[PATCH V34 10/29] hibernate: Disable when the kernel is locked down

[PATCH V34 10/29] hibernate: Disable when the kernel is locked down

[Matthew Garrett]

From: Josh Boyer <jwboyer@fedoraproject.org>

There is currently no way to verify the resume image when returning
from hibernate.  This might compromise the signed modules trust model,
so until we can work with signed hibernate images we disable it when the
kernel is locked down.

Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Matthew Garrett <mjg59@google.com>
Cc: rjw@rjwysocki.net
Cc: pavel@ucw.cz
cc: linux-pm@vger.kernel.org
---
 include/linux/security.h     | 1 +
 kernel/power/hibernate.c     | 3 ++-
 security/lockdown/lockdown.c | 1 +
 3 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index 00a31ab2e5ba..a051f21a1144 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -85,6 +85,7 @@ enum lockdown_reason {
 	LOCKDOWN_MODULE_SIGNATURE,
 	LOCKDOWN_DEV_MEM,
 	LOCKDOWN_KEXEC,
+	LOCKDOWN_HIBERNATION,
 	LOCKDOWN_INTEGRITY_MAX,
 	LOCKDOWN_CONFIDENTIALITY_MAX,
 };
diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index abef759de7c8..3a9cb2d3da4a 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -32,6 +32,7 @@
 #include <linux/ctype.h>
 #include <linux/genhd.h>
 #include <linux/ktime.h>
+#include <linux/security.h>
 #include <trace/events/power.h>
 
 #include "power.h"
@@ -70,7 +71,7 @@ static const struct platform_hibernation_ops *hibernation_ops;
 
 bool hibernation_available(void)
 {
-	return (nohibernate == 0);
+	return nohibernate == 0 && !security_locked_down(LOCKDOWN_HIBERNATION);
 }
 
 /**
diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
index 08fcd8116db3..ce5b3da9bd09 100644
--- a/security/lockdown/lockdown.c
+++ b/security/lockdown/lockdown.c
@@ -21,6 +21,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
 	[LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
 	[LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
 	[LOCKDOWN_KEXEC] = "kexec of unsigned images",
+	[LOCKDOWN_HIBERNATION] = "hibernation",
 	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
 	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
 };
-- 
2.22.0.410.gd8fdbe21b5-goog

Re: [PATCH V34 10/29] hibernate: Disable when the kernel is locked down

[Pavel Machek]

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On Fri 2019-06-21 17:03:39, Matthew Garrett wrote:
> From: Josh Boyer <jwboyer@fedoraproject.org>
> 
> There is currently no way to verify the resume image when returning
> from hibernate.  This might compromise the signed modules trust model,
> so until we can work with signed hibernate images we disable it when the
> kernel is locked down.

I keep getting these...

IIRC suse has patches to verify the images.
								Pavel 



-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Re: [PATCH V34 10/29] hibernate: Disable when the kernel is locked down

[Jiri Kosina]

On Sat, 22 Jun 2019, Pavel Machek wrote:

> > There is currently no way to verify the resume image when returning
> > from hibernate.  This might compromise the signed modules trust model,
> > so until we can work with signed hibernate images we disable it when the
> > kernel is locked down.
> 
> I keep getting these...
> 
> IIRC suse has patches to verify the images.

Yeah, Joey Lee is taking care of those. CCing.

-- 
Jiri Kosina
SUSE Labs

Re: [PATCH V34 10/29] hibernate: Disable when the kernel is locked down

[joeyli]

Hi experts,

On Mon, Jun 24, 2019 at 03:21:23PM +0200, Jiri Kosina wrote:
> On Sat, 22 Jun 2019, Pavel Machek wrote:
> 
> > > There is currently no way to verify the resume image when returning
> > > from hibernate.  This might compromise the signed modules trust model,
> > > so until we can work with signed hibernate images we disable it when the
> > > kernel is locked down.
> > 
> > I keep getting these...
> > 
> > IIRC suse has patches to verify the images.
> 
> Yeah, Joey Lee is taking care of those. CCing.
>

The last time that I sent for hibernation encryption and authentication is
here:
    https://lkml.org/lkml/2019/1/3/281

It needs some big changes after review:
 - Simplify the design: remove keyring dependency and trampoline.
 - Encrypted whole snapshot image instead of only data pages.
 - Using TPM:
        - Direct use TPM API in hibernation instead of keyring
        - Localities (suggested by James Bottomley)

I am still finding enough time to implement those changes, especial TPM
parts.

Thanks
Joey Lee

Re: [PATCH V34 10/29] hibernate: Disable when the kernel is locked down

[Kees Cook]

On Fri, Jun 21, 2019 at 05:03:39PM -0700, Matthew Garrett wrote:
> From: Josh Boyer <jwboyer@fedoraproject.org>
> 
> There is currently no way to verify the resume image when returning
> from hibernate.  This might compromise the signed modules trust model,
> so until we can work with signed hibernate images we disable it when the
> kernel is locked down.
> 
> Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>

Reviewed-by: Kees Cook <keescook@chromium.org>

-Kees

> Signed-off-by: David Howells <dhowells@redhat.com>
> Signed-off-by: Matthew Garrett <mjg59@google.com>
> Cc: rjw@rjwysocki.net
> Cc: pavel@ucw.cz
> cc: linux-pm@vger.kernel.org
> ---
>  include/linux/security.h     | 1 +
>  kernel/power/hibernate.c     | 3 ++-
>  security/lockdown/lockdown.c | 1 +
>  3 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/security.h b/include/linux/security.h
> index 00a31ab2e5ba..a051f21a1144 100644
> --- a/include/linux/security.h
> +++ b/include/linux/security.h
> @@ -85,6 +85,7 @@ enum lockdown_reason {
>  	LOCKDOWN_MODULE_SIGNATURE,
>  	LOCKDOWN_DEV_MEM,
>  	LOCKDOWN_KEXEC,
> +	LOCKDOWN_HIBERNATION,
>  	LOCKDOWN_INTEGRITY_MAX,
>  	LOCKDOWN_CONFIDENTIALITY_MAX,
>  };
> diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
> index abef759de7c8..3a9cb2d3da4a 100644
> --- a/kernel/power/hibernate.c
> +++ b/kernel/power/hibernate.c
> @@ -32,6 +32,7 @@
>  #include <linux/ctype.h>
>  #include <linux/genhd.h>
>  #include <linux/ktime.h>
> +#include <linux/security.h>
>  #include <trace/events/power.h>
>  
>  #include "power.h"
> @@ -70,7 +71,7 @@ static const struct platform_hibernation_ops *hibernation_ops;
>  
>  bool hibernation_available(void)
>  {
> -	return (nohibernate == 0);
> +	return nohibernate == 0 && !security_locked_down(LOCKDOWN_HIBERNATION);
>  }
>  
>  /**
> diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c
> index 08fcd8116db3..ce5b3da9bd09 100644
> --- a/security/lockdown/lockdown.c
> +++ b/security/lockdown/lockdown.c
> @@ -21,6 +21,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
>  	[LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
>  	[LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
>  	[LOCKDOWN_KEXEC] = "kexec of unsigned images",
> +	[LOCKDOWN_HIBERNATION] = "hibernation",
>  	[LOCKDOWN_INTEGRITY_MAX] = "integrity",
>  	[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
>  };
> -- 
> 2.22.0.410.gd8fdbe21b5-goog
> 

-- 
Kees Cook