From: Stanislav Fomichev <sdf@fomichev.me>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Stanislav Fomichev <sdf@google.com>,
Network Development <netdev@vger.kernel.org>,
bpf@vger.kernel.org, David Miller <davem@davemloft.net>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
simon.horman@netronome.com, Willem de Bruijn <willemb@google.com>,
Petar Penkov <peterpenkov96@gmail.com>
Subject: Re: [RFC bpf-next v2 7/9] bpf: when doing BPF_PROG_TEST_RUN for flow dissector use no-skb mode
Date: Wed, 20 Mar 2019 09:57:44 -0700 [thread overview]
Message-ID: <20190320165744.GI7431@mini-arch.hsd1.ca.comcast.net> (raw)
In-Reply-To: <CAF=yD-+=91KJEV==jE0VLT=FBTyM+j5sLfovk-HTj_2BbCC2Hw@mail.gmail.com>
On 03/19, Willem de Bruijn wrote:
> On Tue, Mar 19, 2019 at 6:21 PM Stanislav Fomichev <sdf@google.com> wrote:
> >
> > Now that we have __flow_bpf_dissect which works on raw data (by
> > constructing temporary on-stack skb), use it when doing
> > BPF_PROG_TEST_RUN for flow dissector.
> >
> > This should help us catch any possible bugs due to missing shinfo on
> > the per-cpu skb.
> >
> > Note that existing __skb_flow_bpf_dissect swallows L2 headers and returns
> > nhoff=0, we need to preserve the existing behavior.
> >
> > Signed-off-by: Stanislav Fomichev <sdf@google.com>
> > ---
> > net/bpf/test_run.c | 48 ++++++++++++++--------------------------------
> > 1 file changed, 14 insertions(+), 34 deletions(-)
> >
>
> > @@ -300,9 +277,13 @@ int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog,
> > preempt_disable();
> > time_start = ktime_get_ns();
> > for (i = 0; i < repeat; i++) {
> > - retval = bpf_flow_dissect_skb(prog, skb,
> > - &flow_keys_dissector,
> > - &flow_keys);
> > + retval = bpf_flow_dissect(prog, data, eth->h_proto, ETH_HLEN,
> > + size, &flow_keys_dissector,
> > + &flow_keys);
> > + if (flow_keys.nhoff >= ETH_HLEN)
> > + flow_keys.nhoff -= ETH_HLEN;
> > + if (flow_keys.thoff >= ETH_HLEN)
> > + flow_keys.thoff -= ETH_HLEN;
>
> why are these conditional?
Hm, I didn't want these to be negative, because bpf flow program can set
them to zero and clamp_flow_keys makes sure they are in a "sensible"
range. For this particular case, I think we need to amend
clamp_flow_keys to make sure that flow_keys.nhoff is in the range of
initial_nhoff..hlen, not 0..hlen (and then we can drop these checks).
next prev parent reply other threads:[~2019-03-20 16:57 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-19 22:19 [RFC bpf-next v2 0/9] net: flow_dissector: trigger BPF hook when called from eth_get_headlen Stanislav Fomichev
2019-03-19 22:19 ` [RFC bpf-next v2 1/9] net: introduce __init_skb{,_data,_shinfo} helpers Stanislav Fomichev
2019-03-21 3:39 ` Alexei Starovoitov
2019-03-21 4:44 ` Eric Dumazet
2019-03-21 13:58 ` Willem de Bruijn
2019-03-21 15:44 ` Stanislav Fomichev
2019-03-21 16:00 ` Alexei Starovoitov
2019-03-21 16:13 ` Willem de Bruijn
2019-03-21 20:56 ` Alexei Starovoitov
2019-03-21 21:13 ` Stanislav Fomichev
2019-03-19 22:19 ` [RFC bpf-next v2 2/9] net: introduce skb_net helper Stanislav Fomichev
2019-03-20 2:14 ` Willem de Bruijn
2019-03-20 16:49 ` Stanislav Fomichev
2019-03-19 22:19 ` [RFC bpf-next v2 3/9] net: plumb network namespace into __skb_flow_dissect Stanislav Fomichev
2019-03-19 22:19 ` [RFC bpf-next v2 4/9] net: flow_dissector: prepare for no-skb use case Stanislav Fomichev
2019-03-19 22:19 ` [RFC bpf-next v2 5/9] flow_dissector: allow access only to a subset of __sk_buff fields Stanislav Fomichev
2019-03-19 22:19 ` [RFC bpf-next v2 6/9] net: flow_dissector: handle no-skb use case Stanislav Fomichev
2019-03-19 22:19 ` [RFC bpf-next v2 7/9] bpf: when doing BPF_PROG_TEST_RUN for flow dissector use no-skb mode Stanislav Fomichev
2019-03-20 2:14 ` Willem de Bruijn
2019-03-20 16:57 ` Stanislav Fomichev [this message]
2019-03-20 18:29 ` Willem de Bruijn
2019-03-20 19:02 ` Stanislav Fomichev
2019-03-20 19:08 ` Willem de Bruijn
2019-03-20 19:19 ` Stanislav Fomichev
2019-03-20 19:23 ` Willem de Bruijn
2019-03-20 19:48 ` Stanislav Fomichev
2019-03-20 20:03 ` Willem de Bruijn
2019-03-19 22:19 ` [RFC bpf-next v2 8/9] selftests/bpf: add flow dissector bpf_skb_load_bytes helper test Stanislav Fomichev
2019-03-19 22:19 ` [RFC bpf-next v2 9/9] net: flow_dissector: pass net argument to the eth_get_headlen Stanislav Fomichev
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