Message-ID: <d8a6a6827da17825c1aa011256b96d195b1ebf13.camel@linux.ibm.com>
Subject: Re: [PATCH v5 15/16] ima: Move dentries into ima_namespace
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Stefan Berger <stefanb@linux.ibm.com>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        James Bottomley <jejb@linux.ibm.com>
Cc:     linux-integrity@vger.kernel.org, serge@hallyn.com,
        containers@lists.linux.dev, dmitry.kasatkin@gmail.com,
        ebiederm@xmission.com, krzysztof.struczynski@huawei.com,
        roberto.sassu@huawei.com, mpeters@redhat.com, lhinds@redhat.com,
        lsturman@redhat.com, puiterwi@redhat.com, jamjoom@us.ibm.com,
        linux-kernel@vger.kernel.org, paul@paul-moore.com, rgb@redhat.com,
        linux-security-module@vger.kernel.org, jmorris@namei.org
Date:   Fri, 10 Dec 2021 08:02:13 -0500
In-Reply-To: <6de8d349-74f8-7be4-3854-5c4ac72860ad@linux.ibm.com>
References: <20211208221818.1519628-1-stefanb@linux.ibm.com>
         <20211208221818.1519628-16-stefanb@linux.ibm.com>
         <20211209143428.ip6bwry5hqtee5vy@wittgenstein>
         <20211209143749.wk4agkynfqdzftbl@wittgenstein>
         <fb99af21f029b8072435e35731b919f4ec98f89d.camel@linux.ibm.com>
         <e2feaf2f6ac4bc82f328f94ca35d14cdc3ca79d1.camel@linux.ibm.com>
         <20211210114934.tacjnwryihrsx6ln@wittgenstein>
         <2587716d7d021c35e3b6ef22b6e30f44c2b3f98e.camel@linux.ibm.com>
         <6de8d349-74f8-7be4-3854-5c4ac72860ad@linux.ibm.com>
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On Fri, 2021-12-10 at 07:40 -0500, Stefan Berger wrote:
> On 12/10/21 07:09, Mimi Zohar wrote:
> > On Fri, 2021-12-10 at 12:49 +0100, Christian Brauner wrote:
> >>> There's still the problem that if you write the policy, making the file
> >>> disappear then unmount and remount securityfs it will come back.  My
> >>> guess for fixing this is that we only stash the policy file reference,
> >>> create it if NULL but then set the pointer to PTR_ERR(-EINVAL) or
> >>> something and refuse to create it for that value.
> >> Some sort of indicator that gets stashed in struct ima_ns that the file
> >> does not get recreated on consecutive mounts. That shouldn't be hard to
> >> fix.
> > The policy file disappearing is for backwards compatibility, prior to
> > being able to extend the custom policy.  For embedded usecases,
> > allowing the policy to be written exactly once might makes sense.  Do
> > we really want/need to continue to support removing the policy in
> > namespaces?
> 
> I don't have an answer but should the behavior for the same #define in 
> this case be different for host and namespaces? Or should we just 
> 'select IMA_WRITE_POLICY and IMA_READ_POLICY' when IMA_NS is selected?

The latter option sounds good.  Being able to analyze the namespace
policy is really important.

thanks,

Mimi