[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <1346879629.2054.22.camel@falcor.watson.ibm.com>
Date: Wed, 05 Sep 2012 17:13:49 -0400
From: Mimi Zohar <zohar@...ux.vnet.ibm.com>
To: Matthew Garrett <mjg@...hat.com>
Cc: linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org
Subject: Re: [PATCH 07/11] kexec: Disable in a secure boot environment
On Tue, 2012-09-04 at 11:55 -0400, Matthew Garrett wrote:
> kexec could be used as a vector for a malicious user to use a signed kernel
> to circumvent the secure boot trust model. In the long run we'll want to
> support signed kexec payloads, but for the moment we should just disable
> loading entirely in that situation.
>
> Signed-off-by: Matthew Garrett <mjg@...hat.com>
> ---
> kernel/kexec.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/kexec.c b/kernel/kexec.c
> index 0668d58..48852ec 100644
> --- a/kernel/kexec.c
> +++ b/kernel/kexec.c
> @@ -944,7 +944,7 @@ SYSCALL_DEFINE4(kexec_load, unsigned long, entry, unsigned long, nr_segments,
> int result;
>
> /* We only trust the superuser with rebooting the system. */
> - if (!capable(CAP_SYS_BOOT))
> + if (!capable(CAP_SYS_BOOT) || !capable(CAP_SECURE_FIRMWARE))
> return -EPERM;
>
> /*
Normally capabilities provide additional permissions. So if you don't
have the capability, an errno is returned. CAP_SYS_BOOT is a good
example. With CAP_SECURE_FIRMWARE, it reads backwards - if not
CAP_SECURE_FIRMWARE, return error. I think you want to invert the name
to CAP_NOT_SECURE_FIRMWARE, CAP_NOT_SECURE_BOOT or perhaps
CAP_UNSECURED_BOOT.
Mimi
--
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/
Powered by blists - more mailing lists