From: Andrey Vagin <avagin@xxxxxxxxxx>
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.
Signed-off-by: Andrei Vagin <avagin@xxxxxxxxxx>
---
fs/nsfs.c | 4 ++++
include/linux/proc_ns.h | 1 +
include/uapi/linux/nsfs.h | 2 ++
kernel/pid_namespace.c | 19 +++++++++++++++++++
kernel/user_namespace.c | 1 +
5 files changed, 27 insertions(+)
diff --git a/fs/nsfs.c b/fs/nsfs.c
index be7d193..11a4b15 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -170,6 +170,10 @@ static long ns_ioctl(struct file *filp, unsigned int ioctl,
switch (ioctl) {
case NS_GET_USERNS:
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:
return -ENOTTY;
}
diff --git a/include/linux/proc_ns.h b/include/linux/proc_ns.h
index ca85a43..12cb8bd 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h
@@ -19,6 +19,7 @@ struct proc_ns_operations {
void (*put)(struct ns_common *ns);
int (*install)(struct nsproxy *nsproxy, 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;
diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h
index 5cacd5c..3af6172 100644
--- a/include/uapi/linux/nsfs.h
+++ b/include/uapi/linux/nsfs.h
@@ -7,5 +7,7 @@
/* Returns a file descriptor that refers to an owning user namespace */
#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 */
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index c18f0f4f..aad470b 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -405,6 +405,24 @@ static int pidns_install(struct nsproxy *nsproxy, struct ns_common *ns)
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)
{
return to_pid_ns(ns)->user_ns;
@@ -417,6 +435,7 @@ const struct proc_ns_operations pidns_operations = {
.put = pidns_put,
.install = pidns_install,
.owner = pidns_owner,
+ .get_parent = pidns_get_parent,
};
static __init int pid_namespaces_init(void)
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 42a64d5..33b523c 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -1080,6 +1080,7 @@ const struct proc_ns_operations userns_operations = {
.put = userns_put,
.install = userns_install,
.owner = userns_owner,
+ .get_parent = ns_get_owner,
};
static __init int user_namespaces_init(void)
--
2.5.5
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