From 6786741dbf99e44fb0c0ed85a37582b8a26f1c3b Mon Sep 17 00:00:00 2001 From: Andrey Vagin Date: Tue, 6 Sep 2016 00:47:14 -0700 Subject: nsfs: add ioctl to get an owning user namespace for ns file descriptor Each namespace has an owning user namespace and now there is not way to discover these relationships. Understending namespaces relationships allows to answer the question: what capability does process X have to perform operations on a resource governed by namespace Y? After a long discussion, Eric W. Biederman proposed to use ioctl-s for this purpose. The NS_GET_USERNS ioctl returns a file descriptor to an owning user namespace. It returns EPERM if a target namespace is outside of a current user namespace. v2: rename parent to relative v3: Add a missing mntput when returning -EAGAIN --EWB Acked-by: Serge Hallyn Link: https://lkml.org/lkml/2016/7/6/158 Signed-off-by: Andrei Vagin Signed-off-by: Eric W. Biederman --- include/uapi/linux/nsfs.h | 11 +++++++++++ 1 file changed, 11 insertions(+) create mode 100644 include/uapi/linux/nsfs.h (limited to 'include') diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h new file mode 100644 index 000000000000..5cacd5c1b5d7 --- /dev/null +++ b/include/uapi/linux/nsfs.h @@ -0,0 +1,11 @@ +#ifndef __LINUX_NSFS_H +#define __LINUX_NSFS_H + +#include + +#define NSIO 0xb7 + +/* Returns a file descriptor that refers to an owning user namespace */ +#define NS_GET_USERNS _IO(NSIO, 0x1) + +#endif /* __LINUX_NSFS_H */ -- cgit v1.2.3-59-g8ed1b