From: Stanislav Fomichev <sdf@google.com>
To: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>,
Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Alexei Starovoitov <ast@kernel.org>
Subject: Re: [PATCH bpf-next v4 1/4] bpf: add BPF_CGROUP_INET_SOCK_RELEASE hook
Date: Tue, 7 Jul 2020 16:43:00 -0700 [thread overview]
Message-ID: <CAKH8qBujza3yn0+YXTV6zg7csWLUaA7RxEiompE5yz4QJsULoA@mail.gmail.com> (raw)
In-Reply-To: <073ac0af-5de7-0a61-4e11-e4ca292f6456@iogearbox.net>
On Tue, Jul 7, 2020 at 2:42 PM Daniel Borkmann <daniel@iogearbox.net> wrote:
>
> On 7/7/20 1:42 AM, Andrii Nakryiko wrote:
> > On Mon, Jul 6, 2020 at 4:02 PM Stanislav Fomichev <sdf@google.com> wrote:
> >>
> >> Implement BPF_CGROUP_INET_SOCK_RELEASE hook that triggers
> >> on inet socket release. It triggers only for userspace
> >> sockets, the same semantics as existing BPF_CGROUP_INET_SOCK_CREATE.
> >>
> >> The only questionable part here is the sock->sk check
> >> in the inet_release. Looking at the places where we
> >> do 'sock->sk = NULL', I don't understand how it can race
> >> with inet_release and why the check is there (it's been
> >> there since the initial git import). Otherwise, the
> >> change itself is pretty simple, we add a BPF hook
> >> to the inet_release and avoid calling it for kernel
> >> sockets.
> >>
> >> Signed-off-by: Stanislav Fomichev <sdf@google.com>
> >> ---
> >> include/linux/bpf-cgroup.h | 4 ++++
> >> include/uapi/linux/bpf.h | 1 +
> >> kernel/bpf/syscall.c | 3 +++
> >> net/core/filter.c | 1 +
> >> net/ipv4/af_inet.c | 3 +++
> >> 5 files changed, 12 insertions(+)
> >>
> >
> > Looks good overall, but I have no idea about sock->sk NULL case.
>
> +1, looks good & very useful hook. For the sock->sk NULL case here's a related
> discussion on why it's needed [0].
Thanks for the pointer! I'll resend a v5 with s/sock/sock_create/ you
mentioned and will clean up the commit description a bit.
next prev parent reply other threads:[~2020-07-07 23:43 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-06 23:01 [PATCH bpf-next v4 0/4] bpf: add BPF_CGROUP_INET_SOCK_RELEASE hook Stanislav Fomichev
2020-07-06 23:01 ` [PATCH bpf-next v4 1/4] " Stanislav Fomichev
2020-07-06 23:42 ` Andrii Nakryiko
2020-07-07 21:41 ` Daniel Borkmann
2020-07-07 23:43 ` Stanislav Fomichev [this message]
2020-07-07 23:56 ` Daniel Borkmann
2020-07-07 23:59 ` Stanislav Fomichev
2020-07-06 23:01 ` [PATCH bpf-next v4 2/4] libbpf: add support for BPF_CGROUP_INET_SOCK_RELEASE Stanislav Fomichev
2020-07-06 23:01 ` [PATCH bpf-next v4 3/4] bpftool: " Stanislav Fomichev
2020-07-06 23:01 ` [PATCH bpf-next v4 4/4] selftests/bpf: test BPF_CGROUP_INET_SOCK_RELEASE Stanislav Fomichev
2020-07-06 23:39 ` Andrii Nakryiko
2020-07-07 21:44 ` Daniel Borkmann
2020-07-07 21:58 ` Andrii Nakryiko
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