neigh: Allow for user space users of the neighbour table
Currently it is possible to do just about everything with the arp table
from user space except treat an entry like you are using it. To that end
implement and a flag NTF_USE that when set in a netwlink update request
treats the neighbour table entry like the kernel does on the output path.
This allows user space applications to share the kernel's arp cache.
Signed-off-by: Eric Biederman <ebiederm@aristanetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/neighbour.h b/include/linux/neighbour.h
index 8730d5d..12c9de1 100644
--- a/include/linux/neighbour.h
+++ b/include/linux/neighbour.h
@@ -31,6 +31,7 @@
* Neighbor Cache Entry Flags
*/
+#define NTF_USE 0x01
#define NTF_PROXY 0x08 /* == ATF_PUBL */
#define NTF_ROUTER 0x80
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 417b6d7..a1cbce7 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1654,7 +1654,11 @@
flags &= ~NEIGH_UPDATE_F_OVERRIDE;
}
- err = neigh_update(neigh, lladdr, ndm->ndm_state, flags);
+ if (ndm->ndm_flags & NTF_USE) {
+ neigh_event_send(neigh, NULL);
+ err = 0;
+ } else
+ err = neigh_update(neigh, lladdr, ndm->ndm_state, flags);
neigh_release(neigh);
goto out_dev_put;
}