userns: save uid-s from a target userns (v2)

We are going to support user namespaces and uid-s will be converted
accoding with userns mappings.

v2: conver id-s for sockets too
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

files-reg.c

@@ -324,8 +324,8 @@ static int dump_ghost_file(int _fd, u32 id, const struct stat *st, dev_t phys_de
 	if (img < 0)
 		return -1;
 
-	gfe.uid = st->st_uid;
-	gfe.gid = st->st_gid;
+	gfe.uid = userns_uid(st->st_uid);
+	gfe.gid = userns_gid(st->st_gid);
 	gfe.mode = st->st_mode;
 
 	gfe.has_dev = gfe.has_ino = true;

include/namespaces.h

@@ -63,4 +63,7 @@ extern struct ns_id *rst_new_ns_id(unsigned int id, pid_t pid, struct ns_desc *n
 extern int rst_add_ns_id(unsigned int id, pid_t pid, struct ns_desc *nd);
 extern struct ns_id *lookup_ns_by_id(unsigned int id, struct ns_desc *nd);
 
+extern int userns_uid(int uid);
+extern int userns_gid(int gid);
+
 #endif /* __CR_NS_H__ */

namespaces.c

@@ -477,6 +477,21 @@ int dump_task_ns_ids(struct pstree_item *item)
 	return 0;
 }
 
+static int userns_id(int id)
+{
+	return id;
+}
+
+int userns_uid(int uid)
+{
+	return userns_id(uid);
+}
+
+int userns_gid(int gid)
+{
+	return userns_id(gid);
+}
+
 static int dump_user_ns(pid_t pid, int ns_id)
 {
 	pr_err("User namesapces are not supported yet\n");

sk-unix.c

@@ -209,8 +209,8 @@ static int dump_one_unix_fd(int lfd, u32 id, const struct fd_parms *p)
 		ue->file_perms = perms;
 
 		perms->mode	= sk->mode;
-		perms->uid	= sk->uid;
-		perms->gid	= sk->gid;
+		perms->uid	= userns_uid(sk->uid);
+		perms->gid	= userns_gid(sk->gid);
 	}
 
 	sk_encode_shutdown(ue, sk->shutdown);