Messages in this thread | | | Date | Wed, 29 Nov 2023 23:02:01 +0800 | Subject | Re: [PATCH net] net/netfilter: bpf: avoid leakage of skb | From | "D. Wythe" <> |
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On 11/29/23 10:47 PM, Florian Westphal wrote: > D. Wythe <alibuda@linux.alibaba.com> wrote: >> And my origin intention was to allow ebpf progs to return NF_STOLEN, we are >> trying to modify some netfilter modules via ebpf, >> and some scenarios require the use of NF_STOLEN, but from your description, > NF_STOLEN can only be supported via a trusted helper, as least as far as > I understand. > > Otherwise verifier would have to guarantee that any branch that returns > NF_STOLEN has released the skb, or passed it to a function that will > release the skb in the near future.
Thank you very much for your help. I now understand the difficulty here. The verifier cannot determine whether the consume_skb() was executed or not, when the return value goes to NF_STOLEN.
We may use NF_DROP at first, it won't be make much difference for us now.
Also, do you have any plans to support this helper?
Best wishes, D. Wythe
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