Re: [RFC] FUSE permission modell (Was: fuse review bits)

[Jamie Lokier <jamie@shareable.org>]

Miklos Szeredi wrote:
> > Yes, for NFSv2, this test in nfs_permssion():
> > 
> > 	if (!NFS_PROTO(inode)->access)
> > 		goto out;
> 
> I've seen that, I just thought that was for some broken servers not
> for all NFSv2 servers.
> 
> Anyway that's been fixed in NFSv3, so obviously the "permission
> checking on both sides" wasn't optimal :)
> 
> > And for either version of NFS, if the uid and gid are non-zero, and
> > the permission bits indicate that an access is permitted, then the
> > client does not consult the server for permission.
> 
> Where's that?  I see no such check.

	/*
	 * Trust UNIX mode bits except:
	 *
	 * 1) When override capabilities may have been invoked
	 * 2) When root squashing may be involved
	 * 3) When ACLs may overturn a negative answer */
	if (!capable(CAP_DAC_OVERRIDE) && !capable(CAP_DAC_READ_SEARCH)
	    && (current->fsuid != 0) && (current->fsgid != 0)
	    && error != -EACCES)
		goto out;

-- Jamie
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