On Tue, Oct 30, 2001 at 07:36:26AM -0800, Jason R Thorpe wrote:
> On Tue, Oct 30, 2001 at 10:28:24AM -0500, Thor Lancelot Simon wrote:
> 
>  > It seems to me there are three choices: let programs lose when their shared
>  > libraries are switched out from under them, let users make arbitrary readable
>  > files read-only, or enforce the "x" bit the right way.
> 
> But even what you're suggesting wouldn't be "the right way".  Add +x to
> libc.so and then do "./libc.so".  This isn't really what you want, either.

| pla-muek# ls -l libc.so
| lrwxr-xr-x  1 root  wheel  13 Oct  4 05:35 libc.so -> libc.so.12.79
| pla-muek# chmod 777 libc.so.12.79
| pla-muek# !.
| ./libc.so
| ./libc.so: Exec format error. Wrong Architecture.
| pla-muek# 

I don't see how this is a particular problem.  It's approximately what
happened under 4BSD if you tried to execute the kernel, which was usually
mode 755, for example.  "Don't put /usr/lib in your search path if you're
so easily confused".  Or, as Chris said, fix execve.  Either way, it's a
lot better than letting arbitrary users make files unwritable.

-- 
Thor Lancelot Simon	                                      tls@rek.tjls.com
    And now he couldn't remember when this passion had flown, leaving him so
  foolish and bewildered and astray: can any man?
						   William Styron