From b19218b27f3477316d296e8bcf4446aaf017aa69 Mon Sep 17 00:00:00 2001 From: Petr Machata Date: Thu, 7 Jan 2021 16:48:23 +0200 Subject: [PATCH] nexthop: Bounce NHA_GATEWAY in FDB nexthop groups 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 Signed-off-by: Ido Schimmel Reviewed-by: David Ahern Signed-off-by: Jakub Kicinski --- net/ipv4/nexthop.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c index 712cdc061cde..e53e43aef785 100644 --- a/net/ipv4/nexthop.c +++ b/net/ipv4/nexthop.c @@ -627,7 +627,7 @@ static int nh_check_attr_group(struct net *net, struct nlattr *tb[], for (i = NHA_GROUP_TYPE + 1; i < __NHA_MAX; ++i) { if (!tb[i]) continue; - if (tb[NHA_FDB]) + if (i == NHA_FDB) continue; NL_SET_ERR_MSG(extack, "No other attributes can be set in nexthop groups");