drivers/block/drbd/drbd_nla.c

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