On Tue, Apr 19, 2016 at 9:36 PM, Konstantin Khlebnikov <koc...@gmail.com> wrote: > On Wed, Apr 20, 2016 at 6:04 AM, Eric W. Biederman >> >> The kernel.pty.reserve sysctl is neutered with no way currently >> implemented to be able to use the reserved ptys. > > I think we could convert this into reserve for init user namespace, > ssh in host will work even if containers eaten all ptys.
Yes. That's basically how it effectively worked before (ie everything but the initial non-newinstance devpts mount would be limited to the non-reserved numbers). We required the non-init namespaces to do a newinstance mount, so the whole test for "newinstance" was effectively the same thing as just checking for the init namespace from a security standpoint. And in fact, rewriting it in that form (ie checking for init_ns) would just make it much more obvious what the intent it. Linus