netdev - Re: [PATCH] sysfs: Don't allow the creation of symlinks we can't remove

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Message-ID: <20100708211930.GA15385@kroah.com>
Date:	Thu, 8 Jul 2010 14:19:30 -0700
From:	Greg KH <greg@...ah.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	Greg KH <gregkh@...e.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	"Maciej W. Rozycki" <macro@...ux-mips.org>,
	Kay Sievers <kay.sievers@...y.org>,
	Johannes Berg <johannes@...solutions.net>,
	netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH] sysfs: Don't allow the creation of symlinks we can't
 remove

On Thu, Jul 08, 2010 at 09:31:24AM -0700, Eric W. Biederman wrote:
> 
> Recently my tagged sysfs support revealed a flaw in the device core
> that a few rare drivers are running into such that we don't always put
> network devices in a class subdirectory named net/.
> 
> Since we are not creating the class directory the network devices wind
> up in a non-tagged directory, but the symlinks to the network devices
> from /sys/class/net are in a tagged directory.  All of which works
> until we go to remove or rename the symlink.  When we remove or rename
> a symlink we look in the namespace of the target of the symlink.
> Since the target of the symlink is in a non-tagged sysfs directory we
> don't have a namespace to look in, and we fail to remove the symlink.
> 
> Detect this problem up front and simply don't create symlinks we won't
> be able to remove later.  This prevents symlink leakage and fails in
> a much clearer and more understandable way.

With this patch, how does the existing code fail as the drivers aren't
fixed up?

I like this change, just worried it will cause problems if it gets into
.35, without your RFC patch.  Will it?

thanks,

greg k-h
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