Re: lynx-dev /tmp failure

[T.E.Dickey]

> 
> >  
> > Linux is a bad platform for testing permissions problems since it doesn't 
> > behave as stringently as Unix.  (I can read from a directory which has 
> > "unreadable" permissions - though I've not rechecked that with the 2.2.x 
> > kernel yet). 
>  
> Can you give a concrete example and confirm that you were not root at the 
> time.  This would be a serious bug that would probably get high priority 
> treatment given its security implications. 

at the moment I'm on the 2.2.5 kernel (Redhat 6) and of course was up too
late - I don't see it here, but my experience (with the 2.0.x kernel, libc5)
was that I could set a directory to be unexecutable and still read the file
if I knew its name.

I 'noticed' this last fall, for instance, when testing the permissions code
I was working on in Lynx.  I normally don't run as root.

-- I'll experiment some when I go back to the 2.0.36 this afternoon (I was
running 2.0.34 last fall, but I don't want to pull out the disk right now)
  
> Just to be clear, though, to read a file in Unix you need x permission 
> on the directory and r permission on the file; you do not need r 
> permission on the directory. 

yes - Solaris agrees with this.
  
> All the following are correct behaviour for Unix (as well as Linux). 
>  
> bash$ uname -a 
> Linux djwhome 2.0.36 #5 Thu Jun 10 23:33:21 BST 1999 i686 
> bash$ id 
> uid=501(david) gid=100(users) groups=100(users),11(floppy),101(setihome) 
> bash$ ls -ld /root 
> drwxr-x--x   8 root     root         2048 Aug 19 22:51 /root 
> bash$ ls /root 
> ls: /root: Permission denied 
> bash$ ls -l /root/lodlin16.zip 
> -rw-r--r--   1 root     root        95676 May  5  1996 /root/lodlin16.zip 
> bash$ wc /root/lodlin16.zip 
>     360    2165   95676 /root/lodlin16.zip 
> bash$ 


-- 
Thomas E. Dickey
address@hidden
http://www.clark.net/pub/dickey