Re: check_ack()
On Friday 21 November 2008 01:30:53 Lucas C. Villa Real wrote:
However, since netlink is a connectionless socket, once cannot infer
that the lack of an ACK means that the kernel didn't receive that
message.
That sounds like a design problem. Why would they even have an ACK if they
can't guarantee its delivery?
Similarly, in a very stressed system, one can just get -ENOBUFS when
attempting to get a reply, even though sendto() succeeded sending the
original message.
I think this sounds like a design problem in the netlink code.
So, at least in a scenario where Audit is a key component and
performance matters, wouldn't it make sense to just remove NLM_F_ACK
from outgoing messages and just let audit_send() use the return value
from sendto() to tell if the message has been sent instead?
The intent was to verify that all issued commands are in fact receieved so
that if they aren't, we can advise the user. I also believe the ACK is how we
find out that the command has bad parameters. So, I don't think its possible to
remove it. When an event fails to be sent, we need it to block the action
and/or otherwise log it into syslog. Otherwise you open up an avenue for
attacking systems. There are many people that consider auditing to be more
important than system availability.
-Steve