Messages in this thread |  | | | Date | Sat, 24 Feb 2007 16:27:16 +0100 | | From | Patrick McHardy <> | | Subject | Re: [PATCH 18/29] netfilter: notify about NF_QUEUE vs emergency skbs |
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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.
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