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Message-ID: <e7d8f83e0710301921m3460f8dfkce72c4fc549ded4a@mail.gmail.com> Date: Wed, 31 Oct 2007 12:21:07 +1000 From: "Peter Dolding" <oiaohm@...il.com> To: linux-kernel@...r.kernel.org, linux-security-module@...r.kernel.org Subject: Re: Linux Security *Module* Framework (Was: LSM conversion to static interface) On 10/31/07, david@...g.hm <david@...g.hm> wrote: > On Wed, 31 Oct 2007, Peter Dolding wrote: > > > MultiAdmin loaded before Selinux breaks Selinux since Multi Admin rules are > > applied over using Selinux rules. This is just the way it is stacking LSM's > > is Just not healthy you always risk on LSM breaking another. Part of the > > reason why I have suggested a complete redesign of LSM. To get away from > > this problem of stacking. > > since the method of stacking hasn't been determined yet, you can't say > this. I can because that is the current day problem. With many LSM's loaded they stack completely as a complete mess and with problems. They fight with each other. Lack of define on stacking equals big problems. Since you have not created a standard for stacking does not stop the problem from existing. Nice lack of planing when LSM started or maybe its intentional. When you need stacking its about time you start moving things into the OS? There is a way around the problem too without allowing LSM to stack. Good advantage backward compatible because your are not playing with the LSM standard to do it so no LSM modules should need large alterations. At worse mirror extensions to handle the new OS feature. Posix File Capabilities provide the solution. First done as a LSM risked conflict. Moved in as a operating system extension by by conflict. Fragments from LSM's should exactly move that way if they expect to be overlapped by other models. Lot of stacking problems can be avoided if segments are complete standard extensions. > > it would be possible for MultiAdmin to grant additional access, that > SELinux then denies for it's own reasons. > > if the SELinux policy is written so that it ignores capabilities, and > instead just looks at uid0 then that policy is broken in a stacked > environment, but it's the polciy that's broken, not the stacking. That is not how current day always works. MultiAdmin grants and that can be the end of the treeing. Selinux does not get asked if it refuses it or not. So no matter what was set in the Selinux policy it may never get used. Adding more layers is also bad for performance to. Treeing threw modules for rights is a really slow process. As like a posix feature extension. Selinux/Other LSM's is at top of allocation no flaw no bypass. > yes, there will be interactions that don't make sense, but just becouse > something can be used wrong doesn't mean that there aren't other cases > where it can be used properly. > We are talking security here if its not order safe its not good. MultiAdmin done as a posix feature extension is order safe. MultiAdmin done as a LSM is not order safe. System Admins are humans too. Getting orders backwards does happen. So should be avoided where able. This completely avoids the need for adding another layer of stacking and since built inside current day framework. Does doing this risk the end of LSM's as we know it yes it does. Since it is not being used as LSM were intended. LSM is just a addon to standard OS security what is either a testing ground for new features to secure the OS that get build into the OS in time or as location for security modules. Somethings should be just done in the Standard OS security nothing to do with LSM. Little bit hard for some I guess to hear that LSM are not all important and not all Security features should be done in them. Some should be done in the main OS security features. Biggest current day problem with LSM is they have forgot that LSM is only a testing ground or a zone for features that people will only want some of the time. MultiAdmin is a feature that can enhance means to Audit OS ie who did what. Enhance security hand outs and can be really handy with almost any LSM on the system. Its description of what it is sounds very much like every other standard feature. Lets end the bitrot. Start having bits go into the main OS security features where they should be. Peter Dolding - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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