From e8e43a1fcc5c07575f37e40f8a2cd78aee46f9a0 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Mon, 24 Jun 2024 11:49:50 -0400 Subject: [PATCH] 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: Josef Bacik Link: https://lore.kernel.org/r/180449959d5a756af7306d6bda55f41b9d53e3cb.1719243756.git.josef@toxicpanda.com Signed-off-by: Christian Brauner --- fs/nsfs.c | 14 ++++++++++++++ include/uapi/linux/nsfs.h | 2 ++ 2 files changed, 16 insertions(+) diff --git a/fs/nsfs.c b/fs/nsfs.c index 07e22a15ef02b..af352dadffe16 100644 --- a/fs/nsfs.c +++ b/fs/nsfs.c @@ -12,6 +12,7 @@ #include #include +#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; } diff --git a/include/uapi/linux/nsfs.h b/include/uapi/linux/nsfs.h index a0c8552b64ee0..56e8b1639b98f 100644 --- a/include/uapi/linux/nsfs.h +++ b/include/uapi/linux/nsfs.h @@ -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 */