From: Kirill Tkhai <ktkhai-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
To: "Eric W. Biederman"
<ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>,
Linux Containers
<containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>
Cc: serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org,
agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org,
paul-r2n+y4ga6xFZroRs9YW3xA@public.gmane.org,
viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org,
avagin-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org,
luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org,
gorcunov-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org,
mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org,
keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org
Subject: Re: [PATCH] userns,pidns: Verify the userns for new pid namespaces
Date: Tue, 2 May 2017 13:03:04 +0300 [thread overview]
Message-ID: <d67c8c06-2e6b-9cc0-df81-71d3cf4bb43d@virtuozzo.com> (raw)
In-Reply-To: <87vapnrp7f.fsf_-_-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
On 29.04.2017 22:25, Eric W. Biederman wrote:
>
> 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.
>
> 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-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org>
> ---
>
> 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;
> }
We have user_namespace::level, so it's possible to stop iterations earlier
and save some cpu cycles:
for (ns = child; ns->level >= ancestor->level; ns = ns->parent)
;
return (ns == ancestor);
>
> +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);
>
next prev parent reply other threads:[~2017-05-02 10:03 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
[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 [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=d67c8c06-2e6b-9cc0-df81-71d3cf4bb43d@virtuozzo.com \
--to=ktkhai-5hdwgun5lf+gspxsjd1c4w@public.gmane.org \
--cc=agruenba-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org \
--cc=akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org \
--cc=avagin-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org \
--cc=containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org \
--cc=ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org \
--cc=gorcunov-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org \
--cc=gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org \
--cc=keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org \
--cc=linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
--cc=luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org \
--cc=mingo-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org \
--cc=mtk.manpages-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org \
--cc=oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org \
--cc=paul-r2n+y4ga6xFZroRs9YW3xA@public.gmane.org \
--cc=serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org \
--cc=viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).