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Diffstat (limited to 'drivers/block/drbd/drbd_nla.c')
-rw-r--r--drivers/block/drbd/drbd_nla.c56
1 files changed, 56 insertions, 0 deletions
diff --git a/drivers/block/drbd/drbd_nla.c b/drivers/block/drbd/drbd_nla.c
new file mode 100644
index 0000000000..df0d241d3f
--- /dev/null
+++ b/drivers/block/drbd/drbd_nla.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/kernel.h>
+#include <net/netlink.h>
+#include <linux/drbd_genl_api.h>
+#include "drbd_nla.h"
+
+static int drbd_nla_check_mandatory(int maxtype, struct nlattr *nla)
+{
+ struct nlattr *head = nla_data(nla);
+ int len = nla_len(nla);
+ int rem;
+
+ /*
+ * validate_nla (called from nla_parse_nested) ignores attributes
+ * beyond maxtype, and does not understand the DRBD_GENLA_F_MANDATORY flag.
+ * In order to have it validate attributes with the DRBD_GENLA_F_MANDATORY
+ * flag set also, check and remove that flag before calling
+ * nla_parse_nested.
+ */
+
+ nla_for_each_attr(nla, head, len, rem) {
+ if (nla->nla_type & DRBD_GENLA_F_MANDATORY) {
+ nla->nla_type &= ~DRBD_GENLA_F_MANDATORY;
+ if (nla_type(nla) > maxtype)
+ return -EOPNOTSUPP;
+ }
+ }
+ return 0;
+}
+
+int drbd_nla_parse_nested(struct nlattr *tb[], int maxtype, struct nlattr *nla,
+ const struct nla_policy *policy)
+{
+ int err;
+
+ err = drbd_nla_check_mandatory(maxtype, nla);
+ if (!err)
+ err = nla_parse_nested_deprecated(tb, maxtype, nla, policy,
+ NULL);
+
+ return err;
+}
+
+struct nlattr *drbd_nla_find_nested(int maxtype, struct nlattr *nla, int attrtype)
+{
+ int err;
+ /*
+ * If any nested attribute has the DRBD_GENLA_F_MANDATORY flag set and
+ * we don't know about that attribute, reject all the nested
+ * attributes.
+ */
+ err = drbd_nla_check_mandatory(maxtype, nla);
+ if (err)
+ return ERR_PTR(err);
+ return nla_find_nested(nla, attrtype);
+}