From: Song Liu <liu.song.a23@gmail.com>
To: Stanislav Fomichev <sdf@google.com>
Cc: Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
"David S . Miller" <davem@davemloft.net>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Petar Penkov <ppenkov@google.com>
Subject: Re: [PATCH bpf-next 1/2] bpf/flow_dissector: add mode to enforce global BPF flow dissector
Date: Wed, 2 Oct 2019 13:57:07 -0700 [thread overview]
Message-ID: <CAPhsuW6ywq5yySKjtdna8rXGBWdUyFgxQuy0+=2-gReXSTQ=ow@mail.gmail.com> (raw)
In-Reply-To: <20191002173357.253643-2-sdf@google.com>
On Wed, Oct 2, 2019 at 10:36 AM Stanislav Fomichev <sdf@google.com> wrote:
>
> Always use init_net flow dissector BPF program if it's attached and fall
> back to the per-net namespace one. Also, deny installing new programs if
> there is already one attached to the root namespace.
> Users can still detach their BPF programs, but can't attach any
> new ones (-EPERM).
>
> Cc: Petar Penkov <ppenkov@google.com>
> Signed-off-by: Stanislav Fomichev <sdf@google.com>
> ---
> Documentation/bpf/prog_flow_dissector.rst | 3 +++
> net/core/flow_dissector.c | 11 ++++++++++-
> 2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/bpf/prog_flow_dissector.rst b/Documentation/bpf/prog_flow_dissector.rst
> index a78bf036cadd..4d86780ab0f1 100644
> --- a/Documentation/bpf/prog_flow_dissector.rst
> +++ b/Documentation/bpf/prog_flow_dissector.rst
> @@ -142,3 +142,6 @@ BPF flow dissector doesn't support exporting all the metadata that in-kernel
> C-based implementation can export. Notable example is single VLAN (802.1Q)
> and double VLAN (802.1AD) tags. Please refer to the ``struct bpf_flow_keys``
> for a set of information that's currently can be exported from the BPF context.
> +
> +When BPF flow dissector is attached to the root network namespace (machine-wide
> +policy), users can't override it in their child network namespaces.
> diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
> index 7c09d87d3269..494e2016fe84 100644
> --- a/net/core/flow_dissector.c
> +++ b/net/core/flow_dissector.c
> @@ -115,6 +115,11 @@ int skb_flow_dissector_bpf_prog_attach(const union bpf_attr *attr,
> struct bpf_prog *attached;
> struct net *net;
>
> + if (rcu_access_pointer(init_net.flow_dissector_prog)) {
> + /* Can't override root flow dissector program */
> + return -EPERM;
Maybe -EBUSY is more accurate?
Thanks,
Song
next prev parent reply other threads:[~2019-10-02 20:57 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-02 17:33 [PATCH bpf-next 0/2] bpf/flow_dissector: add mode to enforce global BPF flow dissector Stanislav Fomichev
2019-10-02 17:33 ` [PATCH bpf-next 1/2] " Stanislav Fomichev
2019-10-02 20:57 ` Song Liu [this message]
2019-10-02 21:31 ` Stanislav Fomichev
2019-10-02 23:29 ` Andrii Nakryiko
2019-10-03 1:43 ` Stanislav Fomichev
2019-10-03 2:47 ` Andrii Nakryiko
2019-10-03 16:01 ` Stanislav Fomichev
2019-10-03 16:26 ` Andrii Nakryiko
2019-10-03 17:45 ` John Fastabend
2019-10-03 17:58 ` Stanislav Fomichev
2019-10-02 17:33 ` [PATCH bpf-next 2/2] selftests/bpf: add test for BPF flow dissector in the root namespace Stanislav Fomichev
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