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Thu, 9 Dec 2021 15:30:26 +0000 (GMT) Received: from jarvis.int.hansenpartnership.com (unknown [9.211.77.2]) by b03ledav004.gho.boulder.ibm.com (Postfix) with ESMTP; Thu, 9 Dec 2021 15:30:26 +0000 (GMT) Message-ID: Subject: Re: [PATCH v5 15/16] ima: Move dentries into ima_namespace From: James Bottomley Reply-To: jejb@linux.ibm.com To: Christian Brauner , Stefan Berger Cc: linux-integrity@vger.kernel.org, zohar@linux.ibm.com, 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: Thu, 09 Dec 2021 10:30:25 -0500 In-Reply-To: <20211209143749.wk4agkynfqdzftbl@wittgenstein> References: <20211208221818.1519628-1-stefanb@linux.ibm.com> <20211208221818.1519628-16-stefanb@linux.ibm.com> <20211209143428.ip6bwry5hqtee5vy@wittgenstein> <20211209143749.wk4agkynfqdzftbl@wittgenstein> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.34.4 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: n9lfUq4FyoEkwJvR1lmrx71TH37cVJ05 X-Proofpoint-GUID: 8UFpVoAst13q_Z54f8rGfj5DDtIUiSDb 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=2021-12-09_06,2021-12-08_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 bulkscore=0 impostorscore=0 malwarescore=0 lowpriorityscore=0 suspectscore=0 mlxlogscore=999 priorityscore=1501 mlxscore=0 adultscore=0 phishscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112090082 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2021-12-09 at 15:37 +0100, Christian Brauner wrote: > On Thu, Dec 09, 2021 at 03:34:28PM +0100, Christian Brauner wrote: > > On Wed, Dec 08, 2021 at 05:18:17PM -0500, Stefan Berger wrote: > > > Move the dentries into the ima_namespace for reuse by virtualized > > > SecurityFS. Implement function freeing the dentries in order of > > > files and symlinks before directories. > > > > > > Signed-off-by: Stefan Berger > > > --- > > > > This doesn't work as implemented, I think. > > > > What I would have preferred and what I tried to explain in the > > earlier review was: > > Keep the dentry stashing global since it is only needed for > > init_ima_ns. > > Then struct ima_namespace becomes way smaller and simpler. > > If you do that then it makes sense to remove the additional dget() > > in securityfs_create_dentry() for non-init_ima_ns. > > Then you can rely on auto-cleanup in .kill_sb() or on > > ima_securityfs_init() failure and you only need to call > > ima_fs_ns_free_dentries() if ns != init_ima_ns. > > > > IIuc, it seems you're currently doing one dput() too many since > > you're calling securityfs_remove() in the error path for non- > > init_ima_ns which relies on the previous increased dget() which we > > removed. > > If you really want to move the dentry stashing into struct > ima_namespace even though it's really unnecessary then you may as > well not care about the auto-cleanup and keep that additional > ima_fs_ns_free_dentries(ns) call in .kill_sb(). But I really think > not dragging dentry stashing into struct ima_namespace is the correct > way to go about this. We, unfortunately, do have one case we can't avoid stashing for the policy file. It's this code in ima_release_policy: > #if !defined(CONFIG_IMA_WRITE_POLICY) && > !defined(CONFIG_IMA_READ_POLICY) > securityfs_remove(ns->dentry[IMAFS_DENTRY_IMA_POLICY]); > ns->dentry[IMAFS_DENTRY_IMA_POLICY] = NULL; > What it does is that in certain config options, the policy file entry gets removed from the securityfs ima directory after you write to it. James