On Mon, Nov 06, 2017 at 04:14:18PM -0600, Serge Hallyn wrote: > Quoting Daniel Micay (danielmicay@xxxxxxxxx): > > Substantial added attack surface will never go away as a problem. There > > aren't a finite number of vulnerabilities to be found. > > There's varying levels of usefulness and quality. There is code which I > want to be able to use in a container, and code which I can't ever see a > reason for using there. The latter, especially if it's also in a > staging driver, would be nice to have a toggle to disable. > > You're not advocating dropping the added attack surface, only adding a > way of dealing with an 0day after the fact. Privilege raising 0days can > exist anywhere, not just in code which only root in a user namespace can > exercise. So from that point of view, ksplice seems a more complete > solution. Why not just actually fix the bad code block when we know > about it? > > Finally, it has been well argued that you can gain many new caps from > having only a few others. Given that, how could you ever be sure that, > if an 0day is found which allows root in a user ns to abuse > CAP_NET_ADMIN against the host, just keeping CAP_NET_ADMIN from them > would suffice? It seems to me that the existing control in > /proc/sys/kernel/unprivileged_userns_clone might be the better duct tape > in that case. I agree that /proc/sys/kernel/unprivileged_userns_clone is the most reasonable thing to do. This patch introduces a layer of complexity to fine-tune user namespace creation that - in the relevant security critical scenario - should simply be turned of entirely. Is /proc/sys/kernel/unprivileged_userns_clone upstreamed or is this still only carried downstream? -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
