From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Andy Lutomirski Subject: [ 34/42] userns: Changing any namespace id mappings should require privileges Date: Tue, 23 Apr 2013 14:52:32 -0700 Message-Id: <20130423215208.947820089@linuxfoundation.org> In-Reply-To: <20130423215205.523980967@linuxfoundation.org> References: <20130423215205.523980967@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.8-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andy Lutomirski commit 41c21e351e79004dbb4efa4bc14a53a7e0af38c5 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- kernel/user_namespace.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -576,10 +576,10 @@ static ssize_t map_write(struct file *fi 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 */