Re: 2.1.74 (.68+?) IP_ALIASing: BUG (ifconfig down)

A.N.Kuznetsov (kuznet@ms2.inr.ac.ru)
Wed, 24 Dec 1997 19:27:20 +0300 (MSK)


Hello!

> ifconfig eth0 10.1.16.0 netmask 255.255.240.0 up
> ifconfig eth0:0 10.1.31.254 up
> ifconfig eth0:0- 10.1.31.254
> /* yes, the above worked with the old ip_aliasing... */

It is OK. Only "ifconfig eth0:0-" disappeared,
it is supposed that "ifconfig eth0:0 down" does it,
though... :-) see below.

> ifconfig eth0:0 10.1.31.254 down
>
> why did eth0 go down too?!

Because of bug :-) Look at net/core/dev.c:

case SIOCGIFSLAVE:
case SIOCGIFMAP:
case SIOCGIFINDEX:
ret = dev_ifsioc(&ifr, cmd);
- if (!ret && copy_to_user(arg, &ifr, sizeof(struct ifreq)))
- return -EFAULT;
+ if (!ret) {
+#ifdef CONFIG_NET_ALIAS
+ if (colon)
+ *colon = ':';
+#endif
+ if (copy_to_user(arg, &ifr, sizeof(struct ifreq)))
+ return -EFAULT;
+ }
return ret;

Alexey Kuznetsov