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Subject: Re: [PATCH RFC] perf_event: Add support for LSM and SELinux checks
To:     Joel Fernandes <joel@joelfernandes.org>
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>, casey@schaufler-ca.com
References: <20191009203657.6070-1-joel@joelfernandes.org>
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From:   Casey Schaufler <casey@schaufler-ca.com>
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Message-ID: <ea32212d-bd45-c363-841a-f4397aafd323@schaufler-ca.com>
Date:   Wed, 9 Oct 2019 17:53:41 -0700
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On 10/9/2019 5:40 PM, Joel Fernandes wrote:
> 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 on=
ly=20
>>> 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).

No, I meant allocated in security.c. Look at how file blobs are allocated=
=2E

>  The blob contains a SID which as far
> as I know, is specific to SELinux. Do you have an in-tree example of th=
is?
>
> Further, this is also exactly it is done for BPF objects which I used a=
s a
> reference.

There's no real harm in doing it that way, just that it is a change that
I'll have to make at some point in the future* and it would be really nic=
e
if I didn't have to.

> thanks,
>
>  - Joel

-----
* When? After I get the current AppArmor/SELinux stacking enabling in
  and can get to the Smack backlong, which includes BPF and perf_events.
=C2=A0