linux-kernel - Re: [PATCH 0/5 v2][RFC] Encryption and authentication for hibernate snapshot image

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Date:   Sun, 6 Jan 2019 19:10:27 +0100
From:   Pavel Machek <pavel@....cz>
To:     "Lee, Chun-Yi" <joeyli.kernel@...il.com>
Cc:     "Rafael J . Wysocki" <rjw@...ysocki.net>,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        keyrings@...r.kernel.org, "Lee, Chun-Yi" <jlee@...e.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Chen Yu <yu.c.chen@...el.com>,
        Oliver Neukum <oneukum@...e.com>,
        Ryan Chen <yu.chen.surf@...il.com>,
        David Howells <dhowells@...hat.com>,
        Giovanni Gherdovich <ggherdovich@...e.cz>,
        Randy Dunlap <rdunlap@...radead.org>,
        Jann Horn <jannh@...gle.com>, Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH 0/5 v2][RFC] Encryption and authentication for hibernate
 snapshot image

Hi!

> This patchset is the implementation of encryption and authentication
> for hibernate snapshot image. The image will be encrypted by AES and
> authenticated by HMAC.

Ok, so you encrypt. 

> The hibernate function can be used to snapshot memory pages to an image,
> then kernel restores the image to memory space in a appropriate time.
> There have secrets in snapshot image and cracker may modifies it for
> hacking system. Encryption and authentication of snapshot image can protect
> the system.
> 
> Hibernate function requests the master key through key retention service.
> The snapshot master key can be a trusted key or a user defined key. The
> name of snapshot master key is fixed to "swsusp-kmk". User should loads
> swsusp-kmk to kernel by keyctl tool before the hibernation resume.
> e.g. The swsusp-kmk must be loaded before systemd-hibernate-resume

But if userspace has a key, encryption is useless against root.

> The TPM trusted key type is preferred to be the master key. But user
> defined key can also be used for testing or when the platform doesn't
> have TPM. User must be aware that the security of user key relies on
> user space. If the root account be compromised, then the user key will
> easy to be grabbed.

In the TPM case, does userland have access to the key? 

Please explain your security goals.

								Pavel


> Lee, Chun-Yi (5):
>   PM / hibernate: Create snapshot keys handler
>   PM / hibernate: Generate and verify signature for snapshot image
>   PM / hibernate: Encrypt snapshot image
>   PM / hibernate: Erase the snapshot master key in snapshot pages
>   PM / hibernate: An option to request that snapshot image must be
>     authenticated
> 
>  Documentation/admin-guide/kernel-parameters.txt |   6 +
>  include/linux/kernel.h                          |   3 +-
>  kernel/panic.c                                  |   1 +
>  kernel/power/Kconfig                            |  25 +
>  kernel/power/Makefile                           |   1 +
>  kernel/power/hibernate.c                        |  59 ++-
>  kernel/power/power.h                            |  59 +++
>  kernel/power/snapshot.c                         | 576 +++++++++++++++++++++++-
>  kernel/power/snapshot_key.c                     | 312 +++++++++++++
>  kernel/power/swap.c                             |   6 +
>  kernel/power/user.c                             |  12 +
>  11 files changed, 1042 insertions(+), 18 deletions(-)
>  create mode 100644 kernel/power/snapshot_key.c
> 

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

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