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    Subject[PATCH 3.18 16/68] net: ipv4: fix multipath RTM_GETROUTE behavior when iif is given
    Date
    3.18-stable review patch.  If anyone has any objections, please let me know.

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

    From: Florian Larysch <fl@n621.de>


    [ Upstream commit a8801799c6975601fd58ae62f48964caec2eb83f ]

    inet_rtm_getroute synthesizes a skeletal ICMP skb, which is passed to
    ip_route_input when iif is given. If a multipath route is present for
    the designated destination, ip_multipath_icmp_hash ends up being called,
    which uses the source/destination addresses within the skb to calculate
    a hash. However, those are not set in the synthetic skb, causing it to
    return an arbitrary and incorrect result.

    Instead, use UDP, which gets no such special treatment.

    Signed-off-by: Florian Larysch <fl@n621.de>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    net/ipv4/route.c | 2 +-
    1 file changed, 1 insertion(+), 1 deletion(-)

    --- a/net/ipv4/route.c
    +++ b/net/ipv4/route.c
    @@ -2436,7 +2436,7 @@ static int inet_rtm_getroute(struct sk_b
    skb_reset_network_header(skb);

    /* Bugfix: need to give ip_route_input enough of an IP header to not gag. */
    - ip_hdr(skb)->protocol = IPPROTO_ICMP;
    + ip_hdr(skb)->protocol = IPPROTO_UDP;
    skb_reserve(skb, MAX_HEADER + sizeof(struct iphdr));

    src = tb[RTA_SRC] ? nla_get_be32(tb[RTA_SRC]) : 0;

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