From: Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH 15/18] Hibernate: adapt to UEFI secure boot with
 signature check
Date: Sun, 25 Aug 2013 18:42:19 +0200
Message-ID: <20130825164219.GK5171@amd.pavel.ucw.cz>
References: <1377169317-5959-1-git-send-email-jlee@suse.com>
 <1377169317-5959-16-git-send-email-jlee@suse.com>
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Cc: linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org,
	linux-pm@vger.kernel.org, linux-crypto@vger.kernel.org,
	opensuse-kernel@opensuse.org, David Howells <dhowells@redhat.com>,
	"Rafael J. Wysocki" <rjw@sisk.pl>,
	Matthew Garrett <mjg59@srcf.ucam.org>,
	Len Brown <len.brown@intel.com>,
	Josh Boyer <jwboyer@redhat.com>,
	Vojtech Pavlik <vojtech@suse.cz>,
	Matt Fleming <matt.fleming@intel.com>,
	James Bottomley <james.bottomley@hansenpartnership.com>,
	Greg KH <gregkh@linuxfoundation.org>, JKosina@suse.com,
	Rusty Russell <rusty@rustcorp.com.au>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	"H. Peter Anvin" <hpa@zytor.com>, Michal Marek <mmarek@suse.cz>,
	Gary Lin <GLin@suse.com>, Vivek Goyal <vgoyal@redhat.com>,
	"Lee, Chun-Yi" <jlee@suse.com>
To: "Lee, Chun-Yi" <joeyli.kernel@gmail.com>
Return-path: <linux-pm-owner@vger.kernel.org>
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In-Reply-To: <1377169317-5959-16-git-send-email-jlee@suse.com>
Sender: linux-pm-owner@vger.kernel.org
List-Id: linux-crypto.vger.kernel.org

On Thu 2013-08-22 19:01:54, Lee, Chun-Yi wrote:
> In current solution, the snapshot signature check used the RSA key-pair
> that are generated by bootloader(e.g. shim) and pass the key-pair to
> kernel through EFI variables. I choice to binding the snapshot
> signature check mechanism with UEFI secure boot for provide stronger
> protection of hibernate. Current behavior is following:
> 
>  + UEFI Secure Boot ON, Kernel found key-pair from shim:
>    Will do the S4 signature check.
> 
>  + UEFI Secure Boot ON, Kernel didn't find key-pair from shim:
>    Will lock down S4 function.
> 
>  + UEFI Secure Boot OFF
>    Will NOT do the S4 signature check.
>    Ignore any keys from bootloader.
> 
> v2:
> Replace sign_key_data_loaded() by skey_data_available() to check sign key data
> is available for hibernate.
> 
> Reviewed-by: Jiri Kosina <jkosina@suse.cz>
> Signed-off-by: Lee, Chun-Yi <jlee@suse.com>
> ---
>  kernel/power/hibernate.c |   36 +++++++++++++++++-
>  kernel/power/main.c      |   11 +++++-
>  kernel/power/snapshot.c  |   95 ++++++++++++++++++++++++++--------------------
>  kernel/power/swap.c      |    4 +-
>  kernel/power/user.c      |   11 +++++
>  5 files changed, 112 insertions(+), 45 deletions(-)
> 
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index c545b15..0f19f3d 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -29,6 +29,7 @@
>  #include <linux/ctype.h>
>  #include <linux/genhd.h>
>  #include <linux/key.h>
> +#include <linux/efi.h>
>  
>  #include "power.h"
>  
> @@ -632,7 +633,14 @@ static void power_down(void)
>  int hibernate(void)
>  {
>  	int error;
> -	int skey_error;
> +
> +#ifdef CONFIG_SNAPSHOT_VERIFICATION
> +	if (!capable(CAP_COMPROMISE_KERNEL) && !skey_data_available()) {
> +#else
> +	if (!capable(CAP_COMPROMISE_KERNEL)) {
> +#endif
> +		return -EPERM;
> +	}
>  
>  	lock_system_sleep();
>  	/* The snapshot device should not be opened while we're running */
> @@ -799,6 +807,15 @@ static int software_resume(void)
>  	if (error)
>  		goto Unlock;
>  
> +#ifdef CONFIG_SNAPSHOT_VERIFICATION
> +	if (!capable(CAP_COMPROMISE_KERNEL) && !wkey_data_available()) {
> +#else
> +	if (!capable(CAP_COMPROMISE_KERNEL)) {
> +#endif
> +		mutex_unlock(&pm_mutex);
> +		return -EPERM;
> +	}
> +
>  	/* The snapshot device should not be opened while we're running */
>  	if (!atomic_add_unless(&snapshot_device_available, -1, 0)) {
>  		error = -EBUSY;
> @@ -892,6 +909,15 @@ static ssize_t disk_show(struct kobject *kobj, struct kobj_attribute *attr,
>  	int i;
>  	char *start = buf;
>  
> +#ifdef CONFIG_SNAPSHOT_VERIFICATION
> +	if (efi_enabled(EFI_SECURE_BOOT) && !skey_data_available()) {
> +#else
> +	if (efi_enabled(EFI_SECURE_BOOT)) {
> +#endif
> +		buf += sprintf(buf, "[%s]\n", "disabled");
> +		return buf-start;
> +	}
> +
>  	for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
>  		if (!hibernation_modes[i])
>  			continue;
> @@ -926,6 +952,14 @@ static ssize_t disk_store(struct kobject *kobj, struct kobj_attribute *attr,
>  	char *p;
>  	int mode = HIBERNATION_INVALID;
>  
> +#ifdef CONFIG_SNAPSHOT_VERIFICATION
> +	if (!capable(CAP_COMPROMISE_KERNEL) && !skey_data_available()) {
> +#else
> +	if (!capable(CAP_COMPROMISE_KERNEL)) {
> +#endif
> +		return -EPERM;
> +	}
> +
>  	p = memchr(buf, '\n', n);
>  	len = p ? p - buf : n;
>  

You clearly need some helper function.
									Pavel

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