On Tue 21-03-17 11:38:49, J. Bruce Fields wrote:
> On Sun, Mar 19, 2017 at 11:19:43AM +0100, Jan Kara wrote:
> > On Tue 14-03-17 13:18:01, Amir Goldstein wrote:
> > > On Tue, Mar 14, 2017 at 1:03 AM, Filip Štědronský <r.lklm@xxxxxxxxxx> wrote:
> > > > Besause fanotify requires `struct path`, the event cannot be generated
> > > > directly in `fsnotify_move` and friends because they only get the inode
> > > > (and their callers, `vfs_rename`&co. cannot supply any better info).
> > > > So instead it needs to be generated higher in the call chain, i.e. in
> > > > the callers of functions like `vfs_rename`.
> > > >
> > > > This leads to some code duplication. Currently, there are several places
> > > > whence functions like `vfs_rename` or `vfs_unlink` are called:
> > > >
> > > > * syscall handlers (done)
> > > > * NFS server (done)
> > > > * stacked filesystems
> > > > - ecryptfs (done)
> > > > - overlayfs
> > > > (Currently doesn't report even ordinary fanotify events, because
> > > > it internally clones the upper mount; not sure about the
> > > > rationale. One can always watch the overlay mount instead.)
> > > > * few rather minor things
> > > > - devtmpfs
> > > > (its internal changes are not tied to any vfsmount so it cannot
> > > > emit mount-scoped events)
> > > > - cachefiles (done)
> > > > - ipc/mqueue.c (done)
> > > > - fs/nfsd/nfs4recover.c (done)
> > > > - kernel/bpf/inode.c (done)
> > > > net/unix/af_unix.c (done)
> > > >
> > > > (grep -rE '\bvfs_(rename|unlink|mknod|whiteout|create|mkdir|rmdir|symlink|link)\(')
> > > >
> > > > Signed-off-by: Filip Štědronský <r.lkml@xxxxxxxxxx>
> > > >
> > > > ---
> > > >
> > > > An alternative might be to create wrapper functions like
> > > > vfs_path_(rename|unlink|...). They could also take care of calling
> > > > security_path_(rename|unlink|...), which is currently also up to
> > > > the indvidual callers (possibly with a flag because it might not
> > > > be always desired).
> > >
> > > That's an interesting idea. There is some duplicity between security/audit
> > > hook and fsnotify hooks. It should be interesting to try and deduplicate
> > > some of this code.
> >
> > Yeah, but ecryptfs or nfsd don't actually call these security hooks AFAICT.
>
> We don't? E.g. nfsd_unlink calls vfs_unlink which calls
> security_inode_unlink().
OK, I have not been specific enough :). ecryptfs or nfsd don't call *path*
security hooks AFAICT - e.g. security_path_unlink() from nfsd_unlink().
Honza
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
