[linux.git] / fs / sysfs / mount.c

// SPDX-License-Identifier: GPL-2.0
/*
 * fs/sysfs/symlink.c - operations for initializing and mounting sysfs
 *
 * Copyright (c) 2001-3 Patrick Mochel
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007 Tejun Heo <[email protected]>
 *
 * Please see Documentation/filesystems/sysfs.txt for more information.
 */

#include <linux/fs.h>
#include <linux/magic.h>
#include <linux/mount.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/user_namespace.h>
#include <linux/fs_context.h>
#include <net/net_namespace.h>

#include "sysfs.h"

static struct kernfs_root *sysfs_root;
struct kernfs_node *sysfs_root_kn;

static int sysfs_get_tree(struct fs_context *fc)
{
	struct kernfs_fs_context *kfc = fc->fs_private;
	int ret;

	ret = kernfs_get_tree(fc);
	if (ret)
		return ret;

	if (kfc->new_sb_created)
		fc->root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE;
	return 0;
}

static void sysfs_fs_context_free(struct fs_context *fc)
{
	struct kernfs_fs_context *kfc = fc->fs_private;

	if (kfc->ns_tag)
		kobj_ns_drop(KOBJ_NS_TYPE_NET, kfc->ns_tag);
	kernfs_free_fs_context(fc);
	kfree(kfc);
}

static const struct fs_context_operations sysfs_fs_context_ops = {
	.free		= sysfs_fs_context_free,
	.get_tree	= sysfs_get_tree,
};

static int sysfs_init_fs_context(struct fs_context *fc)
{
	struct kernfs_fs_context *kfc;
	struct net *netns;

	if (!(fc->sb_flags & SB_KERNMOUNT)) {
		if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
			return -EPERM;
	}

	kfc = kzalloc(sizeof(struct kernfs_fs_context), GFP_KERNEL);
	if (!kfc)
		return -ENOMEM;

	kfc->ns_tag = netns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
	kfc->root = sysfs_root;
	kfc->magic = SYSFS_MAGIC;
	fc->fs_private = kfc;
	fc->ops = &sysfs_fs_context_ops;
	if (fc->user_ns)
		put_user_ns(fc->user_ns);
	fc->user_ns = get_user_ns(netns->user_ns);
	fc->global = true;
	return 0;
}

static void sysfs_kill_sb(struct super_block *sb)
{
	void *ns = (void *)kernfs_super_ns(sb);

	kernfs_kill_sb(sb);
	kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
}

static struct file_system_type sysfs_fs_type = {
	.name			= "sysfs",
	.init_fs_context	= sysfs_init_fs_context,
	.kill_sb		= sysfs_kill_sb,
	.fs_flags		= FS_USERNS_MOUNT,
};

int __init sysfs_init(void)
{
	int err;

	sysfs_root = kernfs_create_root(NULL, KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
					NULL);
	if (IS_ERR(sysfs_root))
		return PTR_ERR(sysfs_root);

	sysfs_root_kn = sysfs_root->kn;

	err = register_filesystem(&sysfs_fs_type);
	if (err) {
		kernfs_destroy_root(sysfs_root);
		return err;
	}

