From: Kees Cook <keescook@chromium.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Andrey Ignatov <rdna@fb.com>,
Network Development <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Roman Gushchin <guro@fb.com>, kernel-team <kernel-team@fb.com>,
Luis Chamberlain <mcgrof@kernel.org>,
Alexey Dobriyan <adobriyan@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
linux-security-module <linux-security-module@vger.kernel.org>,
Jann Horn <jannh@google.com>
Subject: Re: [PATCH v3 bpf-next 00/21] bpf: Sysctl hook
Date: Tue, 9 Apr 2019 09:50:50 -0700 [thread overview]
Message-ID: <CAGXu5jJTCjE6FiqPgnSZbp1rzNs35RV-bXXg=+Nu5bO7v1Ac0g@mail.gmail.com> (raw)
In-Reply-To: <20190406170257.qlptcrfth2rb3rxo@ast-mbp.dhcp.thefacebook.com>
On Sat, Apr 6, 2019 at 10:03 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Sat, Apr 06, 2019 at 09:43:50AM -0700, Kees Cook wrote:
> > On Fri, Apr 5, 2019 at 12:36 PM Andrey Ignatov <rdna@fb.com> wrote:
> > > BPF_CGROUP_SYSCTL hook is placed before calling to sysctl's proc_handler so
> > > that accesses (read/write) to sysctl can be controlled for specific cgroup
> > > and either allowed or denied, or traced.
> >
> > This sounds more like an LSM than BPF.
>
> not at all. the key difference is being cgroup scoped.
> essentially for different containers.
Okay, works for me. I was looking at it from the perspective of
something providing resource access control policy, which usually
falls into the LSM world.
> bpf prog is attached to this hook in a particular cgroup
> and executed for sysctls for tasks that belong to that cgroup.
So it's root limiting root-in-a-container? Nice to have some
boundaries there, for sure.
> > Can the BPF be removed (or rather,
> > what's the lifetime of such BPF?)
>
> same as all other cgroup-bpf hooks.
> Do you have a specific concern or just asking how life time of programs
> is managed?
> High level description of lifetime is here:
> https://facebookmicrosites.github.io/bpf/blog/2018/08/31/object-lifetime.html
I'm mostly curious about the access control stacking. i.e. can
in-container root add new eBPF to its own cgroup, and if so, can it
undo the restrictions already present? (I assume it can't, but figured
I'd ask...)
--
Kees Cook
next prev parent reply other threads:[~2019-04-09 16:51 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-05 19:35 [PATCH v3 bpf-next 00/21] bpf: Sysctl hook Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 01/21] bpf: Add base proto function for cgroup-bpf programs Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 02/21] bpf: Sysctl hook Andrey Ignatov
2019-04-09 16:54 ` Kees Cook
2019-04-09 20:16 ` Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 03/21] bpf: Introduce bpf_sysctl_get_name helper Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 04/21] bpf: Introduce bpf_sysctl_get_current_value helper Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 05/21] bpf: Introduce bpf_sysctl_{get,set}_new_value helpers Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 06/21] bpf: Add file_pos field to bpf_sysctl ctx Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 07/21] bpf: Sync bpf.h to tools/ Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 08/21] libbpf: Support sysctl hook Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 09/21] selftests/bpf: Test sysctl section name Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 10/21] selftests/bpf: Test BPF_CGROUP_SYSCTL Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 11/21] selftests/bpf: Test bpf_sysctl_get_name helper Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 12/21] selftests/bpf: Test sysctl_get_current_value helper Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 13/21] selftests/bpf: Test bpf_sysctl_{get,set}_new_value helpers Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 14/21] selftests/bpf: Test file_pos field in bpf_sysctl ctx Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 15/21] bpf: Introduce ARG_PTR_TO_{INT,LONG} arg types Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 16/21] bpf: Introduce bpf_strtol and bpf_strtoul helpers Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 17/21] bpf: Sync bpf.h to tools/ Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 18/21] selftests/bpf: Add sysctl and strtoX helpers to bpf_helpers.h Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 19/21] selftests/bpf: Test ARG_PTR_TO_LONG arg type Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 20/21] selftests/bpf: Test bpf_strtol and bpf_strtoul helpers Andrey Ignatov
2019-04-05 19:35 ` [PATCH v3 bpf-next 21/21] selftests/bpf: C based test for sysctl and strtoX Andrey Ignatov
2019-04-06 16:43 ` [PATCH v3 bpf-next 00/21] bpf: Sysctl hook Kees Cook
2019-04-06 17:02 ` Alexei Starovoitov
2019-04-09 16:50 ` Kees Cook [this message]
2019-04-09 23:17 ` Andrey Ignatov
2019-04-09 20:41 ` Jann Horn
2019-04-09 23:04 ` Andrey Ignatov
2019-04-09 23:22 ` Jann Horn
2019-04-09 23:34 ` Alexei Starovoitov
2019-04-12 21:27 ` Alexei Starovoitov
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