Messages in this thread | | | Date | Tue, 8 Mar 2022 08:56:57 -0500 | Subject | Re: [PATCH 3/4] KEYS: CA link restriction | From | Stefan Berger <> |
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On 3/8/22 07:45, Mimi Zohar wrote: > On Mon, 2022-03-07 at 21:31 -0500, Stefan Berger wrote: >> >> On 3/7/22 18:38, Eric Snowberg wrote: >>> >>> >>>> On Mar 7, 2022, at 4:01 PM, Mimi Zohar <zohar@linux.ibm.com> wrote: >>>> >>>> On Mon, 2022-03-07 at 18:06 +0000, Eric Snowberg wrote: >>>>> >>>>>>> diff --git a/crypto/asymmetric_keys/restrict.c b/crypto/asymmetric_keys/restrict.c >>>>>>> index 6b1ac5f5896a..49bb2ea7f609 100644 >>>>>>> --- a/crypto/asymmetric_keys/restrict.c >>>>>>> +++ b/crypto/asymmetric_keys/restrict.c >>>>>>> @@ -108,6 +108,49 @@ int restrict_link_by_signature(struct key *dest_keyring, >>>>>>> return ret; >>>>>>> } >>>>>>> +/** >>>>>>> + * restrict_link_by_ca - Restrict additions to a ring of CA keys >>>>>>> + * @dest_keyring: Keyring being linked to. >>>>>>> + * @type: The type of key being added. >>>>>>> + * @payload: The payload of the new key. >>>>>>> + * @trust_keyring: Unused. >>>>>>> + * >>>>>>> + * Check if the new certificate is a CA. If it is a CA, then mark the new >>>>>>> + * certificate as being ok to link. >>>>>> >>>>>> CA = root CA here, right? >>>>> >>>>> Yes, I’ll update the comment >>>> >>>> Updating the comment is not enough. There's an existing function named >>>> "x509_check_for_self_signed()" which determines whether the certificate >>>> is self-signed. >>> >>> Originally I tried using that function. However when the restrict link code is called, >>> all the necessary x509 information is no longer available. The code in >>> restrict_link_by_ca is basically doing the equivalent to x509_check_for_self_signed. >>> After verifying the cert has the CA flag set, the call to public_key_verify_signature >>> validates the cert is self signed. >>> >> Isn't x509_cert_parse() being called as part of parsing the certificate? >> If so, it seems to check for a self-signed certificate every time. You >> could add something like the following to x509_check_for_self_signed(cert): >> pub->x509_self_signed = cert->self_signed = true; >> >> This could then reduce the function in 3/4 to something like: >> >> return payload->data[asym_crypto]->x509_self_signed; > > Agreed, as long as the other two criteria are also met: CA and keyUsage > should be required and limited to keyCertSign.
right, it's not as easy as the return statement above...
> > thanks, > > Mimi >
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