From: Andy Lutomirski <luto@amacapital.net>
To: "Luis R. Rodriguez" <mcgrof@suse.com>
Cc: David Howells <dhowells@redhat.com>,
Andy Lutomirski <luto@kernel.org>,
Rusty Russell <rusty@rustcorp.com.au>,
Michal Marek <mmarek@suse.cz>,
Matthew Garrett <mjg59@srcf.ucam.org>,
keyrings@linux-nfs.org,
Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Seth Forshee <seth.forshee@canonical.com>,
LSM List <linux-security-module@vger.kernel.org>,
David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH 0/8] MODSIGN: Use PKCS#7 for module signatures [ver #4]
Date: Thu, 21 May 2015 15:06:21 -0700 [thread overview]
Message-ID: <CALCETrUC5DAz4vths-zxOb6py-M1bfWVF21_145K89wFiuM60g@mail.gmail.com> (raw)
In-Reply-To: <CAB=NE6UurGCp6QF992nTPW-QPQcpF9_O7LDxKsWToFTeWApy_w@mail.gmail.com>
On Thu, May 21, 2015 at 2:59 PM, Luis R. Rodriguez <mcgrof@suse.com> wrote:
> On Thu, May 21, 2015 at 2:44 PM, Andy Lutomirski <luto@amacapital.net> wrote:
>>
>> One option would be to add another type of verifiable thing. We can
>> verify modules, and we should add firmware to the types of things that
>> can be signed. We could add signing keys, too. IOW, you could ask
>> the kernel to load a signing key with certain rights, and, if they key
>> is validly signed by some other key that has the same rights and has a
>> bit set saying that it can delegate those rights, then the kernel will
>> add that signing key to the keyring.
>>
>> If the general infrastructure were there, this would be very little
>> additional code.
>
> I really like this idea, but I've heard of many great ideas before
> followed by nothing but vaporware. So is it a direct requirement to
> implicate blocking a change for current module signature checking
> strategy to a new one given the concerns you raise, or can we enable
> those who wish to want additional better solutions as the one you
> propose to opt-in to develop those solutions? I like the idea of the
> later given that it seems those using the current module signing
> infrastructure would prefer the change and enabling what you say does
> not seem to be a not possible based on allowing that to be advanced.
>
>From my POV (and keep in mind that I'm not really involved in this
stuff and my POV shouldn't be treated as gospel), a firmware signature
verification should have verification that the signature was intended
to apply to a firmware file with the name being requested as a
requirement. Everything else is nice-to-have.
Given that, I would say that merely shoving firmware files through the
module verifier as-is would not be okay. There's plenty of
flexibility in how you fix it, though. Doing it with PKCS#7
authenticated attributes *gag* would work, but my off-the-cuff guess
is that making that work is actually harder, even on top of David's
patches, than doing it from scratch. PKCS#7 is not easy to work with.
FWIW, openssl rsautl can generate raw PKCS#1 v1.5 signatures (use
-pkcs, not -raw). openssl pkeyutl can do PKCS#1 v2.0 (i.e. PSS)
signatures, but you'd have to write the verifier yourself. The kernel
already has a v1.5 verifier that even follows the best practices that
I remember. (For v2.0, there's a security proof, so an implementation
of the spec is actually secure and there are no "best practices" to
worry about. v1.5 is known insecure if you implement it naively.)
