From: Vivek Goyal <vgoyal@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: virtio-fs@redhat.com, marcandre.lureau@redhat.com,
mst@redhat.com,
"Dr. David Alan Gilbert \(git\)" <dgilbert@redhat.com>,
qemu-devel@nongnu.org
Subject: Re: [PATCH 23/24] vhost-user-fs: Implement drop CAP_FSETID functionality
Date: Tue, 16 Feb 2021 10:57:10 -0500 [thread overview]
Message-ID: <20210216155710.GB10195@redhat.com> (raw)
In-Reply-To: <20210215155711.GA95852@stefanha-x1.localdomain>
On Mon, Feb 15, 2021 at 03:57:11PM +0000, Stefan Hajnoczi wrote:
> On Thu, Feb 11, 2021 at 09:40:31AM -0500, Vivek Goyal wrote:
> > On Thu, Feb 11, 2021 at 02:35:42PM +0000, Stefan Hajnoczi wrote:
> > > On Tue, Feb 09, 2021 at 07:02:23PM +0000, Dr. David Alan Gilbert (git) wrote:
> > > > From: Vivek Goyal <vgoyal@redhat.com>
> > > >
> > > > As part of slave_io message, slave can ask to do I/O on an fd. Additionally
> > > > slave can ask for dropping CAP_FSETID (if master has it) before doing I/O.
> > > > Implement functionality to drop CAP_FSETID and gain it back after the
> > > > operation.
> > > >
> > > > This also creates a dependency on libcap-ng.
> > >
> > > Is this patch only for the case where QEMU is running as root?
> > >
> >
> > Yes, it primarily is for the case where qemu is running as root, or
> > somebody managed to launch it non-root but with still having capability
> > CAP_FSETID.
>
> Running QEMU as root is not encouraged because the security model is
> designed around the principle of least privilege (only give QEMU access
> to resources that belong to the guest).
>
> What happens in the case where QEMU is not root? Does that mean QEMU
> will drop suid/guid bits even if the FUSE client wanted them to be
> preserved?
QEMU will drop CAP_FSETID only if vhost-user slave asked for it. There
is no notion of gaining CAP_FSETID.
IOW, yes, if qemu is running unpriviliged and does not have CAP_FSETID,
then we will end up clearing setuid bit on host. Not sure how that
problem can be fixed.
Vivek
WARNING: multiple messages have this Message-ID (diff)
From: Vivek Goyal <vgoyal@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: virtio-fs@redhat.com, marcandre.lureau@redhat.com,
mst@redhat.com, qemu-devel@nongnu.org
Subject: Re: [Virtio-fs] [PATCH 23/24] vhost-user-fs: Implement drop CAP_FSETID functionality
Date: Tue, 16 Feb 2021 10:57:10 -0500 [thread overview]
Message-ID: <20210216155710.GB10195@redhat.com> (raw)
In-Reply-To: <20210215155711.GA95852@stefanha-x1.localdomain>
On Mon, Feb 15, 2021 at 03:57:11PM +0000, Stefan Hajnoczi wrote:
> On Thu, Feb 11, 2021 at 09:40:31AM -0500, Vivek Goyal wrote:
> > On Thu, Feb 11, 2021 at 02:35:42PM +0000, Stefan Hajnoczi wrote:
> > > On Tue, Feb 09, 2021 at 07:02:23PM +0000, Dr. David Alan Gilbert (git) wrote:
> > > > From: Vivek Goyal <vgoyal@redhat.com>
> > > >
> > > > As part of slave_io message, slave can ask to do I/O on an fd. Additionally
> > > > slave can ask for dropping CAP_FSETID (if master has it) before doing I/O.
> > > > Implement functionality to drop CAP_FSETID and gain it back after the
> > > > operation.
> > > >
> > > > This also creates a dependency on libcap-ng.
> > >
> > > Is this patch only for the case where QEMU is running as root?
