On Thu, 2007-07-05 at 09:53 -0400, jamal wrote: > This email captures the essence of the thread, so let me start here. > I dont know if i read well enough all the details, but i think i have a > good grasp of the discusion.
:)
> The DoS issue is applicable IMO to any IPC. i.e
> if i have access to sending to you, i can send you many messages and
> fill up your unix socket rcvq etc.
Yeah, good point.
> - In addition to the netlink sock open/close that Patrick mentioned, you
> can listen to generic netlink events on the accounting/task netlink and
> find out when processes are created/destroyed if that is useful. I
> couldnt tell why you needed to know this...
No, I need to know if a specific socket that I was using in the kernel
to communicate with a special userspace process is still open, but the
notifier seems to address that. I haven't tested it yet.
> Yes, this is TheWayItHasBeen(tm).
> Patrick had a patch a while back to allow for subscribing to higher
> groups because bind() has a similar issue in that it allows you only to
> subscribe to the first 32. So it is logical to fix connect, and sendmsg
> in a similar fashion.
Yeah, that's the sock opt.
> Fixing connect IMO would be a good first start because if you do
> connect() to the right group(s) before sendsmg() you could send
> to the correct group.
>
> > It would of course be possible to add a new sockopt
> > NETLINK_{SET,GET}_DST_GROUP,
>
> This maybe your best first starting option IMO. It will be in similar
> spirit to Patricks bind() fix.
Right.
> Iirc, i dont think we can do that anymore. But we can introduce a new
> scheme to allow for this. For example, could you not use CMSG to specify
> an explicit list of groups on sendmsg? IIRC, Patrick used CMSG to report
> on rcv which group a msg was received on.
I'll have to look into it. Patrick suggested this as well in the reply,
but I think it's not going to be too important to me right now,
depending on the outcome in the wireless discussion.
johannes
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