Re: [PATCH v3 00/14] KEYS: Add support for PGP keys and signatures

David Howells
2024-09-13T09:32:42Z

Herbert Xu <herbert@gondor.apana.org.au> wrote:

> Personally I don't think the argument above holds water. With
> IPsec we had a similar issue of authenticating untrusted peers
> using public key cryptography. In that case we successfully
> delegated the task to user-space and it is still how it works
> to this day.

It transpires that we do actually need at least a PGP parser in the kernel -
and it needs to be used prior to loading any modules: some Lenovo Thinkpads,
at least, may have EFI variables holding a list of keys in PGP form, not X.509
form.

For example, in dmesg, you might see:

May 16 04:01:01 localhost kernel: integrity: Loading X.509 certificate: UEFI:MokListRT (MOKvar table)
May 16 04:01:01 localhost kernel: integrity: Problem loading X.509 certificate -126

On my laptop, if I dump this variable:

efivar -e /tmp/q --name=605dab50-e046-4300-abb6-3dd810dd8b23-MokListRT

And then looking at the data exported:

file /tmp/q

I see:

/tmp/q: PGP Secret Sub-key -

The kernel doesn't currently have a PGP parser. I've checked and the value
doesn't parse as ASN.1:

openssl asn1parse -in /tmp/q -inform DER
0:d=0 hl=2 l= 21 prim: cont [ 23 ]
Error in encoding
001EBA93B67F0000:error:0680007B:asn1 encoding routines:ASN1_get_object:header too long:crypto/asn1/asn1_lib.c:105:

which would suggest that it isn't X.509.

David