Re: -mm -> 2.6.13 merge status (fuse)

[Miklos Szeredi]

> > > On the other hand, sometimes a root process, or some other user's
> > > process, might _want_ to give permission to allow a trusted FUSE
> > > filesystem the potential to monkey with it (return potentially
> > > untrusted information, or stop it entirely), in exchange for access to
> > > the filesystem.  So it would be nice if there was some way that a
> > > process could tell the kernel that it is willing to give permission to
> > > allow certain FUSE filesystems to potentially affect it.  Say, via a
> > > fnctl() call, perhaps.
> > 
> > Hmm.  'su' works for root.  
> 
> ??  Not sure what you're saying.

If user X mounts a filesystem, and root wants to access it, it can do
'su X' and see the otherwise inaccesible files.

> > How do you think fcntl() could be used?  I think a task flag settable
> > via prctl() would be more appropriate.
> 
> The problem with a task flag is that a root process might not want to
> give permission for _all_ user-mountable filesystem, but only certain
> ones.  So the idea is that the process should be able to specify
> specific mountpoints as being "ok" for the process to access.

OK, so you're saying, it should be a per-mountpoint flag, and not a
per-process one.

Then the solution is simple I think.  Root can just remount the
filesystem with the 'allow_other' flag (that's currently not possible,
because the remount_fs operation is not yet implemented).

Thanks,
Miklos
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