rtnetlink: Call validate_linkmsg() in do_setlink().

There are 3 paths that finally call do_setlink(), and validate_linkmsg()
is called in each path.

  1. RTM_NEWLINK
    1-1. dev is found in __rtnl_newlink()
    1-2. dev isn't found, but IFLA_GROUP is specified in
          rtnl_group_changelink()
  2. RTM_SETLINK

The next patch factorises 1-1 to a separate function.

As a preparation, let's move validate_linkmsg() calls to do_setlink().

Signed-off-by: Kuniyuki Iwashima <[email protected]>
Reviewed-by: Eric Dumazet <[email protected]>
Signed-off-by: Paolo Abeni <[email protected]>

Author: q2ven

net/core/rtnetlink.c

@@ -2855,6 +2855,10 @@ static int do_setlink(const struct sk_buff *skb,
 	char ifname[IFNAMSIZ];
 	int err;
 
+	err = validate_linkmsg(dev, tb, extack);
+	if (err < 0)
+		goto errout;
+
 	if (tb[IFLA_IFNAME])
 		nla_strscpy(ifname, tb[IFLA_IFNAME], IFNAMSIZ);
 	else
@@ -3269,10 +3273,6 @@ static int rtnl_setlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 		goto errout;
 	}
 
-	err = validate_linkmsg(dev, tb, extack);
-	if (err < 0)
-		goto errout;
-
 	err = do_setlink(skb, dev, ifm, extack, tb, 0);
 errout:
 	return err;
@@ -3516,9 +3516,6 @@ static int rtnl_group_changelink(const struct sk_buff *skb,
 
 	for_each_netdev_safe(net, dev, aux) {
 		if (dev->group == group) {
-			err = validate_linkmsg(dev, tb, extack);
-			if (err < 0)
-				return err;
 			err = do_setlink(skb, dev, ifm, extack, tb, 0);
 			if (err < 0)
 				return err;
@@ -3744,10 +3741,6 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 		if (nlh->nlmsg_flags & NLM_F_REPLACE)
 			return -EOPNOTSUPP;
 
-		err = validate_linkmsg(dev, tb, extack);
-		if (err < 0)
-			return err;
-
 		if (linkinfo[IFLA_INFO_DATA]) {
 			if (!ops || ops != dev->rtnl_link_ops ||
 			    !ops->changelink)