Unverified Commit e8e43a1f authored by Josef Bacik's avatar Josef Bacik Committed by Christian Brauner
Browse files

fs: add an ioctl to get the mnt ns id from nsfs 



In order to utilize the listmount() and statmount() extensions that
allow us to call them on different namespaces we need a way to get the
mnt namespace id from user space.  Add an ioctl to nsfs that will allow
us to extract the mnt namespace id in order to make these new extensions
usable.

Signed-off-by: default avatarJosef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/180449959d5a756af7306d6bda55f41b9d53e3cb.1719243756.git.josef@toxicpanda.com


Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 71aacb4c

fs/nsfs.c

+14 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ 
#include <linux/nsfs.h>

#include <linux/uaccess.h>



#include "mount.h"

#include "internal.h"



static struct vfsmount *nsfs_mnt;
@@ -143,6 +144,19 @@ 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);

	}

	default:

		return -ENOTTY;

	}

include/uapi/linux/nsfs.h

+2 −0
Original line number Diff line number Diff line
@@ -15,5 +15,7 @@ 
#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		_IO(NSIO, 0x5)



#endif /* __LINUX_NSFS_H */