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Fri, 10 Dec 2021 14:17:15 +0000 (GMT) Received: from [9.47.158.152] (unknown [9.47.158.152]) by b03ledav006.gho.boulder.ibm.com (Postfix) with ESMTP; Fri, 10 Dec 2021 14:17:14 +0000 (GMT) Message-ID: <66b377f6-40b4-77da-c02b-2650fa72d0b4@linux.ibm.com> Date: Fri, 10 Dec 2021 09:17:14 -0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH v5 15/16] ima: Move dentries into ima_namespace Content-Language: en-US To: Mimi Zohar , Christian Brauner , James Bottomley 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 References: <20211208221818.1519628-1-stefanb@linux.ibm.com> <20211208221818.1519628-16-stefanb@linux.ibm.com> <20211209143428.ip6bwry5hqtee5vy@wittgenstein> <20211209143749.wk4agkynfqdzftbl@wittgenstein> <20211210114934.tacjnwryihrsx6ln@wittgenstein> <2587716d7d021c35e3b6ef22b6e30f44c2b3f98e.camel@linux.ibm.com> <6de8d349-74f8-7be4-3854-5c4ac72860ad@linux.ibm.com> From: Stefan Berger In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: IOjL262sWXkGHJkCKlpV3zdb1tGlIk7w X-Proofpoint-ORIG-GUID: V1Swxl0fmE7wzCmpTkIlKsqbcT3lFTSm X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2021-12-10_05,2021-12-10_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 lowpriorityscore=0 priorityscore=1501 phishscore=0 spamscore=0 bulkscore=0 adultscore=0 mlxlogscore=999 mlxscore=0 impostorscore=0 malwarescore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112100081 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/10/21 08:02, Mimi Zohar wrote: > 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. Ok, I will adjust the Kconfig for this then. This then warrants the question whether to move the dentry into the ima_namespace. The current code looks like this. #if !defined(CONFIG_IMA_WRITE_POLICY) && !defined(CONFIG_IMA_READ_POLICY)         securityfs_remove(ns->policy_dentry);         ns->policy_dentry = NULL;         ns->policy_dentry_removed = true; #elif defined(CONFIG_IMA_WRITE_POLICY) With IMA_NS selecting IMA_WRITE_POLICY and IMA_READ_POLICY the above wouldn't be necessary anymore but I find it 'cleaner' to still have the dentry isolated rather than it being a global static as it was before... > > thanks, > > Mimi >