[PATCHv7 net-next 0/4] rtnetlink: Honour NLM_F_ECHO flag in rtnl_{new, del}link

[PATCHv7 net-next 0/4] rtnetlink: Honour NLM_F_ECHO flag in rtnl_{new, del}link

[Hangbin Liu]

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.

v7:
1) Fix unregister_netdevice_many() prototype warnning in patch 02

v6:
1) Rename pid to portid, make all nlh const
2) Re-order the portid, nlh parameter for each function
3) Do not add rtnl_configure_link_notify() warpper as Guillaume suggested.
   Just modify rtnl_configure_link() directly in patch 01. Also remove
   the rtmsg_ifinfo_nlh() wrapper.
4) Un-export unregister_netdevice_many_notify() in patch 02

v5:
1) Make rtnl_configure_link_notify static, reported by kernel test robot

v4:
1) Add rtnl_configure_link_notify() helper so rtnl_newlink_create could
   use it instead of creating new notify function.
2) Add unregister_netdevice_many_notify() helper so rtnl_delete_link()
   could use it instead of creating new notify function
3) Split the previous patch to 4 small patches for easier reviewing.

v3:
1) Fix group parameter in rtnl_notify.
2) Use helper rtmsg_ifinfo_build_skb() instead re-write a new one.

v2:
1) Rename rtnl_echo_link_info() to rtnl_link_notify().
2) Remove IFLA_LINK_NETNSID and IFLA_EXT_MASK, which do not fit here.
3) Add NLM_F_ECHO in rtnl_dellink. But we can't re-use the rtnl_link_notify()
   helper as we need to get the link info before rtnl_delete_link().

Hangbin Liu (4):
  rtnetlink: pass netlink message header and portid to
    rtnl_configure_link()
  net: add new helper unregister_netdevice_many_notify
  rtnetlink: Honour NLM_F_ECHO flag in rtnl_newlink_create
  rtnetlink: Honour NLM_F_ECHO flag in rtnl_delete_link

 drivers/net/can/vxcan.c        |  2 +-
 drivers/net/geneve.c           |  2 +-
 drivers/net/veth.c             |  2 +-
 drivers/net/vxlan/vxlan_core.c |  4 +--
 drivers/net/wwan/wwan_core.c   |  2 +-
 include/linux/netdevice.h      |  2 --
 include/linux/rtnetlink.h      |  9 ++++---
 include/net/netlink.h          | 11 ++++++++
 include/net/rtnetlink.h        |  5 ++--
 net/core/dev.c                 | 48 ++++++++++++++++++++--------------
 net/core/dev.h                 |  7 +++++
 net/core/rtnetlink.c           | 46 ++++++++++++++++++--------------
 net/ipv4/ip_gre.c              |  2 +-
 net/openvswitch/vport-geneve.c |  2 +-
 net/openvswitch/vport-gre.c    |  2 +-
 net/openvswitch/vport-netdev.c |  2 +-
 net/openvswitch/vport-vxlan.c  |  2 +-
 17 files changed, 91 insertions(+), 59 deletions(-)

-- 
2.37.3

[PATCHv7 net-next 1/4] rtnetlink: pass netlink message header and portid to rtnl_configure_link()

[Hangbin Liu]

This patch pass netlink message header and portid to rtnl_configure_link()
All the functions in this call chain need to add the parameters so we can
use them in the last call rtnl_notify(), and notify the userspace about
the new link info if NLM_F_ECHO flag is set.

- rtnl_configure_link()
  - __dev_notify_flags()
    - rtmsg_ifinfo()
      - rtmsg_ifinfo_event()
        - rtmsg_ifinfo_build_skb()
        - rtmsg_ifinfo_send()
	  - rtnl_notify()

Also move __dev_notify_flags() declaration to net/core/dev.h, as Jakub
suggested.

Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 drivers/net/can/vxcan.c        |  2 +-
 drivers/net/geneve.c           |  2 +-
 drivers/net/veth.c             |  2 +-
 drivers/net/vxlan/vxlan_core.c |  4 ++--
 drivers/net/wwan/wwan_core.c   |  2 +-
 include/linux/netdevice.h      |  2 --
 include/linux/rtnetlink.h      |  9 +++++----
 include/net/netlink.h          | 11 +++++++++++
 include/net/rtnetlink.h        |  3 ++-
 net/core/dev.c                 | 25 ++++++++++++------------
 net/core/dev.h                 |  4 ++++
 net/core/rtnetlink.c           | 35 ++++++++++++++++++----------------
 net/ipv4/ip_gre.c              |  2 +-
 13 files changed, 61 insertions(+), 42 deletions(-)

diff --git a/drivers/net/can/vxcan.c b/drivers/net/can/vxcan.c
index 26a472d2ea58..4068d962203d 100644
--- a/drivers/net/can/vxcan.c
+++ b/drivers/net/can/vxcan.c
@@ -236,7 +236,7 @@ static int vxcan_newlink(struct net *net, struct net_device *dev,
 
 	netif_carrier_off(peer);
 
-	err = rtnl_configure_link(peer, ifmp);
+	err = rtnl_configure_link(peer, ifmp, 0, NULL);
 	if (err < 0)
 		goto unregister_network_device;
 
diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index f393e454f45c..89ff7f8e8c7e 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -1907,7 +1907,7 @@ struct net_device *geneve_dev_create_fb(struct net *net, const char *name,
 	if (err)
 		goto err;
 
-	err = rtnl_configure_link(dev, NULL);
+	err = rtnl_configure_link(dev, NULL, 0, NULL);
 	if (err < 0)
 		goto err;
 
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 09682ea3354e..1cc92225b2f0 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -1773,7 +1773,7 @@ static int veth_newlink(struct net *src_net, struct net_device *dev,
 	veth_disable_gro(peer);
 	netif_carrier_off(peer);
 
-	err = rtnl_configure_link(peer, ifmp);
+	err = rtnl_configure_link(peer, ifmp, 0, NULL);
 	if (err < 0)
 		goto err_configure_peer;
 
diff --git a/drivers/net/vxlan/vxlan_core.c b/drivers/net/vxlan/vxlan_core.c
index 6ab669dcd1c6..92224b36787a 100644
--- a/drivers/net/vxlan/vxlan_core.c
+++ b/drivers/net/vxlan/vxlan_core.c
@@ -3794,7 +3794,7 @@ static int __vxlan_dev_create(struct net *net, struct net_device *dev,
 			goto errout;
 	}
 
-	err = rtnl_configure_link(dev, NULL);
+	err = rtnl_configure_link(dev, NULL, 0, NULL);
 	if (err < 0)
 		goto unlink;
 
@@ -4416,7 +4416,7 @@ struct net_device *vxlan_dev_create(struct net *net, const char *name,
 		return ERR_PTR(err);
 	}
 
-	err = rtnl_configure_link(dev, NULL);
+	err = rtnl_configure_link(dev, NULL, 0, NULL);
 	if (err < 0) {
 		LIST_HEAD(list_kill);
 
diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index 62e9f7d6c9fe..d72ee18476d1 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -1058,7 +1058,7 @@ static void wwan_create_default_link(struct wwan_device *wwandev,
 		goto unlock;
 	}
 
-	rtnl_configure_link(dev, NULL); /* Link initialized, notify new link */
+	rtnl_configure_link(dev, NULL, 0, NULL); /* Link initialized, notify new link */
 
 unlock:
 	rtnl_unlock();
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index eddf8ee270e7..b727ed06e582 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3855,8 +3855,6 @@ int __dev_change_flags(struct net_device *dev, unsigned int flags,
 		       struct netlink_ext_ack *extack);
 int dev_change_flags(struct net_device *dev, unsigned int flags,
 		     struct netlink_ext_ack *extack);
-void __dev_notify_flags(struct net_device *, unsigned int old_flags,
-			unsigned int gchanges);
 int dev_set_alias(struct net_device *, const char *, size_t);
 int dev_get_alias(const struct net_device *, char *, size_t);
 int __dev_change_net_namespace(struct net_device *dev, struct net *net,
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index ae2c6a3cec5d..92ad75549e9c 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -12,21 +12,22 @@
 extern int rtnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, u32 group, int echo);
 extern int rtnl_unicast(struct sk_buff *skb, struct net *net, u32 pid);
 extern void rtnl_notify(struct sk_buff *skb, struct net *net, u32 pid,
-			u32 group, struct nlmsghdr *nlh, gfp_t flags);
+			u32 group, const struct nlmsghdr *nlh, gfp_t flags);
 extern void rtnl_set_sk_err(struct net *net, u32 group, int error);
 extern int rtnetlink_put_metrics(struct sk_buff *skb, u32 *metrics);
 extern int rtnl_put_cacheinfo(struct sk_buff *skb, struct dst_entry *dst,
 			      u32 id, long expires, u32 error);
 