> > >
> >
> > Yes, it primarily is for the case where qemu is running as root, or
> > somebody managed to launch it non-root but with still having capability
> > CAP_FSETID.
>
> Running QEMU as root is not encouraged because the security model is
> designed around the principle of least privilege (only give QEMU access
> to resources that belong to the guest).
>
> What happens in the case where QEMU is not root? Does that mean QEMU
> will drop suid/guid bits even if the FUSE client wanted them to be
> preserved?
QEMU will drop CAP_FSETID only if vhost-user slave asked for it. There
is no notion of gaining CAP_FSETID.
IOW, yes, if qemu is running unpriviliged and does not have CAP_FSETID,
then we will end up clearing setuid bit on host. Not sure how that
problem can be fixed.
Vivek
next prev parent reply other threads:[~2021-02-16 15:58 UTC|newest]
Thread overview: 138+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-09 19:02 [PATCH 00/24] virtiofs dax patches Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [PATCH 01/24] DAX: vhost-user: Rework slave return values Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 9:59 ` Stefan Hajnoczi
2021-02-11 9:59 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-11 15:27 ` Vivek Goyal
2021-02-11 15:27 ` [Virtio-fs] " Vivek Goyal
2021-02-18 12:18 ` Dr. David Alan Gilbert
2021-02-18 12:18 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-02-09 19:02 ` [PATCH 02/24] DAX: libvhost-user: Route slave message payload Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 10:05 ` Stefan Hajnoczi
2021-02-11 10:05 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 03/24] DAX: libvhost-user: Allow popping a queue element with bad pointers Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 10:12 ` Stefan Hajnoczi
2021-02-11 10:12 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 04/24] DAX subprojects/libvhost-user: Add virtio-fs slave types Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 10:16 ` Stefan Hajnoczi
2021-02-11 10:16 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 05/24] DAX: virtio: Add shared memory capability Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 10:17 ` Stefan Hajnoczi
2021-02-11 10:17 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 06/24] DAX: virtio-fs: Add cache BAR Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 10:25 ` Stefan Hajnoczi
2021-02-11 10:25 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-18 17:33 ` Dr. David Alan Gilbert
2021-02-18 17:33 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-02-09 19:02 ` [PATCH 07/24] DAX: virtio-fs: Add vhost-user slave commands for mapping Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 10:32 ` Stefan Hajnoczi
2021-02-11 10:32 ` [Virtio-fs] " Stefan Hajnoczi
2021-03-08 17:04 ` Dr. David Alan Gilbert
2021-03-08 17:04 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-02-15 10:35 ` Chirantan Ekbote
2021-02-15 10:35 ` Chirantan Ekbote
2021-02-15 13:25 ` Dr. David Alan Gilbert
2021-02-15 13:25 ` Dr. David Alan Gilbert
2021-02-15 14:24 ` Vivek Goyal
2021-02-15 14:24 ` Vivek Goyal
2021-03-11 12:15 ` Dr. David Alan Gilbert
2021-03-11 12:15 ` Dr. David Alan Gilbert
2021-03-11 13:50 ` Vivek Goyal
2021-03-11 13:50 ` Vivek Goyal
2021-03-11 18:52 ` Dr. David Alan Gilbert
2021-03-11 18:52 ` Dr. David Alan Gilbert
2021-02-09 19:02 ` [PATCH 08/24] DAX: virtio-fs: Fill in " Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 10:57 ` Stefan Hajnoczi
2021-02-11 10:57 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-18 10:59 ` Dr. David Alan Gilbert
2021-02-18 10:59 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-02-09 19:02 ` [PATCH 09/24] DAX: virtiofsd Add cache accessor functions Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 12:31 ` Stefan Hajnoczi
2021-02-11 12:31 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 10/24] DAX: virtiofsd: Add setup/remove mappings fuse commands Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 12:37 ` Stefan Hajnoczi