--Andy
next prev parent reply other threads:[~2015-05-21 22:06 UTC|newest]
Thread overview: 71+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-15 12:35 [PATCH 0/8] MODSIGN: Use PKCS#7 for module signatures [ver #4] David Howells
2015-05-15 12:35 ` [PATCH 1/8] X.509: Extract both parts of the AuthorityKeyIdentifier " David Howells
2015-05-15 12:35 ` [PATCH 2/8] X.509: Support X.509 lookup by Issuer+Serial form " David Howells
2015-05-15 12:35 ` [PATCH 3/8] PKCS#7: Allow detached data to be supplied for signature checking purposes " David Howells
2015-05-15 12:35 ` [PATCH 4/8] MODSIGN: Provide a utility to append a PKCS#7 signature to a module " David Howells
2015-05-20 0:50 ` Andy Lutomirski
2015-05-20 13:14 ` David Howells
2015-05-20 16:00 ` Andy Lutomirski
2015-05-15 12:36 ` [PATCH 5/8] MODSIGN: Use PKCS#7 messages as module signatures " David Howells
2015-05-15 12:36 ` [PATCH 6/8] sign-file: Add option to only create signature file " David Howells
2015-05-15 12:36 ` [PATCH 7/8] system_keyring.c doesn't need to #include module-internal.h " David Howells
2015-05-15 12:36 ` [PATCH 8/8] MODSIGN: Extract the blob PKCS#7 signature verifier from module signing " David Howells
2015-05-15 13:46 ` [PATCH 0/8] MODSIGN: Use PKCS#7 for module signatures " David Woodhouse
2015-05-15 16:52 ` [PATCH 1/4] modsign: Abort modules_install when signing fails David Woodhouse
2015-05-19 1:29 ` Mimi Zohar
2015-05-19 6:40 ` Woodhouse, David
2015-05-19 11:45 ` Mimi Zohar
2015-05-19 12:57 ` Woodhouse, David
2015-05-19 13:54 ` Mimi Zohar
2015-05-15 16:53 ` [PATCH 2/4] modsign: Allow external signing key to be specified David Woodhouse
2015-05-15 16:53 ` [PATCH 3/4] modsign: Allow password to be specified for signing key David Woodhouse
2015-05-19 1:37 ` Mimi Zohar
2015-05-15 16:54 ` [PATCH 4/4] modsign: Allow signing key to be PKCS#11 David Woodhouse
2015-05-15 19:07 ` sign-file and detached PKCS#7 firmware signatures David Howells
2015-05-18 23:13 ` Luis R. Rodriguez
2015-05-19 9:25 ` David Howells
2015-05-19 16:19 ` Luis R. Rodriguez
2015-05-19 16:48 ` David Howells
2015-05-19 18:21 ` Luis R. Rodriguez
2015-05-19 18:35 ` Luis R. Rodriguez
2015-05-19 18:47 ` David Howells
2015-05-19 20:12 ` Luis R. Rodriguez
2015-05-19 20:29 ` David Howells
2015-05-15 22:51 ` [PATCH 0/8] MODSIGN: Use PKCS#7 for module signatures [ver #4] Rusty Russell
2015-05-18 12:43 ` [PATCH 4/4] modsign: Allow signing key to be PKCS#11 David Howells
2015-05-19 14:45 ` [PATCH 9/8] modsign: Abort modules_install when signing fails David Woodhouse
2015-05-19 14:45 ` [PATCH 10/8] modsign: Allow password to be specified for signing key David Woodhouse
2015-05-19 15:50 ` Petko Manolov
2015-05-19 16:15 ` David Woodhouse
2015-05-19 16:34 ` Petko Manolov
2015-05-19 18:39 ` Mimi Zohar
2015-05-19 18:48 ` David Howells
2015-05-19 19:14 ` Mimi Zohar
2015-05-19 20:04 ` David Woodhouse
2015-05-19 14:46 ` [PATCH 11/8] modsign: Allow signing key to be PKCS#11 David Woodhouse
2015-05-19 14:46 ` [PATCH 12/8] modsign: Allow external signing key to be specified David Woodhouse
2015-05-19 14:47 ` [PATCH 13/8] modsign: Extract signing cert from CONFIG_MODULE_SIG_KEY if needed David Woodhouse
2015-05-19 15:36 ` [PATCH 10/8] modsign: Allow password to be specified for signing key David Howells
2015-05-20 0:36 ` [PATCH 0/8] MODSIGN: Use PKCS#7 for module signatures [ver #4] Andy Lutomirski
2015-05-20 13:36 ` David Howells
2015-05-20 15:56 ` Andy Lutomirski
2015-05-20 16:21 ` Petko Manolov
2015-05-20 16:41 ` Andy Lutomirski
2015-05-20 16:55 ` Petko Manolov
2015-05-21 21:38 ` Luis R. Rodriguez
2015-05-21 21:44 ` Andy Lutomirski
2015-05-21 21:59 ` Luis R. Rodriguez
2015-05-21 22:06 ` Andy Lutomirski [this message]
2015-05-21 22:16 ` Luis R. Rodriguez
2015-05-21 22:24 ` Andy Lutomirski
2015-05-21 22:31 ` Luis R. Rodriguez
2015-05-21 22:47 ` Andy Lutomirski
2015-05-21 23:01 ` Luis R. Rodriguez
2015-05-21 23:09 ` Andy Lutomirski
2015-05-22 7:56 ` David Howells
2015-05-22 12:42 ` Mimi Zohar
2015-05-22 7:49 ` David Howells
2015-05-22 7:48 ` David Howells
2015-05-22 12:28 ` Mimi Zohar
2015-05-24 10:52 ` Petko Manolov
2015-05-21 13:59 ` David Howells
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