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Date:      Tue, 31 Oct 2000 11:27:18 -0500 (EST)
From:      Robert Watson <rwatson@FreeBSD.org>
To:        freebsd-stable@FreeBSD.org
Subject:   Heads up to jail() users in -STABLE
Message-ID:  <Pine.NEB.3.96L.1001031112044.58688t-100000@fledge.watson.org>

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The issue has been raised on -security that jail() doesn't virtualize the
System V IPC namespace.  This is not a security hole per se, as jail
doesn't claim to address it, but it may have undesirable properties at
some sites.  Rather than leave it in its current "not well defined state",
I recently committed changes to -CURRENT that disable access to System V
IPC from within jails by default, restricting use of these features to the
host environment, in effect collapsing it into a single host namespace.

It can be turned back on again using the sysctl jail.sysvipc_allowed, and
setting that MIB entry to 1.  This means that operators will be surprised
that their System V IPC application will simply fail to run in jail,
instead of having odd interactions with other System V IPC applications in
other jails, or in the host environment.  For example, postgresql will now
refuse to run in jail().  Most applications, however, will be unaffected
by this change.  This feature is documented in the jail.8 manpage (or will
be in -STABLE when the backport occurs), so it will be easy for
administrators to re-enable System V IPC if that is appropriate in their
environment. 

I have received permission from the release engineer to backport this to
-STABLE in time for the upcoming 4.2 release, and plan to do so this
evening, pending reasonable objections.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Project
robert@fledge.watson.org      NAI Labs, Safeport Network Services



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