Re: [Virtio-fs] [PATCH 2/2] virtiofsd: move to a new pid namespace

[Stefan Hajnoczi]

On Thu, Oct 17, 2019 at 10:45:53AM -0400, Vivek Goyal wrote:
> On Wed, Oct 16, 2019 at 05:01:57PM +0100, Stefan Hajnoczi wrote:
> 
> [..]
> > +   /*
> > +    * If the mounts have shared propagation then we want to opt out so our
> > +    * mount changes don't affect the parent mount namespace.
> > +    */
> > +   if (mount(NULL, "/", NULL, MS_REC|MS_SLAVE, NULL) < 0) {
> > +           fuse_log(FUSE_LOG_ERR, "mount(/, MS_REC|MS_SLAVE): %m\n");
> > +           exit(1);
> > +   }
> 
> So we will get mount propogation form parent but our mounts will not
> propagate back. Sounds reasonable.
> 
> Can we take away CAP_SYS_ADMIN from virtiofsd? That way it will not be 
> able to do mount at all. 
> 
> I am wondering are we dependent on daemon having CAP_SYS_ADMIN. 

I don't know the answer.  Additional patches to reduce the capability
set as much as possible would be great, but are a separate task.

Stefan

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