block/drbd/drbd_nla.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 #include <linux/kernel.h>
0003 #include <net/netlink.h>
0004 #include <linux/drbd_genl_api.h>
0005 #include "drbd_nla.h"
0006
0007 static int drbd_nla_check_mandatory(int maxtype, struct nlattr *nla)
0008 {
0009     struct nlattr *head = nla_data(nla);
0010     int len = nla_len(nla);
0011     int rem;
0012
0013     /*
0014      * validate_nla (called from nla_parse_nested) ignores attributes
0015      * beyond maxtype, and does not understand the DRBD_GENLA_F_MANDATORY flag.
0016      * In order to have it validate attributes with the DRBD_GENLA_F_MANDATORY
0017      * flag set also, check and remove that flag before calling
0018      * nla_parse_nested.
0019      */
0020
0021     nla_for_each_attr(nla, head, len, rem) {
0022         if (nla->nla_type & DRBD_GENLA_F_MANDATORY) {
0023             nla->nla_type &= ~DRBD_GENLA_F_MANDATORY;
0024             if (nla_type(nla) > maxtype)
0025                 return -EOPNOTSUPP;
0026         }
0027     }
0028     return 0;
0029 }
0030
0031 int drbd_nla_parse_nested(struct nlattr *tb[], int maxtype, struct nlattr *nla,
0032               const struct nla_policy *policy)
0033 {
0034     int err;
0035
0036     err = drbd_nla_check_mandatory(maxtype, nla);
0037     if (!err)
0038         err = nla_parse_nested_deprecated(tb, maxtype, nla, policy,
0039                           NULL);
0040
0041     return err;
0042 }
0043
0044 struct nlattr *drbd_nla_find_nested(int maxtype, struct nlattr *nla, int attrtype)
0045 {
0046     int err;
0047     /*
0048      * If any nested attribute has the DRBD_GENLA_F_MANDATORY flag set and
0049      * we don't know about that attribute, reject all the nested
0050      * attributes.
0051      */
0052     err = drbd_nla_check_mandatory(maxtype, nla);
0053     if (err)
0054         return ERR_PTR(err);
0055     return nla_find_nested(nla, attrtype);
0056 }