[PATCH 4/5] nsfs: add ioctl to get a parent namespace
From: Andrey Vagin <hidden>
Date: 2016-07-15 02:12:38
Also in:
linux-fsdevel, lkml
Subsystem:
filesystems (vfs and infrastructure), namespaces:, the rest · Maintainers:
Alexander Viro, Christian Brauner, Linus Torvalds
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: Andrey Vagin <redacted> --- fs/nsfs.c | 4 ++++ include/linux/proc_ns.h | 1 + include/uapi/linux/nsfs.h | 1 + kernel/pid_namespace.c | 26 ++++++++++++++++++++++++++ kernel/user_namespace.c | 1 + 5 files changed, 33 insertions(+)
diff --git a/fs/nsfs.c b/fs/nsfs.c
index 1e5d2d0..b607a42 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c@@ -169,6 +169,10 @@ 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 de0e771..1c9f720 100644
--- a/include/linux/proc_ns.h
+++ b/include/linux/proc_ns.h@@ -18,6 +18,7 @@ struct proc_ns_operations { struct ns_common *(*get)(struct task_struct *task); void (*put)(struct ns_common *ns); int (*install)(struct nsproxy *nsproxy, 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 7a09ede..88098ea 100644
--- a/include/uapi/linux/nsfs.h
+++ b/include/uapi/linux/nsfs.h@@ -5,5 +5,6 @@ #define NSIO 0xb7 #define NS_GET_USERNS _IO(NSIO, 0x1) +#define NS_GET_PARENT _IO(NSIO, 0x2) #endif /* __LINUX_NSFS_H */
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index 3529a03..a63adfb 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c@@ -388,12 +388,38 @@ 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; + + pid_ns = to_pid_ns(ns); + if (pid_ns == &init_pid_ns) { + if (capable(CAP_SYS_ADMIN)) + return ERR_PTR(-ENOENT); + return ERR_PTR(-EPERM); + } + + pid_ns = p = pid_ns->parent; + + for (;;) { + if (p == active) + break; + if (p == &init_pid_ns) + return ERR_PTR(-EPERM); + p = p->parent; + } + + return &get_pid_ns(pid_ns)->ns; +} + const struct proc_ns_operations pidns_operations = { .name = "pid", .type = CLONE_NEWPID, .get = pidns_get, .put = pidns_put, .install = pidns_install, + .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 6382e5e..d6ba0b8 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c@@ -1024,6 +1024,7 @@ const struct proc_ns_operations userns_operations = { .get = userns_get, .put = userns_put, .install = userns_install, + .get_parent = ns_get_owner, }; static __init int user_namespaces_init(void)
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2.5.5