On Sat, Oct 05, 2013 at 06:07:42PM -0500, Rob Landley wrote: > A todo item I've had _forever_ is fixing chroot() to not be broken > so that you can trivially break out of a chroot via: > > chdir("/"); > mkdir("sub"); > chroot("sub"); > chdir("./../../../../../../../.."); > > (Because chroot() affects where "/" points but NOT where "." points > to, and chdir does an == check with the dentry "/" points at to know > when to stop, so if you move "/" under "." you can back up to the > actual root of the tree.) > > The above is why lxc uses pivot_root() instead of chroot(). > > These days, we have multiple mount trees so there's no reason > chroot() can't trim the process local mount tree (creating a new > bind mount if necessary). Except my todo list runneth over and I > haven't had a chance to dig in and see what would be involved. (Last > time I brought this up people were wondering why chroot() didn't > just move "." to the new "/" if it wasn't under it. I had no idea, > still don't.)
1) RTFUNIXFAQ. chroot() never has been root-proof. 2) your "fix" isn't - it will lead to mounts done by chrooted process not affecting other processes in the same namespace. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/