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    SubjectRe: [PATCH 2/4] X.509: Parse Basic Constraints for CA
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    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 <eric.snowberg@oracle.com>
    > ---
    > 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;
    > };

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