linux-kernel - Re: [PATCH 09/12] uswsusp: Disable when trusted

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Message-ID: <CAGXu5jKZykZrSBGOHr5VC+h8F_3R8jM0WFZ+UkG8autHGx5_OA@mail.gmail.com>
Date:	Mon, 16 Mar 2015 14:36:47 -0700
From:	Kees Cook <keescook@...omium.org>
To:	Matthew Garrett <matthew.garrett@...ula.com>
Cc:	linux-security-module <linux-security-module@...r.kernel.org>,
	James Morris <james.l.morris@...cle.com>,
	"Serge E. Hallyn" <serge@...lyn.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...or.com>,
	"gnomes@...rguk.ukuu.org.uk" <gnomes@...rguk.ukuu.org.uk>
Subject: Re: [PATCH 09/12] uswsusp: Disable when trusted_kernel is true

On Fri, Mar 13, 2015 at 2:38 PM, Matthew Garrett
<matthew.garrett@...ula.com> wrote:
> uswsusp allows a user process to dump and then restore kernel state, which
> makes it possible to modify the running kernel. Disable this if
> trusted_kernel is true.
>
> Signed-off-by: Matthew Garrett <matthew.garrett@...ula.com>
> ---
>  kernel/power/user.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/power/user.c b/kernel/power/user.c
> index 526e891..43b7b59 100644
> --- a/kernel/power/user.c
> +++ b/kernel/power/user.c
> @@ -24,6 +24,7 @@
>  #include <linux/console.h>
>  #include <linux/cpu.h>
>  #include <linux/freezer.h>
> +#include <linux/security.h>
>
>  #include <asm/uaccess.h>
>
> @@ -49,7 +50,7 @@ static int snapshot_open(struct inode *inode, struct file *filp)
>         struct snapshot_data *data;
>         int error;
>
> -       if (!hibernation_available())
> +       if (get_trusted_kernel() || !hibernation_available())
>                 return -EPERM;
>
>         lock_system_sleep();
> --
> 2.1.0
>

Perhaps this should be folded into the hibernation_available check
instead of added as an "||" check here?

-Kees


-- 
Kees Cook
Chrome OS Security
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