On Fri, Apr 25, 2014 at 2:17 PM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > Andy Lutomirski <luto@xxxxxxxxxxxxxx> writes: > >> On Fri, Apr 25, 2014 at 1:25 PM, Eric W. Biederman >> <ebiederm@xxxxxxxxxxxx> wrote: >>> Andy Lutomirski <luto@xxxxxxxxxxxxxx> writes: >>> >>>> On Fri, Apr 25, 2014 at 12:37 PM, Eric W. Biederman >>>> <ebiederm@xxxxxxxxxxxx> wrote: >>>>> Andy Lutomirski <luto@xxxxxxxxxxxxxx> writes: >>>>> >>>>>> Unless I'm missing some trick, it's currently rather painful to mount >>>>>> a namespace /proc. You have to actually be in the pid namespace to >>>>>> mount the correct /proc instance, and you can't unmount the old /proc >>>>>> until you've mounted the new /proc. This means that you have to fork >>>>>> into the new pid namespace before you can finish setting it up. >>>>> >>>>> Yes. You have to be inside just about all namespaces before you can >>>>> finish setting them up. >>>>> >>>>> I don't know the context in which needed to be inside the pid namespace >>>>> is a burden. >>>> >>>> I'm trying to sandbox myself. I unshare everything, setup up new >>>> mounts, pivot_root, umount the old stuff, fork, and wait around for >>>> the child to finish. >>>> >>>> This doesn't work: the parent can't mount the new /proc, and the child >>>> can't either because it's too late. >>>> >>>> The only solution I can think of without kernel changes is to fork the >>>> child (pid 1) before pivot_root, which makes everything more >>>> complicated. I suppose I can unshare, fork immediately, have the >>>> child set up all the mounts, and then wake the parent, but this is an >>>> annoying bit of extra complexity for no obvious gain. >>> >>> Or perhaps just use clone and clone flags. >>> >>> What are you doing with the parent process? What value does it serve? >> >> I'm not entirely sure. I'm hacking on this thing: >> >> https://github.com/amluto/sandstorm/tree/userns >> >> which isn't really my code. But there's an inner sandbox and an outer >> sandbox, and only the inner sandbox is in a pid namespace. >> >> I suppose what what I'm doing is a bit strange. > > A bit. But doing strange things is good. > > Right now most of my energy is focused on closely the last of the design > issues. So I don't have much energy for new namespace related features > right now. No problem. I may write up the patch, although I'll have to support current kernels anyway. --Andy _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
