On 11/21/17 12:50 AM, Ido Schimmel wrote:
> When the 'ignore_routes_with_linkdown' sysctl is set, we should not
> consider linkdown nexthops during route lookup.
>
> While the code correctly verifies that the initially selected route
> ('match') has a carrier, it does not perform the same check in the
> subsequent multipath selection, resulting in a potential packet loss.
>
> In case the chosen route does not have a carrier and the sysctl is set,
> choose the initially selected route.
>
> Fixes: 35103d11173b ("net: ipv6 sysctl option to ignore routes when nexthop
> link is down")
> Signed-off-by: Ido Schimmel <[email protected]>
> ---
> net/ipv6/route.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 05eb7bc36156..0363db914c7a 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -472,6 +472,11 @@ static struct rt6_info *rt6_multipath_select(struct
> rt6_info *match,
> &match->rt6i_siblings, rt6i_siblings) {
> route_choosen--;
> if (route_choosen == 0) {
> + struct inet6_dev *idev = sibling->rt6i_idev;
> +
> + if (!netif_carrier_ok(sibling->dst.dev) &&
> + idev->cnf.ignore_routes_with_linkdown)
> + break;
> if (rt6_score_route(sibling, oif, strict) < 0)
> break;
> match = sibling;
>
Looks right to me.
Acked-by: David Ahern <[email protected]>
