net: network device name ifalias support

This patch add support for keeping an additional character alias
associated with an network interface. This is useful for maintaining
the SNMP ifAlias value which is a user defined value. Routers use this
to hold information like which circuit or line it is connected to. It
is just an arbitrary text label on the network device.

There are two exposed interfaces with this patch, the value can be
read/written either via netlink or sysfs.

This could be maintained just by the snmp daemon, but it is more
generally useful for other management tools, and the kernel is good
place to act as an agreed upon interface to store it.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 5 insertions, 0 deletions

diff --git a/include/linux/if.h b/include/linux/if.h
index 5c9d1fa93fef..65246846c844 100644
--- a/include/linux/if.h
+++ b/include/linux/if.h
@@ -24,6 +24,7 @@
 #include <linux/compiler.h>             /* for "__user" et al           */
 
 #define IFNAMSIZ        16
+#define IFALIASZ        256
 #include <linux/hdlc/ioctl.h>
 
 /* Standard interface flags (netdevice->flags). */
diff --git a/include/linux/if_link.h b/include/linux/if_link.h
index 84c3492ae5cb..f9032c88716a 100644
--- a/include/linux/if_link.h
+++ b/include/linux/if_link.h
@@ -79,6 +79,7 @@ enum
         IFLA_LINKINFO,
 #define IFLA_LINKINFO IFLA_LINKINFO
         IFLA_NET_NS_PID,
+        IFLA_IFALIAS,
         __IFLA_MAX
 };
 
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 488c56e649b5..d675df08b946 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -471,6 +471,8 @@ struct net_device
         char                    name[IFNAMSIZ];
         /* device name hash chain */
         struct hlist_node       name_hlist;
+        /* snmp alias */
+        char                    *ifalias;
 
         /*
          *      I/O specific fields
@@ -1224,6 +1226,7 @@ extern int		dev_ethtool(struct net *net, struct ifreq *);
 extern unsigned         dev_get_flags(const struct net_device *);
 extern int              dev_change_flags(struct net_device *, unsigned);
 extern int              dev_change_name(struct net_device *, char *);
+extern int              dev_set_alias(struct net_device *, const char *, size_t);
 extern int              dev_change_net_namespace(struct net_device *,
                                                  struct net *, const char *);
 extern int              dev_set_mtu(struct net_device *, int);