From: David Howells <dhowells@redhat.com>
To: Rusty Russell <rusty@ozlabs.org>
Cc: dhowells@redhat.com, keyrings@linux-nfs.org,
linux-crypto@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, dmitry.kasatkin@intel.com,
zohar@linux.vnet.ibm.com, arjan.van.de.ven@intel.com,
alan.cox@intel.com, Jon Masters <jcm@jonmasters.org>
Subject: Re: [PATCH 21/21] MODSIGN: Apply signature checking to modules on module load [ver #3]
Date: Mon, 12 Dec 2011 01:21:40 +0000 [thread overview]
Message-ID: <26644.1323652900@redhat.com> (raw)
In-Reply-To: <87obvfogc6.fsf@rustcorp.com.au>
Rusty Russell <rusty@ozlabs.org> wrote:
> I think you misunderstand, I'm talking about the modinfo command, not
> the .modinfo section.
Sorry, yes. But why do you need to enhance modinfo?
> But I need to know exactly what these version-dependent mangling of
> modules is. Is it real? Is it more than strip? Is it so hard to fix
> that it makes sense to add 450 lines of dense kernel code to allow
> alteration of a module after signing?
The strip program (as far as I know that's the only binutil that we need worry
about) rearranges and reorders the section, symbol and relocation tables when
it discards stuff, and different versions of strip have done it differently.
There's GNU build ID. gcc/binutils was changed at some point to insert an ELF
note with the time at which the binary was built (something to do with
debuginfo matching, I think), and strip would update this when run on the
binary.
I haven't encountered many other things introducing breakage that wasn't the
fault of the tool doing the breaking - which usually got fixed pretty quickly.
However, you said it should be fairly easy to jump over the ELF parcel to get
to the signature. How do you plan on doing that? I presume you would just
parse sufficient of the ELF to find the theoretical ELF EOF and then look there
for a whole string of signatures - and hope they haven't got removed by some
unanticipated tool before you see the module.
David
next prev parent reply other threads:[~2011-12-12 1:22 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-02 18:42 [RFC][PATCH 00/21] Crypto keys and module signing [ver #3] David Howells
2011-12-02 18:42 ` [PATCH 01/21] MPILIB: Export some more symbols " David Howells
2011-12-02 18:42 ` [PATCH 02/21] MPILIB: Add a missing ENOMEM check " David Howells
2011-12-02 18:43 ` [PATCH 03/21] KEYS: Permit key_serial() to be called with a const key pointer " David Howells
2011-12-02 18:43 ` [PATCH 04/21] KEYS: Move the key config into security/keys/Kconfig " David Howells
2011-12-02 18:43 ` [PATCH 05/21] KEYS: Announce key type (un)registration " David Howells
2011-12-02 18:43 ` [PATCH 06/21] KEYS: Reorganise keys Makefile " David Howells
2011-12-02 18:43 ` [PATCH 07/21] KEYS: Create a key type that can be used for general cryptographic operations " David Howells
2012-01-16 12:53 ` Mimi Zohar
2012-01-17 15:32 ` David Howells
2012-01-18 10:56 ` Kasatkin, Dmitry
2011-12-02 18:44 ` [PATCH 08/21] KEYS: Add signature verification facility " David Howells
2012-01-18 11:20 ` Kasatkin, Dmitry
2012-01-18 12:26 ` David Howells
2012-01-18 13:26 ` Kasatkin, Dmitry
2012-01-18 15:13 ` David Howells
2012-01-18 15:20 ` Kasatkin, Dmitry
2012-01-18 19:59 ` David Howells
2012-01-20 1:52 ` Herbert Xu
2011-12-02 18:44 ` [PATCH 09/21] KEYS: Asymmetric public-key algorithm crypto key subtype " David Howells
2011-12-02 18:44 ` [PATCH 10/21] KEYS: DSA signature verification algorithm " David Howells
2011-12-02 18:44 ` [PATCH 11/21] KEYS: RSA " David Howells
2011-12-02 18:44 ` [PATCH 12/21] PGPLIB: PGP definitions (RFC 4880) " David Howells
2011-12-02 18:45 ` [PATCH 13/21] PGPLIB: Basic packet parser " David Howells
2011-12-02 18:45 ` [PATCH 14/21] PGPLIB: Signature " David Howells
2011-12-02 18:45 ` [PATCH 15/21] KEYS: PGP data " David Howells
2011-12-02 18:45 ` [PATCH 16/21] KEYS: PGP-based public key signature verification " David Howells
2012-01-18 11:36 ` Kasatkin, Dmitry
2012-01-18 12:49 ` David Howells
2012-01-18 13:34 ` Kasatkin, Dmitry
2011-12-02 18:46 ` [PATCH 17/21] KEYS: PGP format signature parser " David Howells
2011-12-02 18:46 ` [PATCH 18/21] KEYS: Provide a function to load keys from a PGP keyring blob " David Howells
2011-12-02 18:46 ` [PATCH 19/21] MODSIGN: Add indications of module ELF types " David Howells
2011-12-02 18:46 ` [PATCH 20/21] MODSIGN: Module ELF verifier " David Howells
2011-12-02 18:46 ` [PATCH 21/21] MODSIGN: Apply signature checking to modules on module load " David Howells
2011-12-09 11:18 ` Rusty Russell
2011-12-09 18:43 ` David Howells
2011-12-10 7:01 ` Rusty Russell
2011-12-10 18:37 ` Arjan van de Ven
2011-12-11 4:59 ` Rusty Russell
2011-12-10 14:08 ` David Howells
2011-12-11 4:57 ` Rusty Russell
2011-12-12 1:21 ` David Howells [this message]
2011-12-12 9:09 ` Rusty Russell
2011-12-12 16:11 ` David Howells
2011-12-13 2:15 ` Rusty Russell
2011-12-15 0:14 ` David Howells
2011-12-16 0:41 ` Rusty Russell
2012-01-08 22:02 ` [RFC][PATCH 00/21] Crypto keys and module signing " Mimi Zohar
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