From: "Andrew G. Morgan" <morgan@kernel.org>
To: "Serge E. Hallyn" <serge@hallyn.com>
Cc: David Howells <dhowells@redhat.com>,
linux-kernel@vger.kernel.org, ebiederm@xmission.com,
akpm@linux-foundation.org, oleg@redhat.com, richard@nod.at,
mikevs@xs4all.net, segoon@openwall.com, gregkh@suse.de,
eparis@redhat.com, "Serge E. Hallyn" <serge.hallyn@canonical.com>
Subject: Re: [PATCH 05/10] user namespace: clamp down users of cap_raised
Date: Mon, 24 Oct 2011 08:47:01 -0700 [thread overview]
Message-ID: <CALQRfL4zCbzr_Fa0ySi96j06nw7ifocCxUjYUs6vXxeNvjCutQ@mail.gmail.com> (raw)
In-Reply-To: <20111024144334.GA26603@hallyn.com>
Serge,
It seems as if this whole thing is really idiomatic. How about?
#define IN_ROOT_USER_NS_CAPABLE(cap) \
((current_user_ns() == &init_user_ns) && cap_raised(current_cap(), cap))
Cheers
Andrew
On Mon, Oct 24, 2011 at 7:43 AM, Serge E. Hallyn <serge@hallyn.com> wrote:
> A few modules are using cap_raised(current_cap(), cap) to authorize
> actions. This means that tasks which are privileged in non-initial
> user namespaces will be deemed privileged. The privilege should only
> be granted if the task is in the initial user namespace.
>
> Switching the calls to capable() would change the behavior - it would
> cause the LSM capable hooks to be called, and set PF_SUPERPRIV if
> the capability was used. So instead, put in an explicit check and
> refuse privilege if the caller is not in init_user_ns.
>
> Changelog:
> Oct 23: Use a nice macro to make the code shorter and easier to read,
> per advice from Andrew Morgan and David Howells.
>
> Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
> Cc: Eric W. Biederman <ebiederm@xmission.com>
> Cc: Andrew Morgan <morgan@kernel.org>
> Cc: Vasiliy Kulikov <segoon@openwall.com>
> Cc: David Howells <dhowells@redhat.com>
> ---
> drivers/block/drbd/drbd_nl.c | 2 +-
> drivers/md/dm-log-userspace-transfer.c | 2 +-
> drivers/staging/pohmelfs/config.c | 2 +-
> drivers/video/uvesafb.c | 2 +-
> include/linux/cred.h | 2 ++
> 5 files changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c
> index 0feab26..f799b15 100644
> --- a/drivers/block/drbd/drbd_nl.c
> +++ b/drivers/block/drbd/drbd_nl.c
> @@ -2297,7 +2297,7 @@ static void drbd_connector_callback(struct cn_msg *req, struct netlink_skb_parms
> return;
> }
>
> - if (!cap_raised(current_cap(), CAP_SYS_ADMIN)) {
> + if (!IN_ROOT_USER_NS() || !cap_raised(current_cap(), CAP_SYS_ADMIN)) {
> retcode = ERR_PERM;
> goto fail;
> }
> diff --git a/drivers/md/dm-log-userspace-transfer.c b/drivers/md/dm-log-userspace-transfer.c
> index 1f23e04..126a79b 100644
> --- a/drivers/md/dm-log-userspace-transfer.c
> +++ b/drivers/md/dm-log-userspace-transfer.c
> @@ -134,7 +134,7 @@ static void cn_ulog_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
> {
> struct dm_ulog_request *tfr = (struct dm_ulog_request *)(msg + 1);
>
> - if (!cap_raised(current_cap(), CAP_SYS_ADMIN))
> + if (!IN_ROOT_USER_NS() || !cap_raised(current_cap(), CAP_SYS_ADMIN))
> return;
>
> spin_lock(&receiving_list_lock);
> diff --git a/drivers/staging/pohmelfs/config.c b/drivers/staging/pohmelfs/config.c
> index b6c42cb..327c047 100644
> --- a/drivers/staging/pohmelfs/config.c
> +++ b/drivers/staging/pohmelfs/config.c
> @@ -525,7 +525,7 @@ static void pohmelfs_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *n
> {
> int err;
>
> - if (!cap_raised(current_cap(), CAP_SYS_ADMIN))
