From mboxrd@z Thu Jan  1 00:00:00 1970
From: Alexey Toptygin <alexeyt@freeshell.org>
Subject: Re: sysfs vs. d80211 configuration
Date: Mon, 14 Aug 2006 23:05:15 +0000 (UTC)
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References: <44E07662.8070506@sipsolutions.net>
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To: Johannes Berg <johannes@sipsolutions.net>
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On Mon, 14 Aug 2006, Johannes Berg wrote:

> In my seemingly never-ending quest to actually use the d80211 stack for 
> something useful I just wanted to write a small setuid tool that:
> * creates and opens a new monitor interface
> * drops priviledges
> * ... does things with received frames ... (not interesting for this 
> discussion)
> * removes new monitor interface
>
> So I figured I'd just keep an fd open to 
> /sys/class/net/mymonitorinterface/remove_iface to which I could write the 
> interfaces name after I was done with it. However, when writing to that fd I 
> got -EACCESS because it checks for CAP_NET_ADMIN.

Why not have the tool create a monitor interface, open it, and fork; the 
child drops privileges and does the reading, and the parent wait(2)s for 
the child and removes the interface once it has collected the child?

 			Alexey