-void rtmsg_ifinfo(int type, struct net_device *dev, unsigned change, gfp_t flags);
+void rtmsg_ifinfo(int type, struct net_device *dev, unsigned int change, gfp_t flags,
+		  u32 portid, const struct nlmsghdr *nlh);
 void rtmsg_ifinfo_newnet(int type, struct net_device *dev, unsigned int change,
 			 gfp_t flags, int *new_nsid, int new_ifindex);
 struct sk_buff *rtmsg_ifinfo_build_skb(int type, struct net_device *dev,
 				       unsigned change, u32 event,
 				       gfp_t flags, int *new_nsid,
-				       int new_ifindex);
+				       int new_ifindex, u32 portid, u32 seq);
 void rtmsg_ifinfo_send(struct sk_buff *skb, struct net_device *dev,
-		       gfp_t flags);
+		       gfp_t flags, u32 portid, const struct nlmsghdr *nlh);
 
 
 /* RTNL is used as a global lock for all changes to network configuration  */
diff --git a/include/net/netlink.h b/include/net/netlink.h
index 4418b1981e31..c65ea95e2f4a 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -899,6 +899,17 @@ static inline int nlmsg_report(const struct nlmsghdr *nlh)
 	return nlh ? !!(nlh->nlmsg_flags & NLM_F_ECHO) : 0;
 }
 
+/**
+ * nlmsg_seq - return the seq number of netlink message
+ * @nlh: netlink message header
+ *
+ * Returns 0 if netlink message is NULL
+ */
+static inline u32 nlmsg_seq(const struct nlmsghdr *nlh)
+{
+	return nlh ? nlh->nlmsg_seq : 0;
+}
+
 /**
  * nlmsg_for_each_attr - iterate over a stream of attributes
  * @pos: loop counter, set to current attribute
diff --git a/include/net/rtnetlink.h b/include/net/rtnetlink.h
index bf8bb3357825..cd94f65dc2a9 100644
--- a/include/net/rtnetlink.h
+++ b/include/net/rtnetlink.h
@@ -187,7 +187,8 @@ struct net_device *rtnl_create_link(struct net *net, const char *ifname,
 				    struct nlattr *tb[],
 				    struct netlink_ext_ack *extack);
 int rtnl_delete_link(struct net_device *dev);
-int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm);
+int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm,
+			u32 portid, const struct nlmsghdr *nlh);
 
 int rtnl_nla_parse_ifla(struct nlattr **tb, const struct nlattr *head, int len,
 			struct netlink_ext_ack *exterr);
diff --git a/net/core/dev.c b/net/core/dev.c
index fff62068a53d..ce61ebaaae19 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;
@@ -10849,7 +10850,7 @@ 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, 0, 0);
 
 		/*
 		 *	Flush the unicast and multicast chains
@@ -10864,7 +10865,7 @@ 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, 0, NULL);
 
 		/* Notifier chain MUST detach us all upper devices. */
 		WARN_ON(netdev_has_any_upper_dev(dev));
@@ -11042,7 +11043,7 @@ 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;
diff --git a/net/core/dev.h b/net/core/dev.h
index cbb8a925175a..6b3c7302f570 100644
--- a/net/core/dev.h
+++ b/net/core/dev.h
@@ -88,6 +88,10 @@ int dev_change_carrier(struct net_device *dev, bool new_carrier);
 
 void __dev_set_rx_mode(struct net_device *dev);
 
