[PATCH v2 net-next 09/14] rtnetlink: Fetch IFLA_LINK_NETNSID in rtnl_newlink().

[Kuniyuki Iwashima <kuniyu@amazon.com>]

Another netns option for RTM_NEWLINK is IFLA_LINK_NETNSID and
is fetched in rtnl_newlink_create().

This must be done before holding rtnl_net_lock().

Let's move IFLA_LINK_NETNSID processing to rtnl_newlink().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
---
 net/core/rtnetlink.c | 49 ++++++++++++++++++++++----------------------
 1 file changed, 24 insertions(+), 25 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index f6823c8d21ad..eee0f820ddf6 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3634,7 +3634,7 @@ static int rtnl_group_changelink(const struct sk_buff *skb,
 
 static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
 			       const struct rtnl_link_ops *ops,
-			       struct net *tgt_net,
+			       struct net *tgt_net, struct net *link_net,
 			       const struct nlmsghdr *nlh,
 			       struct nlattr **tb, struct nlattr **data,
 			       struct netlink_ext_ack *extack)
@@ -3644,7 +3644,6 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
 	u32 portid = NETLINK_CB(skb).portid;
 	struct net_device *dev;
 	char ifname[IFNAMSIZ];
-	struct net *link_net;
 	int err;
 
 	if (!ops->alloc && !ops->setup)
@@ -3657,22 +3656,6 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
 		name_assign_type = NET_NAME_ENUM;
 	}
 
-	if (tb[IFLA_LINK_NETNSID]) {
-		int id = nla_get_s32(tb[IFLA_LINK_NETNSID]);
-
-		link_net = get_net_ns_by_id(tgt_net, id);
-		if (!link_net) {
-			NL_SET_ERR_MSG(extack, "Unknown network namespace id");
-			err =  -EINVAL;
-			goto out;
-		}
-		err = -EPERM;
-		if (!netlink_ns_capable(skb, link_net->user_ns, CAP_NET_ADMIN))
-			goto out;
-	} else {
-		link_net = NULL;
-	}
-
 	dev = rtnl_create_link(link_net ? : tgt_net, ifname,
 			       name_assign_type, ops, tb, extack);
 	if (IS_ERR(dev)) {
@@ -3705,9 +3688,6 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
 			goto out_unregister;
 	}
 out:
-	if (link_net)
-		put_net(link_net);
-
 	return err;
 out_unregister:
 	if (ops->newlink) {
@@ -3723,7 +3703,7 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
 
 static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 			  const struct rtnl_link_ops *ops,
-			  struct net *tgt_net,
+			  struct net *tgt_net, struct net *link_net,
 			  struct rtnl_newlink_tbs *tbs,
 			  struct nlattr **data,
 			  struct netlink_ext_ack *extack)
@@ -3772,16 +3752,16 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 		return -EOPNOTSUPP;
 	}
 
-	return rtnl_newlink_create(skb, ifm, ops, tgt_net, nlh, tb, data, extack);
+	return rtnl_newlink_create(skb, ifm, ops, tgt_net, link_net, nlh, tb, data, extack);
 }
 
 static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 			struct netlink_ext_ack *extack)
 {
 	struct nlattr **tb, **linkinfo, **data = NULL;
+	struct net *tgt_net, *link_net = NULL;
 	struct rtnl_link_ops *ops = NULL;
 	struct rtnl_newlink_tbs *tbs;
-	struct net *tgt_net;
 	int ops_srcu_index;
 	int ret;
 
@@ -3852,8 +3832,27 @@ static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 		goto put_ops;
 	}
 
-	ret = __rtnl_newlink(skb, nlh, ops, tgt_net, tbs, data, extack);
+	if (tb[IFLA_LINK_NETNSID]) {
+		int id = nla_get_s32(tb[IFLA_LINK_NETNSID]);
+
+		link_net = get_net_ns_by_id(tgt_net, id);
+		if (!link_net) {
+			NL_SET_ERR_MSG(extack, "Unknown network namespace id");
+			ret =  -EINVAL;
+			goto put_net;
+		}
+
+		if (!netlink_ns_capable(skb, link_net->user_ns, CAP_NET_ADMIN)) {
+			ret = -EPERM;
+			goto put_net;
+		}
+	}
+
+	ret = __rtnl_newlink(skb, nlh, ops, tgt_net, link_net, tbs, data, extack);
 
+put_net:
+	if (link_net)
+		put_net(link_net);
 	put_net(tgt_net);
 put_ops:
 	if (ops)
-- 
2.39.5 (Apple Git-154)