2021-02-11 12:37 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-11 16:39 ` Dr. David Alan Gilbert
2021-02-11 16:39 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-02-11 18:30 ` Vivek Goyal
2021-02-11 18:30 ` [Virtio-fs] " Vivek Goyal
2021-02-11 19:50 ` Dr. David Alan Gilbert
2021-02-11 19:50 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-02-11 20:15 ` Vivek Goyal
2021-02-11 20:15 ` [Virtio-fs] " Vivek Goyal
2021-02-09 19:02 ` [PATCH 11/24] DAX: virtiofsd: Add setup/remove mapping handlers to passthrough_ll Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 12:37 ` Stefan Hajnoczi
2021-02-11 12:37 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 12/24] DAX: virtiofsd: Wire up passthrough_ll's lo_setupmapping Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 12:41 ` Stefan Hajnoczi
2021-02-11 12:41 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-11 16:05 ` Vivek Goyal
2021-02-11 16:05 ` [Virtio-fs] " Vivek Goyal
2021-02-09 19:02 ` [PATCH 13/24] DAX: virtiofsd: Make lo_removemapping() work Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 12:41 ` Stefan Hajnoczi
2021-02-11 12:41 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 14/24] DAX: virtiofsd: route se down to destroy method Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 12:42 ` Stefan Hajnoczi
2021-02-11 12:42 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 15/24] DAX: virtiofsd: Perform an unmap on destroy Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 12:42 ` Stefan Hajnoczi
2021-02-11 12:42 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 16/24] DAX/unmap: virtiofsd: Add VHOST_USER_SLAVE_FS_IO Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 14:17 ` Stefan Hajnoczi
2021-02-11 14:17 ` [Virtio-fs] " Stefan Hajnoczi
2021-03-16 19:59 ` Dr. David Alan Gilbert
2021-03-16 19:59 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-03-31 10:12 ` Stefan Hajnoczi
2021-03-31 10:12 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 17/24] DAX/unmap virtiofsd: Add wrappers for VHOST_USER_SLAVE_FS_IO Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 14:18 ` Stefan Hajnoczi
2021-02-11 14:18 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 18/24] DAX/unmap virtiofsd: Parse unmappable elements Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 14:29 ` Stefan Hajnoczi
2021-02-11 14:29 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-25 10:19 ` Dr. David Alan Gilbert
2021-02-25 10:19 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-03-31 10:14 ` Stefan Hajnoczi
2021-03-31 10:14 ` [Virtio-fs] " Stefan Hajnoczi
2021-03-17 10:33 ` Dr. David Alan Gilbert
2021-03-17 10:33 ` [Virtio-fs] " Dr. David Alan Gilbert
2021-02-09 19:02 ` [PATCH 19/24] DAX/unmap virtiofsd: Route unmappable reads Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [PATCH 20/24] DAX/unmap virtiofsd: route unmappable write to slave command Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [PATCH 21/24] DAX:virtiofsd: implement FUSE_INIT map_alignment field Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [PATCH 22/24] vhost-user-fs: Extend VhostUserFSSlaveMsg to pass additional info Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [PATCH 23/24] vhost-user-fs: Implement drop CAP_FSETID functionality Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
2021-02-11 14:35 ` Stefan Hajnoczi
2021-02-11 14:35 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-11 14:40 ` Vivek Goyal
2021-02-11 14:40 ` [Virtio-fs] " Vivek Goyal
2021-02-15 15:57 ` Stefan Hajnoczi
2021-02-15 15:57 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-16 15:57 ` Vivek Goyal [this message]
2021-02-16 15:57 ` Vivek Goyal
2021-02-22 16:53 ` Stefan Hajnoczi
2021-02-22 16:53 ` [Virtio-fs] " Stefan Hajnoczi
2021-02-09 19:02 ` [PATCH 24/24] virtiofsd: Ask qemu to drop CAP_FSETID if client asked for it Dr. David Alan Gilbert (git)
2021-02-09 19:02 ` [Virtio-fs] " Dr. David Alan Gilbert (git)
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