[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: Could kernel copy memory between processes directly?
> Definitively no, everyone is saying that. If you haven't heard about
> synchronous messaging I encourage you to read:
> (section "Synchronous message passing")
> It's a bit similar to Mach messaging. The whole idea could be described
> like procedure call into another process.
> For shared memory processes must be trusted while for SRR the client
> (Sender) cannot break the server (Receiver), Important factor, isn't it :-)
You've said this before but not elaborated. Perhaps you do not
understand that a shared memory *segment* is just that - a relatively
small piece of memory that is mpaped into both processes. It does
NOT give either process access to all the other processes' memory,
so I'm not sure why you think trust is such a big issue. There is a
single integer key required to locate the smh segment AND filesystem-like
permissions to control access; if you need more secure authentication,
you can have a shared private key or whatever, exchanged through the SHM
segment. The Crypto libraries give you the mechanism and, if nobody
but your two apps know the policy, so much the better.
We are familiar with the general notion of synchronous message
passing. You are the one suggesting that our mechanisms are
inadequate; can we ask you to please familiarize yourself with the
details of standard UNIX shared memory, instead of taking QNX' word
that you can't do without their mechanism?