"Michael Kerrisk (man-pages)" <mtk.manpages@xxxxxxxxx> writes: > Hello Eric, > > On 12/19/2016 11:53 PM, Eric W. Biederman wrote: >> "Michael Kerrisk (man-pages)" <mtk.manpages@xxxxxxxxx> writes: >> >>> Eric, >>> >>> The code proposed in this patch series is pretty small. Is there any >>> chance we could make the 4.10 merge window, if the changes seem >>> acceptable to you? >> >> I see why you are asking but I am not comfortable with aiming for >> the merge window that is on-going and could close at any moment. >> I have seen recenly too many patches that should work fine have >> some odd minor issue. Like an extra _ in a label used in an ifdef >> that resulted in memory stomps. Linus might be more brave but i would >> rather wait until the next merge window, so I don't need to worry about >> spoiling anyone's holidays with a typo someone over looked. > > I'll just gently ask if you'll reconsider and take another look at the > patches. They patches are very small, and don't change any existing > behavior. And if we see a problem in the next weeks they could be pulled. > In the meantime, I'd be aiming to publicize this API somewhat, so that we > might get some eyeballs to spot design bugs. But, I do understand your > position, if the answer is still "not for this merge window". My position is still not this merge window. I am more than happy to queue up the changes for the next one. Even on the best of days there is a reasonable chance Linus would not be happy to receive code development done in the merge window. I think there is also just a little bit of discussion that needs to happen with these new userspace APIs (below). And I have seen way too many times user space APIs added too quickly and having to be repaired afterwards. >> At first glance these patches seem reasonable. I don't see any problem >> with the ioctls you have added. >> >> That said I have a question. Should we provide a more direct way to >> find the answer to your question? Something like the access system >> call? >> >> I think a more direct answer would be more maintainable in the long run >> as it does not bind tools to specific implementation details in the >> future. Which could allow us to account for LSM policies and the like. > > My thoughts: > > 1. Regarding NS_GET_NSTYPE... It always struck me as a little odd > that you could ask setns() to check if the supplied FD referred > to a certain type of NS (and thus, in a round about way, setns() > gives us the same information as NS_GET_NSTYPE), but you can't > directly ask what the NS type is. The fact that setns() has this > facility suggests that there could be other uses for the operation > "tell me what type of NS this FD refers to". Yes. I have no problem with that one. > 2. Regarding NS_GET_CREATOR_UID... There are defined rules about what > this UID means with respect to capabilities in a namespace. It's > not an implementation detail, as I understand it. Also in terms of > introspecting to try to understand the structure of namespaces on > a running system, knowing this UID is useful in and of itself. I am not quite sold on the name NS_GET_CREATOR_UID. NS_GET_OWNER_UID seems to match the code better. The owner is the creator but the important part seems to be the ownership not the act of creation. > 3. NS_GET_NSTYPE and NS_GET_CREATOR_UID solve my problem, but > obviously your idea would make life simpler for user space. > Am I correct to understand that you mean an API that takes > three pieces of info: a PID, a capability, and an fd referring > to a /proc/PID/ns/xxx, and tells us whether PID has the specified > capability for operations in the specified namespace? Something like that. But yes something we can wire up to ns_capable_noaudit and be told the result. That will let the LSMs and any future kerel changes have their say, without any extra maintenance burden in the kernel. What I really don't want is for userspace to start depending on the current formula being the only factors that say if it has a capabliltiy in a certain situation because in practice that just isn't true. Permission checks just keep evoloving in the kernel. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
