From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 792C021265793 for ; Tue, 21 May 2019 08:01:34 -0700 (PDT) Date: Tue, 21 May 2019 11:01:31 -0400 From: Vivek Goyal Subject: Re: [PATCH v2 02/30] fuse: Clear setuid bit even in cache=never path Message-ID: <20190521150131.GB29075@redhat.com> References: <20190515192715.18000-1-vgoyal@redhat.com> <20190515192715.18000-3-vgoyal@redhat.com> <20190520144137.GA24093@localhost.localdomain> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190520144137.GA24093@localhost.localdomain> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Miklos Szeredi Cc: kvm@vger.kernel.org, linux-nvdimm@lists.01.org, dgilbert@redhat.com, linux-kernel@vger.kernel.org, stefanha@redhat.com, linux-fsdevel@vger.kernel.org, swhiteho@redhat.com List-ID: On Mon, May 20, 2019 at 04:41:37PM +0200, Miklos Szeredi wrote: > On Wed, May 15, 2019 at 03:26:47PM -0400, Vivek Goyal wrote: > > If fuse daemon is started with cache=never, fuse falls back to direct IO. > > In that write path we don't call file_remove_privs() and that means setuid > > bit is not cleared if unpriviliged user writes to a file with setuid bit set. > > > > pjdfstest chmod test 12.t tests this and fails. > > I think better sulution is to tell the server if the suid bit needs to be > removed, so it can do so in a race free way. > > Here's the kernel patch, and I'll reply with the libfuse patch. Hi Miklos, I tested and it works for me. Vivek > > --- > fs/fuse2/file.c | 2 ++ > include/uapi/linux/fuse.h | 3 +++ > 2 files changed, 5 insertions(+) > > --- a/fs/fuse2/file.c > +++ b/fs/fuse2/file.c > @@ -363,6 +363,8 @@ static ssize_t fuse_send_write(struct fu > inarg->flags |= O_DSYNC; > if (iocb->ki_flags & IOCB_SYNC) > inarg->flags |= O_SYNC; > + if (!capable(CAP_FSETID)) > + inarg->write_flags |= FUSE_WRITE_KILL_PRIV; > req->inh.opcode = FUSE_WRITE; > req->inh.nodeid = ff->nodeid; > req->inh.len = req->inline_inlen + count; > --- a/include/uapi/linux/fuse.h > +++ b/include/uapi/linux/fuse.h > @@ -125,6 +125,7 @@ > * > * 7.29 > * - add FUSE_NO_OPENDIR_SUPPORT flag > + * - add FUSE_WRITE_KILL_PRIV flag > */ > > #ifndef _LINUX_FUSE_H > @@ -318,9 +319,11 @@ struct fuse_file_lock { > * > * FUSE_WRITE_CACHE: delayed write from page cache, file handle is guessed > * FUSE_WRITE_LOCKOWNER: lock_owner field is valid > + * FUSE_WRITE_KILL_PRIV: kill suid and sgid bits > */ > #define FUSE_WRITE_CACHE (1 << 0) > #define FUSE_WRITE_LOCKOWNER (1 << 1) > +#define FUSE_WRITE_KILL_PRIV (1 << 2) > > /** > * Read flags > > _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm