[PATCH net-next v1 2/5] if_addr: add IFA_IF_NETNSID

[Christian Brauner <christian@brauner.io>]

This adds a new IFA_IF_NETNSID property to be used by address families such
as PF_INET and PF_INET6.
The IFA_IF_NETNSID property can be used to send a network namespace
identifier as part of a request. If a IFA_IF_NETNSID property is identified
it will be used to retrieve the target network namespace in which the
request is to be made.

Signed-off-by: Christian Brauner <christian@brauner.io>
Cc: Jiri Benc <jbenc@redhat.com>
Cc: Nicolas Dichtel <nicolas.dichtel@6wind.com>
---
v0->v1:
- unchanged
  Note, I did not change the property name to IFA_TARGET_NSID as there
  was no clear agreement what would be preferred. My personal preference
  is to keep the IFA_IF_NETNSID name because it aligns naturally with
  the IFLA_IF_NETNSID property for RTM_*LINK requests. Jiri seems to
  prefer this name too.
  However, if there is agreement that another property name makes more
  sense I'm happy to send a v2 that changes this.
---
 include/uapi/linux/if_addr.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/uapi/linux/if_addr.h b/include/uapi/linux/if_addr.h
index ebaf5701c9db..0e0cd588cac0 100644
--- a/include/uapi/linux/if_addr.h
+++ b/include/uapi/linux/if_addr.h
@@ -34,6 +34,7 @@ enum {
 	IFA_MULTICAST,
 	IFA_FLAGS,
 	IFA_RT_PRIORITY,  /* u32, priority/metric for prefix route */
+	IFA_IF_NETNSID,
 	__IFA_MAX,
 };
 
-- 
2.17.1