On Mon, Jan 30, 2012 at 4:18 PM, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote: > On Mon, 2012-01-30 at 16:58 -0500, Colin Walters wrote: >> On Mon, 2012-01-30 at 08:17 -0800, Andy Lutomirski wrote: >> > Chroot can easily be used to subvert setuid programs. If no_new_privs, >> > then setuid programs don't gain any privilege, so allow chroot. >> >> Is this needed/desired by anyone now, or are you just using it to "demo" >> NO_NEW_PRIVS? I don't see it as very useful on its own, since in any >> "container"-type chroot you really want /proc and /dev, and your patch >> doesn't help with that. >> >> System daemons that do chroot for a modicum of security already start >> privileged, so this doesn't help them either. > > I thought this was all for sandboxing? If a browers (or user) wants to > run some untrusted code, perhaps a chroot is the best way to do so. It > just will break if it needs to access /proc or /dev. And perhaps we > don't want untrusted code accessing /proc and /dev. Interestingly, I believe this change would work for the Chromium setuid sandbox[1]. It uses a fancy clone trick (CLONE_FS) to start the process then chroot once all its dependencies are loaded. It then chroot()s to /proc/self/fd_info (or another empty process-specific directory). Of course, pid namespacing still wouldn't be there, but it'd be nice to have a fallback if someone doesn't want the sandboxing setup code to have privileges (or can only install unpriv'd code). cheers! will 1 - http://code.google.com/p/setuid-sandbox/source/browse/privdrop.c -- 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
