Messages in this thread | | | From | Roland Dreier <> | Subject | Re: patch: support long (above 14 bytes) HW addresses in arp_ioctl | Date | Mon, 03 Nov 2008 15:53:26 -0800 |
| |
[netdev added to cc list]
> In arp_req_get() in net/arp.c, there is code: > > memcpy(r->arp_ha.sa_data, neigh->ha, dev->addr_len); > > dev->addr_len can be larger than size of > r->arp_ha.sa_data. Inititally, I thought it would corrupt kernel > stack. I was wrong, since r still has enough space not to overflow > even for the largest HW address (32 bytes). It would corrupt the data > structure though, and that corrupted reply would be propagated to > user. > > There is a similar situation in arp_req_set(), where a "junk" arp > entry will be set if dev->addr_len is larger that 14 bytes. > > At the very minimum, both arp_req_set() and arp_req_get() should > return error (-EINVAL), and not return junk or set junk. Truncated > /proc/net/arp output should also be fixed.
The EINVAL return makes sense; I'm not sure /proc/net/arp is important enough to fix. I guess it depends on the impact of the fix.
> I was not aware that rtnetlink is capable of doing things like arp > table or interface manipulation (like netdevice ioctls). My > applications needs to be able to manipulate arp cache for large macs, > and I do not mind recompiling by adding a flag. I do not mind fixing > arp cli to use this either (venerable arp does use arp_ioctl). And > there are many many legacy solutions that use arp_ioctl() in programs > and arp utility in scripts. Consider porting those to infiniband. > > Will rtnetlink work for any net_device (like netdevice ioctls do) for > ARP and interface configurations calls or does it require special > support in net_device itself? Any possible problems with rtnetlink?
rtnetlink is the preferred modern interface between userspace and kernel for networking information. There is also the "iproute2" package that provides a good command line interface that is capable of handling IPoIB addresses. For example:
$ ip addr show dev ib1 5: ib1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 2044 qdisc pfifo_fast state UP qlen 256 link/infiniband 80:00:00:48:fe:80:00:00:00:00:00:00:00:02:c9:03:00:00:01:65 brd 00:ff:ff:ff:ff:12:40:1b:ff:ff:00:00:00:00:00:00:ff:ff:ff:ff inet 192.168.145.74/24 brd 192.168.145.255 scope global ib1 inet6 fe80::202:c903:0:165/64 scope link valid_lft forever preferred_lft forever
$ ip neigh 192.168.145.73 dev ib1 lladdr 80:00:00:48:fe:80:00:00:00:00:00:00:00:02:c9:03:00:00:01:30 STALE 172.29.224.1 dev eth0 lladdr 00:00:0c:07:ac:e0 REACHABLE
and so on.
- R.
| |