From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Johannes Berg <johannes@sipsolutions.net>,
Kyle McMartin <kyle@kernel.org>,
Jason Cooper <jason@lakedaemon.net>,
"ksummit-discuss@lists.linuxfoundation.org"
<ksummit-discuss@lists.linuxfoundation.org>,
Mark Brown <broonie@sirena.org.uk>
Subject: Re: [Ksummit-discuss] Last minute nominations: mcgrof and toshi
Date: Tue, 02 Aug 2016 14:12:43 -0400 [thread overview]
Message-ID: <1470161563.2485.36.camel@HansenPartnership.com> (raw)
In-Reply-To: <CALCETrUnhQ_4J_hOBG-Z5aSbF=rEkKckbnA46PUs1ZL0vY3Uew@mail.gmail.com>
On Mon, 2016-08-01 at 18:23 -0700, Andy Lutomirski wrote:
> On Mon, Aug 1, 2016 at 6:13 PM, James Bottomley
> <James.Bottomley@hansenpartnership.com> wrote:
> > On Mon, 2016-08-01 at 17:48 -0700, Andy Lutomirski wrote:
> > > [1] The authattr mechanism isn't internally domain-separated, so
> > > signatures with authattrs can be used to generate valid
> > > signatures over invalid data. I think David Howells worked around
> > > this in the kernel after I pointed it out.
> >
> > How? The only fiddle I can see you doing is swapping empty
> > attributes for data and vice versa.
>
> Every valid PKCS#7 signature with authattrs is also a valid PKCS#7
> without authattrs over a messy ASN.1 object that contains the
> authattrs. They forgot to make the thing that's fed to the raw
> signature primitive distinct for the two modes.
OK, I accept this, but for PKCS7 signatures, the signing and hashing
algorithms are required to be part of the authenticated attributes, so
this means that if they're missing we know the packet is invalid, so
this attack should be unavailable against signed firmware.
James
next prev parent reply other threads:[~2016-08-02 18:12 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-04 15:26 Luis R. Rodriguez
2015-08-04 22:20 ` Toshi Kani
2016-07-15 19:50 ` Mimi Zohar
2016-07-15 19:57 ` Mimi Zohar
2016-07-16 0:52 ` Mark Brown
2016-07-26 14:42 ` David Woodhouse
2016-07-27 14:04 ` [Ksummit-discuss] [TECH TOPIC] Signature management - keys, modules, firmware, was: " Jason Cooper
2016-07-27 14:58 ` Mark Rutland
2016-07-27 18:17 ` Stephen Hemminger
2016-07-27 18:36 ` Andy Lutomirski
2016-07-29 12:29 ` Ben Hutchings
2016-08-05 17:16 ` Mimi Zohar
2016-08-05 18:24 ` Ben Hutchings
2016-08-02 12:54 ` Linus Walleij
2016-08-02 14:00 ` Jason Cooper
2016-08-02 14:09 ` David Woodhouse
[not found] ` <CALCETrUjn7TeGbS4TQ+OFih-nby2Rh54i5177MOwqjTYDBMO=A@mail.gmail.com>
[not found] ` <CALCETrU6aQ5PR_+M7QHkTWos6i6vVS2nvEQDwr5ktBkWu-5MKw@mail.gmail.com>
[not found] ` <CALCETrW8uRK4cuQ+B6NPcO0pY-=-HRDf4LZk4xv2QdPzNEvMCg@mail.gmail.com>
[not found] ` <CALCETrW_mQLmR6g_Ar8Nnpr7CRFZhth=Hj9C901Gj7_WSp=yEQ@mail.gmail.com>
2016-08-02 14:53 ` Andy Lutomirski
2016-08-02 14:13 ` James Bottomley
2016-08-03 9:47 ` Linus Walleij
2016-08-03 10:00 ` Jiri Kosina
2016-08-03 10:28 ` Jani Nikula
2016-08-03 10:41 ` Linus Walleij
2016-08-03 11:18 ` Jani Nikula
2016-08-03 15:19 ` Jason Cooper
2016-08-12 12:38 ` Vinod Koul
2016-08-12 12:39 ` David Woodhouse
2016-08-12 12:54 ` Andy Lutomirski
