[PATCH v2 net-next 3/7] nexthop: Move NHA_OIF validation to rtm_to_nh_config_rtnl().

[Kuniyuki Iwashima <kuniyu@amazon.com>]

NHA_OIF needs to look up a device by __dev_get_by_index(),
which requires RTNL.

Let's move NHA_OIF validation to rtm_to_nh_config_rtnl().

Note that the proceeding checks made the original !cfg->nh_fdb
check redundant.

  NHA_FDB is set           -> NHA_OIF cannot be set
  NHA_FDB is set but false -> NHA_OIF must be set
  NHA_FDB is not set       -> NHA_OIF must be set

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/ipv4/nexthop.c | 43 +++++++++++++++++++++++--------------------
 1 file changed, 23 insertions(+), 20 deletions(-)

diff --git a/net/ipv4/nexthop.c b/net/ipv4/nexthop.c
index d30edc14b039..426cdf301c6f 100644
--- a/net/ipv4/nexthop.c
+++ b/net/ipv4/nexthop.c
@@ -3134,25 +3134,6 @@ static int rtm_to_nh_config(struct net *net, struct sk_buff *skb,
 		goto out;
 	}
 
-	if (!cfg->nh_fdb && tb[NHA_OIF]) {
-		cfg->nh_ifindex = nla_get_u32(tb[NHA_OIF]);
-		if (cfg->nh_ifindex)
-			cfg->dev = __dev_get_by_index(net, cfg->nh_ifindex);
-
-		if (!cfg->dev) {
-			NL_SET_ERR_MSG(extack, "Invalid device index");
-			goto out;
-		} else if (!(cfg->dev->flags & IFF_UP)) {
-			NL_SET_ERR_MSG(extack, "Nexthop device is not up");
-			err = -ENETDOWN;
-			goto out;
-		} else if (!netif_carrier_ok(cfg->dev)) {
-			NL_SET_ERR_MSG(extack, "Carrier for nexthop device is down");
-			err = -ENETDOWN;
-			goto out;
-		}
-	}
-
 	err = -EINVAL;
 	if (tb[NHA_GATEWAY]) {
 		struct nlattr *gwa = tb[NHA_GATEWAY];
@@ -3216,11 +3197,33 @@ static int rtm_to_nh_config(struct net *net, struct sk_buff *skb,
 }
 
 static int rtm_to_nh_config_rtnl(struct net *net, struct nlattr **tb,
+				 struct nh_config *cfg,
 				 struct netlink_ext_ack *extack)
 {
 	if (tb[NHA_GROUP])
 		return nh_check_attr_group_rtnl(net, tb, extack);
 
+	if (tb[NHA_OIF]) {
+		cfg->nh_ifindex = nla_get_u32(tb[NHA_OIF]);
+		if (cfg->nh_ifindex)
+			cfg->dev = __dev_get_by_index(net, cfg->nh_ifindex);
+
+		if (!cfg->dev) {
+			NL_SET_ERR_MSG(extack, "Invalid device index");
+			return -EINVAL;
+		}
+
+		if (!(cfg->dev->flags & IFF_UP)) {
+			NL_SET_ERR_MSG(extack, "Nexthop device is not up");
+			return -ENETDOWN;
+		}
+
+		if (!netif_carrier_ok(cfg->dev)) {
+			NL_SET_ERR_MSG(extack, "Carrier for nexthop device is down");
+			return -ENETDOWN;
+		}
+	}
+
 	return 0;
 }
 
@@ -3244,7 +3247,7 @@ static int rtm_new_nexthop(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (err)
 		goto out;
 
-	err = rtm_to_nh_config_rtnl(net, tb, extack);
+	err = rtm_to_nh_config_rtnl(net, tb, &cfg, extack);
 	if (err)
 		goto out;
 
-- 
2.48.1