On Fri, Apr 25, 2014 at 1:25 PM, Eric W. Biederman <[email protected]> wrote: > Andy Lutomirski <[email protected]> writes: > >> On Fri, Apr 25, 2014 at 12:37 PM, Eric W. Biederman >> <[email protected]> wrote: >>> Andy Lutomirski <[email protected]> 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. --Andy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
