--- /dev/null
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <pwd.h>
+#include <grp.h>
+#include <keyutils.h>
+#include <nfsidmap.h>
+
+#include <syslog.h>
+
+/* gcc nfsidmap.c -o nfsidmap -l nfsidmap -l keyutils */
+
+#define MAX_ID_LEN 11
+#define IDMAP_NAMESZ 128
+#define USER 1
+#define GROUP 0
+
+
+/*
+ * Find either a user or group id based on the name@domain string
+ */
+int id_lookup(char *name_at_domain, key_serial_t key, int type)
+{
+ char id[MAX_ID_LEN];
+ uid_t uid = 0;
+ gid_t gid = 0;
+ int rc;
+
+ if (type == USER) {
+ rc = nfs4_owner_to_uid(name_at_domain, &uid);
+ sprintf(id, "%u", uid);
+ } else {
+ rc = nfs4_group_owner_to_gid(name_at_domain, &gid);
+ sprintf(id, "%u", gid);
+ }
+
+ if (rc == 0)
+ rc = keyctl_instantiate(key, id, strlen(id) + 1, 0);
+
+ return rc;
+}
+
+/*
+ * Find the name@domain string from either a user or group id
+ */
+int name_lookup(char *id, key_serial_t key, int type)
+{
+ char name[IDMAP_NAMESZ];
+ char domain[NFS4_MAX_DOMAIN_LEN];
+ uid_t uid;
+ gid_t gid;
+ int rc;
+
+ rc = nfs4_get_default_domain(NULL, domain, NFS4_MAX_DOMAIN_LEN);
+ if (rc != 0) {
+ rc = -1;
+ goto out;
+ }
+
+ if (type == USER) {
+ uid = atoi(id);
+ rc = nfs4_uid_to_name(uid, domain, name, IDMAP_NAMESZ);
+ } else {
+ gid = atoi(id);
+ rc = nfs4_gid_to_name(gid, domain, name, IDMAP_NAMESZ);
+ }
+
+ if (rc == 0)
+ rc = keyctl_instantiate(key, &name, strlen(name), 0);
+
+out:
+ return rc;
+}
+
+int main(int argc, char **argv)
+{
+ char *arg;
+ char *value;
+ char *type;
+ int rc = 1;
+ int timeout = 600;
+ key_serial_t key;
+
+ if (argc < 3)
+ return 1;
+
+ arg = malloc(sizeof(char) * strlen(argv[2]) + 1);
+ strcpy(arg, argv[2]);
+ type = strtok(arg, ":");
+ value = strtok(NULL, ":");
+
+ if (argc == 4) {
+ timeout = atoi(argv[3]);
+ if (timeout < 0)
+ timeout = 0;
+ }
+
+ key = strtol(argv[1], NULL, 10);
+
+ if (strcmp(type, "uid") == 0)
+ rc = id_lookup(value, key, USER);
+ else if (strcmp(type, "gid") == 0)
+ rc = id_lookup(value, key, GROUP);
+ else if (strcmp(type, "user") == 0)
+ rc = name_lookup(value, key, USER);
+ else if (strcmp(type, "group") == 0)
+ rc = name_lookup(value, key, GROUP);
+
+ /* Set timeout to 5 (600 seconds) minutes */
+ if (rc == 0)
+ keyctl_set_timeout(key, timeout);
+
+ free(arg);
+ return rc;
+}