1// SPDX-License-Identifier: GPL-2.0
 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(tb, maxtype, nla, policy, NULL);
39
40	return err;
41}
42
43struct nlattr *drbd_nla_find_nested(int maxtype, struct nlattr *nla, int attrtype)
44{
45	int err;
46	/*
47	 * If any nested attribute has the DRBD_GENLA_F_MANDATORY flag set and
48	 * we don't know about that attribute, reject all the nested
49	 * attributes.
50	 */
51	err = drbd_nla_check_mandatory(maxtype, nla);
52	if (err)
53		return ERR_PTR(err);
54	return nla_find_nested(nla, attrtype);
55}