From: Paolo Abeni <pabeni@redhat.com>
To: Florian Westphal <fw@strlen.de>, Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jakub Sitnicki <jakub@cloudflare.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
kernel-team@cloudflare.com
Subject: Re: [RFC bpf-next 0/7] Programming socket lookup with BPF
Date: Fri, 21 Jun 2019 18:54:27 +0200 [thread overview]
Message-ID: <68be4409580e99b1487b32f36bfc52f3e3f79530.camel@redhat.com> (raw)
In-Reply-To: <20190621164131.6ghtx6b7dzivsfxk@breakpoint.cc>
Hi,
On Fri, 2019-06-21 at 18:41 +0200, Florian Westphal wrote:
> Eric Dumazet <eric.dumazet@gmail.com> wrote:
> > > AFAICS so far this would be enough:
> > >
> > > 1. remove the BUG_ON() in skb_orphan, letting it clear skb->sk instead
> > > 2. in nf_queue_entry_get_refs(), if skb->sk and no destructor:
> > > call nf_tproxy_assign_sock() so a reference gets taken.
> > > 3. change skb_steal_sock:
> > > static inline struct sock *skb_steal_sock(struct sk_buff *skb, bool *refcounted)
> > > [..]
> > > *refcounted = skb->destructor != NULL;
> > > 4. make tproxy sk assign elide the destructor assigment in case of
> > > a listening sk.
> > >
> >
> > Okay, but how do we make sure the skb->sk association does not leak from rcu section ?
>
> From netfilter pov the only escape point is nfqueue (and kfree_skb),
> so for tcp/udp it will end up in their respective rx path eventually.
> But you are right in that we need to also audit all NF_STOLEN users that
> can be invoked from PRE_ROUTING and INPUT hooks.
>
> OUTPUT/FORWARD/POSTROUTING are not relevant, in case skb enters IP forwarding,
> it will be dropped there (we have a check to toss skb with socket
> attached in forward).
>
> In recent hallway discussion Eric suggested to add a empty destructor
> stub, it would allow to do the needed annotation, i.e.
> no need to change skb_orphan(), *refcounted would be set via
> skb->destructor != noref_listen_skb_destructor check.
Perhaps I'm misreading the above, but it looks like this has some
overlapping with a past attempt:
https://marc.info/?l=linux-netdev&m=150611442802964&w=2
Cheers,
Paolo
prev parent reply other threads:[~2019-06-21 16:54 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-18 13:00 [RFC bpf-next 0/7] Programming socket lookup with BPF Jakub Sitnicki
2019-06-18 13:00 ` [RFC bpf-next 1/7] bpf: Introduce inet_lookup program type Jakub Sitnicki
2019-06-18 13:00 ` [RFC bpf-next 2/7] ipv4: Run inet_lookup bpf program on socket lookup Jakub Sitnicki
2019-06-18 13:00 ` [RFC bpf-next 3/7] ipv6: " Jakub Sitnicki
2019-06-18 13:00 ` [RFC bpf-next 4/7] bpf: Sync linux/bpf.h to tools/ Jakub Sitnicki
2019-06-18 13:00 ` [RFC bpf-next 5/7] libbpf: Add support for inet_lookup program type Jakub Sitnicki
2019-06-18 13:00 ` [RFC bpf-next 6/7] bpf: Test destination address remapping with inet_lookup Jakub Sitnicki
2019-06-18 13:00 ` [RFC bpf-next 7/7] bpf: Add verifier tests for inet_lookup context access Jakub Sitnicki
2019-06-18 13:52 ` [RFC bpf-next 0/7] Programming socket lookup with BPF Florian Westphal
2019-06-19 9:13 ` Jakub Sitnicki
2019-06-20 11:56 ` Florian Westphal
2019-06-20 22:20 ` Joe Stringer
[not found] ` <CAGn+7TUmgsA8oKw-mM6S5iR4rmNt6sWxjUgw8=qSCHb=m0ROyg@mail.gmail.com>
2019-06-21 16:50 ` Joe Stringer
2019-06-25 8:11 ` Jakub Sitnicki
2019-06-25 7:28 ` Jakub Sitnicki
2019-06-21 12:51 ` Florian Westphal
2019-06-21 14:33 ` Eric Dumazet
2019-06-21 16:41 ` Florian Westphal
2019-06-21 16:54 ` Paolo Abeni [this message]
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