linux-kernel - Re: [PATCH V2 08/10] kexec: Disable at runtime if the kernel enforces module loading restrictions

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Date:	Thu, 29 Aug 2013 11:57:36 -0400 (EDT)
From:	Lenny Szubowicz <lszubowi@...hat.com>
To:	Matthew Garrett <matthew.garrett@...ula.com>,
	linux-kernel@...r.kernel.org
Cc:	linux-efi@...r.kernel.org, jwboyer@...hat.com,
	keescook@...omium.org
Subject: Re: [PATCH V2 08/10] kexec: Disable at runtime if the kernel
 enforces module loading restrictions



----- Original Message -----
> From: "Matthew Garrett" <matthew.garrett@...ula.com>
> To: linux-kernel@...r.kernel.org
> Cc: linux-efi@...r.kernel.org, jwboyer@...hat.com, keescook@...omium.org, "Matthew Garrett"
> <matthew.garrett@...ula.com>
> Sent: Monday, August 19, 2013 1:26:09 PM
> Subject: [PATCH V2 08/10] kexec: Disable at runtime if the kernel enforces module loading restrictions
> 
> kexec permits the loading and execution of arbitrary code in ring 0, which
> is something that module signing enforcement is meant to prevent. It makes
> sense to disable kexec in this situation.
> 
> Signed-off-by: Matthew Garrett <matthew.garrett@...ula.com>
> ---
>  kernel/kexec.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index 59f7b55..1a7690f 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -32,6 +32,7 @@
>  #include <linux/vmalloc.h>
>  #include <linux/swap.h>
>  #include <linux/syscore_ops.h>
> +#include <linux/module.h>
>  
>  #include <asm/page.h>
>  #include <asm/uaccess.h>
> @@ -1645,6 +1646,9 @@ int kernel_kexec(void)
>  		goto Unlock;
>  	}
>  
> +	if (secure_modules())
> +		return -EPERM;
> +
>  #ifdef CONFIG_KEXEC_JUMP
>  	if (kexec_image->preserve_context) {
>  		lock_system_sleep();
> --
> 1.8.3.1
> 
> --
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> 


Shouldn't that be:

+	if (secure_modules()) {
+		error = -EPERM;
+		goto Unlock;
+	}

-Lenny.
--
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