cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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mount.c (2543B)

      1// SPDX-License-Identifier: GPL-2.0
      2/*
      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 <teheo@suse.de>
      8 *
      9 * Please see Documentation/filesystems/sysfs.rst for more information.
     10 */
     11
     12#include <linux/fs.h>
     13#include <linux/magic.h>
     14#include <linux/mount.h>
     15#include <linux/init.h>
     16#include <linux/slab.h>
     17#include <linux/user_namespace.h>
     18#include <linux/fs_context.h>
     19#include <net/net_namespace.h>
     20
     21#include "sysfs.h"
     22
     23static struct kernfs_root *sysfs_root;
     24struct kernfs_node *sysfs_root_kn;
     25
     26static int sysfs_get_tree(struct fs_context *fc)
     27{
     28	struct kernfs_fs_context *kfc = fc->fs_private;
     29	int ret;
     30
     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
     40static 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
     50static const struct fs_context_operations sysfs_fs_context_ops = {
     51	.free		= sysfs_fs_context_free,
     52	.get_tree	= sysfs_get_tree,
     53};
     54
     55static 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)) {
     61		if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
     62			return -EPERM;
     63	}
     64
     65	kfc = kzalloc(sizeof(struct kernfs_fs_context), GFP_KERNEL);
     66	if (!kfc)
     67		return -ENOMEM;
     68
     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 (netns) {
     75		put_user_ns(fc->user_ns);
     76		fc->user_ns = get_user_ns(netns->user_ns);
     77	}
     78	fc->global = true;
     79	return 0;
     80}
     81
     82static void sysfs_kill_sb(struct super_block *sb)
     83{
     84	void *ns = (void *)kernfs_super_ns(sb);
     85
     86	kernfs_kill_sb(sb);
     87	kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
     88}
     89
     90static struct file_system_type sysfs_fs_type = {
     91	.name			= "sysfs",
     92	.init_fs_context	= sysfs_init_fs_context,
     93	.kill_sb		= sysfs_kill_sb,
     94	.fs_flags		= FS_USERNS_MOUNT,
     95};
     96
     97int __init sysfs_init(void)
     98{
     99	int err;
    100
    101	sysfs_root = kernfs_create_root(NULL, KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
    102					NULL);
    103	if (IS_ERR(sysfs_root))
    104		return PTR_ERR(sysfs_root);
    105
    106	sysfs_root_kn = kernfs_root_to_node(sysfs_root);
    107
    108	err = register_filesystem(&sysfs_fs_type);
    109	if (err) {
    110		kernfs_destroy_root(sysfs_root);
    111		return err;
    112	}
    113
    114	return 0;
    115}