1// SPDX-License-Identifier: GPL-2.0-only
2#include <linux/kernel.h>
3#include <net/netlink.h>
4#include <linux/drbd_genl_api.h>
5#include "drbd_nla.h"
6
7static int drbd_nla_check_mandatory(int maxtype, struct nlattr *nla)
8{
9	struct nlattr *head = nla_data(nla);
10	int len = nla_len(nla);
11	int rem;
12
13	/*
14	 * validate_nla (called from nla_parse_nested) ignores attributes
15	 * beyond maxtype, and does not understand the DRBD_GENLA_F_MANDATORY flag.
16	 * In order to have it validate attributes with the DRBD_GENLA_F_MANDATORY
17	 * flag set also, check and remove that flag before calling
18	 * nla_parse_nested.
19	 */
20
21	nla_for_each_attr(nla, head, len, rem) {
22		if (nla->nla_type & DRBD_GENLA_F_MANDATORY) {
23			nla->nla_type &= ~DRBD_GENLA_F_MANDATORY;
24			if (nla_type(nla) > maxtype)
25				return -EOPNOTSUPP;
26		}
27	}
28	return 0;
29}
30
31int drbd_nla_parse_nested(struct nlattr *tb[], int maxtype, struct nlattr *nla,
32			  const struct nla_policy *policy)
33{
34	int err;
35
36	err = drbd_nla_check_mandatory(maxtype, nla);
37	if (!err)
38		err = nla_parse_nested_deprecated(tb, maxtype, nla, policy,
39						  NULL);
40
41	return err;
42}
43
44struct nlattr *drbd_nla_find_nested(int maxtype, struct nlattr *nla, int attrtype)
45{
46	int err;
47	/*
48	 * If any nested attribute has the DRBD_GENLA_F_MANDATORY flag set and
49	 * we don't know about that attribute, reject all the nested
50	 * attributes.
51	 */
52	err = drbd_nla_check_mandatory(maxtype, nla);
53	if (err)
54		return ERR_PTR(err);
55	return nla_find_nested(nla, attrtype);
56}
57