From: Christian Brauner <christian.brauner@ubuntu.com>
To: Stefan Berger <stefanb@linux.ibm.com>
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, jejb@linux.ibm.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: [PATCH v5 13/16] ima: Move some IMA policy and filesystem related variables into ima_namespace
Date: Mon, 13 Dec 2021 17:03:37 +0100 [thread overview]
Message-ID: <20211213160337.5uc7ifhysk4hdao7@wittgenstein> (raw)
In-Reply-To: <20211213155020.pvadnomqnsub5vg2@wittgenstein>
On Mon, Dec 13, 2021 at 04:50:20PM +0100, Christian Brauner wrote:
> On Mon, Dec 13, 2021 at 10:33:40AM -0500, Stefan Berger wrote:
> >
> > On 12/11/21 04:50, Christian Brauner wrote:
> > > On Fri, Dec 10, 2021 at 08:57:11AM -0500, Stefan Berger wrote:
> > > >
> > > >
> > > > there anything that would prevent us from setns()'ing to that target user
> > > > namespace so that we would now see that of a user namespace that we are not
> > > > allowed to see?
> > > If you're really worried about someone being able to access a securityfs
> > > instance whose userns doesn't match the userns the securityfs instance
> > > was mounted in there are multiple ways to fix it. The one that I tend to
> > > prefer is:
> > >
> > > From e0ff6a8dcc573763568e685dd70d1547efd68df9 Mon Sep 17 00:00:00 2001
> > > From: Christian Brauner <christian.brauner@ubuntu.com>
> > > Date: Fri, 10 Dec 2021 11:47:37 +0100
> > > Subject: !!!! HERE BE DRAGONS - COMPLETELY UNTESTED !!!!
> > >
> > > securityfs: only allow access to securityfs from within same namespace
> > >
> > > Limit opening of securityfs files to callers located in the same namespace.
> > >
> > > ---
> > > security/inode.c | 33 +++++++++++++++++++++++++++++++--
> > > 1 file changed, 31 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/security/inode.c b/security/inode.c
> > > index eaccba7017d9..9eaf757c08cb 100644
> > > --- a/security/inode.c
> > > +++ b/security/inode.c
> > > @@ -80,6 +80,35 @@ static struct file_system_type fs_type = {
> > > .fs_flags = FS_USERNS_MOUNT,
> > > };
> > > +static int securityfs_permission(struct user_namespace *mnt_userns,
> > > + struct inode *inode, int mask)
> > > +{
> > > + int err;
> > > +
> > > + err = generic_permission(&init_user_ns, inode, mask);
> > > + if (!err) {
> > > + if (inode->i_sb->s_user_ns != current_user_ns())
> > > + err = -EACCES;
> > > + }
> > > +
> > > + return err;
> > > +}
> > > +
> > > +const struct inode_operations securityfs_dir_inode_operations = {
> > > + .permission = securityfs_permission,
> > > + .lookup = simple_lookup,
> > > +};
> > > +
> > > +const struct file_operations securityfs_dir_operations = {
> > > + .permission = securityfs_permission,
> >
> >
> > This interface function on file operations doesn't exist.
>
> It's almost as if the subject line of this patch warned about its draft
> character. That was supposed for regular files.
>
> >
> > I'll use the inode_operations and also hook it to the root dentry of the
> > super_block. Then there's no need to have this check on symlinks and
> > files...
>
> Don't special case the inode_operations for the root inode!
> If a privileged process opens an fd refering to a struct file for the
s/a privileged process/a process that is located in an ancestor userns
of the securityfs instance
> root inode and leaks it to an unprivileged process by accident the
s/unprivileged process/process located in a descendant userns
> unprivileged process can open any file or directory beneath via openat()
> and friends.
