[openib-general] Re: RFC userspace CMA

[Caitlin Bestler]

> -----Original Message-----
> From: openib-general-bounces at openib.org 
> [mailto:openib-general-bounces at openib.org] On Behalf Of 
> Michael S. Tsirkin
> Sent: Wednesday, October 26, 2005 1:44 PM
> To: Sean Hefty
> Cc: openib
> Subject: [openib-general] Re: RFC userspace CMA
> 
> 
> But I mean, we can already send ARP packets from userspace, cant we?
> 

No, non-privileged users are not allowed to modify the ARP table,
open /dev/arp or to send raw Ethernet.

You can use ARP to query from non-privileged userspace. But nothing
beyond that. If you check the man page you'll also note that the ARP
daemon specifically listens to ensure that nobody else is impersonating
it. That's exactly the type of safety check that is blocked if IP
addresses are passed via private data where the fact that the data
is an IP address is not defined in the wire protocol.