On Fri, 5 May 2017 12:11:14 -0500 Eric Blake <ebl...@redhat.com> wrote:
> On 05/05/2017 09:37 AM, Greg Kurz wrote: > > When using the mapped-file security, credentials are stored in a metadata > > directory located in the parent directory. This is okay for all paths with > > the notable exception of the root path, since we don't want and probably > > can't create a metadata directory above the virtfs directory on the host. > > > > This patch introduces a dedicated metadata file, sitting in the virtfs root > > for this purpose. It relies on the fact that the "." name necessarily refer > > > > s/refer/refers/ > I'll fix this. > > to the virtfs root. > > > > As for the metadata directory, we don't want the client to see this file. > > The current code only cares for readdir() but there are many other places > > to fix actually. The filtering logic is hence put in a separate function. > > > > Before: > > > > # ls -ld > > drwxr-xr-x. 3 greg greg 4096 May 5 12:49 . > > # chown root.root . > > chown: changing ownership of '.': Is a directory > > # ls -ld > > drwxr-xr-x. 3 greg greg 4096 May 5 12:49 . > > > > After: > > > > # ls -ld > > drwxr-xr-x. 3 greg greg 4096 May 5 12:49 . > > # chown bin.bin . > > # ls -ld > > drwxr-xr-x. 3 root root 4096 May 5 12:50 . > > Huh? How does chown bin.bin result in root.root? Copy-and-paste error? > Oops, I had first tested with bin.bin, then I decided that root.root would make more sense but I fumbled when updating the changelog... :-\ > > > > and from the host: > > > > ls -al .virtfs_metadata_root > > -rwx------. 1 greg greg 26 May 5 12:50 .virtfs_metadata_root > > $ cat .virtfs_metadata_root > > virtfs.uid=0 > > virtfs.gid=0 > > So what happens if the guest tries to manipulate > ./.virtfs_metadata_root? I know you are filtering it so that readdir() > and such can't see it, but do you have sane errors for the guest's > attempt to circumvent those hidden names? > This is addressed by patch 5. > > > > Reported-by: Léo Gaspard <l...@gaspard.io> > > Signed-off-by: Greg Kurz <gr...@kaod.org> > > --- > > hw/9pfs/9p-local.c | 88 > > ++++++++++++++++++++++++++++++++++++---------------- > > 1 file changed, 61 insertions(+), 27 deletions(-) > > > > diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c >
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