netdev - Re: [PATCH net-next] ipv6: do not merge differe type and protocol routes

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Message-ID: <06c4cd5f-7241-3a72-0cab-5319b2c8a793@kernel.org>
Date: Wed, 30 Aug 2023 08:49:18 -0600
From: David Ahern <dsahern@...nel.org>
To: Hangbin Liu <liuhangbin@...il.com>, netdev@...r.kernel.org
Cc: "David S . Miller" <davem@...emloft.net>,
 Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>,
 Paolo Abeni <pabeni@...hat.com>, Ido Schimmel <idosch@...sch.org>,
 Thomas Haller <thaller@...hat.com>
Subject: Re: [PATCH net-next] ipv6: do not merge differe type and protocol
 routes

On 8/30/23 12:15 AM, Hangbin Liu wrote:
> Different with IPv4, IPv6 will auto merge the same metric routes into
> multipath routes. But the different type and protocol routes are also
> merged, which will lost user's configure info. e.g.
> 
> + ip route add local 2001:db8:103::/64 via 2001:db8:101::10 dev dummy1 table 100
> + ip route append unicast 2001:db8:103::/64 via 2001:db8:101::10 dev dummy2 table 100
> + ip -6 route show table 100
> local 2001:db8:103::/64 metric 1024 pref medium
>         nexthop via 2001:db8:101::10 dev dummy1 weight 1
>         nexthop via 2001:db8:101::10 dev dummy2 weight 1
> 
> + ip route add 2001:db8:104::/64 via 2001:db8:101::10 dev dummy1 proto kernel table 200
> + ip route append 2001:db8:104::/64 via 2001:db8:101::10 dev dummy2 proto bgp table 200
> + ip -6 route show table 200
> 2001:db8:104::/64 proto kernel metric 1024 pref medium
>         nexthop via 2001:db8:101::10 dev dummy1 weight 1
>         nexthop via 2001:db8:101::10 dev dummy2 weight 1
> 
> So let's skip counting the different type and protocol routes as siblings.
> After update, the different type/protocol routes will not be merged.
> 
> + ip -6 route show table 100
> local 2001:db8:103::/64 via 2001:db8:101::10 dev dummy1 metric 1024 pref medium
> 2001:db8:103::/64 via 2001:db8:101::10 dev dummy2 metric 1024 pref medium
> 
> + ip -6 route show table 200
> 2001:db8:104::/64 via 2001:db8:101::10 dev dummy1 proto kernel metric 1024 pref medium
> 2001:db8:104::/64 via 2001:db8:101::10 dev dummy2 proto bgp metric 1024 pref medium
> 
> Reported-by: Thomas Haller <thaller@...hat.com>
> Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2161994
> Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
> ---
> All fib test passed:
> Tests passed: 203
> Tests failed:   0

Please add the above tests for this case to the fib tests script.

> ---
>  net/ipv6/ip6_fib.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
> index 28b01a068412..f60f5d14f034 100644
> --- a/net/ipv6/ip6_fib.c
> +++ b/net/ipv6/ip6_fib.c
> @@ -1133,6 +1133,11 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
>  							rt->fib6_pmtu);
>  				return -EEXIST;
>  			}
> +
> +			if (iter->fib6_type != rt->fib6_type ||
> +			    iter->fib6_protocol != rt->fib6_protocol)
> +				goto next_iter;
> +
>  			/* If we have the same destination and the same metric,
>  			 * but not the same gateway, then the route we try to
>  			 * add is sibling to this route, increment our counter

Reviewed-by: David Ahern <dsahern@...nel.org>