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OpenCloudOS-Kernel/include/uapi/linux/nsfs.h

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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 <serge@hallyn.com> Link: https://lkml.org/lkml/2016/7/6/158 Signed-off-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2016-09-06 15:47:14 +08:00
#ifndef __LINUX_NSFS_H
#define __LINUX_NSFS_H
#include <linux/ioctl.h>
#define NSIO 0xb7
/* Returns a file descriptor that refers to an owning user namespace */
nsfs: Add an ioctl() to return owner UID of a userns I'd like to write code that discovers the user namespace hierarchy on a running system, and also shows who owns the various user namespaces. Currently, there is no way of getting the owner UID of a user namespace. Therefore, this patch adds a new NS_GET_CREATOR_UID ioctl() that fetches the UID (as seen in the user namespace of the caller) of the creator of the user namespace referred to by the specified file descriptor. If the supplied file descriptor does not refer to a user namespace, the operation fails with the error EINVAL. If the owner UID does not have a mapping in the caller's user namespace return the overflow UID as that appears easier to deal with in practice in user-space applications. -- EWB Changed the handling of unmapped UIDs from -EOVERFLOW back to the overflow uid. Per conversation with Michael Kerrisk after examining his test code. Acked-by: Andrey Vagin <avagin@openvz.org> Signed-off-by: Michael Kerrisk <mtk-manpages@gmail.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2017-01-25 09:04:15 +08:00
#define NS_GET_USERNS _IO(NSIO, 0x1)
nsfs: add ioctl to get a parent namespace Pid and user namepaces are hierarchical. There is no way to discover parent-child relationships. In a future we will use this interface to dump and restore nested namespaces. Acked-by: Serge Hallyn <serge@hallyn.com> Signed-off-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2016-09-06 15:47:15 +08:00
/* Returns a file descriptor that refers to a parent namespace */
nsfs: Add an ioctl() to return owner UID of a userns I'd like to write code that discovers the user namespace hierarchy on a running system, and also shows who owns the various user namespaces. Currently, there is no way of getting the owner UID of a user namespace. Therefore, this patch adds a new NS_GET_CREATOR_UID ioctl() that fetches the UID (as seen in the user namespace of the caller) of the creator of the user namespace referred to by the specified file descriptor. If the supplied file descriptor does not refer to a user namespace, the operation fails with the error EINVAL. If the owner UID does not have a mapping in the caller's user namespace return the overflow UID as that appears easier to deal with in practice in user-space applications. -- EWB Changed the handling of unmapped UIDs from -EOVERFLOW back to the overflow uid. Per conversation with Michael Kerrisk after examining his test code. Acked-by: Andrey Vagin <avagin@openvz.org> Signed-off-by: Michael Kerrisk <mtk-manpages@gmail.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2017-01-25 09:04:15 +08:00
#define NS_GET_PARENT _IO(NSIO, 0x2)
nsfs: Add an ioctl() to return the namespace type Linux 4.9 added two ioctl() operations that can be used to discover: * the parental relationships for hierarchical namespaces (user and PID) [NS_GET_PARENT] * the user namespaces that owns a specified non-user-namespace [NS_GET_USERNS] For no good reason that I can glean, NS_GET_USERNS was made synonymous with NS_GET_PARENT for user namespaces. It might have been better if NS_GET_USERNS had returned an error if the supplied file descriptor referred to a user namespace, since it suggests that the caller may be confused. More particularly, if it had generated an error, then I wouldn't need the new ioctl() operation proposed here. (On the other hand, what I propose here may be more generally useful.) I would like to write code that discovers namespace relationships for the purpose of understanding the namespace setup on a running system. In particular, given a file descriptor (or pathname) for a namespace, N, I'd like to obtain the corresponding user namespace. Namespace N might be a user namespace (in which case my code would just use N) or a non-user namespace (in which case my code will use NS_GET_USERNS to get the user namespace associated with N). The problem is that there is no way to tell the difference by looking at the file descriptor (and if I try to use NS_GET_USERNS on an N that is a user namespace, I get the parent user namespace of N, which is not what I want). This patch therefore adds a new ioctl(), NS_GET_NSTYPE, which, given a file descriptor that refers to a user namespace, returns the namespace type (one of the CLONE_NEW* constants). Signed-off-by: Michael Kerrisk <mtk-manpages@gmail.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2017-01-25 09:03:36 +08:00
/* Returns the type of namespace (CLONE_NEW* value) referred to by
file descriptor */
nsfs: Add an ioctl() to return owner UID of a userns I'd like to write code that discovers the user namespace hierarchy on a running system, and also shows who owns the various user namespaces. Currently, there is no way of getting the owner UID of a user namespace. Therefore, this patch adds a new NS_GET_CREATOR_UID ioctl() that fetches the UID (as seen in the user namespace of the caller) of the creator of the user namespace referred to by the specified file descriptor. If the supplied file descriptor does not refer to a user namespace, the operation fails with the error EINVAL. If the owner UID does not have a mapping in the caller's user namespace return the overflow UID as that appears easier to deal with in practice in user-space applications. -- EWB Changed the handling of unmapped UIDs from -EOVERFLOW back to the overflow uid. Per conversation with Michael Kerrisk after examining his test code. Acked-by: Andrey Vagin <avagin@openvz.org> Signed-off-by: Michael Kerrisk <mtk-manpages@gmail.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2017-01-25 09:04:15 +08:00
#define NS_GET_NSTYPE _IO(NSIO, 0x3)
/* Get owner UID (in the caller's user namespace) for a user namespace */
#define NS_GET_OWNER_UID _IO(NSIO, 0x4)
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 <serge@hallyn.com> Link: https://lkml.org/lkml/2016/7/6/158 Signed-off-by: Andrei Vagin <avagin@openvz.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
2016-09-06 15:47:14 +08:00
#endif /* __LINUX_NSFS_H */