On Fri, Feb 04, 2022 at 09:53:38AM +0300, Anton V. Boyarshinov wrote: > Idmapped mounts may have security implications [1] and have > no knobs to be disallowed at runtime or compile time. > > This patch adds a sysctl and a config option to set its default value. > > [1] https://lore.kernel.org/all/m18s7481xc.fsf@xxxxxxxxxxxxxxxxx/ > > Based on work from Alexey Gladkov <legion@xxxxxxxxxx>. > > Signed-off-by: Anton V. Boyarshinov <boyarsh@xxxxxxxxxxxx> > --- Thank your for the general idea, Anton. If you want to turn off idmapped mounts you can already do so today via: echo 0 > /proc/sys/user/max_user_namespaces Aside from that, idmapped mounts can only be created by fully privileged users on the host for a selected number of filesystems. They can neither be created as an unprivileged user nor can they be created inside user namespaces. I appreciate the worry. Any new feature may have security implications and bugs. In addition, we did address these allegations multiple times already (see [1], [2], [3], [4], [5]). As the author/maintainer of this feature, Nacked-by: Christian Brauner <brauner@xxxxxxxxxx> [1]: https://lore.kernel.org/lkml/20210213130042.828076-1-christian.brauner@xxxxxxxxxx/T/#m3a9df31aa183e8797c70bc193040adfd601399ad [2]: https://lore.kernel.org/lkml/m1r1ifzf8x.fsf@xxxxxxxxxxxxxxxxx [3]: https://lore.kernel.org/lkml/20210213130042.828076-1-christian.brauner@xxxxxxxxxx/T/#m59cdad9630d5a279aeecd0c1f117115144bc15eb [4]: https://lore.kernel.org/lkml/20210510125147.tkgeurcindldiwxg@wittgenstein [5]: https://lore.kernel.org/linux-fsdevel/CAHrFyr4AYi_gad7LQ-cJ9Peg=Gt73Sded8k_ZHeRZz=faGzpQA@xxxxxxxxxxxxxx
