Merge branch 'rtnetlink-honour-nlm_f_echo-flag-in-rtnl_-new-del-link'

Hangbin Liu says:

====================
rtnetlink: Honour NLM_F_ECHO flag in rtnl_{new, del}link

Netlink messages are used for communicating between user and kernel space.
When user space configures the kernel with netlink messages, it can set the
NLM_F_ECHO flag to request the kernel to send the applied configuration back
to the caller. This allows user space to retrieve configuration information
that are filled by the kernel (either because these parameters can only be
set by the kernel or because user space let the kernel choose a default
value).

The kernel has support this feature in some places like RTM_{NEW, DEL}ADDR,
RTM_{NEW, DEL}ROUTE. This patch set handles NLM_F_ECHO flag and send link
info back after rtnl_{new, del}link.
====================

Link: https://lore.kernel.org/r/20221028084224.3509611-1-liuhangbin@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 28 insertions, 20 deletions

diff --git a/net/core/dev.c b/net/core/dev.c
index cfb68db040a4..2e4f1c97b59e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1333,7 +1333,7 @@ void netdev_state_change(struct net_device *dev)
 
 		call_netdevice_notifiers_info(NETDEV_CHANGE,
 					      &change_info.info);
-		rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_KERNEL);
+		rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_KERNEL, 0, NULL);
 	}
 }
 EXPORT_SYMBOL(netdev_state_change);
@@ -1469,7 +1469,7 @@ int dev_open(struct net_device *dev, struct netlink_ext_ack *extack)
 	if (ret < 0)
 		return ret;
 
-	rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL);
+	rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP | IFF_RUNNING, GFP_KERNEL, 0, NULL);
 	call_netdevice_notifiers(NETDEV_UP, dev);
 
 	return ret;
@@ -1541,7 +1541,7 @@ void dev_close_many(struct list_head *head, bool unlink)
 	__dev_close_many(head);
 
 	list_for_each_entry_safe(dev, tmp, head, close_list) {
-		rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL);
+		rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP | IFF_RUNNING, GFP_KERNEL, 0, NULL);
 		call_netdevice_notifiers(NETDEV_DOWN, dev);
 		if (unlink)
 			list_del_init(&dev->close_list);
@@ -8351,7 +8351,7 @@ static int __dev_set_promiscuity(struct net_device *dev, int inc, bool notify)
 		dev_change_rx_flags(dev, IFF_PROMISC);
 	}
 	if (notify)
-		__dev_notify_flags(dev, old_flags, IFF_PROMISC);
+		__dev_notify_flags(dev, old_flags, IFF_PROMISC, 0, NULL);
 	return 0;
 }
 
@@ -8406,7 +8406,7 @@ static int __dev_set_allmulti(struct net_device *dev, int inc, bool notify)
 		dev_set_rx_mode(dev);
 		if (notify)
 			__dev_notify_flags(dev, old_flags,
-					   dev->gflags ^ old_gflags);
+					   dev->gflags ^ old_gflags, 0, NULL);
 	}
 	return 0;
 }
@@ -8569,12 +8569,13 @@ int __dev_change_flags(struct net_device *dev, unsigned int flags,
 }
 
 void __dev_notify_flags(struct net_device *dev, unsigned int old_flags,
-			unsigned int gchanges)
+			unsigned int gchanges, u32 portid,
+			const struct nlmsghdr *nlh)
 {
 	unsigned int changes = dev->flags ^ old_flags;
 
 	if (gchanges)
-		rtmsg_ifinfo(RTM_NEWLINK, dev, gchanges, GFP_ATOMIC);
+		rtmsg_ifinfo(RTM_NEWLINK, dev, gchanges, GFP_ATOMIC, portid, nlh);
 
 	if (changes & IFF_UP) {
 		if (dev->flags & IFF_UP)
@@ -8616,7 +8617,7 @@ int dev_change_flags(struct net_device *dev, unsigned int flags,
 		return ret;
 
 	changes = (old_flags ^ dev->flags) | (old_gflags ^ dev->gflags);
-	__dev_notify_flags(dev, old_flags, changes);
+	__dev_notify_flags(dev, old_flags, changes, 0, NULL);
 	return ret;
 }
 EXPORT_SYMBOL(dev_change_flags);
@@ -10101,7 +10102,7 @@ int register_netdevice(struct net_device *dev)
 	 */
 	if (!dev->rtnl_link_ops ||
 	    dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
-		rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL);
+		rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL, 0, NULL);
 
 out:
 	return ret;
@@ -10780,14 +10781,8 @@ void unregister_netdevice_queue(struct net_device *dev, struct list_head *head)
 }
 EXPORT_SYMBOL(unregister_netdevice_queue);
 
-/**
- *	unregister_netdevice_many - unregister many devices
- *	@head: list of devices
- *
- *  Note: As most callers use a stack allocated list_head,
- *  we force a list_del() to make sure stack wont be corrupted later.
- */
-void unregister_netdevice_many(struct list_head *head)
+void unregister_netdevice_many_notify(struct list_head *head,
+				      u32 portid, const struct nlmsghdr *nlh)
 {
 	struct net_device *dev, *tmp;
 	LIST_HEAD(close_head);
@@ -10849,7 +10844,8 @@ void unregister_netdevice_many(struct list_head *head)
 		if (!dev->rtnl_link_ops ||
 		    dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
 			skb = rtmsg_ifinfo_build_skb(RTM_DELLINK, dev, ~0U, 0,
-						     GFP_KERNEL, NULL, 0);
+						     GFP_KERNEL, NULL, 0,
+						     portid, nlmsg_seq(nlh));
 
 		/*
 		 *	Flush the unicast and multicast chains
@@ -10864,7 +10860,7 @@ void unregister_netdevice_many(struct list_head *head)
 			dev->netdev_ops->ndo_uninit(dev);
 
 		if (skb)
-			rtmsg_ifinfo_send(skb, dev, GFP_KERNEL);
+			rtmsg_ifinfo_send(skb, dev, GFP_KERNEL, portid, nlh);
 
 		/* Notifier chain MUST detach us all upper devices. */
 		WARN_ON(netdev_has_any_upper_dev(dev));
@@ -10887,6 +10883,18 @@ void unregister_netdevice_many(struct list_head *head)
 
 	list_del(head);
 }
+
+/**
+ *	unregister_netdevice_many - unregister many devices
+ *	@head: list of devices
+ *
+ *  Note: As most callers use a stack allocated list_head,
+ *  we force a list_del() to make sure stack wont be corrupted later.
+ */
+void unregister_netdevice_many(struct list_head *head)
+{
+	unregister_netdevice_many_notify(head, 0, NULL);
+}
 EXPORT_SYMBOL(unregister_netdevice_many);
 
 /**
@@ -11042,7 +11050,7 @@ int __dev_change_net_namespace(struct net_device *dev, struct net *net,
 	 *	Prevent userspace races by waiting until the network
 	 *	device is fully setup before sending notifications.
 	 */
-	rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL);
+	rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL, 0, NULL);
 
 	synchronize_net();
 	err = 0;