From: ebiederm@xmission.com (Eric W. Biederman)
To: Andrey Vagin <avagin@openvz.org>
Cc: linux-kernel@vger.kernel.org,
James Bottomley <James.Bottomley@HansenPartnership.com>,
Serge Hallyn <serge.hallyn@canonical.com>,
linux-api@vger.kernel.org, containers@lists.linux-foundation.org,
Alexander Viro <viro@zeniv.linux.org.uk>,
criu@openvz.org, linux-fsdevel@vger.kernel.org,
"Michael Kerrisk \(man-pages\)" <mtk.manpages@gmail.com>
Subject: Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace
Date: Sun, 24 Jul 2016 00:03:49 -0500 [thread overview]
Message-ID: <878twrmxu2.fsf@x220.int.ebiederm.org> (raw)
In-Reply-To: <1468548742-32136-2-git-send-email-avagin@openvz.org> (Andrey Vagin's message of "Thu, 14 Jul 2016 19:12:19 -0700")
Andrey Vagin <avagin@openvz.org> writes:
> Return -EPERM if an owning user namespace is outside of a process
> current user namespace.
>
> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
> index a5bc78c..6382e5e 100644
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -994,6 +994,30 @@ static int userns_install(struct nsproxy *nsproxy, struct ns_common *ns)
> return commit_creds(cred);
> }
>
> +struct ns_common *ns_get_owner(struct ns_common *ns)
> +{
> + const struct cred *cred = current_cred();
> + struct user_namespace *user_ns, *p;
> +
> + user_ns = p = ns->user_ns;
> + if (user_ns == NULL) { /* ns is init_user_ns */
> + /* Unprivileged user should not know that it's init_user_ns. */
> + if (capable(CAP_SYS_ADMIN))
> + return ERR_PTR(-ENOENT);
> + return ERR_PTR(-EPERM);
> + }
This permission check is not what I meant to request. This does not
handle nested user namespaces.
> + for (;;) {
> + if (p == cred->user_ns)
> + break;
> + if (p == &init_user_ns)
> + return ERR_PTR(-EPERM);
> + p = p->parent;
> + }
> +
The permission check really needs to be down here. And be:
if (!ns_capable(user_ns, CAP_SYS_ADMIN))
return ERR_PTR(-EPERM).
That cleanly and easily handles more than a depth of a single user
namespace.
> + return &get_user_ns(user_ns)->ns;
> +}
> +
> const struct proc_ns_operations userns_operations = {
> .name = "user",
> .type = CLONE_NEWUSER,
Eric
next prev parent reply other threads:[~2016-07-24 5:16 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-14 18:20 [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces Andrey Vagin
2016-07-14 18:20 ` [PATCH 1/5] namespaces: move user_ns into ns_common Andrey Vagin
2016-07-15 12:21 ` kbuild test robot
2016-07-14 18:20 ` [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace Andrey Vagin
2016-07-14 19:07 ` W. Trevor King
2016-07-14 18:20 ` [PATCH 3/5] nsfs: add ioctl to get an owning user namespace for ns file descriptor Andrey Vagin
2016-07-14 18:48 ` W. Trevor King
2016-07-14 18:20 ` [PATCH 4/5] nsfs: add ioctl to get a parent namespace Andrey Vagin
2016-07-14 18:20 ` [PATCH 5/5] tools/testing: add a test to check nsfs ioctl-s Andrey Vagin
2016-07-14 22:02 ` [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces Andrey Vagin
2016-07-15 2:12 ` [PATCH 1/5] namespaces: move user_ns into ns_common Andrey Vagin
2016-07-15 2:12 ` [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace Andrey Vagin
2016-07-24 5:03 ` Eric W. Biederman [this message]
2016-07-24 6:37 ` Andrew Vagin
2016-07-24 14:30 ` Eric W. Biederman
2016-07-24 17:05 ` W. Trevor King
2016-07-24 16:54 ` W. Trevor King
2016-07-15 2:12 ` [PATCH 3/5] nsfs: add ioctl to get an owning user namespace for ns file descriptor Andrey Vagin
2016-07-15 2:12 ` [PATCH 4/5] nsfs: add ioctl to get a parent namespace Andrey Vagin
2016-07-24 5:07 ` Eric W. Biederman
2016-07-15 2:12 ` [PATCH 5/5] tools/testing: add a test to check nsfs ioctl-s Andrey Vagin
2016-07-16 8:21 ` [PATCH 1/5] namespaces: move user_ns into ns_common kbuild test robot
2016-07-23 23:07 ` kbuild test robot
2016-07-24 5:00 ` Eric W. Biederman
2016-07-24 5:54 ` Andrew Vagin
[not found] ` <87k2gbmy02.fsf-JOvCrm2gF+uungPnsOpG7nhyD016LWXt@public.gmane.org>
2016-07-24 5:54 ` Andrew Vagin
2016-07-24 5:54 ` Andrew Vagin
2016-07-24 5:54 ` Andrew Vagin
2016-07-24 5:10 ` [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces Eric W. Biederman
2016-07-26 2:07 ` Andrew Vagin
2016-07-21 14:41 ` Michael Kerrisk (man-pages)
2016-07-21 21:06 ` Andrew Vagin
[not found] ` <20160721210650.GA10989-1ViLX0X+lBJGNQ1M2rI3KwRV3xvJKrda@public.gmane.org>
2016-07-22 6:48 ` Michael Kerrisk (man-pages)
2016-07-22 18:25 ` Andrey Vagin
2016-07-25 11:47 ` Michael Kerrisk (man-pages)
2016-07-25 13:18 ` Eric W. Biederman
2016-07-25 14:46 ` Michael Kerrisk (man-pages)
2016-07-25 14:54 ` Serge E. Hallyn
2016-07-25 15:17 ` Eric W. Biederman
2016-07-25 14:59 ` Eric W. Biederman
2016-07-26 2:54 ` Andrew Vagin
2016-07-26 8:03 ` Michael Kerrisk (man-pages)
2016-07-26 18:25 ` Andrew Vagin
2016-07-26 18:32 ` W. Trevor King
2016-07-26 19:11 ` Andrew Vagin
2016-07-26 19:17 ` Michael Kerrisk (man-pages)
2016-07-26 20:39 ` Andrew Vagin
2016-07-28 10:45 ` Michael Kerrisk (man-pages)
2016-07-28 12:56 ` Eric W. Biederman
2016-07-28 19:00 ` Michael Kerrisk (man-pages)
2016-07-29 18:05 ` Eric W. Biederman
2016-07-31 21:31 ` Michael Kerrisk (man-pages)
2016-08-01 23:01 ` Andrew Vagin
2016-07-26 19:38 ` Eric W. Biederman
2016-07-23 21:14 ` W. Trevor King
2016-07-23 21:38 ` James Bottomley
2016-07-23 21:58 ` W. Trevor King
2016-07-23 21:56 ` Eric W. Biederman
2016-07-23 22:34 ` W. Trevor King
2016-07-24 4:51 ` Eric W. Biederman
2016-08-01 18:20 ` Alban Crequy
2016-08-01 23:32 ` Andrew Vagin
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