On 3/1/22 12:36, 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 <[email protected]>
> ---
> 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 2899ed80bb18..38c907f4ce27 100644
> --- a/crypto/asymmetric_keys/x509_cert_parser.c
> +++ b/crypto/asymmetric_keys/x509_cert_parser.c
> @@ -583,6 +583,15 @@ int x509_process_extension(void *context, size_t hdrlen,
> return 0;
> }
>
> + if (ctx->last_oid == OID_basicConstraints) {
Don't you have to check whether you can access v[0] and v[1]?
if (vlen < 3)
return -EBADMSG;
or should it even be
if (vlen != 3)
return -EBADMSG;
> + 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 6d61695e1cde..0521241764b7 100644
> --- a/include/crypto/public_key.h
> +++ b/include/crypto/public_key.h
> @@ -26,6 +26,7 @@ struct public_key {
> void *params;
> u32 paramlen;
> bool key_is_private;
> + bool key_is_ca;
> const char *id_type;
> const char *pkey_algo;
> };