1 files changed, 97 insertions, 25 deletions

diff --git a/fs/nsfs.c b/fs/nsfs.c
index 07e22a15ef02..a4a925dce331 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -8,10 +8,12 @@
 #include <linux/magic.h>
 #include <linux/ktime.h>
 #include <linux/seq_file.h>
+#include <linux/pid_namespace.h>
 #include <linux/user_namespace.h>
 #include <linux/nsfs.h>
 #include <linux/uaccess.h>
 
+#include "mount.h"
 #include "internal.h"
 
 static struct vfsmount *nsfs_mnt;
@@ -82,40 +84,47 @@ int ns_get_path(struct path *path, struct task_struct *task,
 	return ns_get_path_cb(path, ns_get_path_task, &args);
 }
 
-int open_related_ns(struct ns_common *ns,
-		   struct ns_common *(*get_ns)(struct ns_common *ns))
+/**
+ * open_namespace - open a namespace
+ * @ns: the namespace to open
+ *
+ * This will consume a reference to @ns indendent of success or failure.
+ *
+ * Return: A file descriptor on success or a negative error code on failure.
+ */
+int open_namespace(struct ns_common *ns)
 {
-	struct path path = {};
-	struct ns_common *relative;
+	struct path path __free(path_put) = {};
 	struct file *f;
 	int err;
-	int fd;
 
-	fd = get_unused_fd_flags(O_CLOEXEC);
+	/* call first to consume reference */
+	err = path_from_stashed(&ns->stashed, nsfs_mnt, ns, &path);
+	if (err < 0)
+		return err;
+
+	CLASS(get_unused_fd, fd)(O_CLOEXEC);
 	if (fd < 0)
 		return fd;
 
-	relative = get_ns(ns);
-	if (IS_ERR(relative)) {
-		put_unused_fd(fd);
-		return PTR_ERR(relative);
-	}
+	f = dentry_open(&path, O_RDONLY, current_cred());
+	if (IS_ERR(f))
+		return PTR_ERR(f);
 
-	err = path_from_stashed(&relative->stashed, nsfs_mnt, relative, &path);
-	if (err < 0) {
-		put_unused_fd(fd);
-		return err;
-	}
+	fd_install(fd, f);
+	return take_fd(fd);
+}
 
-	f = dentry_open(&path, O_RDONLY, current_cred());
-	path_put(&path);
-	if (IS_ERR(f)) {
-		put_unused_fd(fd);
-		fd = PTR_ERR(f);
-	} else
-		fd_install(fd, f);
+int open_related_ns(struct ns_common *ns,
+		   struct ns_common *(*get_ns)(struct ns_common *ns))
+{
+	struct ns_common *relative;
+
+	relative = get_ns(ns);
+	if (IS_ERR(relative))
+		return PTR_ERR(relative);
 
-	return fd;
+	return open_namespace(relative);
 }
 EXPORT_SYMBOL_GPL(open_related_ns);
 
@@ -123,9 +132,12 @@ static long ns_ioctl(struct file *filp, unsigned int ioctl,
 			unsigned long arg)
 {
 	struct user_namespace *user_ns;
+	struct pid_namespace *pid_ns;
+	struct task_struct *tsk;
 	struct ns_common *ns = get_proc_ns(file_inode(filp));
 	uid_t __user *argp;
 	uid_t uid;
+	int ret;
 
 	switch (ioctl) {
 	case NS_GET_USERNS:
@@ -143,9 +155,69 @@ 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: {
+		struct mnt_namespace *mnt_ns;
+		__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->seq;
+		return put_user(id, idp);
+	}
+	case NS_GET_PID_FROM_PIDNS:
+		fallthrough;
+	case NS_GET_TGID_FROM_PIDNS:
+		fallthrough;
+	case NS_GET_PID_IN_PIDNS:
+		fallthrough;
+	case NS_GET_TGID_IN_PIDNS:
+		if (ns->ops->type != CLONE_NEWPID)
+			return -EINVAL;
+
+		ret = -ESRCH;
+		pid_ns = container_of(ns, struct pid_namespace, ns);
+
+		rcu_read_lock();
+
+		if (ioctl == NS_GET_PID_IN_PIDNS ||
+		    ioctl == NS_GET_TGID_IN_PIDNS)
+			tsk = find_task_by_vpid(arg);
+		else
+			tsk = find_task_by_pid_ns(arg, pid_ns);
+		if (!tsk)
+			break;
+
+		switch (ioctl) {
+		case NS_GET_PID_FROM_PIDNS:
+			ret = task_pid_vnr(tsk);
+			break;
+		case NS_GET_TGID_FROM_PIDNS:
+			ret = task_tgid_vnr(tsk);
+			break;
+		case NS_GET_PID_IN_PIDNS:
+			ret = task_pid_nr_ns(tsk, pid_ns);
+			break;
+		case NS_GET_TGID_IN_PIDNS:
+			ret = task_tgid_nr_ns(tsk, pid_ns);
+			break;
+		default:
+			ret = 0;
+			break;
+		}
+		rcu_read_unlock();
+
+		if (!ret)
+			ret = -ESRCH;
+		break;
 	default:
-		return -ENOTTY;
+		ret = -ENOTTY;
 	}
+
+	return ret;
 }
 
 int ns_get_name(char *buf, size_t size, struct task_struct *task,