On Mon, Apr 10, 2017 at 9:26 PM, Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote: > On 4/10/2017 11:30 AM, Djalal Harouni wrote: >> On Mon, Apr 10, 2017 at 5:50 PM, Casey Schaufler <casey@xxxxxxxxxxxxxxxx> wrote: >>> On 4/9/2017 3:42 AM, Djalal Harouni wrote: >>>> From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> [...] >>> While I appreciate your enthusiasm, I would really like >>> to see a mechanism for managing all of the blobs as being >>> potentially shared rather than just the task blob. With >>> infrastructure blob management being the general case we >>> could stack any set of existing modules that does not >>> include both SELinux and Smack. (AppArmor is threatening >>> to join that set, but we're still waiting on that) I >> Yes! most of the other kernel maintainers I discussed the feature with >> did not even believe or knew that LSM stacking is possible! Some other >> kernel frameworks are being replaced with new ones (I'm not sure if >> the old ones were perfect!)... but what I'm trying to say is that we >> should make it easy for dynamic LSM plugins model so they can explore >> the interface, and maybe after some time the whole framework will even >> be replaced with a better one... > > I'm not committing to dynamic modules, but I am working > to make sure I don't do anything to prevent someone else > from doing it in the future. There are a good number of > people who find the notion of dynamic security policy > disturbing. I understand, though that with today's container recycling use cases some of it may make sense. Anyway you are doing the real work, you know better. >> Thanks to your effort and others we may achieve it, but I don't think >> that delaying features for a perfect implementation is the best way. >> During linuxcon 2016 Europe you said that there should be a new kind >> of LSMs, that's why I think we should make it easy for that to happen. > > I agree that it's better to use a work-around today then to > let the shortcomings of the existing infrastructure stop you > from getting your job done. Indeed! >> >>> think it's a bad idea to go ahead with one implementation >>> for task blobs without taking care of the others. >> Ok. Sorry if I missed this, but could you please point me why this >> could be a bad idea ? > > It's a whole lot easier to maintain one sort of blob > management then a different kind for each blob. It would > be lots cleaner to have a single call that tells the > infrastructure how much space you need for all your blobs > than a separate interface for each. I perfectly agree here. With Tetsuo patch it was easy to add a stackable LSM, with a consistent approach that would be even better. But as you note that should not be a blocker to upstream new stackable LSMs. >> As I understand it, these are internal details that could be replaced. >> My first implementation used resizable concurrent hashtables that are >> heavily used in the networking code and it worked, and I easily >> converted the module to use Tetsuo's approach since I didn't see any >> objection for it, and it continued to work. Maybe the point should be >> *which* LSM should use the task->security and how ? The >> ModAutoRestrict module is a simple LSM which could easily work with >> any provided solution. > > So I see. > >> That being said, I could convert the module back and stick with >> rhashtables for now since it does not conflict with any module and it >> works well. I would like to avoid same history where Apparmor, Smack >> and TOMOYO all suffered to get mainlined, even Yama due to some >> requests... Then I can convert the module back to use the same LSM >> infrastructure if you maintainers think that how it should go, that's >> totally fine by me. Yama internally could use the same task blob but >> it is avoiding conflicts by using lists to manage its internal data, >> that's the same design with ModAutoRestrict and rhashtables. > > I think that would be the prudent approach. There is still > the possibility that blob sharing (or full stacking, if you > prefer) won't be accepted any time soon. Ok Casey! I will wait for more feedback, and if other maintainers do not object, I will convert it back to rhashtables in next iterations making sure that it should be simple to convert later to a blob sharing mechanism. Thanks again for the comments! -- tixxdz -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
