From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1034500AbeEXTMj (ORCPT ); Thu, 24 May 2018 15:12:39 -0400 Received: from mx2.mailbox.org ([80.241.60.215]:39160 "EHLO mx2.mailbox.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1034448AbeEXTMh (ORCPT ); Thu, 24 May 2018 15:12:37 -0400 Date: Thu, 24 May 2018 21:12:32 +0200 From: Christian Brauner To: "Eric W. Biederman" Cc: Linux Containers , linux-fsdevel@vger.kernel.org, Seth Forshee , "Serge E. Hallyn" , linux-kernel@vger.kernel.org Subject: Re: [REVIEW][PATCH 2/6] vfs: Allow userns root to call mknod on owned filesystems. Message-ID: <20180524191232.GA7573@mailbox.org> References: <87o9h6554f.fsf@xmission.com> <20180523232538.4880-2-ebiederm@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180523232538.4880-2-ebiederm@xmission.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 23, 2018 at 06:25:34PM -0500, Eric W. Biederman wrote: > These filesystems already always set SB_I_NODEV so mknod will not be > useful for gaining control of any devices no matter their permissions. > This will allow overlayfs and applications to fakeroot to use device > nodes to represent things on disk. Excellent. Acked-by: Christian Brauner > > Signed-off-by: "Eric W. Biederman" > --- > fs/namei.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/namei.c b/fs/namei.c > index 942c1f096f6b..20335896dcce 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -3679,7 +3679,8 @@ int vfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev) > if (error) > return error; > > - if ((S_ISCHR(mode) || S_ISBLK(mode)) && !capable(CAP_MKNOD)) > + if ((S_ISCHR(mode) || S_ISBLK(mode)) && > + !ns_capable(dentry->d_sb->s_user_ns, CAP_MKNOD)) > return -EPERM; > > if (!dir->i_op->mknod) > -- > 2.14.1 >