From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <45E05954.8050204@trash.net> Date: Sat, 24 Feb 2007 16:27:16 +0100 From: Patrick McHardy MIME-Version: 1.0 Subject: Re: [PATCH 18/29] netfilter: notify about NF_QUEUE vs emergency skbs References: <20070221144304.512721000@taijtu.programming.kicks-ass.net> <20070221144843.299254000@taijtu.programming.kicks-ass.net> In-Reply-To: <20070221144843.299254000@taijtu.programming.kicks-ass.net> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, Trond Myklebust , Thomas Graf , David Miller List-ID: Peter Zijlstra wrote: > Emergency skbs should never touch user-space, however NF_QUEUE is fully user > configurable. Notify the user of his mistake and try to continue. > > --- linux-2.6-git.orig/net/netfilter/core.c 2007-02-14 12:09:07.000000000 +0100 > +++ linux-2.6-git/net/netfilter/core.c 2007-02-14 12:09:18.000000000 +0100 > @@ -187,6 +187,11 @@ next_hook: > kfree_skb(*pskb); > ret = -EPERM; > } else if ((verdict & NF_VERDICT_MASK) == NF_QUEUE) { > + if (unlikely((*pskb)->emergency)) { > + printk(KERN_ERR "nf_hook: NF_QUEUE encountered for " > + "emergency skb - skipping rule.\n"); > + goto next_hook; > + } If I'm not mistaken any skb on the receive side might get allocated from the reserve. I don't see how the user could avoid this except by not using queueing at all. I also didn't see a patch dropping packets allocated from the reserve that are forwarded or processed directly without getting queued to a socket, so this would allow them to bypass userspace queueing and still go through. I think the user should just exclude packets necessary for swapping from queueing manually, based on IP addresses, port numbers or something like that. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org