On 1/7/21 7:48 AM, Ido Schimmel wrote:
> From: Petr Machata <pe...@nvidia.com>
>
> The function nh_check_attr_group() is called to validate nexthop groups.
> The intention of that code seems to have been to bounce all attributes
> above NHA_GROUP_TYPE except for NHA_FDB. However instead it bounces all
> these attributes except when NHA_FDB attribute is present--then it accepts
> them.
>
> NHA_FDB validation that takes place before, in rtm_to_nh_config(), already
> bounces NHA_OIF, NHA_BLACKHOLE, NHA_ENCAP and NHA_ENCAP_TYPE. Yet further
> back, NHA_GROUPS and NHA_MASTER are bounced unconditionally.
>
> But that still leaves NHA_GATEWAY as an attribute that would be accepted in
> FDB nexthop groups (with no meaning), so long as it keeps the address
> family as unspecified:
>
> # ip nexthop add id 1 fdb via 127.0.0.1
> # ip nexthop add id 10 fdb via default group 1
>
> The nexthop code is still relatively new and likely not used very broadly,
> and the FDB bits are newer still. Even though there is a reproducer out
> there, it relies on an improbable gateway arguments "via default", "via
> all" or "via any". Given all this, I believe it is OK to reformulate the
> condition to do the right thing and bounce NHA_GATEWAY.
>
> Fixes: 38428d68719c ("nexthop: support for fdb ecmp nexthops")
> Signed-off-by: Petr Machata <pe...@nvidia.com>
> Signed-off-by: Ido Schimmel <ido...@nvidia.com>
> ---
> net/ipv4/nexthop.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
Reviewed-by: David Ahern <dsah...@kernel.org>
