Each namespace has an owning user namespace and now there is not way to discover these relationships. Pid and user namepaces are hierarchical. There is no way to discover parent-child relationships too. Why we may want to know relationships between namespaces? One use would be visualization, in order to understand the running system. Another would be to answer the question: what capability does process X have to perform operations on a resource governed by namespace Y? One more use-case (which usually called abnormal) is checkpoint/restart. In CRIU we age going to dump and restore nested namespaces. There [1] was a discussion about which interface to choose to determing relationships between namespaces. Eric suggested to add two ioctl-s [2]: > Grumble, Grumble. I think this may actually a case for creating ioctls > for these two cases. Now that random nsfs file descriptors are bind > mountable the original reason for using proc files is not as pressing. > > One ioctl for the user namespace that owns a file descriptor. > One ioctl for the parent namespace of a namespace file descriptor. Here is an implementaions of these ioctl-s. [1] https://lkml.org/lkml/2016/7/6/158 [2] https://lkml.org/lkml/2016/7/9/101 Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> Cc: "Michael Kerrisk (man-pages)" <mtk.manpages@xxxxxxxxx> Cc: "W. Trevor King" <wking@xxxxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx> -- 2.5.5 -- 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
