OSEC

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Subject: Re: FreeBSDDEATH.c.txt (mmap dirty page no check bug)
From: John Brazel (johntellurian.com.au)
Date: Wed Jun 07 2000 - 01:07:04 CDT

> >From a security standpoint a shared temporary filesystem coupled with
> applications written as they are can be an invitation for compromise.
> Suggestions ranging from no temporary filesystem at all to
> subdirectories in /tmp for each user have been discussed on
> FreeBSD-security and BUGTRAQ for many years. Of course for root
> /var/run reduces the risk. The concept of a virtual temporary
> filesystem for each user, e.g. /tmp as and address space addressable by
> a single process group and only sharable by that process group or even
> a single process, might go a long way to mitigate some of the risk.

        What exactly ARE all the risks? At the risk of 'over-enthusiasm'
        (for want of a better phrase), would a purpose-written,
        security-oriented filesystem solve it?

        Something like /tmp, but with an embedded sticky bit (permanently
        set) and the inability to create symlinks (the symlink(2) syscall
        would return ENOSYS for that filesystem).

        The question, of course, is, would this fix enough of the problems
        to warrant all the effort? At the very least, backward compatibility
        wouldn't be affected.

J.

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