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Message-Id: <1497015878.21594.201.camel@linux.vnet.ibm.com> Date: Fri, 09 Jun 2017 09:44:38 -0400 From: Mimi Zohar <zohar@...ux.vnet.ibm.com> To: Matt Brown <matt@...tt.com>, Kees Cook <keescook@...omium.org> Cc: James Morris <james.l.morris@...cle.com>, "Serge E. Hallyn" <serge@...lyn.com>, LKML <linux-kernel@...r.kernel.org>, linux-security-module <linux-security-module@...r.kernel.org>, "kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com> Subject: Re: Re: [PATCH v2 1/1] Add Trusted Path Execution as a stackable LSM On Fri, 2017-06-09 at 09:18 -0400, Matt Brown wrote: > On 6/9/17 9:16 AM, Mimi Zohar wrote: > > On Fri, 2017-06-09 at 05:55 -0700, Kees Cook wrote: > >> On Fri, Jun 9, 2017 at 3:18 AM, Mimi Zohar <zohar@...ux.vnet.ibm.com> wrote: > >>> On Thu, 2017-06-08 at 23:50 -0400, Matt Brown wrote: > >>>>>> > >>>>>> * Issues: > >>>>>> * Can be bypassed by interpreted languages such as python. You can run > >>>>>> malicious code by doing: python -c 'evil code' > >>>>> > >>>>> What's the recommendation for people interested in using TPE but > >>>>> having interpreters installed? > >>>>> > >>>> > >>>> If you don't need a given interpreter installed, uninstall it. While > >>>> this is common sense system hardening it especially would make a > >>>> difference under the TPE threat model. > >>>> > >>>> I don't have a knock down answer for this. Interpreters are a hard > >>>> problem for TPE. > >>> > >>> You might be interested in the minor LSM named "shebang", that I > >>> posted as a proof of concept back in January, which restricts the > >>> python interactive prompt/interpreter, but allows the scripts > >>> themselves to be executed. > >> > >> https://patchwork.kernel.org/patch/9547405/ > >> > >> Maybe these could be merged and the interpreter string could be made > >> into a configurable list? > > > > I updated shebang, but didn't bother to post it, as nobody seemed to > > be interested at the time. The updated version already has support > > for the configurable list. Re-posting ... > > > > That would be awesome. I think it's the perfect complement to TPE as it > protects a key hole in its current threat model. Hm, I hadn't looked at it in since January. It still needs to be cleaned up and expanded a bit. The original version used a pathname for identifying the interpreter. This version converts the list of pathnames to a set of inodes, which is better, but now requires a method for updating the inode number after a software update. Please feel free to expand on it or re-use whatever you like. Mimi
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