From: "Serge E. Hallyn" <serge@hallyn.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Linux Containers <containers@lists.linux-foundation.org>,
serge@hallyn.com, agruenba@redhat.com,
gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
oleg@redhat.com, paul@paul-moore.com, viro@zeniv.linux.org.uk,
avagin@openvz.org, linux-api@vger.kernel.org,
linux-fsdevel@vger.kernel.org, mtk.manpages@gmail.com,
akpm@linux-foundation.org, luto@amacapital.net,
gorcunov@openvz.org, mingo@kernel.org, keescook@chromium.org,
Kirill Tkhai <ktkhai@virtuozzo.com>
Subject: Re: [PATCH] userns,pidns: Verify the userns for new pid namespaces
Date: Sat, 29 Apr 2017 15:53:25 -0500 [thread overview]
Message-ID: <20170429205325.GB1119@mail.hallyn.com> (raw)
In-Reply-To: <87vapnrp7f.fsf_-_@xmission.com>
Quoting Eric W. Biederman (ebiederm@xmission.com):
>
> It is pointless and confusing to allow a pid namespace hierarchy and
> the user namespace hierarchy to get out of sync. The owner of a child
> pid namespace should be the owner of the parent pid namespace or
> a descendant of the owner of the parent pid namespace.
>
> Otherwise it is possible to construct scenarios where it is legal to
> do something in a parent pid namespace but in a child pid namespace.
Hi,
did you mean 'but not in a child...' above?
> It requires use of setns into a pid namespace (but not into a user
> namespace) to create such a scenario.
>
> Add the function in_userns to help in making this determination.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
> ---
>
> While review a patch from Kiril Tkhai I realized we were missing this
> sanity check....
>
> include/linux/user_namespace.h | 8 +++++++-
> kernel/pid_namespace.c | 4 ++++
> kernel/user_namespace.c | 18 ++++++++++++------
> 3 files changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> index 32354b4b4b2b..497ed50004db 100644
> --- a/include/linux/user_namespace.h
> +++ b/include/linux/user_namespace.h
> @@ -112,8 +112,9 @@ extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t,
> extern ssize_t proc_setgroups_write(struct file *, const char __user *, size_t, loff_t *);
> extern int proc_setgroups_show(struct seq_file *m, void *v);
> extern bool userns_may_setgroups(const struct user_namespace *ns);
> +extern bool in_userns(const struct user_namespace *ancestor,
> + const struct user_namespace *child);
> extern bool current_in_userns(const struct user_namespace *target_ns);
> -
> struct ns_common *ns_get_owner(struct ns_common *ns);
> #else
>
> @@ -144,6 +145,11 @@ static inline bool userns_may_setgroups(const struct user_namespace *ns)
> return true;
> }
>
> +static inline bool in_userns(const struct user_namespace *target_ns)
> +{
> + return true;
> +}
> +
> static inline bool current_in_userns(const struct user_namespace *target_ns)
> {
> return true;
> diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
> index de461aa0bf9a..749147f5a613 100644
> --- a/kernel/pid_namespace.c
> +++ b/kernel/pid_namespace.c
> @@ -101,6 +101,10 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns
> int i;
> int err;
>
> + err = -EINVAL;
> + if (!in_userns(parent_pid_ns->user_ns, user_ns))
> + goto out;
> +
> err = -ENOSPC;
> if (level > MAX_PID_NS_LEVEL)
> goto out;
> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
> index 2f735cbe05e8..7d8658fbabc8 100644
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -986,19 +986,25 @@ bool userns_may_setgroups(const struct user_namespace *ns)
> }
>
> /*
> - * Returns true if @ns is the same namespace as or a descendant of
> - * @target_ns.
> + * Returns true if @child is the same namespace or a descendant of
> + * @ancestor.
> */
> -bool current_in_userns(const struct user_namespace *target_ns)
> +bool in_userns(const struct user_namespace *ancestor,
> + const struct user_namespace *child)
> {
> - struct user_namespace *ns;
> - for (ns = current_user_ns(); ns; ns = ns->parent) {
> - if (ns == target_ns)
> + const struct user_namespace *ns;
> + for (ns = child; ns; ns = ns->parent) {
> + if (ns == ancestor)
> return true;
> }
> return false;
> }
>
> +bool current_in_userns(const struct user_namespace *target_ns)
> +{
> + return in_userns(target_ns, current_user_ns());
> +}
> +
> static inline struct user_namespace *to_user_ns(struct ns_common *ns)
> {
> return container_of(ns, struct user_namespace, ns);
> --
> 2.10.1
next prev parent reply other threads:[~2017-04-29 20:53 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-27 12:32 [PATCH v3] pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy Kirill Tkhai
[not found] ` <149329634856.21195.14196911999722279118.stgit-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2017-04-27 15:15 ` Eric W. Biederman
[not found] ` <87mvb16fv7.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-27 15:52 ` Kirill Tkhai
[not found] ` <12a73543-79ea-4bac-7e96-6ab237534af2-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-04-27 16:07 ` Eric W. Biederman
[not found] ` <877f254yx0.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-28 9:13 ` Kirill Tkhai
[not found] ` <a9941daf-861b-453c-37b8-e95389a9959b-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-04-29 19:12 ` Eric W. Biederman
[not found] ` <8737crt4dz.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-29 19:25 ` [PATCH] userns,pidns: Verify the userns for new pid namespaces Eric W. Biederman
2017-04-29 20:53 ` Serge E. Hallyn [this message]
[not found] ` <20170429205325.GB1119-7LNsyQBKDXoIagZqoN9o3w@public.gmane.org>
2017-04-30 4:33 ` Eric W. Biederman
[not found] ` <87a86yseej.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-04-30 4:42 ` Eric W. Biederman
[not found] ` <87vapnrp7f.fsf_-_-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
2017-05-02 10:03 ` Kirill Tkhai
2017-05-02 10:04 ` Kirill Tkhai
[not found] ` <fab323b8-a909-bbce-77d2-afbcd3b0452e-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-05-02 20:39 ` Eric W. Biederman
2017-05-02 9:53 ` [PATCH v3] pid_ns: Introduce ioctl to set vector of ns_last_pid's on ns hierarhy Kirill Tkhai
[not found] ` <d2b88252-d579-8deb-2c32-4118b8464b6b-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
2017-05-02 21:26 ` Eric W. Biederman
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