From: Mimi Zohar <firstname.lastname@example.org>
To: David Howells <email@example.com>
Cc: Petko Manolov <firstname.lastname@example.org>,
Subject: Re: [PATCH 4/9] KEYS: Allow unrestricted boot-time addition of keys to secondary keyring
Date: Mon, 21 Nov 2016 09:04:55 -0500 [thread overview]
Message-ID: <email@example.com> (raw)
On Thu, 2016-11-17 at 09:56 +0000, David Howells wrote:
> Petko Manolov <firstname.lastname@example.org> wrote:
> > On 16-11-16 18:11:13, David Howells wrote:
> > > Allow keys to be added to the system secondary certificates keyring during
> > > kernel initialisation in an unrestricted fashion. Such keys are implicitly
> > > trusted and don't have their trust chains checked on link.
> > Well, I for one do not explicitly trust these keys. I may even want to
> > completely remove or replace them.
> Fine be me. However, if you remove them all I would guess that you cannot
> perform a secure boot.
> Note that it's to be expected that the keys being loaded from the UEFI
> database cannot have their signatures checked - which is why they would have
> to be implicitly trusted. For the same reason, the kernel does not check the
> signatures on the keys compiled into the kernel image.
Sigh, we've been here before, discussed this before. Different keys
should be trusted at different levels. Nothing has changed. Just
because I trust a key in UEFI for UEFI, doesn't mean that I trust that
same key once the kernel has booted.
This time not only are you bringing the keys from UEFI up to the kernel,
but by adding these keys to the secondary trusted keyring, they are
allowed to add other keys they've signed to the secondary trusted
If the UEFI keys are just for verifying kernel modules, why not define a
separate UEFI keyring, which can be used, if enabled, just for verifying
kernel modules, instead of affecting all signature verification?
IMA's root of trust goes back to UEFI, but transitions to the builtin
kernel keyring and, if enabled, the secondary keyring on boot.
> > > This allows keys in the UEFI database to be added in secure boot mode for
> > > the purposes of module signing.
> > The key import should not be automatic, it should be optional.
> You can argue this either way. There's a config option to allow you to turn
> this on or off. Arguably, this should be split in two: one for the whitelist
> (db, MokListRT) and one for the blacklist (dbx).
By "config", you're not referring to a Kconfig option, but a UEFI db
option, making it hidden/unknown to someone building a kernel. If you
really want to add this support, make it clear and easily seen by
defining a "restrict_link_by_builtin_or_uefi" function.
next prev parent reply other threads:[~2016-11-21 14:05 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-16 18:10 [PATCH 0/9] KEYS: Blacklisting & UEFI database load David Howells
2016-11-16 18:10 ` [PATCH 1/9] KEYS: Add a system blacklist keyring David Howells
2016-11-16 18:10 ` [PATCH 2/9] X.509: Allow X.509 certs to be blacklisted David Howells
2016-11-16 18:11 ` [PATCH 3/9] PKCS#7: Handle blacklisted certificates David Howells
2016-11-16 18:11 ` [PATCH 4/9] KEYS: Allow unrestricted boot-time addition of keys to secondary keyring David Howells
2016-11-17 6:41 ` Petko Manolov
2016-11-17 9:56 ` David Howells
2016-11-17 10:22 ` Petko Manolov
2016-11-17 11:18 ` David Howells
2016-11-21 14:04 ` Mimi Zohar [this message]
2016-11-21 15:17 ` David Howells
2016-11-21 16:24 ` Mimi Zohar
2016-11-16 18:11 ` [PATCH 5/9] efi: Add SHIM and image security database GUID definitions David Howells
2016-11-21 16:07 ` Ard Biesheuvel
2016-11-16 18:11 ` [PATCH 6/9] efi: Add EFI signature data types David Howells
2016-11-16 23:43 ` Mat Martineau
2016-11-17 9:44 ` David Howells
2016-11-21 16:08 ` Ard Biesheuvel
2016-11-16 18:11 ` [PATCH 7/9] efi: Add an EFI signature blob parser David Howells
2016-11-16 18:11 ` [PATCH 8/9] MODSIGN: Import certificates from UEFI Secure Boot David Howells
2016-11-21 16:16 ` Ard Biesheuvel
2016-11-21 16:25 ` Josh Boyer
2016-11-24 19:22 ` James Bottomley
2016-11-24 19:17 ` James Bottomley
2016-12-02 18:57 ` James Bottomley
2016-12-02 20:18 ` Mimi Zohar
2016-11-16 18:11 ` [PATCH 9/9] MODSIGN: Allow the "db" UEFI variable to be suppressed David Howells
2016-11-21 16:18 ` Ard Biesheuvel
2016-11-21 16:26 ` Josh Boyer
2016-11-21 16:42 ` Ard Biesheuvel
2016-11-21 19:05 ` Peter Jones
2016-11-21 19:06 ` Ard Biesheuvel
2016-11-21 19:18 ` Peter Jones
2016-11-21 19:33 ` Ard Biesheuvel
2018-03-06 14:05 ` [PATCH 0/9] KEYS: Blacklisting & UEFI database load Jiri Slaby
2018-03-07 13:18 ` Mimi Zohar
2018-03-07 15:28 ` James Bottomley
2018-03-11 3:20 ` joeyli
2018-03-19 14:12 ` Mimi Zohar
2018-03-27 11:08 ` joeyli
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).