next prev parent reply other threads:[~2021-12-13 16:03 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-08 22:18 [PATCH v5 00/16] ima: Namespace IMA with audit support in IMA-ns Stefan Berger
2021-12-08 22:18 ` [PATCH v5 01/16] ima: Add IMA namespace support Stefan Berger
2021-12-09 4:40 ` kernel test robot
2021-12-09 10:56 ` kernel test robot
2021-12-09 13:19 ` kernel test robot
2021-12-10 16:00 ` kernel test robot
2021-12-08 22:18 ` [PATCH v5 02/16] ima: Define ns_status for storing namespaced iint data Stefan Berger
2021-12-08 22:18 ` [PATCH v5 03/16] ima: Namespace audit status flags Stefan Berger
2021-12-08 22:18 ` [PATCH v5 04/16] ima: Move delayed work queue and variables into ima_namespace Stefan Berger
2021-12-09 13:11 ` Christian Brauner
2021-12-09 15:09 ` Stefan Berger
2021-12-08 22:18 ` [PATCH v5 05/16] ima: Move IMA's keys queue related " Stefan Berger
2021-12-08 22:18 ` [PATCH v5 06/16] ima: Move policy " Stefan Berger
2021-12-08 22:18 ` [PATCH v5 07/16] ima: Move ima_htable " Stefan Berger
2021-12-09 16:26 ` kernel test robot
2021-12-08 22:18 ` [PATCH v5 08/16] ima: Move measurement list related variables " Stefan Berger
2021-12-08 22:18 ` [PATCH v5 09/16] ima: Only accept AUDIT rules for IMA non-init_ima_ns namespaces for now Stefan Berger
2021-12-08 22:18 ` [PATCH v5 10/16] ima: Implement hierarchical processing of file accesses Stefan Berger
2021-12-08 22:18 ` [PATCH v5 11/16] securityfs: Only use simple_pin_fs/simple_release_fs for init_user_ns Stefan Berger
2021-12-08 22:18 ` [PATCH v5 12/16] securityfs: Extend securityfs with namespacing support Stefan Berger
2021-12-08 22:18 ` [PATCH v5 13/16] ima: Move some IMA policy and filesystem related variables into ima_namespace Stefan Berger
2021-12-09 19:11 ` Christian Brauner
2021-12-09 20:42 ` Stefan Berger
2021-12-10 0:57 ` Stefan Berger
2021-12-10 11:32 ` Christian Brauner
2021-12-10 13:57 ` Stefan Berger
2021-12-10 14:21 ` James Bottomley
2021-12-11 9:50 ` Christian Brauner
2021-12-11 10:45 ` Christian Brauner
2021-12-13 15:33 ` Stefan Berger
2021-12-13 15:50 ` Christian Brauner
2021-12-13 16:03 ` Christian Brauner [this message]
2021-12-13 16:25 ` Stefan Berger
2021-12-13 16:37 ` Christian Brauner
2021-12-13 16:40 ` Christian Brauner
2021-12-10 20:08 ` Stefan Berger
2021-12-11 8:46 ` Christian Brauner
2021-12-08 22:18 ` [PATCH v5 14/16] ima: Use mac_admin_ns_capable() to check corresponding capability Stefan Berger
2021-12-09 7:22 ` Denis Semakin
2021-12-09 13:23 ` James Bottomley
2021-12-09 8:09 ` Denis Semakin
2021-12-11 15:02 ` Serge E. Hallyn
2021-12-11 15:38 ` Stefan Berger
2021-12-11 16:00 ` James Bottomley
2021-12-08 22:18 ` [PATCH v5 15/16] ima: Move dentries into ima_namespace Stefan Berger
2021-12-09 14:34 ` Christian Brauner
2021-12-09 14:37 ` Christian Brauner
2021-12-09 14:41 ` Christian Brauner
2021-12-09 15:00 ` Stefan Berger
2021-12-09 15:47 ` Christian Brauner
2021-12-09 15:30 ` James Bottomley
2021-12-09 19:38 ` James Bottomley
2021-12-09 20:13 ` Stefan Berger
2021-12-10 11:49 ` Christian Brauner
2021-12-10 12:09 ` Mimi Zohar
2021-12-10 12:40 ` Stefan Berger
2021-12-10 13:02 ` Mimi Zohar
2021-12-10 14:17 ` Stefan Berger
2021-12-10 14:26 ` James Bottomley
2021-12-10 15:26 ` Mimi Zohar
2021-12-10 15:32 ` Stefan Berger
2021-12-10 15:48 ` Mimi Zohar
2021-12-10 16:40 ` Stefan Berger
2021-12-10 12:40 ` James Bottomley
2021-12-10 12:54 ` Mimi Zohar
2021-12-12 14:13 ` James Bottomley
2021-12-13 11:25 ` Christian Brauner
2021-12-08 22:18 ` [PATCH v5 16/16] ima: Setup securityfs for IMA namespace Stefan Berger
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211213160337.5uc7ifhysk4hdao7@wittgenstein \
--to=christian.brauner@ubuntu.com \
--cc=containers@lists.linux.dev \
--cc=dmitry.kasatkin@gmail.com \
--cc=ebiederm@xmission.com \
--cc=jamjoom@us.ibm.com \
--cc=jejb@linux.ibm.com \
--cc=jmorris@namei.org \
--cc=krzysztof.struczynski@huawei.com \
--cc=lhinds@redhat.com \
--cc=linux-integrity@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-security-module@vger.kernel.org \
--cc=lsturman@redhat.com \
--cc=mpeters@redhat.com \
--cc=paul@paul-moore.com \
--cc=puiterwi@redhat.com \
--cc=rgb@redhat.com \
--cc=roberto.sassu@huawei.com \
--cc=serge@hallyn.com \
--cc=stefanb@linux.ibm.com \
--cc=zohar@linux.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).