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Groups > linux.kernel > #1449052
| From | ebiederm@xmission.com (Eric W. Biederman) |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace |
| Date | 2016-07-24 07:20 +0200 |
| Message-ID | <rYjZv-3Nk-1@gated-at.bofh.it> (permalink) |
| References | <rUWZs-6XY-11@gated-at.bofh.it> <rV0Tn-ZV-5@gated-at.bofh.it> <rV0Tn-ZV-15@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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
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[PATCH 0/5 RFC] Add an interface to discover relationships between namespaces Andrey Vagin <avagin@openvz.org> - 2016-07-14 20:30 +0200
[PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace Andrey Vagin <avagin@openvz.org> - 2016-07-14 20:30 +0200
Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace "W. Trevor King" <wking@tremily.us> - 2016-07-14 21:10 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces Andrey Vagin <avagin@openvz.org> - 2016-07-15 00:10 +0200
[PATCH 5/5] tools/testing: add a test to check nsfs ioctl-s Andrey Vagin <avagin@openvz.org> - 2016-07-15 04:20 +0200
[PATCH 4/5] nsfs: add ioctl to get a parent namespace Andrey Vagin <avagin@openvz.org> - 2016-07-15 04:20 +0200
Re: [PATCH 4/5] nsfs: add ioctl to get a parent namespace ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 07:30 +0200
[PATCH 3/5] nsfs: add ioctl to get an owning user namespace for ns file descriptor Andrey Vagin <avagin@openvz.org> - 2016-07-15 04:20 +0200
[PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace Andrey Vagin <avagin@openvz.org> - 2016-07-15 04:20 +0200
Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 07:20 +0200
Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 16:50 +0200
Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace "W. Trevor King" <wking@tremily.us> - 2016-07-24 19:10 +0200
Re: [PATCH 2/5] kernel: add a helper to get an owning user namespace for a namespace "W. Trevor King" <wking@tremily.us> - 2016-07-24 19:00 +0200
Re: [PATCH 1/5] namespaces: move user_ns into ns_common ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 07:20 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 07:30 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-07-21 16:50 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces Andrey Vagin <avagin@openvz.org> - 2016-07-22 20:30 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-07-25 13:50 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-25 15:40 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com> - 2016-07-25 16:50 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces "Serge E. Hallyn" <serge@hallyn.com> - 2016-07-25 17:00 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-25 17:40 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-25 17:20 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces "W. Trevor King" <wking@tremily.us> - 2016-07-23 23:20 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces James Bottomley <James.Bottomley@HansenPartnership.com> - 2016-07-23 23:40 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces "W. Trevor King" <wking@tremily.us> - 2016-07-24 00:10 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 00:20 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces "W. Trevor King" <wking@tremily.us> - 2016-07-24 00:40 +0200
Re: [PATCH 0/5 RFC] Add an interface to discover relationships between namespaces ebiederm@xmission.com (Eric W. Biederman) - 2016-07-24 07:10 +0200
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