Commit 41c21e35 authored Apr 14, 2013 by Andy Lutomirski

userns: Changing any namespace id mappings should require privileges



Changing uid/gid/projid mappings doesn't change your id within the
namespace; it reconfigures the namespace.  Unprivileged programs should
*not* be able to write these files.  (We're also checking the privileges
on the wrong task.)

Given the write-once nature of these files and the other security
checks, this is likely impossible to usefully exploit.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>

parent e3211c12

kernel/user_namespace.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -613,10 +613,10 @@ static ssize_t map_write(struct file file, const char __user buf,
		if (map->nr_extents != 0)
		goto out;

		/* Require the appropriate privilege CAP_SETUID or CAP_SETGID
		* over the user namespace in order to set the id mapping.
		/*
		* Adjusting namespace settings requires capabilities on the target.
		*/
		if (cap_valid(cap_setid) && !ns_capable(ns, cap_setid))
		if (cap_valid(cap_setid) && !file_ns_capable(file, ns, CAP_SYS_ADMIN))
		goto out;

		/* Get a buffer */