+void __dev_notify_flags(struct net_device *dev, unsigned int old_flags,
+			unsigned int gchanges, u32 portid,
+			const struct nlmsghdr *nlh);
+
 static inline void netif_set_gso_max_size(struct net_device *dev,
 					  unsigned int size)
 {
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 74864dc46a7e..c9dd9730f3c6 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -760,7 +760,7 @@ int rtnl_unicast(struct sk_buff *skb, struct net *net, u32 pid)
 EXPORT_SYMBOL(rtnl_unicast);
 
 void rtnl_notify(struct sk_buff *skb, struct net *net, u32 pid, u32 group,
-		 struct nlmsghdr *nlh, gfp_t flags)
+		 const struct nlmsghdr *nlh, gfp_t flags)
 {
 	struct sock *rtnl = net->rtnl;
 
@@ -3180,7 +3180,8 @@ static int rtnl_dellink(struct sk_buff *skb, struct nlmsghdr *nlh,
 	return err;
 }
 
-int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm)
+int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm,
+			u32 portid, const struct nlmsghdr *nlh)
 {
 	unsigned int old_flags;
 	int err;
@@ -3194,10 +3195,10 @@ int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm)
 	}
 
 	if (dev->rtnl_link_state == RTNL_LINK_INITIALIZED) {
-		__dev_notify_flags(dev, old_flags, (old_flags ^ dev->flags));
+		__dev_notify_flags(dev, old_flags, (old_flags ^ dev->flags), portid, nlh);
 	} else {
 		dev->rtnl_link_state = RTNL_LINK_INITIALIZED;
-		__dev_notify_flags(dev, old_flags, ~0U);
+		__dev_notify_flags(dev, old_flags, ~0U, portid, nlh);
 	}
 	return 0;
 }
@@ -3369,7 +3370,7 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
 		goto out;
 	}
 
-	err = rtnl_configure_link(dev, ifm);
+	err = rtnl_configure_link(dev, ifm, 0, NULL);
 	if (err < 0)
 		goto out_unregister;
 	if (link_net) {
@@ -3896,7 +3897,7 @@ static int rtnl_dump_all(struct sk_buff *skb, struct netlink_callback *cb)
 struct sk_buff *rtmsg_ifinfo_build_skb(int type, struct net_device *dev,
 				       unsigned int change,
 				       u32 event, gfp_t flags, int *new_nsid,
-				       int new_ifindex)
+				       int new_ifindex, u32 portid, u32 seq)
 {
 	struct net *net = dev_net(dev);
 	struct sk_buff *skb;
@@ -3907,7 +3908,7 @@ struct sk_buff *rtmsg_ifinfo_build_skb(int type, struct net_device *dev,
 		goto errout;
 
 	err = rtnl_fill_ifinfo(skb, dev, dev_net(dev),
-			       type, 0, 0, change, 0, 0, event,
+			       type, portid, seq, change, 0, 0, event,
 			       new_nsid, new_ifindex, -1, flags);
 	if (err < 0) {
 		/* -EMSGSIZE implies BUG in if_nlmsg_size() */
@@ -3922,16 +3923,18 @@ struct sk_buff *rtmsg_ifinfo_build_skb(int type, struct net_device *dev,
 	return NULL;
 }
 
-void rtmsg_ifinfo_send(struct sk_buff *skb, struct net_device *dev, gfp_t flags)
+void rtmsg_ifinfo_send(struct sk_buff *skb, struct net_device *dev, gfp_t flags,
+		       u32 portid, const struct nlmsghdr *nlh)
 {
 	struct net *net = dev_net(dev);
 
-	rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, flags);
+	rtnl_notify(skb, net, portid, RTNLGRP_LINK, nlh, flags);
 }
 
 static void rtmsg_ifinfo_event(int type, struct net_device *dev,
 			       unsigned int change, u32 event,
-			       gfp_t flags, int *new_nsid, int new_ifindex)
+			       gfp_t flags, int *new_nsid, int new_ifindex,
+			       u32 portid, const struct nlmsghdr *nlh)
 {
 	struct sk_buff *skb;
 
@@ -3939,23 +3942,23 @@ static void rtmsg_ifinfo_event(int type, struct net_device *dev,
 		return;
 
 	skb = rtmsg_ifinfo_build_skb(type, dev, change, event, flags, new_nsid,
-				     new_ifindex);
+				     new_ifindex, portid, nlmsg_seq(nlh));
 	if (skb)
-		rtmsg_ifinfo_send(skb, dev, flags);
+		rtmsg_ifinfo_send(skb, dev, flags, portid, nlh);
 }
 
 void rtmsg_ifinfo(int type, struct net_device *dev, unsigned int change,
-		  gfp_t flags)
+		  gfp_t flags, u32 portid, const struct nlmsghdr *nlh)
 {
 	rtmsg_ifinfo_event(type, dev, change, rtnl_get_event(0), flags,
-			   NULL, 0);
+			   NULL, 0, portid, nlh);
 }
 
 void rtmsg_ifinfo_newnet(int type, struct net_device *dev, unsigned int change,
 			 gfp_t flags, int *new_nsid, int new_ifindex)
 {
 	rtmsg_ifinfo_event(type, dev, change, rtnl_get_event(0), flags,
-			   new_nsid, new_ifindex);
+			   new_nsid, new_ifindex, 0, NULL);
 }
 
 static int nlmsg_populate_fdb_fill(struct sk_buff *skb,
@@ -6140,7 +6143,7 @@ static int rtnetlink_event(struct notifier_block *this, unsigned long event, voi
 	case NETDEV_CHANGELOWERSTATE:
 	case NETDEV_CHANGE_TX_QUEUE_LEN:
 		rtmsg_ifinfo_event(RTM_NEWLINK, dev, 0, rtnl_get_event(event),
-				   GFP_KERNEL, NULL, 0);
+				   GFP_KERNEL, NULL, 0, 0, NULL);
 		break;
 	default:
 		break;
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index f866d6282b2b..d8ee5238c395 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -1665,7 +1665,7 @@ struct net_device *gretap_fb_dev_create(struct net *net, const char *name,
 	if (err)
 		goto out;
 
-	err = rtnl_configure_link(dev, NULL);
+	err = rtnl_configure_link(dev, NULL, 0, NULL);
 	if (err < 0)
 		goto out;
 
-- 
2.37.3

[PATCHv7 net-next 2/4] net: add new helper unregister_netdevice_many_notify

[Hangbin Liu]

Add new helper unregister_netdevice_many_notify(), pass netlink message
header and portid, which could be used to notify userspace when flag
NLM_F_ECHO is set.

Make the unregister_netdevice_many() as a wrapper of new function
unregister_netdevice_many_notify().

Suggested-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 net/core/dev.c | 27 +++++++++++++++++----------
 net/core/dev.h |  3 +++
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index ce61ebaaae19..c35af83d089e 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -10781,14 +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);
@@ -10850,7 +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, 0, 0);
+						     GFP_KERNEL, NULL, 0,
+						     portid, nlmsg_seq(nlh));
 
 		/*
 		 *	Flush the unicast and multicast chains
@@ -10865,7 +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, 0, NULL);
+			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));
@@ -10888,6 +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);
 
 /**
diff --git a/net/core/dev.h b/net/core/dev.h
index 6b3c7302f570..814ed5b7b960 100644
--- a/net/core/dev.h
+++ b/net/core/dev.h
@@ -92,6 +92,9 @@ void __dev_notify_flags(struct net_device *dev, unsigned int old_flags,
 			unsigned int gchanges, u32 portid,
 			const struct nlmsghdr *nlh);
 
+void unregister_netdevice_many_notify(struct list_head *head,
+				      u32 portid, const struct nlmsghdr *nlh);
+
 static inline void netif_set_gso_max_size(struct net_device *dev,
 					  unsigned int size)
 {
-- 
2.37.3

[PATCHv7 net-next 3/4] rtnetlink: Honour NLM_F_ECHO flag in rtnl_newlink_create

[Hangbin Liu]

This patch pass the netlink header message in rtnl_newlink_create() to
the new updated rtnl_configure_link(), so that the kernel could reply
unicast when userspace set NLM_F_ECHO flag to request the new created
interface info.

