Received-SPF: pass (google.com: domain of linux-ext4-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 22 Jan 2021 15:14:30 +1100 (AEDT)
From:   James Morris <jmorris@namei.org>
To:     Christian Brauner <christian.brauner@ubuntu.com>
cc:     Alexander Viro <viro@zeniv.linux.org.uk>,
        Christoph Hellwig <hch@lst.de>, linux-fsdevel@vger.kernel.org,
        John Johansen <john.johansen@canonical.com>,
        Mimi Zohar <zohar@linux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        Stephen Smalley <stephen.smalley.work@gmail.com>,
        Casey Schaufler <casey@schaufler-ca.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>,
        Geoffrey Thomas <geofft@ldpreload.com>,
        Mrunal Patel <mpatel@redhat.com>,
        Josh Triplett <josh@joshtriplett.org>,
        Andy Lutomirski <luto@kernel.org>,
        Theodore Tso <tytso@mit.edu>, Alban Crequy <alban@kinvolk.io>,
        Tycho Andersen <tycho@tycho.ws>,
        David Howells <dhowells@redhat.com>,
        James Bottomley <James.Bottomley@hansenpartnership.com>,
        Seth Forshee <seth.forshee@canonical.com>,
        =?ISO-8859-15?Q?St=E9phane_Graber?= <stgraber@ubuntu.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Aleksa Sarai <cyphar@cyphar.com>,
        Lennart Poettering <lennart@poettering.net>,
        "Eric W. Biederman" <ebiederm@xmission.com>, smbarber@chromium.org,
        Phil Estes <estesp@gmail.com>, Serge Hallyn <serge@hallyn.com>,
        Kees Cook <keescook@chromium.org>,
        Todd Kjos <tkjos@google.com>, Paul Moore <paul@paul-moore.com>,
        Jonathan Corbet <corbet@lwn.net>,
        containers@lists.linux-foundation.org,
        linux-security-module@vger.kernel.org, linux-api@vger.kernel.org,
        linux-ext4@vger.kernel.org, linux-xfs@vger.kernel.org,
        linux-integrity@vger.kernel.org, selinux@vger.kernel.org
Subject: Re: [PATCH v6 16/40] open: handle idmapped mounts
In-Reply-To: <20210121131959.646623-17-christian.brauner@ubuntu.com>
Message-ID: <f99675af-c1-8a1a-34ef-1f701b5e9ec@namei.org>
References: <20210121131959.646623-1-christian.brauner@ubuntu.com> <20210121131959.646623-17-christian.brauner@ubuntu.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Precedence: bulk

On Thu, 21 Jan 2021, Christian Brauner wrote:

> For core file operations such as changing directories or chrooting,
> determining file access, changing mode or ownership the vfs will verify
> that the caller is privileged over the inode. Extend the various helpers
> to handle idmapped mounts. If the inode is accessed through an idmapped
> mount map it into the mount's user namespace. Afterwards the permissions
> checks are identical to non-idmapped mounts. When changing file
> ownership we need to map the uid and gid from the mount's user
> namespace. If the initial user namespace is passed nothing changes so
> non-idmapped mounts will see identical behavior as before.
> 
> Link: https://lore.kernel.org/r/20210112220124.837960-24-christian.brauner@ubuntu.com
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: David Howells <dhowells@redhat.com>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: linux-fsdevel@vger.kernel.org
> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>


Reviewed-by: James Morris <jamorris@linux.microsoft.com>


-- 
James Morris
<jmorris@namei.org>