Author: Sheldon Hearn Date: To: Philip Hazel CC: exim-users Subject: Re: [Exim] What to do about non-monitonic process ids
On (2003/02/05 10:30), Philip Hazel wrote:
> > > I don't think filenames need to be unpredictable in Exim.
> >
> > So when Exim delivers a message locally into a Maildir format mailbox,
> > it takes care not to follow a symlink, yes? :-)
>
> What am I missing here? What has unpredictable file names got to do with
> symlinks?
A local user can fool Exim into overwriting any group mail owned file on
the filesystem if
a) the user can write to a directory in which Exim tries to write a
file,
b) Exim tries to write that file with a predictable filename,
c) Exim uses a predictable filename, and
d) Exim accidentally follows a symlink.
The use of unpredictable filenames would be an added level of protection
against programming mistakes.
