linux-ext4 - Re: [PATCH v6 04/40] capability: handle idmapped mounts

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Message-ID: <d4ca369d-f953-f0ba-dd7c-d189ab1b631@namei.org>
Date:   Fri, 22 Jan 2021 13:57:11 +1100 (AEDT)
From:   James Morris <jmorris@...ei.org>
To:     Christian Brauner <christian.brauner@...ntu.com>
cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Christoph Hellwig <hch@....de>, linux-fsdevel@...r.kernel.org,
        John Johansen <john.johansen@...onical.com>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        Stephen Smalley <stephen.smalley.work@...il.com>,
        Casey Schaufler <casey@...aufler-ca.com>,
        Arnd Bergmann <arnd@...db.de>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
        Geoffrey Thomas <geofft@...reload.com>,
        Mrunal Patel <mpatel@...hat.com>,
        Josh Triplett <josh@...htriplett.org>,
        Andy Lutomirski <luto@...nel.org>,
        Theodore Tso <tytso@....edu>, Alban Crequy <alban@...volk.io>,
        Tycho Andersen <tycho@...ho.ws>,
        David Howells <dhowells@...hat.com>,
        James Bottomley <James.Bottomley@...senpartnership.com>,
        Seth Forshee <seth.forshee@...onical.com>,
        Stéphane Graber <stgraber@...ntu.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Aleksa Sarai <cyphar@...har.com>,
        Lennart Poettering <lennart@...ttering.net>,
        "Eric W. Biederman" <ebiederm@...ssion.com>, smbarber@...omium.org,
        Phil Estes <estesp@...il.com>, Serge Hallyn <serge@...lyn.com>,
        Kees Cook <keescook@...omium.org>,
        Todd Kjos <tkjos@...gle.com>, Paul Moore <paul@...l-moore.com>,
        Jonathan Corbet <corbet@....net>,
        containers@...ts.linux-foundation.org,
        linux-security-module@...r.kernel.org, linux-api@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-integrity@...r.kernel.org, selinux@...r.kernel.org
Subject: Re: [PATCH v6 04/40] capability: handle idmapped mounts

On Thu, 21 Jan 2021, Christian Brauner wrote:

> In order to determine whether a caller holds privilege over a given
> inode the capability framework exposes the two helpers
> privileged_wrt_inode_uidgid() and capable_wrt_inode_uidgid(). The former
> verifies that the inode has a mapping in the caller's user namespace and
> the latter additionally verifies that the caller has the requested
> capability in their current user namespace.
> If the inode is accessed through an idmapped mount map it into the
> mount's user namespace. Afterwards the checks are identical to
> non-idmapped inodes. If the initial user namespace is passed all
> operations are a nop so non-idmapped mounts will not see a change in
> behavior.
> 
> Link: https://lore.kernel.org/r/20210112220124.837960-11-christian.brauner@ubuntu.com
> Cc: Christoph Hellwig <hch@....de>
> Cc: David Howells <dhowells@...hat.com>
> Cc: Al Viro <viro@...iv.linux.org.uk>
> Cc: linux-fsdevel@...r.kernel.org
> Reviewed-by: Christoph Hellwig <hch@....de>
> Acked-by: Serge Hallyn <serge@...lyn.com>
> Signed-off-by: Christian Brauner <christian.brauner@...ntu.com>


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


-- 
James Morris
<jmorris@...ei.org>