Date: Mon, 3 Feb 2014 15:53:36 -0800 From: Doug Ambrisko <ambrisko@ambrisko.com> To: James Gritton <jamie@FreeBSD.org> Cc: src-committers@FreeBSD.org, svn-src-all@FreeBSD.org, Gleb Smirnoff <glebius@FreeBSD.org>, Robert Watson <rwatson@FreeBSD.org>, svn-src-head@FreeBSD.org, Alexander Leidinger <Alexander@Leidinger.net> Subject: Re: svn commit: r261266 - in head: sys/dev/drm sys/kern sys/sys usr.sbin/jail Message-ID: <20140203235336.GA46006@ambrisko.com> In-Reply-To: <52EC4DBB.50804@freebsd.org> References: <201401291341.s0TDfDcB068211@svn.freebsd.org> <20140129134344.GW66160@FreeBSD.org> <52E906CD.9050202@freebsd.org> <20140129222210.0000711f@unknown> <alpine.BSF.2.00.1401311231490.36707@fledge.watson.org> <20140131223011.0000163b@unknown> <52EC4DBB.50804@freebsd.org>
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On Fri, Jan 31, 2014 at 06:28:27PM -0700, James Gritton wrote: | On 1/31/2014 2:30 PM, Alexander Leidinger wrote: | > On Fri, 31 Jan 2014 12:34:48 +0000 (GMT) | > Robert Watson <rwatson@FreeBSD.org> wrote: | >> On Wed, 29 Jan 2014, Alexander Leidinger wrote: | >>>> It does. I included a warning in jail.8 that this will pretty | >>>> much undo jail security. There are still reasons some may want to | >>>> do this, but it's definitely not for everyone or even most people. | >>> | >>> It only "unjails" (= basically the same security level as the | >>> jail-host with the added benefit of the flexibility of a jail like | >>> easy moving from one system to another) the jail which has this | >>> flag set. All other jails without the flag can not "escape" to the | >>> host. | >>> | >>> I also have to add that just setting this flag does not give access | >>> to the host, you also have to configure a non-default devfs rule | >>> for this jail (to have the devices appear in the jail). | >> | >> This is not correct: devices do not need to be delegated in devfs for | >> PRIV_IO to allow bypass of the Jail security model, due to sysarch() | >> and the Linux-emulated equivalent, which turn out direct I/O access | >> from a user process without use of a device node. | > | > Ok, then it is just the non-default flag, not the additional devfs part. | > | > I agree with your other post that we are better of to document better | > what it means if an admin allows kmem access for a specific jail. | | I second the documentation route. Yes, it's true that this option | makes a totally insecure jail - at least one lacking the expected jail | security additions. But I think that while security is one of the | primary purposes of jails, it's not the only purpose. It should be | possible to have a trusted "master jail" that still takes advantage of | the encapsulation while allowing otherwise unsupported features such | as a desktop. | | The distinction of whether certain devices are required to break out | of a jail with allow.kmem is something of a red herring - the fact is | that anyone who wants this level of access is going to have the | devices in place anyway. | | I suppose "obviate" wasn't the best word for the situation. Maybe | something that starts with "WARNING: ..." is in order. It's unfortunate that vimage requires jail. I want to use vimage but not have the security restrictions of a jail. To do this I patched jail to basically let everything through. It would be nice to be able to run jail in an insecure mode which I understand is a contradition. I do use the jail infrastructure to set the uname*/getosreldate so that a specific jail thinks it is FreeBSD version blah. Then I can ssh into that jail and pkg_add things, make ports etc. I use this on my laptop running current on the base. My other jails run various versions of FreeBSD. I don't care about security in this case. Thanks, Doug A.
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