Re: [PATCH v3] X.509: Support parse long form of length octets in Authority Key Identifier

[Rusty Russell]

"Lee, Chun-Yi" <joeyli.kernel@xxxxxxxxx> writes:
> From: Chun-Yi Lee <jlee@xxxxxxxx>
>
> Per X.509 spec in 4.2.1.1 section, the structure of Authority Key
> Identifier Extension is:
>
>    AuthorityKeyIdentifier ::= SEQUENCE {
>       keyIdentifier             [0] KeyIdentifier           OPTIONAL,
>       authorityCertIssuer       [1] GeneralNames            OPTIONAL,
>       authorityCertSerialNumber [2] CertificateSerialNumber OPTIONAL  }
>
>    KeyIdentifier ::= OCTET STRING
>
> When a certificate also provides
> authorityCertIssuer and authorityCertSerialNumber then the length of
> AuthorityKeyIdentifier SEQUENCE is likely to long form format.
> e.g.
>    The example certificate demos/tunala/A-server.pem in openssl source:
>
> X509v3 Authority Key Identifier:
>     keyid:49:FB:45:72:12:C4:CC:E1:45:A1:D3:08:9E:95:C4:2C:6D:55:3F:17
>     DirName:/C=NZ/L=Wellington/O=Really Irresponsible Authorisation Authority (RIAA)/OU=Cert-stamping/CN=Jackov al-Trades/emailAddress=none@xxxxxxxxxxx
>     serial:00
>
> Current parsing rule of OID_authorityKeyIdentifier only take care the
> short form format, it causes load certificate to modsign_keyring fail:
>
> [   12.061147] X.509: Extension: 47
> [   12.075121] MODSIGN: Problem loading in-kernel X.509 certificate (-74)
>
> So, this patch add the parsing rule for support long form format against
> Authority Key Identifier.
>
> v3:
> Changed the size check in "Short Form length" case, we allow v[3] smaller
> then (vlen - 4) because authorityCertIssuer and authorityCertSerialNumber
> are also possible attach in AuthorityKeyIdentifier sequence.
>
> v2:
>  - Removed comma from author's name.
>  - Moved 'Short Form length' comment inside the if-body.
>  - Changed the type of sub to size_t.
>  - Use ASN1_INDEFINITE_LENGTH rather than writing 0x80 and 127.
>  - Moved the key_len's value assignment before alter v.
>  - Fixed the typo of octets.
>  - Add 2 to v before entering the loop for calculate the length.
>  - Removed the comment of check vlen.
>
> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
> Cc: Josh Boyer <jwboyer@xxxxxxxxxx>
> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxx>
> Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
> Acked-by: David Howells <dhowells@xxxxxxxxxx>
> Signed-off-by: Chun-Yi Lee <jlee@xxxxxxxx>

Applied to modules-next.

Thanks,
Rusty.
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