linux-kernel - [PATCH v3 0/1] Unprivileged chroot

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Message-Id: <20210311105242.874506-1-mic@digikod.net>
Date:   Thu, 11 Mar 2021 11:52:41 +0100
From:   Mickaël Salaün <mic@...ikod.net>
To:     Al Viro <viro@...iv.linux.org.uk>,
        James Morris <jmorris@...ei.org>,
        Serge Hallyn <serge@...lyn.com>
Cc:     Mickaël Salaün <mic@...ikod.net>,
        Andy Lutomirski <luto@...capital.net>,
        Casey Schaufler <casey@...aufler-ca.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Christoph Hellwig <hch@....de>,
        David Howells <dhowells@...hat.com>,
        Dominik Brodowski <linux@...inikbrodowski.net>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        John Johansen <john.johansen@...onical.com>,
        Kees Cook <keescook@...omium.org>,
        Kentaro Takeda <takedakn@...data.co.jp>,
        Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>,
        kernel-hardening@...ts.openwall.com, linux-fsdevel@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: [PATCH v3 0/1] Unprivileged chroot

Hi,

This new patch replaces the path_is_under() check with
current_chrooted() as it is done with user namespaces.  Indeed, it is
much more simple to check the current root instead of limiting access to
a subset of files.

The chroot system call is currently limited to be used by processes with
the CAP_SYS_CHROOT capability.  This protects against malicious
procesess willing to trick SUID-like binaries.  The following patch
allows unprivileged users to safely use chroot(2), which may be
complementary to the use of user namespaces.

This patch is a follow-up of a previous one sent by Andy Lutomirski some
time ago:
https://lore.kernel.org/lkml/0e2f0f54e19bff53a3739ecfddb4ffa9a6dbde4d.1327858005.git.luto@amacapital.net/

This patch can be applied on top of v5.12-rc2 .  I would really
appreciate constructive reviews.

Previous version:
https://lore.kernel.org/r/20210310181857.401675-1-mic@digikod.net

Regards,

Mickaël Salaün (1):
  fs: Allow no_new_privs tasks to call chroot(2)

 fs/open.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)


base-commit: a38fd8748464831584a19438cbb3082b5a2dab15
-- 
2.30.2