linux-kernel - Re: [PATCH 09/27] uswsusp: Disable when the kernel is locked down

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Date:   Fri, 20 Oct 2017 14:41:09 +0800
From:   joeyli <jlee@...e.com>
To:     David Howells <dhowells@...hat.com>
Cc:     linux-security-module@...r.kernel.org, gnomes@...rguk.ukuu.org.uk,
        linux-efi@...r.kernel.org, matthew.garrett@...ula.com,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        jforbes@...hat.com
Subject: Re: [PATCH 09/27] uswsusp: Disable when the kernel is locked down

On Thu, Oct 19, 2017 at 03:51:42PM +0100, David Howells wrote:
> From: Matthew Garrett <mjg59@...f.ucam.org>
> 
> uswsusp allows a user process to dump and then restore kernel state, which
> makes it possible to modify the running kernel.  Disable this if the kernel
> is locked down.
> 
> Signed-off-by: Matthew Garrett <mjg59@...f.ucam.org>
> Signed-off-by: David Howells <dhowells@...hat.com>
> cc: linux-pm@...r.kernel.org

I have reviewed and tested this patch. Please feel free to add:

Reviewed-by: "Lee, Chun-Yi" <jlee@...e.com>

Thanks a lot!
Joey Lee

> ---
> 
>  kernel/power/user.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/kernel/power/user.c b/kernel/power/user.c
> index 22df9f7ff672..678ade9decfe 100644
> --- a/kernel/power/user.c
> +++ b/kernel/power/user.c
> @@ -52,6 +52,9 @@ static int snapshot_open(struct inode *inode, struct file *filp)
>  	if (!hibernation_available())
>  		return -EPERM;
>  
> +	if (kernel_is_locked_down("/dev/snapshot"))
> +		return -EPERM;
> +
>  	lock_system_sleep();
>  
>  	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
> 
> --
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