linux-kernel - PKCS#7 parser and MS SpcSpOpusInfo OID

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Date:	Mon, 18 Jan 2016 15:54:33 +0100
From:	Juerg Haefliger <juergh@...il.com>
To:	LKML <linux-kernel@...r.kernel.org>
Subject: PKCS#7 parser and MS SpcSpOpusInfo OID

Hi,

The pkcs7 kernel parser currently checks for the following AuthAttrs
(in pkcs7_sig_note_set_of_authattrs()):

(ctx->msg->data_type == OID_msIndirectData &&
!test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set))

This check passes for an MS signtool signed kernel but not for an sbsign
signed kernel. The sbsign'ed kernel signature doesn't contain an SpcSpOpusInfo
structure.

signtool signature:
$ dumpasn1 signtool.sig | grep '1 3 6 1 4 1 311'
         :           spcIndirectDataContext (1 3 6 1 4 1 311 2 1 4)
         :                 spcPEImageData (1 3 6 1 4 1 311 2 1 15)
         :                 spcSpOpusInfo (1 3 6 1 4 1 311 2 1 12)
         :                   spcIndirectDataContext (1 3 6 1 4 1 311 2 1 4)
         :                 spcStatementType (1 3 6 1 4 1 311 2 1 11)
         :                     individualCodeSigning (1 3 6 1 4 1 311 2 1 21)

sbsign signature:
$ dumpasn1 sbsign.sig | grep '1 3 6 1 4 1 311'
         :           spcIndirectDataContext (1 3 6 1 4 1 311 2 1 4)
         :                 spcPEImageData (1 3 6 1 4 1 311 2 1 15)
         :                   spcIndirectDataContext (1 3 6 1 4 1 311 2 1 4)

Is the check too restrictive or is sbsign doing something wrong? What am I
missing?

Thanks
...Juerg

--
Juerg Haefliger
Hewlett Packard Enterprise