[PATCHES][BUG 13673] smbd: Fix DELETE_ON_CLOSE behaviour on files with READ_ONLY attribute

[Jeremy Allison]

On Fri, Nov 02, 2018 at 03:50:27PM -0700, Jeremy Allison via samba-technical wrote:
> On Fri, Nov 02, 2018 at 03:33:28PM -0700, Christof Schmitt wrote:
> > 
> > Yes. The attached patches cover both cases now. I also discovered that
> > when NT_STATUS_CANNOT_DELETE is returne for a new file, the file is
> > still created. The easiest fix seems to be to unlink again. The question
> > here is whether there is a good way to move the check for the new file
> > case before actually creating the file.
> 
> >  	/* Handle strange delete on close create semantics. */
> >  	if (create_options & FILE_DELETE_ON_CLOSE) {
> > +		if (new_file_created) {
> > +			status = can_set_delete_on_close(fsp,
> > +						 new_dos_attributes);
> > +			if (!NT_STATUS_IS_OK(status)) {
> > +				int ret;
> >  
> > -		status = can_set_delete_on_close(fsp, new_dos_attributes);
> > +				ret = SMB_VFS_UNLINK(conn, fsp->fsp_name);
> > +				if (ret != 0) {
> > +					DBG_INFO("Unlink of new file %s failed "
> > +						 "after DELETE_ON_CLOSE check "
> > +						 "returned %s: %s\n",
> > +						 smb_fname_str_dbg(smb_fname),
> > +						 nt_errstr(status),
> > +						 strerror(errno));
> > +				}
> > +			}
> > +		} else {
> > +			status = can_set_delete_on_close(fsp,
> > +						 existing_dos_attributes);
> > +		}
> >  
> >  		if (!NT_STATUS_IS_OK(status)) {
> >  			/* Remember to delete the mode we just added. */
> 
> I have to NAK the above I'm afraid. There's an inherent race
> condition to do with calling SMB_VFS_UNLINK() even if we just
> created the file.


Here is a version that is rebased on top of the latest master
I got through autobuild. Take a look at the changes I made
to the:

smbd: Fix DELETE_ON_CLOSE behaviour on files with READ_ONLY attribute

patch. It handles the delete-on-close of a new file *before*
we create the new file. Let me know if you're OK with it.

Cheers,

	Jeremy.
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