Is this a bug in openssl provider?

[Afshin Pir]

Hi

Since I'm writing a small provider, I'm reading openssl provider source to use as learning tool. Today, I noticed something strange in RSA key management here: https://github.com/openssl/openssl/blob/3307338e26862070eaacad6ec7537a63a63b8a90/providers/implementations/keymgmt/rsa_kmgmt.c#L115-L133

The rsa_has() method is written like this:
static int rsa_has(const void *keydata, int selection)
{
    const RSA *rsa = keydata;
    int ok = 1;

    if (rsa == NULL || !ossl_prov_is_running())
        return 0;
    if ((selection & RSA_POSSIBLE_SELECTIONS) == 0)
        return 1; /* the selection is not missing */

    /* OSSL_KEYMGMT_SELECT_OTHER_PARAMETERS are always available even if empty */
    if ((selection & OSSL_KEYMGMT_SELECT_KEYPAIR) != 0)
        ok = ok && (RSA_get0_e(rsa) != NULL);
    if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0)
        ok = ok && (RSA_get0_n(rsa) != NULL);
    if ((selection & OSSL_KEYMGMT_SELECT_PRIVATE_KEY) != 0)
        ok = ok && (RSA_get0_d(rsa) != NULL);
    return ok;
}

But I think selection of OSSL_KEYMGMT_SELECT_KEYPAIR and OSSL_KEYMGMT_SELECT_PUBLIC_KEY should be like this:
    if ((selection & OSSL_KEYMGMT_SELECT_KEYPAIR) != 0)
        ok = ok && (RSA_get0_n(rsa) != NULL);
    if ((selection & OSSL_KEYMGMT_SELECT_PUBLIC_KEY) != 0)
        ok = ok && (RSA_get0_e(rsa) != NULL);
RSA public key is pair (e,n) and private key is (d,n). `n` is the common part, so I think in case of OSSL_KEYMGMT_SELECT_KEYPAIR, we need to check `n` is not null, not `e` and we need to check `e` for public key. Current rsa_has() return 1 if RSA structure has `d` and `e` but no `n` and we OSSL_KEYMGMT_SELECT_PRIVATE_KEY selection which I think is incorrect.

What do you think? Do you think it is a bug too?
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