Re: [PATCH v7 04/17] X.509: Parse Basic Constraints for CA

Eric Snowberg
2021-11-18T23:30:10Z

> On Nov 18, 2021, at 3:59 PM, Mimi Zohar <zohar@linux.ibm.com> wrote:
>
> Hi Eric,
>
> On Mon, 2021-11-15 at 19:15 -0500, Eric Snowberg wrote:
>> Parse the X.509 Basic Constraints. The basic constraints extension
>> identifies whether the subject of the certificate is a CA.
>>
>> BasicConstraints ::= SEQUENCE {
>> cA BOOLEAN DEFAULT FALSE,
>> pathLenConstraint INTEGER (0..MAX) OPTIONAL }
>>
>> If the CA is true, store it in a new public_key field call key_is_ca.
>> This will be used in a follow on patch that requires knowing if the
>> public key is a CA.
>>
>> Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
>> ---
>> v7: Initial version
>> ---
>> crypto/asymmetric_keys/x509_cert_parser.c | 9 +++++++++
>> include/crypto/public_key.h | 1 +
>> 2 files changed, 10 insertions(+)
>>
>> diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
>> index 6d003096b5bc..f4299b8a4926 100644
>> --- a/crypto/asymmetric_keys/x509_cert_parser.c
>> +++ b/crypto/asymmetric_keys/x509_cert_parser.c
>> @@ -571,6 +571,15 @@ int x509_process_extension(void *context, size_t hdrlen,
>> return 0;
>> }
>>
>> + if (ctx->last_oid == OID_basicConstraints) {
>> + if (v[0] != (ASN1_CONS_BIT | ASN1_SEQ))
>> + return -EBADMSG;
>> + if (v[1] != vlen - 2)
>> + return -EBADMSG;
>> + if (v[1] != 0 && v[2] == ASN1_BOOL && v[3] == 1)
>> + ctx->cert->pub->key_is_ca = true;
>> + }
>> +
>> return 0;
>> }
>>
>> diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
>> index a9b2e600b7cc..61c66be80995 100644
>> --- a/include/crypto/public_key.h
>> +++ b/include/crypto/public_key.h
>> @@ -28,6 +28,7 @@ struct public_key {
>> bool key_is_private;
>> const char *id_type;
>> const char *pkey_algo;
>> + bool key_is_ca;
>
> David added "key_is_private" intentionally where he did. Adding the
> "key_is_ca" immediately afterwards doesn't change the struct size.

Ok, I’ll change that in the next round. Thanks.