From: Kees Cook <keescook@chromium.org>
To: KP Singh <kpsingh@chromium.org>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>,
Casey Schaufler <casey@schaufler-ca.com>,
linux-kernel@vger.kernel.org, bpf@vger.kernel.org,
LSM List <linux-security-module@vger.kernel.org>,
Brendan Jackman <jackmanb@google.com>,
Florent Revest <revest@google.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
James Morris <jmorris@namei.org>, Paul Turner <pjt@google.com>,
Jann Horn <jannh@google.com>,
Florent Revest <revest@chromium.org>,
Brendan Jackman <jackmanb@chromium.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Paul Moore <paul@paul-moore.com>
Subject: Re: [PATCH bpf-next v5 4/7] bpf: lsm: Implement attach, detach and execution
Date: Tue, 24 Mar 2020 11:34:52 -0700 [thread overview]
Message-ID: <202003241133.16C02BE5B@keescook> (raw)
In-Reply-To: <20200324183130.GA6784@chromium.org>
On Tue, Mar 24, 2020 at 07:31:30PM +0100, KP Singh wrote:
> On 24-Mär 19:27, KP Singh wrote:
> > We do not have a specific capable check for BPF_PROG_TYPE_LSM programs
> > now. There is a general check which requires CAP_SYS_ADMIN when
> > unprivileged BPF is disabled:
> >
> > in kernel/bpf/sycall.c:
> >
> > if (sysctl_unprivileged_bpf_disabled && !capable(CAP_SYS_ADMIN))
> > return -EPERM;
> >
> > AFAIK, Most distros disable unprivileged eBPF.
> >
> > Now that I look at this, I think we might need a CAP_MAC_ADMIN check
> > though as unprivileged BPF being enabled will result in an
> > unprivileged user being able to load MAC policies.
>
> Actually we do have an extra check for loading BPF programs:
>
>
> in kernel/bpf/syscall.c:bpf_prog_load
>
> if (type != BPF_PROG_TYPE_SOCKET_FILTER &&
> type != BPF_PROG_TYPE_CGROUP_SKB &&
> !capable(CAP_SYS_ADMIN))
> return -EPERM;
>
> Do you think we still need a CAP_MAC_ADMIN check for LSM programs?
IMO, these are distinct privileges on the non-SELinux system. I think
your patch is fine as-is.
--
Kees Cook
next prev parent reply other threads:[~2020-03-24 18:34 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-23 16:44 [PATCH bpf-next v5 0/8] MAC and Audit policy using eBPF (KRSI) KP Singh
2020-03-23 16:44 ` [PATCH bpf-next v5 1/7] bpf: Introduce BPF_PROG_TYPE_LSM KP Singh
2020-03-23 19:02 ` Yonghong Song
2020-03-23 16:44 ` [PATCH bpf-next v5 2/7] security: Refactor declaration of LSM hooks KP Singh
2020-03-23 19:33 ` Kees Cook
2020-03-23 19:56 ` Andrii Nakryiko
2020-03-24 16:06 ` KP Singh
2020-03-23 16:44 ` [PATCH bpf-next v5 3/7] bpf: lsm: provide attachment points for BPF LSM programs KP Singh
2020-03-23 19:04 ` Yonghong Song
2020-03-23 19:33 ` Kees Cook
2020-03-23 19:59 ` Andrii Nakryiko
2020-03-24 10:39 ` KP Singh
2020-03-24 16:12 ` KP Singh
2020-03-24 21:26 ` Andrii Nakryiko
2020-03-24 22:39 ` KP Singh
2020-03-23 16:44 ` [PATCH bpf-next v5 4/7] bpf: lsm: Implement attach, detach and execution KP Singh
2020-03-23 19:16 ` Yonghong Song
2020-03-23 19:44 ` KP Singh
2020-03-23 20:18 ` Andrii Nakryiko
2020-03-24 19:00 ` KP Singh
2020-03-24 14:35 ` Stephen Smalley
2020-03-24 14:50 ` KP Singh
2020-03-24 14:58 ` Stephen Smalley
2020-03-24 16:25 ` Casey Schaufler
2020-03-24 17:49 ` Stephen Smalley
2020-03-24 18:01 ` Kees Cook
2020-03-24 18:06 ` KP Singh
2020-03-24 18:21 ` Stephen Smalley
2020-03-24 18:27 ` KP Singh
2020-03-24 18:31 ` KP Singh
2020-03-24 18:34 ` Kees Cook [this message]
2020-03-24 18:33 ` Kees Cook
2020-03-23 16:44 ` [PATCH bpf-next v5 5/7] bpf: lsm: Initialize the BPF LSM hooks KP Singh
2020-03-23 19:44 ` Kees Cook
2020-03-23 19:47 ` KP Singh
2020-03-23 20:21 ` Andrii Nakryiko
2020-03-23 20:47 ` Casey Schaufler
2020-03-23 21:44 ` Kees Cook
2020-03-24 1:13 ` Casey Schaufler
2020-03-24 1:52 ` KP Singh
2020-03-24 14:37 ` Stephen Smalley
2020-03-24 14:42 ` KP Singh
2020-03-24 14:51 ` Stephen Smalley
2020-03-24 14:51 ` KP Singh
2020-03-24 17:57 ` Kees Cook
2020-03-23 16:44 ` [PATCH bpf-next v5 6/7] tools/libbpf: Add support for BPF_PROG_TYPE_LSM KP Singh
2020-03-23 19:21 ` Yonghong Song
2020-03-23 20:25 ` Andrii Nakryiko
2020-03-24 1:57 ` KP Singh
2020-03-23 16:44 ` [PATCH bpf-next v5 7/7] bpf: lsm: Add selftests " KP Singh
2020-03-23 20:04 ` Yonghong Song
2020-03-24 20:04 ` KP Singh
2020-03-24 23:54 ` Andrii Nakryiko
2020-03-25 0:36 ` KP Singh
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