Suggested-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 net/core/rtnetlink.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index c9dd9730f3c6..839ff8b7eadc 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3312,11 +3312,13 @@ 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,
+			       const struct nlmsghdr *nlh,
 			       struct nlattr **tb, struct nlattr **data,
 			       struct netlink_ext_ack *extack)
 {
 	unsigned char name_assign_type = NET_NAME_USER;
 	struct net *net = sock_net(skb->sk);
+	u32 portid = NETLINK_CB(skb).portid;
 	struct net *dest_net, *link_net;
 	struct net_device *dev;
 	char ifname[IFNAMSIZ];
@@ -3370,7 +3372,7 @@ static int rtnl_newlink_create(struct sk_buff *skb, struct ifinfomsg *ifm,
 		goto out;
 	}
 
-	err = rtnl_configure_link(dev, ifm, 0, NULL);
+	err = rtnl_configure_link(dev, ifm, portid, nlh);
 	if (err < 0)
 		goto out_unregister;
 	if (link_net) {
@@ -3579,7 +3581,7 @@ static int __rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
 		return -EOPNOTSUPP;
 	}
 
-	return rtnl_newlink_create(skb, ifm, ops, tb, data, extack);
+	return rtnl_newlink_create(skb, ifm, ops, nlh, tb, data, extack);
 }
 
 static int rtnl_newlink(struct sk_buff *skb, struct nlmsghdr *nlh,
-- 
2.37.3

[PATCHv7 net-next 4/4] rtnetlink: Honour NLM_F_ECHO flag in rtnl_delete_link

[Hangbin Liu]

This patch use the new helper unregister_netdevice_many_notify() for
rtnl_delete_link(), so that the kernel could reply unicast when userspace
 set NLM_F_ECHO flag to request the new created interface info.

At the same time, the parameters of rtnl_delete_link() need to be updated
since we need nlmsghdr and portid info.

Suggested-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
---
 include/net/rtnetlink.h        | 2 +-
 net/core/rtnetlink.c           | 7 ++++---
 net/openvswitch/vport-geneve.c | 2 +-
 net/openvswitch/vport-gre.c    | 2 +-
 net/openvswitch/vport-netdev.c | 2 +-
 net/openvswitch/vport-vxlan.c  | 2 +-
 6 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/include/net/rtnetlink.h b/include/net/rtnetlink.h
index cd94f65dc2a9..d9076a7a430c 100644
--- a/include/net/rtnetlink.h
+++ b/include/net/rtnetlink.h
@@ -186,7 +186,7 @@ struct net_device *rtnl_create_link(struct net *net, const char *ifname,
 				    const struct rtnl_link_ops *ops,
 				    struct nlattr *tb[],
 				    struct netlink_ext_ack *extack);
-int rtnl_delete_link(struct net_device *dev);
+int rtnl_delete_link(struct net_device *dev, u32 portid, const struct nlmsghdr *nlh);
 int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm,
 			u32 portid, const struct nlmsghdr *nlh);
 
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 839ff8b7eadc..d2f27548fc0b 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -3110,7 +3110,7 @@ static int rtnl_group_dellink(const struct net *net, int group)
 	return 0;
 }
 
-int rtnl_delete_link(struct net_device *dev)
+int rtnl_delete_link(struct net_device *dev, u32 portid, const struct nlmsghdr *nlh)
 {
 	const struct rtnl_link_ops *ops;
 	LIST_HEAD(list_kill);
@@ -3120,7 +3120,7 @@ int rtnl_delete_link(struct net_device *dev)
 		return -EOPNOTSUPP;
 
 	ops->dellink(dev, &list_kill);
-	unregister_netdevice_many(&list_kill);
+	unregister_netdevice_many_notify(&list_kill, portid, nlh);
 
 	return 0;
 }
@@ -3130,6 +3130,7 @@ static int rtnl_dellink(struct sk_buff *skb, struct nlmsghdr *nlh,
 			struct netlink_ext_ack *extack)
 {
 	struct net *net = sock_net(skb->sk);
+	u32 portid = NETLINK_CB(skb).portid;
 	struct net *tgt_net = net;
 	struct net_device *dev = NULL;
 	struct ifinfomsg *ifm;
@@ -3171,7 +3172,7 @@ static int rtnl_dellink(struct sk_buff *skb, struct nlmsghdr *nlh,
 		goto out;
 	}
 
