Generating a random ifid for devices with no L2 header
at all, allowing such devices to take part in IPv6
autoconfiguration. The tuntap driver is one example of
a driver where such an ifid would be useful.
Note that as there is no persistence, new addresses
will be generated every time an interface is brought up:
# ip -6 addr show dev tun0
8: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 state UNKNOWN qlen
500
inet6 fe80::eef2:111c:f270:92ba/64 scope link
valid_lft forever preferred_lft forever
# ip link set tun0 down
# ip link set tun0 up
# ip -6 addr show dev tun0
8: tun0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 state UNKNOWN qlen
500
inet6 fe80::eec0:48d0:6b52:8835/64 scope link
valid_lft forever preferred_lft forever
Signed-off-by: Bjørn Mork <bj...@mork.no>
---
I'm planning raw-ip support for the qmi_wwan driver. And
the feedback from primary users (ModemManager++) is that
a headerless netdev is preferred over a fake ethernet
device. The current plan is to model this after 'tun'
devices, using ARPHRD_NONE as type.
But these devices will need an IPv6 link local address for
full SLAAC support. I am therefore wondering if an approach
like this patch will be acceptable, or if I should look for
some other solution?
Bjørn
net/ipv6/addrconf.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index d84742f003a9..6cf3cae691a5 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -53,6 +53,7 @@
#include <linux/if_arp.h>
#include <linux/if_arcnet.h>
#include <linux/if_infiniband.h>
+#include <linux/random.h>
#include <linux/route.h>
#include <linux/inetdevice.h>
#include <linux/init.h>
@@ -2026,6 +2027,13 @@ static int addrconf_ifid_ip6tnl(u8 *eui, struct
net_device *dev)
return 0;
}
+static int addrconf_ifid_random(u8 *eui, struct net_device *dev)
+{
+ get_random_bytes(eui, 8);
+ eui[0] |= 0x02;
+ return 0;
+}
+
static int ipv6_generate_eui64(u8 *eui, struct net_device *dev)
{
switch (dev->type) {
@@ -2047,6 +2055,8 @@ static int ipv6_generate_eui64(u8 *eui, struct net_device
*dev)
return addrconf_ifid_ieee1394(eui, dev);
case ARPHRD_TUNNEL6:
return addrconf_ifid_ip6tnl(eui, dev);
+ case ARPHRD_NONE:
+ return addrconf_ifid_random(eui, dev);
}
return -1;
}
@@ -3069,8 +3079,8 @@ static void addrconf_dev_config(struct net_device *dev)
(dev->type != ARPHRD_IEEE802154) &&
(dev->type != ARPHRD_IEEE1394) &&
(dev->type != ARPHRD_TUNNEL6) &&
- (dev->type != ARPHRD_6LOWPAN)) {
- /* Alas, we support only Ethernet autoconfiguration. */
+ (dev->type != ARPHRD_6LOWPAN) &&
+ (dev->type != ARPHRD_NONE)) {
return;
}
--
2.1.4
--
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