From: "Mickaël Salaün" <mic@digikod.net>
To: Casey Schaufler <casey@schaufler-ca.com>,
Al Viro <viro@zeniv.linux.org.uk>,
James Morris <jmorris@namei.org>, Serge Hallyn <serge@hallyn.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
Christian Brauner <christian.brauner@ubuntu.com>,
Christoph Hellwig <hch@lst.de>,
David Howells <dhowells@redhat.com>,
Dominik Brodowski <linux@dominikbrodowski.net>,
Eric Biederman <ebiederm@xmission.com>,
John Johansen <john.johansen@canonical.com>,
Kees Cook <keescook@chromium.org>,
Kentaro Takeda <takedakn@nttdata.co.jp>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
kernel-hardening@lists.openwall.com,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH v1 0/1] Unprivileged chroot
Date: Wed, 10 Mar 2021 19:17:36 +0100 [thread overview]
Message-ID: <e0b03cf2-8e37-6a41-5132-b74566a8f269@digikod.net> (raw)
In-Reply-To: <4b9a1bb3-94f0-72af-f8f6-27f1ca2b43a2@schaufler-ca.com>
On 10/03/2021 18:22, Casey Schaufler wrote:
> On 3/10/2021 8:09 AM, Mickaël Salaün wrote:
>> Hi,
>>
>> 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).
>
> Mount namespaces have pretty well obsoleted chroot(). CAP_SYS_CHROOT is
> one of the few fine grained capabilities. We're still finding edge cases
> (e.g. ptrace) where no_new_privs is imperfect. I doesn't seem that there
> is a compelling reason to remove the privilege requirement on chroot().
What is the link between chroot and ptrace?
What is interesting with CAP_SYS_CHROOT?
>
>>
>> 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.
>>
>> Regards,
>>
>> Mickaël Salaün (1):
>> fs: Allow no_new_privs tasks to call chroot(2)
>>
>> fs/open.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
>> 1 file changed, 61 insertions(+), 3 deletions(-)
>>
>>
>> base-commit: a38fd8748464831584a19438cbb3082b5a2dab15
>
next prev parent reply other threads:[~2021-03-10 18:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 16:09 [PATCH v1 0/1] Unprivileged chroot Mickaël Salaün
2021-03-10 16:10 ` [PATCH v1 1/1] fs: Allow no_new_privs tasks to call chroot(2) Mickaël Salaün
2021-03-10 16:56 ` Eric W. Biederman
2021-03-10 18:13 ` Mickaël Salaün
2021-03-10 17:22 ` [PATCH v1 0/1] Unprivileged chroot Casey Schaufler
2021-03-10 18:17 ` Mickaël Salaün [this message]
2021-03-10 20:59 ` Casey Schaufler
2021-03-11 10:42 ` Mickaël Salaün
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