Re: [gentoo-hardened] How to protect from /tmp hardlink/symlink attacks?

[Chris PeBenito]

On Mon, 2004-04-05 at 16:00, coldolph-hg@×××××.com wrote:
> I saw this portage bug (marked critical) and wondered
> if the default installation of either grsecurity or
> selinux flavor of hardened Gentoo would protect ..
>
> http://bugs.gentoo.org/show_bug.cgi?id=21923

Currently SELinux won't do anything about it.  Portage_t is allowed to
modify any file on the system (except device nodes).  However, in light
of this, it could be tightened up a little.  You could change the
current rule:

create_dir_notdevfile(portage_t,file_type)

To exclude user temp files:

create_dir_notdevfile(portage_t,{ file_type -user_tmp_t })

Therefore, portage_t can modify all files, except those created by
users, in /tmp.

> Then I am curious what would be the recommended path
> to add protection, if the default setup did not
> protect from this class of exploits?  It seems tricky
> to me, since ordinary users generally are allowed to
> write to /tmp, and the security context / userid of
> the portage user would allow emerge's to scribble in
> places that ordinary users should not.

-- 
Chris PeBenito
<pebenito@g.o>
Developer,
Hardened Gentoo Linux
Embedded Gentoo Linux
 
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