On Fri, Apr 25, 2014 at 1:46 PM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote: > 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. That was a semi-useless link. This is better: https://github.com/amluto/sandstorm/blob/userns/src/sandstorm/supervisor-main.c%2B%2B --Andy _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
