Hello
Gary < gary.manchon (at) gmail.com > found a problem where he was unable
to recover from a bad network interface configuration
(ifconfig eth0 127.0.0.1), ref
http://www.uwsg.iu.edu/hypermail/linux/net/0801.2/0009.html
This was confirmed by several people.
I suspect that the problem might be this code in net/ipv4/devinet.c ,
which sets ifa_scope to RT_SCOPE_HOST if you configure a loopback
address (127/8) on any interface. I guess it's there to protect us from
sending packets with a loopback source address, which woulnd't look too
good:
static int inet_set_ifa(struct net_device *dev, struct in_ifaddr *ifa)
{
struct in_device *in_dev = __in_dev_get_rtnl(dev);
ASSERT_RTNL();
if (!in_dev) {
inet_free_ifa(ifa);
return -ENOBUFS;
}
ipv4_devconf_setall(in_dev);
if (ifa->ifa_dev != in_dev) {
BUG_TRAP(!ifa->ifa_dev);
in_dev_hold(in_dev);
ifa->ifa_dev = in_dev;
}
if (LOOPBACK(ifa->ifa_local))
ifa->ifa_scope = RT_SCOPE_HOST;
return inet_insert_ifa(ifa);
}
The real problem is that there's never anything resetting this scope if
you change the address later. This patch adds scope reset when changing
the address.
We set the scope to RT_SCOPE_HOST if an IPv4 interface is configured with a
loopback address (127/8). This prevents the interface from sending packets
out the wire. This patch resets the scope if the address is changed again,
to restore normal functionality.
Signed-off-by: Bjorn Mork <[EMAIL PROTECTED]>
devinet.c | 1 +
1 file changed, 1 insertion(+)
--- linux-2.6.24-rc8.orig/net/ipv4/devinet.c 2008-01-16 05:22:48.000000000 +0100
+++ linux-2.6.24-rc8/net/ipv4/devinet.c 2008-01-23 19:17:30.000000000 +0100
@@ -753,6 +753,7 @@
inet_del_ifa(in_dev, ifap, 0);
ifa->ifa_broadcast = 0;
ifa->ifa_anycast = 0;
+ ifa->ifa_scope = 0;
}
ifa->ifa_address = ifa->ifa_local = sin->sin_addr.s_addr;
Bjørn
