d95fa3c76a
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>
19 lines
576 B
C
19 lines
576 B
C
#ifndef __LINUX_NSFS_H
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#define __LINUX_NSFS_H
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#include <linux/ioctl.h>
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#define NSIO 0xb7
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/* Returns a file descriptor that refers to an owning user namespace */
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#define NS_GET_USERNS _IO(NSIO, 0x1)
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/* Returns a file descriptor that refers to a parent namespace */
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#define NS_GET_PARENT _IO(NSIO, 0x2)
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/* Returns the type of namespace (CLONE_NEW* value) referred to by
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file descriptor */
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#define NS_GET_NSTYPE _IO(NSIO, 0x3)
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/* Get owner UID (in the caller's user namespace) for a user namespace */
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#define NS_GET_OWNER_UID _IO(NSIO, 0x4)
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#endif /* __LINUX_NSFS_H */
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