Re: [PATCH 2.6] dev.c: clear SIOCGIFHWADDR buffer if !dev->addr_len

[Matt Domsch <Matt_Domsch@xxxxxxxx>]

On Sun, Oct 31, 2004 at 10:44:33PM -0600, Matt Domsch wrote:
> I think -EOVERFLOW would be appropriate return for dev->addr_len >
> sizeof sa_data, yes?
> 
> I'd prefer though, that an "obsolete" function, be marked as such
> somehow (perhaps print a net_ratelimit()ed KERN_DEBUG message when
> it's called telling apps to move to rtnetlink), and that the behaviour
> for everything except overflow be consistent with the prior
> implementation, at least until such a time that all the apps in the
> distros are converted to rtnetlink.

How's this look?

This makes ioctl(SIOCIFHWADDR) behavior in 2.6 consistent with that of
previous kernels wherever possible.  It returns -EOVERFLOW if it can't
represent the address, zeros the data if dev->addr_len is zero, and
prints a KERN_DEBUG message telling people to fix their applications
to use rtnetlink.

Compiles on x86 and x86-64 cleanly.

Signed-off-by: Matt Domsch <Matt_Domsch@xxxxxxxx>


-- 
Matt Domsch
Sr. Software Engineer, Lead Engineer
Dell Linux Solutions linux.dell.com & www.dell.com/linux
Linux on Dell mailing lists @ http://lists.us.dell.com

===== net/core/dev.c 1.169 vs edited =====
--- 1.169/net/core/dev.c        2004-10-26 11:09:33 -05:00
+++ edited/net/core/dev.c       2004-11-01 11:20:25 -06:00
@@ -2375,8 +2375,16 @@
                        return dev_set_mtu(dev, ifr->ifr_mtu);
 
                case SIOCGIFHWADDR:
-                       memcpy(ifr->ifr_hwaddr.sa_data, dev->dev_addr,
-                              min(sizeof ifr->ifr_hwaddr.sa_data, (size_t) 
dev->addr_len));
+                       if (net_ratelimit())
+                               printk(KERN_DEBUG "Warning: %s uses obsolete 
ioctl(SIOCGIFHWADDR), please convert it to rtnetlink(3,7)\n", current->comm);
+
+                       if ((size_t) dev->addr_len > sizeof 
ifr->ifr_hwaddr.sa_data)
+                               return -EOVERFLOW;
+                       else if (!dev->addr_len)
+                               memset(ifr->ifr_hwaddr.sa_data, 0, sizeof 
ifr->ifr_hwaddr.sa_data);
+                       else
+                               memcpy(ifr->ifr_hwaddr.sa_data, dev->dev_addr,
+                                      min(sizeof ifr->ifr_hwaddr.sa_data, 
(size_t) dev->addr_len));
                        ifr->ifr_hwaddr.sa_family = dev->type;
                        return 0;