net: add extack arg for link ops

Pass extack arg to validate_linkmsg and validate_link_af callbacks.
If a netlink attribute has a reject_message, use the extended ack
mechanism to carry the message back to user space.

Signed-off-by: Rocco Yue <[email protected]>
Reviewed-by: David Ahern <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Rocco Yue

include/net/rtnetlink.h

@@ -153,7 +153,8 @@ struct rtnl_af_ops {
 						    u32 ext_filter_mask);
 
 	int			(*validate_link_af)(const struct net_device *dev,
-						    const struct nlattr *attr);
+						    const struct nlattr *attr,
+						    struct netlink_ext_ack *extack);
 	int			(*set_link_af)(struct net_device *dev,
 					       const struct nlattr *attr,
 					       struct netlink_ext_ack *extack);

net/core/rtnetlink.c

@@ -2257,7 +2257,8 @@ static int rtnl_ensure_unique_netns(struct nlattr *tb[],
 	return -EINVAL;
 }
 
-static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[])
+static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[],
+			    struct netlink_ext_ack *extack)
 {
 	if (dev) {
 		if (tb[IFLA_ADDRESS] &&
@@ -2284,7 +2285,7 @@ static int validate_linkmsg(struct net_device *dev, struct nlattr *tb[])
 				return -EOPNOTSUPP;
 
 			if (af_ops->validate_link_af) {
-				err = af_ops->validate_link_af(dev, af);
+				err = af_ops->validate_link_af(dev, af, extack);
 				if (err < 0)
 					return err;
 			}
@@ -2592,7 +2593,7 @@ static int do_setlink(const struct sk_buff *skb,
 	const struct net_device_ops *ops = dev->netdev_ops;
 	int err;
 
-	err = validate_linkmsg(dev, tb);
+	err = validate_linkmsg(dev, tb, extack);
 	if (err < 0)
 		return err;
 
@@ -3290,7 +3291,7 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 			m_ops = master_dev->rtnl_link_ops;
 	}
 
-	err = validate_linkmsg(dev, tb);
+	err = validate_linkmsg(dev, tb, extack);
 	if (err < 0)
 		return err;
 

net/ipv4/devinet.c

@@ -1950,7 +1950,8 @@ static const struct nla_policy inet_af_policy[IFLA_INET_MAX+1] = {
 };
 
 static int inet_validate_link_af(const struct net_device *dev,
-				 const struct nlattr *nla)
+				 const struct nlattr *nla,
+				 struct netlink_ext_ack *extack)
 {
 	struct nlattr *a, *tb[IFLA_INET_MAX+1];
 	int err, rem;
@@ -1959,7 +1960,7 @@ static int inet_validate_link_af(const struct net_device *dev,
 		return -EAFNOSUPPORT;
 
 	err = nla_parse_nested_deprecated(tb, IFLA_INET_MAX, nla,
-					  inet_af_policy, NULL);
+					  inet_af_policy, extack);
 	if (err < 0)
 		return err;
 

net/ipv6/addrconf.c

@@ -5792,7 +5792,8 @@ static int check_stable_privacy(struct inet6_dev *idev, struct net *net,
 }
 
 static int inet6_validate_link_af(const struct net_device *dev,
-				  const struct nlattr *nla)
+				  const struct nlattr *nla,
+				  struct netlink_ext_ack *extack)
 {
 	struct nlattr *tb[IFLA_INET6_MAX + 1];
 	struct inet6_dev *idev = NULL;
@@ -5805,7 +5806,7 @@ static int inet6_validate_link_af(const struct net_device *dev,
 	}
 
 	err = nla_parse_nested_deprecated(tb, IFLA_INET6_MAX, nla,
-					  inet6_af_policy, NULL);
+					  inet6_af_policy, extack);
 	if (err)
 		return err;