Re: [PATCH v12 0/3] Add trusted_for(2) (was O_MAYEXEC)

From: "Mickaël Salaün" <mic@digikod.net>
To: Mimi Zohar <zohar@linux.ibm.com>, Kees Cook <keescook@chromium.org>
Cc: bauen1 <j2468h@googlemail.com>,
	akpm@linux-foundation.org, arnd@arndb.de, casey@schaufler-ca.com,
	christian.brauner@ubuntu.com, christian@python.org,
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Subject: Re: [PATCH v12 0/3] Add trusted_for(2) (was O_MAYEXEC)
Date: Thu, 7 Oct 2021 21:00:33 +0200	[thread overview]
Message-ID: <a2e63238-d4d9-ce38-bdea-93976e691a78@digikod.net> (raw)
In-Reply-To: <7ee6ba1200b854fc6012b0cec49849f7c0789f42.camel@linux.ibm.com>

On 07/10/2021 20:37, Mimi Zohar wrote:
> On Thu, 2021-10-07 at 20:29 +0200, Mickaël Salaün wrote:
>> On 07/10/2021 00:03, Kees Cook wrote:
>>> On Fri, Apr 09, 2021 at 07:15:42PM +0200, Mickaël Salaün wrote:
>>>> There was no new reviews, probably because the FS maintainers were busy,
>>>> and I was focused on Landlock (which is now in -next), but I plan to
>>>> send a new patch series for trusted_for(2) soon.
>>>
>>> Hi!
>>>
>>> Did this ever happen? It looks like it's in good shape, and I think it's
>>> a nice building block for userspace to have. Are you able to rebase and
>>> re-send this?
>>
>> I just sent it:
>> https://lore.kernel.org/all/20211007182321.872075-1-mic@digikod.net/
>>
>> Some Signed-off-by would be appreciated. :)
>>
> 
>>From the cover letter, 
> 
> It is important to note that this can only enable to extend access
> control managed by the kernel.  Hence it enables current access control
> mechanism to be extended and become a superset of what they can
> currently control.  Indeed, the security policy could also be delegated
> to an LSM, either a MAC system or an integrity system.  For instance,
> this is required to close a major IMA measurement/appraisal interpreter
> integrity gap by bringing the ability to check the use of scripts [1].
> Other uses are expected, such as for magic-links [2], SGX integration
> [3], bpffs [4].
> 
>>From a quick review of the code, I don't see a new security hook being
> defined to cover these use cases.

Indeed, there is no new hook because it would require to implement it
with a current LSM. This first step is a standalone implementation that
is useful as-is but open the way to add a new LSM hook in this new
syscall. That would be a second step for any LSM developer to implement
if interested.

> 
> thanks,
> 
> Mimi
> 
>>>
>>> I've tended to aim these things at akpm if Al gets busy. (And since
>>> you've had past review from Al, that should be hopefully sufficient.)
>>>
>>> Thanks for chasing this!
>>>
>>> -Kees
>>>
> 
> 