/* Provenance: openssl/openssl check_policy (fixed).
 * repo: openssl/openssl
 * commit: b013765abfa80036dc779dd0e50602c57bb3bf95
 * parent: f675d164e5d9648c3537a0f5efe1cc2fd232b4a9
 * commit_url: https://github.com/openssl/openssl/commit/b013765abfa80036dc779dd0e50602c57bb3bf95
 * cve: CVE-2023-0465
 * license: Apache-2.0
 * function: check_policy
 * relpath: crypto/x509/x509_vfy.c
 */

static int check_policy(X509_STORE_CTX *ctx)
{
    int ret;

    if (ctx->parent)
        return 1;
    /*
     * With DANE, the trust anchor might be a bare public key, not a
     * certificate!  In that case our chain does not have the trust anchor
     * certificate as a top-most element.  This comports well with RFC5280
     * chain verification, since there too, the trust anchor is not part of the
     * chain to be verified.  In particular, X509_policy_check() does not look
     * at the TA cert, but assumes that it is present as the top-most chain
     * element.  We therefore temporarily push a NULL cert onto the chain if it
     * was verified via a bare public key, and pop it off right after the
     * X509_policy_check() call.
     */
    if (ctx->bare_ta_signed && !sk_X509_push(ctx->chain, NULL)) {
        X509err(X509_F_CHECK_POLICY, ERR_R_MALLOC_FAILURE);
        ctx->error = X509_V_ERR_OUT_OF_MEM;
        return 0;
    }
    ret = X509_policy_check(&ctx->tree, &ctx->explicit_policy, ctx->chain,
                            ctx->param->policies, ctx->param->flags);
    if (ctx->bare_ta_signed)
        sk_X509_pop(ctx->chain);

    if (ret == X509_PCY_TREE_INTERNAL) {
        X509err(X509_F_CHECK_POLICY, ERR_R_MALLOC_FAILURE);
        ctx->error = X509_V_ERR_OUT_OF_MEM;
        return 0;
    }
    /* Invalid or inconsistent extensions */
    if (ret == X509_PCY_TREE_INVALID) {
        int i, cbcalled = 0;

        /* Locate certificates with bad extensions and notify callback. */
        for (i = 0; i < sk_X509_num(ctx->chain); i++) {
            X509 *x = sk_X509_value(ctx->chain, i);

            if (!(x->ex_flags & EXFLAG_INVALID_POLICY))
                continue;
            cbcalled = 1;
            if (!verify_cb_cert(ctx, x, i,
                                X509_V_ERR_INVALID_POLICY_EXTENSION))
                return 0;
        }
        if (!cbcalled) {
            /* Should not be able to get here */
            X509err(X509_F_CHECK_POLICY, ERR_R_INTERNAL_ERROR);
            return 0;
        }
        /* The callback ignored the error so we return success */
        return 1;
    }
    if (ret == X509_PCY_TREE_FAILURE) {
        ctx->current_cert = NULL;
        ctx->error = X509_V_ERR_NO_EXPLICIT_POLICY;
        return ctx->verify_cb(0, ctx);
    }
    if (ret != X509_PCY_TREE_VALID) {
        X509err(X509_F_CHECK_POLICY, ERR_R_INTERNAL_ERROR);
        return 0;
    }

    if (ctx->param->flags & X509_V_FLAG_NOTIFY_POLICY) {
        ctx->current_cert = NULL;
        /*
         * Verification errors need to be "sticky", a callback may have allowed
         * an SSL handshake to continue despite an error, and we must then
         * remain in an error state.  Therefore, we MUST NOT clear earlier
         * verification errors by setting the error to X509_V_OK.
         */
        if (!ctx->verify_cb(2, ctx))
            return 0;
    }

    return 1;
}