	return 0;
}
Commit	Line	Data
619daeee	1	// SPDX-License-Identifier: GPL-2.0
1da177e4	2	/*
6d66f5cd TH	3	* fs/sysfs/symlink.c - operations for initializing and mounting sysfs
	4	*
	5	* Copyright (c) 2001-3 Patrick Mochel
	6	* Copyright (c) 2007 SUSE Linux Products GmbH
	7	* Copyright (c) 2007 Tejun Heo <[email protected]>
	8	*
6d66f5cd	9	* Please see Documentation/filesystems/sysfs.txt for more information.
1da177e4 LT	10	*/
1da177e4 LT	11
1da177e4	12	#include <linux/fs.h>
c9482a5b	13	#include <linux/magic.h>
1da177e4	14	#include <linux/mount.h>
1da177e4	15	#include <linux/init.h>
23bf1b6b	16	#include <linux/slab.h>
87a8ebd6	17	#include <linux/user_namespace.h>
23bf1b6b DH	18	#include <linux/fs_context.h>
23bf1b6b DH	19	#include <net/net_namespace.h>
1da177e4 LT	20
	21	#include "sysfs.h"
	22
ba7443bc	23	static struct kernfs_root *sysfs_root;
324a56e1	24	struct kernfs_node *sysfs_root_kn;
061447a4	25
23bf1b6b	26	static int sysfs_get_tree(struct fs_context *fc)
1da177e4	27	{
23bf1b6b DH	28	struct kernfs_fs_context *kfc = fc->fs_private;
23bf1b6b DH	29	int ret;
9e7fdd25	30
23bf1b6b DH	31	ret = kernfs_get_tree(fc);
	32	if (ret)
	33	return ret;
	34
	35	if (kfc->new_sb_created)
	36	fc->root->d_sb->s_iflags \|= SB_I_USERNS_VISIBLE;
	37	return 0;
	38	}
	39
	40	static void sysfs_fs_context_free(struct fs_context *fc)
	41	{
	42	struct kernfs_fs_context *kfc = fc->fs_private;
	43
	44	if (kfc->ns_tag)
	45	kobj_ns_drop(KOBJ_NS_TYPE_NET, kfc->ns_tag);
	46	kernfs_free_fs_context(fc);
	47	kfree(kfc);
	48	}
	49
	50	static const struct fs_context_operations sysfs_fs_context_ops = {
	51	.free = sysfs_fs_context_free,
	52	.get_tree = sysfs_get_tree,
	53	};
	54
	55	static int sysfs_init_fs_context(struct fs_context *fc)
	56	{
	57	struct kernfs_fs_context *kfc;
	58	struct net *netns;
	59
	60	if (!(fc->sb_flags & SB_KERNMOUNT)) {
c84a3b27	61	if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
23bf1b6b	62	return -EPERM;
7dc5dbc8	63	}
87a8ebd6	64
23bf1b6b DH	65	kfc = kzalloc(sizeof(struct kernfs_fs_context), GFP_KERNEL);
	66	if (!kfc)
	67	return -ENOMEM;
90f8572b	68
23bf1b6b DH	69	kfc->ns_tag = netns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
	70	kfc->root = sysfs_root;
	71	kfc->magic = SYSFS_MAGIC;
	72	fc->fs_private = kfc;
	73	fc->ops = &sysfs_fs_context_ops;
	74	if (fc->user_ns)
	75	put_user_ns(fc->user_ns);
	76	fc->user_ns = get_user_ns(netns->user_ns);
	77	fc->global = true;
	78	return 0;
4b93dc9b TH	79	}
4b93dc9b TH	80
9e7fdd25	81	static void sysfs_kill_sb(struct super_block *sb)
4b93dc9b	82	{
a7560a01 TH	83	void ns = (void )kernfs_super_ns(sb);
a7560a01 TH	84
4b93dc9b	85	kernfs_kill_sb(sb);
a7560a01	86	kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
4b93dc9b TH	87	}
4b93dc9b TH	88
1da177e4	89	static struct file_system_type sysfs_fs_type = {
23bf1b6b DH	90	.name = "sysfs",
	91	.init_fs_context = sysfs_init_fs_context,
	92	.kill_sb = sysfs_kill_sb,
	93	.fs_flags = FS_USERNS_MOUNT,
1da177e4 LT	94	};
1da177e4 LT	95
4b93dc9b TH	96	int __init sysfs_init(void)
	97	{
	98	int err;
e0bf68dd	99
555724a8 TH	100	sysfs_root = kernfs_create_root(NULL, KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
555724a8 TH	101	NULL);
4b93dc9b TH	102	if (IS_ERR(sysfs_root))
	103	return PTR_ERR(sysfs_root);
	104
324a56e1	105	sysfs_root_kn = sysfs_root->kn;
ba7443bc	106
1da177e4	107	err = register_filesystem(&sysfs_fs_type);
4b93dc9b TH	108	if (err) {
	109	kernfs_destroy_root(sysfs_root);
	110	return err;
	111	}
9e30cc95 TH	112
9e30cc95 TH	113	return 0;
1da177e4	114	}