issue with unsetting 'arch' flag

[Jaakko Heinonen]

On 2010-10-06, Alexander Best wrote:
> $ sudo rm -d /tmp/chflags.XXXXXX
> $ tmpfile=`mktemp /tmp/chflags.XXXXXX`
> $ sudo chflags arch $tmpfile
> $ chflags noarch $tmpfile
> 
> is what's causing the problem. the last chflags call should fail, but it
> doesn't.

Here is a patch for UFS:

%%%
Index: sys/ufs/ufs/ufs_vnops.c
===================================================================
--- sys/ufs/ufs/ufs_vnops.c	(revision 213507)
+++ sys/ufs/ufs/ufs_vnops.c	(working copy)
@@ -556,6 +556,9 @@ ufs_setattr(ap)
 			    & (SF_NOUNLINK | SF_IMMUTABLE | SF_APPEND) ||
 			    (vap->va_flags & UF_SETTABLE) != vap->va_flags)
 				return (EPERM);
+			if ((ip->i_flags & SF_SETTABLE) !=
+			    (vap->va_flags & SF_SETTABLE))
+ 				return (EPERM);
 			ip->i_flags &= SF_SETTABLE;
 			ip->i_flags |= (vap->va_flags & UF_SETTABLE);
 			DIP_SET(ip, i_flags, ip->i_flags);
%%%

The patch has a potential to break something if someone assumes that
non-super-user can modify UF_SETTABLE flags with the SF_SETTABLE part
set to zero. However with a quick peek this seems to be what NetBSD
does.

-- 
Jaakko