Re: [exim] 551 User not local; please try <forward-path>

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Auteur: Magnus Holmgren
Date:  
À: exim-users
Sujet: Re: [exim] 551 User not local; please try <forward-path>
On Saturday 17 June 2006 22:22, Robert Millan took the opportunity to write:
> On Sat, Jun 17, 2006 at 09:59:32PM +0200, Magnus Holmgren wrote:
> > > It seems it needs a bit more than access to the files:
> > >
> > > 2006-06-17 21:33:04 unable to set gid=1001 or uid=1001 (euid=102):
> > > userforward router (recipient is xxx@yyy)
> > >
> > > The ~/.forward files are world-readable, so why does it attempt
> > > setgid/setuid? Can we still avoid running exim as root?
> >
> > Yeees, I forgot that. Exim always tries to setuid/setgid to the user and
> > group given by those options or check_local_user, for security reasons I
> > think. You could add a verify_only router, but then you can't use $home.
>
> I don't understand. How can failure to drop privileges be a critical
> error? When it runs as root, this never happens. When it runs as user, it
> isn't necessary (although access could be denied if user is not the same).


Because if you allow user-supplied filter files to be run as the exim user,
the users can (by default) do anything they want as that user. It's not root,
but it still has privileges users aren't supposed to have.

-- 
Magnus Holmgren        holmgren@???
                       (No Cc of list mail needed, thanks)