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

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Date: Wed, 30 Aug 2023 14:16:22 +0800
From: Hangbin Liu <liuhangbin@...il.com>
To: netdev@...r.kernel.org
Cc: "David S . Miller" <davem@...emloft.net>,
	David Ahern <dsahern@...nel.org>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Ido Schimmel <idosch@...sch.org>,
	Hangbin Liu <liuhangbin@...il.com>,
	Thomas Haller <thaller@...hat.com>
Subject: [PATCH net-next] ipv6: do not merge differe type and protocol routes

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
---
 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
-- 
2.41.0