linux-kernel - Re: [PATCH V3 08/11] kexec: Disable at runtime if the kernel enforces module loading restrictions

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 4 Sep 2013 14:09:59 -0600
From:	jerry.hoemann@...com
To:	Matthew Garrett <matthew.garrett@...ula.com>
Cc:	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	keescook@...omium.org, hpa@...or.com,
	kexec <kexec@...ts.infradead.org>
Subject: Re: [PATCH V3 08/11] kexec: Disable at runtime if the kernel
 enforces module loading restrictions

On Tue, Sep 03, 2013 at 07:50:15PM -0400, Matthew Garrett wrote:
> 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>


Matthew,

Disabling kexec will disable kdump, correct?

Are there plans to enable kdump on a system where secure
boot is enabled?


thanks

Jerry



> ---
>  kernel/kexec.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index 59f7b55..3e2b63a 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>
> @@ -943,6 +944,13 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
>  		return -EPERM;
>  
>  	/*
> +	 * kexec can be used to circumvent module loading restrictions, so
> +	 * prevent loading in that case
> +	 */
> +	if (secure_modules())
> +		return -EPERM;
> +
> +	/*
>  	 * Verify we have a legal set of flags
>  	 * This leaves us room for future extensions.
>  	 */
> -- 
> 1.8.3.1
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-efi" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 

----------------------------------------------------------------------------
Jerry Hoemann            Software Engineer              Hewlett-Packard/MODL

3404 E Harmony Rd. MS 57                        phone:  (970) 898-1022
Ft. Collins, CO 80528                           FAX:    (970) 898-XXXX
                                                email:  jerry.hoemann@...com
----------------------------------------------------------------------------

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/