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Date:   Wed, 9 Oct 2019 20:40:23 -0400
From:   Joel Fernandes <joel@joelfernandes.org>
To:     Casey Schaufler <casey@schaufler-ca.com>
Cc:     James Morris <jmorris@namei.org>, linux-kernel@vger.kernel.org,
        Peter Zijlstra <peterz@infradead.org>, rostedt@goodmis.org,
        primiano@google.com, rsavitski@google.com, jeffv@google.com,
        kernel-team@android.com, Alexei Starovoitov <ast@kernel.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        bpf@vger.kernel.org, Daniel Borkmann <daniel@iogearbox.net>,
        Ingo Molnar <mingo@redhat.com>, Jiri Olsa <jolsa@redhat.com>,
        Kees Cook <keescook@chromium.org>,
        linux-security-module@vger.kernel.org,
        Matthew Garrett <matthewgarrett@google.com>,
        Namhyung Kim <namhyung@kernel.org>, selinux@vger.kernel.org,
        Song Liu <songliubraving@fb.com>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>,
        Yonghong Song <yhs@fb.com>
Subject: Re: [PATCH RFC] perf_event: Add support for LSM and SELinux checks
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On Wed, Oct 09, 2019 at 03:41:56PM -0700, Casey Schaufler wrote:
> On 10/9/2019 3:14 PM, James Morris wrote:
> > On Wed, 9 Oct 2019, Casey Schaufler wrote:
> >
> >> Please consider making the perf_alloc security blob maintained
> >> by the infrastructure rather than the individual modules. This
> >> will save it having to be changed later.
> > Is anyone planning on using this with full stacking?
> >
> > If not, we don't need the extra code & complexity. Stacking should only 
> > cover what's concretely required by in-tree users.
> 
> I don't believe it's any simpler for SELinux to do the allocation
> than for the infrastructure to do it. I don't see anyone's head
> exploding over the existing infrastructure allocation of blobs.
> We're likely to want it at some point, so why not avoid the hassle
> and delay by doing it the "new" way up front?
> 

I don't see how it can be maintained by the users (assuming you meant
infrastructure as perf_event subsystem). The blob contains a SID which as far
as I know, is specific to SELinux. Do you have an in-tree example of this?

Further, this is also exactly it is done for BPF objects which I used as a
reference.

thanks,

 - Joel