.dst1opt = (struct ipv6_opt_hdr *) opt->dst_opt;
    opt->ops.opt_nflen = 8;
    }

    @@ -989,7 +989,7 @@ static int ip6_tnl_xmit2(struct sk_buff
    proto = fl6->flowi6_proto;
    if (encap_limit >= 0) {
    init_tel_txopt(&opt, encap_limit);
    - ipv6_push_nfrag_opts(skb, &opt.ops, &proto, NULL);
    + ipv6_push_frag_opts(skb, &opt.ops, &proto);
    }
    skb_push(skb, sizeof(struct ipv6hdr));
    skb_reset_network_header(skb);
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