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Date:   Wed, 29 Nov 2023 15:47:36 +0100
From:   Florian Westphal <fw@strlen.de>
To:     "D. Wythe" <alibuda@linux.alibaba.com>
Cc:     Florian Westphal <fw@strlen.de>, pablo@netfilter.org,
        kadlec@netfilter.org, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
        coreteam@netfilter.org, netfilter-devel@vger.kernel.org,
        davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        pabeni@redhat.com, ast@kernel.org
Subject: Re: [PATCH net] net/netfilter: bpf: avoid leakage of skb
Message-ID: <20231129144736.GB24754@breakpoint.cc>
References: <1701252962-63418-1-git-send-email-alibuda@linux.alibaba.com>
 <20231129131846.GC27744@breakpoint.cc>
 <aa83bf32-789f-fec2-ea42-74b0ae05426e@linux.alibaba.com>
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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.