drivers/block/drbd/drbd_nla.c

   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
   7 static 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
  31 int 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
  43 struct 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 }