> + if (!IN_ROOT_USER_NS() || !cap_raised(current_cap(), CAP_SYS_ADMIN))
> return;
>
> switch (msg->flags) {
> diff --git a/drivers/video/uvesafb.c b/drivers/video/uvesafb.c
> index 7f8472c..94e0e9d 100644
> --- a/drivers/video/uvesafb.c
> +++ b/drivers/video/uvesafb.c
> @@ -73,7 +73,7 @@ static void uvesafb_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *ns
> struct uvesafb_task *utask;
> struct uvesafb_ktask *task;
>
> - if (!cap_raised(current_cap(), CAP_SYS_ADMIN))
> + if (!IN_ROOT_USER_NS() || !cap_raised(current_cap(), CAP_SYS_ADMIN))
> return;
>
> if (msg->seq >= UVESAFB_TASKS_MAX)
> diff --git a/include/linux/cred.h b/include/linux/cred.h
> index 4030896..2f75da7 100644
> --- a/include/linux/cred.h
> +++ b/include/linux/cred.h
> @@ -359,9 +359,11 @@ static inline void put_cred(const struct cred *_cred)
>
> #ifdef CONFIG_USER_NS
> #define current_user_ns() (current_cred_xxx(user_ns))
> +#define IN_ROOT_USER_NS() (current_user_ns() == &init_user_ns)
> #else
> extern struct user_namespace init_user_ns;
> #define current_user_ns() (&init_user_ns)
> +#define IN_ROOT_USER_NS() (1)
> #endif
>
>
> --
> 1.7.5.4
>
>
next prev parent reply other threads:[~2011-10-24 15:47 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-18 21:54 user namespaces: fix some uid/privilege leaks Serge Hallyn
2011-10-18 21:54 ` [PATCH 1/9] pid_ns: ensure pid is not freed during kill_pid_info_as_uid Serge Hallyn
2011-10-18 21:54 ` [PATCH 2/9] user namespace: usb: make usb urbs user namespace aware (v2) Serge Hallyn
2011-10-18 21:54 ` [PATCH 3/9] user namespace: make signal.c respect user namespaces (v4) Serge Hallyn
2011-10-18 21:54 ` [PATCH 4/9] User namespace: don't allow sysctl in non-init user ns (v2) Serge Hallyn
2011-10-18 21:54 ` [PATCH 5/9] user namespace: clamp down users of cap_raised Serge Hallyn
2011-10-19 4:33 ` Andrew G. Morgan
2011-10-20 13:01 ` Serge E. Hallyn
2011-10-19 9:01 ` David Howells
2011-10-20 13:16 ` Serge E. Hallyn
2011-10-24 14:43 ` [PATCH 05/10] " Serge E. Hallyn
2011-10-24 15:47 ` Andrew G. Morgan [this message]
2011-10-24 17:28 ` Serge E. Hallyn
2011-10-25 0:43 ` Andrew G. Morgan
2011-10-25 3:03 ` Serge E. Hallyn
2011-10-25 17:33 ` Eric Paris
2011-10-25 20:09 ` Serge E. Hallyn
2011-10-18 21:54 ` [PATCH 6/9] Add Documentation/namespaces/user_namespace.txt (v3) Serge Hallyn
2011-10-18 21:54 ` [PATCH 7/9] user namespace: make each net (net_ns) belong to a user_ns Serge Hallyn
2011-10-18 21:54 ` [PATCH 8/9] protect cap_netlink_recv from user namespaces Serge Hallyn
2011-10-18 21:54 ` [PATCH 9/9] make net/core/scm.c uid comparisons user namespace aware Serge Hallyn
2011-10-18 22:14 ` Joe Perches
2011-10-18 23:22 ` Serge E. Hallyn
2011-10-19 2:25 ` [PATCH 9/9] make net/core/scm.c uid comparisons user namespace aware (v2) Serge E. Hallyn
2011-10-19 13:52 ` [PATCH 9/9] make net/core/scm.c uid comparisons user namespace aware Eric W. Biederman
2011-10-20 12:58 ` Serge E. Hallyn
2011-10-20 13:35 ` Eric W. Biederman
2011-10-20 14:14 ` Serge E. Hallyn
2011-10-24 4:15 ` Serge E. Hallyn
2011-10-24 4:27 ` Eric W. Biederman
2011-10-20 14:24 ` Serge E. Hallyn
2011-10-19 9:36 ` [PATCH 6/9] Add Documentation/namespaces/user_namespace.txt (v3) David Howells
2011-10-20 12:58 ` Serge E. Hallyn
2011-10-26 20:33 ` [PATCH 06/10] Add Documentation/namespaces/user_namespace.txt (v4) Serge E. Hallyn
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