-	err = rtnl_delete_link(dev);
+	err = rtnl_delete_link(dev, portid, nlh);
 
 out:
 	if (netnsid >= 0)
diff --git a/net/openvswitch/vport-geneve.c b/net/openvswitch/vport-geneve.c
index 89a8e1501809..b10e1602c6b1 100644
--- a/net/openvswitch/vport-geneve.c
+++ b/net/openvswitch/vport-geneve.c
@@ -91,7 +91,7 @@ static struct vport *geneve_tnl_create(const struct vport_parms *parms)
 
 	err = dev_change_flags(dev, dev->flags | IFF_UP, NULL);
 	if (err < 0) {
-		rtnl_delete_link(dev);
+		rtnl_delete_link(dev, 0, NULL);
 		rtnl_unlock();
 		ovs_vport_free(vport);
 		goto error;
diff --git a/net/openvswitch/vport-gre.c b/net/openvswitch/vport-gre.c
index e6b5e76a962a..4014c9b5eb79 100644
--- a/net/openvswitch/vport-gre.c
+++ b/net/openvswitch/vport-gre.c
@@ -57,7 +57,7 @@ static struct vport *gre_tnl_create(const struct vport_parms *parms)
 
 	err = dev_change_flags(dev, dev->flags | IFF_UP, NULL);
 	if (err < 0) {
-		rtnl_delete_link(dev);
+		rtnl_delete_link(dev, 0, NULL);
 		rtnl_unlock();
 		ovs_vport_free(vport);
 		return ERR_PTR(err);
diff --git a/net/openvswitch/vport-netdev.c b/net/openvswitch/vport-netdev.c
index 2f61d5bdce1a..903537a5da22 100644
--- a/net/openvswitch/vport-netdev.c
+++ b/net/openvswitch/vport-netdev.c
@@ -172,7 +172,7 @@ void ovs_netdev_tunnel_destroy(struct vport *vport)
 	 * if it's not already shutting down.
 	 */
 	if (vport->dev->reg_state == NETREG_REGISTERED)
-		rtnl_delete_link(vport->dev);
+		rtnl_delete_link(vport->dev, 0, NULL);
 	netdev_put(vport->dev, &vport->dev_tracker);
 	vport->dev = NULL;
 	rtnl_unlock();
diff --git a/net/openvswitch/vport-vxlan.c b/net/openvswitch/vport-vxlan.c
index 188e9c1360a1..0b881b043bcf 100644
--- a/net/openvswitch/vport-vxlan.c
+++ b/net/openvswitch/vport-vxlan.c
@@ -120,7 +120,7 @@ static struct vport *vxlan_tnl_create(const struct vport_parms *parms)
 
 	err = dev_change_flags(dev, dev->flags | IFF_UP, NULL);
 	if (err < 0) {
-		rtnl_delete_link(dev);
+		rtnl_delete_link(dev, 0, NULL);
 		rtnl_unlock();
 		ovs_vport_free(vport);
 		goto error;
-- 
2.37.3

Re: [PATCHv7 net-next 0/4] rtnetlink: Honour NLM_F_ECHO flag in rtnl_{new, del}link

[Guillaume Nault]

On Fri, Oct 28, 2022 at 04:42:20AM -0400, Hangbin Liu wrote:
> 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.

Reviewed-by: Guillaume Nault <gnault@redhat.com>

Thanks Hangbin!

Re: [PATCHv7 net-next 0/4] rtnetlink: Honour NLM_F_ECHO flag in rtnl_{new, del}link

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (master)
by Jakub Kicinski <kuba@kernel.org>:

On Fri, 28 Oct 2022 04:42:20 -0400 you wrote:
> 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).
> 
> [...]

Here is the summary with links:
  - [PATCHv7,net-next,1/4] rtnetlink: pass netlink message header and portid to rtnl_configure_link()
    https://git.kernel.org/netdev/net-next/c/1d997f101307
  - [PATCHv7,net-next,2/4] net: add new helper unregister_netdevice_many_notify
    https://git.kernel.org/netdev/net-next/c/77f4aa9a2a17
  - [PATCHv7,net-next,3/4] rtnetlink: Honour NLM_F_ECHO flag in rtnl_newlink_create
    https://git.kernel.org/netdev/net-next/c/d88e136cab37
  - [PATCHv7,net-next,4/4] rtnetlink: Honour NLM_F_ECHO flag in rtnl_delete_link
    https://git.kernel.org/netdev/net-next/c/f3a63cce1b4f

You are awesome, thank you!
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