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From: Arjan van de Ven <arjan@infradead.org>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: matthew@wil.cx, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: DoS with POSIX file locks?
Date: Mon, 20 Mar 2006 14:13:43 +0100	[thread overview]
Message-ID: <1142860423.3114.41.camel@laptopd505.fenrus.org> (raw)
In-Reply-To: <E1FLJsF-0008A7-00@dorka.pomaz.szeredi.hu>

On Mon, 2006-03-20 at 13:52 +0100, Miklos Szeredi wrote:
> > Right.  Um.  I took it out back in March 2003 after enough people
> > convinced me it wasn't worth trying to account for all the memory
> > processes use, and the userbeans project would take care of it anyway.
> > Haha.
> > 
> > It's hard to fix the accounting.  You have to deal with one thread
> > allocating the lock, and then a different thread freeing it.  We never
> > actually accounted for posix locks (which are the ones we really needed
> > to!) and on occasion had current->locks go negative, with all kinds of
> > associated badness.
> 
> Things look fairly straightforward if the accounting is done in
> files_struct instead of task_struct. 

that's the wrong place; you can send fd's over unix sockets to other
processes....



the better solution is to account per user struct, and keep a pointer
(and a refcount) of that user struct inside your lock data somehow.



  reply	other threads:[~2006-03-20 13:13 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-03-20 11:41 DoS with POSIX file locks? Miklos Szeredi
2006-03-20 12:11 ` Matthew Wilcox
2006-03-20 12:19   ` Miklos Szeredi
2006-03-20 12:39     ` Matthew Wilcox
2006-03-20 12:52       ` Miklos Szeredi
2006-03-20 13:13         ` Arjan van de Ven [this message]
2006-03-20 13:24           ` Miklos Szeredi
2006-03-20 13:30             ` Arjan van de Ven
2006-03-20 13:39               ` Miklos Szeredi
2006-03-20 15:32         ` Matthew Wilcox
2006-03-20 16:41           ` Miklos Szeredi
2006-03-20 20:35             ` J. Bruce Fields
2006-03-21  6:38               ` Miklos Szeredi
2006-03-20 18:22           ` Trond Myklebust
2006-03-21  9:44             ` Miklos Szeredi
2006-03-21 17:28               ` Trond Myklebust
2006-03-21 17:58                 ` Miklos Szeredi
2006-03-21 18:16                   ` Trond Myklebust
2006-03-21 19:16                   ` Chris Wright
2006-03-22  6:21                     ` Miklos Szeredi
2006-03-22 11:12                       ` Trond Myklebust
2006-03-22 12:16                         ` Miklos Szeredi
2006-03-22 15:56                           ` Trond Myklebust
2006-03-22 16:34                             ` Miklos Szeredi
2006-03-22 20:07                               ` Trond Myklebust
2006-03-22 20:19                                 ` Miklos Szeredi

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