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Commit a7306ed8 authored by Andrey Vagin's avatar Andrey Vagin Committed by Eric W. Biederman
Browse files

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: default avatarSerge Hallyn <serge@hallyn.com>
Signed-off-by: default avatarAndrei Vagin <avagin@openvz.org>
Signed-off-by: default avatarEric W. Biederman <ebiederm@xmission.com>
parent 6786741d

fs/nsfs.c

+4 −0
Original line number Original line Diff line number Diff line
@@ -171,6 +171,10 @@ static long ns_ioctl(struct file *filp, unsigned int ioctl, 
	switch (ioctl) {

	switch (ioctl) {

	case NS_GET_USERNS:

	case NS_GET_USERNS:

		return open_related_ns(ns, ns_get_owner);

		return open_related_ns(ns, ns_get_owner);

	case NS_GET_PARENT:

		if (!ns->ops->get_parent)

			return -EINVAL;

		return open_related_ns(ns, ns->ops->get_parent);

	default:

	default:

		return -ENOTTY;

		return -ENOTTY;

	}

	}

include/linux/proc_ns.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -19,6 +19,7 @@ struct proc_ns_operations { 
	void (*put)(struct ns_common *ns);

	void (*put)(struct ns_common *ns);

	int (*install)(struct nsproxy *nsproxy, struct ns_common *ns);

	int (*install)(struct nsproxy *nsproxy, struct ns_common *ns);

	struct user_namespace *(*owner)(struct ns_common *ns);

	struct user_namespace *(*owner)(struct ns_common *ns);

	struct ns_common *(*get_parent)(struct ns_common *ns);

};

};





extern const struct proc_ns_operations netns_operations;

extern const struct proc_ns_operations netns_operations;

include/uapi/linux/nsfs.h

+2 −0
Original line number Original line Diff line number Diff line
@@ -7,5 +7,7 @@ 




/* Returns a file descriptor that refers to an owning user namespace */

/* Returns a file descriptor that refers to an owning user namespace */

#define NS_GET_USERNS	_IO(NSIO, 0x1)

#define NS_GET_USERNS	_IO(NSIO, 0x1)

/* Returns a file descriptor that refers to a parent namespace */

#define NS_GET_PARENT	_IO(NSIO, 0x2)





#endif /* __LINUX_NSFS_H */
 
#endif /* __LINUX_NSFS_H */

kernel/pid_namespace.c

+19 −0
Original line number Original line Diff line number Diff line
@@ -388,6 +388,24 @@ static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns) 
	return 0;

	return 0;

}

}





static struct ns_common *pidns_get_parent(struct ns_common *ns)

{

	struct pid_namespace *active = task_active_pid_ns(current);

	struct pid_namespace *pid_ns, *p;



	/* See if the parent is in the current namespace */

	pid_ns = p = to_pid_ns(ns)->parent;

	for (;;) {

		if (!p)

			return ERR_PTR(-EPERM);

		if (p == active)

			break;

		p = p->parent;

	}



	return &get_pid_ns(pid_ns)->ns;

}



static struct user_namespace *pidns_owner(struct ns_common *ns)

static struct user_namespace *pidns_owner(struct ns_common *ns)

{

{

	return to_pid_ns(ns)->user_ns;

	return to_pid_ns(ns)->user_ns;
@@ -400,6 +418,7 @@ const struct proc_ns_operations pidns_operations = { 
	.put		= pidns_put,

	.put		= pidns_put,

	.install	= pidns_install,

	.install	= pidns_install,

	.owner		= pidns_owner,

	.owner		= pidns_owner,

	.get_parent	= pidns_get_parent,

};

};





static __init int pid_namespaces_init(void)

static __init int pid_namespaces_init(void)

kernel/user_namespace.c

+1 −0
Original line number Original line Diff line number Diff line
@@ -1034,6 +1034,7 @@ const struct proc_ns_operations userns_operations = { 
	.put		= userns_put,

	.put		= userns_put,

	.install	= userns_install,

	.install	= userns_install,

	.owner		= userns_owner,

	.owner		= userns_owner,

	.get_parent	= ns_get_owner,

};

};





static __init int user_namespaces_init(void)

static __init int user_namespaces_init(void)