// SPDX-License-Identifier: GPL-2.0-only
#include <linux/kernel.h>
#include <net/netlink.h>
#include <linux/drbd_genl_api.h>
#include "drbd_nla.h"

static int drbd_nla_check_mandatory(int maxtype, struct nlattr *nla)
{
        struct nlattr *head = nla_data(nla);
        int len = nla_len(nla);
        int rem;

        /*
         * validate_nla (called from nla_parse_nested) ignores attributes
         * beyond maxtype, and does not understand the DRBD_GENLA_F_MANDATORY flag.
         * In order to have it validate attributes with the DRBD_GENLA_F_MANDATORY
         * flag set also, check and remove that flag before calling
         * nla_parse_nested.
         */

        nla_for_each_attr(nla, head, len, rem) {
                if (nla->nla_type & DRBD_GENLA_F_MANDATORY) {
                        nla->nla_type &= ~DRBD_GENLA_F_MANDATORY;
                        if (nla_type(nla) > maxtype)
                                return -EOPNOTSUPP;
                }
        }
        return 0;
}

int drbd_nla_parse_nested(struct nlattr *tb[], int maxtype, struct nlattr *nla,
                          const struct nla_policy *policy)
{
        int err;

        err = drbd_nla_check_mandatory(maxtype, nla);
        if (!err)
                err = nla_parse_nested_deprecated(tb, maxtype, nla, policy,
                                                  NULL);

        return err;
}

struct nlattr *drbd_nla_find_nested(int maxtype, struct nlattr *nla, int attrtype)
{
        int err;
        /*
         * If any nested attribute has the DRBD_GENLA_F_MANDATORY flag set and
         * we don't know about that attribute, reject all the nested
         * attributes.
         */
        err = drbd_nla_check_mandatory(maxtype, nla);
        if (err)
                return ERR_PTR(err);
        return nla_find_nested(nla, attrtype);
}