Unverified Commit b2a0b192 authored by Christian Brauner's avatar Christian Brauner
Browse files

mnt: expose pointer to init_mnt_ns 



There's various scenarios where we need to know whether we are in the
initial set of namespaces or not to e.g., shortcut permission checking.
All namespaces expose that information. Let's do that too.

Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
parent 93f67a7d

fs/namespace.c

+16 −11
Original line number Diff line number Diff line
@@ -6008,27 +6008,32 @@ SYSCALL_DEFINE4(listmount, const struct mnt_id_req __user *, req, 
	return ret;

}



struct mnt_namespace init_mnt_ns = {

	.ns.inum	= PROC_MNT_INIT_INO,

	.ns.ops		= &mntns_operations,

	.user_ns	= &init_user_ns,

	.ns.count	= REFCOUNT_INIT(1),

	.passive	= REFCOUNT_INIT(1),

	.mounts		= RB_ROOT,

	.poll		= __WAIT_QUEUE_HEAD_INITIALIZER(init_mnt_ns.poll),

};



static void __init init_mount_tree(void)

{

	struct vfsmount *mnt;

	struct mount *m;

	struct mnt_namespace *ns;

	struct path root;



	mnt = vfs_kern_mount(&rootfs_fs_type, 0, "rootfs", NULL);

	if (IS_ERR(mnt))

		panic("Can't create rootfs");



	ns = alloc_mnt_ns(&init_user_ns, true);

	if (IS_ERR(ns))

		panic("Can't allocate initial namespace");

	ns->ns.inum = PROC_MNT_INIT_INO;

	m = real_mount(mnt);

	ns->root = m;

	ns->nr_mounts = 1;

	mnt_add_to_ns(ns, m);

	init_task.nsproxy->mnt_ns = ns;

	get_mnt_ns(ns);

	init_mnt_ns.root = m;

	init_mnt_ns.nr_mounts = 1;

	mnt_add_to_ns(&init_mnt_ns, m);

	init_task.nsproxy->mnt_ns = &init_mnt_ns;

	get_mnt_ns(&init_mnt_ns);



	root.mnt = mnt;

	root.dentry = mnt->mnt_root;
@@ -6036,7 +6041,7 @@ static void __init init_mount_tree(void) 
	set_fs_pwd(current->fs, &root);

	set_fs_root(current->fs, &root);



	ns_tree_add(ns);

	ns_tree_add(&init_mnt_ns);

}



void __init mnt_init(void)

include/linux/mnt_namespace.h

+2 −0
Original line number Diff line number Diff line
@@ -11,6 +11,8 @@ struct fs_struct; 
struct user_namespace;

struct ns_common;



extern struct mnt_namespace init_mnt_ns;



extern struct mnt_namespace *copy_mnt_ns(unsigned long, struct mnt_namespace *,

		struct user_namespace *, struct fs_struct *);

extern void put_mnt_ns(struct mnt_namespace *ns);