Eric, during the container reboot discussion, the agreement was reached that rebooting for real fron non-init pid ns is not safe. Restarting userspace (in pidns caller owns) is. I argue the same reasoning supports this. I haven't had a chance to review the patch, but the idea gets my ack. I'll look at the patch asap. I'm also fine with splitting cap_sys_boot into a user and system caps. The former would only be needed targeted to the userns of the init pid, while the latter would be required to init_user_ns. Then containers could safely be given cap_sys_restart or whatever, but not cap_sys_boot which authorizes kexec and machine reset/poweroff. ----- Original message ----- > "Daniel P. Berrange" <berrange@xxxxxxxxxx> wrote: > > > On Fri, Aug 03, 2012 at 05:45:40AM -0700, Eric W. Biederman wrote: > > > The solution is to use user namespaces and to only test ns_capable on > > the magic reboot path. > > > > > > For the 3.7 timeframe that should be a realistic solution. > > > > Hmm, that would imply that if LXC wants to allow reboot()/CAP_SYS_BOOT > > they will be forced to use CLONE_NEWUSER. I was rather looking for a > > way > > to allow the container to keep CAP_SYS_BOOT, without also mandating use > > of user namespaces. > > If we remove the use of CAP_SYS_BOOT on the container reboot path > perhaps. > > But you have hit one small issue in the huge pile of issues why giving > contaners capabilities is generally a bad idea. > > This is the reason I have been insisting on a reasonable version of user > namespaces for a long time. > > When the security issues become important it is time for user > namespaces. That is their purpose. > > Eric > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" > in the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
