net: rtnetlink: add possibility to use alternative names as message handle

Extend the basic rtnetlink commands to use alternative interface names
as a handle instead of ifindex and ifname.
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/rtnetlink.c

@@ -2780,14 +2780,17 @@ static int do_setlink(const struct sk_buff *skb,
 
 static struct net_device *rtnl_dev_get(struct net *net,
 				       struct nlattr *ifname_attr,
+				       struct nlattr *altifname_attr,
 				       char *ifname)
 {
-	char buffer[IFNAMSIZ];
+	char buffer[ALTIFNAMSIZ];
 
 	if (!ifname) {
 		ifname = buffer;
 		if (ifname_attr)
 			nla_strlcpy(ifname, ifname_attr, IFNAMSIZ);
+		else if (altifname_attr)
+			nla_strlcpy(ifname, altifname_attr, ALTIFNAMSIZ);
 		else
 			return NULL;
 	}
@@ -2823,8 +2826,8 @@ static int rtnl_setlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 	ifm = nlmsg_data(nlh);
 	if (ifm->ifi_index > 0)
 		dev = __dev_get_by_index(net, ifm->ifi_index);
-	else if (tb[IFLA_IFNAME])
-		dev = rtnl_dev_get(net, NULL, ifname);
+	else if (tb[IFLA_IFNAME] || tb[IFLA_ALT_IFNAME])
+		dev = rtnl_dev_get(net, NULL, tb[IFLA_ALT_IFNAME], ifname);
 	else
 		goto errout;
 
@@ -2921,8 +2924,9 @@ static int rtnl_dellink(struct sk_buff *skb, struct nlmsghdr *nlh,
 	ifm = nlmsg_data(nlh);
 	if (ifm->ifi_index > 0)
 		dev = __dev_get_by_index(tgt_net, ifm->ifi_index);
-	else if (tb[IFLA_IFNAME])
-		dev = rtnl_dev_get(net, tb[IFLA_IFNAME], NULL);
+	else if (tb[IFLA_IFNAME] || tb[IFLA_ALT_IFNAME])
+		dev = rtnl_dev_get(net, tb[IFLA_IFNAME],
+				   tb[IFLA_ALT_IFNAME], NULL);
 	else if (tb[IFLA_GROUP])
 		err = rtnl_group_dellink(tgt_net, nla_get_u32(tb[IFLA_GROUP]));
 	else
@@ -3093,8 +3097,8 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 	ifm = nlmsg_data(nlh);
 	if (ifm->ifi_index > 0)
 		dev = __dev_get_by_index(net, ifm->ifi_index);
-	else if (tb[IFLA_IFNAME])
-		dev = rtnl_dev_get(net, NULL, ifname);
+	else if (tb[IFLA_IFNAME] || tb[IFLA_ALT_IFNAME])
+		dev = rtnl_dev_get(net, NULL, tb[IFLA_ALT_IFNAME], ifname);
 	else
 		dev = NULL;
 
@@ -3358,6 +3362,7 @@ static int rtnl_valid_getlink_req(struct sk_buff *skb,
 
 		switch (i) {
 		case IFLA_IFNAME:
+		case IFLA_ALT_IFNAME:
 		case IFLA_EXT_MASK:
 		case IFLA_TARGET_NETNSID:
 			break;
@@ -3405,8 +3410,9 @@ static int rtnl_getlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 	ifm = nlmsg_data(nlh);
 	if (ifm->ifi_index > 0)
 		dev = __dev_get_by_index(tgt_net, ifm->ifi_index);
-	else if (tb[IFLA_IFNAME])
-		dev = rtnl_dev_get(tgt_net, tb[IFLA_IFNAME], NULL);
+	else if (tb[IFLA_IFNAME] || tb[IFLA_ALT_IFNAME])
+		dev = rtnl_dev_get(tgt_net, tb[IFLA_IFNAME],
+				   tb[IFLA_ALT_IFNAME], NULL);
 	else
 		goto out;
 
@@ -3491,8 +3497,9 @@ static int rtnl_linkprop(int cmd, struct sk_buff *skb, struct nlmsghdr *nlh,
 	ifm = nlmsg_data(nlh);
 	if (ifm->ifi_index > 0)
 		dev = __dev_get_by_index(net, ifm->ifi_index);
-	else if (tb[IFLA_IFNAME])
-		dev = rtnl_dev_get(net, tb[IFLA_IFNAME], NULL);
+	else if (tb[IFLA_IFNAME] || tb[IFLA_ALT_IFNAME])
+		dev = rtnl_dev_get(net, tb[IFLA_IFNAME],
+				   tb[IFLA_ALT_IFNAME], NULL);
 	else
 		return -EINVAL;