sysfs: add attribute to indicate hw address assignment type

Add addr_assign_type to struct net_device and expose it via sysfs.
This new attribute has the purpose of giving user-space the ability to
distinguish between different assignment types of MAC addresses.

For example user-space can treat NICs with randomly generated MAC
addresses differently than NICs that have permanent (locally assigned)
MAC addresses.
For the former udev could write a persistent net rule by matching the
device path instead of the MAC address.
There's also the case of devices that 'steal' MAC addresses from slave
devices. In which it is also be beneficial for user-space to be aware
of the fact.

This patch also introduces a helper function to assist adoption of
drivers that generate MAC addresses randomly.

Signed-off-by: Stefan Assmann <sassmann@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
index 3d7a6687d247c32577cf6bad2f7cb483fd434c51..848480bc2bf93846b14e43c0c94493cb2109f889 100644 (file)
--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h
@@ -126,6 +126,20 @@ static inline void random_ether_addr(u8 *addr)
        addr [0] |= 0x02;       /* set local assignment bit (IEEE802) */
 }
 
+/**
+ * dev_hw_addr_random - Create random MAC and set device flag
+ * @dev: pointer to net_device structure
+ * @addr: Pointer to a six-byte array containing the Ethernet address
+ *
+ * Generate random MAC to be used by a device and set addr_assign_type
+ * so the state can be read by sysfs and be used by udev.
+ */
+static inline void dev_hw_addr_random(struct net_device *dev, u8 *hwaddr)
+{
+       dev->addr_assign_type |= NET_ADDR_RANDOM;
+       random_ether_addr(hwaddr);
+}
+
 /**
  * compare_ether_addr - Compare two Ethernet addresses
  * @addr1: Pointer to a six-byte array containing the Ethernet address

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index b6262898ece06ffaf9de1ed0b80e6fae15c364f8..1bca6171b1aa2d03691af0de3c89216a1977d9a6 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -66,6 +66,11 @@ struct wireless_dev;
 #define HAVE_FREE_NETDEV               /* free_netdev() */
 #define HAVE_NETDEV_PRIV               /* netdev_priv() */
 
+/* hardware address assignment types */
+#define NET_ADDR_PERM          0       /* address is permanent (default) */
+#define NET_ADDR_RANDOM                1       /* address is generated randomly */
+#define NET_ADDR_STOLEN                2       /* address is stolen from other device */
+
 /* Backlog congestion levels */
 #define NET_RX_SUCCESS         0       /* keep 'em coming, baby */
 #define NET_RX_DROP            1       /* packet dropped */
@@ -919,6 +924,7 @@ struct net_device {
 
        /* Interface address info. */
        unsigned char           perm_addr[MAX_ADDR_LEN]; /* permanent hw address */
+       unsigned char           addr_assign_type; /* hw address assignment type */
        unsigned char           addr_len;       /* hardware address length      */
        unsigned short          dev_id;         /* for shared network cards */
 

diff --git a/net/core/net-sysfs.c b/net/core/net-sysfs.c
index d2b596537d416f2b0f3fd3daaae5e9f9cc931be4..af4dfbadf2a09ea496653990ae8e1da823a059e1 100644 (file)
--- a/net/core/net-sysfs.c
+++ b/net/core/net-sysfs.c
@@ -95,6 +95,7 @@ static ssize_t netdev_store(struct device *dev, struct device_attribute *attr,
 }
 
 NETDEVICE_SHOW(dev_id, fmt_hex);
+NETDEVICE_SHOW(addr_assign_type, fmt_dec);
 NETDEVICE_SHOW(addr_len, fmt_dec);
 NETDEVICE_SHOW(iflink, fmt_dec);
 NETDEVICE_SHOW(ifindex, fmt_dec);
@@ -295,6 +296,7 @@ static ssize_t show_ifalias(struct device *dev,
 }
 
 static struct device_attribute net_class_attributes[] = {
+       __ATTR(addr_assign_type, S_IRUGO, show_addr_assign_type, NULL),
        __ATTR(addr_len, S_IRUGO, show_addr_len, NULL),
        __ATTR(dev_id, S_IRUGO, show_dev_id, NULL),
        __ATTR(ifalias, S_IRUGO | S_IWUSR, show_ifalias, store_ifalias),