2016-08-12 13:00 ` David Woodhouse
2016-08-12 13:12 ` Vinod Koul
2016-07-27 14:08 ` David Howells
2016-07-27 14:10 ` Ard Biesheuvel
2016-07-27 14:23 ` Mark Brown
2016-07-27 15:06 ` [Ksummit-discuss] " James Bottomley
2016-08-01 10:22 ` Johannes Berg
2016-07-27 15:37 ` David Howells
2016-07-27 16:14 ` James Bottomley
2016-07-27 17:57 ` Andy Lutomirski
2016-07-27 19:00 ` James Bottomley
2016-07-27 19:20 ` Andy Lutomirski
2016-07-27 19:50 ` James Bottomley
2016-07-27 16:07 ` David Howells
2016-07-27 16:25 ` James Bottomley
2016-07-27 16:10 ` David Howells
2016-07-27 16:14 ` David Howells
2016-07-27 16:28 ` James Bottomley
2016-07-27 16:36 ` James Bottomley
2016-07-27 17:20 ` Luis R. Rodriguez
2016-07-27 17:51 ` James Bottomley
2016-07-27 18:57 ` Luis R. Rodriguez
2016-07-27 19:37 ` Mimi Zohar
2016-07-27 20:09 ` Andy Lutomirski
2016-07-27 22:54 ` Mimi Zohar
2016-07-27 23:15 ` Andy Lutomirski
2016-07-28 3:17 ` Mimi Zohar
2016-07-28 3:29 ` Andy Lutomirski
2016-07-28 16:57 ` Jason Cooper
2016-07-29 22:10 ` Mimi Zohar
2016-07-29 22:25 ` Andy Lutomirski
2016-07-30 16:36 ` Luis R. Rodriguez
2016-07-31 3:08 ` Mimi Zohar
2016-07-31 3:09 ` Andy Lutomirski
2016-07-31 15:31 ` Mimi Zohar
2016-07-31 16:19 ` Andy Lutomirski
2016-07-31 17:28 ` Mimi Zohar
2016-07-31 18:20 ` Andy Lutomirski
2016-08-01 1:52 ` Mimi Zohar
2016-08-01 17:29 ` Luis R. Rodriguez
2016-08-01 17:59 ` Andy Lutomirski
2016-08-01 20:23 ` Luis R. Rodriguez
2016-08-01 20:37 ` Andy Lutomirski
2016-08-01 20:57 ` Luis R. Rodriguez
2016-08-01 21:14 ` Andy Lutomirski
2016-08-01 22:56 ` Jason Cooper
2016-08-01 23:12 ` Andy Lutomirski
2016-08-02 0:33 ` James Bottomley
[not found] ` <CALCETrXHfUULy-EB13Kbkjwco-2UVgsuRsG+OicZT6_uOkzeqA@mail.gmail.com>
[not found] ` <CALCETrWqpQV1AyxVx5eTkJiOe3t7ZFpSAuN2RG3JNHD-gqm0uA@mail.gmail.com>
2016-08-02 0:48 ` Andy Lutomirski
2016-08-02 1:13 ` James Bottomley
2016-08-02 1:23 ` Andy Lutomirski
2016-08-02 18:12 ` James Bottomley [this message]
2016-08-01 22:21 ` Mimi Zohar
2016-08-01 22:36 ` Andy Lutomirski
2016-08-01 23:02 ` Mimi Zohar
2016-08-01 23:04 ` Jason Cooper
2016-08-01 23:13 ` Andy Lutomirski
2016-08-01 23:30 ` Jason Cooper
[not found] ` <CALCETrWDsMdU2-AWQC4wYvotnNd2ydWT15Ckq0nZaNRJZOtZ-g@mail.gmail.com>
[not found] ` <CALCETrW-P8+yGuEgM2BT+aCfZqJ=ekB2Xsz+4xhWtdRpprJHNw@mail.gmail.com>
2016-08-01 23:45 ` Andy Lutomirski
2016-08-02 12:20 ` Jason Cooper
[not found] ` <CALCETrVEY=opRPGKy=P9h8s+TC_K19WnBJ2svXT+=_FnqRF1Mw@mail.gmail.com>
[not found] ` <CALCETrVZtn_SmeN1YX9_+2g+bEAHsfJJ7KQH7-eC_mU3O+0x2w@mail.gmail.com>
2016-08-02 15:07 ` Andy Lutomirski
2016-08-03 16:44 ` Jason Cooper
2016-08-03 17:20 ` Andy Lutomirski
2016-08-03 17:50 ` Jason Cooper
2016-08-01 17:15 ` Luis R. Rodriguez
2016-08-02 18:55 ` Andy Lutomirski
2016-08-02 19:02 ` Ard Biesheuvel
2016-08-02 19:08 ` Andy Lutomirski
2016-08-02 19:14 ` Ard Biesheuvel
2016-08-02 19:17 ` Andy Lutomirski
2016-08-02 19:20 ` Ard Biesheuvel
2016-08-02 20:22 ` Ard Biesheuvel
2016-07-29 12:43 ` Ben Hutchings
2016-07-29 17:57 ` Mimi Zohar
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