The mount namespace has supported id retrieval for a while already.
Add support for the other types as well.

Signed-off-by: Christian Brauner <brauner@kernel.org>
---
 fs/nsfs.c                 | 25 +++++++++++++------------
 include/uapi/linux/nsfs.h |  6 ++++--
 2 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/fs/nsfs.c b/fs/nsfs.c
index 22765fcab18e..8484bc4dd3de 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -177,6 +177,7 @@ static bool nsfs_ioctl_valid(unsigned int cmd)
 	case NS_GET_TGID_FROM_PIDNS:
 	case NS_GET_PID_IN_PIDNS:
 	case NS_GET_TGID_IN_PIDNS:
+	case NS_GET_ID:
 		return true;
 	}
 
@@ -226,18 +227,6 @@ static long ns_ioctl(struct file *filp, unsigned int ioctl,
 		argp = (uid_t __user *) arg;
 		uid = from_kuid_munged(current_user_ns(), user_ns->owner);
 		return put_user(uid, argp);
-	case NS_GET_MNTNS_ID: {
-		__u64 __user *idp;
-		__u64 id;
-
-		if (ns->ops->type != CLONE_NEWNS)
-			return -EINVAL;
-
-		mnt_ns = container_of(ns, struct mnt_namespace, ns);
-		idp = (__u64 __user *)arg;
-		id = mnt_ns->ns.ns_id;
-		return put_user(id, idp);
-	}
 	case NS_GET_PID_FROM_PIDNS:
 		fallthrough;
 	case NS_GET_TGID_FROM_PIDNS:
@@ -283,6 +272,18 @@ static long ns_ioctl(struct file *filp, unsigned int ioctl,
 			ret = -ESRCH;
 		return ret;
 	}
+	case NS_GET_MNTNS_ID:
+		if (ns->ops->type != CLONE_NEWNS)
+			return -EINVAL;
+		fallthrough;
+	case NS_GET_ID: {
+		__u64 __user *idp;
+		__u64 id;
+
+		idp = (__u64 __user *)arg;
+		id = ns->ns_id;
+		return put_user(id, idp);
+	}
 	}
 
 	/* extensible ioctls */
diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h
index fa86fe3c8bd3..5d5bf22464c9 100644
--- a/include/uapi/linux/nsfs.h
+++ b/include/uapi/linux/nsfs.h
@@ -16,8 +16,6 @@
 #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)
-/* Get the id for a mount namespace */
-#define NS_GET_MNTNS_ID		_IOR(NSIO, 0x5, __u64)
 /* Translate pid from target pid namespace into the caller's pid namespace. */
 #define NS_GET_PID_FROM_PIDNS	_IOR(NSIO, 0x6, int)
 /* Return thread-group leader id of pid in the callers pid namespace. */
@@ -42,6 +40,10 @@ struct mnt_ns_info {
 /* Get previous namespace. */
 #define NS_MNT_GET_PREV		_IOR(NSIO, 12, struct mnt_ns_info)
 
+/* Retrieve namespace identifiers. */
+#define NS_GET_MNTNS_ID		_IOR(NSIO, 5,  __u64)
+#define NS_GET_ID		_IOR(NSIO, 13, __u64)
+
 enum init_ns_ino {
 	IPC_NS_INIT_INO		= 0xEFFFFFFFU,
 	UTS_NS_INIT_INO		= 0xEFFFFFFEU,

-- 
2.47.3