Messages in this thread | | | Date | Wed, 13 Jul 2016 00:42:26 +0300 | From | Cyrill Gorcunov <> | Subject | Re: [PATCH] prctl: remove one-shot limitation for changing exe link |
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On Tue, Jul 12, 2016 at 08:29:33PM +0300, Cyrill Gorcunov wrote: > On Tue, Jul 12, 2016 at 11:52:09AM -0500, Eric W. Biederman wrote: > > > > > > Persistent exe-link doesn't guarantee anything if you have rights to ptrace > > > task and inject own code into (from security POV). So lets rip it out. > > > > > > Acked-by: Cyrill Gorcunov <gorcunov@openvz.org> > > > > I believe the original concern was someone injecting a code into a > > process and playing silly buggers with the exe link. Someone who does > > not have ptrace capability. > > If you manage to inject code into a process, that's all, you're > compromised, preventing changing exe-link several times wont help > much I fear. Current limit -- one may change it once, Stas' patch > simply removes this limitation. The ability to change it only _once_ > may be suitable for some kind of monitor daemon I guess but this > monitor should detect any change in exe-link state and notify > node's admin, otherwise it's simply useless. > > > It is completely not ok to change this until someone goes back to the > > original conversation and looks at the original threat model, and > > refutes it.
Btw, if the persistency of exe link is _that_ important (in which I'm really doubting) we always can use some of sysctl flag on host which would control it [by default it might be turned off but for those who really rely on exelink status, for some reason, the sysctl might be set up and prevent any exelink modification].
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