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 <[email protected]> Signed-off-by: David S. Miller <[email protected]>
raspberrypi · Mar 4, 2009 · 0c5c2d3 · 0c5c2d3
1 parent fc1f9ea
commit 0c5c2d3
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Showing 2 changed files with 6 additions and 1 deletion.
diff --git a/include/linux/neighbour.h b/include/linux/neighbour.h
@@ -31,6 +31,7 @@ enum
  *	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
@@ -1654,7 +1654,11 @@ static int neigh_add(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 				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;
 	}