linux-kernel - Re: [PATCH v6 17/17] ima: Setup securityfs for IMA namespace

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Message-ID: <2c440d28-6857-9343-2230-f0f2905fe3a7@linux.ibm.com>
Date:   Wed, 15 Dec 2021 21:41:41 -0500
From:   Stefan Berger <stefanb@...ux.ibm.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>, linux-integrity@...r.kernel.org
Cc:     serge@...lyn.com, christian.brauner@...ntu.com,
        containers@...ts.linux.dev, dmitry.kasatkin@...il.com,
        ebiederm@...ssion.com, krzysztof.struczynski@...wei.com,
        roberto.sassu@...wei.com, mpeters@...hat.com, lhinds@...hat.com,
        lsturman@...hat.com, puiterwi@...hat.com, jejb@...ux.ibm.com,
        jamjoom@...ibm.com, linux-kernel@...r.kernel.org,
        paul@...l-moore.com, rgb@...hat.com,
        linux-security-module@...r.kernel.org, jmorris@...ei.org,
        James Bottomley <James.Bottomley@...senPartnership.com>
Subject: Re: [PATCH v6 17/17] ima: Setup securityfs for IMA namespace


On 12/15/21 16:31, Mimi Zohar wrote:
> Hi Stefan, James,
>
> On Fri, 2021-12-10 at 14:47 -0500, Stefan Berger wrote:
>> Setup securityfs with symlinks, directories, and files for IMA
>> namespacing support. The same directory structure that IMA uses on the
>> host is also created for the namespacing case.
>>
>> The securityfs file and directory ownerships cannot be set when the
>> IMA namespace is initialized. Therefore, delay the setup of the file
>> system to a later point when securityfs is in securityfs_fill_super.
>>
>> This filesystem can now be mounted as follows:
>>
>> mount -t securityfs /sys/kernel/security/ /sys/kernel/security/
>>
>> The following directories, symlinks, and files are then available.
>>
>> $ ls -l sys/kernel/security/
>> total 0
>> lr--r--r--. 1 root root 0 Dec  2 00:18 ima -> integrity/ima
>> drwxr-xr-x. 3 root root 0 Dec  2 00:18 integrity
> The ima symlink was introduced for backwards compatibilty.  Refer to
> commit 0c343af8065b ("integrity: Add an integrity directory in
> securityfs").  The symlink shouldn't need to be supported in IMA
> namespace.

That's backwards compatibility for applications and scripts. If we want 
to have these running unmodified inside IMA namespaces I think it's 
better to keep the symbolic link and not treat the IMA namespaces any 
different than the host.

    Stefan

>
> thanks,
>
> Mimi
>
>> $ ls -l sys/kernel/security/ima/
>> total 0
>> -r--r-----. 1 root root 0 Dec  2 00:18 ascii_runtime_measurements
>> -r--r-----. 1 root root 0 Dec  2 00:18 binary_runtime_measurements
>> -rw-------. 1 root root 0 Dec  2 00:18 policy
>> -r--r-----. 1 root root 0 Dec  2 00:18 runtime_measurements_count
>> -r--r-----. 1 root root 0 Dec  2 00:18 violations
>>
>> Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
>> Signed-off-by: James Bottomley <James.Bottomley@...senPartnership.com>