From: James Bottomley <jejb@linux.ibm.com>
To: Stefan Berger <stefanb@linux.ibm.com>, linux-integrity@vger.kernel.org
Cc: zohar@linux.ibm.com, serge@hallyn.com,
christian.brauner@ubuntu.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
Subject: Re: [RFC 20/20] ima: Setup securityfs_ns for IMA namespace
Date: Wed, 01 Dec 2021 12:56:27 -0500 [thread overview]
Message-ID: <6599ac61289e3316bff53602a0bc5970133251aa.camel@linux.ibm.com> (raw)
In-Reply-To: <20211130160654.1418231-21-stefanb@linux.ibm.com>
On Tue, 2021-11-30 at 11:06 -0500, Stefan Berger wrote:
[...]
> +
> +/*
> + * Fix the ownership (uid/gid) of the dentry's that couldn't be set
> at the
> + * time of their creation because the user namespace wasn't
> configured, yet.
> + */
> +static void ima_fs_ns_fixup_uid_gid(struct ima_namespace *ns)
> +{
> + struct inode *inode;
> + size_t i;
> +
> + if (ns->file_ownership_fixes_done ||
> + ns->user_ns->uid_map.nr_extents == 0)
> + return;
> +
> + ns->file_ownership_fixes_done = true;
> + for (i = 0; i < IMAFS_DENTRY_LAST; i++) {
> + if (!ns->dentry[i])
> + continue;
> + inode = ns->dentry[i]->d_inode;
> + inode->i_uid = make_kuid(ns->user_ns, 0);
> + inode->i_gid = make_kgid(ns->user_ns, 0);
> + }
> +}
> +
> +/* Fix the permissions when a file is opened */
> +int ima_fs_ns_permission(struct user_namespace *mnt_userns, struct
> inode *inode,
> + int mask)
> +{
> + ima_fs_ns_fixup_uid_gid(get_current_ns());
> + return generic_permission(mnt_userns, inode, mask);
> +}
> +
> +const struct inode_operations ima_fs_ns_inode_operations = {
> + .lookup = simple_lookup,
> + .permission = ima_fs_ns_permission,
> +};
> +
In theory this uid/gid shifting should have already been done for you
and all of the above code should be unnecessary. What is supposed to
happen is that the mount of securityfs_ns in the new user namespace
should pick up a superblock s_user_ns for that new user namespace. Now
inode_alloc() uses i_uid_write(inode, 0) which maps back through the
s_user_ns to obtain the owner of the user namespace.
What can happen is that if you do the inode allocation before (or even
without) writing to the uid_map file, it maps back through an empty map
and ends up with -1 for i_uid ... is this what you're seeing?
James
next prev parent reply other threads:[~2021-12-01 17:57 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-30 16:06 [RFC 00/20] ima: Namespace IMA with audit support in IMA-ns Stefan Berger
2021-11-30 16:06 ` [RFC 01/20] ima: Add IMA namespace support Stefan Berger
2021-11-30 16:06 ` [RFC 02/20] ima: Define ns_status for storing namespaced iint data Stefan Berger
2021-11-30 16:06 ` [RFC 03/20] ima: Namespace audit status flags Stefan Berger
2021-11-30 16:06 ` [RFC 04/20] ima: Move delayed work queue and variables into ima_namespace Stefan Berger
2021-11-30 16:06 ` [RFC 05/20] ima: Move IMA's keys queue related " Stefan Berger
2021-11-30 16:06 ` [RFC 06/20] ima: Move policy " Stefan Berger
2021-11-30 16:06 ` [RFC 07/20] ima: Move ima_htable " Stefan Berger
2021-11-30 16:06 ` [RFC 08/20] ima: Move measurement list related variables " Stefan Berger
2021-12-02 12:46 ` James Bottomley
2021-12-02 13:41 ` Stefan Berger
2021-12-02 16:29 ` James Bottomley
2021-12-02 16:45 ` Stefan Berger
2021-12-02 17:44 ` James Bottomley
2021-12-02 18:03 ` Stefan Berger
2021-12-02 20:03 ` James Bottomley
2021-11-30 16:06 ` [RFC 09/20] ima: Only accept AUDIT rules for IMA non-init_ima_ns namespaces for now Stefan Berger
2021-11-30 16:06 ` [RFC 10/20] ima: Implement hierarchical processing of file accesses Stefan Berger
2021-11-30 16:06 ` [RFC 11/20] securityfs: Prefix global variables with securityfs_ Stefan Berger
2021-11-30 16:06 ` [RFC 12/20] securityfs: Pass static variables as parameters from top level functions Stefan Berger
2021-11-30 16:06 ` [RFC 13/20] securityfs: Build securityfs_ns for namespacing support Stefan Berger
2021-12-02 13:35 ` Christian Brauner
2021-12-02 13:47 ` Stefan Berger
2021-11-30 16:06 ` [RFC 14/20] ima: Move some IMA policy and filesystem related variables into ima_namespace Stefan Berger
2021-11-30 16:06 ` [RFC 15/20] capabilities: Introduce CAP_INTEGRITY_ADMIN Stefan Berger
2021-11-30 17:27 ` Casey Schaufler
2021-11-30 17:41 ` Stefan Berger
2021-11-30 17:50 ` Casey Schaufler
2021-11-30 16:06 ` [RFC 16/20] ima: Use ns_capable() for namespace policy access Stefan Berger
2021-11-30 16:06 ` [RFC 17/20] ima: Use integrity_admin_ns_capable() to check corresponding capability Stefan Berger
2021-12-01 16:58 ` James Bottomley
2021-12-01 17:35 ` Stefan Berger
2021-12-01 19:29 ` James Bottomley
2021-12-02 7:16 ` Denis Semakin
2021-12-02 12:33 ` James Bottomley
2021-12-02 17:54 ` Stefan Berger
2021-12-02 12:59 ` Christian Brauner
2021-12-02 13:01 ` Christian Brauner
2021-12-02 15:58 ` Casey Schaufler
2021-11-30 16:06 ` [RFC 18/20] userns: Introduce a refcount variable for calling early teardown function Stefan Berger
2021-11-30 16:06 ` [RFC 19/20] ima/userns: Define early teardown function for IMA namespace Stefan Berger
2021-11-30 16:06 ` [RFC 20/20] ima: Setup securityfs_ns " Stefan Berger
2021-12-01 17:56 ` James Bottomley [this message]
2021-12-01 18:11 ` Stefan Berger
2021-12-01 19:21 ` James Bottomley
2021-12-01 20:25 ` Stefan Berger
2021-12-01 21:11 ` James Bottomley
2021-12-01 21:34 ` Stefan Berger
2021-12-01 22:01 ` James Bottomley
2021-12-01 22:09 ` Stefan Berger
2021-12-01 22:19 ` James Bottomley
2021-12-02 0:02 ` Stefan Berger
2021-12-02 13:18 ` Christian Brauner
2021-12-02 13:52 ` Stefan Berger
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